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Sample records for enhanced death signaling

  1. Enhanced signal-to-noise ratios in frog hearing can be achieved through amplitude death

    PubMed Central

    Ahn, Kang-Hun

    2013-01-01

    In the ear, hair cells transform mechanical stimuli into neuronal signals with great sensitivity, relying on certain active processes. Individual hair cell bundles of non-mammals such as frogs and turtles are known to show spontaneous oscillation. However, hair bundles in vivo must be quiet in the absence of stimuli, otherwise the signal is drowned in intrinsic noise. Thus, a certain mechanism is required in order to suppress intrinsic noise. Here, through a model study of elastically coupled hair bundles of bullfrog sacculi, we show that a low stimulus threshold and a high signal-to-noise ratio (SNR) can be achieved through the amplitude death phenomenon (the cessation of spontaneous oscillations by coupling). This phenomenon occurs only when the coupled hair bundles have inhomogeneous distribution, which is likely to be the case in biological systems. We show that the SNR has non-monotonic dependence on the mass of the overlying membrane, and find out that the SNR has maximum value in the region of amplitude death. The low threshold of stimulus through amplitude death may account for the experimentally observed high sensitivity of frog sacculi in detecting vibration. The hair bundles' amplitude death mechanism provides a smart engineering design for low-noise amplification. PMID:23883956

  2. miR-181 interacts with signaling adaptor molecule DENN/MADD and enhances TNF-induced cell death

    PubMed Central

    Ghorbani, Samira; Talebi, Farideh; Ghasemi, Sedigheh; Jahanbazi Jahan Abad, Ali; Vojgani, Mohammed; Noorbakhsh, Farshid

    2017-01-01

    MicroRNAs are small noncoding RNAs, which regulate the expression of protein coding transcripts through mRNA degradation or translational inhibition. Numerous reports have highlighted the role of miRNAs in regulating cell death pathways including the expression of genes involved in the induction of apoptosis. Tumor necrosis factor alpha (TNF-α) is a proinflammatory cytokine which can send pro-death signals through its receptor TNFR1. Diverse adaptor molecules including DENN/MADD adaptor protein have been shown to modulate TNF-α pro-death signaling via recruitment of MAP kinases to TNFR1 and activation of pro-survival NFκB signaling. Herein, we investigated the role of microRNA-181 (miR-181) in regulating DENN/MADD expression levels and its subsequent effects on TNF-α-induced cell death. Using bioinformatics analyses followed by luciferase reporter assays we showed that miR-181 interacts with the 3’ UTR of DENN/MADD transcripts. miR-181 overexpression also led to decreased endogenous DENN/MADD mRNA levels in L929 murine fibroblasts. Flow cytometric analysis of miR-181 transfected cells showed this miRNA accentuates mitochondrial membrane potential loss caused by TNF-α. These findings were associated with enhanced apoptosis of L929 cells following TNF-α treatment. Overall, these data point to the potential role of miR-181 in regulating TNF-α pro-death signaling, which could be of importance from pathogenesis and therapeutic perspectives in inflammatory disorders associated with tissue degeneration and cell death. PMID:28323882

  3. Suppression of death receptor 5 enhances cancer cell invasion and metastasis through activation of caspase-8/TRAF2-mediated signaling.

    PubMed

    Oh, You-Take; Yue, Ping; Wang, Dongsheng; Tong, Jing-Shan; Chen, Zhuo G; Khuri, Fadlo R; Sun, Shi-Yong

    2015-12-01

    The role of death receptor 5 (DR5), a well-known cell surface pro-apoptotic protein, in the negative regulation of invasion and metastasis of human cancer cells and the underlying mechanisms are largely unknown and were hence the focus of this study. In this report, we have demonstrated that DR5 functions to suppress invasion and metastasis of human cancer cells, as evidenced by enhanced cancer cell invasion and metastasis upon genetic suppression of DR5 either by gene knockdown or knockout. When DR5 is suppressed, FADD and caspase-8 may recruit and stabilize TRAF2 to form a metastasis and invasion signaling complex, resulting in activation of ERK and JNK/AP-1 signaling that mediate the elevation and activation of matrix metalloproteinase-1 (MMP1) and eventual promotion of cancer invasion and metastasis. Our findings thus highlight a novel non-apoptotic function of DR5 as a suppressor of human cancer cell invasion and metastasis and suggest a basic working model elucidating the underlying biology.

  4. Streptolysin S Promotes Programmed Cell Death and Enhances Inflammatory Signaling in Epithelial Keratinocytes during Group A Streptococcus Infection

    PubMed Central

    Flaherty, Rebecca A.; Puricelli, Jessica M.; Higashi, Dustin L.; Park, Claudia J.

    2015-01-01

    Streptococcus pyogenes, or group A Streptococcus (GAS), is a pathogen that causes a multitude of human diseases from pharyngitis to severe infections such as toxic shock syndrome and necrotizing fasciitis. One of the primary virulence factors produced by GAS is the peptide toxin streptolysin S (SLS). In addition to its well-recognized role as a cytolysin, recent evidence has indicated that SLS may influence host cell signaling pathways at sublytic concentrations during infection. We employed an antibody array-based approach to comprehensively identify global host cell changes in human epithelial keratinocytes in response to the SLS toxin. We identified key SLS-dependent host responses, including the initiation of specific programmed cell death and inflammatory cascades with concomitant downregulation of Akt-mediated cytoprotection. Significant signaling responses identified by our array analysis were confirmed using biochemical and protein identification methods. To further demonstrate that the observed SLS-dependent host signaling changes were mediated primarily by the secreted toxin, we designed a Transwell infection system in which direct bacterial attachment to host cells was prevented, while secreted factors were allowed access to host cells. The results using this approach were consistent with our direct infection studies and reveal that SLS is a bacterial toxin that does not require bacterial attachment to host cells for activity. In light of these findings, we propose that the production of SLS by GAS during skin infection promotes invasive outcomes by triggering programmed cell death and inflammatory cascades in host cells to breach the keratinocyte barrier for dissemination into deeper tissues. PMID:26238711

  5. Interleukin-8 enhances the effect of colchicine on cell death.

    PubMed

    Yokoyama, Chikako; Yajima, Chika; Machida, Tetsuro; Kawahito, Yuji; Uchida, Marie; Hisatomi, Hisashi

    2017-03-25

    Pro-inflammatory cytokines are known to be generated in tumors and play important roles in angiogenesis, mitosis, and tumor progression. However, few studies have investigated the synergistic effects of pro-inflammatory cytokines and anticancer drugs on cell death. In the present study, we examined the combined effects of pro-inflammatory cytokines and colchicine on cell death of cancer cells. Colchicine induces G2/M arrest in the cell cycle by binding to tubulin, one of the main constituents of microtubules. SUIT-2 human pancreatic cancer cell line cells overexpressing pro-inflammatory cytokines, including interleukin (IL)-1β, IL-8, and tumor necrosis factor (TNF)-α, were treated with colchicine. The effect of colchicine on cell death was enhanced in cells overexpressing IL-8. Moreover, the effect of colchicine on cell death was enhanced in cells overexpressing two IL-8 up-regulators, NF-κB and IL-6, but not in cells overexpressing an IL-8 down-regulator, splicing factor proline/glutamine-rich (SFPQ). Synergistic effects of IL-8 and colchicine were also observed in cells overexpressing IL-8 isoforms lacking the signal peptide. Therefore, IL-8 appeared to function as an enhancer of cell death in cancer cells treated with colchicine. The present results suggest a new role for IL-8 related to cell death of cancer cells.

  6. Cell Death Signaling and Anticancer Therapy

    PubMed Central

    Galluzzi, Lorenzo; Vitale, Ilio; Vacchelli, Erika; Kroemer, Guido

    2011-01-01

    For a long time, it was commonly believed that efficient anticancer regimens would either trigger the apoptotic demise of tumor cells or induce a permanent arrest in the G1 phase of the cell cycle, i.e., senescence. The recent discovery that necrosis can occur in a regulated fashion and the increasingly more precise characterization of the underlying molecular mechanisms have raised great interest, as non-apoptotic pathways might be instrumental to circumvent the resistance of cancer cells to conventional, pro-apoptotic therapeutic regimens. Moreover, it has been shown that some anticancer regimens engage lethal signaling cascades that can ignite multiple oncosuppressive mechanisms, including apoptosis, necrosis, and senescence. Among these signaling pathways is mitotic catastrophe, whose role as a bona fide cell death mechanism has recently been reconsidered. Thus, anticancer regimens get ever more sophisticated, and often distinct strategies are combined to maximize efficacy and minimize side effects. In this review, we will discuss the importance of apoptosis, necrosis, and mitotic catastrophe in the response of tumor cells to the most common clinically employed and experimental anticancer agents. PMID:22655227

  7. Cell death signaling and anticancer therapy.

    PubMed

    Galluzzi, Lorenzo; Vitale, Ilio; Vacchelli, Erika; Kroemer, Guido

    2011-01-01

    For a long time, it was commonly believed that efficient anticancer regimens would either trigger the apoptotic demise of tumor cells or induce a permanent arrest in the G(1) phase of the cell cycle, i.e., senescence. The recent discovery that necrosis can occur in a regulated fashion and the increasingly more precise characterization of the underlying molecular mechanisms have raised great interest, as non-apoptotic pathways might be instrumental to circumvent the resistance of cancer cells to conventional, pro-apoptotic therapeutic regimens. Moreover, it has been shown that some anticancer regimens engage lethal signaling cascades that can ignite multiple oncosuppressive mechanisms, including apoptosis, necrosis, and senescence. Among these signaling pathways is mitotic catastrophe, whose role as a bona fide cell death mechanism has recently been reconsidered. Thus, anticancer regimens get ever more sophisticated, and often distinct strategies are combined to maximize efficacy and minimize side effects. In this review, we will discuss the importance of apoptosis, necrosis, and mitotic catastrophe in the response of tumor cells to the most common clinically employed and experimental anticancer agents.

  8. On involvement of transcription factors nuclear factor kappa-light-chain-enhancer of activated B cells, activator protein-1 and signal transducer and activator of transcription-3 in photodynamic therapy-induced death of crayfish neurons and satellite glial cells

    NASA Astrophysics Data System (ADS)

    Berezhnaya, Elena; Neginskaya, Marya; Kovaleva, Vera; Sharifulina, Svetlana; Ischenko, Irina; Komandirov, Maxim; Rudkovskii, Mikhail; Uzdensky, Anatoly B.

    2015-07-01

    Photodynamic therapy (PDT) is currently used in the treatment of brain tumors. However, not only malignant cells but also neighboring normal neurons and glial cells are damaged during PDT. In order to study the potential role of transcription factors-nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), activator protein (AP-1), and signal transducer and activator of transcription-3 (STAT-3)-in photodynamic injury of normal neurons and glia, we photosensitized the isolated crayfish mechanoreceptor consisting of a single sensory neuron enveloped by glial cells. Application of different inhibitors and activators showed that transcription factors NF-κB (inhibitors caffeic acid phenethyl ester and parthenolide, activator betulinic acid), AP-1 (inhibitor SR11302), and STAT-3 (inhibitors stattic and cucurbitacine) influenced PDT-induced death and survival of neurons and glial cells in different ways. These experiments indicated involvement of NF-κB in PDT-induced necrosis of neurons and apoptosis of glial cells. However, in glial cells, it played the antinecrotic role. AP-1 was not involved in PDT-induced necrosis of neurons and glia, but mediated glial apoptosis. STAT-3 was involved in PDT-induced apoptosis of glial cells and necrosis of neurons and glia. Therefore, signaling pathways that regulate cell death and survival in neurons and glial cells are different. Using various inhibitors or activators of transcription factors, one can differently influence the sensitivity and resistance of neurons and glial cells to PDT.

  9. Activating Cell Death Ligand Signaling Through Proteasome Inhibition

    DTIC Science & Technology

    2009-05-01

    Activating Cell Death Ligand Signaling Through Proteasome Inhibition PRINCIPAL INVESTIGATOR: Steven R Schwarze...SUBTITLE Activating Cell Death Ligand Signaling Through 5a. CONTRACT NUMBER Proteasome Inhibition 5b. GRANT NUMBER W81XWH-08-1-0392 5c...proteasome inhibition can act as an anti-neoplastic agent in vivo by sensitizing cancer cells to cell death ligands in the tumor microenvironment

  10. The Janus Face of Death Receptor Signaling during Tumor Immunoediting

    PubMed Central

    O’ Reilly, Eimear; Tirincsi, Andrea; Logue, Susan E.; Szegezdi, Eva

    2016-01-01

    Cancer immune surveillance is essential for the inhibition of carcinogenesis. Malignantly transformed cells can be recognized by both the innate and adaptive immune systems through different mechanisms. Immune effector cells induce extrinsic cell death in the identified tumor cells by expressing death ligand cytokines of the tumor necrosis factor ligand family. However, some tumor cells can escape immune elimination and progress. Acquisition of resistance to the death ligand-induced apoptotic pathway can be obtained through cleavage of effector cell expressed death ligands into a poorly active form, mutations or silencing of the death receptors, or overexpression of decoy receptors and pro-survival proteins. Although the immune system is highly effective in the elimination of malignantly transformed cells, abnormal/dysfunctional death ligand signaling curbs its cytotoxicity. Moreover, DRs can also transmit pro-survival and pro-migratory signals. Consequently, dysfunctional death receptor-mediated apoptosis/necroptosis signaling does not only give a passive resistance against cell death but actively drives tumor cell motility, invasion, and contributes to consequent metastasis. This dual contribution of the death receptor signaling in both the early, elimination phase, and then in the late, escape phase of the tumor immunoediting process is discussed in this review. Death receptor agonists still hold potential for cancer therapy since they can execute the tumor-eliminating immune effector function even in the absence of activation of the immune system against the tumor. The opportunities and challenges of developing death receptor agonists into effective cancer therapeutics are also discussed. PMID:27843441

  11. Tomato 14-3-3 protein 7 (TFT7) positively regulates immunity-associated programmed cell death by enhancing accumulation and signaling ability of MAPKKKalpha

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Programmed cell death (PCD) is triggered when Pto, a serine-threonine protein kinase recognizes either the AvrPto or AvrPtoB effector from Pseudomonas syringae pv. tomato. This PCD requires MAPKKKalpha as a positive regulator in tomato and Nicotiana benthamiana. To examine how PCD-eliciting activi...

  12. EP2 Receptor Signaling Regulates Microglia Death

    PubMed Central

    Yang, Myung-Soon; Jiang, Jianxiong; Ganesh, Thota; Joe, Eunhye; Dingledine, Raymond

    2015-01-01

    The timely resolution of inflammation prevents continued tissue damage after an initial insult. In the brain, the death of activated microglia by apoptosis has been proposed as one mechanism to resolve brain inflammation. How microglial death is regulated after activation is still unclear. We reported that exposure to lipopolysaccharide (LPS) and interleukin (IL)-13 together initially activates and then kills rat microglia in culture by a mechanism dependent on cyclooxygenase-2 (COX-2). We show here that activation of the E prostanoid receptor 2 (EP2, PTGER2) for prostaglandin E2 mediates microglial death induced by LPS/IL-13, and that EP2 activation by agonist alone kills microglia. Both EP2 antagonists and reactive oxygen scavengers block microglial death induced by either LPS/IL-13 or EP2 activation. By contrast, the homeostatic induction of heme oxygenase 1 (Hmox1) by LPS/IL-13 or EP2 activation protects microglia. Both the Hmox1 inducer cobalt protoporphyrin and a compound that releases the Hmox1 product carbon monoxide (CO) attenuated microglial death produced by LPS/IL-13. Whereas CO reduced COX-2 protein expression, EP2 activation increased Hmox1 and COX-2 expression at both the mRNA and protein level. Interestingly, caspase-1 inhibition prevented microglial death induced by either LPS/IL-13 or low (but not high) concentrations of butaprost, suggestive of a predominantly pyroptotic mode of death. Butaprost also caused the expression of activated caspase-3 in microglia, pointing to apoptosis. These results indicate that EP2 activation, which initially promotes microglial activation, later causes delayed death of activated microglia, potentially contributing to the resolution phase of neuroinflammation. PMID:25715797

  13. Surviving apoptosis: life-death signaling in single cells

    PubMed Central

    Flusberg, Deborah A.; Sorger, Peter K.

    2015-01-01

    Tissue development and homeostasis are regulated by opposing pro-survival and pro-death signals. An interesting feature of the Tumor Necrosis Factor (TNF) family of ligands is that they simultaneously activate opposing signals within a single cell via the same ligand-receptor complex. The magnitude of pro-death events such as caspase activation and pro-survival events such as NF-κB activation vary not only from one cell type to the next but also among individual cells of the same type due to intrinsic and extrinsic noise. The molecules involved in these pro-survival/pro-death pathways, and the different phenotypes that result from their activities, have been recently reviewed. Here we focus on the impact of cell-to-cell variability in the strength of these opposing signals on shaping cell fate decisions. PMID:25920803

  14. Jasmonic acid signaling modulates ozone-induced hypersensitive cell death.

    PubMed

    Rao, M V; Lee, H; Creelman, R A; Mullet, J E; Davis, K R

    2000-09-01

    Recent studies suggest that cross-talk between salicylic acid (SA)-, jasmonic acid (JA)-, and ethylene-dependent signaling pathways regulates plant responses to both abiotic and biotic stress factors. Earlier studies demonstrated that ozone (O(3)) exposure activates a hypersensitive response (HR)-like cell death pathway in the Arabidopsis ecotype Cvi-0. We now have confirmed the role of SA and JA signaling in influencing O(3)-induced cell death. Expression of salicylate hydroxylase (NahG) in Cvi-0 reduced O(3)-induced cell death. Methyl jasmonate (Me-JA) pretreatment of Cvi-0 decreased O(3)-induced H(2)O(2) content and SA concentrations and completely abolished O(3)-induced cell death. Cvi-0 synthesized as much JA as did Col-0 in response to O(3) exposure but exhibited much less sensitivity to exogenous Me-JA. Analyses of the responses to O(3) of the JA-signaling mutants jar1 and fad3/7/8 also demonstrated an antagonistic relationship between JA- and SA-signaling pathways in controlling the magnitude of O(3)-induced HR-like cell death.

  15. Using Literal Text From the Death Certificate to Enhance Mortality Statistics: Characterizing Drug Involvement in Deaths.

    PubMed

    Trinidad, James P; Warner, Margaret; Bastian, Brigham A; Minino, Arialdi M; Hedegaard, Holly

    2016-12-01

    Objectives-This report describes the development and use of a method for analyzing the literal text from death certificates to enhance national mortality statistics on drug-involved deaths. Drug-involved deaths include drug overdose deaths as well as other deaths where, according to death certificate literal text, drugs were associated with or contributed to the death. Methods-The method uses final National Vital Statistics System-Mortality files linked to electronic files containing literal text information from death certificates. Software programs were designed to search the literal text from three fields of the death certificate (the cause of death from Part I, significant conditions contributing to the death from Part II, and a description of how the injury occurred from Box 43) to identify drug mentions as well as contextual information. The list of drug search terms was developed from existing drug classification systems as well as from manual review of the literal text. Literal text surrounding the identified drug search terms was analyzed to ascertain the context. Drugs mentioned in the death certificate literal text were assumed to be involved in the death unless contextual information suggested otherwise (e.g., "METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS INFECTION"). The literal text analysis method was assessed by comparing the results from application of the method with results based on ICD-10 codes, and by conducting a manual review of a sample of records.

  16. Signaling pathway for apoptosis: a racetrack for life or death.

    PubMed

    Wang, E; Marcotte, R; Petroulakis, E

    1999-01-01

    Apoptosis, or programmed cell death, is a gene-directed mechanism activated as a suicidal event to get rid of excess, damaged, or infected cells. The recent astounding pace of research in this area has expanded our horizon of understanding that this mechanism is regulated largely by pro- and anti-apoptosis factors acting for or against the final death event. The driving force behind these factors, either pro-apoptosis or pro-survival, is largely determined by signal transduction pathways, starting with the initiation of a death signal at the plasma membrane, and following through a complex cytoplasmic network before reaching the end point of cell demise. Enmeshed in this intricate cytoplasmic network are many checkpoints, where complexes of pro- and anti-apoptosis factors function to facilitate or deter the death signals. The culmination of the balancing act between these two camps of factors at these signal transduction checkpoints may then result in the final decision to die or to live. Thus, the eventual death of a cell may require successful passage through all the checkpoints, a mechanism Nature has provided as a safeguard to prevent erroneous triggering of death. With the advent of a new biotechnology revolution at the dawn of the new millenium, we look forward to an exciting era when we can gain fuller understanding of the operation of all these checkpoints. Ultimately, this gain will pave the way to control the apoptosis event at the checkpoints, and to support the organism's functionality as long as possible. J. Cell. Biochem. Suppls. 32/33:95-102, 1999.

  17. RSL3 and Erastin differentially regulate redox signaling to promote Smac mimetic-induced cell death

    PubMed Central

    Dächert, Jasmin; Schoeneberger, Hannah; Rohde, Katharina; Fulda, Simone

    2016-01-01

    Redox mechanisms play an important role in the control of various signaling pathways. Here, we report that Second mitochondrial activator of caspases (Smac) mimetic-induced cell death is regulated by redox signaling. We show that RSL3, a glutathione (GSH) peroxidase (GPX) 4 inhibitor, or Erastin, an inhibitor of the cystine/glutamate antiporter, cooperate with the Smac mimetic BV6 to induce reactive oxygen species (ROS)-dependent cell death in acute lymphoblastic leukemia (ALL) cells. Addition of the caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD.fmk) fails to rescue ROS-induced cell death, demonstrating that RSL3/BV6- or Erastin/BV6-induced cell death occurs in a caspase-independent manner. Interestingly, the iron chelator Deferoxamine (DFO) significantly inhibits RSL3/BV6-induced cell death, whereas it is unable to rescue cell death by Erastin/BV6, showing that RSL3/BV6-, but not Erastin/BV6-mediated cell death depends on iron. ROS production is required for both RSL3/BV6- and Erastin/BV6-induced cell death, since the ROS scavenger α-tocopherol (α-Toc) rescues RSL3/BV6- and Erastin/BV6-induced cell death. By comparison, genetic or pharmacological inhibition of lipid peroxidation by GPX4 overexpression or ferrostatin (Fer)-1 significantly decreases RSL3/BV6-, but not Erastin/BV6-induced cell death, despite inhibition of lipid peroxidation upon exposure to RSL3/BV6 or Erastin/BV6. Of note, inhibition of lipid peroxidation by Fer-1 protects from RSL3/BV6-, but not from Erastin/BV6-stimulated ROS production, indicating that other forms of ROS besides lipophilic ROS occur during Erastin/BV6-induced cell death. Taken together, RSL3/BV6 and Erastin/BV6 differentially regulate redox signaling and cell death in ALL cells. While RSL3/BV6 cotreatment induces ferroptotic cell death, Erastin/BV6 stimulates oxidative cell death independently of iron. These findings have important implications for the therapeutic targeting of redox signaling to

  18. Danger signalling during cancer cell death: origins, plasticity and regulation.

    PubMed

    Garg, A D; Martin, S; Golab, J; Agostinis, P

    2014-01-01

    Accumulating data indicates that following anti-cancer treatments, cancer cell death can be perceived as immunogenic or tolerogenic by the immune system. The former is made possible due to the ability of certain anti-cancer modalities to induce immunogenic cell death (ICD) that is associated with the emission of damage-associated molecular patterns (DAMPs), which assist in unlocking a sequence of events leading to the development of anti-tumour immunity. In response to ICD inducers, activation of endoplasmic reticulum (ER) stress has been identified to be indispensable to confer the immunogenic character of cancer cell death, due to its ability to coordinate the danger signalling pathways responsible for the trafficking of vital DAMPs and subsequent anti-cancer immune responses. However, in recent times, certain processes apart from ER stress have emerged (e.g., autophagy and possibly viral response-like signature), which have the ability to influence danger signalling. In this review, we discuss the molecular nature, emerging plasticity in the danger signalling mechanisms and immunological impact of known DAMPs in the context of immunogenic cancer cell death. We also discuss key effector mechanisms modulating the interface between dying cancer cells and the immune cells, which we believe are crucial for the therapeutic relevance of ICD in the context of human cancers, and also discuss the influence of experimental conditions and animal models on these.

  19. Cullin-4 regulates Wingless and JNK signaling-mediated cell death in the Drosophila eye

    PubMed Central

    Tare, Meghana; Sarkar, Ankita; Bedi, Shimpi; Kango-Singh, Madhuri; Singh, Amit

    2016-01-01

    In all multicellular organisms, the fundamental processes of cell proliferation and cell death are crucial for growth regulation during organogenesis. Strict regulation of cell death is important to maintain tissue homeostasis by affecting processes like regulation of cell number, and elimination of unwanted/unfit cells. The developing Drosophila eye is a versatile model to study patterning and growth, where complex signaling pathways regulate growth and cell survival. However, the molecular mechanisms underlying regulation of these processes is not fully understood. In a gain-of-function screen, we found that misexpression of cullin-4 (cul-4), an ubiquitin ligase, can rescue reduced eye mutant phenotypes. Previously, cul-4 has been shown to regulate chromatin remodeling, cell cycle and cell division. Genetic characterization of cul-4 in the developing eye revealed that loss-of-function of cul-4 exhibits a reduced eye phenotype. Analysis of twin-spots showed that in comparison with their wild-type counterparts, the cul-4 loss-of-function clones fail to survive. Here we show that cul-4 clones are eliminated by induction of cell death due to activation of caspases. Aberrant activation of signaling pathways is known to trigger cell death in the developing eye. We found that Wingless (Wg) and c-Jun-amino-terminal-(NH2)-Kinase (JNK) signaling are ectopically induced in cul-4 mutant clones, and these signals co-localize with the dying cells. Modulating levels of Wg and JNK signaling by using agonists and antagonists of these pathways demonstrated that activation of Wg and JNK signaling enhances cul-4 mutant phenotype, whereas downregulation of Wg and JNK signaling rescues the cul-4 mutant phenotypes of reduced eye. Here we present evidences to demonstrate that cul-4 is involved in restricting Wg signaling and downregulation of JNK signaling-mediated cell death during early eye development. Overall, our studies provide insights into a novel role of cul-4 in promoting cell

  20. Activation of ERK signaling and induction of colon cancer cell death by piperlongumine.

    PubMed

    Randhawa, H; Kibble, K; Zeng, H; Moyer, M P; Reindl, K M

    2013-09-01

    Piperlongumine (PPLGM) is a bioactive compound isolated from long peppers that shows selective toxicity towards a variety of cancer cell types including colon cancer. The signaling pathways that lead to cancer cell death in response to PPLGM exposure have not been previously identified. Our objective was to identify the intracellular signaling mechanisms by which PPLGM leads to enhanced colon cancer cell death. We found that PPLGM inhibited the growth of colon cancer cells in time- and concentration-dependent manners, but was not toxic toward normal colon mucosal cells at concentrations below 10 μM. Acute (0-60 min) and prolonged (24h) exposure of HT-29 cells to PPLGM resulted in phosphorylation of ERK. To investigate whether ERK signaling was involved in PPLGM-mediated cell death, we treated HT-29 cells with the MEK inhibitor U0126, prior to treating with PPLGM. We found that U0126 attenuated PPLGM-induced activation of ERK and partially protected against PPLGM-induced cell death. These results suggest that PPLGM works, at least in part, through the MEK/ERK pathway to result in colon cancer cell death. A more thorough understanding of the molecular mechanisms by which PPLGM induces colon cancer cell death will be useful in developing therapeutic strategies to treat colon cancer.

  1. Fas death receptor signalling: roles of Bid and XIAP

    PubMed Central

    Kaufmann, T; Strasser, A; Jost, P J

    2012-01-01

    Fas (also called CD95 or APO-1), a member of a subgroup of the tumour necrosis factor receptor superfamily that contain an intracellular death domain, can initiate apoptosis signalling and has a critical role in the regulation of the immune system. Fas-induced apoptosis requires recruitment and activation of the initiator caspase, caspase-8 (in humans also caspase-10), within the death-inducing signalling complex. In so-called type 1 cells, proteolytic activation of effector caspases (-3 and -7) by caspase-8 suffices for efficient apoptosis induction. In so-called type 2 cells, however, killing requires amplification of the caspase cascade. This can be achieved through caspase-8-mediated proteolytic activation of the pro-apoptotic Bcl-2 homology domain (BH)3-only protein BH3-interacting domain death agonist (Bid), which then causes mitochondrial outer membrane permeabilisation. This in turn leads to mitochondrial release of apoptogenic proteins, such as cytochrome c and, pertinent for Fas death receptor (DR)-induced apoptosis, Smac/DIABLO (second mitochondria-derived activator of caspase/direct IAP binding protein with low Pi), an antagonist of X-linked inhibitor of apoptosis (XIAP), which imposes a brake on effector caspases. In this review, written in honour of Juerg Tschopp who contributed so much to research on cell death and immunology, we discuss the functions of Bid and XIAP in the control of Fas DR-induced apoptosis signalling, and we speculate on how this knowledge could be exploited to develop novel regimes for treatment of cancer. PMID:21959933

  2. Enhancing Anti-Breast Cancer Immunity by Blocking Death Receptor DR5

    DTIC Science & Technology

    2009-09-01

    encoding full length human DR5, phDR5∆ encoding human DR5 with a premature termination signal in the death domain (aa.1-338) and phDR5ECTM encoding the...by Blocking Death Receptor DR5 PRINCIPAL INVESTIGATOR: Wei-Zen Wei, Ph.D. CONTRACTING ORGANIZATION: Wayne State University...Annual 3. DATES COVERED 1 Sep 2008 – 31 Aug 2009 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Enhancing Anti-Breast Cancer Immunity by Blocking Death

  3. Tomato MAPKKKε is a positive regulator of cell-death signaling networks associated with plant immunity.

    PubMed

    Melech-Bonfil, Shiri; Sessa, Guido

    2010-11-01

    Mitogen-activated protein (MAP) kinase cascades are fundamental components of the signaling pathways associated with plant immunity. Despite the large number of MAP kinase kinase kinases (MAPKKK) encoded in the plant genome, only very few of them have an assigned function. Here, we identified MAPKKK gene of tomato (Solanum lycopersicum), SIMAPKKKε, which is required for hypersensitive response cell death and disease resistance against Gram-negative bacterial pathogens. Silencing of SIMAPKKKε compromised tomato resistance to Xanthomonas campestris and Pseudomonas syringae strains, resulting in the appearance of disease symptoms and enhanced bacterial growth. In addition, silencing of NbMAPKKKε in Nicotiana benthamiana plants significantly inhibited the cell death triggered by expression of different R gene/effector gene pairs. Conversely, overexpression of either the full-length SIMAPKKKε gene or its kinase domain in N. benthamiana leaves caused pathogen-independent activation of cell death that required an intact kinase catalytic domain. Moreover, by suppressing the expression of various MAPKK and MAPK genes and overexpressing the SIMAPKKKε kinase domain, we identified a signaling cascade acting downstream of SIMAPKKKε that includes MEK2, WIPK and SIPK. Additional epistasis experiments revealed that SIPKK functions as a negative regulator of SIMAPKKKε-mediated cell death. Our results provide evidence that SIMAPKKKε is a signaling molecule that positively regulates cell death networks associated with plant immunity.

  4. Cell death and survival signalling in the cardiovascular system.

    PubMed

    Tucka, Joanna; Bennett, Martin; Littlewood, Trevor

    2012-01-01

    The loss of cells is an important factor in many diseases, including those of the cardiovascular system. Whereas apoptosis is an essential process in development and tissue homeostasis, its occurrence is often associated with various pathologies. Apoptosis of neurons that fail to make appropriate connections is essential for the selection of correct neural signalling in the developing embryo, but its appearance in adults is often associated with neurodegenerative disease. Similarly, in the cardiovascular system, remodeling of the mammalian outflow tract during the transition from a single to dual series circulation with four chambers is accompanied by a precise pattern of cell death, but apoptosis of cardiomyocytes contributes to ischemia-reperfusion injury in the heart. In many cases, it is unclear whether apoptosis represents a causative association or merely a consequence of the disease itself. There are many excellent reviews on cell death in the cardiovascular system (1-5); in this review we outline the critical signalling pathways that promote the survival of cardiovascular cells, and their relevance to both physiological cell death and disease.

  5. Regulation of Neuroinflammation through Programed Death-1/Programed Death Ligand Signaling in Neurological Disorders

    PubMed Central

    Zhao, Shangfeng; Li, Fengwu; Leak, Rehana K.; Chen, Jun; Hu, Xiaoming

    2014-01-01

    Immune responses in the central nervous system (CNS), which involve both resident glial cells and infiltrating peripheral immune cells, play critical roles in the progress of brain injuries and neurodegeneration. To avoid inflammatory damage to the compromised brain, the immune cell activities in the CNS are controlled by a plethora of chemical mediators and signal transduction cascades, such as inhibitory signaling through programed death-1 (PD-1) and programed death ligand (PD-L) interactions. An increasing number of recent studies have highlighted the importance of PD-1/PD-L pathway in immune regulation in CNS disorders such as ischemic stroke, multiple sclerosis, and Alzheimer’s disease. Here, we review the current knowledge of the impact of PD-1/PD-L signaling on brain injury and neurodegeneration. An improved understanding of the function of PD-1/PD-L in the cross-talk between peripheral immune cells, CNS glial cells, and non-immune CNS cells is expected to shed further light on immunomodulation and help develop effective and safe immunotherapies for CNS disorders. PMID:25232304

  6. Dopamine Promotes Striatal Neuronal Apoptotic Death via ERK Signaling Cascades

    PubMed Central

    Chen, Jun; Rusnak, Milan; Lombroso, Paul J.; Sidhu, Anita

    2009-01-01

    Although the mechanisms underlying striatal neurodegeneration are poorly understood, we have shown that striatal pathogenesis may be initiated by high synaptic levels of extracellular dopamine (DA). Here we investigated in rat striatal primary neurons the mobilization of the mitogen activated protein kinase (MAPK) signaling pathways after treatment with DA. Instead of observing an elevation of the archetypical pro-cytotoxic MAPKs, p-JNK and p-p38 MAPK, we found that DA, acting through D1 DA receptors, induced a sustained stimulation of the phosphorylated form of extracellular signal-regulated kinase (p-ERK) via a cAMP/PKA/Rap1/B-Raf/MEK pathway. Blockade of D2 DA receptors, β-adrenergic receptors or NMDA receptors with receptor-specific antagonists had no significant effect on this process. Activation of D1 DA receptors and PKA by DA caused phosphorylation and inactivation of the striatal–enriched tyrosine phosphatase (STEP), an important phosphatase for the dephosphorylation and subsequent inactivation of p-ERK in striatum. Interestingly p-ERK was primarily retained in the cytoplasm, with only low amounts translocated to the nucleus. The scaffold protein β-arrestin2 interacted with both p-ERK and D1 DA receptor, triggering the cytosolic retention of p-ERK and inducing striatal neuronal apoptotic death. These data provide unique insight into a novel role of p-ERK in striatal neurodegeneration. PMID:19200235

  7. Gadolinium-enhanced magnetic resonance angiography in brain death

    NASA Astrophysics Data System (ADS)

    Luchtmann, M.; Beuing, O.; Skalej, M.; Kohl, J.; Serowy, S.; Bernarding, J.; Firsching, R.

    2014-01-01

    Confirmatory tests for the diagnosis of brain death in addition to clinical findings may shorten observation time required in some countries and may add certainty to the diagnosis under specific circumstances. The practicability of Gadolinium-enhanced magnetic resonance angiography to confirm cerebral circulatory arrest was assessed after the diagnosis of brain death in 15 patients using a 1.5 Tesla MRI scanner. In all 15 patients extracranial blood flow distal to the external carotid arteries was undisturbed. In 14 patients no contrast medium was noted within intracerebral vessels above the proximal level of the intracerebral arteries. In one patient more distal segments of the anterior and middle cerebral arteries (A3 and M3) were filled with contrast medium. Gadolinium-enhanced MRA may be considered conclusive evidence of cerebral circulatory arrest, when major intracranial vessels fail to fill with contrast medium while extracranial vessels show normal blood flow.

  8. Endoplasmic Reticulum Stress Signaling in Plant Immunity—At the Crossroad of Life and Death

    PubMed Central

    Kørner, Camilla J.; Du, Xinran; Vollmer, Marie E.; Pajerowska-Mukhtar, Karolina M.

    2015-01-01

    Rapid and complex immune responses are induced in plants upon pathogen recognition. One form of plant defense response is a programmed burst in transcription and translation of pathogenesis-related proteins, of which many rely on ER processing. Interestingly, several ER stress marker genes are up-regulated during early stages of immune responses, suggesting that enhanced ER capacity is needed for immunity. Eukaryotic cells respond to ER stress through conserved signaling networks initiated by specific ER stress sensors tethered to the ER membrane. Depending on the nature of ER stress the cell prioritizes either survival or initiates programmed cell death (PCD). At present two plant ER stress sensors, bZIP28 and IRE1, have been described. Both sensor proteins are involved in ER stress-induced signaling, but only IRE1 has been additionally linked to immunity. A second branch of immune responses relies on PCD. In mammals, ER stress sensors are involved in activation of PCD, but it is unclear if plant ER stress sensors play a role in PCD. Nevertheless, some ER resident proteins have been linked to pathogen-induced cell death in plants. In this review, we will discuss the current understanding of plant ER stress signaling and its cross-talk with immune signaling. PMID:26556351

  9. Enhancement Of Optical Registration Signals Through Digital Signal Processing Techniques

    NASA Astrophysics Data System (ADS)

    Cote, Daniel R.; Lazo-Wasem, Jeanne

    1988-01-01

    Alignment and setup of lighography processes has largely been conducted on special test wafers. Actual product level optimization has been limited to manual techniques such as optical verniers. This is especially time consuming and prone to inconsistencies when the registration characteristics of lithographic systems are being measured. One key factor obstructing the use of automated metrology equipment on product level wafers is the inability to discern reliably, metrology features from the background noise and variations in optical registration signals. This is often the case for metal levels such as aluminum and tungsten. This paper discusses methods for enhancement of typical registration signals obtained from difficult semiconductor process levels. Brightfield and darkfield registration signals are obtained using a microscope and a 1024 element linear photodiode array. These signals are then digitized and stored on the hard disk of a computer. The techniques utilized include amplitude selective and adaptive and non-adaptive frequency domain filtering techniques. The effect of each of these techniques upon calculated registration values is analyzed by determining the positional variation of the center location of a two line registration feature. Plots of raw and processed signals obtained are presented as are plots of the power spectral density of ideal metrology feature signal and noise patterns. It is concluded that the proper application of digital signal processing (DSP) techniques to problematic optical registration signals greatly enhances the applicability of automated optical registration measurement techniques to difficult semiconductor process levels.

  10. Tyramide Signal Amplification for Immunofluorescent Enhancement.

    PubMed

    Faget, Lauren; Hnasko, Thomas S

    2015-01-01

    Enzyme-linked signal amplification is a key technique used to enhance the immunohistochemical detection of protein, mRNA, and other molecular species. Tyramide signal amplification (TSA) is based on a catalytic reporter deposit in close vicinity to the epitope of interest. The advantages of this technique are its simplicity, enhanced sensitivity, high specificity, and compatibility with modern multi-label fluorescent microscopy. Here, we describe the use of a TSA kit to increase the signal of enhanced green fluorescent protein (eGFP) expressed under the control of Slc17a6 regulatory elements in the brain of a transgenic mouse. The labeling procedure consists of 6 basic steps: (1) tissue preparation, (2) blocking of nonspecific epitopes, (3) binding with primary antibody, (4) binding with horseradish peroxidase-conjugated secondary antibody, (5) reacting with fluorescent tyramide substrate, and (6) imaging of the signal. The procedures described herein detail these steps and provide additional guidance and background to assist novice users.

  11. Relationship Between Pak-Mediated Cell Death and Stress-Activated Kinase Signaling in Breast Cancer

    DTIC Science & Technology

    2000-02-01

    part of the cell death execution machinery. Here we show that a correlation exists in breast cancer cells between caspase- dependent cleavage of the...inhibits its activity might allow us to specifically inhibit signaling pathways downstream of Pak and evaluate how the cell death process is affected. In...a biochemical approach screening for substrates and possible mediators of cell death signaling components via Pak kinases we identified a guanine

  12. The canonical Wg signaling modulates Bsk-mediated cell death in Drosophila

    PubMed Central

    Zhang, S; Chen, C; Wu, C; Yang, Y; Li, W; Xue, L

    2015-01-01

    Cell death is an essential regulatory mechanism for removing unneeded cells in animal development and tissue homeostasis. The c-Jun N-terminal kinase (JNK) pathway has pivotal roles in the regulation of cell death in response to various intrinsic and extrinsic stress signals. The canonical Wingless (Wg) signaling has been implicated in cell proliferation and cell fate decisions, whereas its role in cell death remains largely elusive. Here, we report that activated Bsk (the Drosophila JNK homolog) induced cell death is mediated by the canonical Wg signaling. First, loss of Wg signaling abrogates Bsk-mediated caspase-independent cell death. Second, activation of Wg signaling promotes cell death in a caspase-independent manner. Third, activation of Bsk signaling results in upregulated transcription of wingless (wg) gene. Finally, Wg pathway participates in the physiological function of Bsk signaling in development. These findings not only reveal a previously undiscovered role of Wg signaling in Bsk-mediated cell death, but also provide a novel mechanism for the interplay between the two important signaling pathways in development. PMID:25855961

  13. Disruption of glycolytic flux is a signal for inflammasome signaling and pyroptotic cell death

    PubMed Central

    Sanman, Laura E; Qian, Yu; Eisele, Nicholas A; Ng, Tessie M; van der Linden, Wouter A; Monack, Denise M; Weerapana, Eranthie; Bogyo, Matthew

    2016-01-01

    When innate immune cells such as macrophages are challenged with environmental stresses or infection by pathogens, they trigger the rapid assembly of multi-protein complexes called inflammasomes that are responsible for initiating pro-inflammatory responses and a form of cell death termed pyroptosis. We describe here the identification of an intracellular trigger of NLRP3-mediated inflammatory signaling, IL-1β production and pyroptosis in primed murine bone marrow-derived macrophages that is mediated by the disruption of glycolytic flux. This signal results from a drop of NADH levels and induction of mitochondrial ROS production and can be rescued by addition of products that restore NADH production. This signal is also important for host-cell response to the intracellular pathogen Salmonella typhimurium, which can disrupt metabolism by uptake of host-cell glucose. These results reveal an important inflammatory signaling network used by immune cells to sense metabolic dysfunction or infection by intracellular pathogens. DOI: http://dx.doi.org/10.7554/eLife.13663.001 PMID:27011353

  14. The proinflammatory cytokine interleukin-18 alters multiple signaling pathways to inhibit natural killer cell death

    USGS Publications Warehouse

    Hodge, D.L.; Subleski, J.J.; Reynolds, D.A.; Buschman, M.D.; Schill, W.B.; Burkett, M.W.; Malyguine, A.M.; Young, H.A.

    2006-01-01

    The proinflammatory cytokine, interleukin-18 (IL-18), is a natural killer (NK) cell activator that induces NK cell cytotoxicity and interferon-?? (IFN-??) expression. In this report, we define a novel role for IL-18 as an NK cell protective agent. Specifically, IL-18 prevents NK cell death initiated by different and distinct stress mechanisms. IL-18 reduces NK cell self-destruction during NK-targeted cell killing, and in the presence of staurosporin, a potent apoptotic inducer, IL-18 reduces caspase-3 activity. The critical regulatory step in this process is downstream of the mitochondrion and involves reduced cleavage and activation of caspase-9 and caspase-3. The ability of IL-18 to regulate cell survival is not limited to a caspase death pathway in that IL-18 augments tumor necrosis factor (TNF) signaling, resulting in increased and prolonged mRNA expression of c-apoptosis inhibitor 2 (cIAP2), a prosurvival factor and caspase-3 inhibitor, and TNF receptor-associated factor 1 (TRAF1), a prosurvival protein. The cumulative effects of IL-18 define a novel role for this cytokine as a molecular survival switch that functions to both decrease cell death through inhibition of the mitochondrial apoptotic pathway and enhance TNF induction of prosurvival factors. ?? Mary Ann Liebert, Inc.

  15. Enhanced Propagating Surface Plasmon Signal Detection

    SciTech Connect

    Gong, Y.; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.

    2016-12-21

    Overcoming the dissipative nature of propagating surface plasmons (PSPs) is pre-requisite to realizing functional plasmonic circuitry, in which large bandwidth signals can be manipulated over length scales far-below the diffraction limit of light. To this end, we report on a novel PSP enhanced signal detection technique achieved in an all-metallic substrate. We take advantage of two strategically spatio-temporally separated phase-locked femtosecond laser pulses, incident onto lithographically patterned PSP coupling structures. We follow PSP propagation with joint femtosecond temporal and nanometer spatial resolution in a time-resolved non-linear photoemission electron microscopy scheme. Initially, a PSP signal wave packet is launched from a hole etched into the silver surface from where it propagates through an open trench structure and is decoded through the use of a timed probe pulse. FDTD calculations demonstrate that PSP signal waves may traverse open trenches in excess of 10 microns in diameter, thereby allowing remote detection even through vacuum regions. This arrangement results in a 10X enhancement in photoemission relative to readout from the bare metal surface. The enhancement is attributed to an all-optical homodyne detection technique that mixes signal and reference PSP waves in a non-linear scheme. Larger readout trenches achieve higher readout levels, however reduced transmission through the trench limits the trench size to 6 microns for maximum readout levels. However, the use of an array of trenches increases the maximum enhancement to near 30X. The attainable enhancement factor may be harnessed to achieve extended coherent PSP propagation in ultrafast plasmonic circuitry.

  16. Calcium signaling as a mediator of cell energy demand and a trigger to cell death

    PubMed Central

    Bhosale, Gauri; Sharpe, Jenny A.; Sundier, Stephanie Y.

    2015-01-01

    Calcium signaling is pivotal to a host of physiological pathways. A rise in calcium concentration almost invariably signals an increased cellular energy demand. Consistent with this, calcium signals mediate a number of pathways that together serve to balance energy supply and demand. In pathological states, calcium signals can precipitate mitochondrial injury and cell death, especially when coupled to energy depletion and oxidative or nitrosative stress. This review explores the mechanisms that couple cell signaling pathways to metabolic regulation or to cell death. The significance of these pathways is exemplified by pathological case studies, such as those showing loss of mitochondrial calcium uptake 1 in patients and ischemia/reperfusion injury. PMID:26375864

  17. Ethylene signaling in salt stress- and salicylic acid-induced programmed cell death in tomato suspension cells.

    PubMed

    Poór, Péter; Kovács, Judit; Szopkó, Dóra; Tari, Irma

    2013-02-01

    Salt stress- and salicylic acid (SA)-induced cell death can be activated by various signaling pathways including ethylene (ET) signaling in intact tomato plants. In tomato suspension cultures, a treatment with 250 mM NaCl increased the production of reactive oxygen species (ROS), nitric oxide (NO), and ET. The 10(-3) M SA-induced cell death was also accompanied by ROS and NO production, but ET emanation, the most characteristic difference between the two cell death programs, did not change. ET synthesis was enhanced by addition of ET precursor 1-aminocyclopropane-1-carboxylic acid, which, after 2 h, increased the ROS production in the case of both stressors and accelerated cell death under salt stress. However, it did not change the viability and NO levels in SA-treated samples. The effect of ET induced by salt stress could be blocked with silver thiosulfate (STS), an inhibitor of ET action. STS reduced the death of cells which is in accordance with the decrease in ROS production of cells exposed to high salinity. Unexpectedly, application of STS together with SA resulted in increasing ROS and reduced NO accumulation which led to a faster cell death. NaCl- and SA-induced cell death was blocked by Ca(2+) chelator EGTA and calmodulin inhibitor W-7, or with the inhibitors of ROS. The inhibitor of MAPKs, PD98059, and the cysteine protease inhibitor E-64 reduced cell death in both cases. These results show that NaCl induces cell death mainly by ET-induced ROS production, but ROS generated by SA was not controlled by ET in tomato cell suspension.

  18. The Fas-FADD Death Domain Complex Structure Unravels Signalling by Receptor Clustering

    SciTech Connect

    Scott, F.; Stec, B; Pop, C; Dobaczewska, M; Lee, J; Monosov, E; Robinson, H; Salvesen, G; Schwarzenbacher, R; Riedl, S

    2009-01-01

    The death inducing signalling complex (DISC) formed by Fas receptor, FADD (Fas-associated death domain protein) and caspase 8 is a pivotal trigger of apoptosis1, 2, 3. The Fas-FADD DISC represents a receptor platform, which once assembled initiates the induction of programmed cell death. A highly oligomeric network of homotypic protein interactions comprised of the death domains of Fas and FADD is at the centre of DISC formation4, 5. Thus, characterizing the mechanistic basis for the Fas-FADD interaction is crucial for understanding DISC signalling but has remained unclear largely because of a lack of structural data. We have successfully formed and isolated the human Fas-FADD death domain complex and report the 2.7 A crystal structure. The complex shows a tetrameric arrangement of four FADD death domains bound to four Fas death domains. We show that an opening of the Fas death domain exposes the FADD binding site and simultaneously generates a Fas-Fas bridge. The result is a regulatory Fas-FADD complex bridge governed by weak protein-protein interactions revealing a model where the complex itself functions as a mechanistic switch. This switch prevents accidental DISC assembly, yet allows for highly processive DISC formation and clustering upon a sufficient stimulus. In addition to depicting a previously unknown mode of death domain interactions, these results further uncover a mechanism for receptor signalling solely by oligomerization and clustering events.

  19. Targeted Lymphoma Cell Death by Novel Signal Transduction Modifications

    DTIC Science & Technology

    2010-07-14

    AD_________________ Award Number: W81XWH-07-1-0471 TITLE: Targeted Lymphoma Cell Death by Novel...opinions and/or findings contained in this report are those of the author( s ) and should not be construed as an official Department of the Army position...ADDRESS. 1. REPORT DATE 14-07-2010 2. REPORT TYPE Annual 3. DATES COVERED 15 JUN 2009 - 14 JUN 2010 4. TITLE AND SUBTITLE Targeted Lymphoma Cell

  20. Regulation of cell death receptor S-nitrosylation and apoptotic signaling by Sorafenib in hepatoblastoma cells☆

    PubMed Central

    Rodríguez-Hernández, A.; Navarro-Villarán, E.; González, R.; Pereira, S.; Soriano-De Castro, L.B.; Sarrias-Giménez, A.; Barrera-Pulido, L.; Álamo-Martínez, J.M.; Serrablo-Requejo, A.; Blanco-Fernández, G.; Nogales-Muñoz, A.; Gila-Bohórquez, A.; Pacheco, D.; Torres-Nieto, M.A.; Serrano-Díaz-Canedo, J.; Suárez-Artacho, G.; Bernal-Bellido, C.; Marín-Gómez, L.M.; Barcena, J.A.; Gómez-Bravo, M.A.; Padilla, C.A.; Padillo, F.J.; Muntané, J.

    2015-01-01

    Nitric oxide (NO) plays a relevant role during cell death regulation in tumor cells. The overexpression of nitric oxide synthase type III (NOS-3) induces oxidative and nitrosative stress, p53 and cell death receptor expression and apoptosis in hepatoblastoma cells. S-nitrosylation of cell death receptor modulates apoptosis. Sorafenib is the unique recommended molecular-targeted drug for the treatment of patients with advanced hepatocellular carcinoma. The present study was addressed to elucidate the potential role of NO during Sorafenib-induced cell death in HepG2 cells. We determined the intra- and extracellular NO concentration, cell death receptor expression and their S-nitrosylation modifications, and apoptotic signaling in Sorafenib-treated HepG2 cells. The effect of NO donors on above parameters has also been determined. Sorafenib induced apoptosis in HepG2 cells. However, low concentration of the drug (10 nM) increased cell death receptor expression, as well as caspase-8 and -9 activation, but without activation of downstream apoptotic markers. In contrast, Sorafenib (10 µM) reduced upstream apoptotic parameters but increased caspase-3 activation and DNA fragmentation in HepG2 cells. The shift of cell death signaling pathway was associated with a reduction of S-nitrosylation of cell death receptors in Sorafenib-treated cells. The administration of NO donors increased S-nitrosylation of cell death receptors and overall induction of cell death markers in control and Sorafenib-treated cells. In conclusion, Sorafenib induced alteration of cell death receptor S-nitrosylation status which may have a relevant repercussion on cell death signaling in hepatoblastoma cells. PMID:26233703

  1. Regulation of cell death receptor S-nitrosylation and apoptotic signaling by Sorafenib in hepatoblastoma cells.

    PubMed

    Rodríguez-Hernández, A; Navarro-Villarán, E; González, R; Pereira, S; Soriano-De Castro, L B; Sarrias-Giménez, A; Barrera-Pulido, L; Álamo-Martínez, J M; Serrablo-Requejo, A; Blanco-Fernández, G; Nogales-Muñoz, A; Gila-Bohórquez, A; Pacheco, D; Torres-Nieto, M A; Serrano-Díaz-Canedo, J; Suárez-Artacho, G; Bernal-Bellido, C; Marín-Gómez, L M; Barcena, J A; Gómez-Bravo, M A; Padilla, C A; Padillo, F J; Muntané, J

    2015-12-01

    Nitric oxide (NO) plays a relevant role during cell death regulation in tumor cells. The overexpression of nitric oxide synthase type III (NOS-3) induces oxidative and nitrosative stress, p53 and cell death receptor expression and apoptosis in hepatoblastoma cells. S-nitrosylation of cell death receptor modulates apoptosis. Sorafenib is the unique recommended molecular-targeted drug for the treatment of patients with advanced hepatocellular carcinoma. The present study was addressed to elucidate the potential role of NO during Sorafenib-induced cell death in HepG2 cells. We determined the intra- and extracellular NO concentration, cell death receptor expression and their S-nitrosylation modifications, and apoptotic signaling in Sorafenib-treated HepG2 cells. The effect of NO donors on above parameters has also been determined. Sorafenib induced apoptosis in HepG2 cells. However, low concentration of the drug (10nM) increased cell death receptor expression, as well as caspase-8 and -9 activation, but without activation of downstream apoptotic markers. In contrast, Sorafenib (10 µM) reduced upstream apoptotic parameters but increased caspase-3 activation and DNA fragmentation in HepG2 cells. The shift of cell death signaling pathway was associated with a reduction of S-nitrosylation of cell death receptors in Sorafenib-treated cells. The administration of NO donors increased S-nitrosylation of cell death receptors and overall induction of cell death markers in control and Sorafenib-treated cells. In conclusion, Sorafenib induced alteration of cell death receptor S-nitrosylation status which may have a relevant repercussion on cell death signaling in hepatoblastoma cells.

  2. Cleavage of Signal Regulatory Protein α (SIRPα) Enhances Inflammatory Signaling.

    PubMed

    Londino, James D; Gulick, Dexter; Isenberg, Jeffrey S; Mallampalli, Rama K

    2015-12-25

    Signal regulatory protein α (SIRPα) is a membrane glycoprotein immunoreceptor abundant in cells of monocyte lineage. SIRPα ligation by a broadly expressed transmembrane protein, CD47, results in phosphorylation of the cytoplasmic immunoreceptor tyrosine-based inhibitory motifs, resulting in the inhibition of NF-κB signaling in macrophages. Here we observed that proteolysis of SIRPα during inflammation is regulated by a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), resulting in the generation of a membrane-associated cleavage fragment in both THP-1 monocytes and human lung epithelia. We mapped a charge-dependent putative cleavage site near the membrane-proximal domain necessary for ADAM10-mediated cleavage. In addition, a secondary proteolytic cleavage within the membrane-associated SIRPα fragment by γ-secretase was identified. Ectopic expression of a SIRPα mutant plasmid encoding a proteolytically resistant form in HeLa cells inhibited activation of the NF-κB pathway and suppressed STAT1 phosphorylation in response to TNFα to a greater extent than expression of wild-type SIRPα. Conversely, overexpression of plasmids encoding the proteolytically cleaved SIRPα fragments in cells resulted in enhanced STAT-1 and NF-κB pathway activation. Thus, the data suggest that combinatorial actions of ADAM10 and γ-secretase on SIRPα cleavage promote inflammatory signaling.

  3. Cleavage of Signal Regulatory Protein α (SIRPα) Enhances Inflammatory Signaling*

    PubMed Central

    Londino, James D.; Gulick, Dexter; Isenberg, Jeffrey S.; Mallampalli, Rama K.

    2015-01-01

    Signal regulatory protein α (SIRPα) is a membrane glycoprotein immunoreceptor abundant in cells of monocyte lineage. SIRPα ligation by a broadly expressed transmembrane protein, CD47, results in phosphorylation of the cytoplasmic immunoreceptor tyrosine-based inhibitory motifs, resulting in the inhibition of NF-κB signaling in macrophages. Here we observed that proteolysis of SIRPα during inflammation is regulated by a disintegrin and metalloproteinase domain-containing protein 10 (ADAM10), resulting in the generation of a membrane-associated cleavage fragment in both THP-1 monocytes and human lung epithelia. We mapped a charge-dependent putative cleavage site near the membrane-proximal domain necessary for ADAM10-mediated cleavage. In addition, a secondary proteolytic cleavage within the membrane-associated SIRPα fragment by γ-secretase was identified. Ectopic expression of a SIRPα mutant plasmid encoding a proteolytically resistant form in HeLa cells inhibited activation of the NF-κB pathway and suppressed STAT1 phosphorylation in response to TNFα to a greater extent than expression of wild-type SIRPα. Conversely, overexpression of plasmids encoding the proteolytically cleaved SIRPα fragments in cells resulted in enhanced STAT-1 and NF-κB pathway activation. Thus, the data suggest that combinatorial actions of ADAM10 and γ-secretase on SIRPα cleavage promote inflammatory signaling. PMID:26534964

  4. Neuronal death enhanced by N-methyl-d-aspartate antagonists

    PubMed Central

    Ikonomidou, Chrysanthy; Stefovska, Vanya; Turski, Lechoslaw

    2000-01-01

    Glutamate promotes neuronal survival during brain development and destroys neurons after injuries in the mature brain. Glutamate antagonists are in human clinical trials aiming to demonstrate limitation of neuronal injury after head trauma, which consists of both rapid and slowly progressing neurodegeneration. Furthermore, glutamate antagonists are considered for neuroprotection in chronic neurodegenerative disorders with slowly progressing cell death only. Therefore, humans suffering from Huntington's disease, characterized by slowly progressing neurodegeneration of the basal ganglia, are subjected to trials with glutamate antagonists. Here we demonstrate that progressive neurodegeneration in the basal ganglia induced by the mitochondrial toxin 3-nitropropionate or in the hippocampus by traumatic brain injury is enhanced by N-methyl-d-aspartate antagonists but ameliorated by α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate antagonists. These observations reveal that N-methyl-d-aspartate antagonists may increase neurodestruction in mature brain undergoing slowly progressing neurodegeneration, whereas blockade of the action of glutamate at α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate receptors may be neuroprotective. PMID:11058158

  5. Altered Death Receptor Signaling Promotes Epithelial-to-Mesenchymal Transition and Acquired Chemoresistance

    PubMed Central

    Antoon, James W.; Lai, Rongye; Struckhoff, Amanda P.; Nitschke, Ashley M.; Elliott, Steven; Martin, Elizabeth C.; Rhodes, Lyndsay V.; Yoon, Nam Seung; Salvo, Virgilio A.; Shan, Bin; Beckman, Barbara S.; Nephew, Kenneth P.; Burow, Matthew E.

    2012-01-01

    Altered death receptor signaling and resistance to subsequent apoptosis is an important clinical resistance mechanism. Here, we investigated the role of death receptor resistance in breast cancer progression. Resistance of the estrogen receptor alpha (ER)-positive, chemosensitive MCF7 breast cancer cell line to tumor necrosis factor (TNF) was associated with loss of ER expression and a multi-drug resistant phenotype. Changes in three major pathways were involved in this transition to a multidrug resistance phenotype: ER, Death Receptor and epithelial to mesenchymal transition (EMT). Resistant cells exhibited altered ER signaling, resulting in decreased ER target gene expression. The death receptor pathway was significantly altered, blocking extrinsic apoptosis and increasing NF-kappaB survival signaling. TNF resistance promoted EMT changes, resulting in a more aggressive phenotype. This first report identifying specific mechanisms underlying acquired resistance to TNF could lead to a better understanding of the progression of breast cancer in response to chemotherapy treatment. PMID:22844580

  6. Enhancing the antitumor efficacy of a cell-surface death ligand by covalent membrane display.

    PubMed

    Nair, Pradeep M; Flores, Heather; Gogineni, Alvin; Marsters, Scot; Lawrence, David A; Kelley, Robert F; Ngu, Hai; Sagolla, Meredith; Komuves, Laszlo; Bourgon, Richard; Settleman, Jeffrey; Ashkenazi, Avi

    2015-05-05

    TNF superfamily death ligands are expressed on the surface of immune cells and can trigger apoptosis in susceptible cancer cells by engaging cognate death receptors. A recombinant soluble protein comprising the ectodomain of Apo2 ligand/TNF-related apoptosis-inducing ligand (Apo2L/TRAIL) has shown remarkable preclinical anticancer activity but lacked broad efficacy in patients, possibly owing to insufficient exposure or potency. We observed that antibody cross-linking substantially enhanced cytotoxicity of soluble Apo2L/TRAIL against diverse cancer cell lines. Presentation of the ligand on glass-supported lipid bilayers enhanced its ability to drive receptor microclustering and apoptotic signaling. Furthermore, covalent surface attachment of Apo2L/TRAIL onto liposomes--synthetic lipid-bilayer nanospheres--similarly augmented activity. In vivo, liposome-displayed Apo2L/TRAIL achieved markedly better exposure and antitumor activity. Thus, covalent synthetic-membrane attachment of a cell-surface ligand enhances efficacy, increasing therapeutic potential. These findings have translational implications for liposomal approaches as well as for Apo2L/TRAIL and other clinically relevant TNF ligands.

  7. Enhancement of Death Acceptance by a Grief Counseling Course.

    ERIC Educational Resources Information Center

    Irwin, Harvey J.; Melbin-Helberg, Elizabeth B.

    1992-01-01

    Investigated impact of grief counseling course in terms of two-component formulation of death acceptance. Compared to controls, participants showed significant and sustained increase in cognitive confrontation of death and in assimilation of attitudes at emotional level. Identified predictors of extent of effect included individual's initial death…

  8. Ras Homolog Enriched in Brain (Rheb) Enhances Apoptotic Signaling*

    PubMed Central

    Karassek, Sascha; Berghaus, Carsten; Schwarten, Melanie; Goemans, Christoph G.; Ohse, Nadine; Kock, Gerd; Jockers, Katharina; Neumann, Sebastian; Gottfried, Sebastian; Herrmann, Christian; Heumann, Rolf; Stoll, Raphael

    2010-01-01

    Rheb is a homolog of Ras GTPase that regulates cell growth, proliferation, and regeneration via mammalian target of rapamycin (mTOR). Because of the well established potential of activated Ras to promote survival, we sought to investigate the ability of Rheb signaling to phenocopy Ras. We found that overexpression of lipid-anchored Rheb enhanced the apoptotic effects induced by UV light, TNFα, or tunicamycin in an mTOR complex 1 (mTORC1)-dependent manner. Knocking down endogenous Rheb or applying rapamycin led to partial protection, identifying Rheb as a mediator of cell death. Ras and c-Raf kinase opposed the apoptotic effects induced by UV light or TNFα but did not prevent Rheb-mediated apoptosis. To gain structural insight into the signaling mechanisms, we determined the structure of Rheb-GDP by NMR. The complex adopts the typical canonical fold of RasGTPases and displays the characteristic GDP-dependent picosecond to nanosecond backbone dynamics of the switch I and switch II regions. NMR revealed Ras effector-like binding of activated Rheb to the c-Raf-Ras-binding domain (RBD), but the affinity was 1000-fold lower than the Ras/RBD interaction, suggesting a lack of functional interaction. shRNA-mediated knockdown of apoptosis signal-regulating kinase 1 (ASK-1) strongly reduced UV or TNFα-induced apoptosis and suppressed enhancement by Rheb overexpression. In conclusion, Rheb-mTOR activation not only promotes normal cell growth but also enhances apoptosis in response to diverse toxic stimuli via an ASK-1-mediated mechanism. Pharmacological regulation of the Rheb/mTORC1 pathway using rapamycin should take the presence of cellular stress into consideration, as this may have clinical implications. PMID:20685651

  9. TAK1 regulates caspase 8 activation and necroptotic signaling via multiple cell death checkpoints

    PubMed Central

    Guo, Xiaoyun; Yin, Haifeng; Chen, Yi; Li, Lei; Li, Jing; Liu, Qinghang

    2016-01-01

    Necroptosis has emerged as a new form of programmed cell death implicated in a number of pathological conditions such as ischemic injury, neurodegenerative disease, and viral infection. Recent studies indicate that TGFβ-activated kinase 1 (TAK1) is nodal regulator of necroptotic cell death, although the underlying molecular regulatory mechanisms are not well defined. Here we reported that TAK1 regulates necroptotic signaling as well as caspase 8-mediated apoptotic signaling through both NFκB-dependent and -independent mechanisms. Inhibition of TAK1 promoted TNFα-induced cell death through the induction of RIP1 phosphorylation/activation and necrosome formation. Further, inhibition of TAK1 triggered two caspase 8 activation pathways through the induction of RIP1-FADD-caspase 8 complex as well as FLIP cleavage/degradation. Mechanistically, our data uncovered an essential role for the adaptor protein TNF receptor-associated protein with death domain (TRADD) in caspase 8 activation and necrosome formation triggered by TAK1 inhibition. Moreover, ablation of the deubiqutinase CYLD prevented both apoptotic and necroptotic signaling induced by TAK1 inhibition. Finally, blocking the ubiquitin-proteasome pathway prevented the degradation of key pro-survival signaling proteins and necrosome formation. Thus, we identified new regulatory mechanisms underlying the critical role of TAK1 in cell survival through regulation of multiple cell death checkpoints. Targeting key components of the necroptotic pathway (e.g., TRADD and CYLD) and the ubiquitin-proteasome pathway may represent novel therapeutic strategies for pathological conditions driven by necroptosis. PMID:27685625

  10. Signal enhancement using a switchable magnetic trap

    DOEpatents

    Beer, Neil Reginald [Pleasanton, CA

    2012-05-29

    A system for analyzing a sample including providing a microchannel flow channel; associating the sample with magnetic nanoparticles or magnetic polystyrene-coated beads; moving the sample with said magnetic nanoparticles or magnetic polystyrene-coated beads in the microchannel flow channel; holding the sample with the magnetic nanoparticles or magnetic polystyrene-coated beads in a magnetic trap in the microchannel flow channel; and analyzing the sample obtaining an enhanced analysis signal. An apparatus for analysis of a sample includes magnetic particles connected to the sample, a microchip, a flow channel in the microchip, a source of carrier fluid connected to the flow channel for moving the sample in the flow channel, an electromagnet trap connected to the flow line for selectively magnetically trapping the sample and the magnetic particles, and an analyzer for analyzing the sample.

  11. Radar range data signal enhancement tracker

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The design, fabrication, and performance characteristics are described of two digital data signal enhancement filters which are capable of being inserted between the Space Shuttle Navigation Sensor outputs and the guidance computer. Commonality of interfaces has been stressed so that the filters may be evaluated through operation with simulated sensors or with actual prototype sensor hardware. The filters will provide both a smoothed range and range rate output. Different conceptual approaches are utilized for each filter. The first filter is based on a combination low pass nonrecursive filter and a cascaded simple average smoother for range and range rate, respectively. Filter number two is a tracking filter which is capable of following transient data of the type encountered during burn periods. A test simulator was also designed which generates typical shuttle navigation sensor data.

  12. Two Adjacent Trimeric Fas Ligands Are Required for Fas Signaling and Formation of a Death-Inducing Signaling Complex

    PubMed Central

    Holler, Nils; Tardivel, Aubry; Kovacsovics-Bankowski, Magdalena; Hertig, Sylvie; Gaide, Olivier; Martinon, Fabio; Tinel, Antoine; Deperthes, David; Calderara, Silvio; Schulthess, Therese; Engel, Jürgen; Schneider, Pascal; Tschopp, Jürg

    2003-01-01

    The membrane-bound form of Fas ligand (FasL) signals apoptosis in target cells through engagement of the death receptor Fas, whereas the proteolytically processed, soluble form of FasL does not induce cell death. However, soluble FasL can be rendered active upon cross-linking. Since the minimal extent of oligomerization of FasL that exerts cytotoxicity is unknown, we engineered hexameric proteins containing two trimers of FasL within the same molecule. This was achieved by fusing FasL to the Fc portion of immunoglobulin G1 or to the collagen domain of ACRP30/adiponectin. Trimeric FasL and hexameric FasL both bound to Fas, but only the hexameric forms were highly cytotoxic and competent to signal apoptosis via formation of a death-inducing signaling complex. Three sequential early events in Fas-mediated apoptosis could be dissected, namely, receptor binding, receptor activation, and recruitment of intracellular signaling molecules, each of which occurred independently of the subsequent one. These results demonstrate that the limited oligomerization of FasL, and most likely of some other tumor necrosis factor family ligands such as CD40L, is required for triggering of the signaling pathways. PMID:12556501

  13. Partial equilibrium approximations in apoptosis. II. The death-inducing signaling complex subsystem.

    PubMed

    Huang, Ya-Jing; Hong, Liu; Yong, Wen-An

    2015-12-01

    This paper is a continuation of our previous work (Huang and Yong, 2013) for simplifying the Fas signaling-induced apoptotic pathway identified by Hua et al. (2005) for human tumor T cells. The previous paper studied the downstream intracelluar-signaling subsystem, while the present one is concerned with the upstream death-inducing signaling complex (DISC) subsystem. Under the assumption that the bind of Fas-associated death domains and FLICE-inhibitory proteins to the DISC is much faster than that of the initiator procaspases, we greatly simplify the upstream subsystem from 35 reactions with 26 species to 6 reactions with 9 species by adopting the classical and recently justified partial equilibrium approximation method. Numerical simulations show that the simplified model is in an excellent agreement with the original model. Most importantly, the simplified model clearly reveals the key reactants and dominated pathways in the Fas signaling process, and thus provides new insights into the apoptosis.

  14. HYAL-2–WWOX–SMAD4 Signaling in Cell Death and Anticancer Response

    PubMed Central

    Hsu, Li-Jin; Chiang, Ming-Fu; Sze, Chun-I; Su, Wan-Pei; Yap, Ye Vone; Lee, I-Ting; Kuo, Hsiang-Ling; Chang, Nan-Shan

    2016-01-01

    Hyaluronidase HYAL-2 is a membrane-anchored protein and also localizes, in part, in the lysosome. Recent study from animal models revealed that both HYAL-1 and HYAL-2 are essential for the metabolism of hyaluronan (HA). Hyal-2 deficiency is associated with chronic thrombotic microangiopathy with hemolytic anemia in mice due to over accumulation of high molecular size HA. HYAL-2 is essential for platelet generation. Membrane HYAL-2 degrades HA bound by co-receptor CD44. Also, in a non-canonical signal pathway, HYAL-2 serves as a receptor for transforming growth factor beta (TGF-β) to signal with downstream tumor suppressors WWOX and SMAD4 to control gene transcription. When SMAD4 responsive element is overly driven by the HYAL-2–WWOX–SMAD4 signaling complex, cell death occurs. When rats are subjected to traumatic brain injury, over accumulation of a HYAL-2–WWOX complex occurs in the nucleus to cause neuronal death. HA induces the signaling of HYAL-2–WWOX–SMAD4 and relocation of the signaling complex to the nucleus. If the signaling complex is overexpressed, bubbling cell death occurs in WWOX-expressing cells. In addition, a small synthetic peptide Zfra (zinc finger-like protein that regulates apoptosis) binds membrane HYAL-2 of non-T/non-B spleen HYAL-2+ CD3− CD19− Z lymphocytes and activates the cells to generate memory anticancer response against many types of cancer cells in vivo. Whether the HYAL-2–WWOX–SMAD4 signaling complex is involved is discussed. In this review and opinion article, we have updated the current knowledge of HA, HYAL-2 and WWOX, HYAL-2–WWOX–SMAD4 signaling, bubbling cell death, and Z cell activation for memory anticancer response. PMID:27999774

  15. A type III effector antagonises death receptor signalling during bacterial gut infection

    PubMed Central

    Pearson, Jaclyn S; Giogha, Cristina; Ong, Sze Ying; Kennedy, Catherine L; Kelly, Michelle; Robinson, Keith S; Wong, Tania; Mansell, Ashley; Riedmaier, Patrice; Oates, Clare VL; Zaid, Ali; Mühlen, Sabrina; Crepin, Valerie F; Marches, Olivier; Ang, Ching-Seng; Williamson, Nicholas A; O’Reilly, Lorraine A; Bankovacki, Aleksandra; Nachbur, Ueli; Infusini, Giuseppe; Webb, Andrew I; Silke, John; Strasser, Andreas; Frankel, Gad; Hartland, Elizabeth L

    2013-01-01

    Successful infection by enteric bacterial pathogens depends on the ability of the bacteria to colonise the gut, replicate in host tissues and disseminate to other hosts. Pathogens such as Salmonella, Shigella and enteropathogenic and enterohaemorrhagic E. coli (EPEC and EHEC), utilise a type III secretion system (T3SS) to deliver virulence effector proteins into host cells during infection that promote colonisation and interfere with antimicrobial host responses 1-3. Here we report that the T3SS effector NleB1 from EPEC binds to host cell death domain containing proteins and thereby inhibits death receptor signalling. Protein interaction studies identified FADD, TRADD and RIPK1 as binding partners of NleB1. NleB1 expressed ectopically or injected by the bacterial T3SS prevented Fas ligand or TNF-induced formation of the canonical death inducing signalling complex (DISC) and proteolytic activation of caspase-8, an essential step in death receptor induced apoptosis. This inhibition depended on the N-GlcNAc transferase activity of NleB1, which specifically modified Arg117 in the death domain of FADD. The importance of the death receptor apoptotic pathway to host defence was demonstrated using mice deficient in the FAS signalling pathway, which showed delayed clearance of the EPEC-like mouse pathogen Citrobacter rodentium and reversion to virulence of an nleB mutant. The activity of NleB suggests that EPEC and other attaching and effacing (A/E) pathogens antagonise death receptor induced apoptosis of infected cells, thereby blocking a major antimicrobial host response. PMID:24025841

  16. Activation of ERK signaling and induction of colon cancer cell death by piperlongumine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Piperlongumine (PPLGM) is a bioactive compound isolated from long peppers that shows selective toxicity towards a variety of cancer cell types including colon cancer. The signaling pathways that lead to cancer cell death in response to PPLGM exposure have not been previously identified. Our objectiv...

  17. Induction of Cancer Cell Death by Isoflavone: The Role of Multiple Signaling Pathways

    PubMed Central

    Li, Yiwei; Kong, Dejuan; Bao, Bin; Ahmad, Aamir; Sarkar, Fazlul H.

    2011-01-01

    Soy isoflavones have been documented as dietary nutrients broadly classified as “natural agents” which plays important roles in reducing the incidence of hormone-related cancers in Asian countries, and have shown inhibitory effects on cancer development and progression in vitro and in vivo, suggesting the cancer preventive or therapeutic activity of soy isoflavones against cancers. Emerging experimental evidence shows that isoflavones could induce cancer cell death by regulating multiple cellular signaling pathways including Akt, NF-κB, MAPK, Wnt, androgen receptor (AR), p53 and Notch signaling, all of which have been found to be deregulated in cancer cells. Therefore, homeostatic regulation of these important cellular signaling pathways by isoflavones could be useful for the activation of cell death signaling, which could result in the induction of apoptosis of both pre-cancerous and/or cancerous cells without affecting normal cells. In this article, we have attempted to summarize the current state-of-our-knowledge regarding the induction of cancer cell death pathways by isoflavones, which is believed to be mediated through the regulation of multiple cellular signaling pathways. The knowledge gained from this article will provide a comprehensive view on the molecular mechanism(s) by which soy isoflavones may exert their effects on the prevention of tumor progression and/or treatment of human malignancies, which would also aid in stimulating further in-depth mechanistic research and foster the initiation of novel clinical trials. PMID:22200028

  18. Redox Regulation of Intracellular Zinc: Molecular Signaling in the Life and Death of Neurons

    PubMed Central

    Aizenman, Elias

    2011-01-01

    Abstract Zn2+ has emerged as a major regulator of neuronal physiology, as well as an important signaling agent in neural injury. The intracellular concentration of this metal is tightly regulated through the actions of Zn2+ transporters and the thiol-rich metal binding protein metallothionein, closely linking the redox status of the cell to cellular availability of Zn2+. Accordingly, oxidative and nitrosative stress during ischemic injury leads to an accumulation of neuronal free Zn2+ and the activation of several downstream cell death processes. While this Zn2+ rise is an established signaling event in neuronal cell death, recent evidence suggests that a transient, sublethal accumulation of free Zn2+ can also play a critical role in neuroprotective pathways activated during ischemic preconditioning. Thus, redox-sensitive proteins, like metallothioneins, may play a critical role in determining neuronal cell fate by regulating the localization and concentration of intracellular free Zn2+. Antioxid. Redox Signal. 15, 2249–2263. PMID:20849376

  19. Ethylene signaling pathway and MAPK cascades are required for AAL toxin-induced programmed cell death.

    PubMed

    Mase, Keisuke; Mizuno, Takahito; Ishihama, Nobuaki; Fujii, Takayuki; Mori, Hitoshi; Kodama, Motoichiro; Yoshioka, Hirofumi

    2012-08-01

    Programmed cell death (PCD), known as hypersensitive response cell death, has an important role in plant defense response. The signaling pathway of PCD remains unknown. We employed AAL toxin and Nicotiana umbratica to analysis plant PCD. AAL toxin is a pathogenicity factor of the necrotrophic pathogen Alternaria alternata f. sp. lycopersici. N. umbratica is sensitive to AAL toxin, susceptible to pathogens, and effective in Tobacco rattle virus-based virus-induced gene silencing (VIGS). VIGS analyses indicated that AAL toxin-triggered cell death (ACD) is dependent upon the mitogen-activated protein (MAP) kinase kinase MEK2, which is upstream of both salicylic acid-induced protein kinase (SIPK) and wound-induced protein kinase (WIPK) responsible for ethylene (ET) synthesis. ET treatment of MEK2-silenced N. umbratica re-established ACD. In SIPK- and WIPK-silenced N. umbratica, ACD was compromised and ET accumulation was not observed. However, in contrast to the case of MEK2-silenced plants, ET treatment did not induce cell death in SIPK- and WIPK-silenced plants. This work showed that ET-dependent pathway and MAP kinase cascades are required in ACD. Our results suggested that MEK2-SIPK/WIPK cascades have roles in ET biosynthesis; however, SIPK and WIPK have other roles in ET signaling or another pathway leading to cell death by AAL toxin.

  20. Programmed cell death-10 enhances proliferation and protects malignant T cells from apoptosis.

    PubMed

    Lauenborg, Britt; Kopp, Katharina; Krejsgaard, Thorbjørn; Eriksen, Karsten W; Geisler, Carsten; Dabelsteen, Sally; Gniadecki, Robert; Zhang, Qian; Wasik, Mariusz A; Woetmann, Anders; Odum, Niels

    2010-10-01

    The programmed cell death-10 (PDCD10; also known as cerebral cavernous malformation-3 or CCM3) gene encodes an evolutionarily conserved protein associated with cell apoptosis. Mutations in PDCD10 result in cerebral cavernous malformations, an important cause of cerebral hemorrhage. PDCD10 is associated with serine/threonine kinases and phosphatases and modulates the extracellular signal-regulated kinase pathway suggesting a role in the regulation of cellular growth. Here we provide evidence of a constitutive expression of PDCD10 in malignant T cells and cell lines from peripheral blood of cutaneous T-cell lymphoma (Sezary syndrome) patients. PDCD10 is associated with protein phosphatase-2A, a regulator of mitogenesis and apoptosis in malignant T cells. Inhibition of oncogenic signal pathways [Jak3, Notch1, and nuclear factor-κB (NF-κB)] partly inhibits the constitutive PDCD10 expression, whereas an activator of Jak3 and NF-κB, interleukin-2 (IL-2), enhances PDCD10 expression. Functional data show that PDCD10 depletion by small interfering RNA induces apoptosis and decreases proliferation of the sensitive cells. To our knowledge, these data provide the first functional link between PDCD10 and cancer.

  1. Signalling mechanisms mediating Zn2+-induced TRPM2 channel activation and cell death in microglial cells

    PubMed Central

    Mortadza, Sharifah Syed; Sim, Joan A.; Stacey, Martin; Jiang, Lin-Hua

    2017-01-01

    Excessive Zn2+ causes brain damage via promoting ROS generation. Here we investigated the role of ROS-sensitive TRPM2 channel in H2O2/Zn2+-induced Ca2+ signalling and cell death in microglial cells. H2O2/Zn2+ induced concentration-dependent increases in cytosolic Ca2+ concentration ([Ca2+]c), which was inhibited by PJ34, a PARP inhibitor, and abolished by TRPM2 knockout (TRPM2-KO). Pathological concentrations of H2O2/Zn2+ induced substantial cell death that was inhibited by PJ34 and DPQ, PARP inhibitors, 2-APB, a TRPM2 channel inhibitor, and prevented by TRPM2-KO. Further analysis indicate that Zn2+ induced ROS production, PARP-1 stimulation, increase in the [Ca2+]c and cell death, all of which were suppressed by chelerythrine, a protein kinase C inhibitor, DPI, a NADPH-dependent oxidase (NOX) inhibitor, GKT137831, a NOX1/4 inhibitor, and Phox-I2, a NOX2 inhibitor. Furthermore, Zn2+-induced PARP-1 stimulation, increase in the [Ca2+]c and cell death were inhibited by PF431396, a Ca2+-sensitive PYK2 inhibitor, and U0126, a MEK/ERK inhibitor. Taken together, our study shows PKC/NOX-mediated ROS generation and PARP-1 activation as an important mechanism in Zn2+-induced TRPM2 channel activation and, TRPM2-mediated increase in the [Ca2+]c to trigger the PYK2/MEK/ERK signalling pathway as a positive feedback mechanism that amplifies the TRPM2 channel activation. Activation of these TRPM2-depenent signalling mechanisms ultimately drives Zn2+-induced Ca2+ overloading and cell death. PMID:28322340

  2. Cadmium and cellular signaling cascades: interactions between cell death and survival pathways.

    PubMed

    Thévenod, Frank; Lee, Wing-Kee

    2013-10-01

    Cellular stress elicited by the toxic metal Cd(2+) does not coerce the cell into committing to die from the onset. Rather, detoxification and adaptive processes are triggered concurrently, allowing survival until normal function is restored. With high Cd(2+), death pathways predominate. However, if sublethal stress levels affect cells for prolonged periods, as in chronic low Cd(2+) exposure, adaptive and survival mechanisms may deregulate, such that tumorigenesis ensues. Hence, death and malignancy are the two ends of a continuum of cellular responses to Cd(2+), determined by magnitude and duration of Cd(2+) stress. Signaling cascades are the key factors affecting cellular reactions to Cd(2+). This review critically surveys recent literature to outline major features of death and survival signaling pathways as well as their activation, interactions and cross talk in cells exposed to Cd(2+). Under physiological conditions, receptor activation generates 2nd messengers, which are short-lived and act specifically on effectors through their spatial and temporal dynamics to transiently alter effector activity. Cd(2+) recruits physiological 2nd messenger systems, in particular Ca(2+) and reactive oxygen species (ROS), which control key Ca(2+)- and redox-sensitive molecular switches dictating cell function and fate. Severe ROS/Ca(2+) signals activate cell death effectors (ceramides, ASK1-JNK/p38, calpains, caspases) and/or cause irreversible damage to vital organelles, such as mitochondria and endoplasmic reticulum (ER), whereas low localized ROS/Ca(2+) levels act as 2nd messengers promoting cellular adaptation and survival through signal transduction (ERK1/2, PI3K/Akt-PKB) and transcriptional regulators (Ref1-Nrf2, NF-κB, Wnt, AP-1, bestrophin-3). Other cellular proteins and processes targeted by ROS/Ca(2+) (metallothioneins, Bcl-2 proteins, ubiquitin-proteasome system, ER stress-associated unfolded protein response, autophagy, cell cycle) can evoke death or survival

  3. Signal Enhancement in AM-FM Interference

    DTIC Science & Technology

    1994-05-17

    the short-time linear assumption, it provides a good test of the suppression algorithm. A 10-ms Hamming window, a 4-ms frame, and a 2048-point DFT...complex suppression with a different test signal consisting of the AM-FM interference added to an information signal generated from a closing stapler...1st The results of an informal listening test are also listed in Table 1, based on the judgment of interference reduction and clarity of the information

  4. Colocalization of cell death with antigen deposition in skin enhances vaccine immunogenicity.

    PubMed

    Depelsenaire, Alexandra C I; Meliga, Stefano C; McNeilly, Celia L; Pearson, Frances E; Coffey, Jacob W; Haigh, Oscar L; Flaim, Christopher J; Frazer, Ian H; Kendall, Mark A F

    2014-09-01

    Vaccines delivered to the skin by microneedles-with and without adjuvants-have increased immunogenicity with lower doses than standard vaccine delivery techniques such as intramuscular or intradermal injection. However, the mechanisms underlying this skin-mediated "adjuvant" effect are not clear. Here, we show that the dynamic application of a microprojection array (the Nanopatch) to skin generates localized transient stresses invoking cell death around each projection. Nanopatch application caused significantly higher levels (∼65-fold) of cell death in murine ear skin than i.d. injection using a hypodermic needle. Measured skin cell death is associated with modeled stresses ∼1-10 MPa. Nanopatch-immunized groups also yielded consistently higher anti-immunoglobulin G endpoint titers (up to 50-fold higher) than i.d. groups after delivery of a split virion influenza vaccine. Importantly, colocalization of cell death with nearby live skin cells and delivered antigen was necessary for immunogenicity enhancement. These results suggest a correlation between cell death caused by the Nanopatch with increased immunogenicity. We propose that the localized cell death serves as a "physical immune enhancer" for the adjacent viable skin cells, which also receive antigen from the projections. This natural immune enhancer effect has the potential to mitigate or replace chemical-based adjuvants in vaccines.

  5. Role of TLR2- and TLR4-mediated signaling in Mycobacterium tuberculosis-induced macrophage death.

    PubMed

    Sánchez, Dulfary; Rojas, Mauricio; Hernández, Israel; Radzioch, Danuta; García, Luis F; Barrera, Luis F

    2010-01-01

    Infection of macrophages with Mycobacterium tuberculosis (Mtb) induces cell death by apoptosis or necrosis. TLRs 2 and 4 recognition of mycobacterial ligands has been independently associated to apoptosis induction. To try to understand the particular contribution of these receptors to apoptotic or necrotic signaling upon infection with live Mtb H37Rv, we used macrophage lines derived from wild-type or TLR2-, TLR4-, and MyD88-deficient mouse strains. Mtb-infection triggered apoptosis depending on a TLR2/TLR4/MyD88/p38/ERK/PI-3K/NF-kB pathway; however, necrosis was favored in absence of TLR4 signaling independently of p38, ERK1/2, PI-3K or NF-kappaB activity. In conclusion, our results indicate that cooperation between TLR2- and TLR4-dependent mediated signals play a critical role in macrophage apoptosis induced by Mtb and the TLR4-mediated signaling has important role in the maintenance of the balance between apoptotic vs. necrotic cell death induced by macrophage infection with Mtb.

  6. Inhibition of programmed cell death by cyclosporin A; preferential blocking of cell death induced by signals via TCR/CD3 complex and its mode of action.

    PubMed Central

    Yasutomi, D; Odaka, C; Saito, S; Niizeki, H; Kizaki, H; Tadakuma, T

    1992-01-01

    Cyclosporin A (CsA) is reported to inhibit programmed cell death. We confirmed this by using T-cell hybridomas which are inducible to programmed cell death by activation with immobilized anti-CD3 antibody or with anti-Thy 1.2 antibody. Cell death and DNA fragmentation, characteristic features of programmed cell death, were almost completely blocked by CsA or FK506. To investigate whether CsA inhibits only the cell death through the signals via the TCR/CD3 complex or all of the programmed cell death induced by various reagents, we further established CD4+8+ thymic lymphomas which result in programmed cell death after activation with calcium ionophore, dexamethasone, cyclic AMP or anti-CD3 antibody. It was revealed that CsA could block only the cell death mediated by the TCR/CD3 complex. For the clarification of the site of action of CsA, Ca2+ influx and endocytosis of receptors after stimulation with anti-CD3 antibody were monitored in the presence of CsA, and no significant effects of CsA were observed. Furthermore, prevention of cell death was examined by adding CsA at various periods of time after initiation of culture. CsA was found to exert its effect even when added after 4 h of cultivation, and the kinetic pattern of suppression was similar to that of the suppressive effect on IL-2 production. These observations indicate that in the events of programmed cell death, the major site of action of CsA will not be the inhibition of the immediate membrane events after activation of the TCR/CD3 complex but rather the interference in the function of molecules that transmit signals between membrane events and the activation of genes in the nucleus. Images Figure 2 Figure 3 PMID:1383138

  7. Cyclic programmed cell death stimulates hormone signaling and root development in Arabidopsis.

    PubMed

    Xuan, Wei; Band, Leah R; Kumpf, Robert P; Van Damme, Daniël; Parizot, Boris; De Rop, Gieljan; Opdenacker, Davy; Möller, Barbara K; Skorzinski, Noemi; Njo, Maria F; De Rybel, Bert; Audenaert, Dominique; Nowack, Moritz K; Vanneste, Steffen; Beeckman, Tom

    2016-01-22

    The plant root cap, surrounding the very tip of the growing root, perceives and transmits environmental signals to the inner root tissues. In Arabidopsis thaliana, auxin released by the root cap contributes to the regular spacing of lateral organs along the primary root axis. Here, we show that the periodicity of lateral organ induction is driven by recurrent programmed cell death at the most distal edge of the root cap. We suggest that synchronous bursts of cell death in lateral root cap cells release pulses of auxin to surrounding root tissues, establishing the pattern for lateral root formation. The dynamics of root cap turnover may therefore coordinate primary root growth with root branching in order to optimize the uptake of water and nutrients from the soil.

  8. Co-localization of cell death with antigen deposition in skin enhances vaccine immunogenicity

    PubMed Central

    Depelsenaire, Alexandra C.I.; Meliga, Stefano C.; McNeilly, Celia L.; Pearson, Frances E.; Coffey, Jacob W.; Haigh, Oscar L.; Flaim, Christopher J.; Frazer, Ian H.; Kendall, Mark A.F.

    2014-01-01

    Vaccines delivered to the skin by microneedles – with and without adjuvants – have increased immunogenicity with lower doses than standard vaccine delivery techniques such as intramuscular (i.m.) or intradermal (i.d.) injection. However, the mechanisms behind this skin-mediated ‘adjuvant’ effect are not clear. Here, we show that the dynamic application of a microprojection array (the Nanopatch) to skin generates localized transient stresses invoking cell death around each projection. Nanopatch application caused significantly higher levels (~65-fold) of cell death in murine ear skin than i.d. injection using a hypodermic needle. Measured skin cell death is associated with modeled stresses ~1–10 MPa. Nanopatch-immunized groups also yielded consistently higher anti-IgG endpoint titers (up to 50-fold higher) than i.d. groups after delivery of a split virion influenza vaccine. Importantly, co-localization of cell death with nearby live skin cells and delivered antigen was necessary for immunogenicity enhancement. These results suggest a correlation between cell death caused by the Nanopatch with increased immunogenicity. We propose that the localized cell death serves as a ‘physical immune enhancer’ for the adjacent viable skin cells, which also receive antigen from the projections. This natural immune enhancer effect has the potential to mitigate or replace chemical-based adjuvants in vaccines. PMID:24714201

  9. New nucleotide analogues with enhanced signal properties.

    PubMed

    Cherkasov, Dmitry; Biet, Thorsten; Bäuml, Englbert; Traut, Walther; Lohoff, Michael

    2010-01-01

    We describe synthesis and testing of a novel type of dye-modified nucleotides which we call macromolecular nucleotides (m-Nucs). Macromolecular nucleotides comprise a nucleotide moiety, a macromolecular linear linker, and a large macromolecular ligand carrying multiple fluorescent dyes. With incorporation of the nucleotide moiety into the growing nucleic acid strand during enzymatic synthesis, the macromolecular ligand together with the coupled dyes is bound to the nucleic acid. By the use of this new class of modified nucleotides, signals from multiple dye molecules can be obtained after a single enzymatic incorporation event. The modified nucleotides are considered especially useful in the fields of nanobiotechnology, where signal stability and intensity is a limiting factor.

  10. Programmed death-1/programmed death-L1 signaling pathway and its blockade in hepatitis C virus immunotherapy.

    PubMed

    Salem, Mohamed L; El-Badawy, Ahmed

    2015-10-18

    Chronic hepatitis C virus (HCV) infection is a public health issue that often progresses to life-threatening complications, including liver cirrhosis, fibrosis, and hepatocellular carcinoma. Impaired immune responses to HCV are key features of chronic HCV infection. Therefore, intervention strategies usually involve enhancing the immune responses against HCV. Cytotoxic CD8(+) T lymphocytes (CTLs) play a critical role in the control of HCV infection. However, their cytolytic function can be impaired by the expression of co-inhibitory molecules. Programmed death-1 (PD-1) receptor and its ligand PD-L1 function in a T cell co-inhibitory pathway, which either blocks the function of CTLs or the differentiation of CD8(+) T cells. During chronic HCV infection, the immune inhibitory receptor PD-1 is upregulated on dysfunctional HCV-specific CD8(+) T cells. As such, blockade of the PD-1/PD-L1 pathway in these CD8(+) T cells might restore their functional capabilities. Indeed, clinical trials using therapies to block this pathway have shown promise in the fostering of anti-HCV immunity. Understanding how chronic HCV infection induces upregulation of PD-1 on HCV specific T cells and how the PD-1/PD-L1 interaction develops HCV specific T cell dysfunction will accelerate the development of an efficacious prophylactic and therapeutic vaccination against chronic HCV infections, which will significantly improve HCV treatments and patient survival. In this review, we discuss the relationship between PD-1 expression and clinical responses and the potential use of PD-1 blockade for anti-HCV therapy.

  11. Blockade of programmed death-1/programmed death ligand pathway enhances the antitumor immunity of human invariant natural killer T cells.

    PubMed

    Kamata, Toshiko; Suzuki, Akane; Mise, Naoko; Ihara, Fumie; Takami, Mariko; Makita, Yuji; Horinaka, Atsushi; Harada, Kazuaki; Kunii, Naoki; Yoshida, Shigetoshi; Yoshino, Ichiro; Nakayama, Toshinori; Motohashi, Shinichiro

    2016-12-01

    The role of invariant natural killer T (iNKT) cells in antitumor immunity has been studied extensively, and clinical trials in patients with advanced cancer have revealed a prolonged survival in some cases. In recent years, humanized blocking antibodies against co-stimulatory molecules such as PD-1 have been developed. The enhancement of T cell function is reported to improve antitumor immunity, leading to positive clinical effects. However, there are limited data on the role of PD-1/programmed death ligand (PDL) molecules in human iNKT cells. In this study, we investigated the interaction between PD-1 on iNKT cells and PDL on antigen-presenting cells (APCs) in the context of iNKT cell stimulation. The blockade of PDL1 at the time of stimulation resulted in increased release of helper T cell (Th) 1 cytokines from iNKT cells, leading to the activation of NK cells. The direct antitumor function of iNKT cells was also enhanced after stimulation with anti-PDL1 antibody-treated APCs. According to these results, we conclude that the co-administration of anti-PDL1 antibody and alpha-galactosylceramide (αGalCer)-pulsed APCs enhances iNKT cell-mediated antitumor immunity.

  12. Liver protects metastatic prostate cancer from induced death by activating E-cadherin signaling.

    PubMed

    Ma, Bo; Wheeler, Sarah E; Clark, Amanda M; Whaley, Diana L; Yang, Min; Wells, Alan

    2016-11-01

    Liver is one of the most common sites of cancer metastasis. Once disseminated, the prognosis is poor as these tumors often display generalized chemoresistance, particularly for carcinomas that derive not from the aerodigestive tract. When these cancers seed the liver, the aggressive cells usually undergo a mesenchymal to epithelial reverting transition that both aids colonization and renders the tumor cells chemoresistant. In vitro studies demonstrate that hepatocytes drive this phenotypic shift. However, the in vivo evidence and the molecular signals that protect these cells from induced death are yet to be defined. Herein, we report that membrane surface E-cadherin-expressing prostate cancer cells were resistant to cell death by chemotherapeutic drugs but E-cadherin null cells or those expressing E-cadherin only in the cytoplasm were sensitive to death signals and chemotherapies both in vitro and in vivo. While cell-cell E-cadherin ligandation reduced mitogenesis, this chemoprotection was proliferation-independent as killing of both 5-ethynyl-2'-deoxyuridine-positive (or Ki67(+) ) and 5-ethynyl-2'-deoxyuridine-negative (Ki67(-) ) cells was inversely related to membrane-bound E-cadherin. Inhibiting the canonical survival kinases extracellular signal-regulated protein kinases, protein kinase B, and Janus kinase, which are activated by chemotherapeutics in epithelial cell-transitioned prostate cancer, abrogated the chemoresistance both in cell culture and in animal models of metastatic cancer. For disseminated tumors, protein kinase B disruption in itself had no effect on tumor survival but was synergistic with chemotherapy, leading to increased killing.

  13. Signal-enhancement reflective pulse oximeter with Fresnel lens

    NASA Astrophysics Data System (ADS)

    Chung, Shuang-Chao; Sun, Ching-Cherng

    2016-09-01

    In this paper, a new reflective pulse oximeter is proposed and demonstrated with implanting a Fresnel lens, which enhances the reflected signal. An optical simulation model incorporated with human skin characteristics is presented to evaluate the capability of the Fresnel lens. In addition, the distance between the light emitting diode and the photodiode is optimized. Compared with the other reflective oximeters, the reflected signal light detected by the photodiode is enhanced to more than 140%.

  14. Pepper pathogenesis-related protein 4c is a plasma membrane-localized cysteine protease inhibitor that is required for plant cell death and defense signaling.

    PubMed

    Kim, Nak Hyun; Hwang, Byung Kook

    2015-01-01

    Xanthomonas campestris pv. vesicatoria (Xcv) type III effector AvrBsT triggers programmed cell death (PCD) and activates the hypersensitive response (HR) in plants. Here, we isolated and identified the plasma membrane localized pathogenesis-related (PR) protein 4c gene (CaPR4c) from pepper (Capsicum annuum) leaves undergoing AvrBsT-triggered HR cell death. CaPR4c encodes a protein with a signal peptide and a Barwin domain. Recombinant CaPR4c protein expressed in Escherichia coli exhibited cysteine protease-inhibitor activity and ribonuclease (RNase) activity. Subcellular localization analyses revealed that CaPR4c localized to the plasma membrane in plant cells. CaPR4c expression was rapidly and specifically induced by avirulent Xcv (avrBsT) infection. Transient expression of CaPR4c caused HR cell death in pepper leaves, which was accompanied by enhanced accumulation of H2 O2 and significant induction of some defense-response genes. Deletion of the signal peptide from CaPR4c abolished the induction of HR cell death, indicating a requirement for plasma membrane localization of CaPR4c for HR cell death. CaPR4c silencing in pepper disrupted both basal and AvrBsT-triggered resistance responses, and enabled Xcv proliferation in infected leaves. H2 O2 accumulation, cell-death induction, and defense-response gene expression were distinctly reduced in CaPR4c-silenced pepper. CaPR4c overexpression in transgenic Arabidopsis plants conferred greater resistance against infection by Pseudomonas syringae pv. tomato and Hyaloperonospora arabidopsidis. These results collectively suggest that CaPR4c plays an important role in plant cell death and defense signaling.

  15. SFM signal parameter estimation based on an enhanced DSFMT algorithm

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Li, Xingguang; Chen, Dianren

    2017-01-01

    It is proposed a SFM signal parameter estimation method based on the Enhanced DSFMT(EDSFMT) algorithm and provided the derivation of transformation formulas in this paper .Analysis and simulations were performed, which proved its capability of arbitrary multi-component SFM signal parameter estimation.

  16. Tomographic Processing of Synthetic Aperture Radar Signals for Enhanced Resolution

    DTIC Science & Technology

    1989-11-01

    digital signal processing view of strip-mapping synthetic aperture radar," M.S. thesis , University of Illinois, Urbana, IL,1988." [571 David C. Munson...TOMOGRAPHIC PROCESSING OF 1 SYNTHETIC APERTURE I RADAR SIGNALS FOR ENHANCED RESOLUTION,I * Jerald Lee Bauck DTIC ELECTE JAN2419901D I I UNIVERSITY OF ILLINOIS...NC 27709-2211 ELEMENT NO. NO. NO CCESSION NO. 11i. TITLE (Include Security Classification) TOMOGRAPHIC PROCESSING OF SYNTHETIC APERTURE RADlAR SIGNALS

  17. Drug-induced death signaling strategy rapidly predicts cancer response to chemotherapy

    PubMed Central

    Montero, Joan; Sarosiek, Kristopher A.; DeAngelo, Joseph D.; Maertens, Ophélia; Ryan, Jeremy; Ercan, Dalia; Piao, Huiying; Horowitz, Neil S.; Berkowitz, Ross S.; Matulonis, Ursula; Jänne, Pasi A.; Amrein, Philip C.; Cichowski, Karen; Drapkin, Ronny; Letai, Anthony

    2015-01-01

    SUMMARY There is a lack of effective predictive biomarkers to precisely assign optimal therapy to cancer patients. While most efforts are directed at inferring drug response phenotype based on genotype, there is very focused and useful phenotypic information to be gained from directly perturbing the patient’s living cancer cell with the drug(s) in question. To satisfy this unmet need we developed the Dynamic BH3 Profiling technique to measure early changes in net pro-apoptotic signaling at the mitochondrion (‘priming’) induced by chemotherapeutic agents in cancer cells, not requiring prolonged ex vivo culture. We find in cell line and clinical experiments that early drug-induced death signaling measured by Dynamic BH3 Profiling predicts chemotherapy response across many cancer types and many agents, including combinations of chemotherapies. We propose that Dynamic BH3 Profiling can be used as a broadly applicable predictive biomarker to predict cytotoxic response of cancers to chemotherapeutics in vivo. PMID:25723171

  18. Controlling metabolism and cell death: at the heart of mitochondrial calcium signalling

    PubMed Central

    Murgia, Marta; Giorgi, Carlotta; Pinton, Paolo; Rizzuto, Rosario

    2009-01-01

    Transient increases in intracellular calcium concentration activate and coordinate a wide variety of cellular processes in virtually every cell type. This review describes the main homeostatic mechanisms that control Ca2+ transients, focusing on the mitochondrial checkpoint. We subsequently extend this paradigm to the cardiomyocyte and to the interplay between cytosol, endoplasmic reticulum and mitochondria that occurs beat-to-beat in excitation-contraction coupling. The mechanisms whereby mitochondria decode fast cytosolic calcium spikes are discussed in the light of the results obtained with recombinant photoproteins targeted to the mitochondrial matrix of contracting cardiomyocytes. Mitochondrial calcium homeostasis is then highlighted as a crucial point of convergence of the environmental signals that mediate cardiac cell death, both by necrosis and by apoptosis. Altogether we point to a role of the mitochondrion as an integrator of calcium signalling and fundamental decision maker in cardiomyocyte metabolism and survival. PMID:19285982

  19. Light acclimation, retrograde signalling, cell death and immune defences in plants.

    PubMed

    Karpiński, Stanisław; Szechyńska-Hebda, Magdalena; Wituszyńska, Weronika; Burdiak, Paweł

    2013-04-01

    This review confronts the classical view of plant immune defence and light acclimation with recently published data. Earlier findings have linked plant immune defences to nucleotide-binding site leucine-rich repeat (NBS-LRR)-dependent recognition of pathogen effectors and to the role of plasma membrane-localized NADPH-dependent oxidoreductase (AtRbohD), reactive oxygen species (ROS) and salicylic acid (SA). However, recent results suggest that plant immune defence also depends on the absorption of excessive light energy and photorespiration. Rapid changes in light intensity and quality often cause the absorption of energy, which is in excess of that required for photosynthesis. Such excessive light energy is considered to be a factor triggering photoinhibition and disturbance in ROS/hormonal homeostasis, which leads to cell death in foliar tissues. We highlight here the tight crosstalk between ROS- and SA-dependent pathways leading to light acclimation, and defence responses leading to pathogen resistance. We also show that LESION SIMULATING DISEASE 1 (LSD1) regulates and integrates these processes. Moreover, we discuss the role of plastid-nucleus signal transduction, photorespiration, photoelectrochemical signalling and 'light memory' in the regulation of acclimation and immune defence responses. All of these results suggest that plants have evolved a genetic system that simultaneously regulates systemic acquired resistance (SAR), cell death and systemic acquired acclimation (SAA).

  20. Systems modelling methodology for the analysis of apoptosis signal transduction and cell death decisions.

    PubMed

    Rehm, Markus; Prehn, Jochen H M

    2013-06-01

    Systems biology and systems medicine, i.e. the application of systems biology in a clinical context, is becoming of increasing importance in biology, drug discovery and health care. Systems biology incorporates knowledge and methods that are applied in mathematics, physics and engineering, but may not be part of classical training in biology. We here provide an introduction to basic concepts and methods relevant to the construction and application of systems models for apoptosis research. We present the key methods relevant to the representation of biochemical processes in signal transduction models, with a particular reference to apoptotic processes. We demonstrate how such models enable a quantitative and temporal analysis of changes in molecular entities in response to an apoptosis-inducing stimulus, and provide information on cell survival and cell death decisions. We introduce methods for analyzing the spatial propagation of cell death signals, and discuss the concepts of sensitivity analyses that enable a prediction of network responses to disturbances of single or multiple parameters.

  1. A cardiac mitochondrial cAMP signaling pathway regulates calcium accumulation, permeability transition and cell death

    PubMed Central

    Wang, Z; Liu, D; Varin, A; Nicolas, V; Courilleau, D; Mateo, P; Caubere, C; Rouet, P; Gomez, A-M; Vandecasteele, G; Fischmeister, R; Brenner, C

    2016-01-01

    Although cardiac cytosolic cyclic 3′,5′-adenosine monophosphate (cAMP) regulates multiple processes, such as beating, contractility, metabolism and apoptosis, little is known yet on the role of this second messenger within cardiac mitochondria. Using cellular and subcellular approaches, we demonstrate here the local expression of several actors of cAMP signaling within cardiac mitochondria, namely a truncated form of soluble AC (sACt) and the exchange protein directly activated by cAMP 1 (Epac1), and show a protective role for sACt against cell death, apoptosis as well as necrosis in primary cardiomyocytes. Upon stimulation with bicarbonate (HCO3−) and Ca2+, sACt produces cAMP, which in turn stimulates oxygen consumption, increases the mitochondrial membrane potential (ΔΨm) and ATP production. cAMP is rate limiting for matrix Ca2+ entry via Epac1 and the mitochondrial calcium uniporter and, as a consequence, prevents mitochondrial permeability transition (MPT). The mitochondrial cAMP effects involve neither protein kinase A, Epac2 nor the mitochondrial Na+/Ca2+ exchanger. In addition, in mitochondria isolated from failing rat hearts, stimulation of the mitochondrial cAMP pathway by HCO3− rescued the sensitization of mitochondria to Ca2+-induced MPT. Thus, our study identifies a link between mitochondrial cAMP, mitochondrial metabolism and cell death in the heart, which is independent of cytosolic cAMP signaling. Our results might have implications for therapeutic prevention of cell death in cardiac pathologies. PMID:27100892

  2. Inhibition of apoptosis signal-regulating kinase 1 enhances endochondral bone formation by increasing chondrocyte survival

    PubMed Central

    Eaton, G J; Zhang, Q-S; Diallo, C; Matsuzawa, A; Ichijo, H; Steinbeck, M J; Freeman, T A

    2014-01-01

    Endochondral ossification is the result of chondrocyte differentiation, hypertrophy, death and replacement by bone. The careful timing and progression of this process is important for normal skeletal bone growth and development, as well as fracture repair. Apoptosis Signal-Regulating Kinase 1 (ASK1) is a mitogen-activated protein kinase (MAPK), which is activated by reactive oxygen species and other cellular stress events. Activation of ASK1 initiates a signaling cascade known to regulate diverse cellular events including cytokine and growth factor signaling, cell cycle regulation, cellular differentiation, hypertrophy, survival and apoptosis. ASK1 is highly expressed in hypertrophic chondrocytes, but the role of ASK1 in skeletal tissues has not been investigated. Herein, we report that ASK1 knockout (KO) mice display alterations in normal growth plate morphology, which include a shorter proliferative zone and a lengthened hypertrophic zone. These changes in growth plate dynamics result in accelerated long bone mineralization and an increased formation of trabecular bone, which can be attributed to an increased resistance of terminally differentiated chondrocytes to undergo cell death. Interestingly, under normal cell culture conditions, mouse embryonic fibroblasts (MEFs) derived from ASK1 KO mice show no differences in either MAPK signaling or osteogenic or chondrogenic differentiation when compared with wild-type (WT) MEFs. However, when cultured with stress activators, H2O2 or staurosporine, the KO cells show enhanced survival, an associated decrease in the activation of proteins involved in death signaling pathways and a reduction in markers of terminal differentiation. Furthermore, in both WT mice treated with the ASK1 inhibitor, NQDI-1, and ASK1 KO mice endochondral bone formation was increased in an ectopic ossification model. These findings highlight a previously unrealized role for ASK1 in regulating endochondral bone formation. Inhibition of ASK1 has

  3. Enhanced release of primary signals may render intercellular signalling ineffective due to spatial aspects

    PubMed Central

    Kundrát, Pavel; Friedland, Werner

    2016-01-01

    Detailed mechanistic modelling has been performed of the intercellular signalling cascade between precancerous cells and their normal neighbours that leads to a selective removal of the precancerous cells by apoptosis. Two interconnected signalling pathways that were identified experimentally have been modelled, explicitly accounting for temporal and spatial effects. The model predicts highly non-linear behaviour of the signalling. Importantly, under certain conditions, enhanced release of primary signals by precancerous cells renders the signalling ineffective. This counter-intuitive behaviour arises due to spatial aspects of the underlying signalling scheme: Increased primary signalling by precancerous cells does, upon reaction with factors derived from normal cells, produce higher yields of apoptosis-triggering molecules. However, the apoptosis-triggering signals are formed farther from the precancerous cells, so that these are attacked less efficiently. Spatial effects thus may represent a novel analogue of negative feedback mechanisms. PMID:27645799

  4. Gamma oscillations of spiking neural populations enhance signal discrimination.

    PubMed

    Masuda, Naoki; Doiron, Brent

    2007-11-01

    Selective attention is an important filter for complex environments where distractions compete with signals. Attention increases both the gamma-band power of cortical local field potentials and the spike-field coherence within the receptive field of an attended object. However, the mechanisms by which gamma-band activity enhances, if at all, the encoding of input signals are not well understood. We propose that gamma oscillations induce binomial-like spike-count statistics across noisy neural populations. Using simplified models of spiking neurons, we show how the discrimination of static signals based on the population spike-count response is improved with gamma induced binomial statistics. These results give an important mechanistic link between the neural correlates of attention and the discrimination tasks where attention is known to enhance performance. Further, they show how a rhythmicity of spike responses can enhance coding schemes that are not temporally sensitive.

  5. Phenotypic Reversion or Death of Cancer Cells by Altering Signaling Pathways in Three-Dimensional Contexts

    PubMed Central

    Wang, Fei; Hansen, Rhonda K.; Radisky, Derek; Yoneda, Toshiyuki; Barcellos-Hoff, Mary Helen; Petersen, Ole W.; Turley, Eva A.; Bissell, Mina J.

    2010-01-01

    Background We previously used a three-dimensional (3D) reconstituted basement membrane (rBM) assay to demonstrate that tumorigenic HMT-3522 T4–2 human breast cells can be induced to form morphologically normal structures (“reversion”) by treatment with inhibitors of β1 integrin, the epidermal growth factor receptor (EGFR), or mitogen-activated protein kinase (MAPK). We have now used this assay to identify reversion and/or death requirements of several more aggressive human breast cancer cell lines. Methods Breast tumor cell lines MCF7, Hs578T, and MDA-MB-231 were cultured in 3D rBM and treated with inhibitors of β1 integrin, MAPK, or phosphatidylinositol 3-kinase (PI3K). MDA-MB-231 cells, which lack E-cadherin, were transfected with an E-cadherin cDNA. The extent of reversion was assessed by changes in morphology and polarity, growth in 3D rBM or soft agar, level of invasiveness, and tumor formation in nude mice. Results All three cell lines showed partial reversion (MCF7 the greatest and Hs578T the least) of tumorigenic properties treated with a single β1 integrin, MAPK, or PI3K inhibitor. Combined inhibition of β1 integrin and either PI3K or MAPK resulted in nearly complete phenotypic reversion (MDA-MB-231, MCF7) or in cell death (Hs578T). E-cadherin-transfected MDA-MB-231 cells showed partial reversion, but exposure of the transfectants to an inhibitor of β1 integrin, PI3K, or MAPK led to nearly complete reversion. Conclusion The 3D rBM assay can be used to identify signaling pathways that, when manipulated in concert, can lead to the restoration of morphologically normal breast structures or to death of the tumor cells, even highly metastatic cells. This approach may be useful to design therapeutic intervention strategies for aggressive breast cancers. PMID:12359858

  6. Mitochondria Death/Survival Signaling Pathways in Cardiotoxicity Induced by Anthracyclines and Anticancer-Targeted Therapies

    PubMed Central

    Montaigne, David; Hurt, Christopher; Neviere, Remi

    2012-01-01

    Anthracyclines remain the cornerstone of treatment in many malignancies but these agents have a cumulative dose relationship with cardiotoxicity. Development of cardiomyopathy and congestive heart failure induced by anthracyclines are typically dose-dependent, irreversible, and cumulative. Although past studies of cardiotoxicity have focused on anthracyclines, more recently interest has turned to anticancer drugs that target many proteins kinases, such as tyrosine kinases. An attractive model to explain the mechanism of this cardiotoxicity could be myocyte loss through cell death pathways. Inhibition of mitochondrial transition permeability is a valuable tool to prevent doxorubicin-induced cardiotoxicity. In response to anthracycline treatment, activation of several protein kinases, neuregulin/ErbB2 signaling, and transcriptional factors modify mitochondrial functions that determine cell death or survival through the modulation of mitochondrial membrane permeability. Cellular response to anthracyclines is also modulated by a myriad of transcriptional factors that influence cell fate. Several novel targeted chemotherapeutic agents have been associated with a small but worrying risk of left ventricular dysfunction. Agents such as trastuzumab and tyrosine kinase inhibitors can lead to cardiotoxicity that is fundamentally different from that caused by anthracyclines, whereas biological effects converge to the mitochondria as a critical target. PMID:22482055

  7. Blockade of constitutively activated ERK signaling enhances cytotoxicity of microtubule-destabilizing agents in tumor cells.

    PubMed

    Tanimura, Susumu; Uchiyama, Aya; Watanabe, Kazushi; Yasunaga, Masahiro; Inada, Yoshiyuki; Kawabata, Takumi; Iwashita, Ken-Ichi; Noda, Sinji; Ozaki, Kei-Ichi; Kohno, Michiaki

    2009-01-16

    The extracellular signal-regulated kinase (ERK) signaling pathway is constitutively activated in many human tumor cell types. Given the cytoprotective role of this pathway, we examined whether its specific blockade might sensitize human tumor cells to the induction of apoptosis by various anticancer drugs. Although blockade of ERK signaling alone did not induce substantial cell death, it resulted in marked and selective enhancement of the induction of apoptosis by microtubule-destabilizing agents in tumor cells in which the ERK pathway is constitutively activated. The synergistic activation of c-Jun NH(2)-terminal kinase by the combination of an ERK pathway inhibitor and a microtubule-destabilizing agent appeared to be responsible, at least in part, for this effect. These results suggest that administration of the combination of an ERK pathway inhibitor and a microtubule-destabilizing agent is a potential chemotherapeutic strategy for the treatment of tumor cells with constitutive activation of the ERK pathway.

  8. Live to die another way: modes of programmed cell death and the signals emanating from dying cells.

    PubMed

    Fuchs, Yaron; Steller, Hermann

    2015-06-01

    All life ends in death, but perhaps one of life's grander ironies is that it also depends on death. Cell-intrinsic suicide pathways, termed programmed cell death (PCD), are crucial for animal development, tissue homeostasis and pathogenesis. Originally, PCD was almost synonymous with apoptosis; recently, however, alternative mechanisms of PCD have been reported. Here, we provide an overview of several distinct PCD mechanisms, namely apoptosis, autophagy and necroptosis. In addition, we discuss the complex signals that emanate from dying cells, which can either trigger regeneration or instruct additional killing. Further advances in understanding the physiological roles of the various mechanisms of cell death and their associated signals will be important to selectively manipulate PCD for therapeutic purposes.

  9. Live to die another way: modes of programmed cell death and the signals emanating from dying cells

    PubMed Central

    Fuchs, Yaron; Steller, Hermann

    2015-01-01

    Preface All life ends in death, but perhaps one of life’s grander ironies is that it also depends on death. Cell-intrinsic suicide pathways, termed programmed cell death (PCD), are crucial for animal development, tissue homeostasis and pathogenesis. Originally, PCD was virtually synonymous with apoptosis, but recently, alternative PCD mechanisms have been reported. Here, we provide an overview of several distinct PCD mechanisms, namely apoptosis, autophagy and necroptosis. In addition, we discuss the complex signals emanating from dying cells, which can either fuel regeneration or instruct additional killing. Further advances in understanding the physiological role of multiple cell death mechanisms and associated signals will be important to selectively manipulate PCD for therapeutic purposes. PMID:25991373

  10. Method for enhancing signals transmitted over optical fibers

    DOEpatents

    Ogle, James W.; Lyons, Peter B.

    1983-01-01

    A method for spectral equalization of high frequency spectrally broadband signals transmitted through an optical fiber. The broadband signal input is first dispersed by a grating. Narrow spectral components are collected into an array of equalizing fibers. The fibers serve as optical delay lines compensating for material dispersion of each spectral component during transmission. The relative lengths of the individual equalizing fibers are selected to compensate for such prior dispersion. The output of the equalizing fibers couple the spectrally equalized light onto a suitable detector for subsequent electronic processing of the enhanced broadband signal.

  11. Method for enhancing signals transmitted over optical fibers

    DOEpatents

    Ogle, J.W.; Lyons, P.B.

    1981-02-11

    A method for spectral equalization of high frequency spectrally broadband signals transmitted through an optical fiber is disclosed. The broadband signal input is first dispersed by a grating. Narrow spectral components are collected into an array of equalizing fibers. The fibers serve as optical delay lines compensating for material dispersion of each spectral component during transmission. The relative lengths of the individual equalizing fibers are selected to compensate for such prior dispersion. The output of the equalizing fibers couple the spectrally equalized light onto a suitable detector for subsequent electronic processing of the enhanced broadband signal.

  12. Matrix Crosslinking Forces Tumor Progression by Enhancing Integrin signaling

    PubMed Central

    Levental, Kandice R.; Yu, Hongmei; Kass, Laura; Lakins, Johnathon N.; Egeblad, Mikala; Erler, Janine T.; Fong, Sheri F.T.; Csiszar, Katalin; Giaccia, Amato; Weninger, Wolfgang; Yamauchi, Mitsuo; Gasser, David L.; Weaver, Valerie M.

    2009-01-01

    Summary Tumors are characterized by extracellular matrix (ECM) remodeling and stiffening. The importance of ECM remodeling to cancer is appreciated; the relevance of stiffening is less clear. We found that breast tumorigenesis is accompanied by collagen crosslinking, ECM stiffening and increased focal adhesions. Inducing collagen crosslinking stiffened the ECM, promoted focal adhesions, enhanced PI3 Kinase (PI3K) activity, and induced the invasion of an oncogene-initiated epithelium. Inhibiting integrin signaling repressed the invasion of a premalignant epithelium into a stiffened, crosslinked ECM, and forced integrin clustering promoted focal adhesions, enhanced PI3K signaling and induced the invasion of a premalignant epithelium. Consistently, reducing lysyl oxidase-mediated collagen crosslinking prevented MMTV-Neu-induced fibrosis, decreased focal adhesions and PI3K activity, impeded malignancy and lowered tumor incidence. These data show how collagen crosslinking can modulate tissue fibrosis and stiffness to force focal adhesions, growth factor signaling and breast malignancy. PMID:19931152

  13. Vitamin D receptor signaling enhances locomotive ability in mice.

    PubMed

    Sakai, Sadaoki; Suzuki, Miho; Tashiro, Yoshihito; Tanaka, Keisuke; Takeda, Satoshi; Aizawa, Ken; Hirata, Michinori; Yogo, Kenji; Endo, Koichi

    2015-01-01

    Bone fractures markedly reduce quality of life and life expectancy in elderly people. Although osteoporosis increases bone fragility, fractures frequently occur in patients with normal bone mineral density. Because most fractures occur on falling, preventing falls is another focus for reducing bone fractures. In this study, we investigated the role of vitamin D receptor (VDR) signaling in locomotive ability. In the rotarod test, physical exercise enhanced locomotive ability of wild-type (WT) mice by 1.6-fold, whereas exercise did not enhance locomotive ability of VDR knockout (KO) mice. Compared with WT mice, VDR KO mice had smaller peripheral nerve axonal diameter and disordered AChR morphology on the extensor digitorum longus muscle. Eldecalcitol (ED-71, ELD), an analog of 1,25(OH)2 D3 , administered to rotarod-trained C57BL/6 mice enhanced locomotor performance compared with vehicle-treated nontrained mice. The area of AChR cluster on the extensor digitorum longus was greater in ELD-treated mice than in vehicle-treated mice. ELD and 1,25(OH)2 D3 enhanced expression of IGF-1, myelin basic protein, and VDR in rat primary Schwann cells. VDR signaling regulates neuromuscular maintenance and enhances locomotive ability after physical exercise. Further investigation is required, but Schwann cells and the neuromuscular junction are targets of vitamin D3 signaling in locomotive ability.

  14. Signaling pathways that regulate life and cell death: evolution of apoptosis in the context of self-defense.

    PubMed

    Muñoz-Pinedo, Cristina

    2012-01-01

    Programmed Cell Death is essential for the life cycle of many organisms. Cell death in multicellular organisms can occur as a consequence of massive damage (necrosis) or in a controlled form, through engagement of diverse biochemical programs. The best well known form of programmed cell death is apoptosis. Apoptosis occurs in animals as a consequence of a variety of stimuli including stress and social signals and it plays essential roles in morphogenesis and immune defense. The machinery of apoptosis is well conserved among animals and it is composed of caspases (the proteases which execute cell death), adapter proteins (caspase activators), Bcl-2 family proteins and Inhibitor of Apoptosis Proteins (IAPs). We will describe in this chapter the main apoptotic pathways in animals: the extrinsic (death receptor-mediated), the intrinsic/mitochondrial and the Granzyme B pathway. Other forms of non-apoptotic Programmed Cell Death which occur in animals will also be discussed. We will summarize the current knowledge about apoptotic-like and other forms of cell death in other organisms such as plants and protists.Additionally, we will discuss the hypothesis that apoptosis originated as part of a host defense mechanism. We will explore the similarities between the protein complexes which mediate apoptosis (apoptosomes) and complexes involved in immunity: inflammasomes. Additional functions of apoptotic proteins related to immune function will be summarized, in an effort to explore the evolutionary origins of cell death.

  15. Enhancement of endocannabinoid signaling protects against cocaine-induced neurotoxicity

    SciTech Connect

    Vilela, Luciano R.; Gobira, Pedro H.; Viana, Thercia G.; Medeiros, Daniel C.; Ferreira-Vieira, Talita H.; Doria, Juliana G.; Rodrigues, Flávia; Aguiar, Daniele C.; Pereira, Grace S.; Massessini, André R.; Ribeiro, Fabíola M.; Oliveira, Antonio Carlos P. de; Moraes, Marcio F.D.; Moreira, Fabricio A.

    2015-08-01

    Cocaine is an addictive substance with a potential to cause deleterious effects in the brain. The strategies for treating its neurotoxicity, however, are limited. Evidence suggests that the endocannabinoid system exerts neuroprotective functions against various stimuli. Thus, we hypothesized that inhibition of fatty acid amide hydrolase (FAAH), the main enzyme responsible for terminating the actions of the endocannabinoid anandamide, reduces seizures and cell death in the hippocampus in a model of cocaine intoxication. Male Swiss mice received injections of endocannabinoid-related compounds followed by the lowest dose of cocaine that induces seizures, electroencephalographic activity and cell death in the hippocampus. The molecular mechanisms were studied in primary cell culture of this structure. The FAAH inhibitor, URB597, reduced cocaine-induced seizures and epileptiform electroencephalographic activity. The cannabinoid CB{sub 1} receptor selective agonist, ACEA, mimicked these effects, whereas the antagonist, AM251, prevented them. URB597 also inhibited cocaine-induced activation and death of hippocampal neurons, both in animals and in primary cell culture. Finally, we investigated if the PI3K/Akt/ERK intracellular pathway, a cell surviving mechanism coupled to CB{sub 1} receptor, mediated these neuroprotective effects. Accordingly, URB597 injection increased ERK and Akt phosphorylation in the hippocampus. Moreover, the neuroprotective effect of this compound was reversed by the PI3K inhibitor, LY294002. In conclusion, the pharmacological facilitation of the anandamide/CB1/PI3K signaling protects the brain against cocaine intoxication in experimental models. This strategy may be further explored in the development of treatments for drug-induced neurotoxicity. - Highlights: • Cocaine toxicity is characterized by seizures and hippocampal cell death. • The endocannabinoid anandamide acts as a brain protective mechanism. • Inhibition of anandamide hydrolysis

  16. Expression of FADD and cFLIPL balances mitochondrial integrity and redox signaling to substantiate apoptotic cell death.

    PubMed

    Ranjan, Kishu; Pathak, Chandramani

    2016-11-01

    FADD and cFLIP both are pivotal components of death receptor signaling. The cellular signaling of apoptosis accomplished with death receptors and mitochondria follows independent pathways for cell death. FADD and cFLIP both have an important role in the regulation of apoptotic and non-apoptotic functions. Dysregulated expression of FADD and cFLIP is associated with resistance to apoptosis in cancer cells. Mitochondria are known to play critical role in maintaining cellular respiration and homeostasis in the cells as well as transduces various signals to determine the fate of cell death. However, involvement of FADD and cFLIP in regulation of mitochondrial integrity and programmed cell death signaling to define the fate of cells remains elusive. In the present study, we explored that, induced expression of FADD challenges the mitochondrial integrity and pulverizes the membrane potential by altering the expression of Bcl-2 and cytochrome c. In contrast, mutant of FADD was unable to affect the mitochondrial integrity. Interestingly, expression of FADD and cFLIP helps to balance redox potential by regulating the anti-oxidant levels. Further, we noticed that, knockdown of cFLIPL and induced expression of FADD rapidly accumulate intracellular ROS accompanied by JNK1 activation to substantiate apoptosis. Notably, the ectopic expression of cFLIPL resists the sensitivity of cancer cells against apoptosis inducers Etoposide and HA14-1. Altogether, our findings suggest that FADD and cFLIPL are important modulators of mitochondrial-associated apoptosis apart from the death receptor signaling.

  17. Blockade of interleukin-6 signalling with siltuximab enhances melphalan cytotoxicity in preclinical models of multiple myeloma.

    PubMed

    Hunsucker, Sally A; Magarotto, Valeria; Kuhn, Deborah J; Kornblau, Steven M; Wang, Michael; Weber, Donna M; Thomas, Sheeba K; Shah, Jatin J; Voorhees, Peter M; Xie, Hong; Cornfeld, Mark; Nemeth, Jeffrey A; Orlowski, Robert Z

    2011-03-01

    Signalling through the interleukin (IL)-6 pathway induces proliferation and drug resistance of multiple myeloma cells. We therefore sought to determine whether the IL-6-neutralizing monoclonal antibody siltuximab, formerly CNTO 328, could enhance the activity of melphalan, and to examine some of the mechanisms underlying this interaction. Siltuximab increased the cytotoxicity of melphalan in KAS-6/1, INA-6, ANBL-6, and RPMI 8226 human myeloma cell lines (HMCLs) in an additive-to-synergistic manner, and sensitized resistant RPMI 8226.LR5 cells to melphalan. These anti-proliferative effects were accompanied by enhanced activation of drug-specific apoptosis in HMCLs grown in suspension, and in HMCLs co-cultured with a human-derived stromal cell line. Siltuximab with melphalan enhanced activation of caspase-8, caspase-9, and the downstream effector caspase-3 compared with either of the single agents. This increased induction of cell death occurred in association with enhanced Bak activation. Neutralization of IL-6 also suppressed signalling through the phosphoinositide 3-kinase/Akt pathway, as evidenced by decreased phosphorylation of Akt, p70 S6 kinase and 4E-BP1. Importantly, the siltuximab/melphalan regimen demonstrated enhanced anti-proliferative effects against primary plasma cells derived from patients with myeloma, monoclonal gammopathy of undetermined significance, and amyloidosis. These studies provide a rationale for translation of siltuximab into the clinic in combination with melphalan-based therapies.

  18. Zinc induces cell death in immortalized embryonic hippocampal cells via activation of Akt-GSK-3beta signaling.

    PubMed

    Min, Young Kyu; Lee, Jong Eun; Chung, Kwang Chul

    2007-01-15

    Zinc is an essential catalytic and structural element of many proteins and a signaling messenger that is released by neuronal activity at many central excitatory synapses. Excessive synaptic release of zinc followed by entry into vulnerable neurons contributes severe neuronal cell death. We have previously observed that zinc-induced neuronal cell death is accompanied by Akt activation in embryonic hippocampal progenitor (H19-7) cells. In the present study, we examined the role of Akt activation and its downstream signaling events during extracellular zinc-induced neuronal cell death. Treatment of H19-7 cells with 10 microM of zinc plus zinc ionophore, pyrithione, led to increased phosphorylation of Akt at Ser-473/Thr-308 and increased Akt kinase activity. Zinc-induced Akt activation was accompanied by increased Tyr-phosphorylated GSK-3beta as well as increased GSK-3beta kinase activity. Transient overexpression of a kinase-deficient Akt mutant remarkably suppressed GSK-3beta activation and cell death. Furthermore, tau phosphorylation, but not the degradation of beta-catenin, was dependent upon zinc-induced GSK-3beta activation and contributed to cell death. The current data suggest that, following exposure to zinc, the sequential activation of Akt and GSK-3beta plays an important role directing hippocampal neural precursor cell death.

  19. Effects of mass density enhancements on VLF transmitter signals

    NASA Astrophysics Data System (ADS)

    Boudjada, Mohammed Y.; Lammer, Helmut; Al-Haddad, Eimad; Leitzinger, Martin; Krauss, Sandro

    2015-04-01

    We study the variation of the electric field measurements recorded by DEMETER micro-satellite above specific very low frequency (VLF) transmitters. The investigated period starts from August 2004 to December 2010. The VLF signals are combined with the mass density measurements recorded, in the same time interval, by GRACE and CHAMP satellites. Particular enhancements of the mass densities were observed at polar and sub-polar regions by both satellites. Those mass density enhancements are found to propagate from the northern or southern hemisphere to the equator region. We attempt in this study to analyse the VLF signal variations in the time interval where the mass density enhancements are recorded. Such disturbances of the atmosphere can probably affect the Earth's ionosphere. The VLF signal may be attenuated and then not detected by DEMETER. We find that it is the case at some specific occasions. Nevertheless we show that several parameters have to be taken into consideration: (a) the origin of the mass density enhancement in the polar region (e.g. solar particles), (b) its phase speed from the pole to the equator and (c) the satellite (CHAMP, DEMETER, GRACE) local time.

  20. Pre-B-cell colony-enhancing factor protects against apoptotic neuronal death and mitochondrial damage in ischemia

    PubMed Central

    Wang, Xiaowan; Li, Hailong; Ding, Shinghua

    2016-01-01

    We previously demonstrated that Pre-B-cell colony-enhancing factor (PBEF), also known as nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in mammalian NAD+ biosynthesis pathway, plays a brain and neuronal protective role in ischemic stroke. In this study, we further investigated the mechanism of its neuroprotective effect after ischemia in the primary cultured mouse cortical neurons. Using apoptotic cell death assay, fluorescent imaging, molecular biology, mitochondrial biogenesis measurements and Western blotting analysis, our results show that the overexpression of PBEF in neurons can significantly promote neuronal survival, reduce the translocation of apoptosis inducing factor (AIF) from mitochondria to nuclei and inhibit the activation of capase-3 after glutamate-induced excitotoxicity. We further found that the overexpression of PBEF can suppress glutamate-induced mitochondrial fragmentation, the loss of mitochondrial DNA (mtDNA) content and the reduction of PGC-1 and NRF-1 expressions. Furthermore, these beneficial effects by PBEF are dependent on its enzymatic activity of NAD+ synthesis. In summary, our study demonstrated that PBEF ameliorates ischemia-induced neuronal death through inhibiting caspase-dependent and independent apoptotic signaling pathways and suppressing mitochondrial damage and dysfunction. Our study provides novel insights into the mechanisms underlying the neuroprotective effect of PBEF, and helps to identify potential targets for ischemic stroke therapy. PMID:27576732

  1. Cypermethrin Induces Macrophages Death through Cell Cycle Arrest and Oxidative Stress-Mediated JNK/ERK Signaling Regulated Apoptosis

    PubMed Central

    Huang, Fang; Liu, Qiaoyun; Xie, Shujun; Xu, Jian; Huang, Bo; Wu, Yihua; Xia, Dajing

    2016-01-01

    Cypermethrin is one of the most highly effective synthetic pyrethroid insecticides. The toxicity of cypermethrin to the reproductive and nervous systems has been well studied. However, little is known about the toxic effect of cypermethrin on immune cells such as macrophages. Here, we investigated the cytotoxicity of cypermethrin on macrophages and the underlying molecular mechanisms. We found that cypermethrin reduced cell viability and induced apoptosis in RAW 264.7 cells. Cypermethrin also increased reactive oxygen species (ROS) production and DNA damage in a dose-dependent manner. Moreover, cypermethrin-induced G1 cell cycle arrest was associated with an enhanced expression of p21, wild-type p53, and down-regulation of cyclin D1, cyclin E and CDK4. In addition, cypermethrin treatment activated MAPK signal pathways by inducing c-Jun N-terminal kinase (JNK) and extracellular regulated protein kinases 1/2 ERK1/2 phosphorylation, and increased the cleaved poly ADP-ribose polymerase (PARP). Further, pretreatment with antioxidant N-acetylcysteine (NAC) effectively abrogated cypermethrin-induced cell cytotoxicity, G1 cell cycle arrest, DNA damage, PARP activity, and JNK and ERK1/2 activation. The specific JNK inhibitor (SP600125) and ERK1/2 inhibitor (PD98059) effectively reversed the phosphorylation level of JNK and ERK1/2, and attenuated the apoptosis. Taken together, these data suggested that cypermethrin caused immune cell death via inducing cell cycle arrest and apoptosis regulated by ROS-mediated JNK/ERK pathway. PMID:27322250

  2. Death receptor-associated pro-apoptotic signaling in aged skeletal muscle.

    PubMed

    Pistilli, Emidio E; Jackson, Janna R; Alway, Stephen E

    2006-12-01

    Tumor necrosis factor-alpha (TNF-alpha) is elevated in the serum as a result of aging and it promotes pro-apoptotic signaling upon binding to the type I TNF receptor. It is not known if activation of this apoptotic pathway contributes to the well-documented age-associated decline in muscle mass (i.e. sarcopenia). We tested the hypothesis that skeletal muscles from aged rodents would exhibit elevations in markers involved in the extrinsic apoptotic pathway when compared to muscles from young adult rodents, thereby contributing to an increased incidence of nuclear apoptosis in these muscles. The plantaris (fast) and soleus (slow) muscles were studied in young adult (5-7 mo, n=8) and aged (33 mo, n=8) Fischer(344) x Brown Norway rats. Muscles from aged rats were significantly smaller while exhibiting a greater incidence of apoptosis. Furthermore, muscles from aged rats had higher type I TNF receptor and Fas associated death domain protein (FADD) mRNA, protein contents for FADD, BCL-2 Interacting Domain (Bid), FLICE-inhibitory protein (FLIP), and enzymatic activities of caspase-8 and caspase-3 than muscles from young adult rats. Significant correlations were observed in the plantaris muscle between caspase activity and muscle weight and the apoptotic index, while similar relationships were not found in the soleus. These data demonstrate that pro-apoptotic signaling downstream of the TNF receptor is active in aged muscles. Furthermore, our data extend the previous demonstration that type II fibers are preferentially affected by aging and support the hypothesis that type II fiber containing skeletal muscles may be more susceptible to muscle mass loses via the extrinsic apoptotic pathway.

  3. Redox Signaling in Diabetic Nephropathy: Hypertrophy versus Death Choices in Mesangial Cells and Podocytes.

    PubMed

    Manda, Gina; Checherita, Alexandru-Ionel; Comanescu, Maria Victoria; Hinescu, Mihail Eugen

    2015-01-01

    This review emphasizes the role of oxidative stress in diabetic nephropathy, acting as trigger, modulator, and linker within the complex network of pathologic events. It highlights key molecular pathways and new hypothesis in diabetic nephropathy, related to the interferences of metabolic, oxidative, and inflammatory stresses. Main topics this review is addressing are biomarkers of oxidative stress in diabetic nephropathy, the sources of reactive oxygen species (mitochondria, NADPH-oxidases, hyperglycemia, and inflammation), and the redox-sensitive signaling networks (protein kinases, transcription factors, and epigenetic regulators). Molecular switches deciding on the renal cells fate in diabetic nephropathy are presented, such as hypertrophy versus death choices in mesangial cells and podocytes. Finally, the antioxidant response of renal cells in diabetic nephropathy is tackled, with emphasis on targeted therapy. An integrative approach is needed for identifying key molecular networks which control cellular responses triggered by the array of stressors in diabetic nephropathy. This will foster the discovery of reliable biomarkers for early diagnosis and prognosis, and will guide the discovery of new therapeutic approaches for personalized medicine in diabetic nephropathy.

  4. Mitochondrial calcium signalling and cell death: approaches for assessing the role of mitochondrial Ca2+ uptake in apoptosis

    PubMed Central

    Hajnóczky, György; Csordás, György; Das, Sudipto; Garcia-Perez, Cecilia; Saotome, Masao; Roy, Soumya Sinha; Yi, Muqing

    2009-01-01

    Summary Local Ca2+ transfer between adjoining domains of the sarcoendoplasmic reticulum (ER/SR) and mitochondria allows ER/SR Ca2+ release to activate mitochondrial Ca2+ uptake and to evoke a matrix [Ca2+] ([Ca2+]m) rise. [Ca2+]m exerts control on several steps of energy metabolism to synchronize ATP generation with cell function. However, calcium signal propagation to the mitochondria may also ignite a cell death program through opening of the permeability transition pore (PTP). This occurs when the Ca2+ release from the ER/SR is enhanced or is coincident with sensitization of the PTP. Recent studies have shown that several pro-apoptotic factors, including members of the Bcl-2 family proteins and reactive oxygen species (ROS) regulate the Ca2+ sensitivity of both the Ca2+ release channels in the ER and the PTP in the mitochondria. To test the relevance of the mitochondrial Ca2+ accumulation in various apoptotic paradigms, methods are available for buffering of [Ca2+], for dissipation of the driving force of the mitochondrial Ca2+ uptake and for inhibition of the mitochondrial Ca2+ transport mechanisms. However, in intact cells, the efficacy and the specificity of these approaches have to be established. Here we discuss mechanisms that recruit the mitochondrial calcium signal to a pro-apoptotic cascade and the approaches available for assessment of the relevance of the mitochondrial Ca2+ handling in apoptosis. We also present a systematic evaluation of the effect of ruthenium red and Ru360, two inhibitors of mitochondrial Ca2+ uptake on cytosolic [Ca2+] and [Ca2+]m in intact cultured cells. PMID:17074387

  5. Observations of enhanced OTR signals from a compressed electron beam

    SciTech Connect

    Lumpkin, A.H.; Sereno, N.S.; Borland, M.; Li, Y.; Nemeth, K.; Pasky, S.; /Argonne

    2008-05-01

    The Advanced Photon Source (APS) injector complex includes an option for photocathode (PC) gun beam injection into the 450-MeV S-band linac. At the 150-MeV point, a 4-dipole chicane was used to compress the micropulse bunch length from a few ps to sub 0.5 ps (FWHM). Noticeable enhancements of the optical transition radiation (OTR) signal sampled after the APS chicane were then observed as has been reported in LCLS injector commissioning. A FIR CTR detector and interferometer were used to monitor the bunch compression process and correlate the appearance of localized spikes of OTR signal (5 to 10 times brighter than adjacent areas) within the beam image footprint. We have done spectral dependency measurements at 375 MeV with a series of band pass filters centered in 50-nm increments from 400 to 700 nm and observed a broadband enhancement in these spikes. Discussions of the possible mechanisms will be presented.

  6. Enhanced Multistatic Active Sonar via Innovative Signal Processing

    DTIC Science & Technology

    2015-09-30

    Grove, CA, November, 2014. [in press, refereed]. C . Gianelli, L. Xu, and J. Li, " Active Sonar Systems in the Presence of Strong Direct Blast", Oceans...3. DATES COVERED (From - To) Oct. 01, 2014-Sept. 30, 2015 4. TITLE AND SUBTITLE Enhanced Multistatic Active Sonar via Innovative Signal... active sonar (CAS) in the presence of strong direct blast is studied for the Doppler-tolerant linear frequency modulation waveform. A receiver design

  7. Enhanced Multistatic Active Sonar via Innovative Signal Processing

    DTIC Science & Technology

    2014-09-30

    DATES COVERED (From - To) Oct. 01. 2013-Sept. 30, 2014 4. TITLE AND SUBTITLE Enhanced Multistatic Active Sonar via Innovative Signal Processing 5a...DISTRIBUTION AVAILABILITY STATEMENT Approved for Public Release; Distribution is Unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Pulsed active sonar ...PAS) and continuous active sonar (CAS) in the presence of strong direct blast are studied for the Doppler-tolerant linear frequency modulation

  8. Ergosterol peroxide activates Foxo3-mediated cell death signaling by inhibiting AKT and c-Myc in human hepatocellular carcinoma cells

    PubMed Central

    Hu, Liming; Du, William W.; Jiao, Chunwei; Pan, Honghui; Sdiri, Mouna; Wu, Nan; Xie, Yizhen; Yang, Burton B.

    2016-01-01

    Sterols are the important active ingredients of fungal secondary metabolites to induce death of tumor cells. In our previous study, we found that ergosterol peroxide (5α, 8α-epidioxiergosta-6, 22-dien-3β-ol), purified from Ganoderma lucidum, induced human cancer cell death. Since the amount of purified ergosterol peroxide is not sufficient to perform in vivo experiments or apply clinically, we developed an approach to synthesize ergosterol peroxide chemically. After confirming the production of ergosterol peroxide, we examined the biological functions of the synthetic ergosterol peroxide. The results showed that ergosterol peroxide induced cell death and inhibited cell migration, cell cycle progression, and colony growth of human hepatocellular carcinoma cells. We further examined the mechanism associated with this effect and found that treatment with ergosterol peroxide increased the expression of Foxo3 mRNA and protein in HepG2 cells. The upstream signal proteins pAKT and c-Myc, which can inhibit Foxo3 functions, were clearly decreased in HepG2 cells treated with ergosterol peroxide. The levels of Puma and Bax, pro-apoptotic proteins, were effectively enhanced. Our results suggest that ergosterol peroxide stimulated Foxo3 activity by inhibiting pAKT and c-Myc and activating pro-apoptotic protein Puma and Bax to induce cancer cell death. PMID:27058618

  9. Enhancement of endocannabinoid signaling protects against cocaine-induced neurotoxicity.

    PubMed

    Vilela, Luciano R; Gobira, Pedro H; Viana, Thercia G; Medeiros, Daniel C; Ferreira-Vieira, Talita H; Doria, Juliana G; Rodrigues, Flávia; Aguiar, Daniele C; Pereira, Grace S; Massessini, André R; Ribeiro, Fabíola M; de Oliveira, Antonio Carlos P; Moraes, Marcio F D; Moreira, Fabricio A

    2015-08-01

    Cocaine is an addictive substance with a potential to cause deleterious effects in the brain. The strategies for treating its neurotoxicity, however, are limited. Evidence suggests that the endocannabinoid system exerts neuroprotective functions against various stimuli. Thus, we hypothesized that inhibition of fatty acid amide hydrolase (FAAH), the main enzyme responsible for terminating the actions of the endocannabinoid anandamide, reduces seizures and cell death in the hippocampus in a model of cocaine intoxication. Male Swiss mice received injections of endocannabinoid-related compounds followed by the lowest dose of cocaine that induces seizures, electroencephalographic activity and cell death in the hippocampus. The molecular mechanisms were studied in primary cell culture of this structure. The FAAH inhibitor, URB597, reduced cocaine-induced seizures and epileptiform electroencephalographic activity. The cannabinoid CB1 receptor selective agonist, ACEA, mimicked these effects, whereas the antagonist, AM251, prevented them. URB597 also inhibited cocaine-induced activation and death of hippocampal neurons, both in animals and in primary cell culture. Finally, we investigated if the PI3K/Akt/ERK intracellular pathway, a cell surviving mechanism coupled to CB1 receptor, mediated these neuroprotective effects. Accordingly, URB597 injection increased ERK and Akt phosphorylation in the hippocampus. Moreover, the neuroprotective effect of this compound was reversed by the PI3K inhibitor, LY294002. In conclusion, the pharmacological facilitation of the anandamide/CB1/PI3K signaling protects the brain against cocaine intoxication in experimental models. This strategy may be further explored in the development of treatments for drug-induced neurotoxicity.

  10. Gold nanorods as photothermal agents and autofluorescence enhancer to track cell death during plasmonic photothermal therapy

    NASA Astrophysics Data System (ADS)

    Kannadorai, Ravi Kumar; Chiew, Geraldine Giap Ying; Luo, Kathy Qian; Liu, Quan

    2015-07-01

    The transverse and longitudinal plasmon resonance in gold nanorods can be exploited to localize the photothermal therapy and influence the fluorescence to monitor the treatment outcome at the same time. While the longitudinal plasmon peak contributes to the photothermal effect, the transverse peak can enhance fluorescence. After cells take in PEGylated nanorods through endocytosis, autofluorescence from endogenous fluorophores such as nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) in the mitochondria is enhanced two times, which is a good indicator of the respiratory status of the cell. When cells are illuminated continuously with near infrared laser, the temperature reaches the hyperthermic region within the first four minutes, which demonstrates the efficiency of gold nanorods in photothermal therapy. The cell viability test and autofluorescence intensity show good correlation indicating the progress of cell death over time.

  11. Mechanical noise enhances signal transmission in the bullfrog sacculus.

    PubMed

    Indresano, Andrew A; Frank, Jonathan E; Middleton, Pameia; Jaramillo, Fernán

    2003-09-01

    Noise has been commonly thought to degrade the performance of sensory systems. However, it is now clear that the detection and transmission of weak signals in sensory systems can be enhanced by noise via stochastic resonance (SR). In hair cells, the quality of mechanoelectrical transduction is enhanced up to twofold by nanometer level mechanical noise acting on the hair bundle. We wanted to know whether these gains could be preserved, perhaps even enhanced, as information flows across hair cell synapses, and into the stream of action potentials that in the frog conveys acoustic information to the central nervous system. To approach this question, we studied the effects of noise on the signal-to-noise ratio (SNR) of the 8th nerve's response to small mechanical stimuli directly applied to the amphibian sacculus. We found that approximately 2.5 nm of mechanical noise enhanced the response of the saccular nerve up to fourfold, suggesting that the positive effects of low-amplitude mechanical noise result in improved transmission of acoustic information.

  12. Chloroplast Activity and 3′phosphadenosine 5′phosphate Signaling Regulate Programmed Cell Death in Arabidopsis1

    PubMed Central

    Mazubert, Christelle; Prunier, Florence; Chan, Kai Xun; Pogson, Barry James; Krieger-Liszkay, Anja; Delarue, Marianne; Benhamed, Moussa; Bergounioux, Catherine; Raynaud, Cécile

    2016-01-01

    Programmed cell death (PCD) is a crucial process both for plant development and responses to biotic and abiotic stress. There is accumulating evidence that chloroplasts may play a central role during plant PCD as for mitochondria in animal cells, but it is still unclear whether they participate in PCD onset, execution, or both. To tackle this question, we have analyzed the contribution of chloroplast function to the cell death phenotype of the myoinositol phosphate synthase1 (mips1) mutant that forms spontaneous lesions in a light-dependent manner. We show that photosynthetically active chloroplasts are required for PCD to occur in mips1, but this process is independent of the redox state of the chloroplast. Systematic genetic analyses with retrograde signaling mutants reveal that 3′-phosphoadenosine 5′-phosphate, a chloroplast retrograde signal that modulates nuclear gene expression in response to stress, can inhibit cell death and compromises plant innate immunity via inhibition of the RNA-processing 5′-3′ exoribonucleases. Our results provide evidence for the role of chloroplast-derived signal and RNA metabolism in the control of cell death and biotic stress response. PMID:26747283

  13. Homocysteine-NMDA receptor mediated activation of extracellular-signal regulated kinase leads to neuronal cell death

    PubMed Central

    Poddar, Ranjana; Paul, Surojit

    2009-01-01

    Hyper-homocysteinemia is an independent risk factor for stroke and neurological abnormalities. However the underlying cellular mechanisms by which elevated homocysteine can promote neuronal death is not clear. In the present study we have examined the role of NMDA receptor mediated activation of the extracellular-signal regulated mitogen activated protein (ERK MAP) kinase pathway in homocysteine-dependent neurotoxicity. The study demonstrates that in neurons L-homocysteine-induced cell death is mediated through activation of NMDA receptors. The study also shows that homocysteine-dependent NMDA receptor stimulation and resultant Ca2+ influx leads to rapid and sustained phosphorylation of ERK MAP kinase. Inhibition of ERK phosphorylation attenuates homocysteine mediated neuronal cell death thereby demonstrating that activation of ERK MAP kinase signaling pathway is an intermediate step that couples homocysteine mediated NMDA receptor stimulation to neuronal death. The findings also show that cAMP response-element binding protein (CREB), a pro-survival transcription factor and a downstream target of ERK, is only transiently activated following homocysteine exposure. The sustained activation of ERK but a transient activation of CREB together suggest that exposure to homocysteine initiates a feedback loop that shuts off CREB signaling without affecting ERK phosphorylation and thereby facilitates homocysteine mediated neurotoxicity. PMID:19508427

  14. Excessive L-cysteine induces vacuole-like cell death by activating endoplasmic reticulum stress and mitogen-activated protein kinase signaling in intestinal porcine epithelial cells.

    PubMed

    Ji, Yun; Wu, Zhenlong; Dai, Zhaolai; Sun, Kaiji; Zhang, Qing; Wu, Guoyao

    2016-01-01

    High intake of dietary cysteine is extremely toxic to animals and the underlying mechanism remains largely unknown. This study was conducted to test the hypothesis that excessive L-cysteine induces cell death by activating endoplasmic reticulum (ER) stress and mitogen-activated protein kinase (MAPK) signaling in intestinal porcine epithelial cells. Jejunal enterocytes were cultured in the presence of 0-10 mmol/L L-cysteine. Cell viability, morphologic alterations, mRNA levels for genes involved in ER stress, protein abundances for glucose-regulated protein 78, C/EBP homologous protein (CHOP), alpha subunit of eukaryotic initiation factor-2 (eIF2α), extracellular signal-regulated kinase (ERK1/2), p38 MAPK, and c-Jun N-terminal protein kinase (JNK1/2) were determined. The results showed that L-cysteine (5-10 mmol/L) reduced cell viability (P < 0.05) and led to vacuole-like cell death in intestinal porcine epithelial cells. These adverse effects of L-cysteine were not affected by the autophagy inhibitor 3-methyladenine. The protein abundances for CHOP, phosphorylated (p)-eIF2α, p-JNK1/2, p-p38 MAPK, and the spliced form of XBP-1 mRNA were enhanced (P < 0.05), whereas those for p-ERK1/2 were reduced (P < 0.05). Collectively, excessive L-cysteine induces vacuole-like cell death via the activation of ER stress and MAPK signaling in small intestinal epithelial cells. These signaling pathways may be potential targets for developing effective strategies to prevent the toxicity of dietary cysteine.

  15. An adaptive Kalman filter for ECG signal enhancement.

    PubMed

    Vullings, Rik; de Vries, Bert; Bergmans, Jan W M

    2011-04-01

    The ongoing trend of ECG monitoring techniques to become more ambulatory and less obtrusive generally comes at the expense of decreased signal quality. To enhance this quality, consecutive ECG complexes can be averaged triggered on the heartbeat, exploiting the quasi-periodicity of the ECG. However, this averaging constitutes a tradeoff between improvement of the SNR and loss of clinically relevant physiological signal dynamics. Using a bayesian framework, in this paper, a sequential averaging filter is developed that, in essence, adaptively varies the number of complexes included in the averaging based on the characteristics of the ECG signal. The filter has the form of an adaptive Kalman filter. The adaptive estimation of the process and measurement noise covariances is performed by maximizing the bayesian evidence function of the sequential ECG estimation and by exploiting the spatial correlation between several simultaneously recorded ECG signals, respectively. The noise covariance estimates thus obtained render the filter capable of ascribing more weight to newly arriving data when these data contain morphological variability, and of reducing this weight in cases of no morphological variability. The filter is evaluated by applying it to a variety of ECG signals. To gauge the relevance of the adaptive noise-covariance estimation, the performance of the filter is compared to that of a Kalman filter with fixed, (a posteriori) optimized noise covariance. This comparison demonstrates that, without using a priori knowledge on signal characteristics, the filter with adaptive noise estimation performs similar to the filter with optimized fixed noise covariance, favoring the adaptive filter in cases where no a priori information is available or where signal characteristics are expected to fluctuate.

  16. Ligand dependent restoration of human TLR3 signaling and death in p53 mutant cells

    PubMed Central

    Menendez, Daniel; Lowe, Julie M.; Snipe, Joyce; Resnick, Michael A.

    2016-01-01

    Diversity within the p53 transcriptional network can arise from a matrix of changes that include target response element sequences and p53 expression level variations. We previously found that wild type p53 (WT p53) can regulate expression of most innate immune-related Toll-like-receptor genes (TLRs) in human cells, thereby affecting immune responses. Since many tumor-associated p53 mutants exhibit change-of-spectrum transactivation from various p53 targets, we examined the ability of twenty-five p53 mutants to activate endogenous expression of the TLR gene family in p53 null human cancer cell lines following transfection with p53 mutant expression vectors. While many mutants retained the ability to drive TLR expression at WT levels, others exhibited null, limited, or change-of-spectrum transactivation of TLR genes. Using TLR3 signaling as a model, we show that some cancer-associated p53 mutants amplify cytokine, chemokine and apoptotic responses after stimulation by the cognate ligand poly(I:C). Furthermore, restoration of WT p53 activity for loss-of-function p53 mutants by the p53 reactivating drug RITA restored p53 regulation of TLR3 gene expression and enhanced DNA damage-induced apoptosis via TLR3 signaling. Overall, our findings have many implications for understanding the impact of WT and mutant p53 in immunological responses and cancer therapy. PMID:27533082

  17. Nanoscale Catalysts for NMR Signal Enhancement by Reversible Exchange

    PubMed Central

    2015-01-01

    Two types of nanoscale catalysts were created to explore NMR signal enhancement via reversible exchange (SABRE) at the interface between heterogeneous and homogeneous conditions. Nanoparticle and polymer comb variants were synthesized by covalently tethering Ir-based organometallic catalysts to support materials composed of TiO2/PMAA (poly(methacrylic acid)) and PVP (polyvinylpyridine), respectively, and characterized by AAS, NMR, and DLS. Following parahydrogen (pH2) gas delivery to mixtures containing one type of “nano-SABRE” catalyst particle, a target substrate, and ethanol, up to ∼(−)40-fold and ∼(−)7-fold 1H NMR signal enhancements were observed for pyridine substrates using the nanoparticle and polymer comb catalysts, respectively, following transfer to high field (9.4 T). These enhancements appear to result from intact particles and not from any catalyst molecules leaching from their supports; unlike the case with homogeneous SABRE catalysts, high-field (in situ) SABRE effects were generally not observed with the nanoscale catalysts. The potential for separation and reuse of such catalyst particles is also demonstrated. Taken together, these results support the potential utility of rational design at molecular, mesoscopic, and macroscopic/engineering levels for improving SABRE and HET-SABRE (heterogeneous-SABRE) for applications varying from fundamental studies of catalysis to biomedical imaging. PMID:26185545

  18. The Outcomes of Concentration-Specific Interactions between Salicylate and Jasmonate Signaling Include Synergy, Antagonism, and Oxidative Stress Leading to Cell Death

    PubMed Central

    Mur, Luis A.J.; Kenton, Paul; Atzorn, Rainer; Miersch, Otto; Wasternack, Claus

    2006-01-01

    Salicylic acid (SA) has been proposed to antagonize jasmonic acid (JA) biosynthesis and signaling. We report, however, that in salicylate hydroxylase-expressing tobacco (Nicotiana tabacum) plants, where SA levels were reduced, JA levels were not elevated during a hypersensitive response elicited by Pseudomonas syringae pv phaseolicola. The effects of cotreatment with various concentrations of SA and JA were assessed in tobacco and Arabidopsis (Arabidopsis thaliana). These suggested that there was a transient synergistic enhancement in the expression of genes associated with either JA (PDF1.2 [defensin] and Thi1.2 [thionin]) or SA (PR1 [PR1a-β-glucuronidase in tobacco]) signaling when both signals were applied at low (typically 10–100 μm) concentrations. Antagonism was observed at more prolonged treatment times or at higher concentrations. Similar results were also observed when adding the JA precursor, α-linolenic acid with SA. Synergic effects on gene expression and plant stress were NPR1- and COI1-dependent, SA- and JA-signaling components, respectively. Electrolyte leakage and Evans blue staining indicated that application of higher concentrations of SA + JA induced plant stress or death and elicited the generation of apoplastic reactive oxygen species. This was indicated by enhancement of hydrogen peroxide-responsive AoPR10-β-glucuronidase expression, suppression of plant stress/death using catalase, and direct hydrogen peroxide measurements. Our data suggests that the outcomes of JA-SA interactions could be tailored to pathogen/pest attack by the relative concentration of each hormone. PMID:16377744

  19. USP8 suppresses death receptor-mediated apoptosis by enhancing FLIPL stability.

    PubMed

    Jeong, M; Lee, E-W; Seong, D; Seo, J; Kim, J-H; Grootjans, S; Kim, S-Y; Vandenabeele, P; Song, J

    2017-01-26

    FLICE-like inhibitory protein (FLIP) is a critical regulator of death receptor-mediated apoptosis. Here, we found ubiquitin-specific peptidase 8 (USP8) to be a novel deubiquitylase of the long isoform of FLIP (FLIPL). USP8 directly deubiquitylates and stabilizes FLIPL, but not the short isoform. USP8 depletion induces FLIPL destabilization, promoting anti-Fas-, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)- and tumor necrosis factor alpha-induced extrinsic apoptosis by facilitating death-inducing signaling complex or TNFR1 complex II formation, which results in the activation of caspase-8 and caspase-3. USP8 mRNA levels are elevated in melanoma and cervical cancers, and the protein levels of USP8 and FLIPL are positively correlated in these cancer cell lines. Xenograft analyses using ME-180 cervical cancer cells showed that USP8 depletion attenuated tumor growth upon TRAIL injection. Taken together, our data indicate that USP8 functions as a novel deubiquitylase of FLIPL and inhibits extrinsic apoptosis by stabilizing FLIPL.

  20. Signal enhanced holographic fluorescence microscopy with guide-star reconstruction

    PubMed Central

    Jang, Changwon; Clark, David C.; Kim, Jonghyun; Lee, Byoungho; Kim, Myung K.

    2016-01-01

    We propose a signal enhanced guide-star reconstruction method for holographic fluorescence microscopy. In the late 00’s, incoherent digital holography started to be vigorously studied by several groups to overcome the limitations of conventional digital holography. The basic concept of incoherent digital holography is to acquire the complex hologram from incoherent light by utilizing temporal coherency of a spatially incoherent light source. The advent of incoherent digital holography opened new possibility of holographic fluorescence microscopy (HFM), which was difficult to achieve with conventional digital holography. However there has been an important issue of low and noisy signal in HFM which slows down the system speed and degrades the imaging quality. When guide-star reconstruction is adopted, the image reconstruction gives an improved result compared to the conventional propagation reconstruction method. The guide-star reconstruction method gives higher imaging signal-to-noise ratio since the acquired complex point spread function provides optimal system-adaptive information and can restore the signal buried in the noise more efficiently. We present theoretical explanation and simulation as well as experimental results. PMID:27446653

  1. Security Enhancement of Wireless Sensor Networks Using Signal Intervals.

    PubMed

    Moon, Jaegeun; Jung, Im Y; Yoo, Jaesoo

    2017-04-02

    Various wireless technologies, such as RF, Bluetooth, and Zigbee, have been applied to sensor communications. However, the applications of Bluetooth-based wireless sensor networks (WSN) have a security issue. In one pairing process during Bluetooth communication, which is known as simple secure pairing (SSP), the devices are required to specify I/O capability or user interference to prevent man-in-the-middle (MITM) attacks. This study proposes an enhanced SSP in which a nonce to be transferred is converted to a corresponding signal interval. The quantization level, which is used to interpret physical signal intervals, is renewed at every connection by the transferred nonce and applied to the next nonce exchange so that the same signal intervals can represent different numbers. Even if attackers eavesdrop on the signals, they cannot understand what is being transferred because they cannot determine the quantization level. Furthermore, the proposed model does not require exchanging passkeys as data, and the devices are secure in the case of using a fixed PIN. Subsequently, the new quantization level is calculated automatically whenever the same devices attempt to connect with each other. Therefore, the pairing process can be protected from MITM attacks and be convenient for users.

  2. Enhanced photoacoustic signal from DNA assembled gold nanoparticle networks

    NASA Astrophysics Data System (ADS)

    Buchkremer, A.; Beckmann, M. F.; Linn, M.; Ruff, J.; Rosencrantz, R. R.; von Plessen, G.; Schmitz, G.; Simon, U.

    2014-12-01

    We report an experimental finding of photoacoustic signal enhancement from finite sized DNA-gold nanoparticle networks. We synthesized DNA-functionalized hollow and solid gold nanospheres (AuNS) to form finite sized networks, which were characterized by means of optical extinction spectroscopy, dynamic light scattering, and scanning electron microscopy in transmission mode. It is shown that the signal amplification scales with network size for networks comprising either hollow or solid AuNS as well as networks consisting of both types of nanoparticles. The laser intensities applied in our multispectral setup (λ = 650 nm, 850 nm, 905 nm) were low enough to maintain the structural integrity of the networks. This reflects that the binding and recognition properties of the temperature-sensitive cross-linking DNA-molecules are retained.

  3. A Disease-associated Mutant of NLRC4 Shows Enhanced Interaction with SUG1 Leading to Constitutive FADD-dependent Caspase-8 Activation and Cell Death.

    PubMed

    Raghawan, Akhouri Kishore; Sripada, Anand; Gopinath, Gayathri; Pushpanjali, Pendyala; Kumar, Yatender; Radha, Vegesna; Swarup, Ghanshyam

    2017-01-27

    Nod-like receptor family card containing 4 (NLRC4)/Ipaf is involved in recognition of pathogen-associated molecular patterns leading to caspase-1 activation and cytokine release, which mediate protective innate immune response. Point mutations in NLRC4 cause autoinflammatory syndromes. Although all the mutations result in constitutive caspase-1 activation, their phenotypic presentations are different, implying that these mutations cause different alterations in properties of NLRC4. NLRC4 interacts with SUG1 and induces caspase-8-mediated cell death. Here, we show that one of the autoinflammatory syndrome-causing mutants of NLRC4, H443P, but not T337A and V341A, constitutively activates caspase-8 and induces apoptotic cell death in human lung epithelial cells. Compared with wild type NLRC4, the H443P mutant shows stronger interaction with SUG1 and with ubiquitinated cellular proteins. Phosphorylation of NLRC4 at Ser(533) plays a crucial role in caspase-8 activation and cell death. However, H443P mutant does not require Ser(533) phosphorylation for caspase-8 activation and cell death. Caspase-8 activation by NLRC4 and its H443P mutant are dependent on the adaptor protein FADD. A phosphomimicking mutant of NLRC4, S533D does not require SUG1 activity for inducing cell death. Ubiquitin-tagged NLRC4 could induce cell death and activate caspase-8 independent of Ser(533) phosphorylation. Our work suggests that SUG1-mediated signaling results in enhanced ubiquitination and regulates FADD-dependent caspase-8 activation by NLRC4. We show that the autoinflammation-associated H443P mutant is altered in interaction with SUG1 and ubiquitinated proteins, triggering constitutive caspase-8-mediated cell death dependent on FADD but independent of Ser(533) phosphorylation.

  4. Ultrasonic correlator versus signal averager as a signal to noise enhancement instrument

    NASA Technical Reports Server (NTRS)

    Kishoni, Doron; Pietsch, Benjamin E.

    1990-01-01

    Ultrasonic inspection of thick and attenuating materials is hampered by the reduce amplitudes of the propagated waves to a degree that the noise is too high to enable meaningful interpretation of the data. In order to overcome the low signal to noise ratio (S/N), a correlation technique has been developed. In this method, a continuous pseudo-random pattern generated digitally is transmitted and detected by piezoelectric transducers. A correlation is performed in the instrument between the received signal and a variable delayed image of the transmitted one. The result is shown to be proportional to the impulse response of the investigated material, analogous to a signal received from a pulsed system, with an improved S/N ratio. The degree of S/N enhancement depends on the sweep rate. The correlator is described, and it is compared to the method of enhancing S/N ratio by averaging the signals. The similarities and differences between the two are highlighted and the potential advantage of the correlator system is explained.

  5. Ultrasonic correlator versus signal averager as a signal to noise enhancement instrument

    NASA Technical Reports Server (NTRS)

    Kishoni, Doron; Pietsch, Benjamin E.

    1989-01-01

    Ultrasonic inspection of thick and attenuating materials is hampered by the reduced amplitudes of the propagated waves to a degree that the noise is too high to enable meaningful interpretation of the data. In order to overcome the low Signal to Noise (S/N) ratio, a correlation technique has been developed. In this method, a continuous pseudo-random pattern generated digitally is transmitted and detected by piezoelectric transducers. A correlation is performed in the instrument between the received signal and a variable delayed image of the transmitted one. The result is shown to be proportional to the impulse response of the investigated material, analogous to a signal received from a pulsed system, with an improved S/N ratio. The degree of S/N enhancement depends on the sweep rate. This paper describes the correlator, and compares it to the method of enhancing S/N ratio by averaging the signals. The similarities and differences between the two are highlighted and the potential advantage of the correlator system is explained.

  6. Adaptive enhancement of magnetoencephalographic signals via multichannel filtering

    SciTech Connect

    Lewis, P.S.

    1989-01-01

    A time-varying spatial/temporal filter for enhancing multichannel magnetoencephalographic (MEG) recordings of evoked responses is described. This filter is based in projections derived from a combination of measured data and a priori models of the expected response. It produces estimates of the evoked fields in single trial measurements. These estimates can reduce the need for signal averaging in some situations. The filter uses the a priori model information to enhance responses where they exist, but avoids creating responses that do not exist. Examples are included of the filter's application to both MEG single trial data containing an auditory evoked field and control data with no evoked field. 5 refs., 7 figs.

  7. Comodulation Enhances Signal Detection via Priming of Auditory Cortical Circuits

    PubMed Central

    Sollini, Joseph

    2016-01-01

    Acoustic environments are composed of complex overlapping sounds that the auditory system is required to segregate into discrete perceptual objects. The functions of distinct auditory processing stations in this challenging task are poorly understood. Here we show a direct role for mouse auditory cortex in detection and segregation of acoustic information. We measured the sensitivity of auditory cortical neurons to brief tones embedded in masking noise. By altering spectrotemporal characteristics of the masker, we reveal that sensitivity to pure tone stimuli is strongly enhanced in coherently modulated broadband noise, corresponding to the psychoacoustic phenomenon comodulation masking release. Improvements in detection were largest following priming periods of noise alone, indicating that cortical segregation is enhanced over time. Transient opsin-mediated silencing of auditory cortex during the priming period almost completely abolished these improvements, suggesting that cortical processing may play a direct and significant role in detection of quiet sounds in noisy environments. SIGNIFICANCE STATEMENT Auditory systems are adept at detecting and segregating competing sound sources, but there is little direct evidence of how this process occurs in the mammalian auditory pathway. We demonstrate that coherent broadband noise enhances signal representation in auditory cortex, and that prolonged exposure to noise is necessary to produce this enhancement. Using optogenetic perturbation to selectively silence auditory cortex during early noise processing, we show that cortical processing plays a crucial role in the segregation of competing sounds. PMID:27927950

  8. Cell death patterns in Arabidopsis cells subjected to four physiological stressors indicate multiple signalling pathways and cell cycle phase specificity.

    PubMed

    Pathirana, Ranjith; West, Phillip; Hedderley, Duncan; Eason, Jocelyn

    2017-03-01

    Corpse morphology, nuclear DNA fragmentation, expression of senescence-associated genes (SAG) and cysteine protease profiles were investigated to understand cell death patterns in a cell cycle-synchronised Arabidopsis thaliana cell suspension culture treated with four physiological stressors in the late G2 phase. Within 4 h of treatment, polyethylene glycol (PEG, 20 %), mannose (100 mM) and hydrogen peroxide (2 mM) caused DNA fragmentation coinciding with cell permeability to Evans Blue (EB) and produced corpse morphology corresponding to apoptosis-like programmed cell death (AL-PCD) with cytoplasmic retraction from the cell wall. Ethylene (8 mL per 250-mL flask) caused permeability of cells to EB without concomitant nuclear DNA fragmentation and cytoplasmic retraction, suggesting necrotic cell death. Mannose inducing glycolysis block and PEG causing dehydration resulted in relatively similar patterns of upregulation of SAG suggesting similar cell death signalling pathways for these two stress factors, whereas hydrogen peroxide caused unique patterns indicating an alternate pathway for cell death induced by oxidative stress. Ethylene did not cause appreciable changes in SAG expression, confirming necrotic cell death. Expression of AtDAD, BoMT1 and AtSAG2 genes, previously shown to be associated with plant senescence, also changed rapidly during AL-PCD in cultured cells. The profiles of nine distinct cysteine protease-active bands ranging in size from ca. 21.5 to 38.5 kDa found in the control cultures were also altered after treatment with the four stressors, with mannose and PEG again producing similar patterns. Results also suggest that cysteine proteases may have a role in necrotic cell death.

  9. Involvement of PACAP/ADNP signaling in the resistance to cell death in malignant peripheral nerve sheath tumor (MPNST) cells.

    PubMed

    Castorina, Alessandro; Giunta, Salvatore; Scuderi, Soraya; D'Agata, Velia

    2012-11-01

    Malignant peripheral nerve sheath tumors (MPNSTs) are sarcomas able to grow under conditions of metabolic stress caused by insufficient nutrients or oxygen. Both pituitary adenylate cyclase-activating polypeptide (PACAP) and activity-dependent neuroprotective protein (ADNP) have glioprotective potential. However, whether PACAP/ADNP signaling is involved in the resistance to cell death in MPNST cells remains to be clarified. Here, we investigated the involvement of this signaling system in the survival response of MPNST cells against hydrogen peroxide (H(2)O(2))-evoked death both in the presence of normal serum (NS) and in serum-starved (SS) cells. Results showed that ADNP levels increased time-dependently (6-48 h) in SS cells. Treatment with PACAP38 (10(-9) to 10(-5) M) dose-dependently increased ADNP levels in NS but not in SS cells. PAC(1)/VPAC receptor antagonists completely suppressed PACAP-stimulated ADNP increase and partially reduced ADNP expression in SS cells. NS-cultured cells exposed to H(2)O(2) showed significantly reduced cell viability (~50 %), increased p53 and caspase-3, and DNA fragmentation, without affecting ADNP expression. Serum starvation significantly reduced H(2)O(2)-induced detrimental effects in MPNST cells, which were not further ameliorated by PACAP38. Altogether, these finding provide evidence for the involvement of an endogenous PACAP-mediated ADNP signaling system that increases MPNST cell resistance to H(2)O(2)-induced death upon serum starvation.

  10. Proteomic analysis of novel targets associated with the enhancement of TrkA-induced SK-N-MC cancer cell death caused by NGF.

    PubMed

    Jung, Eun Joo; Chung, Ky Hyun; Bae, Dong-Won; Kim, Choong Won

    2016-05-27

    Nerve growth factor (NGF) is known to regulate both cancer cell survival and death signaling, depending on the cellular circumstances, in various cell types. In this study, we showed that NGF strongly upregulated the protein level of tropomyosin-related kinase A (TrkA) in TrkA-inducible SK-N-MC cancer cells, resulting in increases in various TrkA-dependent cellular processes, including the phosphorylation of c-Jun N-terminal kinase (JNK) and caspase-8 cleavage. In addition, NGF enhanced TrkA-induced morphological changes and cell death, and this effect was significantly suppressed by the JNK inhibitor SP600125, but not by the phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin. To investigate novel targets associated with the enhancement of TrkA-induced SK-N-MC cell death caused by NGF, we performed Coomassie Brilliant Blue staining and two-dimensional (2D) proteomic analysis in TrkA-inducible SK-N-MC cells. We identified 31 protein spots that were either greatly upregulated or downregulated by TrkA during NGF treatment using matrix-associated laser desorption/ionization time of flight/time of flight mass spectrometry, and we analyzed the effects of SP600125 and wortmannin on the spots. Interestingly, 11 protein spots, including heterogeneous nuclear ribonucleoprotein K (hnRNP K), lamin B1 and TAR DNA-binding protein (TDP43), were significantly influenced by SP600125, but not by wortmannin. Moreover, the NGF/TrkA-dependent inhibition of cell viability was significantly enhanced by knockdown of hnRNP K using small interfering RNA, demonstrating that hnRNP K is a novel target associated with the regulation of TrkA-dependent SK-N-MC cancer cell death enhanced by NGF.

  11. Signal quality enhancement using higher order wavelets for ultrasonic TOFD signals from austenitic stainless steel welds.

    PubMed

    Praveen, Angam; Vijayarekha, K; Abraham, Saju T; Venkatraman, B

    2013-09-01

    Time of flight diffraction (TOFD) technique is a well-developed ultrasonic non-destructive testing (NDT) method and has been applied successfully for accurate sizing of defects in metallic materials. This technique was developed in early 1970s as a means for accurate sizing and positioning of cracks in nuclear components became very popular in the late 1990s and is today being widely used in various industries for weld inspection. One of the main advantages of TOFD is that, apart from fast technique, it provides higher probability of detection for linear defects. Since TOFD is based on diffraction of sound waves from the extremities of the defect compared to reflection from planar faces as in pulse echo and phased array, the resultant signal would be quite weak and signal to noise ratio (SNR) low. In many cases the defect signal is submerged in this noise making it difficult for detection, positioning and sizing. Several signal processing methods such as digital filtering, Split Spectrum Processing (SSP), Hilbert Transform and Correlation techniques have been developed in order to suppress unwanted noise and enhance the quality of the defect signal which can thus be used for characterization of defects and the material. Wavelet Transform based thresholding techniques have been applied largely for de-noising of ultrasonic signals. However in this paper, higher order wavelets are used for analyzing the de-noising performance for TOFD signals obtained from Austenitic Stainless Steel welds. It is observed that higher order wavelets give greater SNR improvement compared to the lower order wavelets.

  12. Enhanced insulin signaling in density-enhanced phosphatase-1 (DEP-1) knockout mice

    PubMed Central

    Krüger, Janine; Brachs, Sebastian; Trappiel, Manuela; Kintscher, Ulrich; Meyborg, Heike; Wellnhofer, Ernst; Thöne-Reineke, Christa; Stawowy, Philipp; Östman, Arne; Birkenfeld, Andreas L.; Böhmer, Frank D.; Kappert, Kai

    2015-01-01

    Objective Insulin resistance can be triggered by enhanced dephosphorylation of the insulin receptor or downstream components in the insulin signaling cascade through protein tyrosine phosphatases (PTPs). Downregulating density-enhanced phosphatase-1 (DEP-1) resulted in an improved metabolic status in previous analyses. This phenotype was primarily caused by hepatic DEP-1 reduction. Methods Here we further elucidated the role of DEP-1 in glucose homeostasis by employing a conventional knockout model to explore the specific contribution of DEP-1 in metabolic tissues. Ptprj−/− (DEP-1 deficient) and wild-type C57BL/6 mice were fed a low-fat or high-fat diet. Metabolic phenotyping was combined with analyses of phosphorylation patterns of insulin signaling components. Additionally, experiments with skeletal muscle cells and muscle tissue were performed to assess the role of DEP-1 for glucose uptake. Results High-fat diet fed-Ptprj−/− mice displayed enhanced insulin sensitivity and improved glucose tolerance. Furthermore, leptin levels and blood pressure were reduced in Ptprj−/− mice. DEP-1 deficiency resulted in increased phosphorylation of components of the insulin signaling cascade in liver, skeletal muscle and adipose tissue after insulin challenge. The beneficial effect on glucose homeostasis in vivo was corroborated by increased glucose uptake in skeletal muscle cells in which DEP-1 was downregulated, and in skeletal muscle of Ptprj−/− mice. Conclusion Together, these data establish DEP-1 as novel negative regulator of insulin signaling. PMID:25830095

  13. Enhancement of new physics signal sensitivity with mistagged charm quarks

    NASA Astrophysics Data System (ADS)

    Kim, Doojin; Park, Myeonghun

    2016-07-01

    We investigate the potential for enhancing search sensitivity for signals having charm quarks in the final state, using the sizable bottom-mistagging rate for charm quarks at the LHC. Provided that the relevant background processes contain light quarks instead of charm quarks, the application of b-tagging on charm quark-initiated jets enables us to reject more background events than signal ones due to the relatively small mistagging rate for light quarks. The basic idea is tested with two rare top decay processes: i) t → ch → cb b bar and ii) t → bH+ → b b bar c where h and H+ denote the Standard Model-like higgs boson and a charged higgs boson, respectively. The major background source is a hadronic top quark decay such as t → bW+ → b s bar c. We test our method with Monte Carlo simulation at the LHC 14 TeV, and find that the signal-over-background ratio can be increased by a factor of O (6- 7) with a suitably designed (heavy) flavor tagging algorithm and scheme.

  14. Direct reconstruction of enhanced signal in computed tomography perfusion

    NASA Astrophysics Data System (ADS)

    Li, Bin; Lyu, Qingwen; Ma, Jianhua; Wang, Jing

    2016-04-01

    High imaging dose has been a concern in computed tomography perfusion (CTP) as repeated scans are performed at the same location of a patient. On the other hand, signal changes only occur at limited regions in CT acquired at different time points. In this work, we propose a new reconstruction strategy by effectively utilizing the initial phase high-quality CT to reconstruct the later phase CT acquired with a low-dose protocol. In the proposed strategy, initial high-quality CT is considered as a base image and enhanced signal (ES) is reconstructed directly by minimizing the penalized weighted least-square (PWLS) criterion. The proposed PWLS-ES strategy converts the conventional CT reconstruction into a sparse signal reconstruction problem. Digital and anthropomorphic phantom studies were performed to evaluate the performance of the proposed PWLS-ES strategy. Both phantom studies show that the proposed PWLS-ES method outperforms the standard iterative CT reconstruction algorithm based on the same PWLS criterion according to various quantitative metrics including root mean squared error (RMSE) and the universal quality index (UQI).

  15. RHOA inactivation enhances Wnt signaling and promotes colorectal cancer

    PubMed Central

    Rodrigues, Paulo; Macaya, Irati; Bazzocco, Sarah; Mazzolini, Rocco; Andretta, Elena; Dopeso, Higinio; Mateo-Lozano, Silvia; Bilić, Josipa; Cartón-García, Fernando; Nieto, Rocio; Suárez-López, Lucia; Afonso, Elsa; Landolfi, Stefania; Hernandez-Losa, Javier; Kobayashi, Kazuto; Cajal, Santiago Ramón y; Tabernero, Josep; Tebbutt, Niall C.; Mariadason, John M.; Schwartz, Simo; Arango, Diego

    2014-01-01

    Activation of the small GTPase RHOA has strong oncogenic effects in many tumor types, although its role in colorectal cancer remains unclear. Here we show that RHOA inactivation contributes to colorectal cancer progression/metastasis, largely through the activation of Wnt/β-catenin signaling. RhoA inactivation in the murine intestine accelerates the tumorigenic process and in human colon cancer cells leads to the redistribution of β-catenin from the membrane to the nucleus and enhanced Wnt/β-catenin signaling, resulting in increased proliferation, invasion and de-differentiation. In mice, RHOA inactivation contributes to colon cancer metastasis and reduced RHOA levels were observed at metastatic sites compared to primary human colon tumors. Therefore, we have identified a new mechanism of activation of Wnt/β-catenin signaling and characterized the role of RHOA as a novel tumor suppressor in colorectal cancer. These results constitute a shift from the current paradigm and demonstrate that RHO GTPases can suppress tumor progression and metastasis. PMID:25413277

  16. Salmonella typhimurium intercepts Escherichia coli signaling to enhance antibiotic tolerance

    PubMed Central

    Vega, Nicole M.; Allison, Kyle R.; Samuels, Amanda N.; Klempner, Mark S.; Collins, James J.

    2013-01-01

    Bacterial communication plays an important role in many population-based phenotypes and interspecies interactions, including those in host environments. These interspecies interactions may prove critical to some infectious diseases, and it follows that communication between pathogenic bacteria and commensal bacteria is a subject of growing interest. Recent studies have shown that Escherichia coli uses the signaling molecule indole to increase antibiotic tolerance throughout its population. Here, we show that the intestinal pathogen Salmonella typhimurium increases its antibiotic tolerance in response to indole, even though S. typhimurium does not natively produce indole. Increased antibiotic tolerance can be induced in S. typhimurium by both exogenous indole added to clonal S. typhimurium populations and indole produced by E. coli in mixed-microbial communities. Our data show that indole-induced tolerance in S. typhimurium is mediated primarily by the oxidative stress response and, to a lesser extent, by the phage shock response, which were previously shown to mediate indole-induced tolerance in E. coli. Further, we find that indole signaling by E. coli induces S. typhimurium antibiotic tolerance in a Caenorhabditis elegans model for gastrointestinal infection. These results suggest that the intestinal pathogen S. typhimurium can intercept indole signaling from the commensal bacterium E. coli to enhance its antibiotic tolerance in the host intestine. PMID:23946425

  17. MR {open_quotes}hot nose sign{close_quotes} and {open_quotes}intravascular enhancement sign{close_quotes} in brain death

    SciTech Connect

    Orrison, W.W. Jr.; Champlin, A.M.; Kesterson, O.L.; Hartshorne, M.F.; King, J.N. |

    1994-05-01

    Three cases of MR with gadopentetate dimeglumine in patients diagnosed with cerebral death are presented. Observation of an MR {open_quotes}hot nose sign{close_quotes} and an {open_quotes}intravascular enhancement sign{close_quotes} provided additional imaging support in the clinical diagnosis of brain death. The MR findings in brain death include: (1) transtentorial and foramen magnum herniation, (2) absent intracranial vascular flow void, (3) poor gray matter/white matter differentiation, (4) no intracranial contrast enhancement, (5) carotid artery enhancement (intravascular enhancement sign), and (6) prominent nasal and scalp enhancement (MR hot nose sign). Additional modalities for confirming brain death are discussed. 41 refs., 2 figs.

  18. Value of the signal-averaged electrocardiogram as a predictor of sudden death in myocardial infarction and dilated cardiomyopathy.

    PubMed

    Ohnishi, Y; Inoue, T; Fukuzaki, H

    1990-02-01

    To clarify the prognostic significance of signal averaged electrocardiogram (SAE), 100 patients with old myocardial infarction (OMI) and 54 patients with dilated cardiomyopathy (DCM) were studied. Late potentials (LPs) were detected in 31 patients with OMI and in 21 patients with DCM. During a mean follow up of 18 months (3 to 60) in OMI and 28 months (3 to 71) in DCM, 29 patients died. Fifteen patients died suddenly (8 in OMI, 7 in DCM). In OMI, the sensitivity (Se), specificity (Sp), predictive accuracy (PA) of LPs for sudden death were 75%, 72%, and 73%, respectively. The presence of either LPs or prolonged filtered QRS (f-QRS) predicted sudden death with a high Se, and the presence of both LPs and prolonged f-QRS predicted with high Sp and PA. In DCM, Se, Sp, and PA of LPs were lower than those in OMI (Se; 71%, Sp; 66%, PA; 67%). A life table analysis showed that the probability of remaining free from sudden death was significantly lower in patients with LPs than those without them in OMI, but no significant difference was observed between those with and without LPs in DCM. Patients with either LPs or prolonged f-QRS, however, had a significantly higher probability of sudden death in both diseases and no patient with normal SAE died suddenly. SAE was also useful in separating high risk patients in either normal or low cardiac index group in both diseases. Ventricular tachycardia (VT) and % fractional shortening in OMI and only VT in DCM were also useful predictors among other parameters. In conclusion, SAE provides useful information in a noninvasive method to identify patients at risk of sudden death, and patients with normal SAE have a low risk of sudden death in OMI and DCM.

  19. The Death Domain Superfamily in Intracellular Signaling of Apoptosis and Inflammation

    PubMed Central

    Park, Hyun Ho; Lo, Yu-Chih; Lin, Su-Chang; Wang, Liwei; Yang, Jin Kuk; Wu, Hao

    2010-01-01

    The death domain (DD) superfamily comprising the death domain (DD) subfamily, the death effector domain (DED) subfamily, the caspase recruitment domain (CARD) subfamily and the pyrin domains (PYD) subfamily is one of the largest domain superfamilies. By mediating homotypic interactions within each domain subfamily, these proteins play important roles in the assembly and activation of apoptotic and inflammatory complexes. In this article, we review the molecular complexes that are assembled by these proteins, the structural and biochemical features of these domains and the molecular interactions mediated by them. By analyzing the potential molecular basis for the function of these domains, we hope to provide a comprehensive understanding on the function, structure, interaction and evolution of this important family of domains. PMID:17201679

  20. Caspase Inhibition Blocks Cell Death and Enhances Mitophagy but Fails to Promote T-Cell Lymphoma

    PubMed Central

    Wang, Sih-han; Martin, Sean M.; Harris, Peter S.; Knudson, C. Michael

    2011-01-01

    Caspase-9 is a component of the apoptosome that mediates cell death following release of cytochrome c from mitochondria. Inhibition of Caspase-9 with a dominant negative construct (Casp9DN) blocks apoptosome function, promotes viability and has been implicated in carcinogenesis. Inhibition of the apoptosome in vitro impairs mitochondrial function and promotes mitophagy. To examine whether inhibition of the apoptosome would enhance mitophagy and promote oncogenesis in vivo, transgenic mice were generated that express Casp9DN in the T cell lineage. The effects of Casp9DN on thymocyte viability, mitophagy and thymic tumor formation were examined. In primary thymocytes, Casp9DN delayed dexamethasone (Dex)-induced cell death, altered mitochondrial structure, and decreased oxidant production. Transmission electron microscopy (TEM) revealed that inhibition of the apoptosome resulted in structurally abnormal mitochondria that in some cases were engulfed by double-membrane structures resembling autophagosomes. Consistent with mitochondria being engulfed by autophagosomes (mitophagy), confocal microscopy showed colocalization of LC3-GFP and mitochondria. However, Casp9DN did not significantly accelerate T-cell lymphoma alone, or in combination with Lck-Bax38/1, or with Beclin 1+/− mice, two tumor-prone strains in which altered mitochondrial function has been implicated in promoting tumor development. In addition, heterozygous disruption of Beclin 1 had no effect on T-cell lymphoma formation in Lck-Bax38/1 mice. Further studies showed that Beclin 1 levels had no effect on Casp9DN-induced loss of mitochondrial function. These results demonstrate that neither inhibition of apoptosome function nor Beclin 1 haploinsufficiency accelerate T-cell lymphoma development in mice. PMID:21611191

  1. Neuroprotective Strategy in Retinal Degeneration: Suppressing ER Stress-Induced Cell Death via Inhibition of the mTOR Signal

    PubMed Central

    Fan, Bin; Sun, Ying-Jian; Liu, Shu-Yan; Che, Lin; Li, Guang-Yu

    2017-01-01

    The retina is a specialized sensory organ, which is essential for light detection and visual formation in the human eye. Inherited retinal degenerations are a heterogeneous group of eye diseases that can eventually cause permanent vision loss. UPR (unfolded protein response) and ER (endoplasmic reticulum) stress plays an important role in the pathological mechanism of retinal degenerative diseases. mTOR (the mammalian target of rapamycin) kinase, as a signaling hub, controls many cellular processes, covering protein synthesis, RNA translation, ER stress, and apoptosis. Here, the hypothesis that inhibition of mTOR signaling suppresses ER stress-induced cell death in retinal degenerative disorders is discussed. This review surveys knowledge of the influence of mTOR signaling on ER stress arising from misfolded proteins and genetic mutations in retinal degenerative diseases and highlights potential neuroprotective strategies for treatment and therapeutic implications. PMID:28106827

  2. Ex vivo Perfusion with Adenosine A2A Receptor Agonist Enhances Rehabilitation of Murine Donor Lungs after Circulatory Death

    PubMed Central

    Stone, Mathew L.; Sharma, Ashish K.; Mas, Valeria. R.; Gehrau, Ricardo C.; Mulloy, Daniel P.; Zhao, Yunge; Lau, Christine L.; Kron, Irving L.; Laubach, Victor E.

    2015-01-01

    Background Ex vivo lung perfusion (EVLP) enables assessment and rehabilitation of marginal donor lungs prior to transplantation. We previously demonstrated that adenosine A2A receptor (A2AR) agonism attenuates lung ischemia-reperfusion injury. The current study utilizes a novel murine EVLP model to test the hypothesis that A2AR agonist enhances EVLP-mediated rehabilitation of donation after circulatory death (DCD) lungs. Methods Mice underwent euthanasia and 60 min warm ischemia, and lungs were flushed with Perfadex and underwent cold static preservation (CSP, 60 min). Three groups were studied: no EVLP (CSP), EVLP with Steen solution for 60 min (EVLP), and EVLP with Steen solution supplemented with ATL1223, a selective A2AR agonist (EVLP+ATL1223). Lung function, wet/dry weight, cytokines and neutrophil numbers were measured. Microarrays were performed using the Affymetrix GeneChip Mouse Genome 430A 2.0 Array. Results EVLP significantly improved lung function versus CSP, which was further, significantly improved by EVLP+ATL1223. Lung edema, cytokines and neutrophil counts were reduced after EVLP and further, significantly reduced after EVLP+ATL1223. Gene array analysis revealed differential expression of 1,594 genes after EVLP, which comprise canonical pathways involved in inflammation and innate immunity including IL-1, IL-8, IL-6 and IL-17 signaling. Several pathways were uniquely regulated by EVLP+ATL1223 including the downregulation of genes involved in IL-1 signaling such as ADCY9, ECSIT, IRAK1, MAPK12 and TOLLIP. Conclusion EVLP modulates pro-inflammatory genes and reduces pulmonary dysfunction, edema and inflammation in DCD lungs, which are further reduced by A2AR agonism. This murine EVLP model provides a novel platform to study rehabilitative mechanisms of DCD lungs. PMID:26262504

  3. Cannabidiol enhances anandamide signaling and alleviates psychotic symptoms of schizophrenia.

    PubMed

    Leweke, F M; Piomelli, D; Pahlisch, F; Muhl, D; Gerth, C W; Hoyer, C; Klosterkötter, J; Hellmich, M; Koethe, D

    2012-03-20

    Cannabidiol is a component of marijuana that does not activate cannabinoid receptors, but moderately inhibits the degradation of the endocannabinoid anandamide. We previously reported that an elevation of anandamide levels in cerebrospinal fluid inversely correlated to psychotic symptoms. Furthermore, enhanced anandamide signaling let to a lower transition rate from initial prodromal states into frank psychosis as well as postponed transition. In our translational approach, we performed a double-blind, randomized clinical trial of cannabidiol vs amisulpride, a potent antipsychotic, in acute schizophrenia to evaluate the clinical relevance of our initial findings. Either treatment was safe and led to significant clinical improvement, but cannabidiol displayed a markedly superior side-effect profile. Moreover, cannabidiol treatment was accompanied by a significant increase in serum anandamide levels, which was significantly associated with clinical improvement. The results suggest that inhibition of anandamide deactivation may contribute to the antipsychotic effects of cannabidiol potentially representing a completely new mechanism in the treatment of schizophrenia.

  4. Melatonin enhances arsenic trioxide-induced cell death via sustained upregulation of Redd1 expression in breast cancer cells.

    PubMed

    Yun, Sun-Mi; Woo, Sang Hyeok; Oh, Sang Taek; Hong, Sung-Eun; Choe, Tae-Boo; Ye, Sang-Kyu; Kim, Eun-Kyu; Seong, Min Ki; Kim, Hyun-A; Noh, Woo Chul; Lee, Jin Kyung; Jin, Hyeon-Ok; Lee, Yun-Han; Park, In-Chul

    2016-02-15

    Melatonin is implicated in various physiological functions, including anticancer activity. However, the mechanism(s) of its anticancer activity is not well understood. In the present study, we investigated the combined effects of melatonin and arsenic trioxide (ATO) on cell death in human breast cancer cells. Melatonin enhanced the ATO-induced apoptotic cell death via changes in the protein levels of Survivin, Bcl-2, and Bax, thus affecting cytochrome c release from the mitochondria to the cytosol. Interestingly, we found that the cell death induced by co-treatment with melatonin and ATO was mediated by sustained upregulation of Redd1, which was associated with increased production of reactive oxygen species (ROS). Combined treatment with melatonin and ATO induced the phosphorylation of JNK and p38 MAP kinase downstream from Redd1 expression. Rapamycin and S6K1 siRNA enhanced, while activation of mTORC1 by transfection with TSC2 siRNA suppressed the cell death induced by melatonin and ATO treatment. Taken together, our findings suggest that melatonin enhances ATO-induced apoptotic cell death via sustained upregulation of Redd1 expression and inhibition of mTORC1 upstream of the activation of the p38/JNK pathways in human breast cancer cells.

  5. Local erythropoietin signaling enhances regeneration in peripheral axons.

    PubMed

    Toth, C; Martinez, J A; Liu, W Q; Diggle, J; Guo, G F; Ramji, N; Mi, R; Hoke, A; Zochodne, D W

    2008-06-23

    Erythropoietin (EPO) and its receptor (EPO-R), mediate neuroprotection from axonopathy and apoptosis in the peripheral nervous system (PNS). We examined the impact and potential mechanisms of local EPO signaling on regenerating PNS axons in vivo and in vitro. As a consequence of injury, peripheral nerve axons and DRG neurons have a marked increase in the expression of EPO and EPO-R. Local delivery of EPO via conduit over 2 weeks to rat sciatic nerve following crush injury increased the density and maturity of regenerating myelinated axons growing distally from the crush site. In addition, EPO also rescued retrograde degeneration and atrophy of axons. EPO substantially increased the density and intensity of calcitonin gene-related peptide (CGRP) expression within outgrowing axons. Behavioral improvements in sensorimotor function also occurred in rats exposed to near nerve EPO delivery. EPO delivery led to decreased nuclear factor kappaB (NFkB) activation but increased phosphorylation of Akt and STAT3 within nerve and dorsal root ganglia neurons indicating rescue from an injury phenotype. Spinal cord explant studies also demonstrated a similar dose-dependent effect of EPO upon motor axonal outgrowth. Local EPO signaling enhances regenerating peripheral nervous system axons in addition to its known neuroprotection. Exogenous EPO may have a therapeutic role in a large number of peripheral nerve diseases through its impact on regeneration.

  6. Static corrections for enhanced signal detection at IMS seismic arrays

    NASA Astrophysics Data System (ADS)

    Wilkins, Neil; Wookey, James; Selby, Neil

    2016-04-01

    Seismic monitoring forms an important part of the International Monitoring System (IMS) for verifying the Comprehensive nuclear Test Ban Treaty (CTBT). Analysis of seismic data can be used to discriminate between nuclear explosions and the tens of thousands of natural earthquakes of similar magnitude that occur every year. This is known as "forensic seismology", and techniques include measuring the P-to-S wave amplitude ratio, the body-to-surface wave magnitude ratio (mb/Ms), and source depth. Measurement of these seismic discriminants requires very high signal-to-noise ratio (SNR) data, and this has led to the development and deployment of seismic arrays as part of the IMS. Array processing methodologies such as stacking can be used, but optimum SNR improvement needs an accurate estimate of the arrival time of the particular seismic phase. To enhance the imaging capability of IMS arrays, we aim to develop site-specific static corrections to the arrival time as a function of frequency, slowness and backazimuth. Here, we present initial results for the IMS TORD array in Niger. Vespagrams are calculated for various events using the F-statistic to clearly identify seismic phases and measure their arrival times. Observed arrival times are compared with those predicted by 1D and 3D velocity models, and residuals are calculated for a range of backazimuths and slownesses. Finally, we demonstrate the improvement in signal fidelity provided by these corrections.

  7. Graphene Nanogrids FET Immunosensor: Signal to Noise Ratio Enhancement

    PubMed Central

    Basu, Jayeeta; RoyChaudhuri, Chirasree

    2016-01-01

    Recently, a reproducible and scalable chemical method for fabrication of smooth graphene nanogrids has been reported which addresses the challenges of graphene nanoribbons (GNR). These nanogrids have been found to be capable of attomolar detection of biomolecules in field effect transistor (FET) mode. However, for detection of sub-femtomolar concentrations of target molecule in complex mixtures with reasonable accuracy, it is not sufficient to only explore the steady state sensitivities, but is also necessary to investigate the flicker noise which dominates at frequencies below 100 kHz. This low frequency noise is dependent on the exposure time of the graphene layer in the buffer solution and concentration of charged impurities at the surface. In this paper, the functionalization strategy of graphene nanogrids has been optimized with respect to concentration and incubation time of the cross linker for an enhancement in signal to noise ratio (SNR). It has been interestingly observed that as the sensitivity and noise power change at different rates with the functionalization parameters, SNR does not vary monotonically but is maximum corresponding to a particular parameter. The optimized parameter has improved the SNR by 50% which has enabled a detection of 0.05 fM Hep-B virus molecules with a sensitivity of around 30% and a standard deviation within 3%. Further, the SNR enhancement has resulted in improvement of quantification accuracy by five times and selectivity by two orders of magnitude. PMID:27740605

  8. Signaling Pathways that Mediate Neurotoxin-Induced Death of Dopamine Neurons

    DTIC Science & Technology

    2005-11-01

    undergoing apoptosis. Cell Death and Differentiation, 12: 255-265, 2005. 5. Zimmermann, AK, FA Loucks , SS Le, BD Butts, M McClure, RJ Bouchard, KA...279-289, 2005. 7. Le, SS, FA Loucks , H Udo, S Richardson-Burns, RA Phelps, RJ Bouchard, H Barth, K Aktories, KL Tyler, ER Kandel, KA Heidenreich...Apoptosis in Biochemistry and Structural Biology. 2004 2. Loucks FA, Zimmermann AK, Le SS, Bouchard RJ, Laessig TA, Heidenreich KA, and Linseman DA

  9. Lipid rafts and raft-mediated supramolecular entities in the regulation of CD95 death receptor apoptotic signaling.

    PubMed

    Gajate, Consuelo; Mollinedo, Faustino

    2015-05-01

    Membrane lipid rafts are highly ordered membrane domains enriched in cholesterol, sphingolipids and gangliosides that have the property to segregate and concentrate proteins. Lipid and protein composition of lipid rafts differs from that of the surrounding membrane, thus providing sorting platforms and hubs for signal transduction molecules, including CD95 death receptor-mediated signaling. CD95 can be recruited to rafts in a reversible way through S-palmitoylation following activation of cells with its physiological cognate ligand as well as with a wide variety of inducers, including several antitumor drugs through ligand-independent intracellular mechanisms. CD95 translocation to rafts can be modulated pharmacologically, thus becoming a target for the treatment of apoptosis-defective diseases, such as cancer. CD95-mediated signaling largely depends on protein-protein interactions, and the recruitment and concentration of CD95 and distinct downstream apoptotic molecules in membrane raft domains, forming raft-based supramolecular entities that act as hubs for apoptotic signaling molecules, favors the generation and amplification of apoptotic signals. Efficient CD95-mediated apoptosis involves CD95 and raft internalization, as well as the involvement of different subcellular organelles. In this review, we briefly summarize and discuss the involvement of lipid rafts in the regulation of CD95-mediated apoptosis that may provide a new avenue for cancer therapy.

  10. Local readout enhancement for detuned signal-recycling interferometers

    SciTech Connect

    Rehbein, Henning; Mueller-Ebhardt, Helge; Schnabel, Roman; Danzmann, Karsten; Somiya, Kentaro; Chen Yanbei; Li Chao

    2007-09-15

    High power detuned signal-recycling interferometers currently planned for second-generation interferometric gravitational-wave detectors (for example Advanced LIGO) are characterized by two resonances in the detection band, an optical resonance and an optomechanical resonance which is upshifted from the suspension pendulum frequency due to the so-called optical-spring effect. The detector's sensitivity is enhanced around these two resonances. However, at frequencies below the optomechanical resonance frequency, the sensitivity of such interferometers is significantly lower than non-optical-spring configurations with comparable circulating power; such a drawback can also compromise high-frequency sensitivity, when an optimization is performed on the overall sensitivity of the interferometer to a class of sources. In this paper, we clarify the reason for such a low sensitivity, and propose a way to fix this problem. Motivated by the optical-bar scheme of Braginsky, Gorodetsky, and Khalili, we propose to add a local readout scheme which measures the motion of the arm-cavity front mirror, which at low frequencies moves together with the arm-cavity end mirror, under the influence of gravitational waves. This scheme improves the low-frequency quantum-noise-limited sensitivity of optical-spring interferometers significantly and can be considered as an incorporation of the optical-bar scheme into currently planned second-generation interferometers. On the other hand it can be regarded as an extension of the optical-bar scheme. Taking compact binary inspiral signals as an example, we illustrate how this scheme can be used to improve the sensitivity of the planned Advanced LIGO interferometer, in various scenarios, using a realistic classical-noise budget. We also discuss how this scheme can be implemented in Advanced LIGO with relative ease.

  11. Fisetin induces autophagic cell death through suppression of mTOR signaling pathway in prostate cancer cells

    PubMed Central

    Suh, Yewseok; Afaq, Farrukh; Khan, Naghma; Johnson, Jeremy J.; Khusro, Fatima H.; Mukhtar, Hasan

    2010-01-01

    The mammalian target of rapamycin (mTOR) kinase is an important component of PTEN/PI3K/Akt signaling pathway, which is frequently deregulated in prostate cancer (CaP). Recent studies suggest that targeting PTEN/PI3K/Akt and mTOR signaling pathway could be an effective strategy for the treatment of hormone refractory CaP. Here, we show that the treatment of androgen-independent and PTEN-negative human CaP PC3 cells with fisetin, a dietary flavonoid, resulted in inhibition of mTOR kinase signaling pathway. Treatment of cells with fisetin inhibited mTOR activity and downregulated Raptor, Rictor, PRAS40 and GβL that resulted in loss of mTOR complexes (mTORC)1/2 formation. Fisetin also activated the mTOR repressor TSC2 through inhibition of Akt and activation of AMPK. Fisetin-mediated inhibition of mTOR resulted in hypophosphorylation of 4EBP1 and suppression of Cap-dependent translation. We also found that fisetin treatment leads to induction of autophagic-programmed cell death rather than cytoprotective autophagy as shown by small interfering RNA Beclin1-knockdown and autophagy inhibitor. Taken together, we provide evidence that fisetin functions as a dual inhibitor of mTORC1/2 signaling leading to inhibition of Cap-dependent translation and induction of autophagic cell death in PC3 cells. These results suggest that fisetin could be a useful chemotherapeutic agent in treatment of hormone refractory CaP. PMID:20530556

  12. Death and survival in Streptococcus mutans: differing outcomes of a quorum-sensing signaling peptide.

    PubMed

    Leung, Vincent; Dufour, Delphine; Lévesque, Céline M

    2015-01-01

    Bacteria are considered "social" organisms able to communicate with one another using small hormone-like molecules (pheromones) in a process called quorum-sensing (QS). These signaling molecules increase in concentration as a function of bacterial cell density. For most human pathogens, QS is critical for virulence and biofilm formation, and the opportunity to interfere with bacterial QS could provide a sophisticated means for manipulating the composition of pathogenic biofilms, and possibly eradicating the infection. Streptococcus mutans is a well-characterized resident of the dental plaque biofilm, and is the major pathogen of dental caries (cavities). In S. mutans, its CSP QS signaling peptide does not act as a classical QS signal by accumulating passively in proportion to cell density. In fact, particular stresses such as those encountered in the oral cavity, induce the production of the CSP pheromone, suggesting that the pheromone most probably functions as a stress-inducible alarmone by triggering the signaling to the bacterial population to initiate an adaptive response that results in different phenotypic outcomes. This mini-review discusses two different CSP-induced phenotypes, bacterial "suicide" and dormancy, and the underlying mechanisms by which S. mutans utilizes the same QS signaling peptide to regulate two opposite phenotypes.

  13. Enhanced line signals from annihilating Kaluza-Klein dark matter

    NASA Astrophysics Data System (ADS)

    Arina, Chiara; Bringmann, Torsten; Silk, Joseph; Vollmann, Martin

    2014-10-01

    Monochromatic gamma ray lines have long been known to provide potential smoking-gun signals for annihilating dark matter. Here, we demonstrate that the situation is particularly interesting for Kaluza-Klein dark matter because resonant annihilation is generically expected for small, but not necessarily vanishing relative velocities of the annihilating particles. We calculate the contribution from those hitherto neglected resonances and show that the annihilation rate into monochromatic photons can be significantly enhanced, in a way that is much more pronounced than for the associated production of continuum photons. For favorable astrophysical conditions, this leads to promising prospects for the detection of TeV-scale Kaluza-Klein dark matter. We also point out that the situation may be even more interesting in the vicinity of black holes, like the supermassive black hole at the center of our Galaxy, where in principle center-of-mass energies much larger than the rest mass are available. In this case, annihilating Kaluza-Klein dark matter may show the striking and unique signature of several gamma ray lines, with an equidistant spacing corresponding to twice the compactification radius of the extra dimension.

  14. Delicaflavone induces autophagic cell death in lung cancer via Akt/mTOR/p70S6K signaling pathway.

    PubMed

    Sui, Yuxia; Yao, Hong; Li, Shaoguang; Jin, Long; Shi, Peiying; Li, Zhijun; Wang, Gang; Lin, Shilan; Wu, Youjia; Li, Yuxiang; Huang, Liying; Liu, Qicai; Lin, Xinhua

    2017-03-01

    Searching for potential anticancer agents from natural sources is an effective strategy for developing novel chemotherapeutic agents. In this study, data supporting the in vitro and in vivo anticancer effects of delicaflavone, a rarely occurring biflavonoid from Selaginella doederleinii, were reported. Delicaflavone exhibited favorable anticancer properties, as shown by the MTT assay and xenograft model of human non-small cell lung cancer in male BALB/c nude mice without observable adverse effect. By transmission electron microscopy with acridine orange and Cyto-ID®Autophagy detection dyes, Western blot analysis, and RT-PCR assay, we confirmed that delicaflavone induces autophagic cell death by increasing the ratio of LC3-II to LC3-I, which are autophagy-related proteins, and promoting the generation of acidic vesicular organelles and autolysosomes in the cytoplasm of human lung cancer A549 and PC-9 cells in a time- and dose-dependent manner. Delicaflavone downregulated the expression of phospho-Akt, phospho-mTOR, and phospho-p70S6K in a time- and dose-dependent manner, suggesting that it induced autophagy by inhibiting the Akt/mTOR/p70S6K pathway in A549 and PC-9 cells. Delicaflavone is a potential anticancer agent that can induce autophagic cell death in human non-small cell lung cancer via the Akt/mTOR/p70S6K signaling pathway. Delicaflavone showed anti-lung cancer effects in vitro and in vivo. Delicaflavone induced autophagic cell death via Akt/mTOR/p70S6K signaling pathway. Delicaflavone did not show observable side effects in a xenograft mouse model. Delicaflavone may represent a potential therapeutic agent for lung cancer.

  15. Novel role for mitochondria: protein kinase Ctheta-dependent oxidative signaling organelles in activation-induced T-cell death.

    PubMed

    Kaminski, Marcin; Kiessling, Michael; Süss, Dorothee; Krammer, Peter H; Gülow, Karsten

    2007-05-01

    Reactive oxygen species (ROS) play a key role in regulation of activation-induced T-cell death (AICD) by induction of CD95L expression. However, the molecular source and the signaling steps necessary for ROS production are largely unknown. Here, we show that the proximal T-cell receptor-signaling machinery, including ZAP70 (zeta chain-associated protein kinase 70), LAT (linker of activated T cells), SLP76 (SH2 domain-containing leukocyte protein of 76 kDa), PLCgamma1 (phospholipase Cgamma1), and PKCtheta (protein kinase Ctheta), are crucial for ROS production. PKCtheta is translocated to the mitochondria. By using cells depleted of mitochondrial DNA, we identified the mitochondria as the source of activation-induced ROS. Inhibition of mitochondrial electron transport complex I assembly by small interfering RNA (siRNA)-mediated knockdown of the chaperone NDUFAF1 resulted in a block of ROS production. Complex I-derived ROS are converted into a hydrogen peroxide signal by the mitochondrial superoxide dismutase. This signal is essential for CD95L expression, as inhibition of complex I assembly by NDUFAF1-specific siRNA prevents AICD. Similar results were obtained when metformin, an antidiabetic drug and mild complex I inhibitor, was used. Thus, we demonstrate for the first time that PKCtheta-dependent ROS generation by mitochondrial complex I is essential for AICD.

  16. Chronic blockade of extrasynaptic NMDA receptors ameliorates synaptic dysfunction and pro-death signaling in Huntington disease transgenic mice.

    PubMed

    Dau, Alejandro; Gladding, Clare M; Sepers, Marja D; Raymond, Lynn A

    2014-02-01

    In the YAC128 mouse model of Huntington disease (HD), elevated extrasynaptic NMDA receptor (Ex-NMDAR) expression contributes to the onset of striatal dysfunction and atrophy. A shift in the balance of synaptic-extrasynaptic NMDAR signaling and localization is paralleled by early stage dysregulation of intracellular calcium signaling pathways, including calpain and p38 MAPK activation, that couple to pro-death cascades. However, whether aberrant calcium signaling is a consequence of elevated Ex-NMDAR expression in HD is unknown. Here, we aimed to identify calcium-dependent pathways downstream of Ex-NMDARs in HD. Chronic (2-month) treatment of YAC128 and WT mice with memantine (1 and 10mg/kg/day), which at a low dose selectively blocks Ex-NMDARs, reduced striatal Ex-NMDAR expression and current in 4-month old YAC128 mice without altering synaptic NMDAR levels. In contrast, calpain activity was not affected by memantine treatment, and was elevated in untreated YAC128 mice at 1.5months but not 4months of age. In YAC128 mice, memantine at 1mg/kg/day rescued CREB shut-off, while both doses suppressed p38 MAPK activation to WT levels. Taken together, our results indicate that Ex-NMDAR activity perpetuates increased extrasynaptic NMDAR expression and drives dysregulated p38 MAPK and CREB signaling in YAC128 mice. Elucidation of the pathways downstream of Ex-NMDARs in HD could help provide novel therapeutic targets for this disease.

  17. From intracellular signaling networks to cell death: the dual role of reactive oxygen species in seed physiology.

    PubMed

    Bailly, Christophe; El-Maarouf-Bouteau, Hayat; Corbineau, Françoise

    2008-10-01

    Reactive Oxygen Species (ROS) are continuously produced during seed development, from embryogenesis to germination, but also during seed storage. ROS play a dual role in seed physiology behaving, on the one hand, as actors of cellular signaling pathways and, on the other hand, as toxic products that accumulate under stress conditions. ROS, provided that their amount is tightly regulated by the balance between production and scavenging, appear now as being beneficial for germination, and in particular to act as a positive signal for seed dormancy release. Such an effect might result from the interplay between ROS and hormone signaling pathways thus leading to changes in gene expression or in cellular redox status. We also propose that changes in ROS homeostasis would play a role in perception of environmental factors by seeds during their germination, and thus act as a signal controlling the completion of germination. However, uncontrolled accumulation of ROS is likely to occur during seed aging or seed desiccation thus leading to oxidative damage toward a wide range of biomolecules and ultimately to necroses and cell death. We present here the concept of the "oxidative window for germination", which restricts the occurrence of the cellular events associated with germination to a critical range of ROS level, enclosed by lower and higher limits. Above or below the "oxidative window for germination", weak or high amounts of ROS, respectively, would not permit progress toward germination.

  18. Reduced hippocampal manganese-enhanced MRI (MEMRI) signal during pilocarpine-induced status epilepticus: edema or apoptosis?

    PubMed

    Malheiros, Jackeline Moraes; Persike, Daniele Suzete; Castro, Leticia Urbano Cardoso de; Sanches, Talita Rojas Cunha; Andrade, Lúcia da Conceição; Tannús, Alberto; Covolan, Luciene

    2014-05-01

    Manganese-enhanced MRI (MEMRI) has been considered a surrogate marker of Ca(+2) influx into activated cells and tracer of neuronal active circuits. However, the induction of status epilepticus (SE) by kainic acid does not result in hippocampal MEMRI hypersignal, in spite of its high cell activity. Similarly, short durations of status (5 or 15min) induced by pilocarpine did not alter the hippocampal MEMRI, while 30 min of SE even reduced MEMRI signal Thus, this study was designed to investigate possible explanations for the absence or decrease of MEMRI signal after short periods of SE. We analyzed hippocampal caspase-3 activation (to evaluate apoptosis), T2 relaxometry (tissue water content) and aquaporin 4 expression (water-channel protein) of rats subjected to short periods of pilocarpine-induced SE. For the time periods studied here, apoptotic cell death did not contribute to the decrease of the hippocampal MEMRI signal. However, T2 relaxation was higher in the group of animals subjected to 30min of SE than in the other SE or control groups. This result is consistent with higher AQP-4 expression during the same time period. Based on apoptosis and tissue water content analysis, the low hippocampal MEMRI signal 30min after SE can potentially be attributed to local edema rather than to cell death.

  19. Blockade of PD-1 Signaling Enhances Th2 Cell Responses and Aggravates Liver Immunopathology in Mice with Schistosomiasis japonica

    PubMed Central

    Zhou, Sha; Jin, Xin; Li, Yalin; Li, Wei; Chen, Xiaojun; Xu, Lei; Zhu, Jifeng; Xu, Zhipeng; Zhang, Yang; Liu, Feng; Su, Chuan

    2016-01-01

    Background More than 220 million people worldwide are chronically infected with schistosomes, causing severe disease or even death. The major pathological damage occurring in schistosomiasis is attributable to the granulomatous inflammatory response and liver fibrosis induced by schistosome eggs. The inflammatory response is tightly controlled and parallels immunosuppressive regulation, constantly maintaining immune homeostasis and limiting excessive immunopathologic damage in important host organs. It is well known that the activation of programmed death 1 (PD-1) signaling causes a significant suppression of T cell function. However, the roles of PD-1 signaling in modulating CD4+ T cell responses and immunopathology during schistosome infection, have yet to be defined. Methodology/Principal Findings Here, we show that PD-1 is upregulated in CD4+ T cells in Schistosoma japonicum (S. japonicum)-infected patients. We also show the upregulation of PD-1 expression in CD4+ T cells in the spleens, mesenteric lymph nodes, and livers of mice with S. japonicum infection. Finally, we found that the blockade of PD-1 signaling enhanced CD4+ T helper 2 (Th2) cell responses and led to more severe liver immunopathology in mice with S. japonicum infection, without a reduction of egg production or deposition in the host liver. Conclusions/Significance Overall, our study suggests that PD-1 signaling is specifically induced to control Th2-associated inflammatory responses during schistosome infection and is beneficial to the development of PD-1-based control of liver immunopathology. PMID:27792733

  20. Polycyclic aromatic hydrocarbons enhance terminal cell death of human ectocervical cells.

    PubMed

    Rorke, E A; Sizemore, N; Mukhtar, H; Couch, L H; Howard, P C

    1998-09-01

    Polycyclic aromatic hydrocarbons (PAH) are a class of chemical carcinogens whose active metabolites form DNA adducts, resulting in specific mutational events. The tumor suppressor protein p53 is believed to play a pivotal role in the ability of cells to response to DNA damage, resulting in either cell cycle arrest in G1 or apoptosis under conditions of excessive damage. This growth inhibition is associated with the concomitant induction of p53 and enhanced terminal cell differentiation. In this study we evaluated the effects of PAH on cell growth, cell differentiation, xenobiotic metabolism, and DNA adduct levels in normal ectocervical epithelial cells (ECE) and compared them to cervical cells whose p53 have been inactivated either by binding to viral HPV E6 oncogene (ECE16-1) or by mutation (C33A). The PAH 3-methylcholanthrene (3MC) inhibited normal ECE and to a lesser extent ECE16-1 cell proliferation. Not only did the growth inhibition occur at lower concentrations in the normal cells but the extent of inhibition was also greater in normal as compared to immortalized cells. Benzanthracene (BA) had a minor effect on normal ECE cells with no effect on immortalized ECE16-1 cells. C33A cell growth was unaffected by 3MC and BA. Terminal cell death was enhanced only in normal ECE cells as evidenced by increased envelope formation and was paralleled by an increase in the level of p53 following 3MC treatment. The differentiation status of the 3MC-treated cells was similar to untreated cells as indicated by three independent markers of cell differentiation; transglutaminase, involucrin, keratin expression. There was no difference in the pattern or level of DNA adducts formed in normal and immortalized cells following 3MC treatment. In addition the basal level of metabolism of 14C-BaP to phenols, diols and quinnones was unaltered by pretreatment with either 3MC or BA. These results demonstrate that immortalized cervical cells are less sensitive to toxicant damage [i

  1. Reactive oxygen species trigger motoneuron death in non-cell-autonomous models of ALS through activation of c-Abl signaling.

    PubMed

    Rojas, Fabiola; Gonzalez, David; Cortes, Nicole; Ampuero, Estibaliz; Hernández, Diego E; Fritz, Elsa; Abarzua, Sebastián; Martinez, Alexis; Elorza, Alvaro A; Alvarez, Alejandra; Court, Felipe; van Zundert, Brigitte

    2015-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease in which pathogenesis and death of motor neurons are triggered by non-cell-autonomous mechanisms. We showed earlier that exposing primary rat spinal cord cultures to conditioned media derived from primary mouse astrocyte conditioned media (ACM) that express human SOD1(G93A) (ACM-hSOD1(G93A)) quickly enhances Nav channel-mediated excitability and calcium influx, generates intracellular reactive oxygen species (ROS), and leads to death of motoneurons within days. Here we examined the role of mitochondrial structure and physiology and of the activation of c-Abl, a tyrosine kinase that induces apoptosis. We show that ACM-hSOD1(G93A), but not ACM-hSOD1(WT), increases c-Abl activity in motoneurons, interneurons and glial cells, starting at 60 min; the c-Abl inhibitor STI571 (imatinib) prevents this ACM-hSOD1(G93A)-mediated motoneuron death. Interestingly, similar results were obtained with ACM derived from astrocytes expressing SOD1(G86R) or TDP43(A315T). We further find that co-application of ACM-SOD1(G93A) with blockers of Nav channels (spermidine, mexiletine, or riluzole) or anti-oxidants (Trolox, esculetin, or tiron) effectively prevent c-Abl activation and motoneuron death. In addition, ACM-SOD1(G93A) induces alterations in the morphology of neuronal mitochondria that are related with their membrane depolarization. Finally, we find that blocking the opening of the mitochondrial permeability transition pore with cyclosporine A, or inhibiting mitochondrial calcium uptake with Ru360, reduces ROS production and c-Abl activation. Together, our data point to a sequence of events in which a toxic factor(s) released by ALS-expressing astrocytes rapidly induces hyper-excitability, which in turn increases calcium influx and affects mitochondrial structure and physiology. ROS production, mediated at least in part through mitochondrial alterations, trigger c-Abl signaling and lead to motoneuron death.

  2. Reactive oxygen species trigger motoneuron death in non-cell-autonomous models of ALS through activation of c-Abl signaling

    PubMed Central

    Rojas, Fabiola; Gonzalez, David; Cortes, Nicole; Ampuero, Estibaliz; Hernández, Diego E.; Fritz, Elsa; Abarzua, Sebastián; Martinez, Alexis; Elorza, Alvaro A.; Alvarez, Alejandra; Court, Felipe; van Zundert, Brigitte

    2015-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease in which pathogenesis and death of motor neurons are triggered by non-cell-autonomous mechanisms. We showed earlier that exposing primary rat spinal cord cultures to conditioned media derived from primary mouse astrocyte conditioned media (ACM) that express human SOD1G93A (ACM-hSOD1G93A) quickly enhances Nav channel-mediated excitability and calcium influx, generates intracellular reactive oxygen species (ROS), and leads to death of motoneurons within days. Here we examined the role of mitochondrial structure and physiology and of the activation of c-Abl, a tyrosine kinase that induces apoptosis. We show that ACM-hSOD1G93A, but not ACM-hSOD1WT, increases c-Abl activity in motoneurons, interneurons and glial cells, starting at 60 min; the c-Abl inhibitor STI571 (imatinib) prevents this ACM-hSOD1G93A-mediated motoneuron death. Interestingly, similar results were obtained with ACM derived from astrocytes expressing SOD1G86R or TDP43A315T. We further find that co-application of ACM-SOD1G93A with blockers of Nav channels (spermidine, mexiletine, or riluzole) or anti-oxidants (Trolox, esculetin, or tiron) effectively prevent c-Abl activation and motoneuron death. In addition, ACM-SOD1G93A induces alterations in the morphology of neuronal mitochondria that are related with their membrane depolarization. Finally, we find that blocking the opening of the mitochondrial permeability transition pore with cyclosporine A, or inhibiting mitochondrial calcium uptake with Ru360, reduces ROS production and c-Abl activation. Together, our data point to a sequence of events in which a toxic factor(s) released by ALS-expressing astrocytes rapidly induces hyper-excitability, which in turn increases calcium influx and affects mitochondrial structure and physiology. ROS production, mediated at least in part through mitochondrial alterations, trigger c-Abl signaling and lead to motoneuron death. PMID:26106294

  3. Mechanisms in photodynamic therapy: part two—cellular signaling, cell metabolism and modes of cell death

    PubMed Central

    Castano, Ana P.; Demidova, Tatiana N.; Hamblin, Michael R.

    2013-01-01

    Summary Photodynamic therapy (PDT) has been known for over a hundred years, but is only now becoming widely used. Originally developed as a tumor therapy, some of its most successful applications are for non-malignant disease. In the second of a series of three reviews, we will discuss the mechanisms that operate in PDT on a cellular level. In Part I [Castano AP, Demidova TN, Hamblin MR. Mechanism in photodynamic therapy: part one—photosensitizers, photochemistry and cellular localization. Photodiagn Photodyn Ther 2004;1:279–93] it was shown that one of the most important factors governing the outcome of PDT, is how the photosensitizer (PS) interacts with cells in the target tissue or tumor, and the key aspect of this interaction is the subcellular localization of the PS. PS can localize in mitochondria, lysosomes, endoplasmic reticulum, Golgi apparatus and plasma membranes. An explosion of investigation and explorations in the field of cell biology have elucidated many of the pathways that mammalian cells undergo when PS are delivered in tissue culture and subsequently illuminated. There is an acute stress response leading to changes in calcium and lipid metabolism and production of cytokines and stress proteins. Enzymes particularly, protein kinases, are activated and transcription factors are expressed. Many of the cellular responses are centered on mitochondria. These effects frequently lead to induction of apoptosis either by the mitochondrial pathway involving caspases and release of cytochrome c, or by pathways involving ceramide or death receptors. However, under certain circumstances cells subjected to PDT die by necrosis. Although there have been many reports of DNA damage caused by PDT, this is not thought to be an important cell-death pathway. This mechanistic research is expected to lead to optimization of PDT as a tumor treatment, and to rational selection of combination therapies that include PDT as a component. PMID:25048553

  4. Nanomaterial-Assisted Signal Enhancement of Hybridization for DNA Biosensors: A Review

    PubMed Central

    Liu, Jinhuai; Liu, Jinyun; Yang, Liangbao; Chen, Xing; Zhang, Meiyun; Meng, Fanli; Luo, Tao; Li, Minqiang

    2009-01-01

    Detection of DNA sequences has received broad attention due to its potential applications in a variety of fields. As sensitivity of DNA biosensors is determined by signal variation of hybridization events, the signal enhancement is of great significance for improving the sensitivity in DNA detection, which still remains a great challenge. Nanomaterials, which possess some unique chemical and physical properties caused by nanoscale effects, provide a new opportunity for developing novel nanomaterial-based signal-enhancers for DNA biosensors. In this review, recent progress concerning this field, including some newly-developed signal enhancement approaches using quantum-dots, carbon nanotubes and their composites reported by our group and other researchers are comprehensively summarized. Reports on signal enhancement of DNA biosensors by non-nanomaterials, such as enzymes and polymer reagents, are also reviewed for comparison. Furthermore, the prospects for developing DNA biosensors using nanomaterials as signal-enhancers in future are also indicated. PMID:22399999

  5. Oviductal estrogen receptor α signaling prevents protease-mediated embryo death

    PubMed Central

    Winuthayanon, Wipawee; Bernhardt, Miranda L; Padilla-Banks, Elizabeth; Myers, Page H; Edin, Matthew L; Lih, Fred B; Hewitt, Sylvia C; Korach, Kenneth S; Williams, Carmen J

    2015-01-01

    Development of uterine endometrial receptivity for implantation is orchestrated by cyclic steroid hormone-mediated signals. It is unknown if these signals are necessary for oviduct function in supporting fertilization and preimplantation development. Here we show that conditional knockout (cKO) mice lacking estrogen receptor α (ERα) in oviduct and uterine epithelial cells have impaired fertilization due to a dramatic reduction in sperm migration. In addition, all successfully fertilized eggs die before the 2-cell stage due to persistence of secreted innate immune mediators including proteases. Elevated protease activity in cKO oviducts causes premature degradation of the zona pellucida and embryo lysis, and wild-type embryos transferred into cKO oviducts fail to develop normally unless rescued by concomitant transfer of protease inhibitors. Thus, suppression of oviductal protease activity mediated by estrogen-epithelial ERα signaling is required for fertilization and preimplantation embryo development. These findings have implications for human infertility and post-coital contraception. DOI: http://dx.doi.org/10.7554/eLife.10453.001 PMID:26623518

  6. Targeting cell death signalling in cancer: minimising ‘Collateral damage'

    PubMed Central

    Fox, Joanna L; MacFarlane, Marion

    2016-01-01

    Targeting apoptosis for the treatment of cancer has become an increasingly attractive strategy, with agents in development to trigger extrinsic apoptosis via TRAIL signalling, or to prevent the anti-apoptotic activity of BCL-2 proteins or inhibitor of apoptosis (IAP) proteins. Although the evasion of apoptosis is one of the hallmarks of cancer, many cancers have intact apoptotic signalling pathways, which if unblocked could efficiently kill cancerous cells. However, it is becoming increasing clear that without a detailed understanding of both apoptotic and non-apoptotic signalling, and the key proteins that regulate these pathways, there can be dose-limiting toxicity and adverse effects associated with their modulation. Here we review the main apoptotic pathways directly targeted for anti-cancer therapy and the unforeseen consequences of their modulation. Furthermore, we highlight the importance of an in-depth mechanistic understanding of both the apoptotic and non-apoptotic functions of those proteins under investigation as anti-cancer drug targets and outline some novel approaches to sensitise cancer cells to apoptosis, thereby improving the efficacy of existing therapies when used in combination with novel targeted agents. PMID:27140313

  7. Xenopus death receptor-M1 and -M2, new members of the tumor necrosis factor receptor superfamily, trigger apoptotic signaling by differential mechanisms.

    PubMed

    Tamura, Kei; Noyama, Tomoko; Ishizawa, Yo-Hei; Takamatsu, Nobuhiko; Shiba, Tadayoshi; Ito, Michihiko

    2004-02-27

    Signaling through the tumor necrosis factor receptor (TNFR) superfamily can lead to apoptosis or promote cell survival, proliferation, and differentiation. A subset of this family, including TNFR1 and Fas, signals cell death via an intracellular death domain and therefore is termed the death receptor (DR) family. In this study, we identified new members of the DR family, designated xDR-M1 and xDR-M2, in Xenopus laevis. The two proteins, which show high homology (71.7% identity), have characteristics of the DR family, that is, three cysteine-rich domains, a transmembrane domain, and a death domain. To elucidate how members of xDR-M subfamily regulate cell death and survival, we examined the intracellular signaling mediated by these receptors in 293T and A6 cells. Overexpression of xDR-M2 induced apoptosis and activated caspase-8, c-Jun N-terminal kinase, and nuclear factor-kappaB, although its death domain to a greater extent than did that of xDR-M1 in 293T cells. A caspase-8 inhibitor potently blocked this apoptosis induced by xDR-M2. In contrast, xDR-M1 showed a greater ability to induce apoptosis through its death domain than did xDR-M2 in A6 cells. Interestingly, a general serine protease inhibitor, but not the caspase-8 inhibitor, blocked the xDR-M1-induced apoptosis. These results imply that activation of caspase-8 or serine protease(s) may be required for the xDR-M2- or xDR-M1-induced apoptosis, respectively. Although xDR-M1 and xDR-M2 are very similar to each other, the difference in their death domains may result in diverse signaling, suggesting distinct roles of xDR-M1 and xDR-M2 in cell death or survival.

  8. Smad1/Smad5 signaling in limb ectoderm functions redundantly and is required for interdigital programmed cell death.

    PubMed

    Wong, Yuk Lau; Behringer, Richard R; Kwan, Kin Ming

    2012-03-01

    Bone morphogenetic proteins (BMPs) are secreted signals that regulate apical ectodermal ridge (AER) functions and interdigital programmed cell death (PCD) of developing limb. However the identities of the intracellular mediators of these signals are unknown. To investigate the role of Smad proteins in BMP-regulated AER functions in limb development, we inactivated Smad1 and Smad5 selectively in AER and ventral ectoderm of developing limb, using Smad1 or/and Smad5 floxed alleles and an En1(Cre/+) knock-in allele. Single inactivation of either Smad1 or Smad5 did not result in limb abnormalities. However, the Smad1/Smad5 double mutants exhibited syndactyly due to a reduction in interdigital PCD and an increase in interdigital cell proliferation. Cell tracing experiments in the Smad1/Smad5 double mutants showed that ventral ectoderm became thicker and the descendents of ventral En1(Cre/+) expressing ectodermal cells were located at dorsal interdigital regions. At the molecular level, Fgf8 expression was prolonged in the interdigital ectoderm of embryonic day (E) 13 Smad1/Smad5 double mutants, suggesting that the ectopic Fgf8 expression may serve as a survival signal for interdigital epithelial and mesenchymal cells. Our result suggests that Smad1 and Smad5 are required and function redundantly as intracellular mediators for BMP signaling in the AER and ventral ectoderm. Smad1/Smad5 signaling in the AER and ventral ectoderm regulates interdigital tissue regression of developing limb. Our mutants with defects in interdigital PCD could also serve as a valuable model for investigation of PCD regulation machinery.

  9. The Inhibition of microRNA-128 on IGF-1-Activating mTOR Signaling Involves in Temozolomide-Induced Glioma Cell Apoptotic Death

    PubMed Central

    Chen, Peng-Hsu; Cheng, Chia-Hsiung; Shih, Chwen-Ming; Ho, Kuo-Hao; Lin, Cheng-Wei; Lee, Chin-Cheng; Liu, Ann-Jeng; Chang, Cheng-Kuei

    2016-01-01

    Temozolomide (TMZ), an alkylating agent of the imidazotetrazine series, is a first-line chemotherapeutic drug used in the clinical therapy of glioblastoma multiforme, the most common and high-grade primary glioma in adults. Micro (mi)RNAs, which are small noncoding RNAs, post-transcriptionally regulate gene expressions and are involved in gliomagenesis. However, no studies have reported relationships between TMZ and miRNA gene regulation. We investigated TMZ-mediated miRNA profiles and its molecular mechanisms underlying the induction of glioma cell death. By performing miRNA microarray and bioinformatics analyses, we observed that expression of 248 miRNAs was altered, including five significantly upregulated and 17 significantly downregulated miRNAs, in TMZ-treated U87MG cells. miR-128 expression levels were lower in different glioma cells and strongly associated with poor survival. TMZ treatment significantly upregulated miR-128 expression. TMZ significantly enhanced miR-128-1 promoter activity and transcriptionally regulated miR-128 levels through c-Jun N-terminal kinase 2/c-Jun pathways. The overexpression and knockdown of miR-128 expression significantly affected TMZ-mediated cell viability and apoptosis-related protein expression. Furthermore, the overexpression of miR-128 alone enhanced apoptotic death of glioma cells through caspase-3/9 activation, poly(ADP ribose) polymerase degradation, reactive oxygen species generation, mitochondrial membrane potential loss, and non-protective autophagy formation. Finally, we identified that key members in mammalian target of rapamycin (mTOR) signaling including mTOR, rapamycin-insensitive companion of mTOR, insulin-like growth factor 1, and PIK3R1, but not PDK1, were direct target genes of miR-128. TMZ inhibited mTOR signaling through miR-128 regulation. These results indicate that miR-128-inhibited mTOR signaling is involved in TMZ-mediated cytotoxicity. Our findings may provide a better understanding of cytotoxic

  10. Inhibition of autophagy enhances Hydroquinone-induced TK6 cell death.

    PubMed

    Xu, Longmei; Liu, Jiaxian; Chen, Yuting; Yun, Lin; Chen, Shaoyun; Zhou, Kairu; Lai, Bei; Song, Li; Yang, Hui; Liang, Hairong; Tang, Huanwen

    2017-03-02

    Hydroquinone (HQ), one of the metabolic products of benzene, is a carcinogen. It can induce apoptosis in lymphoma cells. However, whether HQ can induce autophagy and what roles autophagy plays in TK6 cells exposured to HQ remains unclear. In this study, we found that HQ could induce autophagy through techniques of qRT-PCR, Western blot, immunofluorescent assay of LC3 and transmission electron microscope. Furthermore, inhibiting autophagy using 3-methyladenine (3-MA) or chloroquine (CQ) significantly enhanced HQ-induced cell apoptosis, suggesting that autophagy may be a survival mechanism. Our study also showed that HQ activated PARP-1. Moreover, knockdown of PARP-1 strongly exhibited decreased autophagy related genes expression. In contrast, the absence of SIRT1 increased that. Altogether, our data provided evidence that HQ induced autophagy in TK6 cells and autophagy protected TK6 from HQ attack-induced injury in vitro, and the autophagy was partially mediated via activation of the PARP-1-SIRT1 signaling pathway.

  11. A magnetic switch for the control of cell death signalling in in vitro and in vivo systems

    NASA Astrophysics Data System (ADS)

    Cho, Mi Hyeon; Lee, Eun Jung; Son, Mina; Lee, Jae-Hyun; Yoo, Dongwon; Kim, Ji-Wook; Park, Seung Woo; Shin, Jeon-Soo; Cheon, Jinwoo

    2012-12-01

    The regulation of cellular activities in a controlled manner is one of the most challenging issues in fields ranging from cell biology to biomedicine. Nanoparticles have the potential of becoming useful tools for controlling cell signalling pathways in a space and time selective fashion. Here, we have developed magnetic nanoparticles that turn on apoptosis cell signalling by using a magnetic field in a remote and non-invasive manner. The magnetic switch consists of zinc-doped iron oxide magnetic nanoparticles (Zn0.4Fe2.6O4), conjugated with a targeting antibody for death receptor 4 (DR4) of DLD-1 colon cancer cells. The magnetic switch, in its On mode when a magnetic field is applied to aggregate magnetic nanoparticle-bound DR4s, promotes apoptosis signalling pathways. We have also demonstrated that the magnetic switch is operable at the micrometre scale and that it can be applied in an in vivo system where apoptotic morphological changes of zebrafish are successfully induced.

  12. The N-terminal loop of IRAK-4 death domain regulates ordered assembly of the Myddosome signalling scaffold

    PubMed Central

    Dossang, Anthony C. G.; Motshwene, Precious G.; Yang, Yang; Symmons, Martyn F.; Bryant, Clare E.; Borman, Satty; George, Julie; Weber, Alexander N. R.; Gay, Nicholas J.

    2016-01-01

    Activation of Toll-like receptors induces dimerization and the recruitment of the death domain (DD) adaptor protein MyD88 into an oligomeric post receptor complex termed the Myddosome. The Myddosome is a hub for inflammatory and oncogenic signaling and has a hierarchical arrangement with 6–8 MyD88 molecules assembling with exactly 4 of IRAK-4 and 4 of IRAK-2. Here we show that a conserved motif in IRAK-4 (Ser8-X-X-X-Arg12) is autophosphorylated and that the phosphorylated DD is unable to form Myddosomes. Furthermore a mutant DD with the phospho-mimetic residue Asp at this position is impaired in both signalling and Myddosome assembly. IRAK-4 Arg12 is also essential for Myddosome assembly and signalling and we propose that phosphorylated Ser8 induces the N-terminal loop to fold into an α-helix. This conformer is stabilised by an electrostatic interaction between phospho-Ser8 and Arg12 and would destabilise a critical interface between IRAK-4 and MyD88. Interestingly IRAK-2 does not conserve this motif and has an alternative interface in the Myddosome that requires Arg67, a residue conserved in paralogues, IRAK-1 and 3(M). PMID:27876844

  13. Deoxycholic acid modulates cell death signaling through changes in mitochondrial membrane properties[S

    PubMed Central

    Sousa, Tânia; Castro, Rui E.; Pinto, Sandra N.; Coutinho, Ana; Lucas, Susana D.; Moreira, Rui; Rodrigues, Cecília M. P.; Prieto, Manuel; Fernandes, Fábio

    2015-01-01

    Cytotoxic bile acids, such as deoxycholic acid (DCA), are responsible for hepatocyte cell death during intrahepatic cholestasis. The mechanisms responsible for this effect are unclear, and recent studies conflict, pointing to either a modulation of plasma membrane structure or mitochondrial-mediated toxicity through perturbation of mitochondrial outer membrane (MOM) properties. We conducted a comprehensive comparative study of the impact of cytotoxic and cytoprotective bile acids on the membrane structure of different cellular compartments. We show that DCA increases the plasma membrane fluidity of hepatocytes to a minor extent, and that this effect is not correlated with the incidence of apoptosis. Additionally, plasma membrane fluidity recovers to normal values over time suggesting the presence of cellular compensatory mechanisms for this perturbation. Colocalization experiments in living cells confirmed the presence of bile acids within mitochondrial membranes. Experiments with active isolated mitochondria revealed that physiologically active concentrations of DCA change MOM order in a concentration- and time-dependent manner, and that these changes preceded the mitochondrial permeability transition. Importantly, these effects are not observed on liposomes mimicking MOM lipid composition, suggesting that DCA apoptotic activity depends on features of mitochondrial membranes that are absent in protein-free mimetic liposomes, such as the double-membrane structure, lipid asymmetry, or mitochondrial protein environment. In contrast, the mechanism of action of cytoprotective bile acids is likely not associated with changes in cellular membrane structure. PMID:26351365

  14. Deoxycholic acid modulates cell death signaling through changes in mitochondrial membrane properties.

    PubMed

    Sousa, Tânia; Castro, Rui E; Pinto, Sandra N; Coutinho, Ana; Lucas, Susana D; Moreira, Rui; Rodrigues, Cecília M P; Prieto, Manuel; Fernandes, Fábio

    2015-11-01

    Cytotoxic bile acids, such as deoxycholic acid (DCA), are responsible for hepatocyte cell death during intrahepatic cholestasis. The mechanisms responsible for this effect are unclear, and recent studies conflict, pointing to either a modulation of plasma membrane structure or mitochondrial-mediated toxicity through perturbation of mitochondrial outer membrane (MOM) properties. We conducted a comprehensive comparative study of the impact of cytotoxic and cytoprotective bile acids on the membrane structure of different cellular compartments. We show that DCA increases the plasma membrane fluidity of hepatocytes to a minor extent, and that this effect is not correlated with the incidence of apoptosis. Additionally, plasma membrane fluidity recovers to normal values over time suggesting the presence of cellular compensatory mechanisms for this perturbation. Colocalization experiments in living cells confirmed the presence of bile acids within mitochondrial membranes. Experiments with active isolated mitochondria revealed that physiologically active concentrations of DCA change MOM order in a concentration- and time-dependent manner, and that these changes preceded the mitochondrial permeability transition. Importantly, these effects are not observed on liposomes mimicking MOM lipid composition, suggesting that DCA apoptotic activity depends on features of mitochondrial membranes that are absent in protein-free mimetic liposomes, such as the double-membrane structure, lipid asymmetry, or mitochondrial protein environment. In contrast, the mechanism of action of cytoprotective bile acids is likely not associated with changes in cellular membrane structure.

  15. Extrasynaptic NMDA receptor-induced tau overexpression mediates neuronal death through suppressing survival signaling ERK phosphorylation

    PubMed Central

    Sun, Xu-Ying; Tuo, Qing-Zhang; Liuyang, Zhen-Yu; Xie, Ao-Ji; Feng, Xiao-Long; Yan, Xiong; Qiu, Mei; Li, Shen; Wang, Xiu-Lian; Cao, Fu-Yuan; Wang, Xiao-Chuan; Wang, Jian-Zhi; Liu, Rong

    2016-01-01

    Intracellular accumulation of the hyperphosphorylated tau is a pathological hallmark in the brain of Alzheimer disease. Activation of extrasynaptic NMDA receptors (E-NMDARs) induces excitatory toxicity that is involved in Alzheimer's neurodegeneration. However, the intrinsic link between E-NMDARs and the tau-induced neuronal damage remains elusive. In the present study, we showed in cultured primary cortical neurons that activation of E-NMDA receptors but not synaptic NMDA receptors dramatically increased tau mRNA and protein levels, with a simultaneous neuronal degeneration and decreased neuronal survival. Memantine, a selective antagonist of E-NMDARs, reversed E-NMDARs-induced tau overexpression. Activation of E-NMDARs in wild-type mouse brains resulted in neuron loss in hippocampus, whereas tau deletion in neuronal cultures and in the mouse brains rescued the E-NMDARs-induced neuronal death and degeneration. The E-NMDARs-induced tau overexpression was correlated with a reduced ERK phosphorylation, whereas the increased MEK activity, decreased binding and activity of ERK phosphatase to ERK, and increased ERK phosphorylation were observed in tau knockout mice. On the contrary, addition of tau proteins promoted ERK dephosphorylation in vitro. Taking together, these results indicate that tau overexpression mediates the excitatory toxicity induced by E-NMDAR activation through inhibiting ERK phosphorylation. PMID:27809304

  16. [Death of neurons and glial cells, induced by a photodynamic injury: signaling processes and neurone-glial interactions].

    PubMed

    Uzdenskiĭ, A B; Kolosov, M S; Lobanov, A V

    2007-01-01

    The mechanisms of photodynamic (PD) injury of neurons and glial cells are reviewed. Neuron responses: firing stimulation at high photosensitizer concentrations and inhibition at low concentrations (< 10(-7) M) that were followed by necrosis, are described. Glial cells died from both necrosis and apoptosis. Local laser inactivation of a neuron enhanced PD-induced apoptosis of glial cells, thus indicating that neuron maintained the survival of glia. Inter- and intracellular signaling mediated photodamage of these cells. Using inhibitors or activators of signaling proteins, the involvement of Ca(2+)-, adenylate cyclase- and tyrosine kinase-mediated signaling pathways in responses of neurons and glial cells to photosensitization was shown. Their pharmacological modulation can change selectivity of PD injury of neuronal and glial cells and efficiency of PD therapy.

  17. Black Soybean Seed Coat Extract Prevents Hydrogen Peroxide-Mediated Cell Death via Extracellular Signal-Related Kinase Signalling in HepG2 Cells.

    PubMed

    Hashimoto, Naoto; Oki, Tomoyuki; Sasaki, Kazunori; Suda, Ikuo; Okuno, Shigenori

    2015-01-01

    Oxidative stress reduces cell viability and contributes to disease processes. Flavonoids including anthocyanins and proanthocyanidins reportedly induce intracellular antioxidant defence systems. Thus, in this study, we examined the antioxidant effects of a commercial extract from black soybean seed coats (BE), which are rich in anthocyanin and proanthocyanidin, and investigated the associated intracellular mechanisms in HepG2 cells. HepG2 cells treated with hydrogen peroxide (HPO) showed 60% viability, whereas pretreatment with BE-containing media for 2 h ameliorated HPO-mediated cell death by up to 90%. Pretreatment with BE for 2 h partially blocked HPO-mediated activation of ERK in HepG2 cells, and that for 1 h led to a 20% increase in intracellular total protein phosphatase (PP) activity, which is known to deactivate protein kinases. These results indicate that BE prevents HPO-mediated cell damage by inhibiting ERK signalling, potentially via PPs.

  18. Dual functions of gold nanorods as photothermal agent and autofluorescence enhancer to track cell death during plasmonic photothermal therapy.

    PubMed

    Kannadorai, Ravi Kumar; Chiew, Geraldine Giap Ying; Luo, Kathy Qian; Liu, Quan

    2015-02-01

    Gold nanorods have the potential to localize the treatment procedure by hyperthermia and influence the fluorescence. The longitudinal plasmon peak contributes to the photothermal effect by converting light to heat. When these nanorods are PEGylated, it not only makes it biocompatible but also acts as a spacer layer during fluorescence enhancement. When the PEGylated nanorods are internalized inside the cells through endocytosis, the transverse plasmonic peak combined with the enhanced absorption and scattering properties of the nanorods can enhance the autofluorescence emission intensity from the cell. The autofluorescence from the mitochondria inside cells which reflects the respiratory status of the cell was enhanced two times by the presence of nanorods within the cell. At four minutes, the nanorods incubated cells reached the hyperthermic temperature when illuminated continuously with near infrared laser. The cell viability test and autofluorescence intensity curve showed a similar trend indicating the progress of cell death over time. This is the first report to the best of our knowledge to suggest the potential of exploiting the dual capabilities of gold nanorods as photothermal agents and autofluorescence enhancer to track cell death.

  19. Danger signaling protein HMGB1 induces a distinct form of cell death accompanied by formation of giant mitochondria.

    PubMed

    Gdynia, Georg; Keith, Martina; Kopitz, Jürgen; Bergmann, Marion; Fassl, Anne; Weber, Alexander N R; George, Julie; Kees, Tim; Zentgraf, Hans-Walter; Wiestler, Otmar D; Schirmacher, Peter; Roth, Wilfried

    2010-11-01

    Cells dying by necrosis release the high-mobility group box 1 (HMGB1) protein, which has immunostimulatory effects. However, little is known about the direct actions of extracellular HMGB1 protein on cancer cells. Here, we show that recombinant human HMGB1 (rhHMGB1) exerts strong cytotoxic effects on malignant tumor cells. The rhHMGB1-induced cytotoxicity depends on the presence of mitochondria and leads to fast depletion of mitochondrial DNA, severe damage of the mitochondrial proteome by toxic malondialdehyde adducts, and formation of giant mitochondria. The formation of giant mitochondria is independent of direct nuclear signaling events, because giant mitochondria are also observed in cytoplasts lacking nuclei. Further, the reactive oxygen species scavenger N-acetylcysteine as well as c-Jun NH(2)-terminal kinase blockade inhibited the cytotoxic effect of rhHMGB1. Importantly, glioblastoma cells, but not normal astrocytes, were highly susceptible to rhHMGB1-induced cell death. Systemic treatment with rhHMGB1 results in significant growth inhibition of xenografted tumors in vivo. In summary, rhHMGB1 induces a distinct form of cell death in cancer cells, which differs from the known forms of apoptosis, autophagy, and senescence, possibly representing an important novel mechanism of specialized necrosis. Further, our findings suggest that rhHMGB1 may offer therapeutic applications in treatment of patients with malignant brain tumors.

  20. Gene profiling reveals hydrogen sulphide recruits death signaling via the N-methyl-D-aspartate receptor identifying commonalities with excitotoxicity.

    PubMed

    Chen, Minghui Jessica; Peng, Zhao Feng; Manikandan, Jayapal; Melendez, Alirio J; Tan, Gek San; Chung, Ching Ming; Li, Qiu-Tian; Tan, Theresa M; Deng, Lih Wen; Whiteman, Matthew; Beart, Philip M; Moore, Phillip K; Cheung, Nam Sang

    2011-05-01

    Recently the role of hydrogen sulphide (H(2) S) as a gasotransmitter stimulated wide interest owing to its involvement in Alzheimer's disease and ischemic stroke. Previously we demonstrated the importance of functional ionotropic glutamate receptors (GluRs) by neurons is critical for H(2) S-mediated dose- and time-dependent injury. Moreover N-methyl-D-aspartate receptor (NMDAR) antagonists abolished the consequences of H(2) S-induced neuronal death. This study focuses on deciphering the downstream effects activation of NMDAR on H(2) S-mediated neuronal injury by analyzing the time-course of global gene profiling (5, 15, and 24 h) to provide a comprehensive description of the recruitment of NMDAR-mediated signaling. Microarray analyses were performed on RNA from cultured mouse primary cortical neurons treated with 200 µM sodium hydrosulphide (NaHS) or NMDA over a time-course of 5-24 h. Data were validated via real-time PCR, western blotting, and global proteomic analysis. A substantial overlap of 1649 genes, accounting for over 80% of NMDA global gene profile present in that of H(2) S and over 50% vice versa, was observed. Within these commonly occurring genes, the percentage of transcriptional consistency at each time-point ranged from 81 to 97%. Gene families involved included those related to cell death, endoplasmic reticulum stress, calcium homeostasis, cell cycle, heat shock proteins, and chaperones. Examination of genes exclusive to H(2) S-mediated injury (43%) revealed extensive dysfunction of the ubiquitin-proteasome system. These data form a foundation for the development of screening platforms and define targets for intervention in H(2) S neuropathologies where NMDAR-activated signaling cascades played a substantial role.

  1. The canonical intrinsic mitochondrial death pathway has a non-apoptotic role in signaling lens cell differentiation.

    PubMed

    Weber, Gregory F; Menko, A Sue

    2005-06-10

    The mitochondrial cell death pathway is known for its role in signaling apoptosis. Here, we describe a novel function for the mitochondrial cell death pathway in signaling initiation of differentiation in the developing lens. Most remarkably, we induced lens cell differentiation by short-term exposure of lens epithelial cells to the apoptogen staurosporine. Activation of apoptosis-related pathways induced lens epithelial cells to express differentiation-specific markers and to undergo morphogenetic changes that led to formation of the lens-like structures known as lentoids. The fact that multiple stages of differentiation are expressed at a single stage of development in the embryonic lens made it possible to precisely determine the timing of expression of proteins associated with the apoptotic pathway. We discovered that there was high expression in the lens equatorial epithelium (the region of the lens in which differentiation is initiated) of pro-apoptotic molecules such as Bax and Bcl-x(S) and release of cytochrome c from mitochondria. Furthermore, we found significant caspase-3-like activity in the equatorial epithelium, yet this activity was far lower than that associated with lens cell apoptosis. These apoptotic pathways are likely regulated by the concurrent expression of prosurvival molecules, including Bcl-2 and Bcl-x(L); phosphorylation of Bad; and high expression of inhibitor of apoptosis proteins chicken IAP1, IAP3, and survivin. This finding suggests that prosurvival pathways allow pro-apoptotic molecules to function as molecular switches in the differentiation process without tipping the balance toward apoptosis. We call this process apoptosis-related Bcl-2- and caspase-dependent (ABC) differentiation.

  2. Adaptive phase matching probe-injection technique for enhancement of Brillouin scattering signal

    NASA Astrophysics Data System (ADS)

    Li, Hongwei; Shi, Guangyao; Lv, Yuelan; Zhang, Hongying; Gao, Wei

    2017-08-01

    We report on a simple and efficient method for enhancing Brillouin scattering signal, i.e., adaptive phase matching (APM) probe-injection technique. In this technique, a low-polarization broad-spectrum probe wave is injected opposite to the pump, which can enhance any stokes signal in its APM range instantly by selective stimulated Brillouin amplification. With advantages of simple scheme, real-time multi-signal enhancement and sweep-free measurement, this technique has a great potential for improving the signal-to-noise ratio of Brillouin gain spectrum in the Brillouin scattering application systems.

  3. Phytosphingosine in combination with ionizing radiation enhances apoptotic cell death in radiation-resistant cancer cells through ROS-dependent and -independent AIF release.

    PubMed

    Park, Moon-Taek; Kim, Min-Jung; Kang, Young-Hee; Choi, Soon-Young; Lee, Jae-Hoon; Choi, Jung-A; Kang, Chang-Mo; Cho, Chul-Koo; Kang, Seongman; Bae, Sangwoo; Lee, Yun-Sil; Chung, Hee Yong; Lee, Su-Jae

    2005-02-15

    The use of chemical modifiers as radiosensitizers in combination with low-dose irradiation may increase the therapeutic effect on cancer by overcoming a high apoptotic threshold. Here, we showed that phytosphingosine treatment in combination with gamma-radiation enhanced apoptotic cell death of radiation-resistant human T-cell lymphoma in a caspase-independent manner. Combination treatment induced an increase in intracellular reactive oxygen species (ROS) level, mitochondrial relocalization of B-cell lymphoma-2(Bcl-2)-associated X protein (Bax), poly-adenosine diphosphate (ADP)-ribose polymerase 1 (PARP-1) activation, and nuclear translocation of apoptosis-inducing factor (AIF). siRNA targeting of AIF effectively protected cells from the combination treatment-induced cell death. An antioxidant, N-acetyl-L-cysteine (NAC), inhibited Bax relocalization and AIF translocation but not PARP-1 activation. Moreover, transfection of Bax-siRNA significantly inhibited AIF translocation. Pretreatment of PARP-1 inhibitor, DPQ (3,4-dihydro-5-[4-(1-piperidinyl)-butoxy]-1(2H)-isoquinolinone), or PARP-1-siRNA also partially attenuated AIF translocation, whereas the same treatment did not affect intracellular ROS level and Bax redistribution. Taken together, these results demonstrate that enhancement of cell death of radiation-resistant cancer cells by phytosphingosine treatment in combination with gamma-radiation is mediated by nuclear translocation of AIF, which is in turn mediated both by ROS-dependent Bax relocalization and ROS-independent PARP-1 activation. The molecular signaling pathways that we elucidated in this study may provide potential drug targets for radiation sensitization of cancers refractive to radiation therapy.

  4. Enterococcus faecalis infection activates phosphatidylinositol 3-kinase signaling to block apoptotic cell death in macrophages.

    PubMed

    Zou, Jun; Shankar, Nathan

    2014-12-01

    Apoptosis is an intrinsic immune defense mechanism in the host response to microbial infection. Not surprisingly, many pathogens have evolved various strategies to manipulate this important pathway to benefit their own survival and dissemination in the host during infection. To our knowledge, no attempts have been made to explore the host cell survival signals modulated by the bacterium Enterococcus faecalis. Here, we show for the first time that during early stages of infection, internalized enterococci can prevent host cell (RAW264.7 cells, primary macrophages, and mouse embryonic fibroblasts [MEFs]) apoptosis induced by a wide spectrum of proapoptotic stimuli. Activation of caspase 3 and cleavage of the caspase 3 substrate poly(ADP-ribose) polymerase were inhibited in E. faecalis-infected cells, indicating that E. faecalis protects macrophages from apoptosis by inhibiting caspase 3 activation. This antiapoptotic activity in E. faecalis-infected cells was dependent on the activation of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway, which resulted in the increased expression of the antiapoptotic factor Bcl-2 and decreased expression of the proapoptotic factor Bax. Further analysis revealed that active E. faecalis physiology was important for inhibition of host cell apoptosis, and this feature seemed to be a strain-independent trait among E. faecalis isolates. Employing a mouse peritonitis model, we also determined that cells collected from the peritoneal lavage fluid of E. faecalis-infected mice showed reduced levels of apoptosis compared to cells from uninfected mice. These results show early modulation of apoptosis during infection and have important implications for enterococcal pathogenesis.

  5. A Method of Speech Periodicity Enhancement Using Transform-domain Signal Decomposition.

    PubMed

    Huang, Huang; Lee, Tan; Kleijn, W Bastiaan; Kong, Ying-Yee

    2015-03-01

    Periodicity is an important property of speech signals. It is the basis of the signal's fundamental frequency and the pitch of voice, which is crucial to speech communication. This paper presents a novel framework of periodicity enhancement for noisy speech. The enhancement is applied to the linear prediction residual of speech. The residual signal goes through a constant-pitch time warping process and two sequential lapped-frequency transforms, by which the periodic component is concentrated in certain transform coefficients. By emphasizing the respective transform coefficients, periodicity enhancement of noisy residual signal is achieved. The enhanced residual signal and estimated linear prediction filter parameters are used to synthesize the output speech. An adaptive algorithm is proposed for adjusting the weights for the periodic and aperiodic components. Effectiveness of the proposed approach is demonstrated via experimental evaluation. It is observed that harmonic structure of the original speech could be properly restored to improve the perceptual quality of enhanced speech.

  6. miR-134 regulates ischemia/reperfusion injury-induced neuronal cell death by regulating CREB signaling.

    PubMed

    Huang, Weidong; Liu, Xiaobin; Cao, Jie; Meng, Facai; Li, Min; Chen, Bo; Zhang, Jie

    2015-04-01

    microRNA-134 (miR-134) has been reported to be a brain-specific miRNA and is differently expressed in brain tissues subjected to ischemic injury. However, the underlying mechanism of miR-134 in regulating cerebral ischemic injury remains poorly understood. The current study was designed to delineate the molecular basis of miR-134 in regulating cerebral ischemic injury. Using the oxygen-glucose deprivation (OGD) model of hippocampal neuron ischemia in vitro, we found that the overexpression of miR-134 mediated by recombinant adeno-associated virus (AAV) vector infection significantly promoted neuron death induced by OGD/reoxygenation, whereas the inhibition of miR-134 provided protective effects against OGD/reoxygenation-induced cell death. Moreover, cyclic AMP (cAMP) response element-binding protein (CREB) as a putative target of miR-134 was downregulated and upregulated by miR-134 overexpression or inhibition, respectively. The direct interaction between miR-134 and the 3'-untranslated region (UTR) of CREB mRNA was further confirmed by dual-luciferase reporter assay. Overexpression of miR-134 also inhibited the expression of the downstream gene of CREB, including brain-derived neurotrophic factor (BDNF) and the anti-apoptotic gene Bcl-2, whereas the inhibition of miR-134 upregulated the expression of BDNF and Bcl-2 in neurons after OGD/reoxygenation. Notably, the knockdown of CREB by CREB siRNA apparently abrogated the protective effect of anti-miR-134 on OGD/reoxygenation-induced cell death. Taken together, our study suggests that downregulation of miR-134 alleviates ischemic injury through enhancing CREB expression and downstream genes, providing a promising and potential therapeutic target for cerebral ischemic injury.

  7. Involvement of NtERF3 in the cell death signalling pathway mediated by SIPK/WIPK and WRKY1 in tobacco plants.

    PubMed

    Ogata, T; Okada, H; Kawaide, H; Takahashi, H; Seo, S; Mitsuhara, I; Matsushita, Y

    2015-09-01

    We previously reported that one of the ethylene response factors (ERFs), NtERF3, and other members of the subgroup VIII-a ERFs of the AP2/ERF family exhibit cell death-inducing ability in tobacco leaves. In this study, we focused on the involvement of NtERF3 in a cell death signalling pathway in tobacco plants, particularly downstream of NtSIPK/NtWIPK and NtWRKY1, which are mitogen-activated protein kinases and a phosphorylation substrate of NtSIPK, respectively. An ERF-associated amphiphilic repression (EAR) motif-deficient NtERF3b mutant (NtERF3bΔEAR) that lacked cell death-inducing ability suppressed the induction of cell death caused by NtERF3a. The transient co-expression of NtERF3bΔEAR suppressed the hypersensitive reaction (HR)-like cell death induced by NtSIPK and NtWRKY1. The induction of cell death by NtSIPK and NtWRKY1 was also inhibited in transgenic plants expressing NtERF3bΔEAR. Analysis of gene expression, ethylene production and cell death symptoms in salicylic acid-deficient tobacco plants suggested the existence of some feedback regulation in the HR cell death signalling pathway mediated by SIPK/WIPK and WRKY1. Overall, these results suggest that NtERF3 functions downstream of NtSIPK/NtWIPK and NtWRKY1 in a cell death signalling pathway, with some feedback regulation.

  8. Nicotine-mediated signals modulate cell death and survival of T lymphocytes

    SciTech Connect

    Oloris, Silvia C.S.; Frazer-Abel, Ashley A.; Jubala, Cristan M.; Fosmire, Susan P.; Helm, Karen M.; Robinson, Sally R.; Korpela, Derek M.; Duckett, Megan M.; Baksh, Shairaz; Modiano, Jaime F.

    2010-02-01

    The capacity of nicotine to affect the behavior of non-neuronal cells through neuronal nicotinic acetylcholine receptors (nAChRs) has been the subject of considerable recent attention. Previously, we showed that exposure to nicotine activates the nuclear factor of activated T cells (NFAT) transcription factor in lymphocytes and endothelial cells, leading to alterations in cellular growth and vascular endothelial growth factor production. Here, we extend these studies to document effects of nicotine on lymphocyte survival. The data show that nicotine induces paradoxical effects that might alternatively enforce survival or trigger apoptosis, suggesting that depending on timing and context, nicotine might act both as a survival factor or as an inducer of apoptosis in normal or transformed lymphocytes, and possibly other non-neuronal cells. In addition, our results show that, while having overlapping functions, low and high affinity nAChRs also transmit signals that promote distinct outcomes in lymphocytes. The sum of our data suggests that selective modulation of nAChRs might be useful to regulate lymphocyte activation and survival in health and disease.

  9. Suppression of extracellular signal-related kinase and activation of p38 MAPK are two critical events leading to caspase-8- and mitochondria-mediated cell death in phytosphingosine-treated human cancer cells.

    PubMed

    Park, Moon-Taek; Choi, Jung-A; Kim, Min-Jeong; Um, Hong-Duck; Bae, Sangwoo; Kang, Chang-Mo; Cho, Chul-Koo; Kang, Seongman; Chung, Hee Yong; Lee, Yun-Sil; Lee, Su-Jae

    2003-12-12

    We previously demonstrated that the phytosphingosine-induced apoptosis was accompanied by the concomitant induction of both the caspase-8-mediated and mitochondrial activation-mediated apoptosis pathways. In the present study, we investigated the role of mitogen-activated protein kinases (MAPKs) in the activation of these two distinct cell death pathways induced by phytosphingosine in human cancer cells. Phytosphingosine caused strong induction of caspase-8 activity and caspase-independent Bax translocation to the mitochondria. A rapid decrease of phosphorylated ERK1/2 and a marked increase of p38 MAPK phosphorylation were observed within 10 min after phytosphingosine treatment. Activation of ERK1/2 by pretreatment with phorbol 12-myristate 13-acetate or forced expression of ERK1/2 attenuated phytosphingosine-induced caspase-8 activation. However, Bax translocation and caspase-9 activation was unaffected, indicating that down-regulation of the ERK activity is specifically required for the phytosphingosine-induced caspase-8-dependent cell death pathway. On the other hand, treatment with SB203580, a p38 MAPK-specific inhibitor, or expression of a dominant negative form of p38 MAPK suppressed phytosphingosine-induced translocation of the proapoptotic protein, Bax, from the cytosol to mitochondria, cytochrome c release, and subsequent caspase-9 activation but did not affect caspase-8 activation, indicating that activation of p38 MAPK is involved in the mitochondrial activation-mediated cell death pathway. Our results suggest that phytosphingosine can utilize two different MAPK signaling pathways for amplifying the apoptosis cascade, enhancing the understanding of the molecular mechanisms utilized by naturally occurring metabolites to regulate cell death. Molecular dissection of the signaling pathways that activate the apoptotic cell death machinery is critical for both our understanding of cell death events and development of cancer therapeutic agents.

  10. SCD1 negatively regulates autophagy-induced cell death in human hepatocellular carcinoma through inactivation of the AMPK signaling pathway.

    PubMed

    Huang, Guang-Ming; Jiang, Qing-Hu; Cai, Can; Qu, Mei; Shen, Wei

    2015-03-28

    Stearoyl-CoA desaturase 1 (SCD1) is a key regulator in the mechanisms of cell proliferation, survival and transformation to cancer, and autophagy also plays a critical role in hepatocellular carcinoma (HCC). However, whether SCD1 mediates autophagy in HCC remains unknown. In this study, we observed significantly elevated SCD1 expression levels and evident suppression of autophagy in HCC, and the positive SCD1 expression and autophagy defect were independently correlated with poor prognosis of HCC patients. We also found that the inhibition of SCD1 by a pharmacological inhibitor reduced cell viability and induced apoptosis and autophagy of human HCC cells in a dose- and time-dependent manner. Moreover, the pharmacological inhibition of AMPK supported the hypothesis that the induction of autophagy caused by SCD1 inhibition relied on AMPK stimulation. Furthermore, the human HCC cells death triggered by inhibition of SCD1 was partly involved in autophagy-induced apoptosis via AMPK signaling. Our findings reveal a novel role for SCD1 in the regulation of autophagy via AMPK signaling and provide mechanistic input for the clinical exploration that the combination of SCD1 inhibition with autophagy induction may be attractive for the management of HCC.

  11. Signal enhancement in collinear four-wave mixing

    SciTech Connect

    McKinstrie, C.J.; Luther, G.G.; Batha, S. )

    1990-03-01

    The solitary-wave solutions of the four-wave equations are studied, and their relevance to four-wave mixing in finite media is discussed. In general, the transfer of action from the pump waves to the probe and signal waves is limited by nonlinear phase shifts that detune the interaction. However, by controlling the linear phase mismatch judiciously, it is often possible to effect a complete transfer of action from the pump waves to the probe and signal waves.

  12. Multinuclear giant cell formation is enhanced by down-regulation of Wnt signaling in gastric cancer cell line, AGS

    SciTech Connect

    Kim, Shi-Mun; Kim, Rockki; Ryu, Jae-Hyun; Jho, Eek-Hoon; Song, Ki-Joon; Jang, Shyh-Ing; Kee, Sun-Ho . E-mail: keesh@korea.ac.kr

    2005-08-01

    AGS cells, which were derived from malignant gastric adenocarcinoma tissue, lack E-cadherin-mediated cell adhesion but have a high level of nuclear {beta}-catenin, which suggests altered Wnt signal. In addition, approximately 5% of AGS cells form multinuclear giant cells in the routine culture conditions, while taxol treatment causes most AGS cells to become giant cells. The observation of reduced nuclear {beta}-catenin levels in giant cells induced by taxol treatment prompted us to investigate the relationship between Wnt signaling and giant cell formation. After overnight serum starvation, the shape of AGS cells became flattened, and this morphological change was accompanied by decrease in Myc expression and an increase in the giant cell population. Lithium chloride treatment, which inhibits GSK3{beta} activity, reversed these serum starvation effects, which suggests an inverse relationship between Wnt signaling and giant cell formation. Furthermore, the down-regulation of Wnt signaling caused by the over-expression of ICAT, E-cadherin, and Axin enhanced giant cell formation. Therefore, down-regulation of Wnt signaling may be related to giant cell formation, which is considered to be a survival mechanism against induced cell death.

  13. Arctigenin enhances chemosensitivity of cancer cells to cisplatin through inhibition of the STAT3 signaling pathway.

    PubMed

    Yao, Xiangyang; Zhu, Fenfen; Zhao, Zhihui; Liu, Chang; Luo, Lan; Yin, Zhimin

    2011-10-01

    Arctigenin is a dibenzylbutyrolactone lignan isolated from Bardanae fructus, Arctium lappa L, Saussureamedusa, Torreya nucifera, and Ipomea cairica. It has been reported to exhibit anti-inflammatory activities, which is mainly mediated through its inhibitory effect on nuclear transcription factor-kappaB (NF-κB). But the role of arctigenin in JAK-STAT3 signaling pathways is still unclear. In present study, we investigated the effect of arctigenin on signal transducer and activator of transcription 3 (STAT3) pathway and evaluated whether suppression of STAT3 activity by arctigenin could sensitize cancer cells to a chemotherapeutic drug cisplatin. Our results show that arctigenin significantly suppressed both constitutively activated and IL-6-induced STAT3 phosphorylation and subsequent nuclear translocation in cancer cells. Inhibition of STAT3 tyrosine phosphorylation was found to be achieved through suppression of Src, JAK1, and JAK2, while suppression of STAT3 serine phosphorylation was mediated by inhibition of ERK activation. Pervanadate reversed the arctigenin-induced downregulation of STAT3 activation, suggesting the involvement of a protein tyrosine phosphatase. Indeed, arctigenin can obviously induce the expression of the PTP SHP-2. Furthermore, the constitutive activation level of STAT3 was found to be correlated to the resistance of cancer cells to cisplatin-induced apoptosis. Arctigenin dramatically promoted cisplatin-induced cell death in cancer cells, indicating that arctigenin enhanced the sensitivity of cancer cells to cisplatin mainly via STAT3 suppression. These observations suggest a novel anticancer function of arctigenin and a potential therapeutic strategy of using arctigenin in combination with chemotherapeutic agents for cancer treatment.

  14. Group IVA phospholipase A(2) deficiency prevents CCl4-induced hepatic cell death through the enhancement of autophagy.

    PubMed

    Ishihara, Keiichi; Kanai, Shiho; Tanaka, Kikuko; Kawashita, Eri; Akiba, Satoshi

    2016-02-26

    Group IVA phospholipase A2 (IVA-PLA2), which generates arachidonate, plays a role in inflammation. IVA-PLA2-deficiency reduced hepatotoxicity and hepatocyte cell death in mice that received a single dose of carbon tetrachloride (CCl4) without any inhibitory effects on CCl4-induced lipid peroxidation. An immunoblot analysis of extracts from wild-type mouse- and IVA-PLA2 KO mouse-derived primary hepatocytes that transiently expressed microtubule-associated protein 1 light chain 3B (LC3) revealed a higher amount of LC3-II, a typical index of autophagosome formation, in IVA-PLA2-deficient cells, suggesting the enhancement of constitutive autophagy. IVA-PLA2 may promote CCl4-induced cell death through the suppression of constitutive autophagy in hepatocytes.

  15. Matched filtering algorithm based on phase-shifting pursuit for ground-penetrating radar signal enhancement

    NASA Astrophysics Data System (ADS)

    Zhang, Hairu; Ouyang, Shan; Wang, Guofu; Wu, Suolu; Zhang, Faquan

    2014-01-01

    The received signals from ground-penetrating radar (GPR) contain round-trip echoes, clutters, and complex noise signals. These jamming signals seriously affect the interpretation precision of shallow geological subsurface information. In order to dissolve some useless signals in GPR signals, it is necessary to take appropriate measures to repress interference. Based on the electromagnetic field theory, the propagation characteristics of the transmitted GPR signal are analyzed. On this basis, a matched filtering algorithm based on phase-shifting pursuit is proposed to enhance the received GPR signals. At first, the intrinsic component libraries (ICL) can be generated by changing the phase of the transmitted GPR signal. Then, the correlation analysis between the local information of the received GPR signals extracted by sliding window method and each sample in ICL is studied to extract target echo signals. Experiments based on the GPR imaging demonstrate that the proposed algorithm could enhance the target echo signals to a certain extent. The integrated side lobe ratio of the imaging result of the enhanced GPR signals is 6.33 dB lower than the original ones. The resolution of target imaging can be improved.

  16. Amyloid-β induced astrocytosis and astrocyte death: Implication of FoxO3a-Bim-caspase3 death signaling.

    PubMed

    Saha, Pampa; Biswas, Subhas Chandra

    2015-09-01

    Astrocytes, the main element of the homeostatic system in the brain, are affected in various neurological conditions including Alzheimer's disease (AD). A common astrocytic reaction in pathological state is known as astrocytosis which is characterized by a specific change in astrocyte shape due to cytoskeletal remodeling, cytokine secretion and cellular proliferation. Astrocytes also undergo apoptosis in various neurological conditions or in response to toxic insults. AD is pathologically characterized by progressive deposition of amyloid-β (Aβ) in senile plaques, intraneuronal neurofibrillary tangles, synaptic dysfunction and neuron death. Astrocytosis and astrocyte death have been reported in AD brain as well as in response to Aβ in vitro. However, how astrocytes undergo both proliferation and death in response to Aβ remains elusive. In this study, we used primary cultures of cortical astrocytes and exposed them to various doses of oligomeric Aβ. We found that cultured astrocytes proliferate and manifest all signs of astrocytosis at a low dose of Aβ. However, at high dose of Aβ the activated astrocytes undergo apoptosis. Astrocytosis was also noticed in vivo in response to Aβ in the rat brain. Next, we investigated the mechanism of astrocyte apoptosis in response to a high dose of Aβ. We found that death of astrocyte induced by Aβ requires a set of molecules that are instrumental for neuron death in response to Aβ. It involves activation of Forkhead transcription factor Foxo3a, induction of its pro-apoptotic target Bim and activation of its downstream molecule, caspase3. Hence, this study demonstrates that the concentration of Aβ decides whether astrocytes do proliferate or undergo apoptosis via a mechanism that is required for neuron death.

  17. 5-Hydroxy-7-Methoxyflavone Triggers Mitochondrial-Associated Cell Death via Reactive Oxygen Species Signaling in Human Colon Carcinoma Cells

    PubMed Central

    Paul, Souren; Jakhar, Rekha; Han, Jaehong; Kang, Sun Chul

    2016-01-01

    Plant-derived compounds are an important source of clinically useful anti-cancer agents. Chrysin, a biologically active flavone found in many plants, has limited usage for cancer chemotherapeutics due to its poor oral bioavailability. 5-Hydroxy-7-methoxyflavone (HMF), an active natural chrysin derivative found in various plant sources, is known to modulate several biological activities. However, the mechanism underlying HMF-induced apoptotic cell death in human colorectal carcinoma cells in vitro is still unknown. Herein, HMF was shown to be capable of inducing cytotoxicity in HCT-116 cells and induced cell death in a dose-dependent manner. Treatment of HCT-116 cells with HMF caused DNA damage and triggered mitochondrial membrane perturbation accompanied by Cyt c release, down-regulation of Bcl-2, activation of BID and Bax, and caspase-3-mediated apoptosis. These results show that ROS generation by HMF was the crucial mediator behind ER stress induction, resulting in intracellular Ca2+ release, JNK phosphorylation, and activation of the mitochondrial apoptosis pathway. Furthermore, time course study also reveals that HMF treatment leads to increase in mitochondrial and cytosolic ROS generation and decrease in antioxidant enzymes expression. Temporal upregulation of IRE1-α expression and JNK phosphorylation was noticed after HMF treatment. These results were further confirmed by pre-treatment with the ROS scavenger N-acetyl-l-cysteine (NAC), which completely reversed the effects of HMF treatment by preventing lipid peroxidation, followed by abolishment of JNK phosphorylation and attenuation of apoptogenic marker proteins. These results emphasize that ROS generation by HMF treatment regulates the mitochondrial-mediated apoptotic signaling pathway in HCT-116 cells, demonstrating HMF as a promising pro-oxidant therapeutic candidate for targeting colorectal cancer. PMID:27116119

  18. Coordinate Autophagy and mTOR Pathway Inhibition Enhances Cell Death in Melanoma

    PubMed Central

    Xie, Xiaoqi; White, Eileen P.; Mehnert, Janice M.

    2013-01-01

    The phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway promotes melanoma tumor growth and survival while suppressing autophagy, a catabolic process through which cells collect and recycle cellular components to sustain energy homeostasis in starvation. Conversely, inhibitors of the PI3K/AKT/mTOR pathway, in particular the mTOR inhibitor temsirolimus (CCI-779), induce autophagy, which can promote tumor survival and thus, these agents potentially limit their own efficacy. We hypothesized that inhibition of autophagy in combination with mTOR inhibition would block this tumor survival mechanism and hence improve the cytotoxicity of mTOR inhibitors in melanoma. Here we found that melanoma cell lines of multiple genotypes exhibit high basal levels of autophagy. Knockdown of expression of the essential autophagy gene product ATG7 resulted in cell death, indicating that survival of melanoma cells is autophagy-dependent. We also found that the lysosomotropic agent and autophagy inhibitor hydroxychloroquine (HCQ) synergizes with CCI-779 and led to melanoma cell death via apoptosis. Combination treatment with CCI-779 and HCQ suppressed melanoma growth and induced cell death both in 3-dimensional (3D) spheroid cultures and in tumor xenografts. These data suggest that coordinate inhibition of the mTOR and autophagy pathways promotes apoptosis and could be a new therapeutic paradigm for the treatment of melanoma. PMID:23383069

  19. Enhancement of the Raman scattering signal due to a nanolens effect.

    PubMed

    Desmedt, A; Talaga, D; Bruneel, J L

    2007-06-01

    The Raman scattering signal of a substrate is investigated using a polystyrene nanolens of a few hundred nanometers inserted within the light path of a confocal microspectrometer. As observed in solid immersion microscopy, the nanolens is at the origin of the improvement of the spatial resolution. Furthermore, enhancement of the Raman scattering signal of the substrate is observed when measuring through the polystyrene bead. The enhancement factors have been measured for silicon, highly ordered pyrolytic graphite, and gallium arsenide substrates. This setup provides a new way of enhancing the Raman signal by means of a nanolens.

  20. A Novel Gene, OZONE-RESPONSIVE APOPLASTIC PROTEIN1, Enhances Cell Death in Ozone Stress in Rice1

    PubMed Central

    Ueda, Yoshiaki; Siddique, Shahid; Frei, Michael

    2015-01-01

    A novel protein, OZONE-RESPONSIVE APOPLASTIC PROTEIN1 (OsORAP1), was characterized, which was previously suggested as a candidate gene underlying OzT9, a quantitative trait locus for ozone stress tolerance in rice (Oryza sativa). The sequence of OsORAP1 was similar to that of ASCORBATE OXIDASE (AO) proteins. It was localized in the apoplast, as shown by transient expression of an OsORAP1/green fluorescent protein fusion construct in Nicotiana benthamiana leaf epidermal and mesophyll cells, but did not possess AO activity, as shown by heterologous expression of OsORAP1 in Arabidopsis (Arabidopsis thaliana) mutants with reduced background AO activity. A knockout rice line of OsORAP1 showed enhanced tolerance to ozone stress (120 nL L−1 average daytime concentration, 20 d), as demonstrated by less formation of leaf visible symptoms (i.e. cell death), less lipid peroxidation, and lower NADPH oxidase activity, indicating reduced active production of reactive oxygen species. In contrast, the effect of ozone on chlorophyll content was not significantly different among the lines. These observations suggested that OsORAP1 specifically induced cell death in ozone stress. Significantly enhanced expression of jasmonic acid-responsive genes in the knockout line implied the involvement of the jasmonic acid pathway in symptom mitigation. Sequence analysis revealed extensive polymorphisms in the promoter region of OsORAP1 between the ozone-susceptible cv Nipponbare and the ozone-tolerant cv Kasalath, the OzT9 donor variety, which could be responsible for the differential regulation of OsORAP1 reported earlier. These pieces of evidence suggested that OsORAP1 enhanced cell death in ozone stress, and its expression levels could explain the effect of a previously reported quantitative trait locus. PMID:26220952

  1. Enhanced BMP signaling results in supernumerary tooth formation in USAG-1 deficient mouse

    SciTech Connect

    Murashima-Suginami, Akiko; Takahashi, Katsu Sakata, Tomoko; Tsukamoto, Hiroko; Sugai, Manabu; Yanagita, Motoko; Shimizu, Akira; Sakurai, Takeshi; Slavkin, Harold C.; Bessho, Kazuhisa

    2008-05-16

    Uterine sensitization associated gene-1 (USAG-1) is a BMP antagonist, and also modulates Wnt signaling. We previously reported that USAG-1 deficient mice have supernumerary teeth. The supernumerary maxillary incisor appears to form as a result of the successive development of the rudimentary upper incisor. USAG-1 abrogation rescued apoptotic elimination of odontogenic mesenchymal cells. We confirmed that BMPs were expressed in both the epithelium and mesenchyme of the rudimentary incisor at E14 and E15. BMP signaling in the rudimentary maxillary incisor, assessed by expressions of Msx1 and Dlx2 and the phosphorylation of Smad protein, was significantly enhanced. Wnt signaling as demonstrated by the nuclear localization of {beta}-catenin was also up-regulated. Inhibition of BMP signaling rescues supernumerary tooth formation in E15 incisor explant culture. Based upon these results, we conclude that enhanced BMP signaling results in supernumerary teeth and BMP signaling was modulated by Wnt signaling in the USAG-1 deficient mouse model.

  2. N-glycosylation of mouse TRAIL-R and human TRAIL-R1 enhances TRAIL-induced death

    PubMed Central

    Dufour, Florent; Rattier, Thibault; Shirley, Sarah; Picarda, Gaelle; Constantinescu, Andrei Alexandru; Morlé, Aymeric; Zakaria, Al Batoul; Marcion, Guillaume; Causse, Sebastien; Szegezdi, Eva; Zajonc, Dirk Michael; Seigneuric, Renaud; Guichard, Gilles; Gharbi, Tijani; Picaud, Fabien; Herlem, Guillaume; Garrido, Carmen; Schneider, Pascal; Benedict, Chris Alan; Micheau, Olivier

    2017-01-01

    APO2L/TRAIL (TNF-related apoptosis-inducing ligand) induces death of tumor cells through two agonist receptors, TRAIL-R1 and TRAIL-R2. We demonstrate here that N-linked glycosylation (N-glyc) plays also an important regulatory role for TRAIL-R1-mediated and mouse TRAIL receptor (mTRAIL-R)-mediated apoptosis, but not for TRAIL-R2, which is devoid of N-glycans. Cells expressing N-glyc-defective mutants of TRAIL-R1 and mouse TRAIL-R were less sensitive to TRAIL than their wild-type counterparts. Defective apoptotic signaling by N-glyc-deficient TRAIL receptors was associated with lower TRAIL receptor aggregation and reduced DISC formation, but not with reduced TRAIL-binding affinity. Our results also indicate that TRAIL receptor N-glyc impacts immune evasion strategies. The cytomegalovirus (CMV) UL141 protein, which restricts cell-surface expression of human TRAIL death receptors, binds with significant higher affinity TRAIL-R1 lacking N-glyc, suggesting that this sugar modification may have evolved as a counterstrategy to prevent receptor inhibition by UL141. Altogether our findings demonstrate that N-glyc of TRAIL-R1 promotes TRAIL signaling and restricts virus-mediated inhibition. PMID:28186505

  3. 3',5-dihydroxy-3,4',7-trimethoxyflavone-induces ER-stress-associated HCT-116 programmed cell death via redox signaling.

    PubMed

    Singh, Mahendra Pal; Han, Jaehong; Kang, Sun Chul

    2017-04-01

    Quercetin, a well cognized bioactive flavone possessing great medicinal value, has limited usage. The rapid gastrointestinal digestion of quercetin is also a major obstacle for its clinical implementation due to low bioavailability and poor aqueous solubility. 3',5-dihydroxy-3,4',7-trimethoxyflavone (DTMF), a novel semi-synthetic derivative of quercetin, is known to modulate several biological activities. Therefore, in the present study we examined the cytotoxic mechanism of DTMF in concentration-dependent manner (25, 50, and 100μM; 24h) against HCT-116 human colon carcinoma cells. The cytotoxic potential of DTMF was characterized based on deformed cell morphology, increased ROS accumulation, loss of mitochondrial membrane potential (ΔѰm), increased mitochondrial mass, chromatin condensation, and typical DNA-fragmentation in HCT-116 cells. The results showed that DTMF-induced enhanced ROS production at higher concentration (100μM) as evidenced by upregulated expression of ER stress and apoptotic proteins with concomitant increase in PERK, CHOP, and JNK levels, when compared to N-acetyl cysteine (NAC, ROS inhibitor) treated HCT-116 cells, which depicts that DTMF might act as a crucial mediator of apoptosis signaling. Collectively, our results suggest that DTMF stimulates ROS-mediated oxidative stress, which in turn induces PERK-CHOP and JNK pathway of apoptosis to promote HCT-116 cell death.

  4. Joint Maximum Likelihood Time Delay Estimation of Unknown Event-Related Potential Signals for EEG Sensor Signal Quality Enhancement

    PubMed Central

    Kim, Kyungsoo; Lim, Sung-Ho; Lee, Jaeseok; Kang, Won-Seok; Moon, Cheil; Choi, Ji-Woong

    2016-01-01

    Electroencephalograms (EEGs) measure a brain signal that contains abundant information about the human brain function and health. For this reason, recent clinical brain research and brain computer interface (BCI) studies use EEG signals in many applications. Due to the significant noise in EEG traces, signal processing to enhance the signal to noise power ratio (SNR) is necessary for EEG analysis, especially for non-invasive EEG. A typical method to improve the SNR is averaging many trials of event related potential (ERP) signal that represents a brain’s response to a particular stimulus or a task. The averaging, however, is very sensitive to variable delays. In this study, we propose two time delay estimation (TDE) schemes based on a joint maximum likelihood (ML) criterion to compensate the uncertain delays which may be different in each trial. We evaluate the performance for different types of signals such as random, deterministic, and real EEG signals. The results show that the proposed schemes provide better performance than other conventional schemes employing averaged signal as a reference, e.g., up to 4 dB gain at the expected delay error of 10°. PMID:27322267

  5. Hyperthermia-enhanced TRAIL- and mapatumumab-induced apoptotic death is mediated through mitochondria in human colon cancer cells.

    PubMed

    Song, Xinxin; Kim, Han-Cheon; Kim, Seog-Young; Basse, Per; Park, Bae-Hang; Lee, Byeong-Chel; Lee, Yong J

    2012-05-01

    Colorectal cancer is the third leading cause of cancer-related mortality in the world; death usually results from uncontrolled metastatic disease. Previously, we developed a novel strategy of TNF-related apoptosis-inducing ligand (Apo2L/TRAIL) in combination with hyperthermia to treat hepatic colorectal metastases. However, previous studies suggest a potential hepatocyte cytotoxicity with TRAIL. Unlike TRAIL, anti-human TRAIL receptor antibody induces apoptosis without hepatocyte toxicity. In this study, we evaluated the anti-tumor efficacy of humanized anti-death receptor 4 (DR4) antibody mapatumumab (Mapa) by comparing it with TRAIL in combination with hyperthermia. TRAIL, which binds to both DR4 and death receptor 5 (DR5), was approximately tenfold more effective than Mapa in inducing apoptosis. However, hyperthermia enhances apoptosis induced by either agent. We observed that the synergistic effect was mediated through elevation of reactive oxygen species, c-Jun N-terminal kinase activation, Bax oligomerization, and translocalization to the mitochondria, loss of mitochondrial membrane potential, release of cytochrome c to cytosol, activation of caspases, and increase in poly(ADP-ribose) polymerase cleavage. We believe that the successful outcome of this study will support the application of Mapa in combination with hyperthermia to colorectal hepatic metastases.

  6. Library Synthesis, Screening, and Discovery of Modified Zinc(II)-Bis(dipicolylamine) Probe for Enhanced Molecular Imaging of Cell Death

    PubMed Central

    2015-01-01

    Zinc(II)-bis(dipicolylamine) (Zn-BDPA) coordination complexes selectively target the surfaces of dead and dying mammalian cells, and they have promise as molecular probes for imaging cell death. A necessary step toward eventual clinical imaging applications is the development of next-generation Zn-BDPA complexes with enhanced affinity for the cell death membrane biomarker, phosphatidylserine (PS). This study employed an iterative cycle of library synthesis and screening, using a novel rapid equilibrium dialysis assay, to discover a modified Zn-BDPA structure with high and selective affinity for vesicles containing PS. The lead structure was converted into a deep-red fluorescent probe and its targeting and imaging performance was compared with an unmodified control Zn-BDPA probe. The evaluation process included a series of FRET-based vesicle titration studies, cell microscopy experiments, and rat tumor biodistribution measurements. In all cases, the modified probe exhibited comparatively higher affinity and selectivity for the target membranes of dead and dying cells. The results show that this next-generation deep-red fluorescent Zn-BDPA probe is well suited for preclinical molecular imaging of cell death in cell cultures and animal models. Furthermore, it should be possible to substitute the deep-red fluorophore with alternative reporter groups that enable clinically useful, deep-tissue imaging modalities, such as MRI and nuclear imaging. PMID:24575875

  7. A p38MAPK/MK2 signaling pathway leading to redox stress, cell death and ischemia/reperfusion injury

    PubMed Central

    2014-01-01

    Background Many diseases and pathological conditions are characterized by transient or constitutive overproduction of reactive oxygen species (ROS). ROS are causal for ischemia/reperfusion (IR)-associated tissue injury (IRI), a major contributor to organ dysfunction or failure. Preventing IRI with antioxidants failed in the clinic, most likely due to the difficulty to timely and efficiently target them to the site of ROS production and action. IR is also characterized by changes in the activity of intracellular signaling molecules including the stress kinase p38MAPK. While ROS can cause the activation of p38MAPK, we recently obtained in vitro evidence that p38MAPK activation is responsible for elevated mitochondrial ROS levels, thus suggesting a role for p38MAPK upstream of ROS and their damaging effects. Results Here we identified p38MAPKα as the predominantly expressed isoform in HL-1 cardiomyocytes and siRNA-mediated knockdown demonstrated the pro-oxidant role of p38MAPKα signaling. Moreover, the knockout of the p38MAPK effector MAPKAP kinase 2 (MK2) reproduced the effect of inhibiting or knocking down p38MAPK. To translate these findings into a setting closer to the clinic a stringent kidney clamping model was used. p38MAPK activity increased upon reperfusion and p38MAPK inhibition by the inhibitor BIRB796 almost completely prevented severe functional impairment caused by IR. Histological and molecular analyses showed that protection resulted from decreased redox stress and apoptotic cell death. Conclusions These data highlight a novel and important mechanism for p38MAPK to cause IRI and suggest it as a potential therapeutic target for prevention of tissue injury. PMID:24423080

  8. Signal enhancement and suppression during visual-spatial selective attention.

    PubMed

    Couperus, J W; Mangun, G R

    2010-11-04

    Selective attention involves the relative enhancement of relevant versus irrelevant stimuli. However, whether this relative enhancement involves primarily enhancement of attended stimuli, or suppression of irrelevant stimuli, remains controversial. Moreover, if both enhancement and suppression are involved, whether they result from a single mechanism or separate mechanisms during attentional control or selection is not known. In two experiments using a spatial cuing paradigm with task-relevant targets and irrelevant distractors, target, and distractor processing was examined as a function of distractor expectancy. Additionally, in the second study the interaction of perceptual load and distractor expectancy was explored. In both experiments, distractors were either validly cued (70%) or invalidly cued (30%) in order to examine the effects of distractor expectancy on attentional control as well as target and distractor processing. The effects of distractor expectancy were assessed using event-related potentials recorded during the cue-to-target period (preparatory attention) and in response to the task-relevant target stimuli (selective stimulus processing). Analyses of distractor-present displays (anticipated versus unanticipated), showed modulations in brain activity during both the preparatory period and during target processing. The pattern of brain responses suggest both facilitation of attended targets and suppression of unattended distractors. These findings provide evidence for a two-process model of visual-spatial selective attention, where one mechanism (facilitation) influences relevant stimuli and another (suppression) acts to filter distracting stimuli.

  9. LISA Framework for Enhancing Gravitational Wave Signal Extraction Techniques

    NASA Technical Reports Server (NTRS)

    Thompson, David E.; Thirumalainambi, Rajkumar

    2006-01-01

    This paper describes the development of a Framework for benchmarking and comparing signal-extraction and noise-interference-removal methods that are applicable to interferometric Gravitational Wave detector systems. The primary use is towards comparing signal and noise extraction techniques at LISA frequencies from multiple (possibly confused) ,gravitational wave sources. The Framework includes extensive hybrid learning/classification algorithms, as well as post-processing regularization methods, and is based on a unique plug-and-play (component) architecture. Published methods for signal extraction and interference removal at LISA Frequencies are being encoded, as well as multiple source noise models, so that the stiffness of GW Sensitivity Space can be explored under each combination of methods. Furthermore, synthetic datasets and source models can be created and imported into the Framework, and specific degraded numerical experiments can be run to test the flexibility of the analysis methods. The Framework also supports use of full current LISA Testbeds, Synthetic data systems, and Simulators already in existence through plug-ins and wrappers, thus preserving those legacy codes and systems in tact. Because of the component-based architecture, all selected procedures can be registered or de-registered at run-time, and are completely reusable, reconfigurable, and modular.

  10. Up-regulation of FLIP in cisplatin-selected HeLa cells causes cross-resistance to CD95/Fas death signalling.

    PubMed Central

    Kamarajan, Pachiyappan; Sun, Nian-Kang; Chao, Chuck C-K

    2003-01-01

    Cisplatin-selected cervix carcinoma HeLa cell lines induced less apoptosis, and weaker activation by cisplatin or Fas-activating antibody, of mitochondrial-associated caspase-9 and death receptor-mediated caspase-8 than did parental cells. Furthermore, less DISC (death-inducing signalling complex) was formed in cisplatin-selected cell lines than in parental cells. Ac-IETD-CHO (acetyl-Ile-Glu-Thr-Asp-aldehyde), which has a certain preference for inhibiting caspase-8, or Fas-antagonistic antibody, significantly inhibited cisplatin-induced apoptosis in both parental and cisplatin-selected HeLa cell lines. These results imply that cell-surface death signalling is inducible by cisplatin; that reduction of this pathway is associated with drug resistance, and that cisplatin-selected cells acquire cross-resistance to cell-surface death signalling. Sequential up-regulation of FLIP (FLICE-like inhibitory protein), but not Bcl-2, Bcl-x(L) or inhibitors of apoptosis protein (IAPs), was observed in resistant cells but not in parental cells. The inhibition of FLIP by FLIP antisense oligonucleotides promotes cisplatin and Fas-antibody-induced apoptosis. However, the modulation of apoptosis by FLIP antisense oligonucleotides in resistant cells is greater than that in parental cells. The presented data reveal that the up-regulation of FLIP may contribute to the suppression of apoptosis and thereby change cells that are resistant to cisplatin and Fas-mediated death signals. The results also show that cancer cells that have undergone long-term chemotherapy and become chemoresistant may change the FLIP level, becoming cross-resistant to death factors such as Fas. PMID:12911332

  11. Hypoxia-inducible factor 1/heme oxygenase 1 cascade as upstream signals in the prolife role of heat shock protein 70 at rostral ventrolateral medulla during experimental brain stem death.

    PubMed

    Chang, Alice Y W; Chan, Julie Y H; Cheng, Hsiao-Lei; Tsai, Ching-Yi; Chan, Samuel H H

    2009-12-01

    As the origin of a life-and-death signal that reflects central cardiovascular regulatory failure during brain stem death, the rostral ventrolateral medulla (RVLM) is a suitable neural substrate to delineate the cellular mechanisms of this fateful phenomenon. Based on a clinically relevant animal model that used the organophosphate pesticide mevinphos (Mev) as the experimental insult, we reported previously that heat shock protein 70 (HSP70) in RVLM plays a prolife role by ameliorating circulatory depression during brain stem death. Because Mev also elicits significant hypoxia in RVLM, this study evaluated the hypothesis that the hypoxia-inducible factor 1 (HIF-1)/heme oxygenase 1 (HO-1) cascade acts as upstream signals in the prolife role of HSP70 at RVLM during experimental brain stem death. In Sprague-Dawley rats maintained under propofol anesthesia, transcription activity assay or Western blot analysis revealed an enhancement of nuclear activity of HIF-1alpha or augmentation of HO-1 and HSP70 expression in RVLM preferentially during the prolife phase of Mev intoxication. Loss-of-function manipulations in RVLM using HIF-1alpha, HIF-1beta, or HO-1 antiserum or antisense hif-1alpha or ho-1 oligonucleotide significantly antagonized the preferential upregulation of HSP70, depressed the sustained cardiovascular regulatory machinery during the prolife phase, and exacerbated circulatory depression during the prodeath phase. Immunoneutralization of HIF-1alpha also blunted the preferential increase in HO-1 expression. We conclude that the repertoire of cellular events in RVLM during the prolife phase in our Mev intoxication of brain stem death triggered by hypoxia entails sequential activation of HIF-1, HO-1, and HSP70, leading to neuroprotection by amelioration of cardiovascular depression.

  12. Identification of novel binding partners (annexins) for the cell death signal phosphatidylserine and definition of their recognition motif.

    PubMed

    Rosenbaum, Sabrina; Kreft, Sandra; Etich, Julia; Frie, Christian; Stermann, Jacek; Grskovic, Ivan; Frey, Benjamin; Mielenz, Dirk; Pöschl, Ernst; Gaipl, Udo; Paulsson, Mats; Brachvogel, Bent

    2011-02-18

    Identification and clearance of apoptotic cells prevents the release of harmful cell contents thereby suppressing inflammation and autoimmune reactions. Highly conserved annexins may modulate the phagocytic cell removal by acting as bridging molecules to phosphatidylserine, a characteristic phagocytosis signal of dying cells. In this study five members of the structurally and functionally related annexin family were characterized for their capacity to interact with phosphatidylserine and dying cells. The results showed that AnxA3, AnxA4, AnxA13, and the already described interaction partner AnxA5 can bind to phosphatidylserine and apoptotic cells, whereas AnxA8 lacks this ability. Sequence alignment experiments located the essential amino residues for the recognition of surface exposed phosphatidylserine within the calcium binding motifs common to all annexins. These amino acid residues were missing in the evolutionary young AnxA8 and when they were reintroduced by site directed mutagenesis AnxA8 gains the capability to interact with phosphatidylserine containing liposomes and apoptotic cells. By defining the evolutionary conserved amino acid residues mediating phosphatidylserine binding of annexins we show that the recognition of dying cells represent a common feature of most annexins. Hence, the individual annexin repertoire bound to the cell surface of dying cells may fulfil opsonin-like function in cell death recognition.

  13. Vorinostat-induced autophagy switches from a death-promoting to a cytoprotective signal to drive acquired resistance.

    PubMed

    Dupéré-Richer, D; Kinal, M; Ménasché, V; Nielsen, T H; Del Rincon, S; Pettersson, F; Miller, W H

    2013-02-07

    Histone deacetylase inhibitors (HDACi) have shown promising activity against hematological malignancies in clinical trials and have led to the approval of vorinostat for the treatment of cutaneous T-cell lymphoma. However, de novo or acquired resistance to HDACi therapy is inevitable, and their molecular mechanisms are still unclear. To gain insight into HDACi resistance, we developed vorinostat-resistant clones from the hematological cell lines U937 and SUDHL6. Although cross-resistant to some but not all HDACi, the resistant cell lines exhibit dramatically increased sensitivity toward chloroquine, an inhibitor of autophagy. Consistent with this, resistant cells growing in vorinostat show increased autophagy. Inhibition of autophagy in vorinostat-resistant U937 cells by knockdown of Beclin-1 or Lamp-2 (lysosome-associated membrane protein 2) restores sensitivity to vorinostat. Interestingly, autophagy is also activated in parental U937 cells by de novo treatment with vorinostat. However, in contrast to the resistant cells, inhibition of autophagy decreases sensitivity to vorinostat. These results indicate that autophagy can switch from a proapoptotic signal to a prosurvival function driving acquired resistance. Moreover, inducers of autophagy (such as mammalian target of rapamycin inhibitors) synergize with vorinostat to induce cell death in parental cells, whereas the resistant cells remain insensitive. These data highlight the complexity of the design of combination strategies using modulators of autophagy and HDACi for the treatment of hematological malignancies.

  14. Downregulation of renal tubular Wnt/β-catenin signaling by Dickkopf-3 induces tubular cell death in proteinuric nephropathy

    PubMed Central

    Wong, D W L; Yiu, W H; Wu, H J; Li, R X; Liu, Y; Chan, K W; Leung, J C K; Chan, L Y Y; Lai, K N; Tang, S C W

    2016-01-01

    Studies on the role of Wnt/β-catenin signaling in different forms of kidney disease have yielded discrepant results. Here, we report the biphasic change of renal β-catenin expression in mice with overload proteinuria in which β-catenin was upregulated at the early stage (4 weeks after disease induction) but abrogated at the late phase (8 weeks). Acute albuminuria was observed at 1 week after bovine serum albumin injection, followed by partial remission at 4 weeks that coincided with overexpression of renal tubular β-catenin. Interestingly, a rebound in albuminuria at 8 weeks was accompanied by downregulated tubular β-catenin expression and heightened tubular apoptosis. In addition, there was an inverse relationship between Dickkopf-3 (Dkk-3) and renal tubular β-catenin expression at these time points. In vitro, a similar trend in β-catenin expression was observed in human kidney-2 (HK-2) cells with acute (upregulation) and prolonged (downregulation) exposure to albumin. Induction of a proapoptotic phenotype by albumin was significantly enhanced by silencing β-catenin in HK-2 cells. Finally, Dkk-3 expression and secretion was increased after prolonged exposure to albumin, leading to the suppression of intracellular β-catenin signaling pathway. The effect of Dkk-3 on β-catenin signaling was confirmed by incubation with exogenous Dkk-3 in HK-2 cells. Taken together, these data suggest that downregulation of tubular β-catenin signaling induced by Dkk-3 has a detrimental role in chronic proteinuria, partially through the increase in apoptosis. PMID:27010856

  15. Enhancement of Signal to Noise Ratio Using Bispectrum. A Quantitative Analysis for Very Low SNR

    DTIC Science & Technology

    2001-10-25

    Enhancement of Signal to Noise Ratio Using Bispectrum A Quantitative Analysis for Very Low SNR Payam Yeganeh, Mohammad H. Moradi, Ali Reshad...Dept. of Biomedical Engineering, AMIR KABIR University of Technology Abstract- Bispectrum has been widely used to enhance the SNR . This is based...consider the use of Bispectrum techniques when repeated measurements are made of a deterministic signal embedded in random noise where SNR is in the

  16. Dexamethasone enhances serum deprivation-induced necrotic death of rat C6 glioma cells through activation of glucocorticoid receptors.

    PubMed

    Morita, K; Ishimura, K; Tsuruo, Y; Wong, D L

    1999-01-23

    Glucocorticoids have been shown to be neurotoxic and appear to play a role in neuronal cell loss during aging and following neuropathological insults. However, very little is known about the effects of these steroid hormones on glial cells. The effect of the synthetic glucocorticoid dexamethasone (DEX) on glial cell viability was therefore examined by measuring neutral red uptake into rat C6 glioma cells. Serum deprivation markedly reduced cell viability, and this effect was significantly enhanced by DEX. Electrophoretic analysis showed that the cell damage induced by either serum deprivation alone or in combination with DEX was not accompanied by the degradation of DNA into nucleosomic fragments. Electron microscopic studies confirmed that serum deprivation and glucocorticoid treatment caused necrotic cell death. Furthermore, the effect of DEX on cell viability could be mimicked by the glucocorticoid receptor agonist RU28362, and completely prevented by the glucocorticoid receptor antagonist RU38486. These results indicate that dexamethasone can enhance the necrotic death of glioma cells induced by serum deprivation, suggesting that glucocorticoids may be involved in the chronic alteration of brain function arising from neuropathological damage to glial cells.

  17. Oxygen in human health from life to death--An approach to teaching redox biology and signaling to graduate and medical students.

    PubMed

    Briehl, Margaret M

    2015-08-01

    In the absence of oxygen human life is measured in minutes. In the presence of oxygen, normal metabolism generates reactive species (ROS) that have the potential to cause cell injury contributing to human aging and disease. Between these extremes, organisms have developed means for sensing oxygen and ROS and regulating their cellular processes in response. Redox signaling contributes to the control of cell proliferation and death. Aberrant redox signaling underlies many human diseases. The attributes acquired by altered redox homeostasis in cancer cells illustrate this particularly well. This teaching review and the accompanying illustrations provide an introduction to redox biology and signaling aimed at instructors of graduate and medical students.

  18. Enhancement of MS Signal Processing For Improved Cancer Biomarker Discovery

    NASA Astrophysics Data System (ADS)

    Si, Qian

    Technological advances in proteomics have shown great potential in detecting cancer at the earliest stages. One way is to use the time of flight mass spectroscopy to identify biomarkers, or early disease indicators related to the cancer. Pattern analysis of time of flight mass spectra data from blood and tissue samples gives great hope for the identification of potential biomarkers among the complex mixture of biological and chemical samples for the early cancer detection. One of the keys issues is the pre-processing of raw mass spectra data. A lot of challenges need to be addressed: unknown noise character associated with the large volume of data, high variability in the mass spectroscopy measurements, and poorly understood signal background and so on. This dissertation focuses on developing statistical algorithms and creating data mining tools for computationally improved signal processing for mass spectrometry data. I have introduced an advanced accurate estimate of the noise model and a half-supervised method of mass spectrum data processing which requires little knowledge about the data.

  19. PEGylation of a Maltose Biosensor Promotes Enhanced Signal Response

    SciTech Connect

    Dattelbaum, Andrew; Baker, Gary A; Fox, John M; Iyer, Srinivas; Dattelbaum, Jonathan

    2009-01-01

    A robust method to immobilize a maltose biosensor is described using an engineered maltose periplasmic binding protein (PBP) covalently coupled to NBDamide, an environmentally sensitive fluorophore. A mesoporous silica sol-gel derived from diglycerylsilane (DGS) was constructed to embed the maltose biosensor, and the ligand reporting fluorescence properties were meas red. When sequestered in the DGS-derived silica matrix, the biosensor retained maltose-dependent fluorescence sensing capability with micromolar affinity, which is consistent with the protein free in solution. The MBP-NBD conjugate was further modified by covalent conjugation with poly(ethylene glycol)-5000 (PEG) to promote the retention of water molecules around the protein and to reduce possible steric effects between the silica matrix and protein. Bioconjugation with PEG molecules does not significantly affect the signaling response of the protein in solution. When immobilized in the DGS polymer, a consistent increase in fluorescence intensity was observed as compared to the protein not functionalized with PEG. To our knowledge, this report presents the first successful method to embed a PBP biosensor in a polymerized matrix and retain signaling response using an environmentally sensitive probe. The immobilization method presented here should be easily adaptable to all conformation-dependent biosensors.

  20. HnRNP-L mediates bladder cancer progression by inhibiting apoptotic signaling and enhancing MAPK signaling pathways.

    PubMed

    Lv, Daojun; Wu, Huayan; Xing, Rongwei; Shu, Fangpeng; Lei, Bin; Lei, Chengyong; Zhou, Xumin; Wan, Bo; Yang, Yu; Zhong, Liren; Mao, Xiangming; Zou, Yaguang

    2017-01-11

    Heterogeneous nuclear ribonucleoprotein L (hnRNP-L) is a promoter of various kinds of cancers, but its actions in bladder cancer (BC) are unclear. In this study, we investigated the function and the underlying mechanism of hnRNP-L in bladder carcinogenesis. Our results demonstrated that enhanced hnRNP-L expression in BC tissues was associated with poor overall survival of BC patients. Depletion of hnRNP-L significantly suppressed cell proliferation in vitro and inhibited xenograft tumor growth in vivo. Furthermore, downregulation of hnRNP-L resulted in G1-phase cell cycle arrest and enhanced apoptosis accompanied by inhibition of EMT and cell migration. All these cellular changes were reversed by ectopic expression of hnRNP-L. Deletion of hnRNP-L resulted in decreased expression of Bcl-2, enhanced expression of caspases-3, -6 and -9 and inhibition of the MAPK signaling pathway. These findings demonstrate that hnRNP-L contributes to poor prognosis and tumor progression of BC by inhibiting the intrinsic apoptotic signaling and enhancing MAPK signaling pathways.

  1. Autophagy negatively regulates cell death by controlling NPR1-dependent salicylic acid signaling during senescence and the innate immune response in Arabidopsis.

    PubMed

    Yoshimoto, Kohki; Jikumaru, Yusuke; Kamiya, Yuji; Kusano, Miyako; Consonni, Chiara; Panstruga, Ralph; Ohsumi, Yoshinori; Shirasu, Ken

    2009-09-01

    Autophagy is an evolutionarily conserved intracellular process for vacuolar degradation of cytoplasmic components. In higher plants, autophagy defects result in early senescence and excessive immunity-related programmed cell death (PCD) irrespective of nutrient conditions; however, the mechanisms by which cells die in the absence of autophagy have been unclear. Here, we demonstrate a conserved requirement for salicylic acid (SA) signaling for these phenomena in autophagy-defective mutants (atg mutants). The atg mutant phenotypes of accelerated PCD in senescence and immunity are SA signaling dependent but do not require intact jasmonic acid or ethylene signaling pathways. Application of an SA agonist induces the senescence/cell death phenotype in SA-deficient atg mutants but not in atg npr1 plants, suggesting that the cell death phenotypes in the atg mutants are dependent on the SA signal transducer NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1. We also show that autophagy is induced by the SA agonist. These findings imply that plant autophagy operates a novel negative feedback loop modulating SA signaling to negatively regulate senescence and immunity-related PCD.

  2. ASIC channel inhibition enhances excitotoxic neuronal death in an in vitro model of spinal cord injury.

    PubMed

    Mazzone, Graciela L; Veeraraghavan, Priyadharishini; Gonzalez-Inchauspe, Carlota; Nistri, Andrea; Uchitel, Osvaldo D

    2017-02-20

    In the spinal cord high extracellular glutamate evokes excitotoxic damage with neuronal loss and severe locomotor impairment. During the cell dysfunction process, extracellular pH becomes acid and may activate acid-sensing ion channels (ASICs) which could be important contributors to neurodegenerative pathologies. Our previous studies have shown that transient application of the glutamate analog kainate (KA) evokes delayed excitotoxic death of spinal neurons, while white matter is mainly spared. The present goal was to enquire if ASIC channels modulated KA damage in relation to locomotor network function and cell death. Mouse spinal cord slices were treated with KA (0.01 or 0.1mM) for 1h, and then washed out for 24h prior to analysis. RT-PCR results showed that KA (at 0.01mM concentration that is near-threshold for damage) increased mRNA expression of ASIC1a, ASIC1b, ASIC2 and ASIC3, an effect reversed by the ASIC inhibitor 4',6-diamidino-2-phenylindole (DAPI). A KA neurotoxic dose (0.1mM) reduced ASIC1a and ASIC2 expression. Cell viability assays demonstrated KA-induced large damage in spinal slices from mice with ASIC1a gene ablation. Likewise, immunohistochemistry indicated significant neuronal loss when KA was followed by the ASIC inhibitors DAPI or amiloride. Electrophysiological recording from ventral roots of isolated spinal cords showed that alternating oscillatory cycles were slowed down by 0.01mMKA, and intensely inhibited by subsequently applied DAPI or amiloride. Our data suggest that early rise in ASIC expression and function counteracted deleterious effects on spinal networks by raising the excitotoxicity threshold, a result with potential implications for improving neuroprotection.

  3. Signaling Noise Enhances Chemotactic Drift of E. coli

    NASA Astrophysics Data System (ADS)

    Flores, Marlo; Shimizu, Thomas S.; ten Wolde, Pieter Rein; Tostevin, Filipe

    2012-10-01

    Noise in the transduction of chemotactic stimuli to the flagellar motor of E. coli will affect the random run-and-tumble motion of the cell and the ability to perform chemotaxis. Here we use numerical simulations to show that an intermediate level of noise in the slow methylation dynamics enhances drift while not compromising localization near concentration peaks. A minimal model shows how such an optimal noise level arises from the interplay of noise and the dependence of the motor response on the network output. Our results suggest that cells can exploit noise to improve chemotactic performance.

  4. Proteolytic activation of proapoptotic kinase protein kinase Cδ by tumor necrosis factor α death receptor signaling in dopaminergic neurons during neuroinflammation

    PubMed Central

    2012-01-01

    Background The mechanisms of progressive dopaminergic neuronal loss in Parkinson’s disease (PD) remain poorly understood, largely due to the complex etiology and multifactorial nature of disease pathogenesis. Several lines of evidence from human studies and experimental models over the last decade have identified neuroinflammation as a potential pathophysiological mechanism contributing to disease progression. Tumor necrosis factor α (TNF) has recently emerged as the primary neuroinflammatory mediator that can elicit dopaminergic cell death in PD. However, the signaling pathways by which TNF mediates dopaminergic cell death have not been completely elucidated. Methods In this study we used a dopaminergic neuronal cell model and recombinant TNF to characterize intracellular signaling pathways activated during TNF-induced dopaminergic neurotoxicity. Etanercept and neutralizing antibodies to tumor necrosis factor receptor 1 (TNFR1) were used to block TNF signaling. We confirmed the results from our mechanistic studies in primary embryonic mesencephalic cultures and in vivo using the stereotaxic lipopolysaccharide (LPS) model of nigral dopaminergic degeneration. Results TNF signaling in dopaminergic neuronal cells triggered the activation of protein kinase Cδ (PKCδ), an isoform of the novel PKC family, by caspase-3 and caspase-8 dependent proteolytic cleavage. Both TNFR1 neutralizing antibodies and the soluble TNF receptor Etanercept blocked TNF-induced PKCδ proteolytic activation. Proteolytic activation of PKCδ was accompanied by translocation of the kinase to the nucleus. Notably, inhibition of PKCδ signaling by small interfering (si)RNA or overexpression of a PKCδ cleavage-resistant mutant protected against TNF-induced dopaminergic neuronal cell death. Further, primary dopaminergic neurons obtained from PKCδ knockout (−/−) mice were resistant to TNF toxicity. The proteolytic activation of PKCδ in the mouse substantia nigra in the neuroinflammatory LPS

  5. Local Cell Death Changes the Orientation of Cell Division in the Developing Drosophila Wing Imaginal Disc Without Using Fat or Dachsous as Orienting Signals

    PubMed Central

    Kale, Abhijit; Rimesso, Gerard; Baker, Nicholas E.

    2016-01-01

    Drosophila imaginal disc cells exhibit preferred cell division orientations according to location within the disc. These orientations are altered if cell death occurs within the epithelium, such as is caused by cell competition or by genotypes affecting cell survival. Both normal cell division orientations, and their orientations after cell death, depend on the Fat-Dachsous pathway of planar cell polarity (PCP). The hypothesis that cell death initiates a planar polarity signal was investigated. When clones homozygous for the pineapple eye (pie) mutation were made to initiate cell death, neither Dachsous nor Fat was required in pie cells for the re-orientation of nearby cells, indicating a distinct signal for this PCP pathway. Dpp and Wg were also not needed for pie clones to re-orient cell division. Cell shapes were evaluated in wild type and mosaic wing discs to assess mechanical consequences of cell loss. Although proximal wing disc cells and cells close to the dorso-ventral boundary were elongated in their preferred cell division axes in wild type discs, cell shapes in much of the wing pouch were symmetrical on average and did not predict their preferred division axis. Cells in pie mutant clones were slightly larger than their normal counterparts, consistent with mechanical stretching following cell loss, but no bias in cell shape was detected in the surrounding cells. These findings indicate that an unidentified signal influences PCP-dependent cell division orientation in imaginal discs. PMID:28030539

  6. 125I Seeds Radiation Induces Paraptosis-Like Cell Death via PI3K/AKT Signaling Pathway in HCT116 Cells

    PubMed Central

    Hu, Lelin; Wang, Hao; Zhao, Yong

    2016-01-01

    125I seeds brachytherapy implantation has been extensively performed in unresectable and rerecurrent rectal carcinoma. Many studies on the cancer-killing activity of 125I seeds radiation mainly focused on its ability to trigger apoptosis, which is the most well-known and dominant type of cell death induced by radiation. However our results showed some unique morphological features such as cell swelling, cytoplasmic vacuolation, and plasma membrane integrity, which is obviously different to apoptosis. In this study, clonogenic proliferation was carried out to assay survival fraction. Transmission electron microscopy was used to analyze ultrastructural and evaluate morphologic feature of HCT116 cells after exposure to 125I seeds radiation. Immunofluorescence analysis was used to detect the origin of cytoplasmic vacuoles. Flow cytometry analysis was employed to detect the size and granularity of HCT116 cells. Western blot was performed to measure the protein level of AIP1, caspase-3, AKT, p-Akt (Thr308), p-Akt (Ser473), and β-actin. We found that 125I seeds radiation activated PI3K/AKT signaling pathway and could trigger paraptosis-like cell death. Moreover, inhibitor of PI3K/AKT signaling pathway could inhibit paraptosis-like cell death induced by 125I seeds radiation. Our data suggest that 125I seeds radiation can induce paraptosis-like cell death via PI3K/AKT signaling pathway. PMID:28078301

  7. Local Cell Death Changes the Orientation of Cell Division in the Developing Drosophila Wing Imaginal Disc Without Using Fat or Dachsous as Orienting Signals.

    PubMed

    Kale, Abhijit; Rimesso, Gerard; Baker, Nicholas E

    2016-01-01

    Drosophila imaginal disc cells exhibit preferred cell division orientations according to location within the disc. These orientations are altered if cell death occurs within the epithelium, such as is caused by cell competition or by genotypes affecting cell survival. Both normal cell division orientations, and their orientations after cell death, depend on the Fat-Dachsous pathway of planar cell polarity (PCP). The hypothesis that cell death initiates a planar polarity signal was investigated. When clones homozygous for the pineapple eye (pie) mutation were made to initiate cell death, neither Dachsous nor Fat was required in pie cells for the re-orientation of nearby cells, indicating a distinct signal for this PCP pathway. Dpp and Wg were also not needed for pie clones to re-orient cell division. Cell shapes were evaluated in wild type and mosaic wing discs to assess mechanical consequences of cell loss. Although proximal wing disc cells and cells close to the dorso-ventral boundary were elongated in their preferred cell division axes in wild type discs, cell shapes in much of the wing pouch were symmetrical on average and did not predict their preferred division axis. Cells in pie mutant clones were slightly larger than their normal counterparts, consistent with mechanical stretching following cell loss, but no bias in cell shape was detected in the surrounding cells. These findings indicate that an unidentified signal influences PCP-dependent cell division orientation in imaginal discs.

  8. p53 death signal is mainly mediated by Nuc1(EndoG) in the yeast Saccharomyces cerevisiae.

    PubMed

    Palermo, Vanessa; Mangiapelo, Eleonora; Piloto, Cristina; Pieri, Luisa; Muscolini, Michela; Tuosto, Loretta; Mazzoni, Cristina

    2013-11-01

    The tumor suppressor p53 plays a central role in the regulation of cellular growth and apoptosis. In the yeast Saccharomyces cerevisiae, the overexpression of the human p53 leads to growth inhibition and apoptotic cell death on minimal medium. In the present work, we show that p53-expressing cells are more susceptible to cell death after an apoptotic stimulus such as H2O2. The analysis of mutants involved in yeast apoptosis-like death suggests that the observed cell death is Yca1 independent and mainly mediated through Nuc1p.

  9. Death receptor-independent FADD signalling triggers hepatitis and hepatocellular carcinoma in mice with liver parenchymal cell-specific NEMO knockout.

    PubMed

    Ehlken, H; Krishna-Subramanian, S; Ochoa-Callejero, L; Kondylis, V; Nadi, N E; Straub, B K; Schirmacher, P; Walczak, H; Kollias, G; Pasparakis, M

    2014-11-01

    Hepatocellular carcinoma (HCC) usually develops in the context of chronic hepatitis triggered by viruses or toxic substances causing hepatocyte death, inflammation and compensatory proliferation of liver cells. Death receptors of the TNFR superfamily regulate cell death and inflammation and are implicated in liver disease and cancer. Liver parenchymal cell-specific ablation of NEMO/IKKγ, a subunit of the IκB kinase (IKK) complex that is essential for the activation of canonical NF-κB signalling, sensitized hepatocytes to apoptosis and caused the spontaneous development of chronic hepatitis and HCC in mice. Here we show that hepatitis and HCC development in NEMO(LPC-KO) mice is triggered by death receptor-independent FADD-mediated hepatocyte apoptosis. TNF deficiency in all cells or conditional LPC-specific ablation of TNFR1, Fas or TRAIL-R did not prevent hepatocyte apoptosis, hepatitis and HCC development in NEMO(LPC-KO) mice. To address potential functional redundancies between death receptors we generated and analysed NEMO(LPC-KO) mice with combined LPC-specific deficiency of TNFR1, Fas and TRAIL-R and found that also simultaneous lack of all three death receptors did not prevent hepatocyte apoptosis, chronic hepatitis and HCC development. However, LPC-specific combined deficiency in TNFR1, Fas and TRAIL-R protected the NEMO-deficient liver from LPS-induced liver failure, showing that different mechanisms trigger spontaneous and LPS-induced hepatocyte apoptosis in NEMO(LPC-KO) mice. In addition, NK cell depletion did not prevent liver damage and hepatitis. Moreover, NEMO(LPC-KO) mice crossed into a RAG-1-deficient genetic background-developed hepatitis and HCC. Collectively, these results show that the spontaneous development of hepatocyte apoptosis, chronic hepatitis and HCC in NEMO(LPC-KO) mice occurs independently of death receptor signalling, NK cells and B and T lymphocytes, arguing against an immunological trigger as the critical stimulus driving

  10. Rotating machine fault diagnosis through enhanced stochastic resonance by full-wave signal construction

    NASA Astrophysics Data System (ADS)

    Lu, Siliang; He, Qingbo; Zhang, Haibin; Kong, Fanrang

    2017-02-01

    This study proposes a full-wave signal construction (FSC) strategy for enhancing rotating machine fault diagnosis by exploiting stochastic resonance (SR). The FSC strategy is utilized to transform a half-wave signal (e.g., an envelope signal) into a full-wave one by conducting a Mirror-Cycle-Add (MCA) operation. The constructed full-wave signal evenly modulates the bistable potential and makes the potential tilt back and forth smoothly. This effect provides the equivalent transition probabilities of particle bounce between the two potential wells. A stable SR output signal with better periodicity, which is beneficial to periodic signal detection, can be obtained. In addition, the MCA operation can improve the input signal-to-noise ratio by enhancing the periodic component while attenuating the noise components. These two advantages make the proposed FSCSR method surpass the traditional SR method in fault signal processing. Performance evaluation is conducted by numerical analysis and experimental verification. The proposed MCA-based FSC strategy has the potential to be a universal signal pre-processing technique. Moreover, the proposed FSCSR method can be used in rotating machine fault diagnosis and other areas related to weak signal detection.

  11. Supramolecular Nanofibers Enhance Growth Factor Signaling by Increasing Lipid Raft Mobility

    SciTech Connect

    Newcomb, Christina J.; Sur, Shantanu; Lee, Sungsoo S.; Yu, Jeong Min; Zhou, Yan; Snead, Malcolm L.; Stupp, Samuel I.

    2016-04-12

    The nanostructures of self-assembling biomaterials have been previously designed to tune the release of growth factors in order to optimize biological repair and regeneration. We report here on the discovery that weakly cohesive peptide nanostructures in terms of intermolecular hydrogen bonding, when combined with low concentrations of osteogenic growth factor, enhance both BMP-2 and Wnt mediated signaling in myoblasts and bone marrow stromal cells, respectively. Conversely, analogous nanostructures with enhanced levels of internal hydrogen bonding and cohesion lead to an overall reduction in BMP-2 signaling. We propose that the mechanism for enhanced growth factor signaling by the nanostructures is related to their ability to increase diffusion within membrane lipid rafts. The phenomenon reported here could lead to new nanomedicine strategies to mediate growth factor signaling for translational targets.

  12. Inflammation Enhances the Risks of Stroke and Death in Chronic Chagas Disease Patients

    PubMed Central

    Guedes, Paulo Marcos Matta; de Andrade, Cléber Mesquita; Nunes, Daniela Ferreira; de Sena Pereira, Nathalie; Queiroga, Tamyres Bernadete Dantas; Machado-Coelho, George Luiz Lins; Nascimento, Manuela Sales Lima; Do-Valle-Matta, Maria Adelaide; da Câmara, Antônia Cláudia Jácome; Chiari, Egler; Galvão, Lúcia Maria da Cunha

    2016-01-01

    Ischemic strokes have been implicated as a cause of death in Chagas disease patients. Inflammation has been recognized as a key component in all ischemic processes, including the intravascular events triggered by vessel interruption, brain damage and repair. In this study, we evaluated the association between inflammatory markers and the death risk (DR) and stroke risk (SR) of patients with different clinical forms of chronic Chagas disease. The mRNA expression levels of cytokines, transcription factors expressed in the adaptive immune response (Th1, Th2, Th9, Th17, Th22 and regulatory T cell), and iNOS were analyzed by real-time PCR in peripheral blood mononuclear cells of chagasic patients who exhibited the indeterminate, cardiac, digestive and cardiodigestive clinical forms of the disease, and the levels of these transcripts were correlated with the DR and SR. Cardiac patients exhibited lower mRNA expression levels of GATA-3, FoxP3, AHR, IL-4, IL-9, IL-10 and IL-22 but exhibited higher expression of IFN-γ and TNF-α compared with indeterminate patients. Digestive patients showed similar levels of GATA-3, IL-4 and IL-10 than indeterminate patients. Cardiodigestive patients exhibited higher levels of TNF-α compared with indeterminate and digestive patients. Furthermore, we demonstrated that patients with high DR and SR exhibited lower GATA-3, FoxP3, and IL-10 expression and higher IFN-γ, TNF-α and iNOS mRNA expression than patients with low DR and SR. A negative correlation was observed between Foxp3 and IL-10 mRNA expression and the DR and SR. Moreover, TNF-α and iNOS expression was positively correlated with DR and SR. Our data suggest that an inflammatory imbalance in chronic Chagas disease patients is associated with a high DR and SR. This study provides a better understanding of the stroke pathobiology in the general population and might aid the development of therapeutic strategies for controlling the morbidity and mortality of Chagas disease. PMID

  13. Inflammation Enhances the Risks of Stroke and Death in Chronic Chagas Disease Patients.

    PubMed

    Guedes, Paulo Marcos Matta; de Andrade, Cléber Mesquita; Nunes, Daniela Ferreira; de Sena Pereira, Nathalie; Queiroga, Tamyres Bernadete Dantas; Machado-Coelho, George Luiz Lins; Nascimento, Manuela Sales Lima; Do-Valle-Matta, Maria Adelaide; da Câmara, Antônia Cláudia Jácome; Chiari, Egler; Galvão, Lúcia Maria da Cunha

    2016-04-01

    Ischemic strokes have been implicated as a cause of death in Chagas disease patients. Inflammation has been recognized as a key component in all ischemic processes, including the intravascular events triggered by vessel interruption, brain damage and repair. In this study, we evaluated the association between inflammatory markers and the death risk (DR) and stroke risk (SR) of patients with different clinical forms of chronic Chagas disease. The mRNA expression levels of cytokines, transcription factors expressed in the adaptive immune response (Th1, Th2, Th9, Th17, Th22 and regulatory T cell), and iNOS were analyzed by real-time PCR in peripheral blood mononuclear cells of chagasic patients who exhibited the indeterminate, cardiac, digestive and cardiodigestive clinical forms of the disease, and the levels of these transcripts were correlated with the DR and SR. Cardiac patients exhibited lower mRNA expression levels of GATA-3, FoxP3, AHR, IL-4, IL-9, IL-10 and IL-22 but exhibited higher expression of IFN-γ and TNF-α compared with indeterminate patients. Digestive patients showed similar levels of GATA-3, IL-4 and IL-10 than indeterminate patients. Cardiodigestive patients exhibited higher levels of TNF-α compared with indeterminate and digestive patients. Furthermore, we demonstrated that patients with high DR and SR exhibited lower GATA-3, FoxP3, and IL-10 expression and higher IFN-γ, TNF-α and iNOS mRNA expression than patients with low DR and SR. A negative correlation was observed between Foxp3 and IL-10 mRNA expression and the DR and SR. Moreover, TNF-α and iNOS expression was positively correlated with DR and SR. Our data suggest that an inflammatory imbalance in chronic Chagas disease patients is associated with a high DR and SR. This study provides a better understanding of the stroke pathobiology in the general population and might aid the development of therapeutic strategies for controlling the morbidity and mortality of Chagas disease.

  14. Toward resolving deep neoaves phylogeny: data, signal enhancement, and priors.

    PubMed

    Pratt, Renae C; Gibb, Gillian C; Morgan-Richards, Mary; Phillips, Matthew J; Hendy, Michael D; Penny, David

    2009-02-01

    We report three developments toward resolving the challenge of the apparent basal polytomy of neoavian birds. First, we describe improved conditional down-weighting techniques to reduce noise relative to signal for deeper divergences and find increased agreement between data sets. Second, we present formulae for calculating the probabilities of finding predefined groupings in the optimal tree. Finally, we report a significant increase in data: nine new mitochondrial (mt) genomes (the dollarbird, New Zealand kingfisher, great potoo, Australian owlet-nightjar, white-tailed trogon, barn owl, a roadrunner [a ground cuckoo], New Zealand long-tailed cuckoo, and the peach-faced lovebird) and together they provide data for each of the six main groups of Neoaves proposed by Cracraft J (2001). We use his six main groups of modern birds as priors for evaluation of results. These include passerines, cuckoos, parrots, and three other groups termed "WoodKing" (woodpeckers/rollers/kingfishers), "SCA" (owls/potoos/owlet-nightjars/hummingbirds/swifts), and "Conglomerati." In general, the support is highly significant with just two exceptions, the owls move from the "SCA" group to the raptors, particularly accipitrids (buzzards/eagles) and the osprey, and the shorebirds may be an independent group from the rest of the "Conglomerati". Molecular dating mt genomes support a major diversification of at least 12 neoavian lineages in the Late Cretaceous. Our results form a basis for further testing with both nuclear-coding sequences and rare genomic changes.

  15. Bifunctional Alkylating Agent-Induced p53 and Nonclassical Nuclear Factor kB Responses and Cell Death are Altered by Caffeic Acid Phenethyl Ester: A Potential Role for Antioxidant/Electrophilic Response-Element Signaling

    DTIC Science & Technology

    2007-01-01

    modify DNA and protein. The roles of nuclear factor kappa B (NF-kB) and p53, transcription factors involved in inflammatory and cell death signaling, were...of ARE/EpRE pathways may be effective strategies to delineate mechanisms of action of BFA-induced inflammation and cell death signaling in immortalized versus normal skin systems.

  16. Enhanced expression of Programmed cell death 1 (PD-1) protein in benign vascular anomalies.

    PubMed

    Amaya, Clarissa N; Wians, Frank H; Bryan, Brad A; Torabi, Alireza

    2017-04-01

    Programmed cell death 1 (PD-1) and its ligands have been shown to play a significant role in evasion of malignant tumour cells from the immune system. Last year, the United States Food and Drug Administration (FDA) approved anti-PD-1 inhibitors for treatment of non-small cell lung carcinoma and recently has approved anti-PD-L1 blocker for treatment of metastatic urothelial cell carcinoma. However, the role that the immune system might have on benign tumours including vascular anomalies has received less attention. In this study, we evaluated PD-1 and PD-L1 expression on two benign vascular anomalies: infantile haemangiomas and venous malformations. Tissue microarrays (TMAs) from these two entities were stained for PD-1 and PD-L1 antibodies. Blood vessels from normal tissue were used as control. The endothelial cells in both infantile haemangioma and venous malformation showed high expression of PD-1 but were negative for PD-L1. Endothelial cells within the blood vessels in normal tissues were negative for both PD-1 and PD-L1. Our results showed over-expression of PD-1 in subsets of vascular anomalies, while PD-L1 was negative. This would raise the possibility of immunotherapy in benign vascular tumour when other options are exhausted.

  17. Use and Protection of GPS Sidelobe Signals for Enhanced Navigation Performance in High Earth Orbit

    NASA Technical Reports Server (NTRS)

    Parker, Joel J. K.; Valdez, Jennifer E.; Bauer, Frank H.; Moreau, Michael C.

    2016-01-01

    GPS (Global Positioning System) Space Service Volume (SSV) signal environment is from 3,000-36,000 kilometers altitude. Current SSV specifications only capture performance provided by signals transmitted within 23.5(L1) or 26(L2-L5) off-nadir angle. Recent on-orbit data lessons learned show significant PNT (Positioning, Navigation and Timing) performance improvements when the full aggregate signal is used. Numerous military civil operational missions in High Geosynchronous Earth Orbit (HEOGEO) utilize the full signal to enhance vehicle PNT performance

  18. A Comparison of Signal Enhancement Methods for Extracting Tonal Acoustic Signals

    NASA Technical Reports Server (NTRS)

    Jones, Michael G.

    1998-01-01

    The measurement of pure tone acoustic pressure signals in the presence of masking noise, often generated by mean flow, is a continual problem in the field of passive liner duct acoustics research. In support of the Advanced Subsonic Technology Noise Reduction Program, methods were investigated for conducting measurements of advanced duct liner concepts in harsh, aeroacoustic environments. This report presents the results of a comparison study of three signal extraction methods for acquiring quality acoustic pressure measurements in the presence of broadband noise (used to simulate the effects of mean flow). The performance of each method was compared to a baseline measurement of a pure tone acoustic pressure 3 dB above a uniform, broadband noise background.

  19. Sex steroid blockade enhances thymopoiesis by modulating Notch signaling

    PubMed Central

    Tsai, Jennifer J.; Holland, Amanda M.; Wertheimer, Tobias; Yu, Vionnie W.C.; Zakrzewski, Johannes L.; Tuckett, Andrea Z.; Singer, Natalie V.; West, Mallory L.; Smith, Odette M.; Young, Lauren F.; Kreines, Fabiana M.; Levy, Emily R.; Boyd, Richard L.; Scadden, David T.

    2014-01-01

    Paradoxical to its importance for generating a diverse T cell repertoire, thymic function progressively declines throughout life. This process has been at least partially attributed to the effects of sex steroids, and their removal promotes enhanced thymopoiesis and recovery from immune injury. We show that one mechanism by which sex steroids influence thymopoiesis is through direct inhibition in cortical thymic epithelial cells (cTECs) of Delta-like 4 (Dll4), a Notch ligand crucial for the commitment and differentiation of T cell progenitors in a dose-dependent manner. Consistent with this, sex steroid ablation (SSA) led to increased expression of Dll4 and its downstream targets. Importantly, SSA induced by luteinizing hormone-releasing hormone (LHRH) receptor antagonism bypassed the surge in sex steroids caused by LHRH agonists, the gold standard for clinical ablation of sex steroids, thereby facilitating increased Dll4 expression and more rapid promotion of thymopoiesis. Collectively, these findings not only reveal a novel mechanism underlying improved thymic regeneration upon SSA but also offer an improved clinical strategy for successfully boosting immune function. PMID:25332287

  20. An enhanced sparse representation strategy for signal classification

    NASA Astrophysics Data System (ADS)

    Zhou, Yin; Gao, Jinglun; Barner, Kenneth E.

    2012-06-01

    Sparse representation based classification (SRC) has achieved state-of-the-art results on face recognition. It is hence desired to extend its power to a broader range of classification tasks in pattern recognition. SRC first encodes a query sample as a linear combination of a few atoms from a predefined dictionary. It then identifies the label by evaluating which class results in the minimum reconstruction error. The effectiveness of SRC is limited by an important assumption that data points from different classes are not distributed along the same radius direction. Otherwise, this approach will lose their discrimination ability, even though data from different classes are actually well-separated in terms of Euclidean distance. This assumption is reasonable for face recognition as images of the same subject under different intensity levels are still considered to be of same-class. However, the assumption is not always satisfied when dealing with many other real-world data, e.g., the Iris dataset, where classes are stratified along the radius direction. In this paper, we propose a new coding strategy, called Nearest- Farthest Neighbors based SRC (NF-SRC), to effectively overcome the limitation within SRC. The dictionary is composed of both the Nearest Neighbors and the Farthest Neighbors. While the Nearest Neighbors are used to narrow the selection of candidate samples, the Farthest Neighbors are employed to make the dictionary more redundant. NF-SRC encodes each query signal in a greedy way similar to OMP. The proposed approach is evaluated over extensive experiments. The encouraging results demonstrate the feasibility of the proposed method.

  1. Factors enhancing adherence of toxigenic Staphylococcus aureus to epithelial cells and their possible role in sudden infant death syndrome.

    PubMed

    Saadi, A T; Blackwell, C C; Raza, M W; James, V S; Stewart, J; Elton, R A; Weir, D M

    1993-06-01

    Toxigenic strains of Staphylococcus aureus have been suggested to play a role in sudden infant death syndrome (SIDS). In this study we examined two factors that might enhance binding of toxigenic staphylococci to epithelial cells of infants in the age range in which cot deaths are prevalent: expression of the Lewis(a) antigen and infection with respiratory syncytial virus (RSV). By flow cytometry we demonstrated that binding of three toxigenic strains of S. aureus to cells from nonsecretors was significantly greater than to cells of secretors. Pre-treatment of epithelial cells with monoclonal anti-Lewis(a) or anti-type-1 precursor significantly reduced bacterial binding (P < 0.01); however, attachment of the bacteria correlated only with the amount of Lewis(a) antigen detected on the cells (P < 0.01). HEp-2 cells infected with RSV bound significantly more bacteria than uninfected cells. These findings are discussed in context of factors previously associated with SIDS (mother's smoking, bottle feeding and the prone sleeping position) and a hypothesis proposed to explain some cases of SIDS.

  2. Fermented wheat germ extract induced cell death and enhanced cytotoxicity of Cisplatin and 5-Fluorouracil on human hepatocellular carcinoma cells.

    PubMed

    Tai, Cheng-Jeng; Wang, Wen-Ching; Wang, Chien-Kai; Wu, Chih-Hsiung; Yang, Mei-Due; Chang, Yu-Jia; Jian, Jiun-Yu; Tai, Chen-Jei

    2013-01-01

    Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Due to the difficulties of early diagnosis, curative treatments are not available for most patients. Palliative treatments such as chemotherapy are often associated with low response rate, strong adverse effects and limited clinical benefits for patients. The alternative approaches such as fermented wheat germ extract (FWGE) with anti-tumor efficacy may provide improvements in the clinical outcome of current therapy for HCC. This study aimed to clarify antitumor efficacy of FWGE and the combination drug effect of FWGE with chemotherapeutic agents, cisplatin and 5-fluorouracil (5-Fu) in human HCC cells, HepG2, Hep3B, and HepJ5. The present study indicated that FWGE exhibited potential to suppress HepG2, Hep3B, and HepJ5 cells, with the half maximal inhibitory concentrations (IC50) of FWGE were 0.494, 0.371 and 1.524 mg/mL, respectively. FWGE also induced Poly (Adenosine diphosphate ribose) polymerase (PARP) associated cell death in Hep3B cells. Moreover, the FWGE treatment further enhanced the cytotoxicity of cisplatin in all tested HCC cells, and cytotoxicity of 5-Fu in a synergistic manner in HepJ5 cells. Collectively, the results identified the anti-tumor efficacy of FWGE in HCC cells and suggested that FWGE can be used as a supplement to effectively improve the tumor suppression efficiency of cisplatin and 5-Fu in HCC cells.

  3. Entamoeba histolytica P-glycoprotein (EhPgp) inhibition, induce trophozoite acidification and enhance programmed cell death.

    PubMed

    Medel Flores, Olivia; Gómez García, Consuelo; Sánchez Monroy, Virgina; Villalba Magadaleno, José D'Artagnan; Nader García, Elvira; Pérez Ishiwara, D Guillermo

    2013-11-01

    Programmed cell death (PCD) is induced in Entamoeba histolytica by a variety of stimuli in vitro and in vivo. In mammals, intracellular acidification serves as a global switch for inactivating cellular processes and initiates molecular mechanisms implicated in the destruction of the genome. In contrast, intracellular alkalinization produced by P-glycoprotein overexpression in multidrug-resistant cells has been related to apoptosis resistance. Our previous studies showed that overexpression of E. histolytica P-glycoprotein (PGP) altered chloride-dependent currents and triggered trophozoite swelling, the reverse process of cell shrinkage produced during PCD. Here we showed that antisense inhibition of PGP expression produced a synchronous death of trophozoites and the enhancement of biochemical and morphological characteristics of PCD induced by G418. The nucleus was contracted, and the nuclear membrane was disrupted. Moreover, chromatin was extensively fragmented. Ca(2+) concentration was increased, while the intracellular pH (ipH) was acidified. In contrast, PGP overexpression prevented intracellular acidification and circumvented the apoptotic effect of G418.

  4. Autophagy-enhancing drug carbamazepine diminishes hepatocellular death in fibrinogen storage disease.

    PubMed

    Puls, Florian; Goldschmidt, Imeke; Bantel, Heike; Agne, Clemens; Bröcker, Verena; Dämmrich, Maximilian; Lehmann, Ulrich; Berrang, Jens; Pfister, Eva-Doreen; Kreipe, Hans Heinrich; Baumann, Ulrich

    2013-09-01

    Fibrinogen storage disease (FSD) is a rare autosomal-dominant hereditary disorder characterized by hypofibrinogenemia and accumulation of fibrinogen aggregates within the hepatocellular endoplasmatic reticulum (ER). Some FSD patients present with elevated amino-transferases and fibrosis/cirrhosis similar to alpha-1-antitrypsin deficiency (ATD), also an ER storage disease. Pharmacological stimulation of autophagy has been shown to mediate clearance of protein aggregates and halt progression of liver fibrosis in in vivo models of ATD. Our aim was to evaluate the presence of autophagy and a possible response to autophagy-enhancing therapy in patients with FSD. Hepatic fibrosis was assessed by transient elastography in 2 newly identified FSD families with fibrinogen Aguadilla and Brescia mutations, encompassing 8 affected members. Available liver biopsies were assessed for autophagy. Two patients, who had had elevated alanine amino-transaminase levels (2-5 above upper limit of normal), were treated with the autophagy enhancer carbamazepine (CBZ). Transient elastography did not show evidence of significant fibrosis in any affected family members. Quantitative electron microscopy of one patient showed a 5.15-fold increase of late stage autophagocytic vacuoles compared to control livers. CBZ at low anticonvulsive treatment levels led to rapid normalization of alanine-aminotransferase and decrease of caspase-cleaved and uncleaved cytokeratin-18 fragments (M30 and M65). These effects reversed after discontinuation of treatment. Response to CBZ may be mediated by pharmacologically enhanced autophagy resulting in reduction of aggregate-related toxicity in FSD. These results suggest clinical applicability of pharmacological stimulation of autophagy in FSD, but potentially also in other related disorders.

  5. Evidence against signal enhancement as a mechanism of direct selection by color.

    PubMed

    Vierck, Esther; Miller, Jeff

    2007-04-01

    Two of the possible mechanisms that have been put forward to explain precuing effects are signal enhancement and uncertainty reduction. Signal enhancement leads to processing advantages for valid information because the signal at the known input channel is enhanced, whereas uncertainty reduction allows observers to ignore confusing distractor items in a display. Both mechanisms have been reported to be involved in location precuing, but it is still unclear which of these two mechanisms is responsible for color cuing effects. Two experiments are reported in which expectancy for a certain color in a single-item display was created. Targetswere presented briefly and were masked. If color cues produce signal enhancement, then a color cuing effect should result. If color cues only allow uncertainty reduction, however, there should be no color cuing effect because there are no distractors in single-item displays. The results of both experiments favor uncertainty reduction as the mechanism behind color cuing, because no signs of signal enhancement-based cuing effects were observed.

  6. The mutual effect of metal sample and turboflame in LIBS signal enhancement

    NASA Astrophysics Data System (ADS)

    Ghezelbash, M.; Mousavi, S. J.; Majd, A. E.; Darbani, S. M. R.; Saghafifar, H.; Maleki, A.

    2016-08-01

    The main aim of the present study is to evaluate the mutual effect of copper sample and turboflame in laser induced breakdown spectroscopy (LIBS) signal enhancement. The use of copper sample leads to a signal enhancement in CN ( B 2Σ+- X 2Σ+) 384.2-388.4 nm molecular transition, N742nm, N744nm, N746nm (a triplet generated by the fine splitting of the 2 s 22 p 2(3 P)3 s-2 s 22 p 2(3 P)3 p transition) and Hα, 656.3 nm (as a flame inductor) atomic lines analysis. Additionally, increase in copper sample temperature with flame can enhance the Cu atomic line intensities (as copper sample inductors). Moreover, in this paper, the comparison between turboflame and alcohol flame on LIBS analysis was studied. LIBS signal intensity variation in a turboflame and turboflame coupled with copper sample at different laser pulse energies indicated that the low laser pulse energy could be compensated by using a copper sample that is coupled with turboflame and improved LIBS signal enhancement. For flames analysis, the use of metal sample in LIBS method is demonstrated to be costeffective, compact, and capable of signal enhancement.

  7. Oxidative stress activates the TRPM2-Ca(2+)-CaMKII-ROS signaling loop to induce cell death in cancer cells.

    PubMed

    Wang, Qian; Huang, Lihong; Yue, Jianbo

    2016-12-20

    High intracellular levels of reactive oxygen species (ROS) cause oxidative stress that results in numerous pathologies, including cell death. Transient potential receptor melastatin-2 (TRPM2), a Ca(2+)-permeable cation channel, is mainly activated by intracellular adenosine diphosphate ribose (ADPR) in response to oxidative stress. Here we studied the role and mechanisms of TRPM2-mediated Ca(2+) influx on oxidative stress-induced cell death in cancer cells. We found that oxidative stress activated the TRPM2-Ca(2+)-CaMKII cascade to inhibit early autophagy induction, which ultimately led to cell death in TRPM2 expressing cancer cells. On the other hand, TRPM2 knockdown switched cells from cell death to autophagy for survival in response to oxidative stress. Moreover, we found that oxidative stress activated the TRPM2-CaMKII cascade to further induce intracellular ROS production, which led to mitochondria fragmentation and loss of mitochondrial membrane potential. In summary, our data demonstrated that oxidative stress activates the TRPM2-Ca(2+)-CaMKII-ROS signal loop to inhibit autophagy and induce cell death.

  8. [A modified speech enhancement algorithm for electronic cochlear implant and its digital signal processing realization].

    PubMed

    Wang, Yulin; Tian, Xuelong

    2014-08-01

    In order to improve the speech quality and auditory perceptiveness of electronic cochlear implant under strong noise background, a speech enhancement system used for electronic cochlear implant front-end was constructed. Taking digital signal processing (DSP) as the core, the system combines its multi-channel buffered serial port (McBSP) data transmission channel with extended audio interface chip TLV320AIC10, so speech signal acquisition and output with high speed are realized. Meanwhile, due to the traditional speech enhancement method which has the problems as bad adaptability, slow convergence speed and big steady-state error, versiera function and de-correlation principle were used to improve the existing adaptive filtering algorithm, which effectively enhanced the quality of voice communications. Test results verified the stability of the system and the de-noising performance of the algorithm, and it also proved that they could provide clearer speech signals for the deaf or tinnitus patients.

  9. Wnt/β-catenin signaling enhances hypoxia-induced epithelial-mesenchymal transition in hepatocellular carcinoma via crosstalk with hif-1α signaling.

    PubMed

    Zhang, Qi; Bai, Xueli; Chen, Wei; Ma, Tao; Hu, Qida; Liang, Chao; Xie, Shangzhi; Chen, Conglin; Hu, Liqiang; Xu, Shiguo; Liang, Tingbo

    2013-05-01

    Epithelial-mesenchymal transition (EMT) is a critical process for tumor invasion and metastasis. Hypoxia may induce EMT, and upregulated β-catenin expression has been found in various tumors. In this study, we investigate the role of β-catenin in hypoxia-induced EMT in hepatocellular carcinoma (HCC). Induction of EMT in HCC cell lines by hypoxia was confirmed by altered morphology, expression change of EMT-associated markers and enhanced invasion capacity. We showed that hypoxia-induced EMT could be enhanced by addition of recombinant Wnt3a while it was repressed by β-catenin small interfering RNA. An interaction between β-catenin and hypoxia-induced factor-1α (hif-1α) was found, and an underlying competition for β-catenin between hif-1α and T-cell factor-4 was implied. Notably, increased hif-1α activity was accompanied with more significant EMT features. We also showed that the pro-EMT effect of β-catenin in hypoxia was deprived in the absence of hif-1α. Moreover, β-catenin was found to be responsible for the maintenance of viability and proliferation for tumor cells undergoing hypoxia. We further showed a correlation between hif-1α and β-catenin expression, and corresponding expression of EMT-associated markers in human HCC tissues. Our results suggest that Wnt/β-catenin signaling enhances hypoxia-induced EMT in HCC by increasing the EMT-associated activity of hif-1α and preventing tumor cell death.

  10. Enhanced correlation of received power-signal fluctuations in bidirectional optical links

    NASA Astrophysics Data System (ADS)

    Minet, Jean; Vorontsov, Mikhail A.; Polnau, Ernst; Dolfi, Daniel

    2013-02-01

    A study of the correlation between the power signals received at both ends of bidirectional free-space optical links is presented. By use of the quasi-optical approximation, we show that an ideal (theoretically 100%) power-signal correlation can be achieved in optical links with specially designed monostatic transceivers based on single-mode fiber collimators. The theoretical prediction of enhanced correlation is supported both by experiments conducted over a 7 km atmospheric path and wave optics numerical analysis of the corresponding bidirectional optical link. In the numerical simulations, we also compare correlation properties of received power signals for different atmospheric conditions and for optical links with monostatic and bistatic geometries based on single-mode fiber collimator and on power-in-the-bucket transceiver types. Applications of the observed phenomena for signal fading mitigation and turbulence-enhanced communication link security in free-space laser communication links are discussed.

  11. Camptothecin Enhances Cell Death Induced by (177)Lu-EDTMP in Osteosarcoma Cells.

    PubMed

    Kumar, Chandan; Vats, Kusum; Lohar, Sharad P; Korde, Aruna; Samuel, Grace

    2014-10-01

    Lutetium-177 is an assured therapeutic radionuclide with favorable half-life and suitable β(-) energy. Radiolabeled (177)Lu-EDTMP (Ethylenediamine tetramethylene phosphonic acid) is by and large used for bone pain palliation in cancer patients. In vitro cell studies are carried out in osteosarcoma cells MG-63 to evaluate the combined effect of anticancer drug camptothecin (CPT) and (177)Lu-EDTMP. Two concentrations of (177)Lu-EDTMP (3.7 and 37 MBq) were incubated with MG63 cell line for 48 hours with and without pretreatment of CPT (10 nM) for 1 hour. After completion of incubation, the cells were harvested and cellular toxicity was estimated by LDH, MTT, and trypan blue dye. Apoptotic DNA fragmentation was estimated by ELISA kit. The expression of proteins such as bcl2, PARP, and MAPK (mitogen-activated protein kinase) that were related to apoptotic signaling pathways was assessed by western blotting. The results indicated that cellular toxicity and apoptosis were relatively higher in MG63 cells that were treated with CPT prior to treating with (177)Lu-EDTMP in comparison with the corresponding individual controls.

  12. A novel homozygous Fas ligand mutation leads to early protein truncation, abrogation of death receptor and reverse signaling and a severe form of the autoimmune lymphoproliferative syndrome.

    PubMed

    Nabhani, Schafiq; Hönscheid, Andrea; Oommen, Prasad T; Fleckenstein, Bernhard; Schaper, Jörg; Kuhlen, Michaela; Laws, Hans-Jürgen; Borkhardt, Arndt; Fischer, Ute

    2014-12-01

    We report a novel type of mutation in the death ligand FasL that was associated with a severe phenotype of the autoimmune lymphoproliferative syndrome in two patients. A frameshift mutation in the intracellular domain led to complete loss of FasL expression. Cell death signaling via its receptor and reverse signaling via its intracellular domain were completely abrogated. In vitro lymphocyte proliferation induced by weak T cell receptor stimulation could be blocked and cell death was induced by engagement of FasL in T cells derived from healthy individuals and a heterozygous carrier, but not in FasL-deficient patient derived cells. Expression of genes implicated in lymphocyte proliferation and activation (CCND1, NFATc1, NF-κB1) was increased in FasL-deficient T cells and could not be downregulated by FasL engagement as in healthy cells. Our data thus suggest, that deficiency in FasL reverse signaling may contribute to the clinical lymphoproliferative phenotype of ALPS.

  13. Transient enhancement of spike-evoked calcium signaling by a serotonergic interneuron.

    PubMed

    Hill, Evan S; Sakurai, Akira; Katz, Paul S

    2008-11-01

    Enhancement of presynaptic Ca(2+) signals is widely recognized as a potential mechanism for heterosynaptic potentiation of neurotransmitter release. Here we show that stimulation of a serotonergic interneuron increased spike-evoked Ca(2+) in a manner consistent with its neuromodulatory effect on synaptic transmission. In the gastropod mollusk, Tritonia diomedea, stimulation of a serotonergic dorsal swim interneuron (DSI) at physiological rates heterosynaptically enhances the strength of output synapses made by another swim interneuron, C2, onto neurons in the pedal ganglion. Using intracellular electrophysiological recording combined with real-time confocal imaging of C2 (loaded with Oregon Green Bapta 1), it was determined that DSI stimulation increases the amplitude of spike-evoked Ca(2+) signals in C2 without altering basal Ca(2+) signals. This neuromodulatory action was restricted to distal neurites of C2 where synapses with pedal neurons are located. The effect of DSI stimulation on C2 spike-evoked Ca(2+) signals resembled DSI heterosynaptic enhancement of C2 synapses in several measures: both decayed within 15 s, both were abolished by the serotonin receptor antagonist, methysergide, and both were independent of DSI's depolarizing actions on C2. A brief puff of serotonin could mimic the enhancement of spike-evoked Ca(2+) signals in the distal neurites of C2, but larger puffs or bath-applied serotonin elicited nonphysiological effects. These results suggest that DSI heterosynaptic enhancement of C2 synaptic strength may be mediated by a local enhancement of spike-evoked Ca(2+) signals in the distal neurites of C2.

  14. Signal Enhancement with Stacked Magnets for High-Resolution Radio Frequency Glow Discharge Mass Spectrometry.

    PubMed

    Wei, Juan; Dong, Jiangli; Zhuo, Shangjun; Qian, Rong; Fang, Yuanxing; Chen, Qiao; Patel, Ekbal

    2017-01-17

    A method for signal enhancement utilizing stacked magnets was introduced into high-resolution radio frequency glow discharge-mass spectrometry (rf-GD-MS) for significantly improved analysis of inorganic materials. Compared to the block magnet, the stacked magnets method was able to achieve 50-59% signal enhancement for typical elements in Y2O3, BSO, and BTN samples. The results indicated that signal was enhanced as the increase of discharge pressure from 1.3 to 8.0 mPa, the increase of rf-power from 10 to 50 W with a frequency of 13.56 MHz, the decrease of sample thickness, and the increase of number of stacked magnets. The possible mechanism for the signal enhancement was further probed using the software "Mechanical APDL (ANSYS) 14.0". It was found that the distinct oscillated magnetic field distribution from the stacked magnets was responsible for signal enhancement, which could extend the movement trajectories of electrons and increase the collisions between the electrons and neutral particles to increase the ionization efficiency. Two NIST samples were used for the validation of the method, and the results suggested that relative errors were within 13% and detection limit for six transverse stacked magnets could reach as low as 0.0082 μg g(-1). Additionally, the stability of the method was also studied. RSD within 15% of the elements in three nonconducting samples could be obtained during the sputtering process. Together, the results showed that the signal enhancement method with stacked magnets could offer great promises in providing a sensitive, stable, and facile solution for analyzing the nonconducting materials.

  15. Low dose gamma irradiation enhances defined signaling components of intercellular reactive oxygen-mediated apoptosis induction

    NASA Astrophysics Data System (ADS)

    Bauer, G.

    2011-01-01

    Transformed cells are selectively removed by intercellular ROS-mediated induction of apoptosis. Signaling is based on the HOCl and the NO/peroxynitrite pathway (major pathways) and the nitryl chloride and the metal-catalyzed Haber-Weiss pathway (minor pathways). During tumor progression, resistance against intercellular induction of apoptosis is acquired through expression of membrane-associated catalase. Low dose radiation of nontransformed cells has been shown to enhance intercellular induction of apoptosis. The present study was performed to define the signaling components which are modulated by low dose gamma irradiation. Low dose radiation induced the release of peroxidase from nontransformed, transformed and tumor cells. Extracellular superoxide anion generation was strongly enhanced in the case of transformed cells and tumor cells, but not in nontransformed cells. Enhancement of peroxidase release and superoxide anion generation either increased intercellular induction of apoptosis of transformed cells, or caused a partial protection under specific signaling conditions. In tumor cells, low dose radiation enhanced the production of major signaling components, but this had no effect on apoptosis induction, due to the strong resistance mechanism of tumor cells. Our data specify the nature of low dose radiation-induced effects on specific signaling components of intercellular induction of apoptosis at defined stages of multistep carcinogenesis.

  16. Myc inhibits JNK-mediated cell death in vivo.

    PubMed

    Huang, Jiuhong; Feng, Yu; Chen, Xinhong; Li, Wenzhe; Xue, Lei

    2017-04-01

    The proto-oncogene Myc is well known for its roles in promoting cell growth, proliferation and apoptosis. However, in this study, we found from a genetic screen that Myc inhibits, rather than promotes, cell death triggered by c-Jun N-terminal kinase (JNK) signaling in Drosophila. Firstly, expression of Drosophila Myc (dMyc) suppresses, whereas loss of dMyc enhances, ectopically activated JNK signaling-induced cell death. Secondly, dMyc impedes physiologically activated JNK pathway-mediated cell death. Thirdly, loss of dMyc triggers JNK pathway activation and JNK-dependent cell death. Finally, the mammalian cMyc gene, when expressed in Drosophila, impedes activated JNK signaling-induced cell death. Thus, besides its well-studied apoptosis promoting function, Myc also antagonizes JNK-mediated cell death in Drosophila, and this function is likely conserved from fly to human.

  17. A familial ATP13A2 mutation enhances alpha-synuclein aggregation and promotes cell death.

    PubMed

    Lopes da Fonseca, Tomás; Pinho, Raquel; Outeiro, Tiago F

    2016-07-15

    Aberrant protein-protein interactions are a common pathological hallmark among neurodegenerative diseases, including Parkinson's disease (PD). Thus far, mutations in more than 20 genes have been associated with PD. These genes encode for proteins involved in distinct intracellular pathways, complicating our understanding of the precise molecular mechanisms underlying the disease. Recent reports suggested that the endolysosomal protein ATP13A2 can determine the fate of alpha-synuclein (α-Syn), although no consensus has yet been reached on the mechanisms underlying this effect. Here, we describe, for the first time, the deleterious effect arising from the interaction between the ATP13A2 familial mutant Dup22 with α-Syn. We show that this ATP13A2 mutant can enhance α-Syn oligomerization and aggregation in cell culture. Additionally, we report the accumulation of both proteins in abnormal endoplasmic reticulum membranous structures and the activation of the protein kinase RNA-like endoplasmic reticulum kinase pathway. Ultimately, our data bring new insight into the molecular mechanisms underlying the interplay of these two proteins, opening novel perspectives for therapeutic intervention.

  18. Pathogen-induced SGT1 of Arachis diogoi induces cell death and enhanced disease resistance in tobacco and peanut.

    PubMed

    Kumar, Dilip; Kirti, Pulugurtha Bharadwaja

    2015-01-01

    We have identified a transcript derived fragment (TDF) corresponding to SGT1 in a study of differential gene expression on the resistant wild peanut, Arachis diogoi, upon challenge from the late leaf spot pathogen, Phaeoisariopsis personata, and cloned its full-length cDNA followed by subsequent validation through q-PCR. Sodium nitroprusside, salicylic acid, ethephon and methyl jasmonate induced the expression of AdSGT1, while the treatment with abscisic acid did not elicit its up-regulation. AdSGT1 is localized to both nucleus and cytoplasm. Its overexpression induced hypersensitive-like cell death in tobacco under transient conditional expression using the estradiol system, and this conditional expression of AdSGT1 was also associated with the up-regulation of NtHSR203J, HMGR and HIN1, which have been shown to be associated with hypersensitive response in tobacco in earlier studies. Expression of the cDNA in a susceptible cultivated peanut variety enhanced its resistance against the late leaf spot pathogen, Phaeoisariopsis personata, while the heterologous expression in tobacco enhanced its resistance against Phytophthora parasitica var. nicotianae, Alternaria alternata var. nicotianae and Rhizoctonia solani. Constitutive expression in peanut was associated with the co-expression of resistance-related genes, CC-NB-LRR and some protein kinases.

  19. Dragon enhances BMP signaling and increases transepithelial resistance in kidney epithelial cells.

    PubMed

    Xia, Yin; Babitt, Jodie L; Bouley, Richard; Zhang, Ying; Da Silva, Nicolas; Chen, Shanzhuo; Zhuang, Zhenjie; Samad, Tarek A; Brenner, Gary J; Anderson, Jennifer L; Hong, Charles C; Schneyer, Alan L; Brown, Dennis; Lin, Herbert Y

    2010-04-01

    The neuronal adhesion protein Dragon acts as a bone morphogenetic protein (BMP) coreceptor that enhances BMP signaling. Given the importance of BMP signaling in nephrogenesis and its putative role in the response to injury in the adult kidney, we studied the localization and function of Dragon in the kidney. We observed that Dragon localized predominantly to the apical surfaces of tubular epithelial cells in the thick ascending limbs, distal convoluted tubules, and collecting ducts of mice. Dragon expression was weak in the proximal tubules and glomeruli. In mouse inner medullary collecting duct (mIMCD3) cells, Dragon generated BMP signals in a ligand-dependent manner, and BMP4 is the predominant endogenous ligand for the Dragon coreceptor. In mIMCD3 cells, BMP4 normally signaled through BMPRII, but Dragon enhanced its signaling through the BMP type II receptor ActRIIA. Dragon and BMP4 increased transepithelial resistance (TER) through the Smad1/5/8 pathway. In epithelial cells isolated from the proximal tubule and intercalated cells of collecting ducts, we observed coexpression of ActRIIA, Dragon, and BMP4 but not BMPRII. Taken together, these results suggest that Dragon may enhance BMP signaling in renal tubular epithelial cells and maintain normal renal physiology.

  20. Enhanced FCGR2A and FCGR3A signaling by HIV viremic controller IgG

    PubMed Central

    Alvarez, Raymond A.; Maestre, Ana M.; Durham, Natasha D.; Barria, Maria Ines; Ishii-Watabe, Akiko; Tada, Minoru; Hotta, Mathew T.; Rodriguez-Caprio, Gabriela; Fierer, Daniel S.; Fernandez-Sesma, Ana; Simon, Viviana; Chen, Benjamin K.

    2017-01-01

    HIV-1 viremic controllers (VC) spontaneously control infection without antiretroviral treatment. Several studies indicate that IgG Abs from VCs induce enhanced responses from immune effector cells. Since signaling through Fc-γ receptors (FCGRs) modulate these Ab-driven responses, here we examine if enhanced FCGR activation is a common feature of IgG from VCs. Using an infected cell–based system, we observed that VC IgG stimulated greater FCGR2A and FCGR3A activation as compared with noncontrollers, independent of the magnitude of HIV-specific Ab binding or virus neutralization activities. Multivariate regression analysis showed that enhanced FCGR signaling was a significant predictor of VC status as compared with chronically infected patients (CIP) on highly active antiretroviral therapy (HAART). Unsupervised hierarchical clustering of patient IgG functions primarily grouped VC IgG profiles by enhanced FCGR2A, FCGR3A, or dual signaling activity. Our findings demonstrate that enhanced FCGR signaling is a common and significant predictive feature of VC IgG, with VCs displaying a distinct spectrum of FCGR activation profiles. Thus, profiling FCGR activation may provide a useful method for screening and distinguishing protective anti-HIV IgG responses in HIV-infected patients and in monitoring HIV vaccination regimens. PMID:28239647

  1. Synergistic enhancement of breast cancer cell death using ultrasound-microbubbles in combination with cisplatin

    NASA Astrophysics Data System (ADS)

    Jetha, Sheliza; Karshafian, Raffi

    2017-03-01

    .0001) based on Bliss Independence model with a 95% confidence interval of p<0.05 after 48-hour incubation. The combination of ultrasound-microbubble and cisplatin synergistically enhances chemotherapeutic effectiveness in breast cancer cells. However, this enhanced effectiveness, in breast cancer cells (MDA-MB-231), is dependent on incubation time and cisplatin (CDDP) concentration.

  2. Ultra-violet B (UVB)-induced skin cell death occurs through a cyclophilin D intrinsic signaling pathway

    SciTech Connect

    Ji, Chao; Yang, Bo; Yang, Zhi; Tu, Ying; Yang, Yan-li; He, Li; Bi, Zhi-Gang

    2012-09-07

    Highlights: Black-Right-Pointing-Pointer UVB radiated skin keratinocytes show cyclophilin D (Cyp-D) upregulation. Black-Right-Pointing-Pointer NAC inhibits UVB induced Cyp-D expression, while H{sub 2}O{sub 2} facilitates it. Black-Right-Pointing-Pointer Cyp-D-deficient cells are significantly less susceptible to UVB induced cell death. Black-Right-Pointing-Pointer Over-expression of Cyp-D causes spontaneous keratinocytes cell death. -- Abstract: UVB-induced skin cell damage involves the opening of mitochondrial permeability transition pore (mPTP), which leads to both apoptotic and necrotic cell death. Cyclophilin D (Cyp-D) translocation to the inner membrane of mitochondrion acts as a key component to open the mPTP. Our Western-Blot results in primary cultured human skin keratinocytes and in HaCaT cell line demonstrated that UVB radiation and hydrogen peroxide (H{sub 2}O{sub 2}) induced Cyp-D expression, which was inhibited by anti-oxidant N-acetyl cysteine (NAC). We created a stable Cyp-D deficiency skin keratinocytes by expressing Cyp-D-shRNA through lentiviral infection. Cyp-D-deficient cells were significantly less susceptible than their counterparts to UVB- or H{sub 2}O{sub 2}-induced cell death. Further, cyclosporine A (Cs-A), a Cyp-D inhibitor, inhibited UVB- or H{sub 2}O{sub 2}-induced keratinocytes cell death. Reversely, over-expression of Cyp-D in primary keratinocytes caused spontaneous keratinocytes cell death. These results suggest Cyp-D's critical role in UVB/oxidative stress-induced skin cell death.

  3. Equalization-enhanced phase noise for coherent-detection systems using electronic digital signal processing.

    PubMed

    Shieh, William; Ho, Keang-Po

    2008-09-29

    In coherent optical systems employing electronic digital signal processing, the fiber chromatic dispersion can be gracefully compensated in electronic domain without resorting to optical techniques. Unlike optical dispersion compensator, the electronic equalizer enhances the impairments from the laser phase noise. This equalization-enhanced phase noise (EEPN) imposes a tighter constraint on the receive laser phase noise for transmission systems with high symbol rate and large electronically-compensated chromatic dispersion.

  4. NMR signal enhancement of >50 000 times in fast dissolution dynamic nuclear polarization.

    PubMed

    Pinto, L F; Marín-Montesinos, I; Lloveras, V; Muñoz-Gómez, J L; Pons, M; Veciana, J; Vidal-Gancedo, J

    2017-03-17

    Herein, we report the synthesis and the study of a novel mixed biradical with BDPA and TEMPO radical units that are covalently bound by an ester group (BDPAesterTEMPO) as a polarizing agent for fast dissolution DNP. The biradical exhibits an extremely high DNP NMR enhancement of >50 000 times, which constitutes one of the largest signal enhancements observed so far, to the best of our knowledge.

  5. Model-based speech enhancement using a bone-conducted signal.

    PubMed

    Kechichian, Patrick; Srinivasan, Sriram

    2012-03-01

    Codebook-based single-microphone noise suppressors, which exploit prior knowledge about speech and noise statistics, provide better performance in nonstationary noise. However, as the enhancement involves a joint optimization over speech and noise codebooks, this results in high computational complexity. A codebook-based method is proposed that uses a reference signal observed by a bone-conduction microphone, and a mapping between air- and bone-conduction codebook entries generated during an offline training phase. A smaller subset of air-conducted speech codebook entries that accurately models the clean speech signal is selected using this reference signal. Experiments support the expected improvement in performance at low computational complexity.

  6. A High Soy Diet Reduces Programmed Cell Death and Enhances Bcl-xL Expression In Experimental Stroke

    PubMed Central

    Lovekamp-Swan, Tara; Glendenning, Michele; Schreihofer, Derek A.

    2009-01-01

    Soy phytoestrogens have been proposed as an alternative to estrogen replacement therapy and have demonstrated potential neuroprotective effects in the brain. We have shown that a high soy diet significantly reduces infarct size following permanent middle cerebral artery occlusion (MCAO). Here, we tested the hypothesis that a high soy diet would attenuate programmed cell death after stroke. Adult female Sprague-Dawley rats were ovariectomized and fed either an isoflavone-reduced diet (IFP) or a high soy diet (SP) for 2 weeks before undergoing 90 minutes of transient MCAO (tMCAO) followed by 22.5 hr reperfusion. Infarct size, as assessed by TTC staining, was significantly reduced by a high soy diet (p< 0.05). Apoptosis in the ischemic cortex, measured by TUNEL staining, was significantly reduced by the high soy diet. The number of active caspase-3 positive cells and caspase-mediated α-spectrin cleavage was also significantly decreased in the ischemic cortex of SP rats. Furthermore, nuclear translocation of apoptosis-inducing factor (AIF) was significantly reduced in the ischemic cortex of SP rats. Soy significantly increased bcl-xL mRNA and protein expression in the ischemic cortex compared to IFP rats. Immunohistochemistry revealed increased neuronal expression of bcl-2 and bcl-xL in the ischemic cortex of both IFP and SP rats following tMCAO. These results suggest that a high soy diet decreases both caspase-dependent and caspase-independent programmed cell death following tMCAO. Further, a high soy diet enhances expression of the cell survival factor bcl-xL following tMCAO, contributing to the neuroprotective effects of soy in the ischemic cortex. PMID:17706879

  7. ENHANCED DISEASE SUSCEPTIBILITY 1 and SALICYLIC ACID act redundantly to regulate resistance gene-mediated signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resistance (R) protein–associated pathways are well known to participate in defense against a variety of microbial pathogens. Salicylic acid (SA) and its associated proteinaceous signaling components, including enhanced disease susceptibility 1 (EDS1), non–race-specific disease resistance 1 (NDR1), ...

  8. Laser Induced Breakdown Spectroscopy Based on Single Beam Splitting and Geometric Configuration for Effective Signal Enhancement

    PubMed Central

    Yang, Guang; Lin, Qingyu; Ding, Yu; Tian, Di; Duan, Yixiang

    2015-01-01

    A new laser induced breakdown spectroscopy (LIBS) based on single-beam-splitting (SBS) and proper optical geometric configuration has been initially explored in this work for effective signal enhancement. In order to improve the interaction efficiency of laser energy with the ablated material, a laser beam operated in pulse mode was divided into two streams to ablate/excite the target sample in different directions instead of the conventional one beam excitation in single pulse LIBS (SP-LIBS). In spatial configuration, the laser beam geometry plays an important role in the emission signal enhancement. Thus, an adjustable geometric configuration with variable incident angle between the two splitted laser beams was constructed for achieving maximum signal enhancement. With the optimized angles of 60° and 70° for Al and Cu atomic emission lines at 396.15 nm and 324.75 nm respectively, about 5.6- and 4.8-folds signal enhancements were achieved for aluminum alloy and copper alloy samples compared to SP-LIBS. Furthermore, the temporal analysis, in which the intensity of atomic lines in SP-LIBS decayed at least ten times faster than the SBS-LIBS, proved that the energy coupling efficiency of SBS-LIBS was significantly higher than that of SP-LIBS. PMID:25557721

  9. Modulation of notch signaling pathway to prevent H2O2/menadione-induced SK-N-MC cells death by EUK134.

    PubMed

    Kamarehei, Maryam; Yazdanparast, Razieh

    2014-10-01

    The brain in Alzheimer's disease is under increased oxidative stress, and this may have a role in the pathogenesis and neural death in this disorder. It has been verified that numerous signaling pathways involved in neurodegenerative disorders are activated in response to reactive oxygen species (ROS). EUK134, a synthetic salen-manganese antioxidant complex, has been found to possess many interesting pharmacological activities awaiting exploration. The present study is to characterize the role of Notch signaling in apoptotic cell death of SK-N-MC cells. The cells were treated with hydrogen peroxide (H2O2) or menadione to induce oxidative stress. The free-radical scavenging capabilities of EUK134 were studied through the MTT assay, glutathione peroxidase (GPx) enzyme activity assay, and glutathione (GSH) Levels. The extents of lipid peroxidation, protein carbonyl formation, and intracellular ROS levels, as markers of oxidative stress, were also studied. Our results showed that H2O2/menadione reduced GSH levels and GPx activity. However, EUK134 protected cells against ROS-induced cell death by down-regulation of lipid peroxidation and protein carbonyl formation as well as restoration of antioxidant enzymes activity. ROS induced apoptosis and increased NICD and HES1 expression. Inhibition of NICD production proved that Notch signaling is involved in apoptosis through p53 activation. Moreover, H2O2/menadione led to Numb protein down-regulation which upon EUK134 pretreatment, its level increased and subsequently prevented Notch pathway activation. We indicated that EUK134 can be a promising candidate in designing natural-based drugs for ROS-induced neurodegenerative diseases. Collectively, ROS activated Notch signaling in SK-N-MC cells leading to cell apoptosis.

  10. Raman signal enhancement by multiple beam excitation and its application for the detection of chemicals

    SciTech Connect

    Gupta, Sakshi; Ahmad, Azeem; Mehta, Dalip S.; Gambhir, Vijayeta; Reddy, Martha N.

    2015-08-31

    In a typical Raman based sensor, a single laser beam is used for exciting the sample and the backscattered or forward scattered light is collected using collection optics and is analyzed by a spectrometer. We have investigated that by means of exciting the sample with multiple beams, i.e., by dividing the same input power of the single beam into two or three or more beams and exciting the sample from different angles, the Raman signal enhances significantly. Due to the presence of multiple beams passing through the same volume of the sample, an interference pattern is formed and the volume of interaction of excitation beams with the sample increases. By means of this geometry, the enhancement in the Raman signal is observed and it was found that the signal strength increases linearly with the increase in number of excitation beams. Experimental results of this scheme for excitation of the samples are reported for explosive detection at a standoff distance.

  11. Enhanced brain signal variability in children with autism spectrum disorder during early childhood.

    PubMed

    Takahashi, Tetsuya; Yoshimura, Yuko; Hiraishi, Hirotoshi; Hasegawa, Chiaki; Munesue, Toshio; Higashida, Haruhiro; Minabe, Yoshio; Kikuchi, Mitsuru

    2016-03-01

    Extensive evidence shows that a core neurobiological mechanism of autism spectrum disorder (ASD) involves aberrant neural connectivity. Recent advances in the investigation of brain signal variability have yielded important information about neural network mechanisms. That information has been applied fruitfully to the assessment of aging and mental disorders. Multiscale entropy (MSE) analysis can characterize the complexity inherent in brain signal dynamics over multiple temporal scales in the dynamics of neural networks. For this investigation, we sought to characterize the magnetoencephalography (MEG) signal variability during free watching of videos without sound using MSE in 43 children with ASD and 72 typically developing controls (TD), emphasizing early childhood to older childhood: a critical period of neural network maturation. Results revealed an age-related increase of brain signal variability in a specific timescale in TD children, whereas atypical age-related alteration was observed in the ASD group. Additionally, enhanced brain signal variability was observed in children with ASD, and was confirmed particularly for younger children. In the ASD group, symptom severity was associated region-specifically and timescale-specifically with reduced brain signal variability. These results agree well with a recently reported theory of increased brain signal variability during development and aberrant neural connectivity in ASD, especially during early childhood. Results of this study suggest that MSE analytic method might serve as a useful approach for characterizing neurophysiological mechanisms of typical-developing and its alterations in ASD through the detection of MEG signal variability at multiple timescales.

  12. Spatial extent of plasmonic enhancement of vibrational signals in the infrared.

    PubMed

    Neubrech, Frank; Beck, Sebastian; Glaser, Tobias; Hentschel, Mario; Giessen, Harald; Pucci, Annemarie

    2014-06-24

    Infrared vibrations of molecular species can be enhanced by several orders of magnitude with plasmonic nanoantennas. Based on the confined electromagnetic near-fields of resonantly excited metal nanoparticles, this antenna-assisted surface-enhanced infrared spectroscopy enables the detection of minute amounts of analytes localized in the nanometer-scale vicinity of the structure. Among other important parameters, the distance of the vibrational oscillator of the analyte to the nanoantenna surface determines the signal enhancement. For sensing applications, this is a particularly important issue since the vibrating dipoles of interest may be located far away from the antenna surface because of functional layers and the large size of biomolecules, proteins, or bacteria. The relation between distance and signal enhancement is thus of paramount importance and measured here with in situ infrared spectroscopy during the growth of a probe layer. Our results indicate a diminishing signal enhancement and the effective saturation of the plasmonic resonance shift beyond 100 nm. The experiments carried out under ultra-high-vacuum conditions are supported by numerical calculations.

  13. Ceramide, sphingoid bases, and sphingoid base metabolites as lipid mediators in signaling pathways leading to cell death and disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased ceramide generation de novo is known to be involved in the mechanism of action of many chemotherapeutic agents and conditions which disrupt cell cycle progression and induce cell death. Conversely, the metabolism of ceramide to sphingoid bases and and sphingoid base 1-phosphates has been i...

  14. Acetylated Chitosan Oligosaccharides Act as Antagonists against Glutamate-Induced PC12 Cell Death via Bcl-2/Bax Signal Pathway

    PubMed Central

    Hao, Cui; Gao, Lixia; Zhang, Yiran; Wang, Wei; Yu, Guangli; Guan, Huashi; Zhang, Lijuan; Li, Chunxia

    2015-01-01

    Chitosan oligosaccharides (COSs), depolymerized products of chitosan composed of β-(1→4) d-glucosamine units, have broad range of biological activities such as antitumour, antifungal, and antioxidant activities. In this study, peracetylated chitosan oligosaccharides (PACOs) and N-acetylated chitosan oligosaccharides (NACOs) were prepared from the COSs by chemcal modification. The structures of these monomers were identified using NMR and ESI-MS spectra. Their antagonist effects against glutamate-induced PC12 cell death were investigated. The results showed that pretreatment of PC12 cells with the PACOs markedly inhibited glutamate-induced cell death in a concentration-dependent manner. The PACOs were better glutamate antagonists compared to the COSs and the NACOs, suggesting the peracetylation is essential for the neuroprotective effects of chitosan oligosaccharides. In addition, the PACOs pretreatment significantly reduced lactate dehydrogenase release and reactive oxygen species production. It also attenuated the loss of mitochondrial membrane potential. Further studies indicated that the PACOs inhibited glutamate-induced cell death by preventing apoptosis through depressing the elevation of Bax/Bcl-2 ratio and caspase-3 activation. These results suggest that PACOs might be promising antagonists against glutamate-induced neural cell death. PMID:25775423

  15. Neonatal Death

    MedlinePlus

    ... Home > Complications & Loss > Loss & grief > Neonatal death Neonatal death E-mail to a friend Please fill in ... cope with your baby’s death. What is neonatal death? Neonatal death is when a baby dies in ...

  16. Label-free electrochemical lead (II) aptasensor using thionine as the signaling molecule and graphene as signal-enhancing platform.

    PubMed

    Gao, Feng; Gao, Cai; He, Suyu; Wang, Qingxiang; Wu, Aiqun

    2016-07-15

    A label-free and highly sensitive electrochemical aptasensor for Pb(2+) was constructed using thionine (TH) as the signaling molecule and graphene (GR) as the signal-enhancing platform. The electrochemical sensing interface was fabricated by stepwise assembly of GR and TH on the lead (II) specific aptamer (LSA) modified electrode. Upon interaction with Pb(2+), the aptamer probe on the sensor underwent conformational switch from a single-stranded DNA form to the G-quadruplex structure, causing the GR with assembled TH released from the electrode surface into solution. As a result, the electrochemical signal of TH on the aptasensor was substantially reduced. Under the optimal experimental conditions, the attenuation of peak currents presented a good linear relationship with the logarithm of Pb(2+) concentrations over the range from 1.6×10(-13) to 1.6×10(-10)M. The detection limit was estimated to be 3.2×10(-14)M. The aptasensor also exhibited good regenerability, excellent selectivity, and acceptable reproducibility, indicating promising application in environment monitoring of lead.

  17. Lupeol, a fruit and vegetable based triterpene, induces apoptotic death of human pancreatic adenocarcinoma cells via inhibition of Ras signaling pathway.

    PubMed

    Saleem, Mohammad; Kaur, Satwinderjeet; Kweon, Mee-Hyang; Adhami, Vaqar Mustafa; Afaq, Farrukh; Mukhtar, Hasan

    2005-11-01

    Pancreatic cancer is an exceptionally aggressive disease, the treatment of which has largely been unsuccessful due to higher resistance offered by pancreatic cancer cells to conventional approaches such as surgery, radiation and/or chemotherapy. The aberration of Ras oncoprotein has been linked to the induction of multiple signaling pathways and to the resistance offered by pancreatic cancer cells to apoptosis. Therefore, there is a need for development of new and effective chemotherapeutic agents which can target multiple pathways to induce responsiveness of pancreatic cancer cells to death signals. In this study, human pancreatic adenocarcinoma cells AsPC-1 were used to investigate the effect of Lupeol on cell growth and its effects on the modulation of multiple Ras-induced signaling pathways. Lupeol caused a dose-dependent inhibition of cell growth as assessed by MTT assay and induction of apoptosis as assessed by flow cytometry, fluorescence microscopy and western blotting. Lupeol treatment to cells was found to significantly reduce the expression of Ras oncoprotein and modulate the protein expression of various signaling molecules involved in PKCalpha/ODC, PI3K/Akt and MAPKs pathways along with a significant reduction in the activation of NFkappaB signaling pathway. Our data suggest that Lupeol can adopt a multi-prong strategy to target multiple signaling pathways leading to induction of apoptosis and inhibition of growth of pancreatic cancer cells. Lupeol could be a potential agent against pancreatic cancer, however, further in-depth in vivo studies are warranted.

  18. Identification of Fusarium virguliforme FvTox1-Interacting Synthetic Peptides for Enhancing Foliar Sudden Death Syndrome Resistance in Soybean

    PubMed Central

    Wang, Bing; Swaminathan, Sivakumar; Bhattacharyya, Madan K.

    2015-01-01

    Soybean is one of the most important crops grown across the globe. In the United States, approximately 15% of the soybean yield is suppressed due to various pathogen and pests attack. Sudden death syndrome (SDS) is an emerging fungal disease caused by Fusarium virguliforme. Although growing SDS resistant soybean cultivars has been the main method of controlling this disease, SDS resistance is partial and controlled by a large number of quantitative trait loci (QTL). A proteinacious toxin, FvTox1, produced by the pathogen, causes foliar SDS. Earlier, we demonstrated that expression of an anti-FvTox1 single chain variable fragment antibody resulted in reduced foliar SDS development in transgenic soybean plants. Here, we investigated if synthetic FvTox1-interacting peptides, displayed on M13 phage particles, can be identified for enhancing foliar SDS resistance in soybean. We screened three phage-display peptide libraries and discovered four classes of M13 phage clones displaying FvTox1-interacting peptides. In vitro pull-down assays and in vivo interaction assays in yeast were conducted to confirm the interaction of FvTox1 with these four synthetic peptides and their fusion-combinations. One of these peptides was able to partially neutralize the toxic effect of FvTox1 in vitro. Possible application of the synthetic peptides in engineering SDS resistance soybean cultivars is discussed. PMID:26709700

  19. Method of Enhancing On-Board State Estimation Using Communication Signals

    NASA Technical Reports Server (NTRS)

    Anzalone, Evan J. (Inventor); Chuang, Jason C. H. (Inventor)

    2015-01-01

    A method of enhancing on-board state estimation for a spacecraft utilizes a network of assets to include planetary-based assets and space-based assets. Communication signals transmitted from each of the assets into space are defined by a common protocol. Data is embedded in each communication signal transmitted by the assets. The data includes a time-of-transmission for a corresponding one of the communication signals and a position of a corresponding one of the assets at the time-of-transmission. A spacecraft is equipped to receive the communication signals, has a clock synchronized to the space-wide time reference frame, and has a processor programmed to generate state estimates of the spacecraft. Using its processor, the spacecraft determines a one-dimensional range from itself to at least one of the assets and then updates its state estimates using each one-dimensional range.

  20. Infection-induced viscerosensory signals from the gut enhance anxiety: implications for psychoneuroimmunology.

    PubMed

    Goehler, Lisa E; Lyte, Mark; Gaykema, Ronald P A

    2007-08-01

    Infection and inflammation lead to changes in mood and cognition. Although the "classic" sickness behavior syndrome, involving fatigue, social withdrawal, and loss of appetites are most familiar, other emotional responses accompany immune activation, including anxiety. Recent studies have shown that gastrointestinal bacterial infections lead to enhanced anxiety-like behavior in mice. The bacteria-induced signal is most likely carried by vagal sensory neurons, and occurs early on (within 6h) during the infection. These signals induce evidence of activation in brain regions that integrate viscerosensory information with mood, and potentiate activation in brain regions established as key players in fear and anxiety. The findings underline the importance of viscerosensory signals arising from the gastrointestinal tract in modulation of behaviors appropriate for coping with threats, and suggest that these signals may contribute to affective symptoms associated with gastrointestinal disorders.

  1. Characterisation of signal enhancements achieved when utilizing a photon diode in deep Raman spectroscopy of tissue

    PubMed Central

    Vardaki, Martha Z.; Matousek, Pavel; Stone, Nicholas

    2016-01-01

    We characterise the performance of a beam enhancing element (‘photon diode’) for use in deep Raman spectroscopy (DRS) of biological tissues. The optical component enhances the number of laser photons coupled into a tissue sample by returning escaping photons back into it at the illumination zone. The method is compatible with transmission Raman spectroscopy, a deep Raman spectroscopy concept, and its implementation leads to considerable enhancement of detected Raman photon rates. In the past, the enhancement concept was demonstrated with a variety of samples (pharmaceutical tablets, tissue, etc) but it was not systematically characterized with biological tissues. In this study, we investigate the enhancing properties of the photon diode in the transmission Raman geometry as a function of: a) the depth and b) the optical properties of tissue samples. Liquid tissue phantoms were employed to facilitate systematic variation of optical properties. These were chosen to mimic optical properties of human tissues, including breast and prostate. The obtained results evidence that a photon diode can enhance Raman signals of tissues by a maximum of × 2.4, although it can also decrease the signals created towards the back of samples that exhibit high scattering or absorption properties. PMID:27375932

  2. Transmembrane TNF-α mediates “forward” and “reverse” signaling, inducing cell death or survival via the NF-κB pathway in Raji Burkitt lymphoma cells

    PubMed Central

    Zhang, Hailong; Yan, Dan; Shi, Xu; Liang, Huifang; Pang, Yan; Qin, Nalin; Chen, Hui; Wang, Jing; Yin, Bingjiao; Jiang, Xiaodan; Feng, Wei; Zhang, Wenjie; Zhou, Muxiang; Li, Zhuoya

    2008-01-01

    Interestingly, some lymphoma cells, expressing high levels of transmembrane (tm)TNF-α, are resistant to secretory (s)TNF-α-induced necrosis but sensitive to tmTNF-α-mediated apoptosis. As tmTNF-α mediates “forward” as well as “reverse” signaling, we hypothesize that a balanced signaling between forward and reverse directions may play a critical role in determining the fate of cells bearing tmTNF-α. Using Raji cells as a model, we first added exogenous tmTNF-α on fixed, transfected NIH3T3 cells onto Raji cells to examine tmTNF-α forward signaling and its effects, showing that constitutive NF-κB activity and cellular inhibitor-of-apoptosis protein 1 transcription were down-regulated, paralleled with Raji cell death. As Raji cells express tmTNF-α, an inhibition of their tmTNF-α expression by antisense oligonucleotide caused down-regulation of NF-κB activity. Conversely, increasing tmTNF-α expression by suppressing expression of TNF-α-converting enzyme that cleaves tmTNF-α led to an enhanced activation of NF-κB, indicating that tmTNF-α, but not sTNF-α, contributes to constitutive NF-κB activation. We next transfected Raji cells with a mutant tmTNF-α lacking the intracellular domain to competitively suppress reverse signaling via tmTNF-α; as expected, constitutive NF-κB activity was decreased. In contrast, treating Raji cells with sTNFR2 to stimulate reverse signaling via tmTNF-α ehanced NF-κB activation. We conclude that tmTNF-α, when highly expressed on tumor cells and acting as a receptor, promotes NF-κB activation through reverse signaling, which is helpful to maintain tumor cell survival. On the contrary, tmTNF-α, when acting as a ligand, inhibits NF-κB activity through forward signaling, which is inclined to induce tumor cell death. PMID:18550789

  3. Producing >60,000-fold room-temperature 89Y NMR signal enhancement

    NASA Astrophysics Data System (ADS)

    Lumata, Lloyd; Jindal, Ashish; Merritt, Matthew; Malloy, Craig; Sherry, A. Dean; Kovacs, Zoltan

    2011-03-01

    89 Y in chelated form is potentially valuable in medical imaging because its chemical shift is sensitive to local factors in tumors such as pH. However, 89 Y has a low gyromagnetic ratio γn thus its NMR signal is hampered by low thermal polarization. Here we show that we can enhance the room-temperature NMR signal of 89 Y up to 65,000 times the thermal signal, which corresponds to 10 % nuclear polarization, via fast dissolution dynamic nuclear polarization (DNP). The relatively long spin-lattice relaxation time T1 (~ 500 s) of 89 Y translates to a long polarization lifetime. The 89 Y NMR enhancement is optimized by varying the glassing matrices and paramagnetic agents as well as doping the samples with a gadolinium relaxation agent. Co-polarization of 89 Y-DOTA with a 13 C sample shows that both nuclear spin species acquire the same spin temperature Ts , consistent with thermal mixing mechanism of DNP. The high room-temperature NMR signal enhancement places 89 Y, one of the most challenging nuclei to detect by NMR, in the list of viable magnetic resonance imaging (MRI) agents when hyperpolarized under optimized conditions. This work is supported in part by the National Institutes of Health grant numbers 1R21EB009147-01 and RR02584.

  4. Tcra enhancer activation by inducible transcription factors downstream of pre-TCR signaling.

    PubMed

    del Blanco, Beatriz; García-Mariscal, Alberto; Wiest, David L; Hernández-Munain, Cristina

    2012-04-01

    The Tcra enhancer (Eα) is essential for pre-TCR-mediated activation of germline transcription and V(D)J recombination. Eα is considered an archetypical enhanceosome that acts through the functional synergy and cooperative binding of multiple transcription factors. Based on dimethylsulfate genomic footprinting experiments, there has been a long-standing paradox regarding Eα activation in the absence of differences in enhancer occupancy. Our data provide the molecular mechanism of Eα activation and an explanation of this paradox. We found that germline transcriptional activation of Tcra is dependent on constant phospholipase Cγ, as well as calcineurin- and MAPK/ERK-mediated signaling, indicating that inducible transcription factors are crucially involved. NFAT, AP-1, and early growth response factor 1, together with CREB-binding protein/p300 coactivators, bind to Eα as part of an active enhanceosome assembled during pre-TCR signaling. We favor a scenario in which the binding of lymphoid-restricted and constitutive transcription factors to Eα prior to its activation forms a regulatory scaffold to recruit factors induced by pre-TCR signaling. Thus, the combinatorial assembly of tissue- and signal-specific transcription factors dictates the Eα function. This mechanism for enhancer activation may represent a general paradigm in tissue-restricted and stimulus-responsive gene regulation.

  5. Visible light communications using predistortion signal to enhance the response of passive optical receiver

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Chen, Hung-Yu; Liang, Kevin; Wei, Liang-Yu; Chow, Chi-Wai; Yeh, Chien-Hung

    2016-01-01

    Traditional visible light communication (VLC) uses positive-intrinsic-negative photodiode (PD) or avalanche PD as the optical receivers (Rx). We demonstrate using a solar cell as the VLC Rx. The solar cell is flexible and low cost and converts the optical signal into an electrical signal directly without the need of external power supply. In addition to acting as the VLC passive Rx, the converted electrical signal from the solar cell can charge up the battery of the Rx nodes. Hence, the proposed scheme can be a promising candidate for the future Internet of Things network. However, a solar cell acting as a VLC Rx is very challenging, since the response of the solar cell is limited. Here, we propose and demonstrate using predistortion to significantly enhance the solar cell Rx response for the first time up to the authors' knowledge. Experimental results show that the response of the solar cell Rx is significantly enhanced; and the original 2-kHz detection bandwidth of the solar cell can be enhanced by 250 times for receiving 500-kbit/s VLC signal at a transmission distance of 1 m. The operation principle, the generated voltage by the solar cell, and the maximum data rates achieved at different transmission distances are also studied.

  6. Dealing with the problem of non-specific in situ mRNA hybridization signals associated with plant tissues undergoing programmed cell death

    PubMed Central

    2010-01-01

    Background In situ hybridization is a general molecular method typically used for the localization of mRNA transcripts in plants. The method provides a valuable tool to unravel the connection between gene expression and anatomy, especially in species such as pines which show large genome size and shortage of sequence information. Results In the present study, expression of the catalase gene (CAT) related to the scavenging of reactive oxygen species (ROS) and the polyamine metabolism related genes, diamine oxidase (DAO) and arginine decarboxylase (ADC), were localized in developing Scots pine (Pinus sylvestris L.) seeds. In addition to specific signals from target mRNAs, the probes continually hybridized non-specifically in the embryo surrounding region (ESR) of the megagametophyte tissue, in the remnants of the degenerated suspensors as well as in the cells of the nucellar layers, i.e. tissues exposed to cell death processes and extensive nucleic acid fragmentation during Scots pine seed development. Conclusions In plants, cell death is an integral part of both development and defence, and hence it is a common phenomenon in all stages of the life cycle. Our results suggest that extensive nucleic acid fragmentation during cell death processes can be a considerable source of non-specific signals in traditional in situ mRNA hybridization. Thus, the visualization of potential nucleic acid fragmentation simultaneously with the in situ mRNA hybridization assay may be necessary to ensure the correct interpretation of the signals in the case of non-specific hybridization of probes in plant tissues. PMID:20181098

  7. HTLV-1 bZIP factor enhances TGF-β signaling through p300 coactivator.

    PubMed

    Zhao, Tiejun; Satou, Yorifumi; Sugata, Kenji; Miyazato, Paola; Green, Patrick L; Imamura, Takeshi; Matsuoka, Masao

    2011-08-18

    Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic retrovirus that is etiologically associated with adult T-cell leukemia. The HTLV-1 bZIP factor (HBZ), which is encoded by the minus strand of the provirus, is involved in both regulation of viral gene transcription and T-cell proliferation. We showed in this report that HBZ interacted with Smad2/3, and enhanced transforming growth factor-β (TGF-β)/Smad transcriptional responses in a p300-dependent manner. The N-terminal LXXLL motif of HBZ was responsible for HBZ-mediated TGF-β signaling activation. In a serial immunoprecipitation assay, HBZ, Smad3, and p300 formed a ternary complex, and the association between Smad3 and p300 was markedly enhanced in the presence of HBZ. In addition, HBZ could overcome the repression of the TGF-β response by Tax. Finally, HBZ expression resulted in enhanced transcription of Pdgfb, Sox4, Ctgf, Foxp3, Runx1, and Tsc22d1 genes and suppression of the Id2 gene; such effects were similar to those by TGF-β. In particular, HBZ induced Foxp3 expression in naive T cells through Smad3-dependent TGF-β signaling. Our results suggest that HBZ, by enhancing TGF-β signaling and Foxp3 expression, enables HTLV-1 to convert infected T cells into regulatory T cells, which is thought to be a critical strategy for virus persistence.

  8. Dopamine D2-receptor blockade enhances decoding of prefrontal signals in humans.

    PubMed

    Kahnt, Thorsten; Weber, Susanna C; Haker, Helene; Robbins, Trevor W; Tobler, Philippe N

    2015-03-04

    The prefrontal cortex houses representations critical for ongoing and future behavior expressed in the form of patterns of neural activity. Dopamine has long been suggested to play a key role in the integrity of such representations, with D2-receptor activation rendering them flexible but weak. However, it is currently unknown whether and how D2-receptor activation affects prefrontal representations in humans. In the current study, we use dopamine receptor-specific pharmacology and multivoxel pattern-based functional magnetic resonance imaging to test the hypothesis that blocking D2-receptor activation enhances prefrontal representations. Human subjects performed a simple reward prediction task after double-blind and placebo controlled administration of the D2-receptor antagonist amisulpride. Using a whole-brain searchlight decoding approach we show that D2-receptor blockade enhances decoding of reward signals in the medial orbitofrontal cortex. Examination of activity patterns suggests that amisulpride increases the separation of activity patterns related to reward versus no reward. Moreover, consistent with the cortical distribution of D2 receptors, post hoc analyses showed enhanced decoding of motor signals in motor cortex, but not of visual signals in visual cortex. These results suggest that D2-receptor blockade enhances content-specific representations in frontal cortex, presumably by a dopamine-mediated increase in pattern separation. These findings are in line with a dual-state model of prefrontal dopamine, and provide new insights into the potential mechanism of action of dopaminergic drugs.

  9. Loss of C/EBPδ enhances IR-induced cell death by promoting oxidative stress and mitochondrial dysfunction.

    PubMed

    Banerjee, Sudip; Aykin-Burns, Nukhet; Krager, Kimberly J; Shah, Sumit K; Melnyk, Stepan B; Hauer-Jensen, Martin; Pawar, Snehalata A

    2016-10-01

    Exposure of cells to ionizing radiation (IR) generates reactive oxygen species (ROS). This results in increased oxidative stress and DNA double strand breaks (DSBs) which are the two underlying mechanisms by which IR causes cell/tissue injury. Cells that are deficient or impaired in the cellular antioxidant response are susceptible to IR-induced apoptosis. The transcription factor CCAAT enhancer binding protein delta (Cebpd, C/EBPδ) has been implicated in the regulation of oxidative stress, DNA damage response, genomic stability and inflammation. We previously reported that Cebpd-deficient mice are sensitive to IR and display intestinal and hematopoietic injury, however the underlying mechanism is not known. In this study, we investigated whether an impaired ability to detoxify IR-induced ROS was the underlying cause of the increased radiosensitivity of Cebpd-deficient cells. We found that Cebpd-knockout (KO) mouse embryonic fibroblasts (MEFs) expressed elevated levels of ROS, both at basal levels and after exposure to gamma radiation which correlated with increased apoptosis, and decreased clonogenic survival. Pre-treatment of wild type (WT) and KO MEFs with polyethylene glycol-conjugated Cu-Zn superoxide dismutase (PEG-SOD) and catalase (PEG-CAT) combination prior to irradiation showed a partial rescue of clonogenic survival, thus demonstrating a role for increased intracellular oxidants in promoting IR-induced cell death. Analysis of mitochondrial bioenergetics revealed that irradiated KO MEFs showed significant reductions in basal, adenosine triphosphate (ATP)-linked, maximal respiration and reserved respiratory capacity and decrease in intracellular ATP levels compared to WT MEFs indicating they display mitochondrial dysfunction. KO MEFs expressed significantly lower levels of the cellular antioxidant glutathione (GSH) and its precursor- cysteine as well as methionine. In addition to its antioxidant function, GSH plays an important role in detoxification of

  10. Advanced signal processing method for ground penetrating radar feature detection and enhancement

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Venkatachalam, Anbu Selvam; Huston, Dryver; Xia, Tian

    2014-03-01

    This paper focuses on new signal processing algorithms customized for an air coupled Ultra-Wideband (UWB) Ground Penetrating Radar (GPR) system targeting highway pavements and bridge deck inspections. The GPR hardware consists of a high-voltage pulse generator, a high speed 8 GSps real time data acquisition unit, and a customized field-programmable gate array (FPGA) control element. In comparison to most existing GPR system with low survey speeds, this system can survey at normal highway speed (60 mph) with a high horizontal resolution of up to 10 scans per centimeter. Due to the complexity and uncertainty of subsurface media, the GPR signal processing is important but challenging. In this GPR system, an adaptive GPR signal processing algorithm using Curvelet Transform, 2D high pass filtering and exponential scaling is proposed to alleviate noise and clutter while the subsurface features are preserved and enhanced. First, Curvelet Transform is used to remove the environmental and systematic noises while maintain the range resolution of the B-Scan image. Then, mathematical models for cylinder-shaped object and clutter are built. A two-dimension (2D) filter based on these models removes clutter and enhances the hyperbola feature in a B-Scan image. Finally, an exponential scaling method is applied to compensate the signal attenuation in subsurface materials and to improve the desired signal feature. For performance test and validation, rebar detection experiments and subsurface feature inspection in laboratory and field configurations are performed.

  11. AICAR enhances insulin signaling via downregulation of miR-29.

    PubMed

    Liu, Jia; Ye, Cheng; Liu, Wei; Zhao, Wei; Zhang, Ya-Jing; Zhang, Hong; Ying, Hao

    2015-08-12

    As an activator of AMPK, the effect of AICAR on insulin signaling has not been investigated extensively. PI3K-Akt is a critical node involved in the insulin signaling pathway. We observed that concomitant with the activation of AMPK by AICAR, the protein level of PI3K p85α and the insulin-induced phosphorylation of Akt were enhanced in mouse primary hepatocytes. Previously, we identified a group of AMPK-regulated miRNAs in hepatocytes. It is not clear whether miRNAs are related to the regulation of insulin signaling by AMPK. Here, we confirmed the negative regulation of miR-29 family members by AICAR treatment in mouse primary hepatocytes. Our results indicated that p85α is a direct target of miR-29 and is negatively regulated by miR-29b in hepatocytes. In agreement with the findings in vitro, we found that the expression of miR-29 and the protein levels of p85α were inversely correlated in the liver of fasted mice. Overexpression of miR-29b reduced the insulin-induced phosphorylation of Akt in hepatocytes, suggesting that miR-29 could serve as a negative regulator of insulin signaling. Furthermore, we found that overexpression of miR-29 could attenuate the effect of AICAR on p85α expression. Taken together, our results indicated that activation of AMPK may enhance insulin signaling via downregulation of miR-29.

  12. Dandelion root extract affects colorectal cancer proliferation and survival through the activation of multiple death signalling pathways.

    PubMed

    Ovadje, Pamela; Ammar, Saleem; Guerrero, Jose-Antonio; Arnason, John Thor; Pandey, Siyaram

    2016-11-08

    Dandelion extracts have been studied extensively in recent years for its anti-depressant and anti-inflammatory activity. Recent work from our lab, with in-vitro systems, shows the anti-cancer potential of an aqueous dandelion root extract (DRE) in several cancer cell models, with no toxicity to non-cancer cells. In this study, we examined the cancer cell-killing effectiveness of an aqueous DRE in colon cancer cell models. Aqueous DRE induced programmed cell death (PCD) selectively in > 95% of colon cancer cells, irrespective of their p53 status, by 48 hours of treatment. The anti-cancer efficacy of this extract was confirmed in in-vivo studies, as the oral administration of DRE retarded the growth of human colon xenograft models by more than 90%. We found the activation of multiple death pathways in cancer cells by DRE treatment, as revealed by gene expression analyses showing the expression of genes implicated in programmed cell death. Phytochemical analyses of the extract showed complex multi-component composition of the DRE, including some known bioactive phytochemicals such as α-amyrin, β-amyrin, lupeol and taraxasterol. This suggested that this natural extract could engage and effectively target multiple vulnerabilities of cancer cells. Therefore, DRE could be a non-toxic and effective anti-cancer alternative, instrumental for reducing the occurrence of cancer cells drug-resistance.

  13. Dandelion root extract affects colorectal cancer proliferation and survival through the activation of multiple death signalling pathways

    PubMed Central

    Ovadje, Pamela; Ammar, Saleem; Guerrero, Jose-Antonio; Arnason, John Thor; Pandey, Siyaram

    2016-01-01

    Dandelion extracts have been studied extensively in recent years for its anti-depressant and anti-inflammatory activity. Recent work from our lab, with in-vitro systems, shows the anti-cancer potential of an aqueous dandelion root extract (DRE) in several cancer cell models, with no toxicity to non-cancer cells. In this study, we examined the cancer cell-killing effectiveness of an aqueous DRE in colon cancer cell models. Aqueous DRE induced programmed cell death (PCD) selectively in > 95% of colon cancer cells, irrespective of their p53 status, by 48 hours of treatment. The anti-cancer efficacy of this extract was confirmed in in-vivo studies, as the oral administration of DRE retarded the growth of human colon xenograft models by more than 90%. We found the activation of multiple death pathways in cancer cells by DRE treatment, as revealed by gene expression analyses showing the expression of genes implicated in programmed cell death. Phytochemical analyses of the extract showed complex multi-component composition of the DRE, including some known bioactive phytochemicals such as α-amyrin, β-amyrin, lupeol and taraxasterol. This suggested that this natural extract could engage and effectively target multiple vulnerabilities of cancer cells. Therefore, DRE could be a non-toxic and effective anti-cancer alternative, instrumental for reducing the occurrence of cancer cells drug-resistance. PMID:27564258

  14. Genes and signaling pathways involved in memory enhancement in mutant mice

    PubMed Central

    2014-01-01

    Mutant mice have been used successfully as a tool for investigating the mechanisms of memory at multiple levels, from genes to behavior. In most cases, manipulating a gene expressed in the brain impairs cognitive functions such as memory and their underlying cellular mechanisms, including synaptic plasticity. However, a remarkable number of mutations have been shown to enhance memory in mice. Understanding how to improve a system provides valuable insights into how the system works under normal conditions, because this involves understanding what the crucial components are. Therefore, more can be learned about the basic mechanisms of memory by studying mutant mice with enhanced memory. This review will summarize the genes and signaling pathways that are altered in the mutants with enhanced memory, as well as their roles in synaptic plasticity. Finally, I will discuss how knowledge of memory-enhancing mechanisms could be used to develop treatments for cognitive disorders associated with impaired plasticity. PMID:24894914

  15. Genes and signaling pathways involved in memory enhancement in mutant mice.

    PubMed

    Lee, Yong-Seok

    2014-06-04

    Mutant mice have been used successfully as a tool for investigating the mechanisms of memory at multiple levels, from genes to behavior. In most cases, manipulating a gene expressed in the brain impairs cognitive functions such as memory and their underlying cellular mechanisms, including synaptic plasticity. However, a remarkable number of mutations have been shown to enhance memory in mice. Understanding how to improve a system provides valuable insights into how the system works under normal conditions, because this involves understanding what the crucial components are. Therefore, more can be learned about the basic mechanisms of memory by studying mutant mice with enhanced memory. This review will summarize the genes and signaling pathways that are altered in the mutants with enhanced memory, as well as their roles in synaptic plasticity. Finally, I will discuss how knowledge of memory-enhancing mechanisms could be used to develop treatments for cognitive disorders associated with impaired plasticity.

  16. Critical Performance Enhancement of Ultrahigh-Bandwidth Microwave Photonic Links through Nonlinear Photonic Signal Processing

    DTIC Science & Technology

    2013-04-11

    four-wave mixing (FWM) interaction such that in an amplifier-less link we are thermally noise limited after photodetection due to a low received...link with self-phase modulation based enhancement and balanced detection. optical signal. During this quarter we have constructed the sampling-based...photodetector. Furthermore, 8-dB of signal gain, a 3.6-dB improvement in OIP3, and a 3.1 -dB improvement in OIP2. the use of the balanced detector allows for

  17. Knockdown of TWIST1 enhances arsenic trioxide- and ionizing radiation-induced cell death in lung cancer cells by promoting mitochondrial dysfunction

    SciTech Connect

    Seo, Sung-Keum; Kim, Jae-Hee; Choi, Ha-Na; Choe, Tae-Boo; Hong, Seok-Il; Yi, Jae-Youn; Hwang, Sang-Gu; Lee, Hyun-Gyu; Lee, Yun-Han; Park, In-Chul

    2014-07-11

    Highlights: • Knockdown of TWIST1 enhanced ATO- and IR-induced cell death in NSCLCs. • Intracellular ROS levels were increased in cells treated with TWIST1 siRNA. • TWIST1 siRNA induced MMP loss and mitochondrial fragmentation. • TWIST1 siRNA upregulated the fission-related proteins FIS1 and DRP1. - Abstract: TWIST1 is implicated in the process of epithelial mesenchymal transition, metastasis, stemness, and drug resistance in cancer cells, and therefore is a potential target for cancer therapy. In the present study, we found that knockdown of TWIST1 by small interfering RNA (siRNA) enhanced arsenic trioxide (ATO)- and ionizing radiation (IR)-induced cell death in non-small-cell lung cancer cells. Interestingly, intracellular reactive oxygen species levels were increased in cells treated with TWIST1 siRNA and further increased by co-treatment with ATO or IR. Pretreatment of lung cancer cells with the antioxidant N-acetyl-cysteine markedly suppressed the cell death induced by combined treatment with TWIST1 siRNA and ATO or IR. Moreover, treatment of cells with TWIST1 siRNA induced mitochondrial membrane depolarization and significantly increased mitochondrial fragmentation (fission) and upregulated the fission-related proteins FIS1 and DRP1. Collectively, our results demonstrate that siRNA-mediated TWIST1 knockdown induces mitochondrial dysfunction and enhances IR- and ATO-induced cell death in lung cancer cells.

  18. Demonstration of composite signal enhancement from surface enhanced Raman spectroscopy in a liquid core optical ring resonator

    NASA Astrophysics Data System (ADS)

    White, Ian M.; Gohring, John; Fan, Xudong

    2007-09-01

    Surface enhanced Raman spectroscopy (SERS) utilizing silver colloids for localized plasmonic enhancement has been heavily researched due to its tremendous increase in the Raman signal of bio/chemical molecules. We demonstrate further enhancement by multiplying the SERS effect by the resonant enhancement of a ring resonator microcavity. The liquid core optical ring resonator (LCORR) offers a high-performance and practical design to obtain this composite enhancement for bio/chemical molecule detection. The LCORR integrates an array of optical ring resonators into a capillary-based microfluidic channel to form a novel bio/chemical sensing platform. The circular cross-section of the glass capillary acts as an optical ring resonator, with the evanescent field of the resonant light interacting with the sample passing through the capillary. The LCORR has already been well-studied for applications in label free biomolecule sensing. In this work, we utilize a silver colloid solution inside the capillary to perform SERS-based detection. In contrast to a typical SERS system where the incident light interacts with the colloid and target molecules only once, in the LCORR system, the tightly confined light resonates around the capillary wall, repeatedly interacting with the SERS system. Our experimental results show the increased enhancement due to the composite effect of the cavity resonance and the localized plasmonic effect of the nanoparticles inside the cavity. We have achieved detection of 3.3 nM R6G inside the LCORR. In addition to the excellent sensitivity, this detection system represents an advancement in the development of practical SERS bio/chemical sensors due to the arrayed nature of the sensors combined with the integrated microfluidics of the LCORR.

  19. Signal enhancement of surface enhanced Raman scattering and surface enhanced resonance Raman scattering using in situ colloidal synthesis in microfluidics.

    PubMed

    Wilson, Rab; Bowden, Stephen A; Parnell, John; Cooper, Jonathan M

    2010-03-01

    We demonstrate the enhanced analytical sensitivity of both surface enhanced Raman scattering (SERS) and surface enhanced resonance Raman scattering (SERRS) responses, resulting from the in situ synthesis of silver colloid in a microfluidic flow structure, where both mixing and optical interrogation were integrated on-chip. The chip-based sensor was characterized with a model Raman active label, rhodamine-6G (R6G), and had a limit of detection (LOD) of ca. 50 fM (equivalent to single molecule detection). The device was also used for the determination of the natural pigment, scytonemin, from cyanobacteria (as an analogue for extraterrestrial life existing in extreme environments). The observed LOD of approximately 10 pM (ca. <400 molecules) demonstrated the analytical advantages of working with freshly synthesized colloid in such a flow system. In both cases, sensitivities were between 1 and 2 orders of magnitude greater in the microfluidic system than those measured using the same experimental parameters, with colloid synthesized off-chip, under quiescent conditions.

  20. Induction of antigen-positive cell death by the expression of perforin, but not DTa, from a DNA vaccine enhances the immune response.

    PubMed

    Gargett, Tessa; Grubor-Bauk, Branka; Garrod, Tamsin J; Yu, Wenbo; Miller, Darren; Major, Lee; Wesselingh, Steve; Suhrbier, Andreas; Gowans, Eric J

    2014-04-01

    The failure of traditional protein-based vaccines to prevent infection by viruses such as HIV or hepatitis C highlights the need for novel vaccine strategies. DNA vaccines have shown promise in small animal models, and are effective at generating anti-viral T cell-mediated immune responses; however, they have proved to be poorly immunogenic in clinical trials. We propose that the induction of necrosis will enhance the immune response to vaccine antigens encoded by DNA vaccines, as necrotic cells are known to release a range of intracellular factors that lead to dendritic cell (DC) activation and enhanced cross-presentation of antigen. Here we provide evidence that induction of cell death in DNA vaccine-targeted cells provides an adjuvant effect following intradermal vaccination of mice; however, this enhancement of the immune response is dependent on both the mechanism and timing of cell death after antigen expression. We report that a DNA vaccine encoding the cytolytic protein, perforin, resulted in DC activation, enhanced broad and multifunctional CD8 T-cell responses to the HIV-1 antigen GAG and reduced viral load following challenge with a chimeric virus, EcoHIV, compared with the canonical GAG DNA vaccine. This effect was not observed for a DNA vaccine encoding an apoptosis-inducing toxin, DTa, or when the level of perforin expression was increased to induce cell death sooner after vaccination. Thus, inducing lytic cell death following a threshold level of expression of a viral antigen can improve the immunogenicity of DNA vaccines, whereas apoptotic cell death has an inhibitory effect on the immune response.

  1. An adaptive line enhancement method for UWB proximity fuze signal processing based on correlation matrix estimation with time delay factor

    NASA Astrophysics Data System (ADS)

    Li, Meng; Huang, Zhonghua

    2016-10-01

    Signal processing for an ultra-wideband radio fuze receiver involves some challenges: it requires high real-time performance; the output signal is mixed with broadband noise; and the signal-to-noise ratio (SNR) decreases with increased detection range. The adaptive line enhancement method is used to filter the output signal of the ultra-wideband radio fuze receiver, and thus suppress the wideband noise from the output signal of the receiver and extract the target characteristic signal. The filter input correlation matrix estimation algorithm is based on the delay factor of an adaptive line enhancer. The proposed adaptive algorithm was used to filter and reduce noise in the output signal from the fuze receiver. Simulation results showed that the SNR of the output signal after adaptive noise reduction was improved by 20 dB, which was higher than the SNR of the output signal after finite impulse response (FIR) filtering of around 10 dB.

  2. Mg-Protoporphyrin IX Signals Enhance Plant's Tolerance to Cold Stress.

    PubMed

    Zhang, Zhong-Wei; Wu, Zi-Li; Feng, Ling-Yang; Dong, Li-Hua; Song, An-Jun; Yuan, Ming; Chen, Yang-Er; Zeng, Jian; Chen, Guang-Deng; Yuan, Shu

    2016-01-01

    The relationship between Mg-protoporphyrin IX (Mg-Proto IX) signals and plant's tolerance to cold stress is investigated. Arabidopsis seedlings grown for 3 weeks were pretreated with 2 mM glutamate (Glu) and 2 mM MgCl2 for 48 h at room temperature to induce Mg-Proto IX accumulation. Then cold stress was performed at 4°C for additional 72 h. Glu + MgCl2 pre-treatments alleviated the subsequent cold stress significantly by rising the leaf temperature through inducing Mg-Proto IX signals. The protective role of Glu + MgCl2 treatment was greatly compromised in the mutants of Mg-Proto IX synthesis, Mg-Proto IX signaling, and cyanide-resistant respiration. And the enhancement of cold-responsive gene expression was greatly compromised in the mutants of Mg-Proto IX synthesis, Mg-Proto IX signaling and ABA signaling, but not in the mutant of cyanide-resistant respiration. Cold stress promoted cyanide-resistant respiration and leaf total respiration exponentially, which could be further induced by the Glu + MgCl2 treatment. Mg-Proto IX signals also activate antioxidant enzymes and increase non-enzymatic antioxidants [glutathione but not ascorbic acid (AsA)] to maintain redox equilibrium during the cold stress.

  3. Signal enhancement in polarized light imaging by means of independent component analysis.

    PubMed

    Dammers, Jürgen; Axer, Markus; Grässel, David; Palm, Christoph; Zilles, Karl; Amunts, Katrin; Pietrzyk, Uwe

    2010-01-15

    Polarized light imaging (PLI) enables the evaluation of fiber orientations in histological sections of human postmortem brains, with ultra-high spatial resolution. PLI is based on the birefringent properties of the myelin sheath of nerve fibers. As a result, the polarization state of light propagating through a rotating polarimeter is changed in such a way that the detected signal at each measurement unit of a charged-coupled device (CCD) camera describes a sinusoidal signal. Vectors of the fiber orientation defined by inclination and direction angles can then directly be derived from the optical signals employing PLI analysis. However, noise, light scatter and filter inhomogeneities interfere with the original sinusoidal PLI signals. We here introduce a novel method using independent component analysis (ICA) to decompose the PLI images into statistically independent component maps. After decomposition, gray and white matter structures can clearly be distinguished from noise and other artifacts. The signal enhancement after artifact rejection is quantitatively evaluated in 134 histological whole brain sections. Thus, the primary sinusoidal signals from polarized light imaging can be effectively restored after noise and artifact rejection utilizing ICA. Our method therefore contributes to the analysis of nerve fiber orientation in the human brain within a micrometer scale.

  4. Mg-Protoporphyrin IX Signals Enhance Plant’s Tolerance to Cold Stress

    PubMed Central

    Zhang, Zhong-Wei; Wu, Zi-Li; Feng, Ling-Yang; Dong, Li-Hua; Song, An-Jun; Yuan, Ming; Chen, Yang-Er; Zeng, Jian; Chen, Guang-Deng; Yuan, Shu

    2016-01-01

    The relationship between Mg-protoporphyrin IX (Mg-Proto IX) signals and plant’s tolerance to cold stress is investigated. Arabidopsis seedlings grown for 3 weeks were pretreated with 2 mM glutamate (Glu) and 2 mM MgCl2 for 48 h at room temperature to induce Mg-Proto IX accumulation. Then cold stress was performed at 4°C for additional 72 h. Glu + MgCl2 pre-treatments alleviated the subsequent cold stress significantly by rising the leaf temperature through inducing Mg-Proto IX signals. The protective role of Glu + MgCl2 treatment was greatly compromised in the mutants of Mg-Proto IX synthesis, Mg-Proto IX signaling, and cyanide-resistant respiration. And the enhancement of cold-responsive gene expression was greatly compromised in the mutants of Mg-Proto IX synthesis, Mg-Proto IX signaling and ABA signaling, but not in the mutant of cyanide-resistant respiration. Cold stress promoted cyanide-resistant respiration and leaf total respiration exponentially, which could be further induced by the Glu + MgCl2 treatment. Mg-Proto IX signals also activate antioxidant enzymes and increase non-enzymatic antioxidants [glutathione but not ascorbic acid (AsA)] to maintain redox equilibrium during the cold stress. PMID:27803706

  5. Canonical Wnt signaling transiently stimulates proliferation and enhances neurogenesis in neonatal neural progenitor cultures

    SciTech Connect

    Hirsch, Cordula; Campano, Louise M.; Woehrle, Simon; Hecht, Andreas . E-mail: andreas.hecht@mol-med.uni-freiburg.de

    2007-02-01

    Canonical Wnt signaling triggers the formation of heterodimeric transcription factor complexes consisting of {beta}-catenin and T cell factors, and thereby controls the execution of specific genetic programs. During the expansion and neurogenic phases of embryonic neural development canonical Wnt signaling initially controls proliferation of neural progenitor cells, and later neuronal differentiation. Whether Wnt growth factors affect neural progenitor cells postnatally is not known. Therefore, we have analyzed the impact of Wnt signaling on neural progenitors isolated from cerebral cortices of newborn mice. Expression profiling of pathway components revealed that these cells are fully equipped to respond to Wnt signals. However, Wnt pathway activation affected only a subset of neonatal progenitors and elicited a limited increase in proliferation and neuronal differentiation in distinct subsets of cells. Moreover, Wnt pathway activation only transiently stimulated S-phase entry but did not support long-term proliferation of progenitor cultures. The dampened nature of the Wnt response correlates with the predominant expression of inhibitory pathway components and the rapid actuation of negative feedback mechanisms. Interestingly, in differentiating cell cultures activation of canonical Wnt signaling reduced Hes1 and Hes5 expression suggesting that during postnatal neural development, Wnt/{beta}-catenin signaling enhances neurogenesis from progenitor cells by interfering with Notch pathway activity.

  6. RAS–Mitogen-Activated Protein Kinase Signal Is Required for Enhanced PD-L1 Expression in Human Lung Cancers

    PubMed Central

    Sumimoto, Hidetoshi; Takano, Atsushi; Teramoto, Koji; Daigo, Yataro

    2016-01-01

    Ectopic programmed cell death ligand 1 (PD-L1) expression in non-small cell lung cancers (NSCLCs) is related to immune evasion by cancer, and it is a molecular target of immune checkpoint therapies. Although some altered signals in NSCLCs are responsible for ectopic PD-L1 expression, the precise mechanisms remain obscure. Because we found a higher frequency of EGFR/KRAS mutations in NSCLC cell lines with high PD-L1 expression (p < 0.001), we evaluated the relationships between downstream signals and PD-L1 expression, particularly in three KRAS-mutant adenocarcinoma cell lines. The MEK inhibitor U0126 (20 μM) significantly decreased the surface PD-L1 levels by 50–60% compared with dimethyl sulfoxide (p < 0.0001). Phorbol 12-myristate 13-acetate stimulation (100 nM, 15 min) increased (p < 0.05) and two ERK2 siRNAs as well as KRAS siRNAs decreased (p < 0.05) PD-L1 expression. The transcriptional activity of the potential AP-1 site (+4785 to +5056 from the transcription start site) in the PD-L1 gene was demonstrated by luciferase assays, which was inhibited by U0126. The chromatin immunoprecipitation assay demonstrated the binding of cJUN to the AP-1 site. Two STAT3 siRNAs decreased PD-L1 expression by 10–32% in two of the three KRAS-mutant lung adenocarcinoma cell lines (p < 0.05), while the PI3K inhibitor LY294002 (40 μM) did not change the expression level. Supervised cluster analysis and gene set enrichment analysis between the PD-L1-high and -low NSCLCs revealed a correlation between PD-L1 expression and genes/pathways related to cell motility/adhesion. These results indicate that MAPK signaling is the dominant downstream signal responsible for ectopic PD-L1 expression, in which STAT3 is also involved to some extent. Furthermore, MAPK signaling may control the expression of PD-L1 and several genes related to enhanced cell motility. Our findings suggest that MAPK, along with STAT3, is important for determining PD-L1 expression, which could be useful for

  7. Insulin enhances striatal dopamine release by activating cholinergic interneurons and thereby signals reward

    PubMed Central

    Stouffer, Melissa A.; Woods, Catherine A.; Patel, Jyoti C.; Lee, Christian R.; Witkovsky, Paul; Bao, Li; Machold, Robert P.; Jones, Kymry T.; de Vaca, Soledad Cabeza; Reith, Maarten E. A.; Carr, Kenneth D.; Rice, Margaret E.

    2015-01-01

    Insulin activates insulin receptors (InsRs) in the hypothalamus to signal satiety after a meal. However, the rising incidence of obesity, which results in chronically elevated insulin levels, implies that insulin may also act in brain centres that regulate motivation and reward. We report here that insulin can amplify action potential-dependent dopamine (DA) release in the nucleus accumbens (NAc) and caudate–putamen through an indirect mechanism that involves striatal cholinergic interneurons that express InsRs. Furthermore, two different chronic diet manipulations in rats, food restriction (FR) and an obesogenic (OB) diet, oppositely alter the sensitivity of striatal DA release to insulin, with enhanced responsiveness in FR, but loss of responsiveness in OB. Behavioural studies show that intact insulin levels in the NAc shell are necessary for acquisition of preference for the flavour of a paired glucose solution. Together, these data imply that striatal insulin signalling enhances DA release to influence food choices. PMID:26503322

  8. Insulin enhances striatal dopamine release by activating cholinergic interneurons and thereby signals reward.

    PubMed

    Stouffer, Melissa A; Woods, Catherine A; Patel, Jyoti C; Lee, Christian R; Witkovsky, Paul; Bao, Li; Machold, Robert P; Jones, Kymry T; de Vaca, Soledad Cabeza; Reith, Maarten E A; Carr, Kenneth D; Rice, Margaret E

    2015-10-27

    Insulin activates insulin receptors (InsRs) in the hypothalamus to signal satiety after a meal. However, the rising incidence of obesity, which results in chronically elevated insulin levels, implies that insulin may also act in brain centres that regulate motivation and reward. We report here that insulin can amplify action potential-dependent dopamine (DA) release in the nucleus accumbens (NAc) and caudate-putamen through an indirect mechanism that involves striatal cholinergic interneurons that express InsRs. Furthermore, two different chronic diet manipulations in rats, food restriction (FR) and an obesogenic (OB) diet, oppositely alter the sensitivity of striatal DA release to insulin, with enhanced responsiveness in FR, but loss of responsiveness in OB. Behavioural studies show that intact insulin levels in the NAc shell are necessary for acquisition of preference for the flavour of a paired glucose solution. Together, these data imply that striatal insulin signalling enhances DA release to influence food choices.

  9. A Lys49-PLA2 myotoxin of Bothrops asper triggers a rapid death of macrophages that involves autocrine purinergic receptor signaling

    PubMed Central

    Tonello, F; Simonato, M; Aita, A; Pizzo, P; Fernández, J; Lomonte, B; Gutiérrez, J M; Montecucco, C

    2012-01-01

    Lys49-PLA2 myotoxins, an important component of various viperid snake venoms, are a class of PLA2-homolog proteins deprived of catalytic activity. Similar to enzymatically active PLA2 (Asp49) and to other classes of myotoxins, they cause severe myonecrosis. Moreover, these toxins are used as tools to study skeletal muscle repair and regeneration, a process that can be very limited after snakebites. In this work, the cytotoxic effect of different myotoxins, Bothrops asper Lys49 and Asp49-PLA2, Notechis scutatus notexin and Naja mossambica cardiotoxin, was evaluated on macrophages, cells that have a key role in muscle regeneration. Only the Lys49-myotoxin was found to trigger a rapid asynchronous death of mouse peritoneal macrophages and macrophagic cell lines through a process that involves ATP release, ATP-induced ATP release and that is inhibited by various purinergic receptor antagonists. ATP leakage is induced also at sublytical doses of the Lys49-myotoxin, it involves Ca2+ release from intracellular stores, and is reduced by inhibitors of VSOR and the maxi-anion channel. The toxin-induced cell death is different from that caused by high concentration of ATP and appears to be linked to localized purinergic signaling. Based on present findings, a mechanism of cell death is proposed that can be extended to other cytolytic proteins and peptides. PMID:22764102

  10. RepA Protein Encoded by Oat dwarf virus Elicits a Temperature-Sensitive Hypersensitive Response-Type Cell Death That Involves Jasmonic Acid-Dependent Signaling.

    PubMed

    Qian, Yajuan; Hou, Huwei; Shen, Qingtang; Cai, Xinzhong; Sunter, Garry; Zhou, Xueping

    2016-01-01

    The hypersensitive response (HR) is a component of disease resistance that is often induced by pathogen infection, but essentially no information is available for members of the destructive mastreviruses. We have investigated an HR-type response elicited in Nicotiana species by Oat dwarf virus (ODV) and have found that expression of the ODV RepA protein but not other ODV-encoded proteins elicits the HR-type cell death associated with a burst of H2O2. Deletion mutagenesis indicates that the first nine amino acids (aa) at the N terminus of RepA and the two regions located between aa residues 173 and 195 and between aa residues 241 and 260 near the C terminus are essential for HR-type cell-death elicitation. Confocal and electron microscopy showed that the RepA protein is localized in the nuclei of plant cells and might contain bipartite nuclear localization signals. The HR-like lesions mediated by RepA were inhibited by temperatures above 30°C and involvement of jasmonic acid (JA) in HR was identified by gain- and loss-of-function experiments. To our knowledge, this is the first report of an elicitor of HR-type cell death from mastreviruses.

  11. Combination treatment with arsenic trioxide and phytosphingosine enhances apoptotic cell death in arsenic trioxide-resistant cancer cells.

    PubMed

    Park, Moon-Taek; Kang, Young-Hee; Park, In-Chul; Kim, Chun-Ho; Lee, Yun-Sil; Chung, Hee Yong; Lee, Su-Jae

    2007-01-01

    Resistance to anticancer drugs can sometimes be overcome by combination treatment with other therapeutic drugs. Here, we showed that phytosphingosine treatment in combination with arsenic trioxide (As(2)O(3)) enhanced cell death of naturally As(2)O(3)-resistant human myeloid leukemia cells. The combination treatment induced an increase in intracellular reactive oxygen species level, mitochondrial relocalization of Bax, poly(ADP-ribose) polymerase-1 (PARP-1) activation, and cytochrome c release from the mitochondria. N-acetyl-l-cysteine, a thiol-containing antioxidant, completely blocked Bax relocalization, PARP-1 activation, and cytochrome c release. Pretreatment of 3,4-dihydro-5-[4-(1-piperidinyl)butoxy]-1(2H)-isoquinolinone, a PARP-1 inhibitor, or PARP-1/small interfering RNA partially attenuated cytochrome c release, whereas the same treatment did not affect Bax relocalization. The combination treatment induced selective activation of p38 mitogen-activated protein kinase (MAPK). Inhibition of p38 MAPK by treatment of SB203580 or expression of dominant-negative forms of p38 MAPK suppressed the combination treatment-induced Bax relocalization but did not affect PARP-1 activation. In addition, antioxidant N-acetyl-l-cysteine completely blocked p38 MAPK activation. These results indicate that phytosphingosine in combination with As(2)O(3) induces synergistic apoptosis in As(2)O(3)-resistant leukemia cells through the p38 MAPK-mediated mitochondrial translocation of Bax and the PARP-1 activation, and that p38 MAPK and PARP-1 activations are reactive oxygen species dependent. The molecular mechanism that we elucidated in this study may provide insight into the design of future combination cancer therapies to cells intrinsically less sensitive to As(2)O(3) treatment.

  12. Metformin enhances glucagon-like peptide 1 via cooperation between insulin and Wnt signaling.

    PubMed

    Kim, Mi-Hyun; Jee, Jae-Hwan; Park, Sunyoung; Lee, Myung-Shik; Kim, Kwang-Won; Lee, Moon-Kyu

    2014-02-01

    One aspect of the effects of metformin on glucagon-like peptide (GLP)-1 might be associated with the mechanism by which the cross talk between insulin and Wnt signaling enhances GLP1 secretion, due to the action of metformin as an insulin sensitizer. However, this remains completely unknown. In this study, we have investigated the mechanisms of the action of metformin on cross talk between insulin and Wnt signaling. GLP1 enhancement by meformin was determined in human NCI-H716 intestinal L-cells and hyperglycemic db/db mice treated with metformin (0.25 and 0.5 mM and/or 12.5 mg/kg body weight) for 24 h and 2 months. Metformin increased GLP1 secretion in L-cells and db/db mice. Metformin stimulated the nuclear translocation of β-catenin and TOPflash reporter activity, and gene depletion of β-catenin or enhancement of mutation of transcription factor 7-like 2 binding site offset GLP1. In addition, insulin receptor substrate 2 gene depletion blocked metformin-enhanced β-catenin translocation. These effects were preceded by an increase in glucose utilization and calcium influx, the activation of calcium-dependent protein kinase, and, in turn, the activation of insulin signaling, and the inhibition of glycogen synthase kinase 3β, a potent inhibitor of β-catenin. Furthermore, high blood glucose levels were controlled via GLP1 receptor-dependent insulinotropic pathways in db/db mice, which were evidenced by the increase in GLP1 and insulin levels at 30 min after oral glucose loading and pancreatic insulinotropic gene expression. Our findings indicate that the cooperation between Wnt and its upstream insulin signaling pathways might be a novel and important mechanism underlying the effects of metformin on GLP1 production.

  13. Bio-nanocapsules for signal enhancement of alkaline phosphatase-linked immunosorbent assays.

    PubMed

    Iijima, Masumi; Yamamoto, Mikako; Yoshimoto, Nobuo; Niimi, Tomoaki; Kuroda, Shun'ichi

    2013-01-01

    The bio-nanocapsules displaying about 240 molecules of immunoglobulin G Fc-binding Z domains (ZZ-BNCs) enhanced the signals of enzyme-linked immunosorbent assay by tethering the Fc regions of secondary antibodies (Abs), which were eliminated using high-molecular mass enzymes (e.g., alkaline phosphatase). By way of optimizing the distance between enzymes and Abs, ZZ-BNCs improved sensitivity independently of enzymes.

  14. Fusarium Oxysporum Volatiles Enhance Plant Growth Via Affecting Auxin Transport and Signaling.

    PubMed

    Bitas, Vasileios; McCartney, Nathaniel; Li, Ningxiao; Demers, Jill; Kim, Jung-Eun; Kim, Hye-Seon; Brown, Kathleen M; Kang, Seogchan

    2015-01-01

    Volatile organic compounds (VOCs) have well-documented roles in plant-plant communication and directing animal behavior. In this study, we examine the less understood roles of VOCs in plant-fungal relationships. Phylogenetically and ecologically diverse strains of Fusarium oxysporum, a fungal species complex that often resides in the rhizosphere of assorted plants, produce volatile compounds that augment shoot and root growth of Arabidopsis thaliana and tobacco. Growth responses of A. thaliana hormone signaling mutants and expression patterns of a GUS reporter gene under the auxin-responsive DR5 promoter supported the involvement of auxin signaling in F. oxysporum volatile-mediated growth enhancement. In addition, 1-naphthylthalamic acid, an inhibitor of auxin efflux, negated F. oxysporum volatile-mediated growth enhancement in both plants. Comparison of the profiles of volatile compounds produced by F. oxysporum strains that differentially affected plant growth suggests that the relative compositions of both growth inhibitory and stimulatory compounds may determine the degree of plant growth enhancement. Volatile-mediated signaling between fungi and plants may represent a potentially conserved, yet mostly overlooked, mechanism underpinning plant-fungus interactions and fungal niche adaption.

  15. Phosphatidylserine enhances IKBKAP transcription by activating the MAPK/ERK signaling pathway.

    PubMed

    Donyo, Maya; Hollander, Dror; Abramovitch, Ziv; Naftelberg, Shiran; Ast, Gil

    2016-04-01

    Familial dysautonomia (FD) is a genetic disorder manifested due to abnormal development and progressive degeneration of the sensory and autonomic nervous system. FD is caused by a point mutation in the IKBKAP gene encoding the IKAP protein, resulting in decreased protein levels. A promising potential treatment for FD is phosphatidylserine (PS); however, the manner by which PS elevates IKAP levels has yet to be identified. Analysis of ChIP-seq results of the IKBKAP promoter region revealed binding of the transcription factors CREB and ELK1, which are regulated by the mitogen-activated protein kinase (MAPK)/extracellular-regulated kinase (ERK) signaling pathway. We show that PS treatment enhanced ERK phosphorylation in cells derived from FD patients. ERK activation resulted in elevated IKBKAP transcription and IKAP protein levels, whereas pretreatment with the MAPK inhibitor U0126 blocked elevation of the IKAP protein level. Overexpression of either ELK1 or CREB activated the IKBKAP promoter, whereas downregulation of these transcription factors resulted in a decrease of the IKAP protein. Additionally, we show that PS improves cell migration, known to be enhanced by MAPK/ERK activation and abrogated in FD cells. In conclusion, our results demonstrate that PS activates the MAPK/ERK signaling pathway, resulting in activation of transcription factors that bind the promoter region of IKBKAP and thus enhancing its transcription. Therefore, compounds that activate the MAPK/ERK signaling pathway could constitute potential treatments for FD.

  16. Fusarium Oxysporum Volatiles Enhance Plant Growth Via Affecting Auxin Transport and Signaling

    PubMed Central

    Bitas, Vasileios; McCartney, Nathaniel; Li, Ningxiao; Demers, Jill; Kim, Jung-Eun; Kim, Hye-Seon; Brown, Kathleen M.; Kang, Seogchan

    2015-01-01

    Volatile organic compounds (VOCs) have well-documented roles in plant-plant communication and directing animal behavior. In this study, we examine the less understood roles of VOCs in plant-fungal relationships. Phylogenetically and ecologically diverse strains of Fusarium oxysporum, a fungal species complex that often resides in the rhizosphere of assorted plants, produce volatile compounds that augment shoot and root growth of Arabidopsis thaliana and tobacco. Growth responses of A. thaliana hormone signaling mutants and expression patterns of a GUS reporter gene under the auxin-responsive DR5 promoter supported the involvement of auxin signaling in F. oxysporum volatile-mediated growth enhancement. In addition, 1-naphthylthalamic acid, an inhibitor of auxin efflux, negated F. oxysporum volatile-mediated growth enhancement in both plants. Comparison of the profiles of volatile compounds produced by F. oxysporum strains that differentially affected plant growth suggests that the relative compositions of both growth inhibitory and stimulatory compounds may determine the degree of plant growth enhancement. Volatile-mediated signaling between fungi and plants may represent a potentially conserved, yet mostly overlooked, mechanism underpinning plant-fungus interactions and fungal niche adaption. PMID:26617587

  17. Insulin receptor substrate 1 expression enhances the sensitivity of 32D cells to chemotherapy-induced cell death

    SciTech Connect

    Porter, Holly A.; Carey, Gregory B.; Keegan, Achsah D.

    2012-08-15

    The adapters IRS1 and IRS2 link growth factor receptors to downstream signaling pathways that regulate proliferation and survival. Both suppress factor-withdrawal-induced apoptosis and have been implicated in cancer progression. However, recent studies suggest IRS1 and IRS2 mediate differential functions in cancer pathogenesis. IRS1 promoted breast cancer proliferation, while IRS2 promoted metastasis. The role of IRS1 and IRS2 in controlling cell responses to chemotherapy is unknown. To determine the role of IRS1 and IRS2 in the sensitivity of cells to chemotherapy, we treated 32D cells lacking or expressing IRS proteins with various concentrations of chemotherapeutic agents. We found that expression of IRS1, in contrast to IRS2, enhanced the sensitivity of 32D cells to chemotherapy-induced apoptosis. When IRS2 was expressed with IRS1, the cells no longer showed enhanced sensitivity. Expression of IRS1 did not alter the expression of pro- and anti-apoptotic proteins; however, 32D-IRS1 cells expressed higher levels of Annexin A2. In 32D-IRS1 cells, IRS1 and Annexin A2 were both located in cytoplasmic and membrane fractions. We also found that IRS1 coprecipitated with Annexin A2, while IRS2 did not. Decreasing Annexin A2 levels reduced 32D-IRS1 cell sensitivity to chemotherapy. These results suggest IRS1 enhances sensitivity to chemotherapy in part through Annexin A2. -- Highlights: Black-Right-Pointing-Pointer IRS1 enhanced the sensitivity of 32D cells to chemotherapy-induced apoptosis. Black-Right-Pointing-Pointer This sensitivity is abrogated by the expression of IRS2. Black-Right-Pointing-Pointer Expressing IRS1 in 32D cells increased levels of Annexin A2. Black-Right-Pointing-Pointer Both IRS1 and Annexin A2 were located in cytoplasmic and membrane fractions. Black-Right-Pointing-Pointer Decreasing Annexin A2 in 32D-IRS1 cells abated their sensitivity to chemotherapy.

  18. Enhanced brain signal variability in children with autism spectrum disorder during early childhood

    PubMed Central

    Yoshimura, Yuko; Hiraishi, Hirotoshi; Hasegawa, Chiaki; Munesue, Toshio; Higashida, Haruhiro; Minabe, Yoshio; Kikuchi, Mitsuru

    2016-01-01

    Abstract Extensive evidence shows that a core neurobiological mechanism of autism spectrum disorder (ASD) involves aberrant neural connectivity. Recent advances in the investigation of brain signal variability have yielded important information about neural network mechanisms. That information has been applied fruitfully to the assessment of aging and mental disorders. Multiscale entropy (MSE) analysis can characterize the complexity inherent in brain signal dynamics over multiple temporal scales in the dynamics of neural networks. For this investigation, we sought to characterize the magnetoencephalography (MEG) signal variability during free watching of videos without sound using MSE in 43 children with ASD and 72 typically developing controls (TD), emphasizing early childhood to older childhood: a critical period of neural network maturation. Results revealed an age‐related increase of brain signal variability in a specific timescale in TD children, whereas atypical age‐related alteration was observed in the ASD group. Additionally, enhanced brain signal variability was observed in children with ASD, and was confirmed particularly for younger children. In the ASD group, symptom severity was associated region‐specifically and timescale‐specifically with reduced brain signal variability. These results agree well with a recently reported theory of increased brain signal variability during development and aberrant neural connectivity in ASD, especially during early childhood. Results of this study suggest that MSE analytic method might serve as a useful approach for characterizing neurophysiological mechanisms of typical‐developing and its alterations in ASD through the detection of MEG signal variability at multiple timescales. Hum Brain Mapp 37:1038–1050, 2016. © 2015 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. PMID:26859309

  19. Daunorubicin induces cell death via activation of apoptotic signalling pathway and inactivation of survival pathway in muscle-derived stem cells.

    PubMed

    Stulpinas, Aurimas; Imbrasaitė, Aušra; Kalvelytė, Audronė Valerija

    2012-04-01

    Daunorubicin (as well as other anthracyclines) is known to be toxic to heart cells and other cells in organism thus limiting its applicability in human cancer therapy. To investigate possible mechanisms of daunorubicin cytotoxicity, we used stem cell lines derived from adult rabbit skeletal muscle. Recently, we have shown that daunorubicin induces apoptotic cell death in our cell model system and distinctly influences the activity of MAP kinases. Here, we demonstrate that two widely accepted antagonistic signalling pathways namely proapoptotic JNK and prosurvival PI3K/AKT participate in apoptosis. Using the Western blot method, we observed the activation of JNK and phosphorylation of its direct target c-Jun along with inactivation of AKT and its direct target GSK in the course of programmed cell death. By means of small-molecule kinase inhibitors and transfection of cells with the genes of the components of these pathways, c-Jun and AKT, we confirm that JNK signalling pathway is proapoptotic, whereas AKT is antiapoptotic in daunorubicin-induced muscle cells. These findings could contribute to new approaches which will result in less toxicity and fewer side effects that are currently associated with the use of daunorubicin in cancer therapies.

  20. Timeseries Signal Processing for Enhancing Mobile Surveys: Learning from Field Studies

    NASA Astrophysics Data System (ADS)

    Risk, D. A.; Lavoie, M.; Marshall, A. D.; Baillie, J.; Atherton, E. E.; Laybolt, W. D.

    2015-12-01

    Vehicle-based surveys using laser and other analyzers are now commonplace in research and industry. In many cases when these studies target biologically-relevant gases like methane and carbon dioxide, the minimum detection limits are often coarse (ppm) relative to the analyzer's capabilities (ppb), because of the inherent variability in the ambient background concentrations across the landscape that creates noise and uncertainty. This variation arises from localized biological sinks and sources, but also atmospheric turbulence, air pooling, and other factors. Computational processing routines are widely used in many fields to increase resolution of a target signal in temporally dense data, and offer promise for enhancing mobile surveying techniques. Signal processing routines can both help identify anomalies at very low levels, or can be used inversely to remove localized industrially-emitted anomalies from ecological data. This presentation integrates learnings from various studies in which simple signal processing routines were used successfully to isolate different temporally-varying components of 1 Hz timeseries measured with laser- and UV fluorescence-based analyzers. As illustrative datasets, we present results from industrial fugitive emission studies from across Canada's western provinces and other locations, and also an ecological study that aimed to model near-surface concentration variability across different biomes within eastern Canada. In these cases, signal processing algorithms contributed significantly to the clarity of both industrial, and ecological processes. In some instances, signal processing was too computationally intensive for real-time in-vehicle processing, but we identified workarounds for analyzer-embedded software that contributed to an improvement in real-time resolution of small anomalies. Signal processing is a natural accompaniment to these datasets, and many avenues are open to researchers who wish to enhance existing, and future

  1. Programmable ion-sensitive transistor interfaces. III. Design considerations, signal generation, and sensitivity enhancement

    NASA Astrophysics Data System (ADS)

    Jayant, Krishna; Auluck, Kshitij; Rodriguez, Sergio; Cao, Yingqiu; Kan, Edwin C.

    2014-05-01

    We report on factors that affect DNA hybridization detection using ion-sensitive field-effect transistors (ISFETs). Signal generation at the interface between the transistor and immobilized biomolecules is widely ascribed to unscreened molecular charges causing a shift in surface potential and hence the transistor output current. Traditionally, the interaction between DNA and the dielectric or metal sensing interface is modeled by treating the molecular layer as a sheet charge and the ionic profile with a Poisson-Boltzmann distribution. The surface potential under this scenario is described by the Graham equation. This approximation, however, often fails to explain large hybridization signals on the order of tens of mV. More realistic descriptions of the DNA-transistor interface which include factors such as ion permeation, exclusion, and packing constraints have been proposed with little or no corroboration against experimental findings. In this study, we examine such physical models by their assumptions, range of validity, and limitations. We compare simulations against experiments performed on electrolyte-oxide-semiconductor capacitors and foundry-ready floating-gate ISFETs. We find that with weakly charged interfaces (i.e., low intrinsic interface charge), pertinent to the surfaces used in this study, the best agreement between theory and experiment exists when ions are completely excluded from the DNA layer. The influence of various factors such as bulk pH, background salinity, chemical reactivity of surface groups, target molecule concentration, and surface coatings on signal generation is studied. Furthermore, in order to overcome Debye screening limited detection, we suggest two signal enhancement strategies. We first describe frequency domain biosensing, highlighting the ability to sort short DNA strands based on molecular length, and then describe DNA biosensing in multielectrolytes comprising trace amounts of higher-valency salt in a background of

  2. Chalcone flavokawain B induces autophagic-cell death via reactive oxygen species-mediated signaling pathways in human gastric carcinoma and suppresses tumor growth in nude mice.

    PubMed

    Chang, Chia-Ting; Hseu, You-Cheng; Thiyagarajan, Varadharajan; Lin, Kai-Yuan; Way, Tzong-Der; Korivi, Mallikarjuna; Liao, Jiuun-Wang; Yang, Hsin-Ling

    2017-04-03

    Flavokawain B (FKB), a naturally occurring chalcone in kava extracts, has been reported to possess anticancer activity. However, the effect of FKB on gastric cancer remains unclear. We examined the in vitro and in vivo anticancer activity and autophagy involvement of FKB and determined the underlying molecular mechanisms. FKB is potently cytotoxic to human gastric cancer cells (AGS/NCI-N87/KATO-III/TSGH9201) and mildly toxic towards normal (Hs738) cells and primary mouse hepatocytes. FKB-induced AGS cell death was characterized by autophagy, not apoptosis, as evidenced by increased LC3-II accumulation, GFP-LC3 puncta and acidic vesicular organelles (AVOs) formation, without resulting procaspase-3/PARP cleavage. FKB further caused p62/SQSTM1 activation, mTOR downregulation, ATG4B inhibition, and Beclin-1/Bcl-2 dysregulation. Silencing autophagy inhibitors CQ/3-MA and LC3 (shRNA) significantly reversed the FKB-induced cell death of AGS cells. FKB-triggered ROS generation and ROS inhibition by NAC pre-treatment diminished FKB-induced cell death, LC3 conversion, AVO formation, p62/SQSTM1 activation, ATG4B inhibition and Beclin-1/Bcl-2 dysregulation, which indicated ROS-mediated autophagy in AGS cells. Furthermore, FKB induces G2/M arrest and alters cell-cycle proteins through ROS-JNK signaling. Interestingly, FKB-induced autophagy is associated with the suppression of HER-2 and PI3K/AKT/mTOR signaling cascades. FKB inhibits apoptotic Bax expression, and Bax-transfected AGS cells exhibit both apoptosis and autophagy; thus, FKB-inactivated Bax results in apoptosis inhibition. In vivo data demonstrated that FKB effectively inhibited tumor growth, prolonged the survival rate, and induced autophagy in AGS-xenografted mice. Notably, silencing of LC3 attenuated FKB-induced autophagy in AGS-xenografted tumors. FKB may be a potential chemopreventive agent in the activation of ROS-mediated autophagy of gastric cancer cells.

  3. N-acetylcysteine attenuates hexavalent chromium-induced hypersensitivity through inhibition of cell death, ROS-related signaling and cytokine expression.

    PubMed

    Lee, Yu-Hsuan; Su, Shih-Bin; Huang, Chien-Cheng; Sheu, Hamm-Ming; Tsai, Jui-Chen; Lin, Chia-Ho; Wang, Ying-Jan; Wang, Bour-Jr

    2014-01-01

    Chromium hypersensitivity (chromium-induced allergic contact dermatitis) is an important issue in occupational skin disease. Hexavalent chromium (Cr (VI)) can activate the Akt, Nuclear factor κB (NF-κB), and Mitogen-activated protein kinase (MAPK) pathways and induce cell death, via the effects of reactive oxygen species (ROS). Recently, cell death stimuli have been proposed to regulate the release of inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1). However, the exact effects of ROS on the signaling molecules and cytotoxicity involved in Cr(VI)-induced hypersensitivity have not yet been fully demonstrated. N-acetylcysteine (NAC) could increase glutathione levels in the skin and act as an antioxidant. In this study, we investigated the effects of NAC on attenuating the Cr(VI)-triggered ROS signaling in both normal keratinocyte cells (HaCaT cells) and a guinea pig (GP) model. The results showed the induction of apoptosis, autophagy and ROS were observed after different concentrations of Cr(VI) treatment. HaCaT cells pretreated with NAC exhibited a decrease in apoptosis and autophagy, which could affect cell viability. In addition, Cr (VI) activated the Akt, NF-κB and MAPK pathways thereby increasing IL-1α and TNF-α production. However, all of these stimulation phenomena could be inhibited by NAC in both of in vitro and in vivo studies. These novel findings indicate that NAC may prevent the development of chromium hypersensitivity by inhibiting of ROS-induced cell death and cytokine expression.

  4. The phosphorylation of Hsp20 enhances its association with amyloid-β to increase protection against neuronal cell death.

    PubMed

    Cameron, Ryan T; Quinn, Steven D; Cairns, Lynn S; MacLeod, Ruth; Samuel, Ifor D W; Smith, Brian O; Carlos Penedo, J; Baillie, George S

    2014-07-01

    Up-regulation of Hsp20 protein levels in response to amyloid fibril formation is considered a key protective response against the onset of Alzheimer's disease (AD). Indeed, the physical interaction between Hsp20 and Aβ is known to prevent Aβ oligomerisation and protects neuronal cells from Aβ mediated toxicity, however, details of the molecular mechanism and regulatory cell signalling events behind this process have remained elusive. Using both conventional MTT end-point assays and novel real time measurement of cell impedance, we show that Hsp20 protects human neuroblastoma SH-SY5Y cells from the neurotoxic effects of Aβ. In an attempt to provide a mechanism for the neuroprotection afforded by Hsp20, we used peptide array, co-immunoprecipitation analysis and NMR techniques to map the interaction between Hsp20 and Aβ and report a binding mode where Hsp20 binds adjacent to the oligomerisation domain of Aβ, preventing aggregation. The Hsp20/Aβ interaction is enhanced by Hsp20 phosphorylation, which serves to increase association with low molecular weight Aβ species and decrease the effective concentration of Hsp20 required to disrupt the formation of amyloid oligomers. Finally, using a novel fluorescent assay for the real time evaluation of morphology-specific Aβ aggregation, we show that phospho-dependency of this effect is more pronounced for fibrils than for globular Aβ forms and that 25mers corresponding to the Hsp20 N-terminal can be used as Aβ aggregate inhibitors. Our report is the first to provide a molecular model for the Hsp20/Aβ complex and the first to suggest that modulation of the cAMP/cGMP pathways could be a novel route to enhance Hsp20-mediated attenuation of Aβ fibril neurotoxicity.

  5. Dietary phytochemicals and cancer prevention: Nrf2 signaling, epigenetics, and cell death mechanisms in blocking cancer initiation and progression

    PubMed Central

    Lee, Jong Hun; Khor, Tin Oo; Shu, Limin; Su, Zheng-Yuan; Fuentes, Francisco; Kong, Ah-Ng Tony

    2013-01-01

    Reactive metabolites from carcinogens and oxidative stress can drive genetic mutations, genomic instability, neoplastic transformation, and ultimately carcinogenesis. Numerous dietary phytochemicals in vegetables/fruits have been shown to possess cancer chemopreventive effects in both preclinical animal models and human epidemiological studies. These phytochemicals could prevent the initiation of carcinogenesis via either direct scavenging of reactive oxygen species/reactive nitrogen species (ROS/RNS) or, more importantly, the induction of cellular defense detoxifying/antioxidant enzymes. These defense enzymes mediated by Nrf2-antioxidative stress and anti-inflammatory signaling pathways can contribute to cellular protection against ROS/RNS and reactive metabolites of carcinogens. In addition, these compounds would kill initiated/transformed cancer cells in vitro and in in vivo xenografts via diverse anti-cancer mechanisms. These mechanisms include the activation of signaling kinases (e.g., JNK), caspases and the mitochondria damage/cytochrome c pathways. Phytochemicals may also have anti-cancer effects by inhibiting the IKK/NF-κB pathway, inhibiting STAT3, and causing cell cycle arrest. In addition, other mechanisms may include epigenetic alterations (e.g., inhibition of HDACs, miRNAs, and the modification of the CpG methylation of cancer-related genes). In this review, we will discuss: the current advances in the study of Nrf2 signaling; Nrf2-deficient tumor mouse models; the epigenetic control of Nrf2 in tumorigenesis and chemoprevention; Nrf2-mediated cancer chemoprevention by naturally occurring dietary phytochemicals; and the mutation or hyper-expression of the Nrf2–Keap1 signaling pathway in advanced tumor cells. The future development of dietary phytochemicals for chemoprevention must integrate in vitro signaling mechanisms, relevant biomarkers of human diseases, and combinations of different phytochemicals and/or non-toxic therapeutic drugs, including

  6. Naja nigricollis CMS-9 enhances the mitochondria-mediated death pathway in adaphostin-treated human leukaemia U937 cells.

    PubMed

    Chen, Ying-Jung; Wang, Jeh-Jeng; Chang, Long-Sen

    2011-11-01

    1. The aim of the present study was to explore the effect of the Naja nigricollis phospholipase A(2) CMS-9 on adaphostin-induced death of human leukaemia U937 cells. 2. Leukaemia U937 cells (Bcr/Abl-negative cells) were treated with adaphostin (0-10 μmol/L) and CMS-9 (0-1 μmol/L). The effects of CMS-9, adaphostin and their combination on cell viability, the generation reactive oxygen species (ROS), [Ca(2+) ](i) , p38 mitogen-activated protein kinase (MAPK) activation, Akt and extracellular signal-regulated kinase (ERK) inactivation, mitochondrial membrane potential (ΔΨ(m) ) and Bcl-2 family proteins were analysed. 3. Both adaphostin and CMS-9 induced U937 cell apoptosis, characterized by dissipation of ΔΨ(m) and ROS generation. Combined treatment further increased ΔΨ(m) loss and reduced the viability of adaphostin-treated cells. Unlike in CMS-9-treated cells, in adaphostin-treated cells ROS-induced increases in [Ca(2+) ](i) were observed. CMS-9-induced ROS generation resulted in p38 MAPK activation, whereas adaphostin treatment elicited ROS/Ca(2+) -mediated inactivation of Akt and ERK. Moreover, Akt was found to be involved in ERK phosphorylation. Suppression of p38 MAPK activation blocked CMS-9-induced ΔΨ(m) loss and Bcl-xL downregulation. Overexpression of constitutively active Akt and mitogen-activated protein kinase kinase (MEK) 1 rescued adaphostin-induced ΔΨ(m) loss and Bcl-2 downregulation. Similarly, CMS-9 augmented adaphostin toxicity in human leukaemia K562 cells via increased mitochondrial alterations. 4. The results suggest that two distinct pathways mediate adaphostin- and CMS-9-induced mitochondrial damage (i.e. the ROS-Ca(2+) -Akt-ERK and ROS-p38 MAPK pathways, respectively). These distinct pathway explain the augmentation by CMS-9 of ΔΨ(m) loss and apoptosis in adaphostin-treated U937 cells.

  7. MAPK/ERK signaling pathway-induced hyper-O-GlcNAcylation enhances cancer malignancy.

    PubMed

    Zhang, Xinling; Ma, Leina; Qi, Jieqiong; Shan, Hui; Yu, Wengong; Gu, Yuchao

    2015-12-01

    Dysregulated MAPK/ERK signaling is implicated in one-third of human tumors and represents an attractive target for the development of anticancer drugs. Similarly, elevated protein O-GlcNAcylation and O-GlcNAc transferase (OGT) are detected in various cancers and serve as attractive novel cancer-specific therapeutic targets. However, the potential connection between them remains unexplored. Here, a positive correlation was found between the activated MAPK/ERK signaling and hyper-O-GlcNAcylation in various cancer types and inhibition of the MAPK/ERK signaling by 10 µM U0126 significantly decreased the expression of OGT and O-GlcNAcylation in H1299, BPH-1 and DU145 cells; then, the pathway analysis of the potential regulators of OGT obtained from the UCSC Genome Browser was done, and ten downstream targets of ERK pathway were uncovered; the following results showed that ELK1, one of the ten targets of ERK pathway, mediated ERK signaling-induced OGT upregulation; finally, the MTT assay and the soft agar assay showed that the inhibition of MAPK/ERK signaling reduced the promotion effect of hyper-O-GlcNAcylation on cancer cell proliferation and anchorage-independent growth. Taken together, our data originally provided evidence for the regulatory mechanism of hyper-O-GlcNAcylation in tumors, which will be helpful for the development of anticancer drugs targeting to hyper-O-GlcNAcylation. This study also provided a new mechanism by which MAPK/ERK signaling-enhanced cancer malignancy. Altogether, the recently discovered oncogenic factor O-GlcNAc was linked to the classical MAPK/ERK signaling which is essential for the maintenance of malignant phenotype of cancers.

  8. Eurycomanone and eurycomanol from Eurycoma longifolia Jack as regulators of signaling pathways involved in proliferation, cell death and inflammation.

    PubMed

    Hajjouli, Shéhérazade; Chateauvieux, Sébastien; Teiten, Marie-Hélène; Orlikova, Barbora; Schumacher, Marc; Dicato, Mario; Choo, Chee-Yan; Diederich, Marc

    2014-09-16

    Eurycomanone and eurycomanol are two quassinoids from the roots of Eurycoma longifolia Jack. The aim of this study was to assess the bioactivity of these compounds in Jurkat and K562 human leukemia cell models compared to peripheral blood mononuclear cells from healthy donors. Both eurycomanone and eurycomanol inhibited Jurkat and K562 cell viability and proliferation without affecting healthy cells. Interestingly, eurycomanone inhibited NF-κB signaling through inhibition of IκBα phosphorylation and upstream mitogen activated protein kinase (MAPK) signaling, but not eurycomanol. In conclusion, both quassinoids present differential toxicity towards leukemia cells, and the presence of the α,β-unsaturated ketone in eurycomanone could be prerequisite for the NF-κB inhibition.

  9. Physcomitrella patens activates reinforcement of the cell wall, programmed cell death and accumulation of evolutionary conserved defence signals, such as salicylic acid and 12-oxo-phytodienoic acid, but not jasmonic acid, upon Botrytis cinerea infection.

    PubMed

    Ponce De León, Inés; Schmelz, Eric A; Gaggero, Carina; Castro, Alexandra; Álvarez, Alfonso; Montesano, Marcos

    2012-10-01

    The moss Physcomitrella patens is an evolutionarily basal model system suitable for the analysis of plant defence responses activated after pathogen assault. Upon infection with the necrotroph Botrytis cinerea, several defence mechanisms are induced in P. patens, including the fortification of the plant cell wall by the incorporation of phenolic compounds and the induced expression of related genes. Botrytis cinerea infection also activates the accumulation of reactive oxygen species and cell death with hallmarks of programmed cell death in moss tissues. Salicylic acid (SA) levels also increase after fungal infection, and treatment with SA enhances transcript accumulation of the defence gene phenylalanine ammonia-lyase (PAL) in P. patens colonies. The expression levels of the genes involved in 12-oxo-phytodienoic acid (OPDA) synthesis, including lipoxygenase (LOX) and allene oxide synthase (AOS), increase in P. patens gametophytes after pathogen assault, together with a rise in free linolenic acid and OPDA concentrations. However, jasmonic acid (JA) could not be detected in healthy or infected tissues of this plant. Our results suggest that, although conserved defence signals, such as SA and OPDA, are synthesized and are probably involved in the defence response of P. patens against B. cinerea infection, JA production appears to be missing. Interestingly, P. patens responds to OPDA and methyl jasmonate by reducing moss colony growth and rhizoid length, suggesting that jasmonate perception is present in mosses. Thus, P. patens can provide clues with regard to the evolution of different defence pathways in plants, including signalling and perception of OPDA and jasmonates in nonflowering and flowering plants.

  10. Artesunate induces cell death in human cancer cells via enhancing lysosomal function and lysosomal degradation of ferritin.

    PubMed

    Yang, Nai-Di; Tan, Shi-Hao; Ng, Shukie; Shi, Yin; Zhou, Jing; Tan, Kevin Shyong Wei; Wong, Wai-Shiu Fred; Shen, Han-Ming

    2014-11-28

    Artesunate (ART) is an anti-malaria drug that has been shown to exhibit anti-tumor activity, and functional lysosomes are reported to be required for ART-induced cancer cell death, whereas the underlying molecular mechanisms remain largely elusive. In this study, we aimed to elucidate the molecular mechanisms underlying ART-induced cell death. We first confirmed that ART induces apoptotic cell death in cancer cells. Interestingly, we found that ART preferably accumulates in the lysosomes and is able to activate lysosomal function via promotion of lysosomal V-ATPase assembly. Furthermore, we found that lysosomes function upstream of mitochondria in reactive oxygen species production. Importantly, we provided evidence showing that lysosomal iron is required for the lysosomal activation and mitochondrial reactive oxygen species production induced by ART. Finally, we showed that ART-induced cell death is mediated by the release of iron in the lysosomes, which results from the lysosomal degradation of ferritin, an iron storage protein. Meanwhile, overexpression of ferritin heavy chain significantly protected cells from ART-induced cell death. In addition, knockdown of nuclear receptor coactivator 4, the adaptor protein for ferritin degradation, was able to block ART-mediated ferritin degradation and rescue the ART-induced cell death. In summary, our study demonstrates that ART treatment activates lysosomal function and then promotes ferritin degradation, subsequently leading to the increase of lysosomal iron that is utilized by ART for its cytotoxic effect on cancer cells. Thus, our data reveal a new mechanistic action underlying ART-induced cell death in cancer cells.

  11. Enhancement of Notch receptor maturation and signaling sensitivity by Cripto-1.

    PubMed

    Watanabe, Kazuhide; Nagaoka, Tadahiro; Lee, Joseph M; Bianco, Caterina; Gonzales, Monica; Castro, Nadia P; Rangel, Maria Cristina; Sakamoto, Kei; Sun, Youping; Callahan, Robert; Salomon, David S

    2009-11-02

    Nodal and Notch signaling pathways play essential roles in vertebrate development. Through a yeast two-hybrid screening, we identified Notch3 as a candidate binding partner of the Nodal coreceptor Cripto-1. Coimmunoprecipitation analysis confirmed the binding of Cripto-1 with all four mammalian Notch receptors. Deletion analyses revealed that the binding of Cripto-1 and Notch1 is mediated by the Cripto-1/FRL-1/Cryptic domain of Cripto-1 and the C-terminal region of epidermal growth factor-like repeats of Notch1. Binding of Cripto-1 to Notch1 occurred mainly in the endoplasmic reticulum-Golgi network. Cripto-1 expression resulted in the recruitment of Notch1 protein into lipid raft microdomains and enhancement of the furin-like protein convertase-mediated proteolytic maturation of Notch1 (S1 cleavage). Enhanced S1 cleavage resulted in the sensitization to ligand-induced activation of Notch signaling. In addition, knockdown of Cripto-1 expression in human and mouse embryonal carcinoma cells desensitized the ligand-induced Notch signaling activation. These results suggest a novel role of Cripto-1 in facilitating the posttranslational maturation of Notch receptors.

  12. Effect of dielectric spacer thickness on signal intensity of surface plasmon field-enhanced fluorescence spectroscopy.

    PubMed

    Murakami, Takashi; Arima, Yusuke; Toda, Mitsuaki; Takiguchi, Hiromi; Iwata, Hiroo

    2012-02-15

    Surface plasmon field-enhanced fluorescence spectroscopy (SPFS) combines enhanced field platform and fluorescence detection. Its advantages are the strong intensity of the electromagnetic field and the high signal/noise (S/N) ratio due to the localized evanescent field at the water/metal interface. However, the energy transfer from the fluorophore to the metal surface diminishes the fluorescence intensity, and this reduces the sensitivity. In this study, we tested whether polystyrene (PSt) could act as a dielectric layer to suppress the energy transfer from the fluorophore to the metal surface. We hypothesized that this would improve the sensitivity of SPFS-based immunoassays. We used α-fetoprotein (AFP) as a model tumor biomarker in the sandwich-type immunoassay. We determined the relationship between fluorescent signal intensity and PSt layer thickness and compared this to theoretical predictions. We found that the fluorescence signal increased by optimally controlling the thickness of the PSt layer. Our results indicated that the SPFS-based immunoassay is a promising clinical diagnostic tool for quantitatively determining the concentrations of low-level biomarkers in blood samples.

  13. Correlation dynamics and enhanced signals for the identification of serial biomolecules and DNA bases

    NASA Astrophysics Data System (ADS)

    Ahmed, Towfiq; Haraldsen, Jason T.; Rehr, John J.; Di Ventra, Massimiliano; Schuller, Ivan; Balatsky, Alexander V.

    2014-03-01

    Nanopore-based sequencing has demonstrated a significant potential for the development of fast, accurate, and cost-efficient fingerprinting techniques for next generation molecular detection and sequencing. We propose a specific multilayered graphene-based nanopore device architecture for the recognition of single biomolecules. Molecular detection and analysis can be accomplished through the detection of transverse currents as the molecule or DNA base translocates through the nanopore. To increase the overall signal-to-noise ratio and the accuracy, we implement a new ‘multi-point cross-correlation’ technique for identification of DNA bases or other molecules on the single molecular level. We demonstrate that the cross-correlations between each nanopore will greatly enhance the transverse current signal for each molecule. We implement first-principles transport calculations for DNA bases surveyed across a multilayered graphene nanopore system to illustrate the advantages of the proposed geometry. A time-series analysis of the cross-correlation functions illustrates the potential of this method for enhancing the signal-to-noise ratio. This work constitutes a significant step forward in facilitating fingerprinting of single biomolecules using solid state technology.

  14. A simple solution for antibody signal enhancement in immunofluorescence and triple immunogold assays.

    PubMed

    Rosas-Arellano, Abraham; Villalobos-González, Juan B; Palma-Tirado, Lourdes; Beltrán, Felipe A; Cárabez-Trejo, Alfonso; Missirlis, Fanis; Castro, Maite A

    2016-10-01

    Immunolocalization techniques are standard in biomedical research. Tissue fixation with aldehydes and cell membrane permeabilization with detergents can distort the specific binding of antibodies to their high affinity epitopes. In immunofluorescence protocols, it is desirable to quench the sample's autofluorescence without reduction of the antibody-dependent signal. Here we show that adding glycine to the blocking buffer and diluting the antibodies in a phosphate saline solution containing glycine, Triton X-100, Tween20 and hydrogen peroxide increase the specific antibody signal in tissue immunofluorescence and immunogold electron microscopy. This defined antibody signal enhancer (ASE) solution gives similar results to the commercially available Pierce Immunostain Enhancer (PIE). Furthermore, prolonged tissue incubation in resin and fixative and application of ASE or PIE are described in an improved protocol for triple immunogold electron microscopy that is used to show co-localization of GABA-A ρ2 and dopamine D2 receptors in GFAP-positive astrocytes in the mouse striatum. The addition of glycine, Triton X-100, Tween20 and hydrogen peroxide during antibody incubation steps is recommended in immunohistochemistry methods.

  15. Enhanced intracellular signaling pathway in osteoblasts on ultraviolet lighttreated hydrophilic titanium.

    PubMed

    Iwasa, Fuminori; Baba, Kazuyoshi; Ogawa, Takahiro

    2016-01-01

    Ultraviolet (UV) light treatment of titanium immediately prior to use, or photofunctionalization, reactivates the time-dependent degradation of bioactivity of titanium (biological aging of titanium) and increases its osseointegration capacity beyond the inherent maximal level. Although the initial osteoblast attachment is reportedly enhanced on UV-treated titanium surfaces, the detailed mechanism behind the increase in osseointegration is unknown. This study examined the potential modulation of intracellular signaling pathway in osteoblasts on UV-treated titanium surfaces. Rat bone marrow-derived osteoblasts were cultured on 4-week-old, new, and UV-treated titanium surfaces. The new and UV-treated surfaces were superhydrophilic, whereas the 4-week-old surface was hydrophobic. Although the rate of protein adsorption was similarly increased on the new and UV-treated surfaces compared with the 4-week-old surface, the number of attached cells and their spreading behavior were further enhanced on the UV-treated surface. This additional enhancement was associated with the remarkably upregulated expression of paxillin and phospho-paxillin and exclusive upregulation of Rho GTPase family genes. This study provides with the first molecular evidence of the enhanced initial behavior of osteoblasts on UV-treated titanium surfaces. The enhancement was accentuated and distinct from the new titanium surface with similar hydrophilicity, suggesting that surface properties other than the level of hydrophilicity are responsible.

  16. Selective 14-3-3γ induction quenches p-β-catenin Ser37/Bax-enhanced cell death in cerebral cortical neurons during ischemia

    PubMed Central

    Lai, X J; Ye, S Q; Zheng, L; Li, L; Liu, Q R; Yu, S B; Pang, Y; Jin, S; Li, Q; Yu, A C H; Chen, X Q

    2014-01-01

    Ischemia-induced cell death is a major cause of disability or death after stroke. Identifying the key intrinsic protective mechanisms induced by ischemia is critical for the development of effective stroke treatment. Here, we reported that 14-3-3γ was a selective ischemia-inducible survival factor in cerebral cortical neurons reducing cell death by downregulating Bax depend direct 14-3-3γ/p-β-catenin Ser37 interactions in the nucleus. 14-3-3γ, but not other 14-3-3 isoforms, was upregulated in primary cerebral cortical neurons upon oxygen–glucose deprivation (OGD) as measured by quantitative PCR, western blot and fluorescent immunostaining. The selective induction of 14-3-3γ in cortical neurons by OGD was verified by the in vivo ischemic stroke model. Knocking down 14-3-3γ alone or inhibiting 14-3-3/client interactions was sufficient to induce cell death in normal cultured neurons and exacerbate OGD-induced neuronal death. Ectopic overexpression of 14-3-3γ significantly reduced OGD-induced cell death in cultured neurons. Co-immunoprecipitation and fluorescence resonance energy transfer demonstrated that endogenous 14-3-3γ bound directly to more p-β-catenin Ser37 but not p-Bad, p-Ask-1, p-p53 and Bax. During OGD, p-β-catenin Ser37 but not p-β-catenin Ser45 was increased prominently, which correlated with Bax elevation in cortical neurons. OGD promoted the entry of 14-3-3γ into the nuclei, in correlation with the increase of nuclear p-β-catenin Ser37 in neurons. Overexpression of 14-3-3γ significantly reduced Bax expression, whereas knockdown of 14-3-3γ increased Bax in cortical neurons. Abolishing β-catenin phosphorylation at Ser37 (S37A) significantly reduced Bax and cell death in neurons upon OGD. Finally, 14-3-3γ overexpression completely suppressed β-catenin-enhanced Bax and cell death in neurons upon OGD. Based on these data, we propose that the 14-3-3γ/p-β-catenin Ser37/Bax axis determines cell survival or death of neurons during ischemia

  17. Signal enhancement ratio (SER) quantified from breast DCE-MRI and breast cancer risk

    NASA Astrophysics Data System (ADS)

    Wu, Shandong; Kurland, Brenda F.; Berg, Wendie A.; Zuley, Margarita L.; Jankowitz, Rachel C.; Sumkin, Jules; Gur, David

    2015-03-01

    Breast magnetic resonance imaging (MRI) is recommended as an adjunct to mammography for women who are considered at elevated risk of developing breast cancer. As a key component of breast MRI, dynamic contrast-enhanced MRI (DCE-MRI) uses a contrast agent to provide high intensity contrast between breast tissues, making it sensitive to tissue composition and vascularity. Breast DCE-MRI characterizes certain physiologic properties of breast tissue that are potentially related to breast cancer risk. Studies have shown that increased background parenchymal enhancement (BPE), which is the contrast enhancement occurring in normal cancer-unaffected breast tissues in post-contrast sequences, predicts increased breast cancer risk. Signal enhancement ratio (SER) computed from pre-contrast and post-contrast sequences in DCE-MRI measures change in signal intensity due to contrast uptake over time and is a measure of contrast enhancement kinetics. SER quantified in breast tumor has been shown potential as a biomarker for characterizing tumor response to treatments. In this work we investigated the relationship between quantitative measures of SER and breast cancer risk. A pilot retrospective case-control study was performed using a cohort of 102 women, consisting of 51 women who had diagnosed with unilateral breast cancer and 51 matched controls (by age and MRI date) with a unilateral biopsy-proven benign lesion. SER was quantified using fully-automated computerized algorithms and three SER-derived quantitative volume measures were compared between the cancer cases and controls using logistic regression analysis. Our preliminary results showed that SER is associated with breast cancer risk, after adjustment for the Breast Imaging Reporting and Data System (BI-RADS)-based mammographic breast density measures. This pilot study indicated that SER has potential for use as a risk factor for breast cancer risk assessment in women at elevated risk of developing breast cancer.

  18. Performance tuning non-uniform sampling for sensitivity enhancement of signal-limited biological NMR

    PubMed Central

    Palmer, Melissa R.; Wenrich, Broc R.; Stahlfeld, Phillip

    2014-01-01

    Non-uniform sampling (NUS) has been established as a route to obtaining true sensitivity enhancements when recording indirect dimensions of decaying signals in the same total experimental time as traditional uniform incrementation of the indirect evolution period. Theory and experiments have shown that NUS can yield up to two-fold improvements in the intrinsic signal-to-noise ratio (SNR) of each dimension, while even conservative protocols can yield 20–40 % improvements in the intrinsic SNR of NMR data. Applications of biological NMR that can benefit from these improvements are emerging, and in this work we develop some practical aspects of applying NUS nD-NMR to studies that approach the traditional detection limit of nD-NMR spectroscopy. Conditions for obtaining high NUS sensitivity enhancements are considered here in the context of enabling 1H,15N-HSQC experiments on natural abundance protein samples and 1H,13C-HMBC experiments on a challenging natural product. Through systematic studies we arrive at more precise guidelines to contrast sensitivity enhancements with reduced line shape constraints, and report an alternative sampling density based on a quarter-wave sinusoidal distribution that returns the highest fidelity we have seen to date in line shapes obtained by maximum entropy processing of non-uniformly sampled data. PMID:24682944

  19. Human engineering design considerations for the use of signal color enhancement in ASW displays

    SciTech Connect

    Banks, W.W.

    1990-11-01

    The Lawrence Livermore National Laboratory (LLNL) was requested to examine and define man-machine limits as part of the Office of Naval Technology's High Gain Initiative program (HGI). As an initial investigative area, LLNL's Systems and Human Performance effort focused upon color display interfaces and the use of color enhancement techniques to define human and system interface limits in signal detection and discrimination tasks. The knowledgeable and prudent use of color in different types of display is believed to facilitate human visual detection, discrimination and recognition in complex visual tasks. The consideration and understanding of the complex set of interacting variables associated with the prudent use of color is essential to optimize human performance, especially in the ASW community. The designers of advanced display technology and signal processing algorithms may be eventually called upon to present pre-processed information to ASW operators and researchers using the latest color enhancement techniques. These techniques, however, may be limited if one does not understand the complexity and limits of human information processing which reflects the assessed state of knowledge relevant to the use of color in displays. The initial sections of this report discuss various aspects of color presentation and the problems typically encountered, while the last section deals with a specific research proposal required to further our understanding and proper use of color enhancement methods.

  20. Enhancement of Raman scattering signal of a few molecules using photonic nanojet mediated SERS technique

    NASA Astrophysics Data System (ADS)

    Das, G. M.; Parit, M. K.; Laha, R.; Dantham, V. R.

    2016-05-01

    Now a days, single molecule surface enhanced Raman spectroscopy (SMSERS) has become a fascinating tool for studying the structural properties, static and dynamic events of single molecules (instead of ensemble average), with the help of efficient plasmonic nanostructures. This is extremely useful in the field of proteomics because the structural properties of protein molecules are heterogeneous. Even though, SMSERS provides wealthy information about single molecules, it demands high quality surface enhanced Raman scattering (SERS) substrates. So far, a very few researchers succeeded in demonstrating the single molecule Raman scattering using conventional SERS technique. However, the experimental S/N of the Raman signal has been found to be very poor. Recently, with the help of photonic nanojet of an optical microsphere, we were able to enhance the SERS signal of a few molecules adsorbed on the SERS substrates (gold symmetric and asymmetric nanodimers and trimers dispersed on a glass slide). Herein, we report a few details about photonic nanojet mediated SERS technique, a few experimental results and a detailed theoretical study on symmetric and asymmetric nanosphere dimers to understand the dependence of localised surface plasmon resonance (LSPR) wavelength of a nanodimer on the nanogap size and polarization of the excitation light.

  1. Inhibition of γ-secretase activity synergistically enhances tumour necrosis factor-related apoptosis-inducing ligand induced apoptosis in T-cell acute lymphoblastic leukemia cells via upregulation of death receptor 5

    PubMed Central

    Greene, Lisa M.; Nathwani, Seema M.; Zisterer, Daniela M.

    2016-01-01

    T-cell acute lymphoblastic leukemia (T-ALL) is a rare and aggressive hematopoietic malignancy prone to relapse and drug resistance. Half of all T-ALL patients exhibit mutations in Notch1, which leads to aberrant Notch1 associated signaling cascades. Notch1 activation is mediated by the γ-secretase cleavage of the Notch1 receptor into the active intracellular domain of Notch1 (NCID). Clinical trials of γ-secretase small molecule inhibitors (GSIs) as single agents for the treatment of T-ALL have been unsuccessful. The present study demonstrated, using immunofluorescence and western blotting, that blocking γ-secretase activity in T-ALL cells with N-[(3,5-difluorophenyl) acetyl]-L-alanyl-2-phenyl] glycine-1,1-dimethylethyl ester (DAPT) downregulated NCID and upregulated the tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) death receptor 5 (DR5). Upregulation of DR5 restored the sensitivity of T-ALL cells to TRAIL. Combination index revealed that the combined treatment of DAPT and TRAIL synergistically enhanced apoptosis compared with treatment with either drug alone. TRAIL combined with the clinically evaluated γ-secretase inhibitor 3-[(1r, 4s)-4-(4-chlorophenylsulfonyl)-4-(2, 5-difluorophenyl) cyclohexyl] propanoic acid (MK-0752) also significantly enhanced TRAIL-induced cell death compared with either drug alone. DAPT/TRAIL apoptotic synergy was dependent on the extrinsic apoptotic pathway and was associated with a decrease in BH3 interacting-domain death agonist and x-linked inhibitor of apoptosis. In conclusion, γ-secretase inhibition represents a potential therapeutic strategy to overcome TRAIL resistance for the treatment of T-ALL. PMID:27698877

  2. X-ROS signalling is enhanced and graded by cyclic cardiomyocyte stretch

    PubMed Central

    Prosser, Benjamin L.; Ward, Christopher W.; Lederer, W. Jonathan

    2013-01-01

    Aims A sustained, single stretch of a cardiomyocyte activates a transient production of reactive oxygen species by membrane-located NADPH oxidase 2 (Nox2). This NoX2-dependent ROS (X-ROS) tunes cardiac Ca2+ signalling by reversibly sensitizing sarcoplasmic reticulum Ca2+ release channels. In contrast to static length changes, working heart cells are cyclically stretched and shortened in the living animal. Additionally, this stretch cycle is constantly varied by changes in the pre-load and heart rate. Thus, the objective of this study was (i) to characterize X-ROS signalling during stretch-shortening cycles and (ii) to evaluate how the amplitude (pre-load) and frequency (heart rate) of cell stretch affects X-ROS and Ca2+ signalling. Methods and results Single adult rat cardiomyocytes were attached to MyoTak™-coated micro-rods and stretched, while ROS production and Ca2+ signals were monitored optically. Although a sustained stretch led to only a transient burst of ROS, cyclic stretch-shortening cycles led to a steady-state elevation of ROS production. Importantly, this new redox state was graded by both the amplitude of stretch (3–15%) and cycle frequency (1–4 Hz). Elevated ROS production enhanced Ca2+ signalling sensitivity as measured by the Ca2+ spark rate. Conclusion The steady-state level of ROS production in a cardiomyocyte is graded by the amplitude and frequency of cell stretch. Thus, mechanical changes that depend on the pre-load and heart rate regulate a dynamic redox balance that tunes cellular Ca2+ signalling. PMID:23524301

  3. Genotoxicity of ferric oxide nanoparticles in Raphanus sativus: Deciphering the role of signaling factors, oxidative stress and cell death.

    PubMed

    Saquib, Quaiser; Faisal, Mohammad; Alatar, Abdulrahman A; Al-Khedhairy, Abdulaziz A; Ahmed, Mukhtar; Ansari, Sabiha M; Alwathnani, Hend A; Okla, Mohammad K; Dwivedi, Sourabh; Musarrat, Javed; Praveen, Shelly; Khan, Shams T; Wahab, Rizwan; Siddiqui, Maqsood A; Ahmad, Javed

    2016-09-01

    We have studied the genotoxic and apoptotic potential of ferric oxide nanoparticles (Fe2O3-NPs) in Raphanus sativus (radish). Fe2O3-NPs retarded the root length and seed germination in radish. Ultrathin sections of treated roots showed subcellular localization of Fe2O3-NPs, along with the appearance of damaged mitochondria and excessive vacuolization. Flow cytometric analysis of Fe2O3-NPs (1.0mg/mL) treated groups exhibited 219.5%, 161%, 120.4% and 161.4% increase in intracellular reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), nitric oxide (NO) and Ca(2+) influx in radish protoplasts. A concentration dependent increase in the antioxidative enzymes glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) and lipid peroxidation (LPO) has been recorded. Comet assay showed a concentration dependent increase in deoxyribonucleic acid (DNA) strand breaks in Fe2O3-NPs treated groups. Cell cycle analysis revealed 88.4% of cells in sub-G1 apoptotic phase, suggesting cell death in Fe2O3-NPs (2.0mg/mL) treated group. Taking together, the genotoxicity induced by Fe2O3-NPs highlights the importance of environmental risk associated with improper disposal of nanoparticles (NPs) and radish can serve as a good indicator for measuring the phytotoxicity of NPs grown in NP-polluted environment.

  4. Caenorhabditis elegans SMA-10/LRIG is a conserved transmembrane protein that enhances bone morphogenetic protein signaling.

    PubMed

    Gumienny, Tina L; Macneil, Lesley; Zimmerman, Cole M; Wang, Huang; Chin, Lena; Wrana, Jeffrey L; Padgett, Richard W

    2010-05-20

    Bone morphogenetic protein (BMP) pathways control an array of developmental and homeostatic events, and must themselves be exquisitely controlled. Here, we identify Caenorhabditis elegans SMA-10 as a positive extracellular regulator of BMP-like receptor signaling. SMA-10 acts genetically in a BMP-like (Sma/Mab) pathway between the ligand DBL-1 and its receptors SMA-6 and DAF-4. We cloned sma-10 and show that it has fifteen leucine-rich repeats and three immunoglobulin-like domains, hallmarks of an LRIG subfamily of transmembrane proteins. SMA-10 is required in the hypodermis, where the core Sma/Mab signaling components function. We demonstrate functional conservation of LRIGs by rescuing sma-10(lf) animals with the Drosophila ortholog lambik, showing that SMA-10 physically binds the DBL-1 receptors SMA-6 and DAF-4 and enhances signaling in vitro. This interaction is evolutionarily conserved, evidenced by LRIG1 binding to vertebrate receptors. We propose a new role for LRIG family members: the positive regulation of BMP signaling by binding both Type I and Type II receptors.

  5. T-type Ca2+ channels are required for enhanced sympathetic axon growth by TNFα reverse signalling

    PubMed Central

    Kisiswa, Lilian; Erice, Clara; Ferron, Laurent; Wyatt, Sean; Osório, Catarina; Dolphin, Annette C.

    2017-01-01

    Tumour necrosis factor receptor 1 (TNFR1)-activated TNFα reverse signalling, in which membrane-integrated TNFα functions as a receptor for TNFR1, enhances axon growth from developing sympathetic neurons and plays a crucial role in establishing sympathetic innervation. Here, we have investigated the link between TNFα reverse signalling and axon growth in cultured sympathetic neurons. TNFR1-activated TNFα reverse signalling promotes Ca2+ influx, and highly selective T-type Ca2+ channel inhibitors, but not pharmacological inhibitors of L-type, N-type and P/Q-type Ca2+ channels, prevented enhanced axon growth. T-type Ca2+ channel-specific inhibitors eliminated Ca2+ spikes promoted by TNFα reverse signalling in axons and prevented enhanced axon growth when applied locally to axons, but not when applied to cell somata. Blocking action potential generation did not affect the effect of TNFα reverse signalling on axon growth, suggesting that propagated action potentials are not required for enhanced axon growth. TNFα reverse signalling enhanced protein kinase C (PKC) activation, and pharmacological inhibition of PKC prevented the axon growth response. These results suggest that TNFα reverse signalling promotes opening of T-type Ca2+ channels along sympathetic axons, which is required for enhanced axon growth. PMID:28100666

  6. Immune response and insulin signalling alter mosquito feeding behaviour to enhance malaria transmission potential

    PubMed Central

    Cator, Lauren J.; Pietri, Jose E.; Murdock, Courtney C.; Ohm, Johanna R.; Lewis, Edwin E.; Read, Andrew F.; Luckhart, Shirley; Thomas, Matthew B.

    2015-01-01

    Malaria parasites alter mosquito feeding behaviour in a way that enhances parasite transmission. This is widely considered a prime example of manipulation of host behaviour to increase onward transmission, but transient immune challenge in the absence of parasites can induce the same behavioural phenotype. Here, we show that alterations in feeding behaviour depend on the timing and dose of immune challenge relative to blood ingestion and that these changes are functionally linked to changes in insulin signalling in the mosquito gut. These results suggest that altered phenotypes derive from insulin signalling-dependent host resource allocation among immunity, blood feeding, and reproduction in a manner that is not specific to malaria parasite infection. We measured large increases in mosquito survival and subsequent transmission potential when feeding patterns are altered. Leveraging these changes in physiology, behaviour and life history could promote effective and sustainable control of female mosquitoes responsible for transmission. PMID:26153094

  7. Immune response and insulin signalling alter mosquito feeding behaviour to enhance malaria transmission potential.

    PubMed

    Cator, Lauren J; Pietri, Jose E; Murdock, Courtney C; Ohm, Johanna R; Lewis, Edwin E; Read, Andrew F; Luckhart, Shirley; Thomas, Matthew B

    2015-07-08

    Malaria parasites alter mosquito feeding behaviour in a way that enhances parasite transmission. This is widely considered a prime example of manipulation of host behaviour to increase onward transmission, but transient immune challenge in the absence of parasites can induce the same behavioural phenotype. Here, we show that alterations in feeding behaviour depend on the timing and dose of immune challenge relative to blood ingestion and that these changes are functionally linked to changes in insulin signalling in the mosquito gut. These results suggest that altered phenotypes derive from insulin signalling-dependent host resource allocation among immunity, blood feeding, and reproduction in a manner that is not specific to malaria parasite infection. We measured large increases in mosquito survival and subsequent transmission potential when feeding patterns are altered. Leveraging these changes in physiology, behaviour and life history could promote effective and sustainable control of female mosquitoes responsible for transmission.

  8. Identification of compounds that potentiate CREB signaling as possible enhancers of long-term memory

    PubMed Central

    Xia, Menghang; Huang, Ruili; Guo, Vicky; Southall, Noel; Cho, Ming-Hsuang; Inglese, James; Austin, Christopher P.; Nirenberg, Marshall

    2009-01-01

    Many studies have implicated the cAMP Response Element Binding (CREB) protein signaling pathway in long-term memory. To identify small molecule enhancers of CREB activation of gene expression, we screened ≈73,000 compounds, each at 7–15 concentrations in a quantitative high-throughput screening (qHTS) format, for activity in cells by assaying CREB mediated β-lactamase reporter gene expression. We identified 1,800 compounds that potentiated CREB mediated gene expression, with potencies as low as 16 nM, comprising 96 structural series. Mechanisms of action were systematically determined, and compounds that affect phosphodiesterase 4, protein kinase A, and cAMP production were identified, as well as compounds that affect CREB signaling via apparently unidentified mechanisms. qHTS folowed by interrogation of pathway targets is an efficient paradigm for lead generation for chemical genomics and drug development. PMID:19196967

  9. Bilirubin-induced inflammatory response, glutamate release, and cell death in rat cortical astrocytes are enhanced in younger cells.

    PubMed

    Falcão, Ana S; Fernandes, Adelaide; Brito, Maria A; Silva, Rui F M; Brites, Dora

    2005-11-01

    Unconjugated bilirubin (UCB) encephalopathy is a predominantly early life condition resulting from the impairment of several cellular functions in the brain of severely jaundiced infants. However, only few data exist on the age-dependent effects of UCB and their association with increased vulnerability of premature newborns, particularly in a sepsis condition. We investigated cell death, glutamate efflux, and inflammatory cytokine dynamics after exposure of astrocytes at different stages of differentiation to clinically relevant concentrations of UCB and/or lipopolysaccharide (LPS). Younger astrocytes were more prone to UCB-induced cell death, glutamate efflux, and inflammatory response than older ones. Furthermore, in immature cells, LPS exacerbated UCB effects, such as cell death by necrosis. These findings provide a basis for the increased susceptibility of premature newborns to UCB deleterious effects, namely when associated with sepsis, and underline how crucial the course of cell maturation can be to UCB encephalopathy during moderate to severe neonatal jaundice.

  10. 6-Shogaol Inhibits Breast Cancer Cells and Stem Cell-Like Spheroids by Modulation of Notch Signaling Pathway and Induction of Autophagic Cell Death.

    PubMed

    Ray, Anasuya; Vasudevan, Smreti; Sengupta, Suparna

    2015-01-01

    Cancer stem cells (CSCs) pose a serious obstacle to cancer therapy as they can be responsible for poor prognosis and tumour relapse. In this study, we have investigated inhibitory activity of the ginger-derived compound 6-shogaol against breast cancer cells both in monolayer and in cancer-stem cell-like spheroid culture. The spheroids were generated from adherent breast cancer cells. 6-shogaol was effective in killing both breast cancer monolayer cells and spheroids at doses that were not toxic to noncancerous cells. The percentages of CD44+CD24-/low cells and the secondary sphere content were reduced drastically upon treatment with 6-shogaol confirming its action on CSCs. Treatment with 6-shogaol caused cytoplasmic vacuole formation and cleavage of microtubule associated protein Light Chain3 (LC3) in both monolayer and spheroid culture indicating that it induced autophagy. Kinetic analysis of the LC3 expression and a combination treatment with chloroquine revealed that the autophagic flux instigated cell death in 6-shogaol treated breast cancer cells in contrast to the autophagy inhibitor chloroquine. Furthermore, 6-shogaol-induced cell death got suppressed in the presence of chloroquine and a very low level of apoptosis was exhibited even after prolonged treatment of the compound, suggesting that autophagy is the major mode of cell death induced by 6-shogaol in breast cancer cells. 6-shogaol reduced the expression levels of Cleaved Notch1 and its target proteins Hes1 and Cyclin D1 in spheroids, and the reduction was further pronounced in the presence of a γ-secretase inhibitor. Secondary sphere formation in the presence of the inhibitor was also further reduced by 6-shogaol. Together, these results indicate that the inhibitory action of 6-shogaol on spheroid growth and sustainability is conferred through γ-secretase mediated down-regulation of Notch signaling. The efficacy of 6-shogaol in monolayer and cancer stem cell-like spheroids raise hope for its

  11. Ginkgo biloba extract EGb761 attenuates brain death-induced renal injury by inhibiting pro-inflammatory cytokines and the SAPK and JAK-STAT signalings

    PubMed Central

    Li, Yifu; Xiong, Yunyi; Zhang, Huanxi; Li, Jun; Wang, Dong; Chen, Wenfang; Yuan, Xiaopeng; Su, Qiao; Li, Wenwen; Huang, Huiting; Bi, Zirong; Liu, Longshan; Wang, Changxi

    2017-01-01

    This study aimed to investigate the protective effects of EGb761, a Ginkgo Biloba extract, against brain death-induced kidney injury. Sixty male Sprague Dawley rats were randomly divided into six groups: sham, brain-death (BD), BD + EGb b48h (48 hours before BD), BD + EGb 2 h (2 hours after BD), BD + EGb 1 h, and BD + EGb 0.5 h. Six hours after BD, serum sample and kidney tissues were collected for analyses. The levels of blood urea nitrogen (BUN) and serum creatinine significantly elevated in the BD group than in sham group. In all the EGb761-treated BD animals except for the BD + Gb 2 h group, the levels of BUN and serum creatinine significantly reduced (all P < 0.01). EGb761 attenuated tubular injury and lowered the histological score. In addition, the longer duration of drug treatment was, the better protective efficacy could be observed. EGb761 significantly reduced IL-1β, IL-6, TNF-α, MCP-1, IP-10 mRNA expression and macrophage infiltration in the kidney. EGb761 treatment at 48 hour before brain death significantly attenuate the levels of p-JNK-MAPK, p-p38-MAPK, and p-STAT3 proteins (all P < 0.05, compared to BD group). In summary, our data showed that EGb761 treatment protected donor kidney from BD-induced damages by blocking SAPK and JAK-STAT signalings. Early administration of EGb761 can provide better protective efficacy. PMID:28332628

  12. 6-Shogaol Inhibits Breast Cancer Cells and Stem Cell-Like Spheroids by Modulation of Notch Signaling Pathway and Induction of Autophagic Cell Death

    PubMed Central

    Ray, Anasuya; Vasudevan, Smreti; Sengupta, Suparna

    2015-01-01

    Cancer stem cells (CSCs) pose a serious obstacle to cancer therapy as they can be responsible for poor prognosis and tumour relapse. In this study, we have investigated inhibitory activity of the ginger-derived compound 6-shogaol against breast cancer cells both in monolayer and in cancer-stem cell-like spheroid culture. The spheroids were generated from adherent breast cancer cells. 6-shogaol was effective in killing both breast cancer monolayer cells and spheroids at doses that were not toxic to noncancerous cells. The percentages of CD44+CD24-/low cells and the secondary sphere content were reduced drastically upon treatment with 6-shogaol confirming its action on CSCs. Treatment with 6-shogaol caused cytoplasmic vacuole formation and cleavage of microtubule associated protein Light Chain3 (LC3) in both monolayer and spheroid culture indicating that it induced autophagy. Kinetic analysis of the LC3 expression and a combination treatment with chloroquine revealed that the autophagic flux instigated cell death in 6-shogaol treated breast cancer cells in contrast to the autophagy inhibitor chloroquine. Furthermore, 6-shogaol-induced cell death got suppressed in the presence of chloroquine and a very low level of apoptosis was exhibited even after prolonged treatment of the compound, suggesting that autophagy is the major mode of cell death induced by 6-shogaol in breast cancer cells. 6-shogaol reduced the expression levels of Cleaved Notch1 and its target proteins Hes1 and Cyclin D1 in spheroids, and the reduction was further pronounced in the presence of a γ-secretase inhibitor. Secondary sphere formation in the presence of the inhibitor was also further reduced by 6-shogaol. Together, these results indicate that the inhibitory action of 6-shogaol on spheroid growth and sustainability is conferred through γ-secretase mediated down-regulation of Notch signaling. The efficacy of 6-shogaol in monolayer and cancer stem cell-like spheroids raise hope for its

  13. Cadmium exposure activates the ERK signaling pathway leading to altered osteoblast gene expression and apoptotic death in Saos-2 cells.

    PubMed

    Arbon, Kate S; Christensen, Cody M; Harvey, Wendy A; Heggland, Sara J

    2012-02-01

    Recent reports of cadmium in electronic waste and jewelry have increased public awareness regarding this toxic metal. Human exposure to cadmium is associated with the development of osteoporosis. We previously reported cadmium induces apoptosis in human tumor-derived Saos-2 osteoblasts. In this study, we examine the extracellular signal-regulated protein kinase (ERK) and protein kinase C (PKC) pathways in cadmium-induced apoptosis and altered osteoblast gene expression. Saos-2 osteoblasts were cultured in the presence or absence of 10μM CdCl(2) for 2-72h. We detected significant ERK activation in response to CdCl(2) and pretreatment with the ERK inhibitor PD98059 attenuated cadmium-induced apoptosis. However, PKCα activation was not observed after exposure to CdCl(2) and pretreatment with the PKC inhibitor, Calphostin C, was unable to rescue cells from cadmium-induced apoptosis. Gene expression studies were conducted using qPCR. Cells exposed to CdCl(2) exhibited a significant decrease in the bone-forming genes osteopontin (OPN) and alkaline phosphatase (ALP) mRNA. In contrast, SOST, whose protein product inhibits bone formation, significantly increased in response to CdCl(2). Pretreatment with PD98059 had a recovery effect on cadmium-induced changes in gene expression. This research demonstrates cadmium can directly inhibit osteoblasts via ERK signaling pathway and identifies SOST as a target for cadmium-induced osteotoxicity.

  14. Homocysteine enhances MMP-9 production in murine macrophages via ERK and Akt signaling pathways

    SciTech Connect

    Lee, Seung Jin; Lee, Yi Sle; Seo, Kyo Won; Bae, Jin Ung; Kim, Gyu Hee; Park, So Youn; Kim, Chi Dae

    2012-04-01

    Homocysteine (Hcy) at elevated levels is an independent risk factor of cardiovascular diseases, including atherosclerosis. In the present study, we investigated the effect of Hcy on the production of matrix metalloproteinases (MMP) in murine macrophages. Among the MMP known to regulate the activities of collagenase and gelatinase, Hcy exclusively increased the gelatinolytic activity of MMP-9 in J774A.1 cells as well as in mouse peritoneal macrophages. Furthermore, this activity was found to be correlated with Western blot findings in J774A.1 cells, which showed that MMP-9 expression was concentration- and time-dependently increased by Hcy. Inhibition of the ERK and Akt pathways led to a significant decrease in Hcy-induced MMP-9 expression, and combined treatment with inhibitors of the ERK and Akt pathways showed an additive effects. Activity assays for ERK and Akt showed that Hcy increased the phosphorylation of both, but these phosphorylation were not affected by inhibitors of the Akt and ERK pathways. In line with these findings, the molecular inhibition of ERK and Akt using siRNA did not affect the Hcy-induced phosphorylation of Akt and ERK, respectively. Taken together, these findings suggest that Hcy enhances MMP-9 production in murine macrophages by separately activating the ERK and Akt signaling pathways. -- Highlights: ► Homocysteine (Hcy) induced MMP-9 production in murine macrophages. ► Hcy induced MMP-9 production through ERK and Akt signaling pathways. ► ERK and Akt signaling pathways were activated by Hcy in murine macrophages. ► ERK and Akt pathways were additively act on Hcy-induced MMP-9 production. ► Hcy enhances MMP-9 production in macrophages via activation of ERK and Akt signaling pathways in an independent manner.

  15. UVB Radiation-Induced β-catenin Signaling is Enhanced by COX-2 Expression in Keratinocytes

    PubMed Central

    Smith, Kimberly A.; Tong, Xin; Abu-Yousif, Adnan O.; Mikulec, Carol C.; Gottardi, Cara J.; Fischer, Susan M.; Pelling, Jill C.

    2014-01-01

    UVB radiation is the major carcinogen responsible for skin carcinogenesis, thus elucidation of the molecular pathways altered in skin in response to UVB would reveal novel targets for therapeutic intervention. It is well established that UVB leads to upregulation of cyclooxygenase 2 (COX-2) in the skin which contributes to skin carcinogenesis. Overexpression of COX-2 has been shown to promote colon cancer cell growth through β-catenin signaling, however, little is known about the connection between UVB, COX-2 and β-catenin in the skin. In the present study, we have identified a novel pathway in which UVB induces β-catenin signaling in keratinocytes, which is modulated by COX-2 expression. Exposure of the mouse 308 keratinocyte cell line (308 cells) and primary normal human epidermal keratinocytes (NHEKs) to UVB resulted in increased protein levels of both N-terminally unphosphorylated and total β-catenin. In addition, we found that UVB enhanced β-catenin-dependent TOPflash reporter activity and expression of a downstream β-catenin target gene. We demonstrated that UVB-induced β-catenin signaling is modulated by COX-2, as treatment of keratinocytes with the specific COX-2 inhibitor NS398 blocked UVB induction of β-catenin. Additionally, β-catenin target gene expression was reduced in UVB-treated COX-2 knockout (KO) MEFs compared to wild-type (WT) MEFs. Furthermore, epidermis from UVB-exposed SKH-1 mice exhibited increased N-terminally unphosphorylated and total β-catenin protein levels and increased staining for total β-catenin, and both responses were reduced in COX-2 heterozygous mice. Taken together, these results suggest a novel pathway in which UVB induces β-catenin signaling in keratinocytes which is enhanced by COX-2 expression. PMID:21853475

  16. LL37 and Cationic Peptides Enhance TLR3 Signaling by Viral Double-stranded RNAs

    PubMed Central

    Lai, Yvonne; Adhikarakunnathu, Sreedevi; Bhardwaj, Kanchan; Ranjith-Kumar, C. T.; Wen, Yahong; Jordan, Jarrat L.; Wu, Linda H.; Dragnea, Bogdan; Mateo, Lani San; Kao, C. Cheng

    2011-01-01

    Background Toll-like Receptor 3 (TLR3) detects viral dsRNA during viral infection. However, most natural viral dsRNAs are poor activators of TLR3 in cell-based systems, leading us to hypothesize that TLR3 needs additional factors to be activated by viral dsRNAs. The anti-microbial peptide LL37 is the only known human member of the cathelicidin family of anti-microbial peptides. LL37 complexes with bacterial lipopolysaccharide (LPS) to prevent activation of TLR4, binds to ssDNA to modulate TLR9 and ssRNA to modulate TLR7 and 8. It synergizes with TLR2/1, TLR3 and TLR5 agonists to increase IL8 and IL6 production. This work seeks to determine whether LL37 enhances viral dsRNA recognition by TLR3. Methodology/Principal Findings Using a human bronchial epithelial cell line (BEAS2B) and human embryonic kidney cells (HEK 293T) transiently transfected with TLR3, we found that LL37 enhanced poly(I:C)-induced TLR3 signaling and enabled the recognition of viral dsRNAs by TLR3. The presence of LL37 also increased the cytokine response to rhinovirus infection in BEAS2B cells and in activated human peripheral blood mononuclear cells. Confocal microscopy determined that LL37 could co-localize with TLR3. Electron microscopy showed that LL37 and poly(I:C) individually formed globular structures, but a complex of the two formed filamentous structures. To separate the effects of LL37 on TLR3 and TLR4, other peptides that bind RNA and transport the complex into cells were tested and found to activate TLR3 signaling in response to dsRNAs, but had no effect on TLR4 signaling. This is the first demonstration that LL37 and other RNA-binding peptides with cell penetrating motifs can activate TLR3 signaling and facilitate the recognition of viral ligands. Conclusions/Significance LL37 and several cell-penetrating peptides can enhance signaling by TLR3 and enable TLR3 to respond to viral dsRNA. PMID:22039520

  17. Surface-enhanced Raman signal for terbium single-molecule magnets grafted on graphene.

    PubMed

    Lopes, Manuel; Candini, Andrea; Urdampilleta, Matias; Reserbat-Plantey, Antoine; Bellini, Valerio; Klyatskaya, Svetlana; Marty, Laëtitia; Ruben, Mario; Affronte, Marco; Wernsdorfer, Wolfgang; Bendiab, Nedjma

    2010-12-28

    We report the preparation and characterization of monolayer graphene decorated with functionalized single-molecule magnets (SMMs). The grafting ligands provide a homogeneous and selective deposition on graphene. The grafting is characterized by combined Raman microspectroscopy, atomic force microscopy (AFM), and electron transport measurements. We observe a surface-enhanced Raman signal that allowed us to study the grafting down to the limit of a few isolated molecules. The weak interaction through charge transfer is in agreement with ab initio DFT calculations. Our results indicate that both molecules and graphene are essentially intact and the interaction is driven by van der Waals forces.

  18. Enhancement of single-molecule fluorescence signals by colloidal silver nanoparticles in studies of protein translation.

    PubMed

    Bharill, Shashank; Chen, Chunlai; Stevens, Benjamin; Kaur, Jaskiran; Smilansky, Zeev; Mandecki, Wlodek; Gryczynski, Ignacy; Gryczynski, Zygmunt; Cooperman, Barry S; Goldman, Yale E

    2011-01-25

    Metal-enhanced fluorescence (MEF) increased total photon emission of Cy3- and Cy5-labeled ribosomal initiation complexes near 50 nm silver particles 4- and 5.5-fold, respectively. Fluorescence intensity fluctuations above shot noise, at 0.1-5 Hz, were greater on silver particles. Overall signal-to-noise ratio was similar or slightly improved near the particles. Proximity to silver particles did not compromise ribosome function, as measured by codon-dependent binding of fluorescent tRNA, dynamics of fluorescence resonance energy transfer between adjacent tRNAs in the ribosome, and tRNA translocation induced by elongation factor G.

  19. Thermally enhanced signal strength and SNR improvement of photoacoustic radar module

    PubMed Central

    Wang, Wei; Mandelis, Andreas

    2014-01-01

    A thermally enhanced method for improving photoacoustic imaging depth and signal-to-noise (SNR) ratio is presented in this paper. Experimental results showed that the maximum imaging depth increased by 20% through raising the temperature of absorbing biotissues (ex-vivo beef muscle) uniformly from 37 to 43°C, and the SNR was increased by 8%. The parameters making up the Gruneisen constant were investigated experimentally and theoretically. The studies showed that the Gruneisen constant of biotissues increases with temperature, and the results were found to be consistent with the photoacousitc radar theory. PMID:25136501

  20. Signal enhancement of surface plasmon resonance based on gold nanoparticle-antibody complex for immunoassay.

    PubMed

    Lee, Woochang; Oh, Byung-Keun; Kim, Yong-Wan; Choi, Jeong-Woo

    2006-11-01

    In the immunoassay based on surface plasmon resonance (SPR) system, the signal enhancement was done by means of the conjugate of gold (Au) nanoparticle-antibody fragment. Antibody fragment was prepared for the improved immobilization based on Au-thiol interaction. Through the ellipsometric analysis on surface, the conjugation between Au and antibody fragment was performed in the oriented manner. The optimal fabrication conditions such as concentration and incubation time were determined for the constant size of the fabricated nanoparticle-antibody conjugate. Through the plot of SPR angle difference versus antigen concentration, the linear correlation was achieved, of which the detection limit was 100 fg/ml.

  1. Cutting Edge: Molecular Structure of the IL-1R-Associated Kinase-4 Death Domain and Its Implications for TLR Signaling

    SciTech Connect

    Lasker, Michael V.; Gajjar, Mark M.; Nair, Satish K.

    2010-07-19

    IL-1R-associated kinase (IRAK) 4 is an essential component of innate immunity. IRAK-4 deficiency in mice and humans results in severe impairment of IL-1 and TLR signaling. We have solved the crystal structure for the death domain of Mus musculus IRAK-4 to 1.7 {angstrom} resolution. This is the first glimpse of the structural details of a mammalian IRAK family member. The crystal structure reveals a six-helical bundle with a prominent loop, which among IRAKs and Pelle, a Drosophila homologue, is unique to IRAK-4. This highly structured loop contained between helices two and three, comprises an 11-aa stretch. Although innate immune domain recognition is thought to be very similar between Drosophila and mammals, this structural component points to a drastic difference. This structure can be used as a framework for future mutation and deletion studies and potential drug design.

  2. Signal enhancement of surface plasmon-coupled directional emission by a conical mirror.

    PubMed

    Smith, Derek S; Kostov, Yordan; Rao, Govind

    2008-10-01

    A simple strategy for increasing the collection efficiency of surface plasmon-coupled emission (SPCE) is demonstrated. SPCE is a near-field phenomenon occurring when excited fluorophores are in close proximity to a subwavelength metal film. The energy of the fluorophores induces surface plasmons that radiate the coupled energy at highly specific angles. In an attempt to maximize the collected emission, a conical mirror was placed around the coupling prism. The result was a nearly 500 fold enhancement over the free space signal as detected from a single point from a poly(vinyl alcohol) layer doped with ruthenium. Coupling this large enhancement with LED excitation could lead to the development of inexpensive, handheld fluorescent devices with high sensitivity.

  3. Attention enhances synaptic efficacy and the signal-to-noise ratio in neural circuits.

    PubMed

    Briggs, Farran; Mangun, George R; Usrey, W Martin

    2013-07-25

    Attention is a critical component of perception. However, the mechanisms by which attention modulates neuronal communication to guide behaviour are poorly understood. To elucidate the synaptic mechanisms of attention, we developed a sensitive assay of attentional modulation of neuronal communication. In alert monkeys performing a visual spatial attention task, we probed thalamocortical communication by electrically stimulating neurons in the lateral geniculate nucleus of the thalamus while simultaneously recording shock-evoked responses from monosynaptically connected neurons in primary visual cortex. We found that attention enhances neuronal communication by increasing the efficacy of presynaptic input in driving postsynaptic responses, by increasing synchronous responses among ensembles of postsynaptic neurons receiving independent input, and by decreasing redundant signals between postsynaptic neurons receiving common input. The results demonstrate that attention finely tunes neuronal communication at the synaptic level by selectively altering synaptic weights, enabling enhanced detection of salient events in the noisy sensory environment.

  4. Calcium-mediated repression of β-catenin and its transcriptional signaling mediates neural crest cell death in an avian model of fetal alcohol syndrome.

    PubMed

    Flentke, George R; Garic, Ana; Amberger, Ed; Hernandez, Marcos; Smith, Susan M

    2011-07-01

    Fetal alcohol syndrome (FAS) is a common birth defect in many societies. Affected individuals have neurodevelopmental disabilities and a distinctive craniofacial dysmorphology. These latter deficits originate during early development from the ethanol-mediated apoptotic depletion of cranial facial progenitors, a population known as the neural crest. We showed previously that this apoptosis is caused because acute ethanol exposure activates G-protein-dependent intracellular calcium within cranial neural crest progenitors, and this calcium transient initiates the cell death. The dysregulated signals that reside downstream of ethanol's calcium transient and effect neural crest death are unknown. Here we show that ethanol's repression of the transcriptional effector β-catenin causes the neural crest losses. Clinically relevant ethanol concentrations (22-78 mM) rapidly deplete nuclear β-catenin from neural crest progenitors, with accompanying losses of β-catenin transcriptional activity and downstream genes that govern neural crest induction, expansion, and survival. Using forced expression studies, we show that β-catenin loss of function (via dominant-negative T cell transcription factor [TCF]) recapitulates ethanol's effects on neural crest apoptosis, whereas β-catenin gain-of-function in ethanol's presence preserves neural crest survival. Blockade of ethanol's calcium transient using Bapta-AM normalizes β-catenin activity and prevents the neural crest losses, whereas ionomycin treatment is sufficient to destabilize β-catenin. We propose that ethanol's repression of β-catenin causes the neural crest losses in this model of FAS. β-Catenin is a novel target for ethanol's teratogenicity. β-Catenin/Wnt signals participate in many developmental events and its rapid and persistent dysregulation by ethanol may explain why the latter is such a potent teratogen.

  5. Collision-induced signal enhancement (CISE): the use of boundary activation to effect non-resonant CISE.

    PubMed

    Asam, Michael R; Glish, Gary L

    2002-06-01

    An alternative to resonant excitation collision-induced signal enhancement (CISE) is presented. This alternative utilizes boundary activation instead of resonant excitation to effect CISE and is called boundary activated collision induced signal enhancement (BA-CISE). There are three ways to effect BA-CISE to enhance the signal for an MS(n+1) experiment. Each technique utilizes the beta(z) = 0 boundary, which ions encounter from high to low mass/charge ratio. BA-CISE is shown to produce an almost 900% increase in the C2 ion of [maltohexaose + Li]+. The use of a heavy collision gas in addition to the helium bath gas generally produced a signal enhancement inferior to the same experiment without the heavy gas.

  6. Combination Treatment with Sublethal Ionizing Radiation and the Proteasome Inhibitor, Bortezomib, Enhances Death-Receptor Mediated Apoptosis and Anti-Tumor Immune Attack

    PubMed Central

    Cacan, Ercan; Spring, Alexander M.; Kumari, Anita; Greer, Susanna F.; Garnett-Benson, Charlie

    2015-01-01

    Sub-lethal doses of radiation can modulate gene expression, making tumor cells more susceptible to T-cell-mediated immune attack. Proteasome inhibitors demonstrate broad anti-tumor activity in clinical and pre-clinical cancer models. Here, we use a combination treatment of proteasome inhibition and irradiation to further induce immunomodulation of tumor cells that could enhance tumor-specific immune responses. We investigate the effects of the 26S proteasome inhibitor, bortezomib, alone or in combination with radiotherapy, on the expression of immunogenic genes in normal colon and colorectal cancer cell lines. We examined cells for changes in the expression of several death receptors (DR4, DR5 and Fas) commonly used by T cells for killing of target cells. Our results indicate that the combination treatment resulted in increased cell surface expression of death receptors by increasing their transcript levels. The combination treatment further increases the sensitivity of carcinoma cells to apoptosis through FAS and TRAIL receptors but does not change the sensitivity of normal non-malignant epithelial cells. Furthermore, the combination treatment significantly enhances tumor cell killing by tumor specific CD8+ T cells. This study suggests that combining radiotherapy and proteasome inhibition may simultaneously enhance tumor immunogenicity and the induction of antitumor immunity by enhancing tumor-specific T-cell activity. PMID:26703577

  7. Accumulation of Phosphorylated β-Catenin Enhances ROS-Induced Cell Death in Presenilin-Deficient Cells

    PubMed Central

    Boo, Jung H.; Song, Hyundong; Kim, Ji E.; Kang, David E.; Mook-Jung, Inhee

    2009-01-01

    Presenilin (PS) is involved in many cellular events under physiological and pathological conditions. Previous reports have revealed that PS deficiency results in hyperproliferation and resistance to apoptotic cell death. In the present study, we investigated the effects of PS on β-catenin and cell mortality during serum deprivation. Under these conditions, PS1/PS2 double-knockout MEFs showed aberrant accumulation of phospho-β-catenin, higher ROS generation, and notable cell death. Inhibition of β-catenin phosphorylation by LiCl reversed ROS generation and cell death in PS deficient cells. In addition, the K19/49R mutant form of β-catenin, which undergoes normal phosphorylation but not ubiquitination, induced cytotoxicity, while the phosphorylation deficient S37A β-catenin mutant failed to induce cytotoxicity. These results indicate that aberrant accumulation of phospho-β-catenin underlies ROS-mediated cell death in the absence of PS. We propose that the regulation of β-catenin is useful for identifying therapeutic targets of hyperproliferative diseases and other degenerative conditions. PMID:19137062

  8. A data-driven method to enhance vibration signal decomposition for rolling bearing fault analysis

    NASA Astrophysics Data System (ADS)

    Grasso, M.; Chatterton, S.; Pennacchi, P.; Colosimo, B. M.

    2016-12-01

    Health condition analysis and diagnostics of rotating machinery requires the capability of properly characterizing the information content of sensor signals in order to detect and identify possible fault features. Time-frequency analysis plays a fundamental role, as it allows determining both the existence and the causes of a fault. The separation of components belonging to different time-frequency scales, either associated to healthy or faulty conditions, represents a challenge that motivates the development of effective methodologies for multi-scale signal decomposition. In this framework, the Empirical Mode Decomposition (EMD) is a flexible tool, thanks to its data-driven and adaptive nature. However, the EMD usually yields an over-decomposition of the original signals into a large number of intrinsic mode functions (IMFs). The selection of most relevant IMFs is a challenging task, and the reference literature lacks automated methods to achieve a synthetic decomposition into few physically meaningful modes by avoiding the generation of spurious or meaningless modes. The paper proposes a novel automated approach aimed at generating a decomposition into a minimal number of relevant modes, called Combined Mode Functions (CMFs), each consisting in a sum of adjacent IMFs that share similar properties. The final number of CMFs is selected in a fully data driven way, leading to an enhanced characterization of the signal content without any information loss. A novel criterion to assess the dissimilarity between adjacent CMFs is proposed, based on probability density functions of frequency spectra. The method is suitable to analyze vibration signals that may be periodically acquired within the operating life of rotating machineries. A rolling element bearing fault analysis based on experimental data is presented to demonstrate the performances of the method and the provided benefits.

  9. Tim-3 enhances FcεRI-proximal signaling to modulate mast cell activation.

    PubMed

    Phong, Binh L; Avery, Lyndsay; Sumpter, Tina L; Gorman, Jacob V; Watkins, Simon C; Colgan, John D; Kane, Lawrence P

    2015-12-14

    T cell (or transmembrane) immunoglobulin and mucin domain protein 3 (Tim-3) has attracted significant attention as a novel immune checkpoint receptor (ICR) on chronically stimulated, often dysfunctional, T cells. Antibodies to Tim-3 can enhance antiviral and antitumor immune responses. Tim-3 is also constitutively expressed by mast cells, NK cells and specific subsets of macrophages and dendritic cells. There is ample evidence for a positive role for Tim-3 in these latter cell types, which is at odds with the model of Tim-3 as an inhibitory molecule on T cells. At this point, little is known about the molecular mechanisms by which Tim-3 regulates the function of T cells or other cell types. We have focused on defining the effects of Tim-3 ligation on mast cell activation, as these cells constitutively express Tim-3 and are activated through an ITAM-containing receptor for IgE (FcεRI), using signaling pathways analogous to those in T cells. Using a variety of gain- and loss-of-function approaches, we find that Tim-3 acts at a receptor-proximal point to enhance Lyn kinase-dependent signaling pathways that modulate both immediate-phase degranulation and late-phase cytokine production downstream of FcεRI ligation.

  10. Signal enhancement in laser-induced breakdown spectroscopy using fast square-pulse discharges

    NASA Astrophysics Data System (ADS)

    Sobral, H.; Robledo-Martinez, A.

    2016-10-01

    A fast, high voltage square-shaped electrical pulse initiated by laser ablation was investigated as a means to enhance the analytical capabilities of laser Induced breakdown spectroscopy (LIBS). The electrical pulse is generated by the discharge of a charged coaxial cable into a matching impedance. The pulse duration and the stored charge are determined by the length of the cable. The ablation plasma was produced by hitting an aluminum target with a nanosecond 532-nm Nd:YAG laser beam under variable fluence 1.8-900 J cm- 2. An enhancement of up to one order of magnitude on the emission signal-to-noise ratio can be achieved with the spark discharge assisted laser ablation. Besides, this increment is larger for ionized species than for neutrals. LIBS signal is also increased with the discharge voltage with a tendency to saturate for high laser fluences. Electron density and temperature evolutions were determined from time delays of 100 ns after laser ablation plasma onset. Results suggest that the spark discharge mainly re-excites the laser produced plume.

  11. Berberine augments ATP-induced inflammasome activation in macrophages by enhancing AMPK signaling

    PubMed Central

    Xu, Li-Hui; Liang, Yi-Dan; Wei, Hong-Xia; Hu, Bo; Pan, Hao; Zha, Qing-Bing; Ouyang, Dong-Yun; He, Xian-Hui

    2017-01-01

    The isoquinoline alkaloid berberine possesses many pharmacological activities including antibacterial infection. Although the direct bactericidal effect of berberine has been documented, its influence on the antibacterial functions of macrophages is largely unknown. As inflammasome activation in macrophages is important for the defense against bacterial infection, we aimed to investigate the influence of berberine on inflammasome activation in murine macrophages. Our results showed that berberine significantly increased ATP-induced inflammasome activation as reflected by enhanced pyroptosis as well as increased release of caspase-1p10 and mature interleukin-1β (IL-1β) in macrophages. Such effects of berberine could be suppressed by AMP-activated protein kinase (AMPK) inhibitor compound C or by knockdown of AMPKα expression, indicating the involvement of AMPK signaling in this process. In line with increased IL-1β release, the ability of macrophages to kill engulfed bacteria was also intensified by berberine. This was corroborated by the in vivo finding that the peritoneal live bacterial load was decreased by berberine treatment. Moreover, berberine administration significantly improved survival of bacterial infected mice, concomitant with increased IL-1β levels and elevated neutrophil recruitment in the peritoneal cavity. Collectively, these data suggested that berberine could enhance bacterial killing by augmenting inflammasome activation in macrophages through AMPK signaling. PMID:27980220

  12. Binding and signalling properties of a growth hormone enhancing monoclonal antibody.

    PubMed

    Beattie, J; Bramani, S; Secchi, C; Mockridge, J

    1999-08-01

    We have used a sequential, qualitative biosensor based assay to demonstrate that OA15, a monoclonal antibody which enhances in vivo the activity of bovine growth hormone (bGH) does not disrupt the interaction between bGH and its cognate receptor (as represented by recombinant bovine GH binding protein -rbGHBP). We have confirmed this using a classical cell-based radio-receptor assay with the GH-responsive mouse pre-adipocyte cell line 3T3-F442A. The fact that OA 15 binding to bGH still allows hormone to interact with its receptor, allows us to test the hypothesis that there is any amplification of signalling events following hormone-MAb treatment of 3T3-F442A cells. We have used as a reporter of GH activity the rapid stimulation of JAK-2 tyrosine phosphorylation which is a critical first step in GH signalling events. We demonstrate that binding of rbGH by OA15 attenuates hormone stimulation of JAK-2 tyrosine phosphorylation. We conclude that although OA15 does not disrupt GH-GH receptor (GHR) interactions it does interfere with subsequent GH activity at the molecular and cellular level. We further speculate therefore that the biological enhancing activity of this antibody is most likely due to an in vivo effect as presentation of antibody-hormone complexes to a GH-target cell inhibits hormone activity.

  13. Tim-3 enhances FcεRI-proximal signaling to modulate mast cell activation

    PubMed Central

    Phong, Binh L.; Avery, Lyndsay; Sumpter, Tina L.; Gorman, Jacob V.; Watkins, Simon C.; Colgan, John D.

    2015-01-01

    T cell (or transmembrane) immunoglobulin and mucin domain protein 3 (Tim-3) has attracted significant attention as a novel immune checkpoint receptor (ICR) on chronically stimulated, often dysfunctional, T cells. Antibodies to Tim-3 can enhance antiviral and antitumor immune responses. Tim-3 is also constitutively expressed by mast cells, NK cells and specific subsets of macrophages and dendritic cells. There is ample evidence for a positive role for Tim-3 in these latter cell types, which is at odds with the model of Tim-3 as an inhibitory molecule on T cells. At this point, little is known about the molecular mechanisms by which Tim-3 regulates the function of T cells or other cell types. We have focused on defining the effects of Tim-3 ligation on mast cell activation, as these cells constitutively express Tim-3 and are activated through an ITAM-containing receptor for IgE (FcεRI), using signaling pathways analogous to those in T cells. Using a variety of gain- and loss-of-function approaches, we find that Tim-3 acts at a receptor-proximal point to enhance Lyn kinase-dependent signaling pathways that modulate both immediate-phase degranulation and late-phase cytokine production downstream of FcεRI ligation. PMID:26598760

  14. Ultrasound signal processing for characterization and enhanced biometry of the cornea

    NASA Astrophysics Data System (ADS)

    Silverman, Ronald H.; Reinstein, Dan Z.; Lizzi, Frederick L.; Coleman, D. J.

    2001-05-01

    Purpose: The cornea acts as the window of the eye's optical system, and its chief refractive component. The lack of intervening tissues makes the cornea accessible to very high frequency ultrasonic study. In this report, we detail use of radiofrequency (RF) signal processing methods to characterize corneal pathology and to enhance biometric precision. Methods: Using a 50 MHz PVDF transducer, we scanned the cornea using an arc motion so as to maintain normality and consistent range. RF data were acquired at a sample rate of 500 MHz. Deconvolution against a glass-plate echo allowed biometric enhancement (by effectively broadening the bandwidth) and measurement of tissue backscatter spectra. Results: Calibrated spectrum analysis was used to quantitatively measure backscatter in corneal scars and other pathologies. Signal processing allowed us to attain reproducibility for repeated measurements of the corneal epithelium (approximately 50 microns thick) to 1 micron. By combining measurements from a series of planes, maps of the thickness of the individual layers comprising the cornea were produced. Conclusion: The layers of the cornea have different optical refractive indices, and thus their thicknesses directly affect visual acuity. The scattering of light by a corneal scar is caused by inhomogeneities or irregularities that may result in acoustic backscatter as well. The ability of ultrasound to quantify backscatter and corneal layer thickness provides a new avenue for diagnosis of corneal disease and refractive abnormalities.

  15. InSAR Reveals a Potpourri of Deformation Signals in the Yucca Mountain -- Amargosa Valley -- Death Valley Region, Southwestern Nevada/Southeastern California

    NASA Astrophysics Data System (ADS)

    Katzenstein, K. W.; Bell, J. W.

    2005-12-01

    InSAR studies have revealed a variety of surface deformation signals attributed to several causes in the Yucca Mountain -- Amargosa Valley -- Death Valley region. This study utilizes 26 ERS 1 and 2 scenes to produce 34 interferometric pairs that cover the period of 1992 - 2000. Prominent signals that have been previously studied include the 1992 Little Skull Mountain Earthquake and groundwater subsidence in the Pahrump Valley (Lohman et al., 2002, and Utley, 2005). Several subsidence signals (2.5 -- 3.5 cm) present within Amargosa Valley represent aquifer response in close proximity to local groundwater withdrawal. Observed groundwater level declines in the vicinity of the subsidence bowls are also present. However, signals near Amargosa Flat and Ash Meadows National Wildlife Refuge appear to be a more complex regional aquifer response related either to distant groundwater use or other hydrologic processes related to the abundant spring activity in the area as groundwater levels have remained fairly steady in these regions. A subsidence signal at Frenchman Flat, within the Nevada Test Site, shows approximately 2 cm of subsidence with the majority occurring between 1998 and 2000. Groundwater use in this area was actually lower during this time period than during the previous six years covered by this study, and monitoring wells suggest a relatively constant depth to groundwater with no notable trend up or down. This suggests another mechanism behind the subsidence, including the possibility that three nuclear blast centers located within the subsidence bowl have altered groundwater recharge conditions in the area. The signal with the largest magnitude is related to mining activity at the Bullfrog Mine located west of Beatty, NV. At this location, as much as 8 cm of subsidence, occurring between 1995 and 2000, is centered on the eastern edge of the mine site and extends into the bedrock to the northeast. GPS data (Bennett et al, 2003 and Wernicke et al, 2004) suggest

  16. Plasmonic Enhancement of Raman Signal using Complex Metallic Nanostructures based on DNA Origami

    NASA Astrophysics Data System (ADS)

    Finkelstein, Gleb

    2015-03-01

    DNA-based nanostructures, such as ``DNA origami,'' have recently emerged as one of the leading techniques for precise positioning of nanoscale materials in fields ranging from computer science to biomedical engineering. The origami is composed of a single scaffold DNA strand to which smaller ``staple`` strands are attached through DNA complementarity. The staples help to fold the scaffold strand into the designed structure of a predetermined shape. The resulting templates are highly addressable and have proven to be versatile tools for site-specific placement of various nanocomponents, such as metallic nanoparticles, quantum dots, fluorophores, etc. Building upon massively paralleled assembly mechanism of the origami and its ability to position nanocomponents, one may hope to utilize it for biosensing purposes. One attractive goal is the Raman spectroscopy, which provides a highly specific chemical fingerprint. Unfortunately, the Raman scattering cross section is small; Surface Enhanced Raman Spectroscopy (SERS) enhances the otherwise weak Raman signal by trapping the analyte molecules in the regions of intense electric field produced near rough metallic surfaces. These ``hot spots`` can be understood as resulting from localized surface plasmon modes resonantly exited by the incident laser excitation. We have earlier shown that metallic nanoparticles controllably attached to DNA origami can be further enlarged via an in-solution metallization; this technique allowed us to build metallic structures of complex topology. Recently, we have performed Raman spectroscopy of molecules attached to these metallic assemblies. Specifically, DNA origami is first used to organize the metallic structures, followed by a covalent attachment of Raman-active molecules to the metal. We found that the substrates with four nanoparticles per origami produce a strongly enhanced Raman signal compared to the control samples with only one nanoparticle per origami for the same particle

  17. Glucose Starvation Alters Heat Shock Response, Leading to Death of Wild Type Cells and Survival of MAP Kinase Signaling Mutant.

    PubMed

    Plesofsky, Nora; Higgins, LeeAnn; Markowski, Todd; Brambl, Robert

    2016-01-01

    A moderate heat shock induces Neurospora crassa to synthesize large quantities of heat shock proteins that are protective against higher, otherwise lethal temperatures. However, wild type cells do not survive when carbohydrate deprivation is added to heat shock. In contrast, a mutant strain defective in a stress-activated protein kinase does survive the combined stresses. In order to understand the basis for this difference in survival, we have determined the relative levels of detected proteins in the mutant and wild type strain during dual stress, and we have identified gene transcripts in both strains whose quantities change in response to heat shock or dual stress. These data and supportive experimental evidence point to reasons for survival of the mutant strain. By using alternative respiratory mechanisms, these cells experience less of the oxidative stress that proves damaging to wild type cells. Of central importance, mutant cells recycle limited resources during dual stress by undergoing autophagy, a process that we find utilized by both wild type and mutant cells during heat shock. Evidence points to inappropriate activation of TORC1, the central metabolic regulator, in wild type cells during dual stress, based upon behavior of an additional signaling mutant and inhibitor studies.

  18. Glucose Starvation Alters Heat Shock Response, Leading to Death of Wild Type Cells and Survival of MAP Kinase Signaling Mutant

    PubMed Central

    Higgins, LeeAnn; Markowski, Todd; Brambl, Robert

    2016-01-01

    A moderate heat shock induces Neurospora crassa to synthesize large quantities of heat shock proteins that are protective against higher, otherwise lethal temperatures. However, wild type cells do not survive when carbohydrate deprivation is added to heat shock. In contrast, a mutant strain defective in a stress-activated protein kinase does survive the combined stresses. In order to understand the basis for this difference in survival, we have determined the relative levels of detected proteins in the mutant and wild type strain during dual stress, and we have identified gene transcripts in both strains whose quantities change in response to heat shock or dual stress. These data and supportive experimental evidence point to reasons for survival of the mutant strain. By using alternative respiratory mechanisms, these cells experience less of the oxidative stress that proves damaging to wild type cells. Of central importance, mutant cells recycle limited resources during dual stress by undergoing autophagy, a process that we find utilized by both wild type and mutant cells during heat shock. Evidence points to inappropriate activation of TORC1, the central metabolic regulator, in wild type cells during dual stress, based upon behavior of an additional signaling mutant and inhibitor studies. PMID:27870869

  19. The neuroprotective effects of α-iso-cubebene on dopaminergic cell death: involvement of CREB/Nrf2 signaling.

    PubMed

    Park, Sun Young; Son, Beung Gu; Park, Young Hoon; Kim, Cheol-Min; Park, Geuntae; Choi, Young-Whan

    2014-09-01

    As a part of ongoing studies to elucidate pharmacologically active components of Schisandra chinensis, we isolated and studied α-iso-cubebene. The neuroprotective mechanisms of α-iso-cubebene in human neuroblastoma SH-SY5Y cells were investigated. α-Iso-cubebene significantly inhibited cytotoxicity and apoptosis due to 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in dopaminergic SH-SY5Y cells. Pretreatment of cells with α-iso-cubebene reduced intracellular accumulation of ROS and calcium in response to 6-OHDA. The neuroprotective effects of α-iso-cubebene were found to result from protecting the mitochondrial membrane potential. Notably, α-iso-cubebene inhibited the release of apoptosis-inducing factor from the mitochondria into the cytosol and nucleus after 6-OHDA treatment. α-Iso-cubebene also induced the activation of PKA/PKB/CREB/Nrf2 and suppressed 6-OHDA-induced neurotoxicity. α-Iso-cubebene was found to induce phosphorylation of PKA and PKB and activate Nrf2 and CREB signaling pathways in a dose-dependent manner. Additionally, α-iso-cubebene stimulated the expression of the antioxidant response genes NQO1 and HO-1. Finally, α-iso-cubebene-mediated neuroprotective effects were found to be reversible after transfection with CREB and Nrf2 small interfering RNAs.

  20. From cell protection to death: may Ca2+ signals explain the chameleonic attributes of the mammalian prion protein?

    PubMed

    Sorgato, M Catia; Bertoli, Alessandro

    2009-02-06

    It is now accepted that a conformational change of the cellular prion protein (PrP(C)) generates the prion, the infectious agent responsible for lethal neurodegenerative disorders, named transmissible spongiform encephalopathies, or prion diseases. The mechanisms of prion-associated neurodegeneration are still obscure, as is the cell role of PrP(C), although increasing evidence attributes to PrP(C) important functions in cell survival. Such a behavioral dichotomy thus enables the prion protein to switch from a benign role under normal conditions, to the execution of neurons during disease. By reviewing data from models of prion disease and PrP(C)-null paradigms, which suggest a relation between the prion protein and Ca(2+) homeostasis, here we discuss the possibility that Ca(2+) is the factor behind the enigma of the pathophysiology of PrP(C). Ca(2+) features in almost all processes of cell signaling, and may thus tell us much about a protein that pivots between health and disease.

  1. Low-dose spiruchostatin-B, a potent histone deacetylase inhibitor enhances radiation-induced apoptosis in human lymphoma U937 cells via modulation of redox signaling.

    PubMed

    Rehman, Mati Ur; Jawaid, Paras; Zhao, Qing Li; Li, Peng; Narita, Koichi; Katoh, Tadashi; Shimizu, Tadamichi; Kondo, Takashi

    2016-06-01

    Spiruchostatin B (SP-B), is a potent histone deacetylase (HDAC) inhibitor, in addition to HDAC inhibition, the pharmacological effects of SP-B are also attributed to its ability to produce intracellular reactive oxygen species (ROS), particularly H2O2. In this study, we investigated the effects of low dose (non-toxic) SP-B on radiation-induced apoptosis in human lymphoma U937 cells in vitro. The treatment of cells with low-dose SP-B induced the acetylation of histones, however, does not induce apoptosis. Whereas, the combined treatment with SP-B and radiation significantly enhanced the radiation-induced apoptosis, suggesting the potential role of this combined treatment for future radiation therapy. Interestingly, the enhancement of apoptosis was accompanied by significant increased in the ROS generation. Pre-treatment with an antioxidant, N-acetyl-l-cysteine (NAC) significantly inhibited the enhancement of apoptosis induced by combined treatment, indicating that ROS play an essential role. It was also found that SP-B combined with radiation caused the activation of death receptor and intrinsic apoptotic pathways, via modulation of ROS-mediated signaling. Moreover, SP-B also significantly enhanced the radiation-induced apoptosis in other lymphoma cell lines such as Molt-4 and HL-60. Taken together, our findings suggest that the low-dose SP-B enhances radiation-induced apoptosis via modulation of redox signaling because of its ability to serve as an intracellular ROS generating agent, mainly (H2O2 or [Formula: see text]). This study provides further insights into the mechanism of action of SP-B with radiation and demonstrates that SP-B can be used as a future novel sensitizer for radiation therapy.

  2. Disruption of IP₃R2-mediated Ca²⁺ signaling pathway in astrocytes ameliorates neuronal death and brain damage while reducing behavioral deficits after focal ischemic stroke.

    PubMed

    Li, Hailong; Xie, Yicheng; Zhang, Nannan; Yu, Yang; Zhang, Qiao; Ding, Shinghua

    2015-12-01

    Inositol trisphosphate receptor (IP3R)-mediated intracellular Ca(2+) increase is the major Ca(2+) signaling pathway in astrocytes in the central nervous system (CNS). Ca(2+) increases in astrocytes have been found to modulate neuronal function through gliotransmitter release. We previously demonstrated that astrocytes exhibit enhanced Ca(2+) signaling in vivo after photothrombosis (PT)-induced ischemia, which is largely due to the activation of G-protein coupled receptors (GPCRs). The aim of this study is to investigate the role of astrocytic IP3R-mediated Ca(2+) signaling in neuronal death, brain damage and behavior outcomes after PT. For this purpose, we conducted experiments using homozygous type 2 IP3R (IP3R2) knockout (KO) mice. Histological and immunostaining studies showed that IP3R2 KO mice were indeed deficient in IP3R2 in astrocytes and exhibited normal brain cytoarchitecture. IP3R2 KO mice also had the same densities of S100β+ astrocytes and NeuN+ neurons in the cortices, and exhibited the same glial fibrillary acidic protein (GFAP) and glial glutamate transporter (GLT-1) levels in the cortices and hippocampi as compared with wild type (WT) mice. Two-photon (2-P) imaging showed that IP3R2 KO mice did not exhibit ATP-induced Ca(2+) waves in vivo in the astrocytic network, which verified the disruption of IP3R-mediated Ca(2+) signaling in astrocytes of these mice. When subject to PT, IP3R2 KO mice had smaller infarction than WT mice in acute and chronic phases of ischemia. IP3R2 KO mice also exhibited less neuronal apoptosis, reactive astrogliosis, and tissue loss than WT mice. Behavioral tests, including cylinder, hanging wire, pole and adhesive tests, showed that IP3R2 KO mice exhibited reduced functional deficits after PT. Collectively, our study demonstrates that disruption of astrocytic Ca(2+) signaling by deleting IP3R2s has beneficial effects on neuronal and brain protection and functional deficits after stroke. These findings reveal a novel non

  3. Enhanced expression of ADCY1 underlies aberrant neuronal signalling and behaviour in a syndromic autism model

    PubMed Central

    Sethna, Ferzin; Feng, Wei; Ding, Qi; Robison, Alfred J.; Feng, Yue; Wang, Hongbing

    2017-01-01

    Fragile X syndrome (FXS), caused by the loss of functional FMRP, is a leading cause of autism. Neurons lacking FMRP show aberrant mRNA translation and intracellular signalling. Here, we identify that, in Fmr1 knockout neurons, type 1 adenylyl cyclase (Adcy1) mRNA translation is enhanced, leading to excessive production of ADCY1 protein and insensitivity to neuronal stimulation. Genetic reduction of Adcy1 normalizes the aberrant ERK1/2- and PI3K-mediated signalling, attenuates excessive protein synthesis and corrects dendritic spine abnormality in Fmr1 knockout mice. Genetic reduction of Adcy1 also ameliorates autism-related symptoms including repetitive behaviour, defective social interaction and audiogenic seizures. Moreover, peripheral administration of NB001, an experimental compound that preferentially suppresses ADCY1 activity over other ADCY subtypes, attenuates the behavioural abnormalities in Fmr1 knockout mice. These results demonstrate a connection between the elevated Adcy1 translation and abnormal ERK1/2 signalling and behavioural symptoms in FXS. PMID:28218269

  4. Enhanced electrokinetic manipulation and impedance sensing using FPGA digital signal processing

    NASA Astrophysics Data System (ADS)

    Higginbotham, Steven N.; Sweatman, Denis R.

    2006-01-01

    Electrokinetic manipulation of microscopic biological particles, such as bacteria and other cells, is useful in the technology of lab-on-a-chip devices and micro-total-analysis systems (μTAS). In electrokinetic manipulation, non-uniform electric fields are used to exploit the dielectric properties of suspended biological microparticles, to induce forces and torques on the particles. The electric fields are produced by planar electrode arrays patterned on electrically-insulating substrates. Biological microparticles are dielectrically-heterogeneous structures. Each different type of biological cell has a distinct dielectric frequency response signature. This dielectric distinction allows specificity when manipulating biological microparticles using electrokinetics. Electrokinetic microbiological particle manipulation has numerous potential applications in biotechnology, such as the separation and study of cancerous cells, determining the viability of cells, as well as enabling more automation and parallelization in microbiological research and pathology. This paper presents microfabricated devices for the manipulation of biological microparticles using electrokinetics. Methods of impedance sensing for determining microparticle concentration and type are also discussed. This paper also presents methods of using digital signal processing systems to enhance the manipulation and sensing of the microbiological particles. A Field-Programmable Gate Array (FPGA) based system is demonstrated which is used to digitally synthesize signals for electrokinetic actuation, and to process signals for impedance sensing.

  5. Enhanced Refocusing of Fat Signals using Optimized Multi-pulse Echo Sequences

    PubMed Central

    Stokes, Ashley M.; Feng, Yesu; Mitropoulos, Tanya; Warren, Warren S.

    2012-01-01

    Endogenous magnetic resonance contrast based on the localized composition of fat in vivo can provide functional information. We found that the unequal pulse timings of the Uhrig’s Dynamical Decoupling (UDD) multipulse echo sequences significantly alter the signal intensity compared to conventional, equal-spaced Carr-Purcell-Meiboom-Gill (CPMG) sequences. The signal increases and decreases depending on the tissue and sequence parameters, as well as on the interpulse spacings; particularly strong differences were observed in fatty tissues, which have a highly structured morphology and a wide range of chemical shifts and J-couplings. We found that the predominant mechanism for fat refocusing under multipulse echo sequences is the chemical structure, with stimulated echoes playing a pivotal role. As a result, specialized pulse sequences can be designed to optimize refocusing of the fat chemical shifts and J-couplings, where the degree of refocusing can be tailored to specific types of fats. To determine the optimal time delays, we simulated various UDD and CPMG pulse sequence timings, and these results are compared to experimental results obtained on excised and in vivo fatty tissue. Applications to intermolecular multiple-quantum coherence (iMQC) imaging, where the improved echo refocusing translates directly into signal enhancements, are presented as well. PMID:22627966

  6. Induction of a quorum sensing pathway by environmental signals enhances group A streptococcal resistance to lysozyme

    PubMed Central

    Chang, Jennifer C.; Jimenez, Juan Cristobal; Federle, Michael J.

    2015-01-01

    Summary The human-restricted pathogen Streptococcus pyogenes (Group A Streptococcus, GAS) is responsible for wide-ranging pathologies at numerous sites in the body, but has the proclivity to proliferate in individuals asymptomatically. The ability to survive in diverse tissues is undoubtedly benefited by sensory pathways that recognize environmental cues corresponding to stress and nutrient availability and thereby trigger adaptive responses. We investigated the impact that environmental signals contribute to cell-to-cell chemical communication (quorum sensing, QS) by monitoring activity of the Rgg2/Rgg3 and SHP-pheromone system in GAS. We identified metal limitation and the alternate carbon source mannose as two environmental indicators likely to be encountered by GAS in the host that significantly induced the Rgg-SHP system. Disruption of the metal regulator MtsR partially accounted for the response to metal depletion, whereas ptsABCD was primarily responsible for QS induction due to mannose, but each sensory system induced Rgg-SHP signaling apparently by different mechanisms. Significantly, we found that induction of QS, regardless of the GAS serotype tested, led to enhanced resistance to the antimicrobial agent lysozyme. These results indicate the benefits for GAS to integrate environmental signals with intercellular communication pathways in protection from host defenses. PMID:26062094

  7. Enhancing dopaminergic signaling and histone acetylation promotes long-term rescue of deficient fear extinction

    PubMed Central

    Whittle, N; Maurer, V; Murphy, C; Rainer, J; Bindreither, D; Hauschild, M; Scharinger, A; Oberhauser, M; Keil, T; Brehm, C; Valovka, T; Striessnig, J; Singewald, N

    2016-01-01

    Extinction-based exposure therapy is used to treat anxiety- and trauma-related disorders; however, there is the need to improve its limited efficacy in individuals with impaired fear extinction learning and to promote greater protection against return-of-fear phenomena. Here, using 129S1/SvImJ mice, which display impaired fear extinction acquisition and extinction consolidation, we revealed that persistent and context-independent rescue of deficient fear extinction in these mice was associated with enhanced expression of dopamine-related genes, such as dopamine D1 (Drd1a) and -D2 (Drd2) receptor genes in the medial prefrontal cortex (mPFC) and amygdala, but not hippocampus. Moreover, enhanced histone acetylation was observed in the promoter of the extinction-regulated Drd2 gene in the mPFC, revealing a potential gene-regulatory mechanism. Although enhancing histone acetylation, via administering the histone deacetylase (HDAC) inhibitor MS-275, does not induce fear reduction during extinction training, it promoted enduring and context-independent rescue of deficient fear extinction consolidation/retrieval once extinction learning was initiated as shown following a mild conditioning protocol. This was associated with enhanced histone acetylation in neurons of the mPFC and amygdala. Finally, as a proof-of-principle, mimicking enhanced dopaminergic signaling by L-dopa treatment rescued deficient fear extinction and co-administration of MS-275 rendered this effect enduring and context-independent. In summary, current data reveal that combining dopaminergic and epigenetic mechanisms is a promising strategy to improve exposure-based behavior therapy in extinction-impaired individuals by initiating the formation of an enduring and context-independent fear-inhibitory memory. PMID:27922638

  8. Quantification of High-Molecular Weight Protein Platforms by AQUA Mass Spectrometry as Exemplified for the CD95 Death-Inducing Signaling Complex (DISC).

    PubMed

    Warnken, Uwe; Schleich, Kolja; Schnölzer, Martina; Lavrik, Inna

    2013-06-27

    Contemporary quantitative mass spectrometry provides fascinating opportunities in defining the stoichiometry of high-molecular weight complexes or multiprotein platforms. The composition stoichiometry of multiprotein platforms is a key to understand the regulation of complex signaling pathways and provides a basis for constructing models in systems biology. Here we present an improved AQUA technique workflow that we adapted for the quantitative mass spectrometry analysis of the stoichiometry of the CD95 (Fas/APO-1) death inducing signaling complex (DISC). The DISC is a high-molecular weight platform essential for the initiation of CD95-mediated apoptotic and non-apoptotic responses. For protein quantification, CD95 DISCs were immunoprecipitated and proteins in the immunoprecipitations were separated by one-dimensional gel electrophoresis, followed by protein quantification using the AQUA technique. We will discuss in detail AQUA analysis of the CD95 DISC focusing on the key issues of this methodology, i.e., selection and validation of AQUA peptides. The application of this powerful method allowed getting new insights into mechanisms of procaspase-8 activation at the DISC and apoptosis initiation [1]. Here we discuss the AQUA methodology adapted by us for the analysis of the CD95 DISC in more detail. This approach paves the way for the successful quantification of multiprotein complexes and thereby delineating the intrinsic details of molecular interactions.

  9. TLR9-ERK-mTOR signaling is critical for autophagic cell death induced by CpG oligodeoxynucleotide 107 combined with irradiation in glioma cells.

    PubMed

    Li, Xiaoli; Cen, Yanyan; Cai, Yongqing; Liu, Tao; Liu, Huan; Cao, Guanqun; Liu, Dan; Li, Bin; Peng, Wei; Zou, Jintao; Pang, Xueli; Zheng, Jiang; Zhou, Hong

    2016-06-02

    Synthetic oligodeoxynucleotides containing unmethylated CpG dinucleotides (CpG ODN) function as potential radiosensitizers for glioma treatment, although the underlying mechanism is unclear. It was observed that CpG ODN107, when combined with irradiation, did not induce apoptosis. Herein, the effect of CpG ODN107 + irradiation on autophagy and the related signaling pathways was investigated. In vitro, CpG ODN107 + irradiation induced autophagosome formation, increased the ratio of LC3 II/LC3 I, beclin 1 and decreased p62 expression in U87 cells. Meanwhile, CpG ODN107 also increased LC3 II/LC3 I expression in U251 and CHG-5 cells. In vivo, CpG ODN107 combined with local radiotherapy induced autophagosome formation in orthotopic transplantation tumor. Investigation of the molecular mechanisms demonstrated that CpG ODN107 + irradiation increased the levels of TLR9 and p-ERK, and decreased the level of p-mTOR in glioma cells. Further, TLR9-specific siRNA could affect the expressions of p-ERK and autophagy-related proteins in glioma cells. Taken together, CpG ODN107 combined with irradiation could induce autophagic cell death, and this effect was closely related to the TLR9-ERK-mTOR signaling pathway in glioma cells, providing new insights into the investigation mechanism of CpG ODN.

  10. Nav1.4 deregulation in dystrophic skeletal muscle leads to Na+ overload and enhanced cell death.

    PubMed

    Hirn, Carole; Shapovalov, George; Petermann, Olivier; Roulet, Emmanuelle; Ruegg, Urs T

    2008-08-01

    Duchenne muscular dystrophy (DMD) is a hereditary degenerative disease manifested by the absence of dystrophin, a structural, cytoskeletal protein, leading to muscle degeneration and early death through respiratory and cardiac muscle failure. Whereas the rise of cytosolic Ca(2+) concentrations in muscles of mdx mouse, an animal model of DMD, has been extensively documented, little is known about the mechanisms causing alterations in Na(+) concentrations. Here we show that the skeletal muscle isoform of the voltage-gated sodium channel, Na(v)1.4, which represents over 90% of voltage-gated sodium channels in muscle, plays an important role in development of abnormally high Na(+) concentrations found in muscle from mdx mice. The absence of dystrophin modifies the expression level and gating properties of Na(v)1.4, leading to an increased Na(+) concentration under the sarcolemma. Moreover, the distribution of Na(v)1.4 is altered in mdx muscle while maintaining the colocalization with one of the dystrophin-associated proteins, syntrophin alpha-1, thus suggesting that syntrophin is an important linker between dystrophin and Na(v)1.4. Additionally, we show that these modifications of Na(v)1.4 gating properties and increased Na(+) concentrations are strongly correlated with increased cell death in mdx fibers and that both cell death and Na(+) overload can be reversed by 3 nM tetrodotoxin, a specific Na(v)1.4 blocker.

  11. SH2B1beta adaptor is a key enhancer of RET tyrosine kinase signaling.

    PubMed

    Donatello, S; Fiorino, A; Degl'Innocenti, D; Alberti, L; Miranda, C; Gorla, L; Bongarzone, I; Rizzetti, M G; Pierotti, M A; Borrello, M G

    2007-10-04

    The RET gene encodes two main isoforms of a receptor tyrosine kinase (RTK) implicated in various human diseases. Activating germ-line point mutations are responsible for multiple endocrine neoplasia type 2-associated medullary thyroid carcinomas, inactivating germ-line mutations for Hirschsprung's disease, while somatic rearrangements (RET/PTCs) are specific to papillary thyroid carcinomas. SH2B1beta, a member of the SH2B adaptors family, and binding partner for several RTKs, has been recently described to interact with proto-RET. Here, we show that both RET isoforms and its oncogenic derivatives bind to SH2B1beta through the SRC homology 2 (SH2) domain and a kinase activity-dependent mechanism. As a result, RET phosphorylates SH2B1beta, which in turn enhances its autophosphorylation, kinase activity, and downstream signaling. RET tyrosine residues 905 and 981 are important determinants for functional binding of the adaptor, as removal of both autophosphorylation sites displaces its recruitment. Binding of SH2B1beta appears to protect RET from dephosphorylation by protein tyrosine phosphatases, and might represent a likely mechanism contributing to its upregulation. Thus, overexpression of SH2B1beta, by enhancing phosphorylation/activation of RET transducers, potentiates the cellular differentiation and the neoplastic transformation thereby induced, and counteracts the action of RET inhibitors. Overall, our results identify SH2B1beta as a key enhancer of RET physiologic and pathologic activities.

  12. Berberine inhibits EGFR signaling and enhances the antitumor effects of EGFR inhibitors in gastric cancer

    PubMed Central

    Wang, Junxiong; Yang, Shuo; Cai, Xiqiang; Dong, Jiaqiang; Chen, Zhangqian; Wang, Rui; Zhang, Song; Cao, Haichao; Lu, Di; Jin, Tong; Nie, Yongzhan; Hao, Jianyu; Fan, Daiming

    2016-01-01

    Cetuximab plus chemotherapy for advanced gastric cancer (GC) shows an active result in phase 2 trials. Unfortunately, Combination of cetuximab does not provide enough benefit to chemotherapy alone in phase 3 trials. Studies have demonstrated that berberine can suppress the activation of EGFR in tumors. In this study, we evaluated whether berberine could enhance the effects of EGFR-TKIs in GC cell lines and xenograft models. Our data suggest that berberine could effectively enhance the activity of erlotinib and cetuximab in vitro and in vivo. Berberine was found to inhibit growth in GC cell lines and to induce apoptosis. These effects were linked to inhibition of EGFR signaling activation, including the phosphorylation of STAT3. The expressions of Bcl-xL and Cyclind1 proteins were decreased, whereas the levels of cleavage of poly-ADP ribose polymerase (PARP) were considerably increased in the cell lines in response to berberine treatment. These results suggest a potential role for berberine in the treatment of GC, particularly in combination with EGFR-TKIs therapy. Berberine may be a competent therapeutic agent in GC where it can enhance the effects of EGFR inhibitors. PMID:27738318

  13. Pharmacology of novel small-molecule tubulin inhibitors in glioblastoma cells with enhanced EGFR signalling.

    PubMed

    Phoa, Athena F; Browne, Stephen; Gurgis, Fadi M S; Åkerfeldt, Mia C; Döbber, Alexander; Renn, Christian; Peifer, Christian; Stringer, Brett W; Day, Bryan W; Wong, Chin; Chircop, Megan; Johns, Terrance G; Kassiou, Michael; Munoz, Lenka

    2015-12-15

    We recently reported that CMPD1, originally developed as an inhibitor of MK2 activation, primarily inhibits tubulin polymerisation and induces apoptosis in glioblastoma cells. In the present study we provide detailed pharmacological investigation of CMPD1 analogues with improved molecular properties. We determined their anti-cancer efficacy in glioblastoma cells with enhanced EGFR signalling, as deregulated EGFR often leads to chemoresistance. Eight analogues of CMPD1 with varying lipophilicity and basicity were synthesised and tested for efficacy in the cell viability assay using established glioblastoma cell lines and patient-derived primary glioblastoma cells. The mechanism of action for the most potent analogue 15 was determined using MK2 activation and tubulin polymerisation assays, together with the immunofluorescence analysis of the mitotic spindle formation. Apoptosis was analysed by Annexin V staining, immunoblotting analysis of bcl-2 proteins and PARP cleavage. The apoptotic activity of CMPD1 and analogue 15 was comparable across glioblastoma cell lines regardless of the EGFR status. Primary glioblastoma cells of the classical subtype that are characterized by enhanced EGFR activity were most sensitive to the treatment with CMPD1 and 15. In summary, we present mechanism of action for a novel small molecule tubulin inhibitor, compound 15 that inhibits tubulin polymerisation and mitotic spindle formation, induces degradation of anti-apoptotic bcl-2 proteins and leads to apoptosis of glioblastoma cells. We also demonstrate that the enhanced EGFR activity does not decrease the efficacy of tubulin inhibitors developed in this study.

  14. Enhancement of early cardiac differentiation of dedifferentiated fat cells by dimethyloxalylglycine via notch signaling pathway

    PubMed Central

    Li, Fuhai; Li, Zongzhuang; Jiang, Zhi; Tian, Ye; Wang, Zhi; Yi, Wei; Zhang, Chenyun

    2016-01-01

    Background: Hypoxia has been reported to possess the ability to induce mature lipid-filled adipocytes to differentiate into fibroblast-like multipotent dedifferentiated fat (DFAT) cells and stem cells such as iPSCs (interstitial pluripotent stem cells) and ESCs (embryonic stem cells) and then to differentiate into cardiomyocytes. However, the effect of hypoxia on cardiac differentiation of DFAT cells and its underlying molecular mechanism remains to be investigated. Objective: To investigate the role of hypoxia in early cardiac differentiation of DFAT cells and the underlying molecular mechanism. Methods: DFAT cells were prepared from 4 to 6 week-age mice and cultured under hypoxic conditions by adding Prolyl hydroxylase inhibitor and dimethyloxalylglycine (DMOG) into the culture media. To inhibit or block Notch signaling, γ-secretase inhibitor-II (GSI-II) and Notch1 siRNA (si-Notch1) were used. DFAT cell viability was detected using MTT assay. qRT-PCR, immunofluorescence microscopy and western blotting were used to evaluate the cardiac differentiation of DFAT cells and co-immunoprecipitation was used to study the interaction between HIF-1α and Notch signaling. Results: 0.6-mM DMOG failed to affect the viability of DFAT cells, but stimulated the cells to express early cardiac transcription factors including Islet1, Nkx2.5 and Gata4 in a time-dependent manner and increase the number of cTnT+ cardiomyocytes (detected at the 28th day after stimulation). It was also demonstrated that DMOG was involved in HIF-1α and Notch signaling as well as HIF-1α-NICD complex formation. Conclusion: Hypoxia enhanced early cardiac differentiation of DFAT cells through HIF-1α and Notch signaling pathway. PMID:27904680

  15. Enhancement of early cardiac differentiation of dedifferentiated fat cells by dimethyloxalylglycine via notch signaling pathway.

    PubMed

    Li, Fuhai; Li, Zongzhuang; Jiang, Zhi; Tian, Ye; Wang, Zhi; Yi, Wei; Zhang, Chenyun

    2016-01-01

    Background: Hypoxia has been reported to possess the ability to induce mature lipid-filled adipocytes to differentiate into fibroblast-like multipotent dedifferentiated fat (DFAT) cells and stem cells such as iPSCs (interstitial pluripotent stem cells) and ESCs (embryonic stem cells) and then to differentiate into cardiomyocytes. However, the effect of hypoxia on cardiac differentiation of DFAT cells and its underlying molecular mechanism remains to be investigated. Objective: To investigate the role of hypoxia in early cardiac differentiation of DFAT cells and the underlying molecular mechanism. Methods: DFAT cells were prepared from 4 to 6 week-age mice and cultured under hypoxic conditions by adding Prolyl hydroxylase inhibitor and dimethyloxalylglycine (DMOG) into the culture media. To inhibit or block Notch signaling, γ-secretase inhibitor-II (GSI-II) and Notch1 siRNA (si-Notch1) were used. DFAT cell viability was detected using MTT assay. qRT-PCR, immunofluorescence microscopy and western blotting were used to evaluate the cardiac differentiation of DFAT cells and co-immunoprecipitation was used to study the interaction between HIF-1α and Notch signaling. Results: 0.6-mM DMOG failed to affect the viability of DFAT cells, but stimulated the cells to express early cardiac transcription factors including Islet1, Nkx2.5 and Gata4 in a time-dependent manner and increase the number of cTnT(+) cardiomyocytes (detected at the 28(th) day after stimulation). It was also demonstrated that DMOG was involved in HIF-1α and Notch signaling as well as HIF-1α-NICD complex formation. Conclusion: Hypoxia enhanced early cardiac differentiation of DFAT cells through HIF-1α and Notch signaling pathway.

  16. Honokiol enhances adipocyte differentiation by potentiating insulin signaling in 3T3-L1 preadipocytes.

    PubMed

    Choi, Sun-Sil; Cha, Byung-Yoon; Iida, Kagami; Sato, Masako; Lee, Young-Sil; Teruya, Toshiaki; Yonezawa, Takayuki; Nagai, Kazuo; Woo, Je-Tae

    2011-07-01

    Adipose tissue plays an essential role in energy homeostasis as a metabolic and endocrine organ. Accordingly, adipocytes are emerging as a major drug target for obesity and obesity-mediated metabolic syndrome. Dysfunction of enlarged adipocytes in obesity is involved in obesity-mediated metabolic syndrome. Adipocytokines, such as adiponectin released from small adipocytes, are able to prevent these disorders. In this study, we found that honokiol, an ingredient of Magnolia officinalis used in traditional Chinese and Japanese medicines, enhanced adipocyte differentiation in 3T3-L1 preadipocytes. Oil Red O staining showed that treatment with honokiol in the presence of insulin dose-dependently increased lipid accumulation in 3T3-L1 preadipoyctes although its activity was weak compared with rosiglitazone. During adipocyte differentiation, the expression of peroxisome proliferator-activated receptor γ2 (PPARγ2) mRNA and PPARγ target genes such as adipocyte protein 2 (aP2), adiponectin, and GLUT4 was induced by treatment with 10 μM honokiol. However, honokiol failed to show direct binding to the PPARγ ligand-binding domain in vitro. In preadipocytes, treatment with honokiol in the presence of insulin increased the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 protein and Akt protein, early insulin signaling pathways related to adipocyte differentiation, compared with insulin-only treatment. Taken together, our results suggest that honokiol promotes adipocyte differentiation through increased expression of PPARγ2 mRNA and potentiation of insulin signaling pathways such as the Ras/ERK1/2 and phosphoinositide-3-kinase (PI3K)/Akt signaling pathways.

  17. Enhanced autophagy signaling in diabetic rats with ischemia-induced seizures.

    PubMed

    Xia, Luoxing; Lei, Zhigang; Shi, Zhongshan; Guo, Dave; Su, Henry; Ruan, Yiwen; Xu, Zao C

    2016-07-15

    Seizures are among the most common neurological sequelae of stroke, and ischemic insult in diabetes notably increases the incidence of seizures. Recent studies indicated that autophagy influences the outcome of stroke and involved in epileptogenesis. However, the association of autophagy and post-ischemic seizures in diabetes remains unclear. The present study aimed to reveal the involvement of autophagy in the seizures following cerebral ischemia in diabetes. Diabetes was induced in adult male Wistar rats by intraperitoneal injection of streptozotocin (STZ). The diabetic rats were subjected to transient forebrain ischemia. The neuronal damage was assessed using hematoxylin-eosin staining. Western blotting and immunohistochemistry were performed to investigate the alteration of autophagy marker microtubule-associated protein light chain 1B (LC3B). The results showed that all diabetic animals developed seizures after ischemia. However, no apparent cell death was observed in the hippocampus of seizure rats 12h after the insult. The expression of LC3B was significantly enhanced in naïve animals after ischemia and was further increased in diabetic animals after ischemia. Immunofluorescence double-labeling study indicated that LC3B was mainly increased in neurons. Our study demonstrated, for the first time, that autophagy activity is significantly increased in diabetic animals with ischemia-induced seizures. Further studies are needed to explore the role of autophagy in seizure generation after ischemia in diabetic conditions.

  18. Induction of mitochondrial alternative oxidase in response to a cell signal pathway down-regulating the cytochrome pathway prevents programmed cell death.

    PubMed

    Vanlerberghe, Greg C; Robson, Christine A; Yip, Justine Y H

    2002-08-01

    Treatment of tobacco (Nicotiana tabacum L. cv Petit Havana SR1) cells with cysteine (Cys) triggers a signal pathway culminating in a large loss of mitochondrial cytochrome (cyt) pathway capacity. This down-regulation of the cyt path likely requires events outside the mitochondrion and is effectively blocked by cantharidin or endothall, indicating that protein dephosphorylation is one critical process involved. Generation of reactive oxygen species, cytosolic protein synthesis, and Ca(2+) flux from organelles also appear to be involved. Accompanying the loss of cyt path is a large induction of alternative oxidase (AOX) protein and capacity. Induction of AOX allows the cells to maintain high rates of respiration, indicating that the lesion triggered by Cys is in the cyt path downstream of ubiquinone. Consistent with this, transgenic (AS8) cells unable to induce AOX (due to the presence of an antisense transgene) lose all respiratory capacity upon Cys treatment. This initiates in AS8 a programmed cell death pathway, as evidenced by the accumulation of oligonucleosomal fragments of DNA as the culture dies. Alternatively, wild-type cells remain viable and eventually recover their cyt path. Induction of AOX in response to a chemical inhibition of the cyt path (by antimycin A) is also dependent upon protein dephosphorylation and the generation of reactive oxygen species. Common events required for both down-regulation of the cyt path and induction of AOX may represent a mechanism to coordinate the biogenesis of these two electron transport paths. Such coordinate regulation may be necessary, not only to satisfy metabolic demands, but also to modulate the initiation of a programmed cell death pathway responsive to mitochondrial respiratory status.

  19. PICT-1 triggers a pro-death autophagy through inhibiting rRNA transcription and AKT/mTOR/p70S6K signaling pathway

    PubMed Central

    Hu, Bo; Wang, Zhiwei; Zhang, Fang; Tsai, Hsiangi; Zhang, Jianping; Zhou, Lanzhen; Wang, Lijun; Wang, Xinyu; Huang, Laiqiang

    2016-01-01

    PICT-1 was originally identified as a tumor suppressor. Here, we found that PICT-1 overexpression triggered pro-death autophagy without nucleolar disruption or p53 accumulation in U251 and MCF7 cells. Truncated PICT-1 fragments 181-346 and 1-346, which partly or totally lack nucleolar localization, showed weaker autophagy-inducing effects than full-length PICT-1 and a well-defined nucleolar mutant (181-479). Furthermore, PICT-1 partly localizes to the nucleolar fibrillar center (FC) and directly binds to ribosomal DNA (rDNA) gene loci, where it interacts with upstream binding factor (UBF). Overexpression of PICT-1 or the 181-479 mutant, but not the 1-346 or 181-346 mutants, markedly inhibited the phosphorylation of UBF and the recruitment of rRNA polymerase I (Pol I) to the rDNA promoter in response to serum stimulation, thereby suppressing rRNA transcription, suggesting that rRNA transcription inhibition might be an important contributor to PICT-1-induced autophagy. This is supported by the finding that CX-5461, a specific Pol I inhibitor, also induced autophagy. In addition, both CX-5461 and PICT-1, but not the 1-346 or 181-346 mutants, significantly suppressed the activation of the Akt/mTOR/p70S6K signaling pathway. Our data show that PICT-1 triggers pro-death autophagy through inhibition of rRNA transcription and the inactivation of AKT/mTOR/p70S6K pathway, independent of nucleolar disruption and p53 activation. PMID:27729611

  20. Cannabidiol protects against hepatic ischemia/reperfusion injury by attenuating inflammatory signaling and response, oxidative/nitrative stress, and cell death

    PubMed Central

    Mukhopadhyay, Partha; Rajesh, Mohanraj; Horváth, Béla; Bátkai, Sándor; Park, Ogyi; Tanashian, Galin; Gao, Rachel Y; Patel, Vivek; Wink, David A.; Liaudet, Lucas; Haskó, György; Mechoulam, Raphael; Pacher, Pál

    2011-01-01

    Ischemia-reperfusion (I/R) is a pivotal mechanism of liver damage following liver transplantation or hepatic surgery. We have investigated the effects of cannabidiol(CBD), the non-psychotropic constituent of marijuana, in a mouse model of hepatic I/R injury. I/R triggered time-dependent increases/changes in markers of liver injury (serum transaminases), hepatic oxidative/nitrative stress (4-hydroxy-2-nonenal, nitrotyrosine content/staining, gp91phox and inducible nitric oxide synthase mRNA), mitochondrial dysfunction (decreased complex I activity), inflammation (tumor necrosis factor alpha (TNF-α), cyclooxygenase 2, macrophage inflammatory protein-1α/2, inter-cellular adhesion molecule 1 mRNA levels, tissue neutrophil infiltration, nuclear factor kappa B (NF-KB) activation), stress signaling (p38MAPK and JNK) and cell death (DNA fragmentation, PARP activity, and TUNEL). CBD significantly reduced the extent of liver inflammation, oxidative/nitrative stress and cell death, and also attenuated the bacterial endotoxin-triggered NF-KB activation and TNF-α production in isolated Kupffer cells, likewise the adhesion molecules expression in primary human liver sinusoidal endothelial cells stimulated with TNF-α, and attachment of human neutrophils to the activated endothelium. These protective effects were preserved in CB2 knockout mice and were not prevented by CB1/2 antagonists in vitro. Thus, CBD may represent a novel, protective strategy against I/R injury by attenuating key inflammatory pathways and oxidative/nitrative tissue injury, independent from classical CB1/2 receptors. PMID:21362471

  1. Voodoo death.

    PubMed

    Lester, David

    2009-01-01

    Scholarly writing on voodoo death is reviewed. Criticisms that voodoo deaths in indigenous societies have never been well documented are refuted with cases medically documented in developed nations. The work of Cannon and Richter on sudden death in animals is reviewed and dismissed as irrelevant for understanding voodoo death. The role of starvation and dehydration is discussed, and it is suggested that the given-up/giving-up hypothesis best fits the phenomenon of voodoo death. Hypotheses for future research are suggested.

  2. Enhanced BDNF signalling following chronic hypoxia potentiates catecholamine release from cultured rat adrenal chromaffin cells

    PubMed Central

    Scott, Angela L; Zhang, Min; Nurse, Colin A

    2015-01-01

    Environmental stressors, including chronic hypoxia, enhance the ability of adrenomedullary chromaffin cells (AMCs) to secrete catecholamines; however, the underlying molecular mechanisms remain unclear. Here, we investigated the role of brain-derived neurotrophic factor (BDNF) signalling in rat AMCs exposed to chronic hypoxia. In rat adrenal glands, BDNF and its tropomyosin-related kinase B (TrkB) receptor are highly expressed in the cortex and medulla, respectively. Exposure of AMCs to chronic hypoxia (2% O2; 48 h) in vitro caused a significant increase to TrkB mRNA expression. A similar increase was observed in an immortalized chromaffin cell line (MAH cells); however, it was absent in MAH cells deficient in the transcription factor HIF-2α. A specific TrkB agonist, 7,8-dihydroxyflavone (7,8-DHF), stimulated quantal catecholamine secretion from chronically hypoxic (CHox; 2% O2) AMCs to a greater extent than normoxic (Nox; 21% O2) controls. Activation of TrkB by BDNF or 7,8-DHF increased intracellular Ca2+ ([Ca2+]i), an effect that was significantly larger in CHox cells. The 7,8-DHF-induced [Ca2+]i rise was sensitive to the tyrosine kinase inhibitor K252a and nickel (2 mm), but not the Ca2+ store-depleting agent cyclopiazonic acid. Blockade of T-type calcium channels with TTA-P2 (1 μm) or voltage-gated Na+ channels with TTX inhibited BDNF-induced [Ca2+]i increases. BDNF also induced a dose-dependent enhancement of action potential firing in CHox cells. These data demonstrate that during chronic hypoxia, enhancement of BDNF-TrkB signalling increases voltage-dependent Ca2+ influx and catecholamine secretion in chromaffin cells, and that T-type Ca2+ channels play a key role in the signalling pathway. Key points We investigated the role of the neurotrophin BDNF signalling via the TrkB receptor in rat adrenomedullary chromaffin cells (AMCs) exposed to normoxia (Nox; 21% O2) and chronic hypoxia (CHox; 2% O2) in vitro for ∼48 h. TrkB receptor expression was

  3. Peroxidase-encapsulated cyclodextrin nanosponge immunoconjugates as a signal enhancement tool in optical and electrochemical assays.

    PubMed

    Wajs, Ewelina; Caldera, Fabrizio; Trotta, Francesco; Fragoso, Alex

    2014-01-21

    Cyclodextrin nanosponges bearing carboxylate groups have been prepared by crosslinking β-cyclodextrin with pyromellitic dianhydride to form a carboxylic acid terminated nanoporous material. The surface of the particles was covalently modified with an anti-IgG antibody and then loaded with horseradish peroxidase. The structures of unmodified and protein modified nanosponge particles were investigated by Raman spectroscopy and imaging methods. Confocal microscopy indicates that the antibody is located in the outside of the particle while HRP is encapsulated in the inner part. The possibility to use these modified nanosponges as a signal enhancement tool in enzyme-linked colorimetric and electrochemical assays was evaluated using a sandwich format comprising immobilised gliadin as an antigen, a target anti-gliadin antibody and an anti-IgG antibody conjugated to the enzyme-loaded nanosponge immunoconjugates.

  4. Numb/Notch signaling pathway modulation enhances human pancreatic cancer cell radiosensitivity.

    PubMed

    Bi, Yi-Liang; Min, Min; Shen, Wei; Liu, Yan

    2016-11-01

    The present study aims to evaluate whether repression of the Numb/Notch signaling pathway affects the radiosensitivity of human pancreatic cancer cell lines. Different doses of X-rays (0, 2, 3, 4, and 5 Gy) were applied to the PANC-1, SW1990, and MIA PaCa-2 human pancreatic cancer cell lines, and the Numb/Notch pathway inhibitor DAPT was added at different doses (0, 1, 3, and 5 μmol/l). MTT assay, colony formation assay, flow cytometry, scratch assay, and Transwell experiments were performed, and qRT-PCR and Western blot were conducted for the detection of Numb expression. Tumorigenicity assay in nude mice was carried out to verify the influence of blocker of the Numb/Notch signaling pathway on the radiosensitivity of xenograft tumors. The MTT assay, colony formation assay and flow cytometry experiments revealed that proliferation decreased as radiation dose increased. The viability of PANC-1 cells at 5 Gy, SW 1990 cells at 4 Gy and 5 Gy, and MIA PaCa-2 cells at 2-5 Gy was significantly lower than that of non-irradiated cells (all P < 0.05). The migration and invasion assays indicated that the PANC-1 cell line was least radiosensitive, while the MIA PaCa-2 cell line was the most radiosensitive. Numb expression significantly increased with increasing radiation dose, whereas the expression of Hes1, Notch1, and Hes5 significantly decreased compared to non-irradiated cells (P < 0.05). Compared to untreated control cells, DAPT dose dependently increased Numb expression and inhibited Notch1, Hes1, and Hes5 expressions at 2 Gy (P < 0.05). Subcutaneous tumorigenicity assay in nude mice demonstrated that DAPT increased the radiosensitivity of PANC-1, SW 1990, and MIA PaCa-2 cells. These findings suggest that Numb/Notch signaling in pancreatic cancer cells is associated with X-ray radiation and that inhibition of the Numb/Notch signaling pathway can enhance radiosensitivity, suggesting that inhibition of the Numb/Notch signaling pathway may serve as a potential

  5. Motoneuron BDNF/TrkB signaling enhances functional recovery after cervical spinal cord injury.

    PubMed

    Mantilla, Carlos B; Gransee, Heather M; Zhan, Wen-Zhi; Sieck, Gary C

    2013-09-01

    A C2 cervical spinal cord hemisection (SH) interrupts descending inspiratory-related drive to phrenic motoneurons located between C3 and C5 in rats, paralyzing the ipsilateral hemidiaphragm muscle. There is gradual recovery of rhythmic diaphragm muscle activity ipsilateral to cervical spinal cord injury over time, consistent with neuroplasticity and strengthening of spared, contralateral descending premotor input to phrenic motoneurons. Brain-derived neurotrophic factor (BDNF) signaling through the tropomyosin related kinase receptor subtype B (TrkB) plays an important role in neuroplasticity following spinal cord injury. We hypothesized that 1) increasing BDNF/TrkB signaling at the level of the phrenic motoneuron pool by intrathecal BDNF delivery enhances functional recovery of rhythmic diaphragm activity after SH, and 2) inhibiting BDNF/TrkB signaling by quenching endogenous neurotrophins with the soluble fusion protein TrkB-Fc or by knocking down TrkB receptor expression in phrenic motoneurons using intrapleurally-delivered siRNA impairs functional recovery after SH. Diaphragm EMG electrodes were implanted bilaterally to verify complete hemisection at the time of SH and 3days post-SH. After SH surgery in adult rats, an intrathecal catheter was placed at C4 to chronically infuse BDNF or TrkB-Fc using an implanted mini-osmotic pump. At 14days post-SH, all intrathecal BDNF treated rats (n=9) displayed recovery of ipsilateral hemidiaphragm EMG activity, compared to 3 out of 8 untreated SH rats (p<0.01). During eupnea, BDNF treated rats exhibited 76±17% of pre-SH root mean squared EMG vs. only 5±3% in untreated SH rats (p<0.01). In contrast, quenching endogenous BDNF with intrathecal TrkB-Fc treatment completely prevented functional recovery up to 14days post-SH (n=7). Immunoreactivity of the transcription factor cAMP response element-binding protein (CREB), a downstream effector of TrkB signaling, increased in phrenic motoneurons following BDNF treatment (n=6

  6. Newly synthesized quinazolinone HMJ-38 suppresses angiogenetic responses and triggers human umbilical vein endothelial cell apoptosis through p53-modulated Fas/death receptor signaling

    SciTech Connect

    Chiang, Jo-Hua; Yang, Jai-Sing; Lu, Chi-Cheng; Hour, Mann-Jen; Chang, Shu-Jen; Lee, Tsung-Han; Chung, Jing-Gung

    2013-06-01

    The current study aims to investigate the antiangiogenic responses and apoptotic death of human umbilical vein endothelial cells (HUVECs) by a newly synthesized compound named 2-(3′-methoxyphenyl)-6-pyrrolidinyl-4-quinazolinone (HMJ-38). This work attempted to not only explore the effects of angiogenesis on in vivo and ex vivo studies but also hypothesize the implications for HUVECs (an ideal cell model for angiogenesis in vitro) and further undermined apoptotic experiments to verify the underlying molecular signaling by HMJ-38. Our results demonstrated that HMJ-38 significantly inhibited blood vessel growth and microvessel formation by the mouse Matrigel plug assay of angiogenesis, and the suppression of microsprouting from the rat aortic ring assay was observed after HMJ-38 exposure. In addition, HMJ-38 disrupted the tube formation and blocked the ability of HUVECs to migrate in response to VEGF. We also found that HMJ-38 triggered cell apoptosis of HUVECs in vitro. HMJ-38 concentration-dependently suppressed viability and induced apoptotic damage in HUVECs. HMJ-38-influenced HUVECs were performed by determining the oxidative stress (ROS production) and ATM/p53-modulated Fas and DR4/DR5 signals that were examined by flow cytometry, Western blotting, siRNA and real-time RT-PCR analyses, respectively. Our findings demonstrate that p53-regulated extrinsic pathway might fully contribute to HMJ-38-provoked apoptotic death in HUVECs. In view of these observations, we conclude that HMJ-38 reduces angiogenesis in vivo and ex vivo as well as induces apoptosis of HUVECs in vitro. Overall, HMJ-38 has a potent anti-neovascularization effect and could warrant being a vascular targeting agent in the future. - Highlights: • HMJ-38 suppresses angiogenic actions in vivo and ex vivo. • Inhibitions of blood vessel and microvessel formation by HMJ-38 are acted. • Cytotoxic effects of HUVECs occur by HMJ-38 challenge. • p53-modulated extrinsic pathway contributes to HMJ-38

  7. Enhancement of arachidonic acid signaling pathway by nicotinic acid receptor HM74A.

    PubMed

    Tang, Yuting; Zhou, Lubing; Gunnet, Joseph W; Wines, Pamela G; Cryan, Ellen V; Demarest, Keith T

    2006-06-23

    HM74A is a G protein-coupled receptor for nicotinic acid (niacin), which has been used clinically to treat dyslipidemia for decades. The molecular mechanisms whereby niacin exerts its pleiotropic effects on lipid metabolism remain largely unknown. In addition, the most common side effect in niacin therapy is skin flushing that is caused by prostaglandin release, suggesting that the phospholipase A(2) (PLA(2))/arachidonic acid (AA) pathway is involved. Various eicosanoids have been shown to activate peroxisome-proliferator activated receptors (PPAR) that play a diverse array of roles in lipid metabolism. To further elucidate the potential roles of HM74A in mediating the therapeutic effects and/or side effects of niacin, we sought to explore the signaling events upon HM74A activation. Here we demonstrated that HM74A synergistically enhanced UTP- and bradykinin-mediated AA release in a pertussis toxin-sensitive manner in A431 cells. Activation of HM74A also led to Ca(2+)-mobilization and enhanced bradykinin-promoted Ca(2+)-mobilization through Gi protein. While HM74A increased ERK1/2 activation by the bradykinin receptor, it had no effects on UTP-promoted ERK1/2 activation.Furthermore, UTP- and bradykinin-mediated AA release was significantly decreased in the presence of both MAPK kinase inhibitor PD 098059 and PKC inhibitor GF 109203X. However, the synergistic effects of HM74A were not dramatically affected by co-treatment with both inhibitors, indicating the cross-talk occurred at the receptor level. Finally, stimulation of A431 cells transiently transfected with PPRE-luciferase with AA significantly induced luciferase activity, mimicking the effects of PPARgamma agonist rosiglitazone, suggesting that alteration of AA signaling pathway can regulate gene expression via endogenous PPARs.

  8. Enhancement of arachidonic acid signaling pathway by nicotinic acid receptor HM74A

    SciTech Connect

    Tang, Yuting . E-mail: ytang@prdus.jnj.com; Zhou, Lubing; Gunnet, Joseph W.; Wines, Pamela G.; Cryan, Ellen V.; Demarest, Keith T.

    2006-06-23

    HM74A is a G protein-coupled receptor for nicotinic acid (niacin), which has been used clinically to treat dyslipidemia for decades. The molecular mechanisms whereby niacin exerts its pleiotropic effects on lipid metabolism remain largely unknown. In addition, the most common side effect in niacin therapy is skin flushing that is caused by prostaglandin release, suggesting that the phospholipase A{sub 2} (PLA{sub 2})/arachidonic acid (AA) pathway is involved. Various eicosanoids have been shown to activate peroxisome-proliferator activated receptors (PPAR) that play a diverse array of roles in lipid metabolism. To further elucidate the potential roles of HM74A in mediating the therapeutic effects and/or side effects of niacin, we sought to explore the signaling events upon HM74A activation. Here we demonstrated that HM74A synergistically enhanced UTP- and bradykinin-mediated AA release in a pertussis toxin-sensitive manner in A431 cells. Activation of HM74A also led to Ca{sup 2+}-mobilization and enhanced bradykinin-promoted Ca{sup 2+}-mobilization through Gi protein. While HM74A increased ERK1/2 activation by the bradykinin receptor, it had no effects on UTP-promoted ERK1/2 activation.Furthermore, UTP- and bradykinin-mediated AA release was significantly decreased in the presence of both MAPK kinase inhibitor PD 098059 and PKC inhibitor GF 109203X. However, the synergistic effects of HM74A were not dramatically affected by co-treatment with both inhibitors, indicating the cross-talk occurred at the receptor level. Finally, stimulation of A431 cells transiently transfected with PPRE-luciferase with AA significantly induced luciferase activity, mimicking the effects of PPAR{gamma} agonist rosiglitazone, suggesting that alteration of AA signaling pathway can regulate gene expression via endogenous PPARs.

  9. The pepper GNA-related lectin and PAN domain protein gene, CaGLP1, is required for plant cell death and defense signaling during bacterial infection.

    PubMed

    Kim, Nak Hyun; Lee, Dong Hyuk; Choi, Du Seok; Hwang, Byung Kook

    2015-12-01

    Carbohydrate-binding proteins, commonly referred to as lectins or agglutinins, function in defense responses to microbial pathogens. Pepper (Capsicum annuum) GNA-related lectin and PAN-domain protein gene CaGLP1 was isolated and functionally characterized from pepper leaves infected with Xanthomonas campestris pv. vesicatoria (Xcv). CaGLP1 contained an amine-terminus prokaryotic membrane lipoprotein lipid attachment site, a Galanthus nivalis agglutinin (GNA)-related lectin domain responsible for the recognition of high-mannose N-glycans, and a carboxyl-terminus PAN/apple domain. RNA gel blot and immunoblot analyses determined that CaGLP1 was strongly induced in pepper by compatible and incompatible Xcv infection. CaGLP1 protein localized primarily to the plasma membrane and exhibited mannose-binding specificity. CaGLP1-silenced pepper plants were more susceptible to compatible or incompatible Xcv infection compared with that of non-silenced control plants. CaGLP1 silencing in pepper leaves did not accumulate H2O2 and induce cell death during incompatible Xcv infection. Defense-related CaDEF1 (defensin) gene expression was significantly reduced in CaGLP1-silenced pepper plants. CaGLP1-overexpression in Arabidopsis thaliana enhanced resistance to Pseudomonas syringae pv. tomato. Defense-related AtPDF1.2 expression was elevated in CaGLP1-overexpression lines. Together, these results suggest that CaGLP1 is required for plant cell death and defense responses through the reactive oxygen species burst and downstream defense-related gene expression in response to bacterial pathogen challenge.

  10. Parg deficiency confers radio-sensitization through enhanced cell death in mouse ES cells exposed to various forms of ionizing radiation.

    PubMed

    Shirai, Hidenori; Fujimori, Hiroaki; Gunji, Akemi; Maeda, Daisuke; Hirai, Takahisa; Poetsch, Anna R; Harada, Hiromi; Yoshida, Tomoko; Sasai, Keisuke; Okayasu, Ryuichi; Masutani, Mitsuko

    2013-05-24

    Poly(ADP-ribose) glycohydrolase (Parg) is the main enzyme involved in poly(ADP-ribose) degradation. Here, the effects of Parg deficiency on sensitivity to low and high linear-energy-transfer (LET) radiation were investigated in mouse embryonic stem (ES) cells. Mouse Parg(-/-) and poly(ADP-ribose) polymerase-1 deficient (Parp-1(-/-)) ES cells were used and responses to low and high LET radiation were assessed by clonogenic survival and biochemical and biological analysis methods. Parg(-/-) cells were more sensitive to γ-irradiation than Parp-1(-/-) cells. Transient accumulation of poly(ADP-ribose) was enhanced in Parg(-/-) cells. Augmented levels of phosphorylated H2AX (γ-H2AX) from early phase were observed in Parg(-/-) ES cells. The induction level of p53 phophorylation at ser18 was similar in wild-type and Parp-1(-/-) cells and apoptotic cell death process was mainly observed in the both genotypes. These results suggested that the enhanced sensitivity of Parg(-/-) ES cells to γ-irradiation involved defective repair of DNA double strand breaks. The effects of Parg and Parp-1 deficiency on the ES cell response to carbon-ion irradiation (LET13 and 70 keV/μm) and Fe-ion irradiation (200 keV/μm) were also examined. Parg(-/-) cells were more sensitive to LET 70 keV/μm carbon-ion irradiation than Parp-1(-/-) cells. Enhanced apoptotic cell death also accompanied augmented levels of γ-H2AX in a biphasic manner peaked at 1 and 24h. The induction level of p53 phophorylation at ser18 was not different between wild-type and Parg(-/-) cells. The augmented level of poly(ADP-ribose) accumulation was noted after carbon-ion irradiation compared to γ-irradiation even in the wild-type cells. An enhanced poly(ADP-ribose) accumulation was further observed in Parg(-/-) cells. Both Parg(-/-) cells and Parp-1(-/-) cells did not show sensitization to Fe-ion irradiation. Parg deficiency sensitizes mouse ES cells to a wide therapeutic range of LET radiation through the effects on

  11. Sigma-1 receptor enhances neurite elongation of cerebellar granule neurons via TrkB signaling.

    PubMed

    Kimura, Yuriko; Fujita, Yuki; Shibata, Kumi; Mori, Megumi; Yamashita, Toshihide

    2013-01-01

    Sigma-1 receptor (Sig-1R) is an integral membrane protein predominantly expressed in the endoplasmic reticulum. Sig-1R demonstrates a high affinity to various synthetic compounds including well-known psychotherapeutic drugs in the central nervous system (CNS). For that, it is considered as an alternative target for psychotherapeutic drugs. On the cellular level, when Sig-1R is activated, it is known to play a role in neuroprotection and neurite elongation. These effects are suggested to be mediated by its ligand-operated molecular chaperone activity, and/or upregulation of various Ca(2+) signaling. In addition, recent studies show that Sig-1R activation induces neurite outgrowth via neurotrophin signaling. Here, we tested the hypothesis that Sig-1R activation promotes neurite elongation through activation of tropomyosin receptor kinase (Trk), a family of neurotrophin receptors. We found that 2-(4-morpholinethyl)1-phenylcyclohexanecarboxylate (PRE-084), a selective Sig-1R agonist, significantly promoted neurite outgrowth, and K252a, a Trk inhibitor, attenuated Sig-1R-mediated neurite elongation in cerebellar granule neurons (CGNs). Moreover, we revealed that Sig-1R interacts with TrkB, and PRE-084 treatment enhances phosphorylation of Y515, but not Y706. Thus, our results indicate that Sig-1R activation promotes neurite outgrowth in CGNs through Y515 phosphorylation of TrkB.

  12. Spatial covert attention increases contrast sensitivity across the CSF: support for signal enhancement

    NASA Technical Reports Server (NTRS)

    Carrasco, M.; Penpeci-Talgar, C.; Eckstein, M.

    2000-01-01

    This study is the first to report the benefits of spatial covert attention on contrast sensitivity in a wide range of spatial frequencies when a target alone was presented in the absence of a local post-mask. We used a peripheral precue (a small circle indicating the target location) to explore the effects of covert spatial attention on contrast sensitivity as assessed by orientation discrimination (Experiments 1-4), detection (Experiments 2 and 3) and localization (Experiment 3) tasks. In all four experiments the target (a Gabor patch ranging in spatial frequency from 0.5 to 10 cpd) was presented alone in one of eight possible locations equidistant from fixation. Contrast sensitivity was consistently higher for peripherally- than for neutrally-cued trials, even though we eliminated variables (distracters, global masks, local masks, and location uncertainty) that are known to contribute to an external noise reduction explanation of attention. When observers were presented with vertical and horizontal Gabor patches an external noise reduction signal detection model accounted for the cueing benefit in a discrimination task (Experiment 1). However, such a model could not account for this benefit when location uncertainty was reduced, either by: (a) Increasing overall performance level (Experiment 2); (b) increasing stimulus contrast to enable fine discriminations of slightly tilted suprathreshold stimuli (Experiment 3); and (c) presenting a local post-mask (Experiment 4). Given that attentional benefits occurred under conditions that exclude all variables predicted by the external noise reduction model, these results support the signal enhancement model of attention.

  13. Morphine- and CaMKII-dependent enhancement of GIRK channel signaling in hippocampal neurons.

    PubMed

    Nassirpour, Rounak; Bahima, Laia; Lalive, Arnaud L; Lüscher, Christian; Luján, Rafael; Slesinger, Paul A

    2010-10-06

    G-protein-gated inwardly rectifying potassium (GIRK) channels, which help control neuronal excitability, are important for the response to drugs of abuse. Here, we describe a novel pathway for morphine-dependent enhancement of GIRK channel signaling in hippocampal neurons. Morphine treatment for ∼20 h increased the colocalization of GIRK2 with PSD95, a dendritic spine marker. Western blot analysis and quantitative immunoelectron microscopy revealed an increase in GIRK2 protein and targeting to dendritic spines. In vivo administration of morphine also produced an upregulation of GIRK2 protein in the hippocampus. The mechanism engaged by morphine required elevated intracellular Ca(2+) and was insensitive to pertussis toxin, implicating opioid receptors that may couple to Gq G-proteins. Met-enkephalin, but not the μ-selective (DAMGO) and δ-selective (DPDPE) opioid receptor agonists, mimicked the effect of morphine, suggesting involvement of a heterodimeric opioid receptor complex. Peptide (KN-93) inhibition of CaMKII prevented the morphine-dependent change in GIRK localization, whereas expression of a constitutively activated form of CaMKII mimicked the effects of morphine. Coincident with an increase in GIRK2 surface expression, functional analyses revealed that morphine treatment increased the size of serotonin-activated GIRK currents and Ba(2+)-sensitive basal K(+) currents in neurons. These results demonstrate plasticity in neuronal GIRK signaling that may contribute to the abusive effects of morphine.

  14. Signal enhancement in cantilever magnetometry based on a co-resonantly coupled sensor

    PubMed Central

    Körner, Julia; Reiche, Christopher F; Gemming, Thomas; Büchner, Bernd; Gerlach, Gerald

    2016-01-01

    Summary Cantilever magnetometry is a measurement technique used to study magnetic nanoparticles. With decreasing sample size, the signal strength is significantly reduced, requiring advances of the technique. Ultrathin and slender cantilevers can address this challenge but lead to increased complexity of detection. We present an approach based on the co-resonant coupling of a micro- and a nanometer-sized cantilever. Via matching of the resonance frequencies of the two subsystems we induce a strong interplay between the oscillations of the two cantilevers, allowing for a detection of interactions between the sensitive nanocantilever and external influences in the amplitude response curve of the microcantilever. In our magnetometry experiment we used an iron-filled carbon nanotube acting simultaneously as nanocantilever and magnetic sample. Measurements revealed an enhancement of the commonly used frequency shift signal by five orders of magnitude compared to conventional cantilever magnetometry experiments with similar nanomagnets. With this experiment we do not only demonstrate the functionality of our sensor design but also its potential for very sensitive magnetometry measurements while maintaining a facile oscillation detection with a conventional microcantilever setup. PMID:27547621

  15. CBL enhances breast tumor formation by inhibiting tumor suppressive activity of TGF-β signaling.

    PubMed

    Kang, J M; Park, S; Kim, S J; Hong, H Y; Jeong, J; Kim, H-S; Kim, S-J

    2012-12-13

    Casitas B-lineage lymphoma (CBL) protein family functions as multifunctional adaptor proteins and E3 ubiquitin ligases that are implicated as regulators of signaling in various cell types. Recent discovery revealed mutations of proto-oncogenic CBL in the linker region and RING finger domain in human acute myeloid neoplasm, and these transforming mutations induced carcinogenesis. However, the adaptor function of CBL mediated signaling pathway during tumorigenesis has not been well characterized. Here, we show that CBL is highly expressed in breast cancer cells and significantly inhibits transforming growth factor-β (TGF-β) tumor suppressive activity. Knockdown of CBL expression resulted in the increased expression of TGF-β target genes, PAI-I and CDK inhibitors such as p15(INK4b) and p21(Cip1). Furthermore, we demonstrate that CBL is frequently overexpressed in human breast cancer tissues, and the loss of CBL decreases the tumorigenic activity of breast cancer cells in vivo. CBL directly binds to Smad3 through its proline-rich motif, thereby preventing Smad3 from interacting with Smad4 and blocking nuclear translocation of Smad3. CBL-b, one of CBL protein family, also interacted with Smad3 and knockdown of both CBL and CBL-b further enhanced TGF-β transcriptional activity. Our findings provide evidence for a previously undescribed mechanism by which oncogenic CBL can block TGF-β tumor suppressor activity.

  16. Generation and tunable enhancement of a sum-frequency signal in lithium niobate nanowires

    NASA Astrophysics Data System (ADS)

    Sergeyev, Anton; Reig Escalé, Marc; Grange, Rachel

    2017-02-01

    Recent developments in the fabrication of lithium niobate (LiNbO3) structures down to the nanoscale opens up novel applications of this versatile material in nonlinear optics. Current nonlinear optical studies in sub-micron waveguides are mainly restricted to the generation of second and third harmonics. In this work, we demonstrate the generation and waveguiding of the sum-frequency generation (SFG) signal in a single LiNbO3 nanowire with a cross-section of 517 nm  ×  654 nm. Furthermore, we enhance the guided SFG signal 17.9 times by means of modal phase matching. We also display tuning of the phase-matched wavelength by varying the nanowire cross-section and changing the polarization of the incident laser. The results prove that LiNbO3 nanowires can be successfully used for nonlinear wave-mixing applications and assisting the miniaturization of optical devices. , which features invited work from the best early-career researchers working within the scope of J Phys D. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Rachel Grange was selected by the Editorial Board of J Phys D as an Emerging Leader.

  17. Asporin enhances colorectal cancer metastasis through activating the EGFR/Src/cortactin signaling pathway

    PubMed Central

    He, Yonggang; Hu, Lei; Wu, Haoxuan; Ye, Feng; Zhao, Ren

    2016-01-01

    Asporin has been implicated as an oncogene in various types of human cancers; however, the roles of asporin in the development and progression of colorectal cancer (CRC) have not yet been determined. With clinical samples, we found that asporin was highly expressed in CRC tissues compared to adjacent normal tissues and the asporin expression levels were significantly associated with lymph node metastasis status and TNM stage of the patients. Through knockdown of asporin in CRC cell lines RKO and SW620 or overexpression of asporin in cell lines HT-29 and LoVo, we found that asporin could enhance wound healing, migration and invasion abilities of the CRC cells. Further more, with the human umbilical vein endothelial cells (HUVECs) tube formation assays and the xenograft model, we found that asporin promoted the tumor growth through stimulating the VEGF signaling pathway. The portal vein injection models suggested that asporin overexpression stimulated the liver metastasis of HT29 cell line, while asporin knockdown inhibited the liver metastasis of RKO cell line. In addition, asporin was found to augment the phosphorylation of EGFR/Src/cortactin signaling pathway, which might be contributed to the biological functions of asporin in CRC metastasis. These results suggested that asporin promoted the tumor growth and metastasis of CRC, and it could be a potential therapeutic target for CRC patients in future. PMID:27705916

  18. Blockade of IL-18 signaling diminished neuropathic pain and enhanced the efficacy of morphine and buprenorphine.

    PubMed

    Pilat, Dominika; Piotrowska, Anna; Rojewska, Ewelina; Jurga, Agnieszka; Ślusarczyk, Joanna; Makuch, Wioletta; Basta-Kaim, Agnieszka; Przewlocka, Barbara; Mika, Joanna

    2016-03-01

    Currently, the low efficacy of antinociceptive drugs for the treatment of neuropathic pain is a major therapeutic problem. Here, we show the potential role of interleukin (IL)-18 signaling in this phenomenon. IL-18 is an important molecule that performs various crucial functions, including the alteration of nociceptive transmission in response to neuropathic pain. We have studied the changes in the mRNA and protein levels (qRT-PCR and Western blot analysis, respectively) of IL-18, IL-18-binding protein (IL-18BP) and the IL-18 receptor (IL-18R) over time in rats following chronic constriction injury (CCI) of the sciatic nerve. Our study demonstrated that the spinal levels of IL-18BP were slightly downregulated at days 7 and 14 in the rats subjected to CCI. In contrast, the IL-18 and IL-18R mRNA expression and protein levels were elevated in the ipsilateral spinal cord on days 2, 7 and 14. Moreover, in rats exposed to a single intrathecal administration of IL-18BP (50 and 100 ng) 7 or 14 days following CCI, symptoms of neuropathic pain were attenuated, and the analgesia pursuant to morphine and buprenorphine (0.5 and 2.5 μg) was enhanced. In summary, the restoration of the analgesic activity of morphine and buprenorphine via the blockade of IL-18 signaling suggests that increased IL-18 pathway may account for the decreased analgesic efficacy of opioids for neuropathic pain.

  19. Betaine supplementation enhances anabolic endocrine and Akt signaling in response to acute bouts of exercise.

    PubMed

    Apicella, Jenna M; Lee, Elaine C; Bailey, Brooke L; Saenz, Catherine; Anderson, Jeffrey M; Craig, Stuart A S; Kraemer, William J; Volek, Jeff S; Maresh, Carl M

    2013-03-01

    Our aim was to examine the effect of betaine supplementation on selected circulating hormonal measures and Akt muscle signaling proteins after an acute exercise session. Twelve trained men (age 19.7 ± 1.23 years) underwent 2 weeks of supplementation with either betaine (B) (1.25 g BID) or placebo (P). Following a 2-week washout period, subjects underwent supplementation with the other treatment (B or P). Before and after each 2-week period, subjects performed an acute exercise session (AES). Circulating GH, IGF-1, cortisol, and insulin were measured. Vastus lateralis samples were analyzed for signaling proteins (Akt, p70 S6k, AMPK). B (vs. P) supplementation approached a significant increase in GH (mean ± SD (Area under the curve, AUC), B: 40.72 ± 6.14, P: 38.28 ± 5.54, p = 0.060) and significantly increased IGF-1 (mean ± SD (AUC), B: 106.19 ± 13.45, P: 95.10 ± 14.23, p = 0.010), but significantly decreased cortisol (mean ± SD (AUC), B: 1,079.18 ± 110.02, P: 1,228.53 ± 130.32, p = 0.007). There was no difference in insulin (AUC). B increased resting Total muscle Akt (p = 0.003). B potentiated phosphorylation (relative to P) of Akt (Ser(473)) and p70 S6 k (Thr(389)) (p = 0.016 and p = 0.005, respectively). Phosphorylation of AMPK (Thr(172)) decreased during both treatments (both p = 0.001). Betaine (vs. placebo) supplementation enhanced both the anabolic endocrine profile and the corresponding anabolic signaling environment, suggesting increased protein synthesis.

  20. Novel MYH11 and ACTA2 mutations reveal a role for enhanced TGFβ signaling in FTAAD

    PubMed Central

    Renard, Marjolijn; Callewaert, Bert; Baetens, Machteld; Campens, Laurence; MacDermot, Kay; Fryns, Jean-Pierre; Bonduelle, Maryse; Dietz, Hal; Gaspar, Isabel Mendes; Cavaco, Diogo; Stattin, Eva-Lena; Schrander-Stumpel, Constance; Coucke, Paul; Loeys, Bart; De Paepe, Anne; De Backer, Julie

    2011-01-01

    Background Thoracic aortic aneurysm / dissection (TAAD) is a common phenotype that may occur as an isolated manifestation or within the constellation of a defined syndrome. In contrast to syndromic TAAD, the elucidation of the genetic basis of isolated TAAD has only recently started. To date, defects have been found in genes encoding extracellular matrix proteins (fibrillin-1, FBN1; collagen type III alpha 1, COL3A1), proteins involved in transforming growth factor beta (TGFβ) signaling (TGFβ receptor 1 and 2, TGFBR1/2; and SMAD3) or proteins that build up the contractile apparatus of aortic smooth muscle cells (myosin heavy chain 11, MYH11; smooth muscle actin alpha 2, ACTA2; and MYLK). Methods and results In 110 non-syndromic TAAD patients that previously tested negative for FBN1 or TGFBR1/2 mutations, we identified 7 ACTA2 mutations in a cohort of 43 familial TAAD patients, including 2 premature truncating mutations. Sequencing of MYH11 revealed an in frame splice-site alteration in one out of two probands with TAA(D) associated with PDA but none in the series of 22 probands from the cohort of 110 patients with non-syndromic TAAD. Interestingly, immunohistochemical staining of aortic biopsies of a patient and a family member with MYH11 and patients with ACTA2 missense mutations showed upregulation of the TGFβ signaling pathway. Conclusions MYH11 mutations are rare and typically identified in patients with TAAD associated with PDA. ACTA2 mutations were identified in 16% of a cohort presenting familial TAAD. Different molecular defects in TAAD may account for a different pathogenic mechanism of enhanced TGFβ signaling. PMID:21937134

  1. Enhancing kidney function with thrombolytic therapy following donation after cardiac death: a multicenter quasi-blinded prospective randomized trial.

    PubMed

    Woodside, Kenneth J; Goldfarb, David A; Rabets, John C; Sanchez, Edmund Q; Lebovitz, Daniel J; Schulak, James A; Fung, John J; Eghtesad, Bijan

    2015-12-01

    Kidneys from donors after cardiac death (DCD) are at risk for inferior outcomes, possibly due to microthrombi and additional warm ischemia. We describe an organ procurement organization-wide trial utilizing thrombolytic tissue plasminogen activator (tPA) during machine pulsatile perfusion (MPP). A kidney from each recovered kidney pair was prospectively randomized to receive tPA (50 mg Alteplase) or no tPA (control) in the MPP perfusate. From 2011 to 2013, 24 kidneys were placed with enrolled recipients from 19 DCD kidney donors. There were no significant differences for absolute values of flow or resistance while undergoing MPP between the groups, nor rates of achieving discrete flow and resistance targets. While there was a trend toward lower creatinine and higher glomerular filtration rates in the tPA group at 3, 6, 9, and 12 months, these differences were not significant. Delayed graft function (DGF) rates were 41.7% in the tPA group vs. 58.4% in the control group (OR 0.51, 95%CI 0.10-2.59, p = 0.68). Death-censored graft survival was similar between the groups. In this pilot study, encouraging trends are seen in kidney allograft function independent of MPP parameters following DCD kidney transplantation for those kidneys receiving thrombolytic tPA and MPP, compared with standard MPP.

  2. The organ preservation and enhancement of donation success ratio effect of extracorporeal membrane oxygenation in circulatory unstable brain death donor.

    PubMed

    Fan, Xiaoli; Chen, Zhiquan; Nasralla, David; Zeng, Xianpeng; Yang, Jing; Ye, Shaojun; Zhang, Yi; Peng, Guizhu; Wang, Yanfeng; Ye, Qifa

    2016-10-01

    Between 2010 and 2013, we recorded 66 cases of failed organ donation after brain death (DBD) due to the excessive use of the vasoactive drugs resulting in impaired hepatic and/or renal function. To investigate the effect of extracorporeal membrane oxygenation (ECMO) in donor management, ECMO was used to provide support for DBD donors with circulatory and/or respiratory failure from 2013 to 2015. A retrospective cohort study between circulatory non-stable DBD with vasoactive drugs (DBD-drug) and circulatory non-stable DBD with ECMO (DBD-ECMO) was designed to compare the transplant outcomes. A total of 19 brain death donors were supported by ECMO. The incidence rate of post-transplant liver primary non-function (PNF) was 10% (two of 20) in DBD-drug group and zero in DBD-ECMO group. Kidney function indicators, including creatinine clearance and urine production, were significantly better in DBD-ECMO group, as well as the kidney delayed graft function (DGF) rate was found to be decreased by the use of ECMO in our study. Donation success rate increased steadily from 47.8% in 2011 to 84.6% in 2014 after the ECMO intervention. The use of ECMO in assisting circulatory and respiratory function of DBD can reduce liver and kidney injury from vasoactive drugs, thereby improving organ quality and reducing the organ discard rates.

  3. Collision-induced signal enhancement: a method to increase product ion intensities in MS/MS and MSn experiments.

    PubMed

    Asam, M R; Ray, K L; Glish, G L

    1998-05-01

    Collision-induced signal enhancement (CISE), a new technique to enhance the MSn capabilities of the quadrupole ion trap, is demonstrated. CISE is based on the chemistry, i.e., the dissociation pathways, of the analyte examined. Polysaccharides up to hexamers are used to demonstrate the capabilities of CISE to enhance signal in two distinct functional modes. Mode 1 CISE is designed to enhance the signal of an ion desired for MSn analysis. Mode 2 CISE is designed to enhance structurally significant product ions in an MS/MS spectrum. Two different approaches can be utilized to effect the two functional modes of CISE. Both approaches use conventional resonant excitation techniques to effect dissociation, which is performed nonanalytically, i.e., without isolation of the ions to be dissociated. The two approaches are (1) single-frequency resonance excitation, and (2) broad-band wave form resonant excitation. Experimental results for Mode 1 CISE analysis demonstrate up to a 17.3-fold signal increase for the single-frequency approach and 5.3-fold using broad-band excitation. Mode 2 CISE analysis shows up to a 16.3-fold increase in signal strength with single-frequency excitation and 3.3-fold using broad-band excitation.

  4. Combination of Oral Vitamin D3 with Photodynamic Therapy Enhances Tumor Cell Death in a Murine Model of Cutaneous Squamous Cell Carcinoma

    PubMed Central

    Anand, Sanjay; Rollakanti, Kishore R.; Horst, Ronald L.; Hasan, Tayyaba; Maytin, Edward V.

    2014-01-01

    Photodynamic therapy (PDT), in which 5-ALA (a precursor for protoporphyrin IX, PpIX) is administered prior to exposure to light, is a nonscarring treatment for skin cancers. However, for deep tumors, ALA-PDT is not always effective due to inadequate production of PpIX. We previously developed and reported a combination approach in which the active form of vitamin D3 (calcitriol) is given systemically prior to PDT to improve PpIX accumulation and to enhance PDT-induced tumor cell death; calcitriol, however, poses a risk of hypercalcemia. Here, we tested a possible strategy to circumvent the problem of hypercalcemia by substituting natural dietary vitamin D3 (cholecalciferol; D3) for calcitriol. Oral D3 supplementation (10 days of a 10-fold elevated D3 diet) enhanced PpIX levels 3- to 4-fold, and PDT-mediated cell death 20-fold, in subcutaneous A431 tumors. PpIX levels and cell viability in normal tissues were not affected. Hydroxylated metabolic forms of D3 were only modestly elevated in serum, indicating minimal hypercalcemic risk. These results show that brief oral administration of cholecalciferol can serve as a safe neoadjuvant to ALA-PDT. We suggest a clinical study, using oral vitamin D3 prior to PDT, should be considered to evaluate this promising new approach to treating human skin cancer. PMID:24807677

  5. Enhancing Endocrine Therapy for Hormone Receptor-Positive Advanced Breast Cancer: Cotargeting Signaling Pathways.

    PubMed

    Johnston, Stephen R D

    2015-10-01

    Overcoming primary or secondary endocrine resistance in breast cancer remains critical to further enhancing the benefit of existing therapies such as tamoxifen or an aromatase inhibitor (AI). Much progress has been made in understanding the molecular biology associated with secondary endocrine resistance. Cotargeting the estrogen receptor, together with various key intracellular proliferation and cell survival signaling pathways, has been explored as a strategy either to treat endocrine resistance once it develops in the second-line setting or to enhance first-line endocrine responsiveness by preventing secondary resistance from developing via blockade of specific pathways from the outset. While attempts to improve endocrine therapy by adding growth factor inhibitors have been disappointing, success resulting in new drug approvals has been seen in secondary endocrine resistance by treating patients with the mTOR antagonist everolimus in combination with the AI exemestane and, more recently, in the first-line setting, by the addition of the CDK 4/6 inhibitor palbociclib to the AI letrozole. Numerous other therapeutics are being evaluated in combination with endocrine therapies based on supportive preclinical evidence, including inhibitors of PI3K, Akt, HDAC, Src, IGFR-1, and FGFR. Appropriate clinical trial design and patient selection based on prior therapy exposure, together with predictive biomarkers derived through real-time molecular profiling, are needed to enrich future trials and maximize any additional benefit that cotargeting may bring to current endocrine therapies for estrogen receptor-positive breast cancer.

  6. cAMP enhances BMP2-signaling through PKA and MKP1-dependent mechanisms

    SciTech Connect

    Ghayor, Chafik; Ehrbar, Martin; Miguel, Blanca San; Graetz, Klaus W.; Weber, Franz E.

    2009-04-03

    Recent studies suggest that the elevation of intracellular cyclic adenosine monophosphate (cAMP) and the activation of the protein kinase A regulate BMP-induced osteogenesis. However, the precise mechanisms underlying the enhancing effect of cAMP on BMP2 signaling were not completely revealed. In this study we investigated the effect of elevated cAMP level and PKA activation on the BMP2-induced osteoblastic differentiation in pluripotent C2C12 cells. Alkaline phosphatase activity and its mRNA were consistently induced by BMP2 treatment. The pretreatment of C2C12 cells with Forskolin, a cAMP generating agent, dbcAMP, an analogue of cAMP, or IBMX (3-isobutyl 1-methyl xanthine), and a nonspecific inhibitor of phosphodiesterases elicited further activation of alkaline phosphatase. Furthermore, elevated intracellular cAMP level increased BMP2-induced MKP1. On the other hand, BMP2-induced Erk phosphorylation (p44/p42) and cell proliferation were suppressed in the presence of cAMP. Thus, cAMP might enhance BMP2-induced osteoblastic differentiation by a MKP1-Erk-dependent mechanism.

  7. Arctigenin, a Natural Lignan Compound, Induces Apoptotic Death of Hepatocellular Carcinoma Cells via Suppression of PI3-K/Akt Signaling.

    PubMed

    Jiang, Xiaoxin; Zeng, Leping; Huang, Jufang; Zhou, Hui; Liu, Yubin

    2015-04-28

    In this study, we explored the cytotoxic effects of arctigenin, a natural lignan compound, on human hepatocellular carcinoma (HCC) cells and check the involvement of phosphatidylinositol 3-kinase (PI3-K)/Akt signaling. HCC cells were treated with different concentrations of arctigenin and cell viability and apoptosis were assessed. Manipulating Akt signaling was used to determine its role in the action of arctigenin. Arctigenin significantly inhibited the viability of HCC cells in a concentration-dependent manner. Arctigenin induced apoptosis and activation of caspase-9 and -3. Overexpression of a constitutively active Akt mutant blocked arctigenin-induced apoptosis. Combinational treatment with arctigenin and the PI3-K inhibitor LY294002 significantly enhanced apoptosis. Arctigenin reduced the expression of Bcl-xL, Mcl-1, and survivin and the phosphorylation of mTOR and S6K, which were significantly reversed by overexpression of constitutively active Akt. This is the first report about the anticancer activity of arctigenin in HCC cells, which is mediated by inactivation of PI3-K/Akt signaling.

  8. Tunnel barrier enhanced voltage signals generated by magnetization precession of a single ferromagnetic layer

    NASA Astrophysics Data System (ADS)

    Moriyama, Takahiro

    2009-03-01

    A variety of experimentally observed phenomena involving nonlocal magnetization dynamics in magnetic multilayers are due to two complementary effects: (i) the transfer of spin angular momentum accompanying charge currents driven by the applied bias voltage between ferromagnetic layers results in torques that (for sufficiently high current densities) generate spontaneous magnetization precession and switching; and (ii) the precessing magnetization of a ferromagnet (FM) pumps spins into adjacent normal metal layers (NM) with no applied bias. In particular, the spin pumping effect is a promising candidate for realizing a spin battery device [1] as a source of elusive pure spin currents (not accompanied by any net charge transport) emitted at the FM/NM interface, where steady magnetization precession of the FM layer is sustained by the absorption of external rf radiation under the FMR conditions. We report the electrical detection of magnetization dynamics in an Al/AlOx/Ni80Fe20/Cu tunnel junction, where a Ni80Fe20 ferromagnetic layer is brought into precession under the ferromagnetic resonance (FMR) conditions. The dc voltage generated across the junction by the precessing ferromagnet is enhanced about an order of magnitude compared to the voltage signal observed in Cu/FeNi/Pt structures [2]. A structure of Cu (100nm)/Al (10nm)/AlOx (2.3nm)/Ni80Fe20 (20nm)/Cu (70nm)/Au (25nm) was fabricated on a Si substrate with a 1μm thick thermal oxide layer. The bottom-most 100 nm Cu layer was patterned into a coplanar waveguide (CPW) and the rest of the structure was patterned into a pillar structure on the signal line of the CPW. Dc voltages ˜μV were observed in the Al/AlOx/Ni80Fe20/Cu tunnel junction when the Ni80Fe20 is in the ferromagnetic resonance. The dc voltages increase as the precession cone angle and frequency increase. We discuss the relation of this phenomenon to magnetic spin pumping and speculate on other possible underlying mechanisms responsible for the

  9. Inhibition on Numb/Notch signal pathway enhances radiosensitivity of lung cancer cell line H358.

    PubMed

    Song, Shi-Gang; Yu, Hong-Yang; Ma, Yan-Wei; Zhang, Feng; Xu, Xiang-Ying

    2016-10-01

    The objective of the study is to investigate the effects of the Numb/Notch signal pathway on the radiosensitivity of lung cancer cell line H358. MTT assay and colony forming assay were used to detect the effects of different doses of X-rays and MW167 on the in vitro proliferation of the lung cancer cell line H358. Flow cytometry was applied to evaluate the effects of X rays on the apoptosis of H358. Scratch assay and Transwell invasion assay were used to examine the effects of X-rays on the migration and invasion abilities of H358. The mRNA and protein expressions in the signal pathway were detected by real-time PCR and western blot. Assays in vitro confirmed the effects of the Numb/Notch pathway inhibitor on the radiosensitivity to lung cancer. MW167 enhanced the inhibiting effects of X-ray on the proliferation of H358 cell line. After the addition of MW167, the apoptosis rates significantly increased, but the invasion and migration abilities decreased significantly. Meanwhile, MW167 could dose-dependently promote the increase of expression of Numb, which is the upstream gene of the Numb/Notch signaling pathway, but inhibit the expression of and HES1. In vivo experiments revealed that cell proliferation was suppressed in the radiation, pathway inhibitor, and pathway inhibitor + radiation groups, and the pathway inhibitor + radiation group exhibited more active anti-tumor ability when compared with the blank group (all P < 0.05); Numb expression was up-regulated, but Notch1 and HES1 expressions were down-regulated in those three groups, and also, the pathway inhibitor + radiation group exhibited more significant alternation when compared with the blank group (all P < 0.05); cell apoptosis was promoted in those three groups, and the pathway inhibitor + radiation group showed more active apoptosis when compared with the blank group (all P < 0.05). Repression of the Numb/Notch pathway enhances the effects of radiotherapy on the radiosensitivity of the lung

  10. Dendritic cell vaccines based on immunogenic cell death elicit danger signals and T cell-driven rejection of high-grade glioma.

    PubMed

    Garg, Abhishek D; Vandenberk, Lien; Koks, Carolien; Verschuere, Tina; Boon, Louis; Van Gool, Stefaan W; Agostinis, Patrizia

    2016-03-02

    The promise of dendritic cell (DC)-based immunotherapy has been established by two decades of translational research. Of the four malignancies most targeted with clinical DC immunotherapy, high-grade glioma (HGG) has shown the highest susceptibility. HGG-induced immunosuppression is a roadblock to immunotherapy, but may be overcome by the application of T helper 1 (T(H)1) immunity-biased, next-generation, DC immunotherapy. To this end, we combined DC immunotherapy with immunogenic cell death (ICD; a modality shown to induce T(H)1 immunity) induced by hypericin-based photodynamic therapy. In an orthotopic HGG mouse model involving prophylactic/curative setups, both biologically and clinically relevant versions of ICD-based DC vaccines provided strong anti-HGG survival benefit. We found that the ability of DC vaccines to elicit HGG rejection was significantly blunted if cancer cell-associated reactive oxygen species and emanating danger signals were blocked either singly or concomitantly, showing hierarchical effect on immunogenicity, or if DCs, DC-associated MyD88 signal, or the adaptive immune system (especially CD8(+) T cells) were depleted. In a curative setting, ICD-based DC vaccines synergized with standard-of-care chemotherapy (temozolomide) to increase survival of HGG-bearing mice by ~300%, resulting in ~50% long-term survivors. Additionally, DC vaccines also induced an immunostimulatory shift in the brain immune contexture from regulatory T cells to T(H)1/cytotoxic T lymphocyte/T(H)17 cells. Analysis of the The Cancer Genome Atlas glioblastoma cohort confirmed that increased intratumor prevalence of T(H)1/cytotoxic T lymphocyte/T(H)17 cells linked genetic signatures was associated with good patient prognosis. Therefore, pending final preclinical checks, ICD-based vaccines can be clinically translated for glioma treatment.

  11. PTEN regulates apoptotic cell death through PI3-K/Akt/GSK3β signaling pathway in DMH induced early colon carcinogenesis in rat.

    PubMed

    Saini, Manpreet Kaur; Sanyal, Sankar Nath

    2012-08-01

    Phosphatidylinositol 3-kinase (PI3-K) and Akt (protein kinase B), are both essential signaling molecules that are up-regulated in various cancers. Here, we examined the molecular mechanisms by which PI3-K and Akt expression are regulated by glycogen synthase kinase-3β (GSK-3β) and the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in the early stages of experimental colon carcinogenesis. 1,2-dimethylhydrazine (DMH) was utilized for the induction of colon cancer while piroxicam, a traditional non-steroidal anti-inflammatory drug and c-phycocyanin, a biliprotein from Spirulina platensis (cyanobacterium) as the chemopreventive agents. Western blotting and immunofluorescence results indicated that the expression of PI3-K and Akt was promoted in the DMH group while least apoptosis was detected in this group as analyzed by Hoechst 33342-propidium iodide co-staining. DMH group further detected lower GSK-3β and PTEN expression as compared to other groups. Piroxicam and c-phycocyanin treatment resulted significant apoptotic cell death while showing low PI3-K and Akt expressions. Mitochondrial membrane potential (ΔΨ(M)) alterations (examined by JC-1 and rhodamine 123 labeling of colonocytes) and fluorescence intensity measurement of ROS level, were also analyzed showing the raised ΔΨ(M) while reduced ROS levels in DMH group, however piroxicam and c-phycocyanin treatment resulted in falling of ΔΨ(M) although both stimulated the ROS production as analyzed by flow cytometry. The present study thus identified that piroxicam, a traditional NSAID and c-phycocyanin, a newly discovered COX-2 selective inhibitor, constitute remarkable chemopreventive targets in mediating apoptosis in the DMH induced early rat colon carcinogenesis via regulating PI3-K/Akt/GSK-3β/PTEN signaling pathways. Further, a combination of the two drugs provides a better therapeutic option, than the monotherapy regimen.

  12. Clinical Light Exposure, Photoreceptor Degeneration, and AP-1 Activation: A Cell Death or Cell Survival Signal in the Rhodopsin Mutant Retina?

    PubMed Central

    Gu, Danian; Beltran, William A.; Li, Zexiao; Acland, Gregory M.; Aguirre, Gustavo D.

    2008-01-01

    Purpose The T4R RHO mutant dog retina shows retinal degeneration with exposures to light comparable to those used in clinical eye examinations of patients. To define the molecular mechanisms of the degeneration, AP-1 DNA-binding activity, composition, posttranslational modification of the protein complex, and modulation of ERK/MAPK signaling pathways were examined in light-exposed mutant retinas. Methods Dark-adapted retinas were exposed to short-duration light flashes from a retinal camera used clinically for retinal photography and were collected at different time points after exposure. Electrophoretic mobility shift assay (EMSA), super-shift EMSA, Western blot analysis, and immunocytochemistry were used to examine AP-1 signaling. Results Exposure to light of mutant retinas significantly increased AP-1 DNA-binding activity by 1 hour after exposure, and levels remained elevated for 6 hours. Shielded mutant retinas had similar AP-1 levels to shielded or exposed wild-type retinas. The parallel phosphorylation of c-Fos and activation of ERK1/2 was detected only in exposed mutant retinas. Exposure to light changed the composition of the AP-1 protein complex in the mutant retina from c-Jun/Fra-1/c-Fos to JunB/c-Fos. Immunohistochemistry showed that the components of activated AP-1 (JunB, and phosphorylated c-Fos, and phosphorylated ERK1/2 isoforms) were localized in Müller cells. Conclusions The inner nuclear layer/Müller cell localization of the key proteins induced by light exposure raises the question of the direct involvement of AP-1 in mediating photoreceptor cell death in this model of autosomal dominant retinitis pigmentosa. PMID:17962438

  13. Galloflavin, a new lactate dehydrogenase inhibitor, induces the death of human breast cancer cells with different glycolytic attitude by affecting distinct signaling pathways.

    PubMed

    Farabegoli, F; Vettraino, M; Manerba, M; Fiume, L; Roberti, M; Di Stefano, G

    2012-11-20

    Galloflavin (GF), a recently identified lactate dehydrogenase inhibitor, hinders the proliferation of cancer cells by blocking glycolysis and ATP production. The aim of the present experiments was to study the effect of this compound on breast cancer cell lines reproducing different pathological subtypes of this tumor: MCF-7 (the well differentiated form), MDA-MB-231 (the aggressive triple negative tumor) and MCF-Tam (a sub-line of MCF-7 with acquired tamoxifen resistance). We observed marked differences in the energetic metabolism of these cell lines. Compared to MCF-7 cells, both MDA-MB-231 and MCF-Tam cells exhibited higher LDH levels and glucose uptake and showed lower capacity of oxygen consumption. In spite of these differences, GF exerted similar growth inhibitory effects. This result was explained by the finding of a constitutively activated stress response in MDA-MB-231 and MCF-Tam cells, which reproduce the poor prognosis tumor forms. As a further proof, different signaling pathways were found to be involved in the antiproliferative action of GF. In MCF-7 cells we observed a down regulation of the ERα-mediated signaling needed for cell survival. On the contrary, in MCF-Tam and MDA-MB-231 cells growth inhibition appeared to be contributed by an oxidative stress condition. The prevalent mechanism of cell death was found to be apoptosis induction. Because of the clinical relevance of breast cancer forms having the triple negative and/or chemoresistant phenotype, our results showing comparable effects of GF even on aggressively growing cells encourage further studies to verify the potential of this compound in improving the chemotherapy of breast cancer.

  14. Genistein inhibition of OGD-induced brain neuron death correlates with its modulation of apoptosis, voltage-gated potassium and sodium currents and glutamate signal pathway.

    PubMed

    Ma, Xue-Ling; Zhang, Feng; Wang, Yu-Xiang; He, Cong-Cong; Tian, Kun; Wang, Hong-Gang; An, Di; Heng, Bin; Liu, Yan-Qiang

    2016-07-25

    In the present study, we established an in vitro model of hypoxic-ischemia via exposing primary neurons of newborn rats to oxygen-glucose deprivation (OGD) and observing the effects of genistein, a soybean isoflavone, on hypoxic-ischemic neuron viability, apoptosis, voltage-activated potassium (Kv) and sodium (Nav) currents, and glutamate receptor subunits. The results indicated that OGD exposure reduced the viability and increased the apoptosis of brain neurons. Meanwhile, OGD exposure caused changes in the current-voltage curves and current amplitude values of voltage-activated potassium and sodium currents; OGD exposure also decreased GluR2 expression and increased NR2 expression. However, genistein at least partially reversed the effects caused by OGD. The results suggest that hypoxic-ischemia-caused neuronal apoptosis/death is related to an increase in K(+) efflux, a decrease in Na(+) influx, a down-regulation of GluR2, and an up-regulation of NR2. Genistein may exert some neuroprotective effects via the modulation of Kv and Nav currents and the glutamate signal pathway, mediated by GluR2 and NR2.

  15. Artificial rearing inhibits apoptotic cell death through action on pro-apoptotic signaling molecules during brain development: replacement licking partially reverses these effects.

    PubMed

    Chatterjee-Chakraborty, Munmun; Chatterjee, Diptendu

    2010-08-12

    Early life stress associated with being reared without mother, siblings, and nest affects the formation of neuronal networks during rat development. Prior work shows that in comparison to mother-reared male rats, artificial rearing results in elevated numbers of neurons in adulthood and reduced apoptosis during the first postnatal week. Replacement with stroking stimulation, designed to simulate mothers' licking, reversed these effects in most brain areas. The present communication explored the effects of early rearing manipulations on signaling proteins. Male rats were reared until postnatal day 7 either in an artificial-feeding paradigm (AR) or with their mothers (MR). AR animals received different amounts of maternal-like stimulation using a soft paintbrush. Brains were extracted and prepared for molecular assays of 1) apoptosis and 2) pro and anti-apoptotic proteins on day 7 of postnatal life. Results showed that stimulation of the AR pups reversed the effects of artificial rearing on apoptosis in a dose dependent manner; low and very high levels of stimulation were without effect whereas moderate levels of stimulation produced effects on apoptosis similar to effects seen in mother-reared controls. Moreover, this artificial rearing effect and the pattern of reversal with stroking were also found for levels of pro-apoptotic Bax protein, the ratio of Bax/Bcl-2 and levels of activated caspase-3 which we believe mediates programmed cell death.

  16. Resveratrol mediates cell cycle arrest and cell death in human esophageal squamous cell carcinoma by directly targeting the EGFR signaling pathway

    PubMed Central

    Jin, Zixuan; Feng, Wei; Ji, Ying; Jin, Longyu

    2017-01-01

    Resveratrol is a small polyphenol that has been intensively studied in a wide spectrum of therapeutic fields. More recently, resveratrol has been demonstrated to exert its antitumor activity in numerous tumor models. The present study reported that resveratrol exhibited a marked anti-proliferative effect on human esophageal squamous cell carcinoma (ESCC) cells by inducing cell cycle G0/G1 phase arrest and cell death, which was associated with a decrease in the expression levels of cyclin D1 and an increase in cleaved PARP/cleaved caspase-3 expression levels. The mechanisms underlying the antitumor potency of resveratrol were principally attributed to the downregulation of epidermal growth factor receptor (EGFR) signaling. The western blotting results showed that exposure of ESCC cells to resveratrol inhibited EGF-induced EGFR activation in addition to decreasing the total protein levels of EGFR and membrane/nuclear localization. In summary, the results suggested that resveratrol, or an associated analog, may have a role in the management of human ESCC. PMID:28123566

  17. KLF15 protects against isoproterenol-induced cardiac hypertrophy via regulation of cell death and inhibition of Akt/mTOR signaling.

    PubMed

    Gao, Li; Guo, Yudong; Liu, Xiaofeng; Du, Yongjian

    2017-03-20

    Increasing evidence indicate that the Krüppel-like factor KLF15, a member of Cys2/His2 zinc-finger DNA-binding proteins, attenuates cardiac hypertrophy. However, the role of KLF15 in cardiovascular system is largely unknown and the exact molecular mechanism of its protective function is not fully elucidated. In the present study, we established a mouse model of cardiac hypertrophy and found that KLF15 expression was down-regulated in hypertrophic hearts. To evaluate the roles of KLF15 in cardiac hypertrophy, we generated transgenic mice overexpressing KLF15 of KLF15 knockdown mice and subsequently induced cardiac hypertrophy. The results indicated that KLF15 overexpression protects mice from ISO-induced cardiac hypertrophy, with reduced ratios of heart weight (HW)/body weight (BW) and cross-sectional area. We also observed that KLF15 overexpression attenuated cardiac fibrosis, inhibited apoptosis and induced autophagy in cardiomyocytes compared with KLF15 knockdown mice. More importantly, we found that the KLF15 overexpression inhibited the Akt/mTOR signaling pathway. Taken together, our findings imply that KLF15 possesses potential anti-hypertrophic and anti-fibrotic functions, possibly via regulation of cell death pathways and the inhibition of Akt/mTOR axis. KLF15 may constitute an efficient candidate drug for the treatment of heart failure and other cardiovascular diseases.

  18. Calculation of intravascular signal in dynamic contrast enhanced-MRI using adaptive complex independent component analysis.

    PubMed

    Mehrabian, Hatef; Chopra, Rajiv; Martel, Anne L

    2013-04-01

    Assessing tumor response to therapy is a crucial step in personalized treatments. Pharmacokinetic (PK) modeling provides quantitative information about tumor perfusion and vascular permeability that are associated with prognostic factors. A fundamental step in most PK analyses is calculating the signal that is generated in the tumor vasculature. This signal is usually inseparable from the extravascular extracellular signal. It was shown previously using in vivo and phantom experiments that independent component analysis (ICA) is capable of calculating the intravascular time-intensity curve in dynamic contrast enhanced (DCE)-MRI. A novel adaptive complex independent component analysis (AC-ICA) technique is developed in this study to calculate the intravascular time-intensity curve and separate this signal from the DCE-MR images of tumors. The use of the complex-valued DCE-MRI images rather than the commonly used magnitude images satisfied the fundamental assumption of ICA, i.e., linear mixing of the sources. Using an adaptive cost function in ICA through estimating the probability distribution of the tumor vasculature at each iteration resulted in a more robust and accurate separation algorithm. The AC-ICA algorithm provided a better estimate for the intravascular time-intensity curve than the previous ICA-based method. A simulation study was also developed in this study to realistically simulate DCE-MRI data of a leaky tissue mimicking phantom. The passage of the MR contrast agent through the leaky phantom was modeled with finite element analysis using a diffusion model. Once the distribution of the contrast agent in the imaging field of view was calculated, DCE-MRI data was generated by solving the Bloch equation for each voxel at each time point. The intravascular time-intensity curve calculation results were compared to the previously proposed ICA-based intravascular time-intensity curve calculation method that applied ICA to the magnitude of the DCE-MRI data

  19. Shiga toxin-2 enhances heat-shock-induced apoptotic cell death in cultured and primary glial cells.

    PubMed

    Sugimoto, Naotoshi; Toma, Tomoko; Shimizu, Masaki; Kuroda, Mondo; Wada, Taizo; Yachie, Akihiro

    2014-10-01

    The blood-brain barrier (BBB) selectively controls the homeostasis of the central nervous system (CNS) environment using specific structural and biochemical features of the endothelial cells, pericytes, and glial limitans. Glial cells, which represent the cellular components of the mature BBB, are the most numerous cells in the brain and are indispensable for neuronal functioning. We investigated the effects of Shiga toxin on glial cells in vitro. Shiga toxin failed to inhibit cell proliferation but attenuated expression of heat shock protein 70, which is one of the chaperone proteins, in cultured and primary glial cells. Furthermore, the combination of Shiga toxin and a heat shock procedure induced cell apoptosis and decreased cell proliferation in both cells. Thus, we speculate that glial cell death in response to the combination of Shiga toxin and heat shock might weaken the BBB and induce central nervous system complications.

  20. Fluorescence signals of core-shell quantum dots enhanced by single crystalline gold caps on silicon nanowires

    NASA Astrophysics Data System (ADS)

    Christiansen, S. H.; Chou, J. W.; Becker, M.; Sivakov, V.; Ehrhold, K.; Berger, A.; Chou, W. C.; Chuu, D. S.; Gösele, U.

    2009-04-01

    We use nanoscale (20-300 nm in diameter) single crystalline gold (Au)-caps on silicon nanowires (NWs) grown by the vapor-liquid-solid (VLS) growth mechanism to enhance the fluorescence photoluminescence (PL) signals of highly dilute core/shell CdSeTe/ZnS quantum dots (QDs) in aqueous solution (10-5 M). For NWs without Au-caps, as they appear, for example, after Au etching in aqua regia or buffered KI/I2-solution, essentially no fluorescence signal of the same diluted QDs could be observed. Fluorescence PL signals were measured using excitation with a laser wavelength of 633 nm. The signal enhancement by single crystalline, nanoscale Au-caps is discussed and interpreted based on finite element modeling (FEM).

  1. Cot Deaths.

    ERIC Educational Resources Information Center

    Tyrrell, Shelagh

    1985-01-01

    Addresses the tragedy of crib deaths, giving particular attention to causes, prevention, and medical research on Sudden Infant Death Syndrome (SIDS). Gives anecdotal accounts of coping strategies used by parents and families of SIDS infants. (DT)

  2. Enhancement of Raman scattering signals from gaseous medium near the surface of a holographic aluminum diffraction grating

    NASA Astrophysics Data System (ADS)

    Petrov, D. V.; Sedinkin, D. O.; Zaripov, A. R.

    2016-11-01

    The possibility of applying surface-enhanced Raman scattering (RS) for amplification of RS intensity in gaseous media is investigated. A more than sixfold enhancement of the RS signal is detected experimentally from the main atmospheric air components during interaction of continuous-wave laser radiation with a holographic aluminum diffraction grating. The averaged value of the RS signals' amplification factor in the near-surface 30-nm-thick layer at the boundary between the diffraction grating and gaseous medium amounted to 3 × 103.

  3. Improved Long-Term Memory via Enhancing cGMP-PKG Signaling Requires cAMP-PKA Signaling

    PubMed Central

    Bollen, Eva; Puzzo, Daniela; Rutten, Kris; Privitera, Lucia; De Vry, Jochen; Vanmierlo, Tim; Kenis, Gunter; Palmeri, Agostino; D'Hooge, Rudi; Balschun, Detlef; Steinbusch, Harry MW; Blokland, Arjan; Prickaerts, Jos

    2014-01-01

    Memory consolidation is defined by the stabilization of a memory trace after acquisition, and consists of numerous molecular cascades that mediate synaptic plasticity. Commonly, a distinction is made between an early and a late consolidation phase, in which early refers to the first hours in which labile synaptic changes occur, whereas late consolidation relates to stable and long-lasting synaptic changes induced by de novo protein synthesis. How these phases are linked at a molecular level is not yet clear. Here we studied the interaction of the cyclic nucleotide-mediated pathways during the different phases of memory consolidation in rodents. In addition, the same pathways were studied in a model of neuronal plasticity, long-term potentiation (LTP). We demonstrated that cGMP/protein kinase G (PKG) signaling mediates early memory consolidation as well as early-phase LTP, whereas cAMP/protein kinase A (PKA) signaling mediates late consolidation and late-phase-like LTP. In addition, we show for the first time that early-phase cGMP/PKG signaling requires late-phase cAMP/PKA-signaling in both LTP and long-term memory formation. PMID:24813825

  4. The death receptor antagonist FAIM promotes neurite outgrowth by a mechanism that depends on ERK and NF-κB signaling

    PubMed Central

    Sole, Carme; Dolcet, Xavier; Segura, Miguel F.; Gutierrez, Humberto; Diaz-Meco, Maria-Teresa; Gozzelino, Raffaella; Sanchis, Daniel; Bayascas, Jose R.; Gallego, Carme; Moscat, Jorge; Davies, Alun M.; Comella, Joan X.

    2004-01-01

    Fas apoptosis inhibitory molecule (FAIM) is a protein identified as an antagonist of Fas-induced cell death. We show that FAIM overexpression fails to rescue neurons from trophic factor deprivation, but exerts a marked neurite growth–promoting action in different neuronal systems. Whereas FAIM overexpression greatly enhanced neurite outgrowth from PC12 cells and sympathetic neurons grown with nerve growth factor (NGF), reduction of endogenous FAIM levels by RNAi decreased neurite outgrowth in these cells. FAIM overexpression promoted NF-κB activation, and blocking this activation by using a super-repressor IκBα or by carrying out experiments using cortical neurons from mice that lack the p65 NF-κB subunit prevented FAIM-induced neurite outgrowth. The effect of FAIM on neurite outgrowth was also blocked by inhibition of the Ras–ERK pathway. Finally, we show that FAIM interacts with both Trk and p75 neurotrophin receptor NGF receptors in a ligand-dependent manner. These results reveal a new function of FAIM in promoting neurite outgrowth by a mechanism involving activation of the Ras–ERK pathway and NF-κB. PMID:15520226

  5. Bone marrow-derived mesenchymal stem cells enhance autophagy via PI3K/AKT signalling to reduce the severity of ischaemia/reperfusion-induced lung injury.

    PubMed

    Li, Jing; Zhou, Jian; Zhang, Dan; Song, Yuanlin; She, Jun; Bai, Chunxue

    2015-10-01

    Autophagy, a type II programmed cell death, is essential for cell survival under stress, e.g. lung injury, and bone marrow-derived mesenchymal stem cells (BM-MSCs) have great potential for cell therapy. However, the mechanisms underlying the BM-MSC activation of autophagy to provide a therapeutic effect in ischaemia/reperfusion-induced lung injury (IRI) remain unclear. Thus, we investigate the activation of autophagy in IRI following transplantation with BM-MSCs. Seventy mice were pre-treated with BM-MSCs before they underwent lung IRI surgery in vivo. Human pulmonary micro-vascular endothelial cells (HPMVECs) were pre-conditioned with BM-MSCs by oxygen-glucose deprivation/reoxygenation (OGD) in vitro. Expression markers for autophagy and the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signalling pathway were analysed. In IRI-treated mice, administration of BM-MSCs significantly attenuated lung injury and inflammation, and increased the level of autophagy. In OGD-treated HPMVECs, co-culture with BM-MSCs attenuated endothelial permeability by decreasing the level of cell death and enhanced autophagic activation. Moreover, administration of BM-MSCs decreased the level of PI3K class I and p-Akt while the expression of PI3K class III was increased. Finally, BM-MSCs-induced autophagic activity was prevented using the inhibitor LY294002. Administration of BM-MSCs attenuated lung injury by improving the autophagy level via the PI3K/Akt signalling pathway. These findings provide further understanding of the mechanisms related to BM-MSCs and will help to develop new cell-based therapeutic strategies in lung injury.

  6. Bone marrow-derived mesenchymal stem cells enhance autophagy via PI3K/AKT signalling to reduce the severity of ischaemia/reperfusion-induced lung injury

    PubMed Central

    Li, Jing; Zhou, Jian; Zhang, Dan; Song, Yuanlin; She, Jun; Bai, Chunxue

    2015-01-01

    Autophagy, a type II programmed cell death, is essential for cell survival under stress, e.g. lung injury, and bone marrow-derived mesenchymal stem cells (BM-MSCs) have great potential for cell therapy. However, the mechanisms underlying the BM-MSC activation of autophagy to provide a therapeutic effect in ischaemia/reperfusion-induced lung injury (IRI) remain unclear. Thus, we investigate the activation of autophagy in IRI following transplantation with BM-MSCs. Seventy mice were pre-treated with BM-MSCs before they underwent lung IRI surgery in vivo. Human pulmonary micro-vascular endothelial cells (HPMVECs) were pre-conditioned with BM-MSCs by oxygen-glucose deprivation/reoxygenation (OGD) in vitro. Expression markers for autophagy and the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signalling pathway were analysed. In IRI-treated mice, administration of BM-MSCs significantly attenuated lung injury and inflammation, and increased the level of autophagy. In OGD-treated HPMVECs, co-culture with BM-MSCs attenuated endothelial permeability by decreasing the level of cell death and enhanced autophagic activation. Moreover, administration of BM-MSCs decreased the level of PI3K class I and p-Akt while the expression of PI3K class III was increased. Finally, BM-MSCs-induced autophagic activity was prevented using the inhibitor LY294002. Administration of BM-MSCs attenuated lung injury by improving the autophagy level via the PI3K/Akt signalling pathway. These findings provide further understanding of the mechanisms related to BM-MSCs and will help to develop new cell-based therapeutic strategies in lung injury. PMID:26177266

  7. Filtering of the Radon transform to enhance linear signal features via wavelet pyramid decomposition

    NASA Astrophysics Data System (ADS)

    Meckley, John R.

    1995-09-01

    The information content in many signal processing applications can be reduced to a set of linear features in a 2D signal transform. Examples include the narrowband lines in a spectrogram, ship wakes in a synthetic aperture radar image, and blood vessels in a medical computer-aided tomography scan. The line integrals that generate the values of the projections of the Radon transform can be characterized as a bank of matched filters for linear features. This localization of energy in the Radon transform for linear features can be exploited to enhance these features and to reduce noise by filtering the Radon transform with a filter explicitly designed to pass only linear features, and then reconstructing a new 2D signal by inverting the new filtered Radon transform (i.e., via filtered backprojection). Previously used methods for filtering the Radon transform include Fourier based filtering (a 2D elliptical Gaussian linear filter) and a nonlinear filter ((Radon xfrm)**y with y >= 2.0). Both of these techniques suffer from the mismatch of the filter response to the true functional form of the Radon transform of a line. The Radon transform of a line is not a point but is a function of the Radon variables (rho, theta) and the total line energy. This mismatch leads to artifacts in the reconstructed image and a reduction in achievable processing gain. The Radon transform for a line is computed as a function of angle and offset (rho, theta) and the line length. The 2D wavelet coefficients are then compared for the Haar wavelets and the Daubechies wavelets. These filter responses are used as frequency filters for the Radon transform. The filtering is performed on the wavelet pyramid decomposition of the Radon transform by detecting the most likely positions of lines in the transform and then by convolving the local area with the appropriate response and zeroing the pyramid coefficients outside of the response area. The response area is defined to contain 95% of the total

  8. Integration of differentiation signals during indirect flight muscle formation by a novel enhancer of Drosophila vestigial gene.

    PubMed

    Bernard, Frédéric; Kasherov, Petar; Grenetier, Sabrina; Dutriaux, Annie; Zider, Alain; Silber, Joël; Lalouette, Alexis

    2009-08-15

    The gene vestigial (vg) plays a key role in indirect flight muscle (IFM) development. We show here that vg is controlled by the Notch anti-myogenic signaling pathway in myoblasts and is regulated by a novel 822 bp enhancer during IFM differentiation. Interestingly, this muscle enhancer is activated in developing fibers and in a small number of myoblasts before the fusion of myoblasts with the developing muscle fibers. Moreover, we show that this enhancer is activated by Drosophila Myocyte enhancing factor 2 (MEF2), Scalloped (SD) and VG but repressed by Twist, demonstrating a sensitivity to differentiation in vivo. In vitro experiments reveal that SD can directly bind this enhancer and MEF2 can physically interact with both SD and TWI. Cumulatively, our data reveal the interplay between different myogenic factors responsible for the expression of an enhancer activated during muscle differentiation.

  9. Resveratrol enhances ultraviolet B-induced cell death through nuclear factor-{kappa}B pathway in human epidermoid carcinoma A431 cells

    SciTech Connect

    Roy, Preeti; Kalra, Neetu; Nigam, Nidhi; George, Jasmine; Ray, Ratan Singh; Hans, Rajendra K.; Prasad, Sahdeo; Shukla, Yogeshwer

    2009-06-26

    Resveratrol has been reported to suppress cancer progression in several in vivo and in vitro models, whereas ultraviolet B (UVB), a major risk for skin cancer, is known to induce cell death in cancerous cells. Here, we investigated whether resveratrol can sensitize A431 human epidermoid carcinoma cells to UVB-induced cell death. We examined the combined effect of UVB (30 mJ/cm{sup 2}) and resveratrol (60 {mu}M) on A431 cells. Exposure of A431 carcinoma cells to UVB radiation or resveratrol can inhibit cell proliferation and induce apoptosis. However, the combination of resveratrol and UVB exposure was associated with increased proliferation inhibition of A431 cells compared with either agent alone. Furthermore, results showed that resveratrol and UVB treatment of A431 cells disrupted the nuclear factor-kappaB (NF-{kappa}B) pathway by blocking phosphorylation of serine 536 and inactivating NF-{kappa}B and subsequent degradation of I{kappa}B{alpha}, which regulates the expression of survivin. Resveratrol and UVB treatment also decreased the phosphorylation of tyrosine 701 of the important transcription factor signal transducer activator of transcription (STAT1), which in turn inhibited translocation of phospho-STAT1 to the nucleus. Moreover, resveratrol/UVB also inhibited the metastatic protein LIMK1, which reduced the motility of A431 cells. In conclusion, our study demonstrates that the combination of resveratrol and UVB act synergistically against skin cancer cells. Thus, resveratrol is a potential chemotherapeutic agent against skin carcinogenesis.

  10. Interleukin-6 enhances porcine parthenote development in vitro, through the IL-6/Stat3 signaling pathway.

    PubMed

    Shen, Xing-Hui; Cui, Xiang-Shun; Lee, Sung-Hyun; Kim, Nam-Hyung

    2012-01-01

    Signal transducer and activator of transcription-3 (Stat3) plays a central role in interleukin-6 (IL-6)-mediated cell proliferation by inhibiting apoptosis in a variety of cell types. The Stat3 pathway is essential for embryonic development. The aim of this study was to determine the effects of recombinant IL-6 on the viability and development of porcine diploid parthenotes cultured in vitro. Four-cell parthenotes, derived in vitro, were cultured to the blastocyst s