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Sample records for activates signal transduction

  1. Signal transduction activated by cannabinoid receptors.

    PubMed

    Díaz-Laviada, Inés; Ruiz-Llorente, Lidia

    2005-07-01

    Since the discovery that cannabinoids exert biological actions through binding to specific receptors, signal mechanisms triggered by these receptors have been focus of extensive study. This review summarizes the current knowledge of the signalling events produced by cannabinoids from membrane receptors to downstream regulators. Two types of cannabinoid receptors have been identified to date: CB(1) and CB(2) both belonging to the heptahelichoidal receptor family but with different tissue distribution and signalling mechanisms. Coupling to inhibitory guanine nucleotide-binding protein and thus inhibition of adenylyl cyclase has been observed in both receptors but other signal transduction pathways that are regulated or not by these G proteins are differently activated upon ligand-receptor binding including ion channels, sphingomyelin hydrolysis, ceramide generation, phospholipases activation and downstream targets as MAP kinase cascade, PI3K, FAK or NOS regulation. Cannabinoids may also act independently of CB(1)or CB(2) receptors. The existence of new unidentified putative cannabinoid receptors has been claimed by many investigators. Endocannabinoids activate vanilloid TRPV1 receptors that may mediate some of the cannabinoid effects. Other actions of cannabinoids can occur through non-receptor-mediated mechanisms.

  2. Activity Dependent Signal Transduction in Skeletal Muscle

    NASA Technical Reports Server (NTRS)

    Hamilton, Susan L.

    1999-01-01

    The overall goals of this project are: 1) to define the initial signal transduction events whereby the removal of gravitational load from antigravity muscles, such as the soleus, triggers muscle atrophy, and 2) to develop countermeasures to prevent this from happening. Our rationale for this approach is that, if countermeasures can be developed to regulate these early events, we could avoid having to deal with the multiple cascades of events that occur downstream from the initial event. One of our major findings is that hind limb suspension causes an early and sustained increase in intracellular Ca(2+) concentration ([Ca (2+)](sub i)). In most cells the consequences of changes in ([Ca (2+)](sub i))depend on the amplitude, frequency and duration of the Ca(2+) signal and on other factors in the intracellular environment. We propose that muscle remodeling in microgravity represents a change in the balance among several CA(2+) regulated signal transduction pathways, in particular those involving the transcription factors NFAT and NFkB and the pro-apoptotic protein BAD. Other Ca(2+) sensitive pathways involving PKC, ras, rac, and CaM kinase II may also contribute to muscle remodeling.

  3. Mitogen-activated protein kinase and abscisic acid signal transduction.

    PubMed

    Heimovaara-Dijkstra, S; Testerink, C; Wang, M

    2000-01-01

    The phytohormone abscisic acid (ABA) is a classical plant hormone, responsible for regulation of abscission, diverse aspects of plant and seed development, stress responses and germination. It was found that ABA signal transduction in plants can involve the activity of type 2C-phosphatases (PP2C), calcium, potassium, pH and a transient activation of MAP kinase. The ABA signal transduction cascades have been shown to be tissue-specific, the transient activation of MAP kinase has until now only been found in barley aleurone cells. However, type 2C phosphatases are involved in the induction of most ABA responses, as shown by the PP2C-deficient abi-mutants. These phosphatases show high homology with phosphatases that regulate MAP kinase activity in yeast. In addition, the role of farnesyl transferase as a negative regulator of ABA responses also indicates towards involvement of MAP kinase in ABA signal transduction. Farnesyl transferase is known to regulate Ras proteins, Ras proteins in turn are known to regulate MAP kinase activation. Interestingly, Ras-like proteins were detected in barley aleurone cells. Further establishment of the involvement of MAP kinase in ABA signal transduction and its role therein, still awaits more study.

  4. Monocyte Signal Transduction Receptors in Active and Latent Tuberculosis

    PubMed Central

    Druszczynska, Magdalena; Wlodarczyk, Marcin; Janiszewska-Drobinska, Beata; Kielnierowski, Grzegorz; Zawadzka, Joanna; Kowalewicz-Kulbat, Magdalena; Fol, Marek; Szpakowski, Piotr; Rudnicka, Karolina; Chmiela, Magdalena; Rudnicka, Wieslawa

    2013-01-01

    The mechanisms that promote either resistance or susceptibility to TB disease remain insufficiently understood. Our aim was to compare the expression of cell signaling transduction receptors, CD14, TLR2, CD206, and β2 integrin LFA-1 on monocytes from patients with active TB or nonmycobacterial lung disease and healthy individuals with M.tb latency and uninfected controls to explain the background of the differences between clinical and subclinical forms of M.tb infection. A simultaneous increase in the expression of the membrane bound mCD14 receptor and LFA-1 integrin in patients with active TB may be considered a prodrome of breaking immune control by M.tb bacilli in subjects with the latent TB and absence of clinical symptoms. PMID:23401703

  5. CSF-1 signal transduction.

    PubMed

    Hamilton, J A

    1997-08-01

    Colony-stimulating factor-1 (CSF-1) or macrophage-CSF (M-CSF) is a growth factor involved in the proliferation, differentiation, and activation of cells of the monocyte/macrophage lineage. Its receptor is the homodimeric, tyrosine kinase product of the c-fms proto-oncogene, which contains a so-called kinase insert domain. This review focuses mainly on recent studies of signal transduction events that are initiated on interaction of CSF-1 and its receptor. A summary is given of the tyrosine autophosphorylation sites on c-Fms identified to date, including their interaction with various substrates and their possible significance for signal transduction and cellular function. In addition, the signal transduction pathways that have been identified to lie downstream of activated c-Fms are reviewed. Although it is apparent that there have been many recent significant developments in our understanding of CSF-1 signaling, a number of examples are mentioned of significant discrepancies in the literature, some possible reasons for which can sometimes be offered. It is also apparent that any particular biochemical response or signal transduction pathway, even though widespread in other ligand receptor/cellular systems, including those with similar receptor structures to c-Fms, may not be relevant to CSF-1 signaling. The relevance of any potentially important molecular signaling pathway activated by CSF-1 in cells in vitro will ultimately have to be related to the functions of monocytes/macrophages in vivo.

  6. Mitogen-activated protein kinase activation in UV-induced signal transduction.

    PubMed

    Bode, Ann M; Dong, Zigang

    2003-01-28

    Experimental evidence supported by epidemiological findings suggests that solar ultraviolet (UV) irradiation is the most important environmental carcinogen leading to the development of skin cancers. Because the ozone layer blocks UVC (wavelength, 180 to 280 nm) exposure, UVA (UVA I, 340 to 400 nm; UVA II, 320 to 340 nm) and UVB (280 to 320 nm) are probably the chief carcinogenic components of sunlight with relevance for human skin cancer. Substantial contributions to the elucidation of the specific signal transduction pathways involved in UV-induced skin carcinogenesis have been made over the past few years, and most evidence suggests that the cellular signaling response is UV wavelength-dependent. The mitogen-activated protein kinase (MAPK) signaling cascades are targets for UV and are important in the regulation of the multitude of UV-induced cellular responses. Experimental studies have used a range of UVA, UVB, UVC, and various combinations in multiple doses, and the observed effects on activation and phosphorylation of MAPKs are varied. This review focuses on the mechanistic data supporting a role for MAPKs in UV-induced skin carcinogenesis. Progress in understanding the mechanisms of UV-induced signal transduction could lead to the use of these protein kinases as specific targets for the prevention and control of skin cancer.

  7. Activation of the Syk tyrosine kinase is insufficient for downstream signal transduction in B lymphocytes

    PubMed Central

    Hsueh, Robert C; Hammill, Adrienne M; Lee, Jamie A; Uhr, Jonathan W; Scheuermann, Richard H

    2002-01-01

    Background Immature B lymphocytes and certain B cell lymphomas undergo apoptotic cell death following activation of the B cell antigen receptor (BCR) signal transduction pathway. Several biochemical changes occur in response to BCR engagement, including activation of the Syk tyrosine kinase. Although Syk activation appears to be necessary for some downstream biochemical and cellular responses, the signaling events that precede Syk activation remain ill defined. In addition, the requirements for complete activation of the Syk-dependent signaling step remain to be elucidated. Results A mutant form of Syk carrying a combination of a K395A substitution in the kinase domain and substitutions of three phenylalanines (3F) for the three C-terminal tyrosines was expressed in a murine B cell lymphoma cell line, BCL1.3B3 to interfere with normal Syk regulation as a means to examine the Syk activation step in BCR signaling. Introduction of this kinase-inactive mutant led to the constitutive activation of the endogenous wildtype Syk enzyme in the absence of receptor engagement through a 'dominant-positive' effect. Under these conditions, Syk kinase activation occurred in the absence of phosphorylation on Syk tyrosine residues. Although Syk appears to be required for BCR-induced apoptosis in several systems, no increase in spontaneous cell death was observed in these cells. Surprisingly, although the endogenous Syk kinase was enzymatically active, no enhancement in the phosphorylation of cytoplasmic proteins, including phospholipase Cγ2 (PLCγ2), a direct Syk target, was observed. Conclusion These data indicate that activation of Syk kinase enzymatic activity is insufficient for Syk-dependent signal transduction. This observation suggests that other events are required for efficient signaling. We speculate that localization of the active enzyme to a receptor complex specifically assembled for signal transduction may be the missing event. PMID:12470302

  8. Brassinosteroid Signal Transduction: From Receptor Kinase Activation to Transcriptional Networks Regulating Plant Development REVIEW

    PubMed Central

    Clouse, Steven D.

    2011-01-01

    Brassinosteroid (BR) signal transduction research has progressed rapidly from the initial discovery of the BR receptor to a complete definition of the basic molecular components required to relay the BR signal from perception by receptor kinases at the cell surface to activation of a small family of transcription factors that regulate the expression of more than a thousand genes in a BR-dependent manner. These mechanistic advances have helped answer the intriguing question of how a single molecule, such as a hormone, can have dramatic pleiotropic effects on a broad range of diverse developmental pathways and have shed light on how BRs interact with other plant hormones and environmental cues to shape the growth of the whole plant. This review summarizes the current state of BR signal transduction research and then examines recent articles uncovering gene regulatory networks through which BR influences both vegetative and reproductive development. PMID:21505068

  9. Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction.

    PubMed

    Beguerisse-Díaz, Mariano; Desikan, Radhika; Barahona, Mauricio

    2016-08-01

    Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction.

  10. Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction.

    PubMed

    Beguerisse-Díaz, Mariano; Desikan, Radhika; Barahona, Mauricio

    2016-08-01

    Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction. PMID:27581482

  11. Linear models of activation cascades: analytical solutions and coarse-graining of delayed signal transduction

    PubMed Central

    Desikan, Radhika

    2016-01-01

    Cellular signal transduction usually involves activation cascades, the sequential activation of a series of proteins following the reception of an input signal. Here, we study the classic model of weakly activated cascades and obtain analytical solutions for a variety of inputs. We show that in the special but important case of optimal gain cascades (i.e. when the deactivation rates are identical) the downstream output of the cascade can be represented exactly as a lumped nonlinear module containing an incomplete gamma function with real parameters that depend on the rates and length of the cascade, as well as parameters of the input signal. The expressions obtained can be applied to the non-identical case when the deactivation rates are random to capture the variability in the cascade outputs. We also show that cascades can be rearranged so that blocks with similar rates can be lumped and represented through our nonlinear modules. Our results can be used both to represent cascades in computational models of differential equations and to fit data efficiently, by reducing the number of equations and parameters involved. In particular, the length of the cascade appears as a real-valued parameter and can thus be fitted in the same manner as Hill coefficients. Finally, we show how the obtained nonlinear modules can be used instead of delay differential equations to model delays in signal transduction. PMID:27581482

  12. Distinct signal transduction pathways for activation of rabbit alveolar macrophages in vitro by cotton bract tannin.

    PubMed

    Prévost, M C; Soulat, J M; Comminges, C; Maury, E; Aslane, R; Cohen-Jonathan, E; Cariven, C; Lauque, D; Chap, H

    1996-05-01

    These experiments were designed to study signal transduction pathways in alveolar macrophages stimulated by condensed tannin or zymosan. Condensed tannins, present in cotton mill dust, alter the host-defense function of alveolar macrophages and may contribute to the pathogenesis of byssinosis. We tried to determine the early steps in signal transduction mechanisms of cell activation by tannin. With the quantification of 51Cr release, we determined that tannin was cytotoxic for the cells after 30 min activation with 130 micrograms for 2 x 10(6) cells. 51Cr release was similar for control cells and zymosan- or 30 micrograms tannin-activated cells. Using the luciferine luciferase reaction, we showed that tannin markedly depleted ATP cell content. In inositol-labeled cells, tannin increased inositolphosphate release in a dose-dependent manner. In lysoPAF-labeled cells, tannin induced synthesis of phosphatidic acid and diglycerides. In the presence of ethanol, the level of tannin-induced phosphatidic acid was slightly reduced, and phosphatidylethanol was synthesized. No phosphatidylethanol was found in alveolar macrophages stimulated by zymosan in the presence of ethanol. GF 109203X, a specific inhibitor of protein kinase C decreased only tannin-induced phosphatidylethanol synthesis. In conclusion, tannin (at 30 or 130 micrograms/ml) activated an inositol phospholipase C in alveolar membranes. Phosphatidylcholine phospholipases C and D were found only at the higher concentration of tannin.

  13. Meeting report: teaching signal transduction.

    PubMed

    Kramer, Ijsbrand; Thomas, Geraint

    2006-01-01

    In July, 2005, the European Institute of Chemistry and Biology at the campus of the University of Bordeaux, France, hosted a focused week of seminars, workshops, and discussions around the theme of "teaching signal transduction." The purpose of the summer school was to offer both junior and senior university instructors a chance to reflect on the development and delivery of their teaching activities in this area. This was achieved by combining open seminars with restricted access workshops and discussion events. The results suggest ways in which systems biology, information and communication technology, Web-based investigations, and high standard illustrations might be more effectively and efficiently incorporated into modern cell biology courses.

  14. Casein kinase 1 gamma couples Wnt receptor activation to cytoplasmic signal transduction.

    PubMed

    Davidson, Gary; Wu, Wei; Shen, Jinlong; Bilic, Josipa; Fenger, Ursula; Stannek, Peter; Glinka, Andrei; Niehrs, Christof

    2005-12-01

    Signalling by Wnt proteins (Wingless in Drosophila) has diverse roles during embryonic development and in adults, and is implicated in human diseases, including cancer. LDL-receptor-related proteins 5 and 6 (LRP5 and LRP6; Arrow in Drosophila) are key receptors required for transmission of Wnt/beta-catenin signalling in metazoa. Although the role of these receptors in Wnt signalling is well established, their coupling with the cytoplasmic signalling apparatus remains poorly defined. Using a protein modification screen for regulators of LRP6, we describe the identification of Xenopus Casein kinase 1 gamma (CK1gamma), a membrane-bound member of the CK1 family. Gain-of-function and loss-of-function experiments show that CK1gamma is both necessary and sufficient to transduce LRP6 signalling in vertebrates and Drosophila cells. In Xenopus embryos, CK1gamma is required during anterio-posterior patterning to promote posteriorizing Wnt/beta-catenin signalling. CK1gamma is associated with LRP6, which has multiple, modular CK1 phosphorylation sites. Wnt treatment induces the rapid CK1gamma-mediated phosphorylation of these sites within LRP6, which, in turn, promotes the recruitment of the scaffold protein Axin. Our results reveal an evolutionarily conserved mechanism that couples Wnt receptor activation to the cytoplasmic signal transduction apparatus. PMID:16341016

  15. Cadmium Induces Apoptosis in Freshwater Crab Sinopotamon henanense through Activating Calcium Signal Transduction Pathway

    PubMed Central

    Wang, Jinxiang; Zhang, Pingping; Liu, Na; Wang, Qian; Luo, Jixian; Wang, Lan

    2015-01-01

    Calcium ion (Ca2+) is one of the key intracellular signals, which is implicated in the regulation of cell functions such as impregnation, cell proliferation, differentiation and death. Cadmium (Cd) is a toxic environmental pollutant that can disturb cell functions and even lead to cell death. Recently, we have found that Cd induced apoptosis in gill cells of the freshwater crab Sinopotamon henanense via caspase activation. In the present study, we further investigated the role of calcium signaling in the Cd-induced apoptosis in the animals. Our data showed that Cd triggered gill cell apoptosis which is evidenced by apoptotic DNA fragmentation, activations of caspases-3, -8 and -9 and the presence of apoptotic morphological features. Moreover, Cd elevated the intracellular concentration of Ca2+, the protein concentration of calmodulin (CaM) and the activity of Ca2+-ATPase in the gill cells of the crabs. Pretreatment of the animals with ethylene glycol-bis-(b-aminoethyl ether)-N,N,N’,N’-tetraacetic acid (EGTA), Ca2+ chelator, inhibited Cd-induced activation of caspases-3, -8 and -9 as well as blocked the Cd-triggered apoptotic DNA fragmentation. The apoptotic morphological features were no longer observed in gill cells pretreated with the Ca2+ signaling inhibitors before Cd treatment. Our results indicate that Cd evokes gill cell apoptosis through activating Ca2+-CaM signaling transduction pathway. PMID:26714174

  16. Signal transduction pathways in mast cell granule-mediated endothelial cell activation.

    PubMed Central

    Chi, Luqi; Stehno-Bittel, Lisa; Smirnova, Irina; Stechschulte, Daniel J; Dileepan, Kottarappat N

    2003-01-01

    BACKGROUND: We have previously shown that incubation of human endothelial cells with mast cell granules results in potentiation of lipopolysaccharide-induced production of interleukin-6 and interleukin-8. AIMS: The objective of the present study was to identify candidate molecules and signal transduction pathways involved in the synergy between mast cell granules and lipopolysaccharide on endothelial cell activation. METHODS: Human umbilical vein endothelial cells were incubated with rat mast cell granules in the presence and absence of lipopolysaccharide, and IL-6 production was quantified. The status of c-Jun amino-terminal kinase and extracellular signal-regulated kinase 1/2 activation, nuclear factor-kappaB translocation and intracellular calcium levels were determined to identify the mechanism of synergy between mast cell granules and lipopolysaccaride. RESULTS: Mast cell granules induced low levels of interleukin-6 production by endothelial cells, and this effect was markedly enhanced by lipopolysaccharide. The results revealed that both serine proteases and histamine present in mast cell granules were involved in this activation process. Mast cell granules increased intracellular calcium, and activated c-Jun amino-terminal kinase and extracellular signal-regulated kinase 1/2. The combination of lipopolysaccharide and mast cell granules prolonged c-Jun amino-terminal kinase activity beyond the duration of induction by either stimulant alone and was entirely due to active proteases. However, both proteases and histamine contributed to calcium mobilization and extracellular signal-regulated kinase 1/2 activation. The nuclear translocation of nuclear factor-kappaB proteins was of greater magnitude in endothelial cells treated with the combination of mast cell granules and lipopolysaccharide. CONCLUSIONS:Mast cell granule serine proteases and histamine can amplify lipopolysaccharide-induced endothelial cell activation, which involves calcium mobilization, mitogen-activated

  17. Reliable Signal Transduction

    NASA Astrophysics Data System (ADS)

    Wollman, Roy

    Stochasticity inherent to biochemical reactions (intrinsic noise) and variability in cellular states (extrinsic noise) degrade information transmitted through signaling networks. We analyzed the ability of temporal signal modulation - that is dynamics - to reduce noise-induced information loss. In the extracellular signal-regulated kinase (ERK), calcium (Ca(2 +)) , and nuclear factor kappa-B (NF- κB) pathways, response dynamics resulted in significantly greater information transmission capacities compared to nondynamic responses. Theoretical analysis demonstrated that signaling dynamics has a key role in overcoming extrinsic noise. Experimental measurements of information transmission in the ERK network under varying signal-to-noise levels confirmed our predictions and showed that signaling dynamics mitigate, and can potentially eliminate, extrinsic noise-induced information loss. By curbing the information-degrading effects of cell-to-cell variability, dynamic responses substantially increase the accuracy of biochemical signaling networks.

  18. Signal transduction in the activation of spermatozoa compared to other signalling pathways: a biological networks study.

    PubMed

    Bernabò, Nicola; Mattioli, Mauro; Barboni, Barbara

    2015-01-01

    In this paper we represented Spermatozoa Activation (SA) the process that leads male gametes to reach their fertilising ability of sea urchin, Caenorhabditis elegans and human as biological networks, i.e. as networks of nodes (molecules) linked by edges (their interactions). Then, we compared them with networks representing ten pathways of relevant physio-pathological importance and with a computer-generated network. We have found that the number of nodes and edges composing each network is not related with the amount of published papers on each specific topic and that all the topological parameters examined are similar in all the networks, thus conferring them a scale free topology and small world behaviour. In conclusion, SA topology, independently from the reproductive biology of considered organism, as others signalling networks is characterised by robustness against random failure, controllability and efficiency in signal transmission. PMID:26489142

  19. Meeting Report: Teaching Signal Transduction

    PubMed Central

    Kramer, IJsbrand; Thomas, Geraint

    2006-01-01

    In July, 2005, the European Institute of Chemistry and Biology at the campus of the University of Bordeaux, France, hosted a focused week of seminars, workshops, and discussions around the theme of “teaching signal transduction.” The purpose of the summer school was to offer both junior and senior university instructors a chance to reflect on the development and delivery of their teaching activities in this area. This was achieved by combining open seminars with restricted access workshops and discussion events. The results suggest ways in which systems biology, information and communication technology, Web-based investigations, and high standard illustrations might be more effectively and efficiently incorporated into modern cell biology courses. PMID:17012185

  20. Interferon-gamma regulates nucleoside transport systems in macrophages through signal transduction and activator of transduction factor 1 (STAT1)-dependent and -independent signalling pathways.

    PubMed Central

    Soler, Concepció; Felipe, Antonio; García-Manteiga, José; Serra, Maria; Guillén-Gómez, Elena; Casado, F Javier; MacLeod, Carol; Modolell, Manuel; Pastor-Anglada, Marçal; Celada, Antonio

    2003-01-01

    The expressions of CNT and ENT (concentrative and equilibrative nucleoside transporters) in macrophages are differentially regulated by IFN-gamma (interferon-gamma). This cytokine controls gene expression through STAT1-dependent and/or -independent pathways (where STAT1 stands for signal transduction and activator of transcription 1). In the present study, the role of STAT1 in the response of nucleoside transporters to IFN-gamma was studied using macrophages from STAT1 knockout mice. IFN-gamma triggered an inhibition of ENT1-related nucleoside transport activity through STAT1-dependent mechanisms. Such inhibition of macrophage growth and ENT1 activity by IFN-gamma is required for DNA synthesis. Interestingly, IFN-gamma led to an induction of the CNT1- and CNT2-related nucleoside transport activities independent of STAT1, thus ensuring the supply of extracellular nucleosides for the STAT1-independent RNA synthesis. IFN-gamma up-regulated CNT2 mRNA and CNT1 protein levels and down-regulated ENT1 mRNA in both wild-type and STAT1 knockout macrophages. This is consistent with a STAT1-independent, long-term-mediated, probably transcription-dependent, regulation of nucleoside transporter genes. Moreover, STAT1-dependent post-transcriptional mechanisms are implicated in the regulation of ENT1 activity. Although nitric oxide is involved in the regulation of ENT1 activity in B-cells at a post-transcriptional level, our results show that STAT1-dependent induction of nitric oxide by IFN-gamma is not implicated in the regulation of ENT1 activity in macrophages. Our results indicate that both STAT1-dependent and -independent pathways are involved in the regulation of nucleoside transporters by IFN-gamma in macrophages. PMID:12868960

  1. ROS-dependent signal transduction

    PubMed Central

    Reczek, Colleen R; Chandel, Navdeep S

    2014-01-01

    Reactive oxygen species (ROS) are no longer viewed as just a toxic by-product of mitochondrial respiration, but are now appreciated for their role in regulating a myriad of cellular signaling pathways. H2O2, a type of ROS, is a signaling molecule that confers target specificity through thiol oxidation. Although redox-dependent signaling has been implicated in numerous cellular processes, the mechanism by which the ROS signal is transmitted to its target protein in the face of highly reactive and abundant antioxidants is not fully understood. In this review of redox-signaling biology, we discuss the possible mechanisms for H2O2-dependent signal transduction. PMID:25305438

  2. Meeting Report: Teaching Signal Transduction

    ERIC Educational Resources Information Center

    Kramer, IJsbrand; Thomas, Geraint

    2006-01-01

    In July, 2005, the European Institute of Chemistry and Biology at the campus of the University of Bordeaux, France, hosted a focused week of seminars, workshops, and discussions around the theme of "teaching signal transduction." The purpose of the summer school was to offer both junior and senior university instructors a chance to reflect on the…

  3. Meeting report: Signal transduction meets systems biology

    PubMed Central

    2012-01-01

    In the 21st century, systems-wide analyses of biological processes are getting more and more realistic. Especially for the in depth analysis of signal transduction pathways and networks, various approaches of systems biology are now successfully used. The EU FP7 large integrated project SYBILLA (Systems Biology of T-cell Activation in Health and Disease) coordinates such an endeavor. By using a combination of experimental data sets and computational modelling, the consortium strives for gaining a detailed and mechanistic understanding of signal transduction processes that govern T-cell activation. In order to foster the interaction between systems biologists and experimentally working groups, SYBILLA co-organized the 15th meeting “Signal Transduction: Receptors, Mediators and Genes” together with the Signal Transduction Society (STS). Thus, the annual STS conference, held from November 7 to 9, 2011 in Weimar, Germany, provided an interdisciplinary forum for research on signal transduction with a major focus on systems biology addressing signalling events in T-cells. Here we report on a selection of ongoing projects of SYBILLA and how they were discussed at this interdisciplinary conference. PMID:22546078

  4. Oxidants as stimulators of signal transduction.

    PubMed

    Suzuki, Y J; Forman, H J; Sevanian, A

    1997-01-01

    Redox (oxidation-reduction) reactions regulate signal transduction. Oxidants such as superoxide, hydrogen peroxide, hydroxyl radicals, and lipid hydroperoxides (i.e., reactive oxygen species) are now realized as signaling molecules under subtoxic conditions. Nitric oxide is also an example of a redox mediator. Reactive oxygen species induce various biological processes such as gene expression by stimulating signal transduction components such as Ca(2+)-signaling and protein phosphorylation. Various oxidants increase cytosolic Ca2+; however, the exact origin of Ca2+ is controversial. Ca2+ may be released from the endoplasmic reticulum, extracellular space, or mitochondria in response to oxidant-influence on Ca2+ pumps, channels, and transporters. Alternatively, oxidants may release Ca2+ from Ca2+ binding proteins. Various oxidants stimulate tyrosine as well as serine/threonine phosphorylation, and direct stimulation of protein kinases and inhibition of protein phosphatases by oxidants have been proposed as mechanisms. The oxidant-stimulation of the effector molecules such as phospholipase A2 as well as the activation of oxidative stress-responsive transcription factors may also depend on the oxidant-mediated activation of Ca(2+)-signaling and/or protein phosphorylation. In addition to the stimulation of signal transduction by oxidants, the observations that ligand-receptor interactions produce reactive oxygen species and that antioxidants block receptor-mediated signal transduction led to a proposal that reactive oxygen species may be second messengers for transcription factor activation, apoptosis, bone resorption, cell growth, and chemotaxis. Physiological significance of the role of biological oxidants in the regulation of signal transduction as well as the mechanisms of the oxidant-stimulation of signal transduction are discussed.

  5. Dual signal transduction pathways activated by TSH receptors in rat primary tanycyte cultures.

    PubMed

    Bolborea, Matei; Helfer, Gisela; Ebling, Francis J P; Barrett, Perry

    2015-06-01

    Tanycytes play multiple roles in hypothalamic functions, including sensing peripheral nutrients and metabolic hormones, regulating neurosecretion and mediating seasonal cycles of reproduction and metabolic physiology. This last function reflects the expression of TSH receptors in tanycytes, which detect photoperiod-regulated changes in TSH secretion from the neighbouring pars tuberalis. The present overall aim was to determine the signal transduction pathway by which TSH signals in tanycytes. Expression of the TSH receptor in tanycytes of 10-day-old Sprague Dawley rats was observed by in situ hybridisation. Primary ependymal cell cultures prepared from 10-day-old rats were found by immunohistochemistry to express vimentin but not GFAP and by PCR to express mRNA for Dio2, Gpr50, Darpp-32 and Tsh receptors that are characteristic of tanycytes. Treatment of primary tanycyte/ependymal cultures with TSH (100  IU/l) increased cAMP as assessed by ELISA and induced a cAMP-independent increase in the phosphorylation of ERK1/2 as assessed by western blot analysis. Furthermore, TSH (100  IU/l) stimulated a 2.17-fold increase in Dio2 mRNA expression. We conclude that TSH signal transduction in cultured tanycytes signals via Gαs to increase cAMP and via an alternative G protein to increase phosphorylation of ERK1/2. PMID:25878058

  6. Oxysterols and calcium signal transduction.

    PubMed

    Mackrill, John J

    2011-09-01

    Ionised calcium (Ca(2+)) is a key second messenger, regulating almost every cellular process from cell death to muscle contraction. Cytosolic levels of this ion can be increased via gating of channel proteins located in the plasma membrane, endoplasmic reticulum and other membrane-delimited organelles. Ca(2+) can be removed from cells by extrusion across the plasma membrane, uptake into organelles and buffering by anionic components. Ca(2+) channels and extrusion mechanisms work in concert to generate diverse spatiotemporal patterns of this second messenger, the distinct profiles of which determine different cellular outcomes. Increases in cytoplasmic Ca(2+) concentration are one of the most rapid cellular responses upon exposure to certain oxysterol congeners or to oxidised low-density lipoprotein, occurring within seconds of addition and preceding increases in levels of reactive oxygen species, or changes in gene expression. Furthermore, exposure of cells to oxysterols for periods of hours to days modulates Ca(2+) signal transduction, with these longer-term alterations in cellular Ca(2+) homeostasis potentially underlying pathological events within atherosclerotic lesions, such as hyporeactivity to vasoconstrictors observed in vascular smooth muscle, or ER stress-induced cell death in macrophages. Despite their candidate roles in physiology and disease, little is known about the molecular mechanisms that couple changes in oxysterol concentrations to alterations in Ca(2+) signalling. This review examines the ways in which oxysterols could influence Ca(2+) signal transduction and the potential roles of this in health and disease. PMID:21513705

  7. Signal transduction in T lymphocytes in microgravity

    NASA Technical Reports Server (NTRS)

    Cogoli, A.

    1997-01-01

    More than 120 experiments conducted in space in the last 15 years have shown that dramatic changes are occurring in several types of single cells during their exposure to microgravity. One focus of today's research on cells in space is on signal transduction, especially those steps involving the cytoskeleton and cell-cell interactions. Signal transduction is often altered in microgravity as well as in hypergravity. This leads to changes in cell proliferation, genetic expression and differentiation. Interesting examples are leukocytes, HeLa cells, epidermoid cells and osteoblastic cells. Signalling pathways were studied in T lymphocytes in microgravity by several investigators after the discovery that mitogenic activation in vitro is virtually nil at 0g. T cells are a good model to study signal transduction because three extracellular signals (mitogen, IL-1 and IL-2) are required for full activation, and two classical pathways (via proteins G and PKC) are activated within the cell. In addition, low molecular weight GTP-binding proteins (Ras and Rap) are interacting with the cytoskeleton. The data at 0g support the notion that the expression of IL-2 receptor is inhibited at 0g, while mitogen binding and the transmission of IL-1 by accessory cells occur normally. In addition, alterations of the cytoskeleton suggest that the interaction with Rap proteins is disturbed. Data obtained with phorbol esters indicate that the function of PKC is changed in microgravity. Similar conclusions are drawn from the results with epidermoid cells A431.

  8. Simulated evolution of signal transduction networks.

    PubMed

    Mobashir, Mohammad; Schraven, Burkhart; Beyer, Tilo

    2012-01-01

    Signal transduction is the process of routing information inside cells when receiving stimuli from their environment that modulate the behavior and function. In such biological processes, the receptors, after receiving the corresponding signals, activate a number of biomolecules which eventually transduce the signal to the nucleus. The main objective of our work is to develop a theoretical approach which will help to better understand the behavior of signal transduction networks due to changes in kinetic parameters and network topology. By using an evolutionary algorithm, we designed a mathematical model which performs basic signaling tasks similar to the signaling process of living cells. We use a simple dynamical model of signaling networks of interacting proteins and their complexes. We study the evolution of signaling networks described by mass-action kinetics. The fitness of the networks is determined by the number of signals detected out of a series of signals with varying strength. The mutations include changes in the reaction rate and network topology. We found that stronger interactions and addition of new nodes lead to improved evolved responses. The strength of the signal does not play any role in determining the response type. This model will help to understand the dynamic behavior of the proteins involved in signaling pathways. It will also help to understand the robustness of the kinetics of the output response upon changes in the rate of reactions and the topology of the network.

  9. The Membrane and Lipids as Integral Participants in Signal Transduction: Lipid Signal Transduction for the Non-Lipid Biochemist

    ERIC Educational Resources Information Center

    Eyster, Kathleen M.

    2007-01-01

    Reviews of signal transduction have often focused on the cascades of protein kinases and protein phosphatases and their cytoplasmic substrates that become activated in response to extracellular signals. Lipids, lipid kinases, and lipid phosphatases have not received the same amount of attention as proteins in studies of signal transduction.…

  10. A novel c-Jun-dependent signal transduction pathway necessary for the transcriptional activation of interferon gamma response genes.

    PubMed

    Gough, Daniel J; Sabapathy, Kanaga; Ko, Enoch Yi-No; Arthur, Helen A; Schreiber, Robert D; Trapani, Joseph A; Clarke, Christopher J P; Johnstone, Ricky W

    2007-01-12

    The biological effects of interferon gamma (IFNgamma) are mediated by interferon-stimulated genes (ISGs), many of which are activated downstream of Janus kinase (JAK)/signal transducer and activator of transcription 1 (STAT1) signaling. Herein we have shown that IFNgamma rapidly activated AP-1 DNA binding that required c-Jun but was independent of JAK1 and STAT1. IFNgamma-induced c-Jun phosphorylation and AP-1 DNA binding required the MEK1/2 and ERK1/2 signaling pathways, whereas the JNK1/2 and p38 mitogen-activated protein kinase pathways were dispensable. The induction of several ISGs, including ifi-205 and iNOS, was impaired in IFNgamma-treated c-Jun-/- cells, but others, such as IP-10 and SOCS3, were unaffected, and chromatin immunoprecipitation demonstrated that c-Jun binds to the iNOS promoter following treatment with IFNgamma. Thus, IFNgamma induced JAK1- and STAT1-independent activation of the ERK mitogen-activated protein kinase pathway, phosphorylation of c-Jun, and activation of AP-1 DNA binding, which are important for the induction of a subset of ISGs. This represents a novel signal transduction pathway induced by IFNgamma that proceeds in parallel with conventional JAK/STAT signaling to activate ISGs.

  11. A novel c-Jun-dependent signal transduction pathway necessary for the transcriptional activation of interferon gamma response genes.

    PubMed

    Gough, Daniel J; Sabapathy, Kanaga; Ko, Enoch Yi-No; Arthur, Helen A; Schreiber, Robert D; Trapani, Joseph A; Clarke, Christopher J P; Johnstone, Ricky W

    2007-01-12

    The biological effects of interferon gamma (IFNgamma) are mediated by interferon-stimulated genes (ISGs), many of which are activated downstream of Janus kinase (JAK)/signal transducer and activator of transcription 1 (STAT1) signaling. Herein we have shown that IFNgamma rapidly activated AP-1 DNA binding that required c-Jun but was independent of JAK1 and STAT1. IFNgamma-induced c-Jun phosphorylation and AP-1 DNA binding required the MEK1/2 and ERK1/2 signaling pathways, whereas the JNK1/2 and p38 mitogen-activated protein kinase pathways were dispensable. The induction of several ISGs, including ifi-205 and iNOS, was impaired in IFNgamma-treated c-Jun-/- cells, but others, such as IP-10 and SOCS3, were unaffected, and chromatin immunoprecipitation demonstrated that c-Jun binds to the iNOS promoter following treatment with IFNgamma. Thus, IFNgamma induced JAK1- and STAT1-independent activation of the ERK mitogen-activated protein kinase pathway, phosphorylation of c-Jun, and activation of AP-1 DNA binding, which are important for the induction of a subset of ISGs. This represents a novel signal transduction pathway induced by IFNgamma that proceeds in parallel with conventional JAK/STAT signaling to activate ISGs. PMID:17105733

  12. Angular-type furocoumarins from the roots of Angelica atropurpurea and their inhibitory activity on the NFAT signal transduction pathway.

    PubMed

    Nagasawa, Azumi; Sakasai, Mitsuyoshi; Sakaguchi, Daishi; Moriwaki, Shigeru; Nishizawa, Yoshinori; Kitahara, Takashi

    2014-12-01

    One new (1) and two known angular-type (2,3) furocoumarins, isoarchangelicin (1), archangelicin (2), and 2'-angeloyl-3'-isovaleryl vaginate (3), were isolated from the roots of Angelica atropurpurea. The structure of the new compound was established on the basis of one- and two-dimensional NMR spectra and other spectroscopic studies. The inhibitory activity of these three compounds and a deacylated form of archangelicin (4) on the nuclear factor of activated T cells (NFAT) signal transduction pathway was tested by NFAT-responsive luciferase reporter gene assay in cultured cells. Although 4 did not exhibit inhibitory activity on NFAT signaling, 1-3 exhibited dose-dependent inhibition with IC50 values of 16.5 (1), 9.0 (2), and 9.2 (3) μM.

  13. Gravitational Effects on Signal Transduction

    NASA Technical Reports Server (NTRS)

    Sytkowski, Arthur J.

    1999-01-01

    An understanding of the mechanisms by which individual cells perceive gravity and how these cells transduce and respond to gravitational stimuli is critical for the development of long-term manned space flight experiments. We now propose to use a well-characterized model erythroid cell system and to investigate gravitational perturbations of its erythropoietin (Epo) signaling pathway and gene regulation. Cells will be grown at 1-G and in simulated microgravity in the NASA Rotating Wall Vessel bioreactor (RWV). Cell growth and differentiation, the Epo-receptor, the protein kinase C pathway to the c-myc gene, and the protein phosphatase pathway to the c-myb gene will be studied and evaluated as reporters of gravitational stimuli. The results of these experiments will have impact on the problems of 1) gravitational sensing by individual cells, and 2) the anemia of space flight. This ground-based study also will serve as a Space Station Development Study in gravitational effects on intracellular signal transduction.

  14. Sentra, a database of signal transduction proteins.

    SciTech Connect

    Maltsev, N.; Marland, E.; Yu, G. X.; Bhatnagar, S.; Lusk, R.; Mathematics and Computer Science

    2002-01-01

    Sentra (http://www-wit.mcs.anl.gov/sentra) is a database of signal transduction proteins with the emphasis on microbial signal transduction. The database was updated to include classes of signal transduction systems modulated by either phosphorylation or methylation reactions such as PAS proteins and serine/threonine kinases, as well as the classical two-component histidine kinases and methyl-accepting chemotaxis proteins. Currently, Sentra contains signal transduction proteins from 43 completely sequenced prokaryotic genomes as well as sequences from SWISS-PROT and TrEMBL. Signal transduction proteins are annotated with information describing conserved domains, paralogous and orthologous sequences, and conserved chromosomal gene clusters. The newly developed user interface supports flexible search capabilities and extensive visualization of the data.

  15. SENTRA, a database of signal transduction proteins.

    SciTech Connect

    D'Souza, M.; Romine, M. F.; Maltsev, N.; Mathematics and Computer Science; PNNL

    2000-01-01

    SENTRA, available via URL http://wit.mcs.anl.gov/WIT2/Sentra/, is a database of proteins associated with microbial signal transduction. The database currently includes the classical two-component signal transduction pathway proteins and methyl-accepting chemotaxis proteins, but will be expanded to also include other classes of signal transduction systems that are modulated by phosphorylation or methylation reactions. Although the majority of database entries are from prokaryotic systems, eukaroytic proteins with bacterial-like signal transduction domains are also included. Currently SENTRA contains signal transduction proteins in 34 complete and almost completely sequenced prokaryotic genomes, as well as sequences from 243 organisms available in public databases (SWISS-PROT and EMBL). The analysis was carried out within the framework of the WIT2 system, which is designed and implemented to support genetic sequence analysis and comparative analysis of sequenced genomes.

  16. Helicobacter pylori culture supernatant interferes with epidermal growth factor-activated signal transduction in human gastric KATO III cells.

    PubMed Central

    Pai, R.; Wyle, F. A.; Cover, T. L.; Itani, R. M.; Domek, M. J.; Tarnawski, A. S.

    1998-01-01

    The mechanisms by which Helicobacter pylori infection leads to gastroduodenal ulceration remain poorly understood. Previous studies have shown that H. pylori vacuolating cytotoxin (VacA) inhibits proliferation of gastric epithelial cells, which suggests that H pylori may interfere with gastric mucosal repair mechanisms. In this study, we investigated the effects of H. pylori broth culture supernatants on epidermal growth factor (EGF)-mediated signal transduction pathways in a gastric carcinoma cell line (KATO III). Exposure of these cells to EGF resulted in increased expression and phosphorylation of the EGF receptor (EGF-R), increased ERK2 activity and phosphorylation, and increased c-fos protein levels. Preincubation of cells with broth culture supernatant from VacA (+) H. pylori strain 60190 inhibited the capacity of EGF to induce each of these effects. In contrast, preincubation of cells with broth culture supernatant from an isogenic VacA-mutant strain (H. pylori 60190-v1) failed to inhibit the effects of EGF. These results suggest that the H. pylori vacuolating cytotoxin interferes with EGF-activated signal transduction pathways, which are known to be essential for cell proliferation and ulcer healing. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:9626065

  17. Helicobacter pylori culture supernatant interferes with epidermal growth factor-activated signal transduction in human gastric KATO III cells.

    PubMed

    Pai, R; Wyle, F A; Cover, T L; Itani, R M; Domek, M J; Tarnawski, A S

    1998-06-01

    The mechanisms by which Helicobacter pylori infection leads to gastroduodenal ulceration remain poorly understood. Previous studies have shown that H. pylori vacuolating cytotoxin (VacA) inhibits proliferation of gastric epithelial cells, which suggests that H pylori may interfere with gastric mucosal repair mechanisms. In this study, we investigated the effects of H. pylori broth culture supernatants on epidermal growth factor (EGF)-mediated signal transduction pathways in a gastric carcinoma cell line (KATO III). Exposure of these cells to EGF resulted in increased expression and phosphorylation of the EGF receptor (EGF-R), increased ERK2 activity and phosphorylation, and increased c-fos protein levels. Preincubation of cells with broth culture supernatant from VacA (+) H. pylori strain 60190 inhibited the capacity of EGF to induce each of these effects. In contrast, preincubation of cells with broth culture supernatant from an isogenic VacA-mutant strain (H. pylori 60190-v1) failed to inhibit the effects of EGF. These results suggest that the H. pylori vacuolating cytotoxin interferes with EGF-activated signal transduction pathways, which are known to be essential for cell proliferation and ulcer healing. PMID:9626065

  18. A bead-based activity screen for small-molecule inhibitors of signal transduction in chronic myelogenous leukemia cells

    PubMed Central

    Sylvester, Juliesta E.; Kron, Stephen J.

    2010-01-01

    Chronic myelogenous leukemia is characterized by the presence of the chimeric BCR-ABL gene, which is expressed as the constitutively active Bcr-Abl kinase. Although kinase activity is directly responsible for the clinical phenotype, current diagnostic and prognostic methods focus on a genetic classification system where molecularly distinct subcategories are used to predict patient responses to small-molecule inhibitors of the Bcr-Abl kinase. Point mutations in the kinase domain are a central factor regulating inhibitor resistance; however, compensatory signaling caused by the activation of unrelated kinases can influence inhibitor efficacy. Kinase activity profiling can be used as a complementary approach to genetic screening and allows direct screening of small-molecule inhibitors. We developed a quantitative assay to monitor tyrosine kinase activities and inhibitor sensitivities in a model of chronic myelogenous leukemia using peptide reporters covalently immobilized on Luminex beads. Kinase activity is quantified by non-linear regression from well-specific internal standard curves. Using optimized synthetic substrates and peptides derived from native substrates as probes, we measured kinase inhibition in cell lysates by the signal transduction inhibitors imatinib and dasatinib. Taking advantage of a convenient 96-well plate format, this assay also allows a straightforward and quantitative analysis of the differential effects of ATP and inhibitors on kinase activity. This method for analyzing a focused signaling network benefits from rigorous statistical analysis and short processing times, thereby offering a powerful tool for drug discovery and clinical testing. PMID:20423990

  19. Studying Cellular Signal Transduction with OMIC Technologies

    PubMed Central

    Landry, Benjamin D.; Clarke, David C.; Lee, Michael J.

    2016-01-01

    In the gulf between genotype and phenotype exists proteins and, in particular, protein signal transduction systems. These systems use a relatively limited parts list to respond to a much longer list of extracellular, environmental, and/or mechanical cues with rapidity and specificity. Most signaling networks function in a highly nonlinear and often contextual manner. Furthermore, these processes occur dynamically across space and time. Because of these complexities, systems and “OMIC” approaches are essential for the study of signal transduction. One challenge in using OMIC-scale approaches to study signaling is that the “signal” can take different forms in different situations. Signals are encoded in diverse ways such as protein-protein interactions, enzyme activities, localizations, or post-translational modifications to proteins. Furthermore, in some cases signals may be encoded only in the dynamics, duration, or rates of change of these features. Accordingly, systems-level analyses of signaling may need to integrate multiple experimental and/or computational approaches. As the field has progressed, the non-triviality of integrating experimental and computational analyses has become apparent. Successful use of OMIC methods to study signaling will require the “right” experiments and the “right” modeling approaches, and it is critical to consider both in the design phase of the project. In this review, we discuss common OMIC and modeling approaches for studying signaling, emphasizing the philosophical and practical considerations for effectively merging these two types of approaches to maximize the probability of obtaining reliable and novel insights into signaling biology. PMID:26244521

  20. Identification of signal transduction pathways involved in the formation of platelet subpopulations upon activation.

    PubMed

    Topalov, Nikolai N; Kotova, Yana N; Vasil'ev, Sergey A; Panteleev, Mikhail A

    2012-04-01

    Platelets are formed elements of blood. Upon activation, they externalize phosphatidylserine, thus accelerating membrane-dependent reactions of blood coagulation. Activated platelets form two subpopulations, only one of which expresses phosphatidylserine. This study aimed to identify signalling pathways responsible for this segregation. Gel-filtered platelets, intact or loaded with calcium-sensitive dyes, were activated and labelled with annexin V and antibodies, followed by flow cytometric analysis. Calcium Green and Fura Red dyes were compared, and only the latter was able to detect calcium level differences in the platelet subpopulations. Phosphatidylserine-positive platelets produced by thrombin had stably high intracellular calcium level; addition of convulxin increased and stabilized calcium level in the phosphatidylserine-negative subpopulation. PAR1 agonist SFLLRN also induced calcium rise and subpopulation formation, but the resulting platelets were not coated with alpha-granule proteins. Adenylatecyclase activator forskolin inhibited phosphatidylserine-positive platelets formation several-fold, while its inhibitor SQ22536 had no effect. This suggests that adenylatecyclase inactivation is necessary, but not rate-limiting, for subpopulation segregation. Inhibition of mitogen-activated protein kinase kinase (U0126) and glycoprotein IIb-IIIa (Monafram(®)) was without effect, whereas inhibitors of phosphatidylinositol 3-kinase (wortmannin) and Src tyrosine kinase (PP2) decreased the procoagulant subpopulation threefold. These data identify the principal signalling pathways controlling platelet heterogeneity. PMID:23379894

  1. Calcium and signal transduction in plants

    NASA Technical Reports Server (NTRS)

    Poovaiah, B. W.; Reddy, A. S.

    1993-01-01

    Environmental and hormonal signals control diverse physiological processes in plants. The mechanisms by which plant cells perceive and transduce these signals are poorly understood. Understanding biochemical and molecular events involved in signal transduction pathways has become one of the most active areas of plant research. Research during the last 15 years has established that Ca2+ acts as a messenger in transducing external signals. The evidence in support of Ca2+ as a messenger is unequivocal and fulfills all the requirements of a messenger. The role of Ca2+ becomes even more important because it is the only messenger known so far in plants. Since our last review on the Ca2+ messenger system in 1987, there has been tremendous progress in elucidating various aspects of Ca(2+) -signaling pathways in plants. These include demonstration of signal-induced changes in cytosolic Ca2+, calmodulin and calmodulin-like proteins, identification of different Ca2+ channels, characterization of Ca(2+) -dependent protein kinases (CDPKs) both at the biochemical and molecular levels, evidence for the presence of calmodulin-dependent protein kinases, and increased evidence in support of the role of inositol phospholipids in the Ca(2+) -signaling system. Despite the progress in Ca2+ research in plants, it is still in its infancy and much more needs to be done to understand the precise mechanisms by which Ca2+ regulates a wide variety of physiological processes. The purpose of this review is to summarize some of these recent developments in Ca2+ research as it relates to signal transduction in plants.

  2. Biological Activities of Reactive Oxygen and Nitrogen Species: Oxidative Stress versus Signal Transduction.

    PubMed

    Weidinger, Adelheid; Kozlov, Andrey V

    2015-01-01

    In the past, reactive oxygen and nitrogen species (RONS) were shown to cause oxidative damage to biomolecules, contributing to the development of a variety of diseases. However, recent evidence has suggested that intracellular RONS are an important component of intracellular signaling cascades. The aim of this review was to consolidate old and new ideas on the chemical, physiological and pathological role of RONS for a better understanding of their properties and specific activities. Critical consideration of the literature reveals that deleterious effects do not appear if only one primary species (superoxide radical, nitric oxide) is present in a biological system, even at high concentrations. The prerequisite of deleterious effects is the formation of highly reactive secondary species (hydroxyl radical, peroxynitrite), emerging exclusively upon reaction with another primary species or a transition metal. The secondary species are toxic, not well controlled, causing irreversible damage to all classes of biomolecules. In contrast, primary RONS are well controlled (superoxide dismutase, catalase), and their reactions with biomolecules are reversible, making them ideal for physiological/pathophysiological intracellular signaling. We assume that whether RONS have a signal transducing or damaging effect is primarily defined by their quality, being primary or secondary RONS, and only secondly by their quantity. PMID:25884116

  3. Biological Activities of Reactive Oxygen and Nitrogen Species: Oxidative Stress versus Signal Transduction

    PubMed Central

    Weidinger, Adelheid; Kozlov, Andrey V.

    2015-01-01

    In the past, reactive oxygen and nitrogen species (RONS) were shown to cause oxidative damage to biomolecules, contributing to the development of a variety of diseases. However, recent evidence has suggested that intracellular RONS are an important component of intracellular signaling cascades. The aim of this review was to consolidate old and new ideas on the chemical, physiological and pathological role of RONS for a better understanding of their properties and specific activities. Critical consideration of the literature reveals that deleterious effects do not appear if only one primary species (superoxide radical, nitric oxide) is present in a biological system, even at high concentrations. The prerequisite of deleterious effects is the formation of highly reactive secondary species (hydroxyl radical, peroxynitrite), emerging exclusively upon reaction with another primary species or a transition metal. The secondary species are toxic, not well controlled, causing irreversible damage to all classes of biomolecules. In contrast, primary RONS are well controlled (superoxide dismutase, catalase), and their reactions with biomolecules are reversible, making them ideal for physiological/pathophysiological intracellular signaling. We assume that whether RONS have a signal transducing or damaging effect is primarily defined by their quality, being primary or secondary RONS, and only secondly by their quantity. PMID:25884116

  4. Inquiry into chemotherapy-induced p53 activation in cancer cells as a model for teaching signal transduction.

    PubMed

    Srougi, Melissa C; Carson, Susan

    2013-01-01

    Intracellular and extracellular communication is conducted through an intricate and interwoven network of signal transduction pathways. The mechanisms for how cells speak with one another are of significant biological importance to both basic and industrial scientists from a number of different disciplines. We have therefore developed and implemented a new laboratory-intensive course that teaches students the theory and techniques used to study cell signaling pathways. Students learn these methodologies as they conduct a hypothesis-driven research project where they elucidate the mechanism of breast cancer cell death caused by a cancer chemotherapeutic agent. While each lab experiment can be conducted independently, the findings build upon one another to form the beginnings of a signaling pathway. In the lecture component of the course, students investigate different signaling pathways and the methods employed to study them. In addition, students actively participate in journal article discussions where they assess the primary scientific literature. We evaluated the course over two semesters and found that in both semesters learning outcomes were met by both undergraduate and graduate students. The evaluation of the course was based on a number of instructor assessments of student work, including lab reports, experimental results, journal article discussions, and a final cumulative exam. Furthermore, students' self-assessments revealed gains in perceived confidence in both conceptual knowledge and technical skills

  5. Inquiry into chemotherapy-induced p53 activation in cancer cells as a model for teaching signal transduction.

    PubMed

    Srougi, Melissa C; Carson, Susan

    2013-01-01

    Intracellular and extracellular communication is conducted through an intricate and interwoven network of signal transduction pathways. The mechanisms for how cells speak with one another are of significant biological importance to both basic and industrial scientists from a number of different disciplines. We have therefore developed and implemented a new laboratory-intensive course that teaches students the theory and techniques used to study cell signaling pathways. Students learn these methodologies as they conduct a hypothesis-driven research project where they elucidate the mechanism of breast cancer cell death caused by a cancer chemotherapeutic agent. While each lab experiment can be conducted independently, the findings build upon one another to form the beginnings of a signaling pathway. In the lecture component of the course, students investigate different signaling pathways and the methods employed to study them. In addition, students actively participate in journal article discussions where they assess the primary scientific literature. We evaluated the course over two semesters and found that in both semesters learning outcomes were met by both undergraduate and graduate students. The evaluation of the course was based on a number of instructor assessments of student work, including lab reports, experimental results, journal article discussions, and a final cumulative exam. Furthermore, students' self-assessments revealed gains in perceived confidence in both conceptual knowledge and technical skills PMID:24259336

  6. Activation of α2A-adrenergic signal transduction in chondrocytes promotes degenerative remodelling of temporomandibular joint

    PubMed Central

    Jiao, Kai; Zeng, Guang; Niu, Li-Na; Yang, Hong-xu; Ren, Gao-tong; Xu, Xin-yue; Li, Fei-fei; Tay, Franklin R.; Wang, Mei-qing

    2016-01-01

    This study tested whether activation of adrenoreceptors in chondrocytes has roles in degenerative remodelling of temporomandibular joint (TMJ) and to determine associated mechanisms. Unilateral anterior crossbite (UAC) was established to induce TMJ degeneration in rats. Saline vehicle, α2- and β-adrenoreceptor antagonists or agonists were injected locally into the TMJ area of UAC rats. Cartilage degeneration, subchondral bone microarchitecture and the expression of adrenoreceptors, aggrecans, matrix metalloproteinases (MMPs) and RANKL by chondrocytes were evaluated. Chondrocytes were stimulated by norepinephrine to investigate signal transduction of adrenoreceptors. Increased α2A-adrenoreceptor expression was observed in condylar cartilage of UAC rats, together with cartilage degeneration and subchondral bone loss. Norepinephrine depresses aggrecans expression but stimulates MMP-3, MMP-13 and RANKL production by chondrocytes through ERK1/2 and PKA pathway; these effects were abolished by an α2A-adrenoreceptor antagonist. Furthermore, inhibition of α2A-adrenoreceptor attenuated degenerative remodelling in the condylar cartilage and subchondral bone, as revealed by increased cartilage thickness, proteoglycans and aggrecan expression, and decreased MMP-3, MMP-13 and RANKL expressions in cartilage, increased BMD, BV/TV, and decreased Tb.Sp in subchondral bone. Conversely, activation of α2A-adrenoreceptor intensified aforementioned degenerative changes in UAC rats. It is concluded that activation of α2A-adrenergic signal in chondrocytes promotes TMJ degenerative remodelling by chondrocyte-mediated pro-catabolic activities. PMID:27452863

  7. Activation of α2A-adrenergic signal transduction in chondrocytes promotes degenerative remodelling of temporomandibular joint.

    PubMed

    Jiao, Kai; Zeng, Guang; Niu, Li-Na; Yang, Hong-Xu; Ren, Gao-Tong; Xu, Xin-Yue; Li, Fei-Fei; Tay, Franklin R; Wang, Mei-Qing

    2016-07-25

    This study tested whether activation of adrenoreceptors in chondrocytes has roles in degenerative remodelling of temporomandibular joint (TMJ) and to determine associated mechanisms. Unilateral anterior crossbite (UAC) was established to induce TMJ degeneration in rats. Saline vehicle, α2- and β-adrenoreceptor antagonists or agonists were injected locally into the TMJ area of UAC rats. Cartilage degeneration, subchondral bone microarchitecture and the expression of adrenoreceptors, aggrecans, matrix metalloproteinases (MMPs) and RANKL by chondrocytes were evaluated. Chondrocytes were stimulated by norepinephrine to investigate signal transduction of adrenoreceptors. Increased α2A-adrenoreceptor expression was observed in condylar cartilage of UAC rats, together with cartilage degeneration and subchondral bone loss. Norepinephrine depresses aggrecans expression but stimulates MMP-3, MMP-13 and RANKL production by chondrocytes through ERK1/2 and PKA pathway; these effects were abolished by an α2A-adrenoreceptor antagonist. Furthermore, inhibition of α2A-adrenoreceptor attenuated degenerative remodelling in the condylar cartilage and subchondral bone, as revealed by increased cartilage thickness, proteoglycans and aggrecan expression, and decreased MMP-3, MMP-13 and RANKL expressions in cartilage, increased BMD, BV/TV, and decreased Tb.Sp in subchondral bone. Conversely, activation of α2A-adrenoreceptor intensified aforementioned degenerative changes in UAC rats. It is concluded that activation of α2A-adrenergic signal in chondrocytes promotes TMJ degenerative remodelling by chondrocyte-mediated pro-catabolic activities.

  8. Activation of α2A-adrenergic signal transduction in chondrocytes promotes degenerative remodelling of temporomandibular joint.

    PubMed

    Jiao, Kai; Zeng, Guang; Niu, Li-Na; Yang, Hong-Xu; Ren, Gao-Tong; Xu, Xin-Yue; Li, Fei-Fei; Tay, Franklin R; Wang, Mei-Qing

    2016-01-01

    This study tested whether activation of adrenoreceptors in chondrocytes has roles in degenerative remodelling of temporomandibular joint (TMJ) and to determine associated mechanisms. Unilateral anterior crossbite (UAC) was established to induce TMJ degeneration in rats. Saline vehicle, α2- and β-adrenoreceptor antagonists or agonists were injected locally into the TMJ area of UAC rats. Cartilage degeneration, subchondral bone microarchitecture and the expression of adrenoreceptors, aggrecans, matrix metalloproteinases (MMPs) and RANKL by chondrocytes were evaluated. Chondrocytes were stimulated by norepinephrine to investigate signal transduction of adrenoreceptors. Increased α2A-adrenoreceptor expression was observed in condylar cartilage of UAC rats, together with cartilage degeneration and subchondral bone loss. Norepinephrine depresses aggrecans expression but stimulates MMP-3, MMP-13 and RANKL production by chondrocytes through ERK1/2 and PKA pathway; these effects were abolished by an α2A-adrenoreceptor antagonist. Furthermore, inhibition of α2A-adrenoreceptor attenuated degenerative remodelling in the condylar cartilage and subchondral bone, as revealed by increased cartilage thickness, proteoglycans and aggrecan expression, and decreased MMP-3, MMP-13 and RANKL expressions in cartilage, increased BMD, BV/TV, and decreased Tb.Sp in subchondral bone. Conversely, activation of α2A-adrenoreceptor intensified aforementioned degenerative changes in UAC rats. It is concluded that activation of α2A-adrenergic signal in chondrocytes promotes TMJ degenerative remodelling by chondrocyte-mediated pro-catabolic activities. PMID:27452863

  9. Inquiry into Chemotherapy-Induced P53 Activation in Cancer Cells as a Model for Teaching Signal Transduction

    ERIC Educational Resources Information Center

    Srougi, Melissa C.; Carson, Susan

    2013-01-01

    Intracellular and extracellular communication is conducted through an intricate and interwoven network of signal transduction pathways. The mechanisms for how cells speak with one another are of significant biological importance to both basic and industrial scientists from a number of different disciplines. We have therefore developed and…

  10. Engineering key components in a synthetic eukaryotic signal transduction pathway

    PubMed Central

    Antunes, Mauricio S; Morey, Kevin J; Tewari-Singh, Neera; Bowen, Tessa A; Smith, J Jeff; Webb, Colleen T; Hellinga, Homme W; Medford, June I

    2009-01-01

    Signal transduction underlies how living organisms detect and respond to stimuli. A goal of synthetic biology is to rewire natural signal transduction systems. Bacteria, yeast, and plants sense environmental aspects through conserved histidine kinase (HK) signal transduction systems. HK protein components are typically comprised of multiple, relatively modular, and conserved domains. Phosphate transfer between these components may exhibit considerable cross talk between the otherwise apparently linear pathways, thereby establishing networks that integrate multiple signals. We show that sequence conservation and cross talk can extend across kingdoms and can be exploited to produce a synthetic plant signal transduction system. In response to HK cross talk, heterologously expressed bacterial response regulators, PhoB and OmpR, translocate to the nucleus on HK activation. Using this discovery, combined with modification of PhoB (PhoB-VP64), we produced a key component of a eukaryotic synthetic signal transduction pathway. In response to exogenous cytokinin, PhoB-VP64 translocates to the nucleus, binds a synthetic PlantPho promoter, and activates gene expression. These results show that conserved-signaling components can be used across kingdoms and adapted to produce synthetic eukaryotic signal transduction pathways. PMID:19455134

  11. MKK3- and MKK6-regulated gene expression is mediated by the p38 mitogen-activated protein kinase signal transduction pathway.

    PubMed Central

    Raingeaud, J; Whitmarsh, A J; Barrett, T; Dérijard, B; Davis, R J

    1996-01-01

    The p38 mitogen-activated protein (MAP) kinase signal transduction pathway is activated by proinflammatory cytokines and environmental stress. The detection of p38 MAP kinase in the nucleus of activated cells suggests that p38 MAP kinase can mediate signaling to the nucleus. To test this hypothesis, we constructed expression vectors for activated MKK3 and MKK6, two MAP kinase kinases that phosphorylate and activate p38 MAP kinase. Expression of activated MKK3 and MKK6 in cultured cells caused a selective increase in p38 MAP kinase activity. Cotransfection experiments demonstrated that p38 MAP kinase activation causes increased reporter gene expression mediated by the transcription factors ATF2 and Elk-1. These data demonstrate that the nucleus is one target of the p38 MAP kinase signal transduction pathway. PMID:8622669

  12. Phosphoproteomic analysis of induced resistance reveals activation of signal transduction processes by beneficial and pathogenic interaction in grapevine.

    PubMed

    Perazzolli, Michele; Palmieri, Maria Cristina; Matafora, Vittoria; Bachi, Angela; Pertot, Ilaria

    2016-05-20

    Protein phosphorylation regulates several key processes of the plant immune system. Protein kinases and phosphatases are pivotal regulators of defense mechanisms elicited by resistance inducers. However, the phosphorylation cascades that trigger the induced resistance mechanisms in plants have not yet been deeply investigated. The beneficial fungus Trichoderma harzianum T39 (T39) induces resistance against grapevine downy mildew (Plasmopara viticola), but its efficacy could be further improved by a better understanding of the cellular regulations involved. We investigated quantitative changes in the grapevine phosphoproteome during T39-induced resistance to get an overview of regulatory mechanisms of downy mildew resistance. Immunodetection experiments revealed activation of the 45 and 49kDa kinases by T39 treatment both before and after pathogen inoculation, and the phosphoproteomic analysis identified 103 phosphopeptides that were significantly affected by the phosphorylation cascades during T39-induced resistance. Peptides affected by T39 treatment showed comparable phosphorylation levels after P. viticola inoculation, indicating activation of the microbial recognition machinery before pathogen infection. Phosphorylation profiles of proteins related to photosynthetic processes and protein ubiquitination indicated a partial overlap of cellular responses in T39-treated and control plants. However, phosphorylation changes of proteins involved in response to stimuli, signal transduction, hormone signaling, gene expression regulation, and RNA metabolism were exclusively elicited by P. viticola inoculation in T39-treated plants. These results highlighted the relevance of phosphorylation changes during T39-induced resistance and identified key regulator candidates of the grapevine defense against downy mildew. PMID:27010348

  13. Sperm-activating peptides in the regulation of ion fluxes, signal transduction and motility.

    PubMed

    Darszon, Alberto; Guerrero, Adán; Galindo, Blanca E; Nishigaki, Takuya; Wood, Christopher D

    2008-01-01

    Echinoderm sperm use cyclic nucleotides (CNs) as essential second messengers to locate and swim towards the egg. Sea urchin sperm constitute a rich source of membrane-bound guanylyl cyclase (mGC), which was first cloned from sea urchin testis by the group of David Garbers. His group also identified speract, the first sperm-activating peptide (SAP) to be isolated from the egg investment (or egg jelly). This decapeptide stimulates sperm mGC causing a fast transient increase in cGMP that triggers an orchestrated set of physiological responses including: changes in: membrane potential, intracellular pH (pHi), intracellular Ca2+ concentration ([Ca2+]i) and cAMP levels. Evidence from several groups indicated that cGMP activation of a K+ selective channel was the first ion permeability change in the signaling cascade induced by SAPs, and recently the candidate gene was finally identified. Each of the 4 repeated, 6 trans-membrane segments of this channel contains a cyclic nucleotide binding domain. Together they comprise a single polypeptide chain like voltage-gated Na+ or Ca2+ channels. This new type of channel, named tetraKCNG, appears to belong to the exclusive club of novel protein families expressed only in sperm and its progenitors. SAPs also induce fluctuations in flagellar [Ca2+]i that correlate with changes in flagellar form and regulate sperm trajectory. The motility changes depend on [Ca2+]i influx through specific Ca2+ channels and not on the overall [Ca2+]i in the sperm flagellum. All cilia and flagella have a conserved axonemal structure and thus understanding how Ca2+ regulates cilia and flagella beating is a fundamental question. PMID:18649273

  14. Modeling Signal Transduction and Lipid Rafts in Immune Cells

    NASA Astrophysics Data System (ADS)

    Prasad, Ashok

    2011-03-01

    Experimental evidence increasingly suggests that lipid rafts are nanometer sized cholesterol dependent dynamic assemblies enriched in sphingolipids and associated proteins. Lipid rafts are dynamic structures that break-up and reform on a relatively short time-scale, and are believed to facilitate the interactions of raft-associated proteins. The role of these rafts in signaling has been controversial, partly due to controversies regarding the existence and nature of the rafts themselves. Experimental evidence has indicated that in several cell types, especially T cells, rafts do influence signal transduction and T cell activation. Given the emerging consensus on the biophysical character of lipid rafts, the question can be asked as to what roles they possibly play in signal transduction. Here we carry out simulations of minimal models of the signal transduction network that regulates Src-family kinase dynamics in T cells and other cell types. By separately treating raft-based biochemical interactions, we find that rafts can indeed putatively play an important role in signal transduction, and in particular may affect the sensitivity of signal transduction. This illuminates possible functional consequences of membrane heterogeneities on signal transduction and points towards mechanisms for spatial control of signaling by cells.

  15. Glycosphingolipid–Protein Interaction in Signal Transduction

    PubMed Central

    Russo, Domenico; Parashuraman, Seetharaman; D’Angelo, Giovanni

    2016-01-01

    Glycosphingolipids (GSLs) are a class of ceramide-based glycolipids essential for embryo development in mammals. The synthesis of specific GSLs depends on the expression of distinctive sets of GSL synthesizing enzymes that is tightly regulated during development. Several reports have described how cell surface receptors can be kept in a resting state or activate alternative signalling events as a consequence of their interaction with GSLs. Specific GSLs, indeed, interface with specific protein domains that are found in signalling molecules and which act as GSL sensors to modify signalling responses. The regulation exerted by GSLs on signal transduction is orthogonal to the ligand–receptor axis, as it usually does not directly interfere with the ligand binding to receptors. Due to their properties of adjustable production and orthogonal action on receptors, GSLs add a new dimension to the control of the signalling in development. GSLs can, indeed, dynamically influence progenitor cell response to morphogenetic stimuli, resulting in alternative differentiation fates. Here, we review the available literature on GSL–protein interactions and their effects on cell signalling and development. PMID:27754465

  16. Photochemical Modulation of Ras-Mediated Signal Transduction using Caged Farnesyltransferase Inhibitors: Activation via One- and Two-Photon Excitation

    PubMed Central

    Abate-Pella, Daniel; Zeliadt, Nicholette A.; Ochocki, Joshua D.; Warmka, Janel K.; Dore, Timothy M.; Blank, David A.; Wattenberg, Elizabeth V.; Distefano, Mark D.

    2012-01-01

    The creation of caged molecules involves the attachment of protecting groups to biologically active compounds such as ligands, substrates, and drugs that can be removed under specific conditions. Photoremovable caging groups are the most common due to their ability to be removed with high spatial and temporal resolution. Here, the synthesis and photochemistry of a caged inhibitor of protein farnesyltransferase, Bhc-FTI, is described. The inhibitor was caged by alkylation of a critical thiol functional group with a Bhc moiety; while Bhc is well established as a protecting group for carboxylates and phosphates, it has not been extensively used to cage sulfhydryls. The resulting caged molecule, Bhc-FTI, can be photolyzed with UV light to release the inhibitor (FTI) that prevents Ras farnesylation, Ras membrane localization and downstream signaling. Finally, it is shown that Bhc-FTI can be uncaged by two-photon excitation to produce FTI at levels sufficient to inhibit Ras localization and alter cell morphology. Given the widespread involvement of Ras proteins in signal transduction pathways, this caged inhibitor should be useful in a plethora of studies. PMID:22492666

  17. The Hedgehog Signal Transduction Network

    PubMed Central

    Robbins, David J.; Fei, Dennis Liang; Riobo, Natalia A.

    2013-01-01

    Hedgehog (Hh) proteins regulate the development of a wide range of metazoan embryonic and adult structures, and disruption of Hh signaling pathways results in various human diseases. Here, we provide a comprehensive review of the signaling pathways regulated by Hh, consolidating data from a diverse array of organisms in a variety of scientific disciplines. Similar to the elucidation of many other signaling pathways, our knowledge of Hh signaling developed in a sequential manner centered on its earliest discoveries. Thus, our knowledge of Hh signaling has for the most part focused on elucidating the mechanism by which Hh regulates the Gli family of transcription factors, the so-called “canonical” Hh signaling pathway. However, in the past few years, numerous studies have shown that Hh proteins can also signal through Gli-independent mechanisms collectively referred to as “noncanonical” signaling pathways. Noncanonical Hh signaling is itself subdivided into two distinct signaling modules: (i) those not requiring Smoothened (Smo) and (ii) those downstream of Smo that do not require Gli transcription factors. Thus, Hh signaling is now proposed to occur through a variety of distinct context-dependent signaling modules that have the ability to crosstalk with one another to form an interacting, dynamic Hh signaling network. PMID:23074268

  18. Hydrogen Peroxide–Mediated Activation of MAP Kinase 6 Modulates Nitric Oxide Biosynthesis and Signal Transduction in Arabidopsis[w

    PubMed Central

    Wang, Pengcheng; Du, Yanyan; Li, Yuan; Ren, Dongtao; Song, Chun-Peng

    2010-01-01

    Nitric oxide (NO) is a bioactive molecule that functions in numerous physiological and developmental processes in plants, including lateral root development. In this study, we used biochemical and genetic approaches to analyze the function of Arabidopsis thaliana mitogen-activated protein kinase 6 (MPK6) in the regulation of NO synthesis in response to hydrogen peroxide (H2O2) during lateral root development. In both mpk6 mutants studied, H2O2-induced NO synthesis and nitrate reductase (NR) activity were decreased dramatically. Furthermore, one NR isoform, NIA2, was required for the MPK6-mediated production of NO induced by H2O2. Notably, NIA2 interacted physically with MPK6 in vitro and in vivo and also served as a substrate of MPK6. Phosphorylation of NIA2 by MPK6 led to an increase in NR activity, and Ser-627 was identified as the putative phosphorylation site on NIA2. Phenotypical analysis revealed that mpk6-2 and mpk6-3 seedlings produce more and longer lateral roots than wild-type plants did after application of the NO donor sodium nitroprusside or H2O2. These data support strongly a function of MPK6 in modulating NO production and signal transduction in response to H2O2 during Arabidopsis root development. PMID:20870959

  19. Green Light to Illuminate Signal Transduction Events

    PubMed Central

    Balla, Tamas

    2009-01-01

    When cells are exposed to hormones that act on cell surface receptors, information is processed through the plasma membrane into the cell interior via second messengers generated in the inner leaflet of the plasma membrane. Individual biochemical steps along this cascade, starting with ligand binding to receptors to activation of guanine nucleotide binding proteins and their downstream effectors such as adenylate cyclase or phospholipase C, have been biochemically characterized. However, the complexity of temporal and spatial integration of these molecular events requires that they be studied in intact cells. The great expansion of fluorescent techniques and improved imaging technologies such as confocal- and TIRF microscopy combined with genetically engineered protein modules has provided a completely new approach to signal transduction research. Spatial definition of biochemical events followed with real-time temporal resolution has become a standard goal and we are breaking the resolution barrier of light microscopes with several new techniques. PMID:19818623

  20. Signal transduction mechanisms in plants: an overview

    NASA Technical Reports Server (NTRS)

    Clark, G. B.; Thompson, G. Jr; Roux, S. J.

    2001-01-01

    This article provides an overview on recent advances in some of the basic signalling mechanisms that participate in a wide variety of stimulus-response pathways. The mechanisms include calcium-based signalling, G-protein-mediated-signalling and signalling involving inositol phospholipids, with discussion on the role of protein kinases and phosphatases interspersed. As a further defining feature, the article highlights recent exciting findings on three extracellular components that have not been given coverage in previous reviews of signal transduction in plants, extracellular calmodulin, extracellular ATP, and integrin-like receptors, all of which affect plant growth and development.

  1. MOLECULAR MECHANISMS OF RECEPTOR KINASE ACTION IN BRASSINOSTEROID SIGNAL TRANSDUCTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Brassinosteroids (BRs) regulate multiple aspects of plant growth and development and require an active BRASSINOSTEROID INSENSITIVE 1 (BRI1) and BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1) for hormone perception and signal transduction. To examine early events in BR signaling, we used co-immunoprecipita...

  2. A cytoplasmic activator of DNA replication is involved in signal transduction in antigen-specific T cell lines.

    PubMed

    Wong, R L; Clark, R B; Gutowski, J K; Katz, M E; Fresa, K L; Cohen, S

    1990-05-01

    Cytoplasmic extracts prepared from T cell lines undergoing antigen-specific, interleukin-2 (IL-2)-dependent proliferation were tested for their ability to induce DNA synthesis in isolated, quiescent nuclei. A tetanus toxoid (TET)-specific T cell line, established from peripheral blood of a normal human volunteer, was stimulated in the presence of relevant antigen and 1 unit/ml IL-2. Cytoplasmic extracts prepared from these cells were capable of inducing DNA synthesis in isolated, quiescent nuclei. The ability of cytoplasmic extracts to induce DNA synthesis in isolated, quiescent nuclei. The ability of cytoplasmic extracts to induce DNA synthesis in isolated nuclei correlated positively with the degree of proliferation induced in these cells. In contrast, incubation of this T cell line in the absence of antigen failed to induce proliferation and cytoplasmic extracts prepared from these cells induced little to no DNA synthesis in isolated, quiescent nuclei. The factor present in the cytoplasm of T cells stimulated with relevant antigen in the presence of IL-2 is similar, if not identical, to a factor which we have previously demonstrated in cytoplasmic extracts prepared from transformed lymphoblastoid cell lines and from mitogenically stimulated normal human peripheral blood mononuclear cells. This factor, which we have called activator of DNA replication (ADR) is a heat-labile protein, and is inactivated by treatment with protease inhibitors, including aprotinin. The ability of cytoplasmic extracts from T cells undergoing antigen-specific, IL-2-dependent proliferation to induce DNA synthesis in isolated, quiescent nuclei was markedly inhibited in the presence of aprotinin, providing strong evidence that a cytoplasmic activator of DNA replication, ADR, is involved in the signal transduction process for antigen-specific, IL-2-dependent T cell proliferation. ADR may represent a common intracellular mediator of DNA synthesis in activated and transformed lymphocytes

  3. A triterpene saponin from Tribulus terrestris attenuates apoptosis in cardiocyte via activating PKC signalling transduction pathway.

    PubMed

    Sun, Wei; Li, Hong; Yang, Shi-Jie

    2008-01-01

    The present study was conducted to examine the role of hecogenin-3-O-beta-D-glucopyranosyl(1-->4)-beta-D-galactopyranoside (1), which is a triterpene saponin of Tribulus terrestris in cardiocytes during chemical hypoxia-ischaemia in vitro. Neonatal rat ventricular myocytes were isolated by collagenase digestion and treated with NaCN for 12 h. Cell apoptosis was defined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) and flow cytometry. [Ca(2+)] was measured by confocal microscopy. There was a marked increase in the expression of the anti-apoptotic protein, Bcl-2, by NaCN. This change was increased by the saponin 1. PKCepsilon protein contents were increased in the cardiocyte membrane fraction in response to NaCN. PKCepsilon activation was augmented by the saponin 1. Inhibition of PKCepsilon with inhibitory peptide prevented Bcl-2 expression. Moreover, the saponin attenuated the apoptosis in cardiocyte in response to NaCN. It is therefore suggested that the saponin 1 may play a role in cardiocyte survival via PKCepsilon and Bcl-2.

  4. The ethylene signal transduction pathway in Arabidopsis

    NASA Technical Reports Server (NTRS)

    Kieber, J. J.; Evans, M. L. (Principal Investigator)

    1997-01-01

    The gaseous hormone ethylene is an important regulator of plant growth and development. Using a simple response of etiolated seedlings to ethylene as a genetic screen, genes involved in ethylene signal transduction have been identified in Arabidopsis. Analysis of two of these genes that have been cloned reveals that ethylene signalling involves a combination of a protein (ETR1) with similarity to bacterial histidine kinases and a protein (CTR1) with similarity to Raf-1, a protein kinase involved in multiple signalling cascades in eukaryotic cells. Several lines of investigation provide compelling evidence that ETR1 encodes an ethylene receptor. For the first time there is a glimpse of the molecular circuitry underlying the signal transduction pathway for a plant hormone.

  5. Effect of propranolol on platelet signal transduction.

    PubMed Central

    Dash, D; Rao, K

    1995-01-01

    Propranolol inhibits platelet secondary aggregation and secretion by mechanisms unrelated to its beta-adrenergic-blocking activity. We previously reported that a major effect of the drug is perturbation of the physical microenvironment of the human platelet membrane. To explore further the molecular mechanisms underlying propranolol-mediated platelet inhibition, we studied protein kinase C activity, estimated from the phosphorylation of the substrate protein pleckstrin, in propranolol-treated human platelets. The drug inhibited activation of the enzyme in thrombin-stimulated platelets but not in platelets stimulated with phorbol esters, indicating that its site of action might be upstream of protein kinase C. It also inhibited the activity of phospholipase C, determined from the extent of generation of inositol phosphates and phosphatidic acid, in platelets stimulated with thrombin as well as the non-hydrolysable GTP analogue guanosine 5'-[beta, gamma-imido]triphosphate in a dose-dependent manner. These data suggest that propranolol inhibits signal transduction in thrombin-stimulated platelets by interacting at the level of phospholipase C and exclude interaction of the drug with the downstream effector enzyme protein kinase C. Images Figure 1 Figure 2 Figure 3 PMID:7619088

  6. Gravitational Effects on Signal Transduction

    NASA Technical Reports Server (NTRS)

    Sytkowski, Arthur J.

    1999-01-01

    The purpose of this study was to investigate in ground-based experiments, the effect of microgravity on in vitro erythroid differentiation triggered by the hematopoietic growth factor erythropoietin (Epo) and to begin to determine whether this is associated with the anemia of space flight. We chose to use a model cell culture system with which we have had a long and successful experience. These cells, designated Rauscher murine erythroleukemia, grow independently in suspension culture. We first compared the growth rate of Rauscher cells under conditions of simulated microgravity with that of cells grown at 1XG in standard tissue culture flasks. Therefore, since there were fewer cells in the RWV at each specified time, glucose consumption per cell was increased in simulated microgravity. We next began to study the effect of simulated microgravity on erythropoietin induced differentiation of these cells. In another experiment, we allow the cells to grown in flasks or in the RWV for 24 hours prior to the addition of Epo. We initiated studies of c-myb, a proto-oncogene the down-regulation of which is necessary for erythroid differentiation. These preliminary results suggest that simulated microgravity interferes with the signal to c-myb. This may be part of the mechanism that blocks differentiation. A flight experiment is planned within the next 18- 24 months.

  7. Advances in Targeting Signal Transduction Pathways

    PubMed Central

    McCubrey, James A.; Steelman, Linda S.; Chappell, William H.; Sun, Lin; Davis, Nicole M.; Abrams, Stephen L.; Franklin, Richard A.; Cocco, Lucio; Evangelisti, Camilla; Chiarini, Francesca; Martelli, Alberto M.; Libra, Massimo; Candido, Saverio; Ligresti, Giovanni; Malaponte, Grazia; Mazzarino, Maria C.; Fagone, Paolo; Donia, Marco; Nicoletti, Ferdinando; Polesel, Jerry; Talamini, Renato; Bäsecke, Jörg; Mijatovic, Sanja; Maksimovic-Ivanic, Danijela; Milella, Michele; Tafuri, Agostino; Dulińska-Litewka, Joanna; Laidler, Piotr; D'Assoro, Antonio B.; Drobot, Lyudmyla; Umezawa, Kazuo; Montalto, Giuseppe; Cervello, Melchiorre; Demidenko, Zoya N.

    2012-01-01

    Over the past few years, significant advances have occurred in both our understanding of the complexity of signal transduction pathways as well as the isolation of specific inhibitors which target key components in those pathways. Furthermore critical information is being accrued regarding how genetic mutations can affect the sensitivity of various types of patients to targeted therapy. Finally, genetic mechanisms responsible for the development of resistance after targeted therapy are being discovered which may allow the creation of alternative therapies to overcome resistance. This review will discuss some of the highlights over the past few years on the roles of key signaling pathways in various diseases, the targeting of signal transduction pathways and the genetic mechanisms governing sensitivity and resistance to targeted therapies. PMID:23455493

  8. Aging of signal transduction pathways, and pathology

    PubMed Central

    Carlson, Morgan E.; Silva, Haroldo S.; Conboy, Irina M.

    2008-01-01

    The major cell signaling pathways, and their specific mechanisms of transduction, have been a subject of investigation for many years. As our understanding of these pathways advances, we find that they are evolutionarily well-conserved not only individually, but also at the level of their crosstalk and signal integration. Productive interactions within the key signal transduction networks determine success in embryonic organogenesis, and postnatal tissue repair throughout adulthood. However, aside from clues revealed through examining age-related degenerative diseases, much remains uncertain about imbalances within these pathways during normal aging. Further, little is known about the molecular mechanisms by which alterations in the major cell signal transduction networks cause age-related pathologies. The aim of this review is to describe the complex interplay between the Notch, TGFβ, WNT, RTK-Ras and Hh signaling pathways, with a specific focus on the changes introduced within these networks by the aging process, and those typical of age-associated human pathologies. PMID:18474281

  9. Interference of fisetin with targets of the nuclear factor-κB signal transduction pathway activated by Epstein-Barr virus encoded latent membrane protein 1.

    PubMed

    Li, Rong; Liang, Hong-Ying; Li, Ming-Yong; Lin, Chun-Yan; Shi, Meng-Jie; Zhang, Xiu-Juan

    2014-01-01

    Fisetin is an effective compound extracted from lacquer which has been used in the treatment of various diseases. Preliminary data indicate that it also exerts specific anti-cancer effects. However, the manner in which fisetin regulates cancer growth remains unknown. In this study, we elucidated interference of fisetin with targets of the nuclear factorκB signal transduction pathway activated by Epstein-Barr virus encoding latent membrane protein 1 (LMP1)in nasopharyngeal carcinoma (NPC) cells, Results showed that fisetin inhibited the survival rate of CNE-LMP1 cells and NF-κB activation caused by LMP1. Fisetin also suppressed nuclear translocation of NF-κB (p65) and IκBα phosphorylation, while inhibiting CyclinD1, all key targets of the NF-κB signal transduction pathway. It was suggested that interference effects of fisetin with signal transduction activated by LMP1 encoded by the Epstein-Barr virus may play an important role in its anticancer potential.

  10. Involvement of mitogen-activated protein kinase activation in the signal-transduction pathways of the soya bean oxidative burst.

    PubMed Central

    Taylor, A T; Kim, J; Low, P S

    2001-01-01

    The oxidative burst constitutes one of the most rapid defence responses characterized in the Plant Kingdom. We have observed that four distinct elicitors of the soya bean oxidative burst activate kinases of masses approximately 44 kDa and approximately 47 kDa. Evidence that these kinases regulate production of reactive oxygen species include: (i) their rapid activation by oxidative burst elicitors, (ii) their tight temporal correlation between activation/deactivation of the kinases and activation/deactivation of the oxidative burst, (iii) the identical pharmacological profile of kinase activation and oxidant production for 13 commonly used inhibitors, and (iv) the autologous activation of both kinases and oxidant production by calyculin A and cantharidin, two phosphatase inhibitors. Immunological and biochemical studies reveal that the activated 44 kDa and 47 kDa kinases are mitogen-activated protein (MAP) kinase family members. The kinases prefer myelin basic protein as a substrate, and they phosphorylate primarily on threonine residues. The kinases are themselves phosphorylated on tyrosine residues, and this phosphorylation is required for activity. Finally, both kinases are recognized by an antibody against activated MAP kinase immediately after (but not before) cell stimulation by elicitors. Based on these and other observations, a preliminary sequence of signalling steps linking elicitor stimulation, kinase activation and Ca(2+) entry, to initiation of oxidant production, is proposed. PMID:11311144

  11. Signal transduction pathways involved in mechanotransduction in bone cells

    SciTech Connect

    Liedert, Astrid . E-mail: astrid.liedert@uni-ulm.de; Kaspar, Daniela; Blakytny, Robert; Claes, Lutz; Ignatius, Anita

    2006-10-13

    Several in vivo and in vitro studies with different loading regimens showed that mechanical stimuli have an influence on proliferation and differentiation of bone cells. Prerequisite for this influence is the transduction of mechanical signals into the cell, a phenomenon that is termed mechanotransduction, which is essential for the maintenance of skeletal homeostasis in adults. Mechanoreceptors, such as the integrins, cadherins, and stretch-activated Ca{sup 2+} channels, together with various signal transduction pathways, are involved in the mechanotransduction process that ultimately regulates gene expression in the nucleus. Mechanotransduction itself is considered to be regulated by hormones, the extracellular matrix of the osteoblastic cells and the mode of the mechanical stimulus.

  12. Hedgehog Secretion and Signal Transduction in Vertebrates

    PubMed Central

    Ryan, Kaitlyn E.; Chiang, Chin

    2012-01-01

    Signaling by the Hedgehog (Hh) family of secreted proteins is essential for proper embryonic patterning and development. Dysregulation of Hh signaling is associated with a variety of human diseases ranging from developmental disorders such as holoprosencephaly to certain forms of cancer, including medulloblastoma and basal cell carcinoma. Genetic studies in flies and mice have shaped our understanding of Hh signaling and revealed that nearly all core components of the pathway are highly conserved. Although many aspects of the Drosophila Hh pathway are conserved in vertebrates, mechanistic differences between the two species have begun to emerge. Perhaps the most striking divergence in vertebrate Hh signaling is its dependence on the primary cilium, a vestigial organelle that is largely absent in flies. This minireview will provide an overview of Hh signaling and present recent insights into vertebrate Hh secretion, receptor binding, and signal transduction. PMID:22474285

  13. Methylmercury, an environmental electrophile capable of activation and disruption of the Akt/CREB/Bcl-2 signal transduction pathway in SH-SY5Y cells

    PubMed Central

    Unoki, Takamitsu; Abiko, Yumi; Toyama, Takashi; Uehara, Takashi; Tsuboi, Koji; Nishida, Motohiro; Kaji, Toshiyuki; Kumagai, Yoshito

    2016-01-01

    Methylmercury (MeHg) modifies cellular proteins via their thiol groups in a process referred to as “S-mercuration”, potentially resulting in modulation of the cellular signal transduction pathway. We examined whether low-dose MeHg could affect Akt signaling involved in cell survival. Exposure of human neuroblastoma SH-SY5Y cells of up to 2 μM MeHg phosphorylated Akt and its downstream signal molecule CREB, presumably due to inactivation of PTEN through S-mercuration. As a result, the anti-apoptotic protein Bcl-2 was up-regulated by MeHg. The activation of Akt/CREB/Bcl-2 signaling mediated by MeHg was, at least in part, linked to cellular defence because either pretreatment with wortmannin to block PI3K/Akt signaling or knockdown of Bcl-2 enhanced MeHg-mediated cytotoxicity. In contrast, increasing concentrations of MeHg disrupted Akt/CREB/Bcl-2 signaling. This phenomenon was attributed to S-mercuration of CREB through Cys286 rather than Akt. These results suggest that although MeHg is an apoptosis-inducing toxicant, this environmental electrophile is able to activate the cell survival signal transduction pathway at lower concentrations prior to apoptotic cell death. PMID:27357941

  14. Hedgehog Signal Transduction: Key Players, Oncogenic Drivers, and Cancer Therapy.

    PubMed

    Pak, Ekaterina; Segal, Rosalind A

    2016-08-22

    The Hedgehog (Hh) signaling pathway governs complex developmental processes, including proliferation and patterning within diverse tissues. These activities rely on a tightly regulated transduction system that converts graded Hh input signals into specific levels of pathway activity. Uncontrolled activation of Hh signaling drives tumor initiation and maintenance. However, recent entry of pathway-specific inhibitors into the clinic reveals mixed patient responses and thus prompts further exploration of pathway activation and inhibition. In this review, we share emerging insights into regulated and oncogenic Hh signaling, supplemented with updates on the development and use of Hh pathway-targeted therapies.

  15. Developing a synthetic signal transduction system in plants.

    PubMed

    Morey, Kevin J; Antunes, Mauricio S; Albrecht, Kirk D; Bowen, Tessa A; Troupe, Jared F; Havens, Keira L; Medford, June I

    2011-01-01

    One area of focus in the emerging field of plant synthetic biology is the manipulation of systems involved in sensing and response to environmental signals. Sensing and responding to signals, including ligands, typically involves biological signal transduction. Plants use a wide variety of signaling systems to sense and respond to their environment. One of these systems, a histidine kinase (HK) based signaling system, lends itself to manipulation using the tools of synthetic biology. Both plants and bacteria use HKs to relay signals, which in bacteria can involve as few as two proteins (two-component systems or TCS). HK proteins are evolutionarily conserved between plants and bacteria and plant HK components have been shown to be functional in bacteria. We found that this conservation also applies to bacterial HK components which can function in plants. This conservation of function led us to hypothesize that synthetic HK signaling components can be designed and rapidly tested in bacteria. These novel HK signaling components form the foundation for a synthetic signaling system in plants, but typically require modifications such as codon optimization and proper targeting to allow optimal function. We describe the process and methodology of producing a synthetic signal transduction system in plants. We discovered that the bacterial response regulator (RR) PhoB shows HK-dependent nuclear translocation in planta. Using this discovery, we engineered a partial synthetic pathway in which a synthetic promoter (PlantPho) is activated using a plant-adapted PhoB (PhoB-VP64) and the endogenous HK-based cytokinin signaling pathway. Building on this work, we adapted an input or sensing system based on bacterial chemotactic binding proteins and HKs, resulting in a complete eukaryotic signal transduction system. Input to our eukaryotic signal transduction system is provided by a periplasmic binding protein (PBP), ribose-binding protein (RBP). RBP interacts with the membrane

  16. LRRK2 overexpression alters glutamatergic presynaptic plasticity, striatal dopamine tone, postsynaptic signal transduction, motor activity and memory.

    PubMed

    Beccano-Kelly, Dayne A; Volta, Mattia; Munsie, Lise N; Paschall, Sarah A; Tatarnikov, Igor; Co, Kimberley; Chou, Patrick; Cao, Li-Ping; Bergeron, Sabrina; Mitchell, Emma; Han, Heather; Melrose, Heather L; Tapia, Lucia; Raymond, Lynn A; Farrer, Matthew J; Milnerwood, Austen J

    2015-03-01

    Mutations in leucine-rich repeat kinase 2 (Lrrk2) are the most common genetic cause of Parkinson's disease (PD), a neurodegenerative disorder affecting 1-2% of those >65 years old. The neurophysiology of LRRK2 remains largely elusive, although protein loss suggests a role in glutamatergic synapse transmission and overexpression studies show altered dopamine release in aged mice. We show that glutamate transmission is unaltered onto striatal projection neurons (SPNs) of adult LRRK2 knockout mice and that adult animals exhibit no detectable cognitive or motor deficits. Basal synaptic transmission is also unaltered in SPNs of LRRK2 overexpressing mice, but they do exhibit clear alterations to D2-receptor-mediated short-term synaptic plasticity, behavioral hypoactivity and impaired recognition memory. These phenomena are associated with decreased striatal dopamine tone and abnormal dopamine- and cAMP-regulated phosphoprotein 32 kDa signal integration. The data suggest that LRRK2 acts at the nexus of dopamine and glutamate signaling in the adult striatum, where it regulates dopamine levels, presynaptic glutamate release via D2-dependent synaptic plasticity and dopamine-receptor signal transduction. PMID:25343991

  17. LRRK2 overexpression alters glutamatergic presynaptic plasticity, striatal dopamine tone, postsynaptic signal transduction, motor activity and memory.

    PubMed

    Beccano-Kelly, Dayne A; Volta, Mattia; Munsie, Lise N; Paschall, Sarah A; Tatarnikov, Igor; Co, Kimberley; Chou, Patrick; Cao, Li-Ping; Bergeron, Sabrina; Mitchell, Emma; Han, Heather; Melrose, Heather L; Tapia, Lucia; Raymond, Lynn A; Farrer, Matthew J; Milnerwood, Austen J

    2015-03-01

    Mutations in leucine-rich repeat kinase 2 (Lrrk2) are the most common genetic cause of Parkinson's disease (PD), a neurodegenerative disorder affecting 1-2% of those >65 years old. The neurophysiology of LRRK2 remains largely elusive, although protein loss suggests a role in glutamatergic synapse transmission and overexpression studies show altered dopamine release in aged mice. We show that glutamate transmission is unaltered onto striatal projection neurons (SPNs) of adult LRRK2 knockout mice and that adult animals exhibit no detectable cognitive or motor deficits. Basal synaptic transmission is also unaltered in SPNs of LRRK2 overexpressing mice, but they do exhibit clear alterations to D2-receptor-mediated short-term synaptic plasticity, behavioral hypoactivity and impaired recognition memory. These phenomena are associated with decreased striatal dopamine tone and abnormal dopamine- and cAMP-regulated phosphoprotein 32 kDa signal integration. The data suggest that LRRK2 acts at the nexus of dopamine and glutamate signaling in the adult striatum, where it regulates dopamine levels, presynaptic glutamate release via D2-dependent synaptic plasticity and dopamine-receptor signal transduction.

  18. Activation of p21ras/MAPK signal transduction molecules decreases with age in mitogen-stimulated T cells from rats.

    PubMed

    Pahlavani, M A; Harris, M D; Richardson, A

    1998-04-10

    Signal transduction is ubiquitously involved in the initiation of physiological signals that lead to growth and proliferation of cells. The signaling cascade mediated by the mitogen-activated protein kinase (MAPK) is considered essential for T cell growth and function. Therefore, it was of interest to determine the influence of age on the induction of MAPK in mitogen-activated T cells. T cells from young (4-6 months) and old (24-26 months) rats responded to concanavalin A (Con A) stimulation by increasing MAPK, c-jun amino terminal kinase (JNK), and p21ras activities. The time course of induction of MAPK/JNK and p21ras activities was similar in T cells isolated from young and old rats. The induction of JNK activity did not change significantly with age; however, the induction of MAPK and p21ras activities was significantly less (50 to 65%) in T cells from old rats than in T cells from young rats. Although the relative protein levels of p42 and p44 MAPK did not change with age, the proportion of the phosphorylated p44 MAPK decreased with age. In addition, it was found that the in vitro kinase activities of the T cell receptor-associated protein tyrosine kinase Lck (p56Lck) and ZAP-70 but not Fyn (p59Fyn) were lower in T cells from old rats than in T cells from young rats. The decline in activities of these signaling molecules with age was not associated with changes in their corresponding protein levels. Thus, our results demonstrate that aging alters the activation of the signal transduction cascade that leads to T cell activation.

  19. Hog1 mitogen-activated protein kinase (MAPK) interrupts signal transduction between the Kss1 MAPK and the Tec1 transcription factor to maintain pathway specificity.

    PubMed

    Shock, Teresa R; Thompson, James; Yates, John R; Madhani, Hiten D

    2009-04-01

    In Saccharomyces cerevisiae, the mating, filamentous growth (FG), and high-osmolarity glycerol (HOG) mitogen-activated protein kinase (MAPK) signaling pathways share components and yet mediate distinct responses to different extracellular signals. Cross talk is suppressed between the mating and FG pathways because mating signaling induces the destruction of the FG transcription factor Tec1. We show here that HOG pathway activation results in phosphorylation of the FG MAPK, Kss1, and the MAPKK, Ste7. However, FG transcription is not activated because HOG signaling prevents the activation of Tec1. In contrast to the mating pathway, we find that the mechanism involves the inhibition of DNA binding by Tec1 rather than its destruction. We also find that nuclear accumulation of Tec1 is not affected by HOG signaling. Inhibition by Hog1 is apparently indirect since it does not require any of the consensus S/TP MAPK phosphorylation sites on Tec1, its DNA-binding partner Ste12, or the associated regulators Dig1 or Dig2. It also does not require the consensus MAPK sites of the Ste11 activator Ste50, in contrast to a recent proposal for a role for negative feedback in specificity. Our results demonstrate that HOG signaling interrupts the FG pathway signal transduction between the phosphorylation of Kss1 and the activation of DNA binding by Tec1. PMID:19218425

  20. Human conjunctival epithelial cell responses to platelet-activating factor (PAF): signal transduction and release of proinflammatory cytokines

    PubMed Central

    Xu, Shouxi; Hellberg, Peggy E.; Pang, Iok-Hou; Gamache, Daniel A.; Yanni, John M.

    2009-01-01

    Purpose The aims of the study were to characterize the signal transduction responses to platelet-activating factor (PAF) and to monitor the downstream effects of PAF on the production of proinflammatory cytokines in human conjunctival epithelial cells (HCECs). Methods The generation of inositol phosphates ([3H]IPs) from [3H]phosphoinositide (PI) hydrolysis and the mobilization of intracellular calcium ([Ca2+]i) were evaluated using ion exchange chromatography and Fura-2 fluorescence techniques, respectively. The production of the cytokines (interleukin-6 [IL-6], interleukin-8 [IL-8], and granulocyte macrophage colony-stimulating factor [GM-CSF]) from PAF-stimulated HCECs was quantified using specific ELISA assays. Specific PAF antagonists were used to study the pharmacological aspects of PAF actions in HCECs. Results PAF (100 nM) maximally stimulated PI turnover in HCECs by 2.3±0.02 fold (n=21) above basal levels and with a potency (EC50) of 5.9±1.7 nM (n=4). PAF or its stabilized analog, methyl carbamyl (mc)PAF (EC50=0.8 nM), rapidly mobilized [Ca2+]i, which peaked within 30–60 s and remained elevated for 3 min. PAF (10 nM–1 µM) stimulated the release of the proinflammatory cytokines, IL-6, IL-8, and GM-CSF, 1.4–3.5 fold above basal levels. The effects of PAF (100 nM) on PI turnover and [Ca2+]i were potently antagonized by the PAF antagonists, 1-o-hexadecyl-2-o-acetyl–sn-glycero-3-phospho (N,N,N-trimethyl) hexanolamine (IC50=0.69 µM; Ki=38 nM), methyl 2-(phenylthio)ethyl-1,4-dihydro-2,4,6-trimethyl-pyridine-3,5-dicsrboxylate (PCA-42481; IC50=0.89 µM; Ki=50 nM), rac-3-(N-octadecylcarbomoyl)-2-methoxy) propyl-(2-thiazolioethyl) phosphate (CV-3988; IC50=13 µM; Ki=771 nM), and (+/−)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one HCl (SM-10661; IC50=14 µM; Ki=789 nM [n=3 for each antagonist]). PAF-induced production of IL-6, IL-8, and GM-CSF from HCECs was also blocked by these PAF antagonists (IC50=4.6– 8.6 µM). Conclusions HCECs respond to PAF by

  1. Signal transduction images in human brain by positron emission tomography

    SciTech Connect

    Imahori, Y.; Fujii, R.; Ueda, S.

    1994-05-01

    Analysis of changes in intracellular signal transduction will provide clear images of the projected target neurons. We have recently developed a technique which allows second-messenger imaging of changes in intracellular signal transduction which is activated in parallel with phosphoinositide (PI) turnover. Using carbon-11-labeled 1,2-diacylglycerol (DAG), we have recently succeeded in making an image of intracellular signal transduction during the course of synaptic transmission in human brains. When five healthy volunteers were examined by this technique, they had high activity in the associate field, in particular the prefrontal area. In the absence of paradigm loading, the associate field was unilaterally active, and human subjects showed predominant activity in the right prefrontal area. Activation of the ipsilateral supraorbital region and the superior temporal area was also seen at the same time. In conclusion, no previous study has directly demonstrated the unilateral predominance of the activity in the associate fields (projected target area) and the accompanying areas. Unlike the conventional positron-labeled compounds which did not permit visualization of activation of the associate fields, our technique can measure the PI turnover, as a postsynaptic response, and thus provide clear images of the projected target nerve cells in relation to higher cortical function in human brain.

  2. Striatal signal transduction and drug addiction.

    PubMed

    Philibin, Scott D; Hernandez, Adan; Self, David W; Bibb, James A

    2011-01-01

    Drug addiction is a severe neuropsychiatric disorder characterized by loss of control over motivated behavior. The need for effective treatments mandates a greater understanding of the causes and identification of new therapeutic targets for drug development. Drugs of abuse subjugate normal reward-related behavior to uncontrollable drug-seeking and -taking. Contributions of brain reward circuitry are being mapped with increasing precision. The role of synaptic plasticity in addiction and underlying molecular mechanisms contributing to the formation of the addicted state are being delineated. Thus we may now consider the role of striatal signal transduction in addiction from a more integrative neurobiological perspective. Drugs of abuse alter dopaminergic and glutamatergic neurotransmission in medium spiny neurons of the striatum. Dopamine receptors important for reward serve as principle targets of drugs abuse, which interact with glutamate receptor signaling critical for reward learning. Complex networks of intracellular signal transduction mechanisms underlying these receptors are strongly stimulated by addictive drugs. Through these mechanisms, repeated drug exposure alters functional and structural neuroplasticity, resulting in transition to the addicted biological state and behavioral outcomes that typify addiction. Ca(2+) and cAMP represent key second messengers that initiate signaling cascades, which regulate synaptic strength and neuronal excitability. Protein phosphorylation and dephosphorylation are fundamental mechanisms underlying synaptic plasticity that are dysregulated by drugs of abuse. Increased understanding of the regulatory mechanisms by which protein kinases and phosphatases exert their effects during normal reward learning and the addiction process may lead to novel targets and pharmacotherapeutics with increased efficacy in promoting abstinence and decreased side effects, such as interference with natural reward, for drug addiction.

  3. Phosphoglycerolipids are master players in plant hormone signal transduction.

    PubMed

    Janda, Martin; Planchais, Severine; Djafi, Nabila; Martinec, Jan; Burketova, Lenka; Valentova, Olga; Zachowski, Alain; Ruelland, Eric

    2013-06-01

    Phosphoglycerolipids are essential structural constituents of membranes and some also have important cell signalling roles. In this review, we focus on phosphoglycerolipids that are mediators in hormone signal transduction in plants. We first describe the structures of the main signalling phosphoglycerolipids and the metabolic pathways that generate them, namely the phospholipase and lipid kinase pathways. In silico analysis of Arabidopsis transcriptome data provides evidence that the genes encoding the enzymes of these pathways are transcriptionally regulated in responses to hormones, suggesting some link with hormone signal transduction. The involvement of phosphoglycerolipid signalling in the early responses to abscisic acid, salicylic acid and auxins is then detailed. One of the most important signalling lipids in plants is phosphatidic acid. It can activate or inactivate protein kinases and/or protein phosphatases involved in hormone signalling. It can also activate NADPH oxidase leading to the production of reactive oxygen species. We will interrogate the mechanisms that allow the activation/deactivation of the lipid pathways, in particular the roles of G proteins and calcium. Mediating lipids thus appear as master players of cell signalling, modulating, if not controlling, major transducing steps of hormone signals.

  4. Signal transduction by the growth hormone receptor

    SciTech Connect

    Waters, M.J.; Rowlinson, S.W.; Clarkson, R.W.

    1994-12-31

    It has been proposed that dimerization of identical receptor subunits by growth hormone (GH) is the mechanism of signal transduction across the cell membrane. We present here data with analogs of porcine GH (pGH), with GH receptors (GHR) mutated in the dimerization domain and with monoclonal antibodies to the GHR which indicate that dimerization is necessary but not sufficient for transduction. We also report nuclear uptake of GH both in vivo and in vitro, along with nuclear localization of the receptor and GH-binding protein (GHBP). This suggests that GH acts directly at the nucleus, and one possible target for this action is a rapid increase in transcription of C/EBP delta seen in 3T3-F442A cells in response to GH. This tyrosine kinase-dependent event may be an archetype for induction of other immediate early gene transcription factors which then interact to determine the programming of the subsequent transcriptional response to GH. 29 refs., 1 fig., 1 tab.

  5. Mechanical signal transduction in skeletal muscle growth and adaptation.

    PubMed

    Tidball, James G

    2005-05-01

    The adaptability of skeletal muscle to changes in the mechanical environment has been well characterized at the tissue and system levels, but the mechanisms through which mechanical signals are transduced to chemical signals that influence muscle growth and metabolism remain largely unidentified. However, several findings have suggested that mechanical signal transduction in muscle may occur through signaling pathways that are shared with insulin-like growth factor (IGF)-I. The involvement of IGF-I-mediated signaling for mechanical signal transduction in muscle was originally suggested by the observations that muscle releases IGF-I on mechanical stimulation, that IGF-I is a potent agent for promoting muscle growth and affecting phenotype, and that IGF-I can function as an autocrine hormone in muscle. Accumulating evidence shows that at least two signaling pathways downstream of IGF-I binding can influence muscle growth and adaptation. Signaling via the calcineurin/nuclear factor of activated T-cell pathway has been shown to have a powerful influence on promoting the slow/type I phenotype in muscle but can also increase muscle mass. Neural stimulation of muscle can activate this pathway, although whether neural activation of the pathway can occur independent of mechanical activation or independent of IGF-I-mediated signaling remains to be explored. Signaling via the Akt/mammalian target of rapamycin pathway can also increase muscle growth, and recent findings show that activation of this pathway can occur as a response to mechanical stimulation applied directly to muscle cells, independent of signals derived from other cells. In addition, mechanical activation of mammalian target of rapamycin, Akt, and other downstream signals is apparently independent of autocrine factors, which suggests that activation of the mechanical pathway occurs independent of muscle-mediated IGF-I release.

  6. Nonequilibrium phase transitions in biomolecular signal transduction

    NASA Astrophysics Data System (ADS)

    Smith, Eric; Krishnamurthy, Supriya; Fontana, Walter; Krakauer, David

    2011-11-01

    We study a mechanism for reliable switching in biomolecular signal-transduction cascades. Steady bistable states are created by system-size cooperative effects in populations of proteins, in spite of the fact that the phosphorylation-state transitions of any molecule, by means of which the switch is implemented, are highly stochastic. The emergence of switching is a nonequilibrium phase transition in an energetically driven, dissipative system described by a master equation. We use operator and functional integral methods from reaction-diffusion theory to solve for the phase structure, noise spectrum, and escape trajectories and first-passage times of a class of minimal models of switches, showing how all critical properties for switch behavior can be computed within a unified framework.

  7. Key cancer cell signal transduction pathways as therapeutic targets.

    PubMed

    Bianco, Roberto; Melisi, Davide; Ciardiello, Fortunato; Tortora, Giampaolo

    2006-02-01

    Growth factor signals are propagated from the cell surface, through the action of transmembrane receptors, to intracellular effectors that control critical functions in human cancer cells, such as differentiation, growth, angiogenesis, and inhibition of cell death and apoptosis. Several kinases are involved in transduction pathways via sequential signalling activation. These kinases include transmembrane receptor kinases (e.g., epidermal growth factor receptor EGFR); or cytoplasmic kinases (e.g., PI3 kinase). In cancer cells, these signalling pathways are often altered and results in a phenotype characterized by uncontrolled growth and increased capability to invade surrounding tissue. Therefore, these crucial transduction molecules represent attractive targets for cancer therapy. This review will summarize current knowledge of key signal transduction pathways, that are altered in cancer cells, as therapeutic targets for novel selective inhibitors. The most advanced targeted agents currently under development interfere with function and expression of several signalling molecules, including the EGFR family; the vascular endothelial growth factor and its receptors; and cytoplasmic kinases such as Ras, PI3K and mTOR.

  8. Melatonin receptor activation regulates GnRH gene expression and secretion in GT1-7 GnRH neurons. Signal transduction mechanisms.

    PubMed

    Roy, Deboleena; Belsham, Denise D

    2002-01-01

    Melatonin plays a significant role in the control of the hypothalamic-pituitary-gonadal axis. Using the GT1-7 cell line, an in vitro model of GnRH-secreting neurons of the hypothalamus, we examined the potential signal transduction pathways activated by melatonin directly at the level of the GT1-7 neuron. We found that melatonin inhibits forskolin-stimulated adenosine 3'-, 5'-cyclic monophosphate accumulation in GT1-7 cells through an inhibitory G protein. Melatonin induced protein kinase C activity by 1.65-fold over basal levels, increased the phosphorylation of extracellular signal-regulated kinase 1 and 2 proteins, and activated c-fos and junB mRNA expression in GT1-7 cells. Using the protein kinase A inhibitor H-89, the protein kinase C inhibitor bisindolylmaleimide, and the mitogen-activated protein kinase kinase inhibitor PD98059, we found that the melatonin-mediated cyclical regulation of GnRH mRNA expression may involve the protein kinase C and the extracellular signal-regulated kinase 1 and 2 pathways, but not the protein kinase A pathway. We found that melatonin suppresses GnRH secretion by approximately 45% in the GT1-7 neurons. However, in the presence of the inhibitors H-89, bisindolylmaleimide, and PD98059 melatonin was unable to suppress GnRH secretion. These results provide insights into the potential signal transduction mechanisms involved in the control of GnRH gene expression and secretion by melatonin.

  9. Signal transduction of aortic and carotid sinus baroreceptors is not modified by central command during spontaneous motor activity in decerebrate cats.

    PubMed

    Matsukawa, Kanji; Ishii, Kei; Kadowaki, Akito; Ishida, Tomoko; Idesako, Mitsuhiro; Liang, Nan

    2014-05-15

    Our laboratory has suggested that central command provides selective inhibition of the cardiomotor component of aortic baroreflex at the start of exercise, preserving carotid sinus baroreflex. It is postulated that central command may modify the signal transduction of aortic baroreceptors, so as to decrease aortic baroreceptor input to the cardiovascular centers, and, thereby, can cause the selective inhibition of aortic baroreflex. To test the hypothesis, we directly analyzed the responses in multifiber aortic nerve activity (AoNA) and carotid sinus nerve activity (CsNA) during spontaneous motor activity in decerebrate, paralyzed cats. The increases of 62-104% in mean AoNA and CsNA were found during spontaneous motor activity, in proportion to a rise of 35 ± 3 mmHg (means ± SE) in mean arterial blood pressure (MAP), and had an attenuating tendency by restraining heart rate (HR) at the lower intrinsic frequency of 154 ± 6 beats/min. Brief occlusion of the abdominal aorta was conducted before and during spontaneous motor activity to produce a mechanically evoked increase in MAP and, thereby, to examine the stimulus-response relationship of arterial baroreceptors. Although the sensitivity of the MAP-HR baroreflex curve was markedly blunted during spontaneous motor activity, the stimulus-response relationships of AoNA and CsNA were not influenced by spontaneous motor activity, irrespective of the absence or presence of the HR restraint. Thus, it is concluded that aortic and carotid sinus baroreceptors can code beat-by-beat blood pressure during spontaneous motor activity in decerebrate cats and that central command is unlikely to modulate the signal transduction of arterial baroreceptors.

  10. HC fragment (C-terminal portion of the heavy chain) of tetanus toxin activates protein kinase C isoforms and phosphoproteins involved in signal transduction.

    PubMed Central

    Gil, C; Chaib-Oukadour, I; Blasi, J; Aguilera, J

    2001-01-01

    A recent report [Gil, Chaib-Oukadour, Pelliccioni and Aguilera (2000) FEBS Lett. 481, 177-182] describes activation of signal transduction pathways by tetanus toxin (TeTx), a Zn(2+)-dependent endopeptidase synthesized by the Clostridium tetani bacillus, which is responsible for tetanus disease. In the present work, specific activation of protein kinase C (PKC) isoforms and of intracellular signal-transduction pathways, which include nerve-growth-factor (NGF) receptor trkA, phospholipase C(PLC)gamma-1 and extracellular regulated kinases (ERKs) 1 and 2, by the recombinant C-terminal portion of the TeTx heavy chain (H(C)-TeTx) is reported. The activation of PKC isoforms was assessed through their translocation from the soluble (cytosolic) compartment to the membranous compartment, showing that clear translocation of PKC-alpha, -beta, -gamma and -delta isoforms exists, whereas PKC-epsilon showed a slight decrease in its soluble fraction immunoreactivity. The PKC-zeta isoform showed no consistent response. Using immunoprecipitation assays against phosphotyrosine residues, time- and dose-dependent increases in tyrosine phosphorylation were observed in the trkA receptor, PLCgamma-1 and ERK-1/2. The effects shown by the H(C)-TeTx fragment on tyrosine phosphorylation were compared with the effects produced by NGF. The trkA and ERK-1/2 activation were corroborated using phospho-specific antibodies against trkA phosphorylated on Tyr(490), and antibodies against Thr/Tyr phosphorylated ERK-1/2. Moreover, PLCgamma-1 phosphorylation was supported by its H(C)-TeTx-induced translocation to the membranous compartment, an event related to PLCgamma-1 activation. Since H(C)-TeTx is the domain responsible for membrane binding and lacks catalytic activity, the activations described here must be exclusively triggered by the interaction of TeTx with a membrane component. PMID:11336640

  11. Signal transduction in macrophages by glycosylphosphatidylinositols of Plasmodium, Trypanosoma, and Leishmania: Activation of protein tyrosine kinases and protein kinase C by inositolglycan and diacylglycerol moieties

    PubMed Central

    Tachado, Souvenir D.; Gerold, Peter; Schwarz, Ralph; Novakovic, Suzanna; McConville, Malcolm; Schofield, Louis

    1997-01-01

    The perturbation of various glycosylphosphatidylinositol (GPI)-anchored surface proteins imparts profound regulatory signals to macrophages, lymphocytes and other cell types. The specific contribution of the GPI moieties to these events however is unclear. This study demonstrates that purified GPIs of Plasmodium falciparum, Trypanosoma brucei, and Leishmania mexicana origin are sufficient to initiate signal transduction when added alone to host cells as chemically defined agonists. GPIs (10 nM–1 μM) induce rapid activation of the protein tyrosine kinase (PTK) p59hck in macrophages. The minimal structural requirement for PTK activation is the evolutionarily conserved core glycan sequence Manα1-2Manα1-6Manα1-4GlcN1-6myo-inositol. GPI-associated diacylglycerols independently activate the calcium-independent ɛ isoform of protein kinase C. Both signals collaborate in regulating the downstream NF-κB/rel-dependent gene expression of interleukin 1α, tumor necrosis factor (TNF) α, and inducible NO synthase. The alkylacylglycerol-containing iM4 GIPL of L. mexicana, however, is unable to activate protein kinase C and inhibits TNF expression in response to other agonists, establishing signaling specificity among structurally distinct GPIs. GPI alone appears sufficient to mimic the activities of malaria parasite extracts in the signaling pathway leading to TNF expression. A mAb to GPI blocks TNF induction by parasite extracts indicating that GPI is a necessary agent in this response. As protozoal GPIs are closely related to their mammalian counterparts, the data indicate that GPIs do indeed constitute a novel outside-in signaling system, acting as both agonists and second messenger substrates, and imparting at least two separate signals through the structurally distinct glycan and fatty acid domains. These activities may underlie aspects of pathology and immune regulation in protozoal infections. PMID:9108098

  12. Alteration of EGFR Spatiotemporal Dynamics Suppresses Signal Transduction

    PubMed Central

    Turk, Harmony F.; Barhoumi, Rola; Chapkin, Robert S.

    2012-01-01

    The epidermal growth factor receptor (EGFR), which regulates cell growth and survival, is integral to colon tumorigenesis. Lipid rafts play a role in regulating EGFR signaling, and docosahexaenoic acid (DHA) is known to perturb membrane domain organization through changes in lipid rafts. Therefore, we investigated the mechanistic link between EGFR function and DHA. Membrane incorporation of DHA into immortalized colonocytes altered the lateral organization of EGFR. DHA additionally increased EGFR phosphorylation but paradoxically suppressed downstream signaling. Assessment of the EGFR-Ras-ERK1/2 signaling cascade identified Ras GTP binding as the locus of the DHA-induced disruption of signal transduction. DHA also antagonized EGFR signaling capacity by increasing receptor internalization and degradation. DHA suppressed cell proliferation in an EGFR-dependent manner, but cell proliferation could be partially rescued by expression of constitutively active Ras. Feeding chronically-inflamed, carcinogen-injected C57BL/6 mice a fish oil containing diet enriched in DHA recapitulated the effects on the EGFR signaling axis observed in cell culture and additionally suppressed tumor formation. We conclude that DHA-induced alteration in both the lateral and subcellular localization of EGFR culminates in the suppression of EGFR downstream signal transduction, which has implications for the molecular basis of colon cancer prevention by DHA. PMID:22761867

  13. Inositol trisphosphate, a novel second messenger in cellular signal transduction

    NASA Astrophysics Data System (ADS)

    Berridge, Michael J.; Irvine, Robin F.

    1984-11-01

    There has recently been rapid progress in understanding receptors that generate intracellular signals from inositol lipids. One of these lipids, phosphatidylinositol 4,5-bisphosphate, is hydrolysed to diacylglycerol and inositol trisphosphate as part of a signal transduction mechanism for controlling a variety of cellular processes including secretion, metabolism, phototransduction and cell proliferation. Diacylglycerol operates within the plane of the membrane to activate protein kinase C, whereas inositol trisphosphate is released into the cytoplasm to function as a second messenger for mobilizing intracellular calcium.

  14. Bis(hinokitiolato)zinc complex ([Zn(hkt)2]) activates Akt/protein kinase B independent of insulin signal transduction.

    PubMed

    Naito, Yuki; Yoshikawa, Yutaka; Masuda, Kazufumi; Yasui, Hiroyuki

    2016-07-01

    Since many Zn complexes have been developed to enhance the insulin-like activity and increase the exposure and residence of Zn in the animal body, these complexes are recognized as one of the new candidates with action mechanism different from existing anti-diabetic drugs. However, the molecular mechanism by which Zn complexes exert an anti-DM effect is unknown. Therefore, we evaluated the activity of Zn complexes, especially related to the phosphorylation of insulin signaling pathway components. We focused on the insulin-like effects of the bis(hinokitiolato)zinc complex, [Zn(hkt)2], using 3T3-L1 adipocytes. [Zn(hkt)2] was taken up by cells and induced Akt phosphorylation in a time-dependent manner. Additionally, it showed inhibitory activity against PTP1B and PTEN, which are major negative regulators of insulin signaling. It did not promote the phosphorylation of IR (insulin receptor)-β or IRS (insulin receptor substrate)-1 by itself, but in combination with insulin, it enhanced the phosphorylation of IRβ. We conclude that [Zn(hkt)2] has effects on the proteins of insulin signaling pathway without insulin receptor mediation, and [Zn(hkt)2] promotes insulin function and shows the anti-DM effects. Thus, [Zn(hkt)2] may be the basis for improved DM treatments.

  15. Bis(hinokitiolato)zinc complex ([Zn(hkt)2]) activates Akt/protein kinase B independent of insulin signal transduction.

    PubMed

    Naito, Yuki; Yoshikawa, Yutaka; Masuda, Kazufumi; Yasui, Hiroyuki

    2016-07-01

    Since many Zn complexes have been developed to enhance the insulin-like activity and increase the exposure and residence of Zn in the animal body, these complexes are recognized as one of the new candidates with action mechanism different from existing anti-diabetic drugs. However, the molecular mechanism by which Zn complexes exert an anti-DM effect is unknown. Therefore, we evaluated the activity of Zn complexes, especially related to the phosphorylation of insulin signaling pathway components. We focused on the insulin-like effects of the bis(hinokitiolato)zinc complex, [Zn(hkt)2], using 3T3-L1 adipocytes. [Zn(hkt)2] was taken up by cells and induced Akt phosphorylation in a time-dependent manner. Additionally, it showed inhibitory activity against PTP1B and PTEN, which are major negative regulators of insulin signaling. It did not promote the phosphorylation of IR (insulin receptor)-β or IRS (insulin receptor substrate)-1 by itself, but in combination with insulin, it enhanced the phosphorylation of IRβ. We conclude that [Zn(hkt)2] has effects on the proteins of insulin signaling pathway without insulin receptor mediation, and [Zn(hkt)2] promotes insulin function and shows the anti-DM effects. Thus, [Zn(hkt)2] may be the basis for improved DM treatments. PMID:27251140

  16. Development of Th17-associated interstitial kidney inflammation in lupus-prone mice lacking the gene encoding Signal Transduction and Activator of Transcription-1 (STAT-1)

    PubMed Central

    Yiu, Gloria; Rasmussen, Tue Kruse; Ajami, Bahareh; Haddon, David J.; Chu, Alvina D.; Tangsombatvisit, Stephanie; Haynes, Winston A.; Diep, Vivian; Steinman, Larry; Faix, James; Utz, Paul J.

    2016-01-01

    Type I interferon (IFN-I) signaling is a central pathogenic pathway in Systemic Lupus Erythematosus (SLE), and therapeutics targeting IFN-I signaling are in development. Multiple proteins with overlapping function participate in IFN signaling, but the signaling events downstream of receptor engagement are unclear. We employed highly-multiplexed assays to characterize autoantibody production, cytokine/chemokine profiles, and Signal Transduction and Activators of Transcription (STAT) phosphorylation to investigate the individual roles of IFNAR2, IRF9 and STAT1 in MRL/lpr (lpr) mice. Surprisingly, we found that Stat1−/−, but not Irf9−/− or Ifnar2−/− mice, developed interstitial nephritis characterized by infiltration with RORγT+ lymphocytes, macrophages and eosinophils. Despite pronounced interstitial kidney disease and abnormal kidney function, Stat1−/− mice had decreased proteinuria, glomerulonephritis and autoantibody production. Phospho-specific flow cytometry (phosphoflow) revealed shunting of STAT phosphorylation from STAT1 to STAT3/4. In summary, we describe unique contributions of STAT1 to pathology in different kidney compartments, and provide novel insight into tubulointerstitial nephritis (TIN) a poorly understood complication that predicts end-stage kidney disease in SLE patients. PMID:26636548

  17. Modulation of both activator protein-1 and nuclear factor-kappa B signal transduction of human T cells by amiodarone

    PubMed Central

    Cheng, Shu-Meng; Lin, Wei-Hsiang; Lin, Chin-Sheng; Ho, Ling-Jun; Tsai, Tsung-Neng; Wu, Chun-Hsien; Lai, Jenn-Haung

    2015-01-01

    Amiodarone, a common and effective antiarrhythmic drug, has been reported to have anti-inflammatory effects such as reducing the activation and movement of neutrophils. However, its effects on human T cells remain unclear. The aim of this study was to elucidate the effects and possible underlying mechanisms of amiodarone on human T cells. We isolated human primary T cells from the peripheral blood of healthy volunteers and performed enzyme-linked immunosorbent assay (ELISA), flow cytometry, electrophoretic mobility shift assay, luciferase assay, and Western blotting to evaluate the modulatory effects of amiodarone on human T cells. We found that amiodarone dose dependently inhibited the production of cytokines, including interleukin-2 (IL-2), IL-4, tumor necrosis factor-alpha, and interferon-gamma in activated human T cells. By flow cytometry, we demonstrated that amiodarone suppressed the expression of IL-2 receptor-alpha (CD25) and CD69, the cell surface markers of activated T cells. Moreover, molecular investigations revealed that amiodarone down-regulated activator protein-1 (AP-1) and nuclear factor kappa-B (NF-κB) DNA-binding activities in activated human T cells and also inhibited DNA binding and transcriptional activities of both AP-1 and NF-κB in Jurkat cells. Finally, by Western blotting, we showed that amiodarone reduced the activation of c-Jun NH2-terminal protein kinase and P38 mitogen-activated protein kinase, and suppressed stimuli-induced I-kappa B-alpha degradation in activated human T cells. Through regulation of AP-1 and NF-κB signaling, amiodarone inhibits cytokine production and T cell activation. These results show the pleiotropic effects of amiodarone on human T cells and suggest its therapeutic potential in inflammation-related cardiovascular disorders. PMID:25073960

  18. Signal, Transduction, and the Hematopoietic Stem Cell

    PubMed Central

    Louria-Hayon, Igal

    2014-01-01

    The hematopoietic stem cell (HSC) is a unique cell positioned highest in the hematopoietic hierarchical system. The HSC has the ability to stay in quiescence, to self-renew, or to differentiate and generate all lineages of blood cells. The path to be actualized is influenced by signals that derive from the cell’s microenvironment, which activate molecular pathways inside the cell. Signaling pathways are commonly organized through inducible protein–protein interactions, mediated by adaptor proteins that link activated receptors to cytoplasmic effectors. This review will focus on the signaling molecules and how they work in concert to determine the HSC’s fate. PMID:25386349

  19. Similarities and differences in signal transduction by interleukin 4 and interleukin 13: analysis of Janus kinase activation.

    PubMed

    Keegan, A D; Johnston, J A; Tortolani, P J; McReynolds, L J; Kinzer, C; O'Shea, J J; Paul, W E

    1995-08-15

    The cytokines interleukin (IL) 4 and IL-13 induce many of the same biological responses, including class switching to IgE and induction of major histocompatibility complex class II antigens and CD23 on human B cells. It has recently been shown that IL-4 induces the tyrosine phosphorylation of a 170-kDa protein, a substrate called 4PS, and of the Janus kinase (JAK) family members JAK1 and JAK3. Because IL-13 has many functional effects similar to those of IL-4, we compared the ability of IL-4 and IL-13 to activate these signaling molecules in the human multifactor-dependent cell line TF-1. In this report we demonstrate that both IL-4 and IL-13 induced the tyrosine phosphorylation of 4PS and JAK1. Interestingly, although IL-4 induced the tyrosine phosphorylation of JAK3, we did not detect JAK3 phosphorylation in response to IL-13. These data suggest that IL-4 and IL-13 signal in similar ways via the activation of JAK1 and 4PS. However, our data further indicate that there are significant differences because IL-13 does not activate JAK3.

  20. EDITORIAL: Special section on signal transduction Special section on signal transduction

    NASA Astrophysics Data System (ADS)

    Shvartsman, Stanislav

    2012-08-01

    This special section of Physical Biology focuses on multiple aspects of signal transduction, broadly defined as the study of the mechanisms by which cells communicate with their environment. Mechanisms of cell communication involve detection of incoming signals, which can be chemical, mechanical or electromagnetic, relaying these signals to intracellular processes, such as cytoskeletal networks or gene expression systems, and, ultimately, converting these signals to responses such as cell differentiation or death. Given the multiscale nature of signal transduction systems, they must be studied at multiple levels, from the identities and structures of molecules comprising signal detection and interpretation networks, to the systems-level properties of these networks. The 11 papers in this special section illustrate some of the most exciting aspects of signal transduction research. The first two papers, by Marie-Anne Félix [1] and by Efrat Oron and Natalia Ivanova [2], focus on cell-cell interactions in developing tissues, using vulval patterning in worm and cell fate specification in mammalian embryos as prime examples of emergent cell behaviors. Next come two papers from the groups of Julio Saez-Rodriguez [3] and Kevin Janes [4]. These papers discuss how the causal relationships between multiple components of signaling systems can be inferred using multivariable statistical analysis of empirical data. An authoritative review by Zarnitsyna and Zhu [5] presents a detailed discussion of the sequence of signaling events involved in T-cell triggering. Once the structure and components of the signaling systems are determined, they can be modeled using approaches that have been successful in other physical sciences. As two examples of such approaches, reviews by Rubinstein [6] and Kholodenko [7], present reaction-diffusion models of cell polarization and thermodynamics-based models of gene regulation. An important class of models takes the form of enzymatic networks

  1. A novel label-free fluorescence strategy for methyltransferase activity assay based on dsDNA-templated copper nanoparticles coupled with an endonuclease-assisted signal transduction system.

    PubMed

    Lai, Q Q; Liu, M D; Gu, C C; Nie, H G; Xu, X J; Li, Z H; Yang, Z; Huang, S M

    2016-02-21

    Evaluating DNA methyltransferase (MTase) activity has received considerable attention due to its significance in the fields of early cancer clinical diagnostics and drug discovery. Herein, we proposed a novel label-free fluorescence method for MTase activity assay by coupling double-stranded DNA (dsDNA)-templated copper nanoparticles (CuNPs) with an endonuclease-assisted signal transduction system. In this strategy, dsDNA molecules were first methylated by DNA adenine methylation (Dam) MTase and then cleaved by the methylation-sensitive restriction endonuclease DpnI. The cleaved DNA fragments could not act as efficient templates for the formation of fluorescent CuNPs and thus no fluorescence signal was produced. Under optimized experimental conditions, the developed strategy exhibited a sensitive fluorescence response to Dam MTase activity. This strategy was also demonstrated to provide an excellent platform to the inhibitor screening for Dam MTase. These results demonstrated the great potential for the practical applications of the proposed strategy for Dam MTase activity assay. PMID:26764536

  2. The mechanism of signal transduction by two-component systems.

    PubMed

    Casino, Patricia; Rubio, Vicente; Marina, Alberto

    2010-12-01

    Two-component systems, composed of a homodimeric histidine kinase (HK) and a response regulator (RR), are major signal transduction devices in bacteria. Typically the signal triggers HK autophosphorylation at one His residue, followed by phosphoryl transfer from the phospho-His to an Asp residue in the RR. Signal extinction frequently involves phospho-RR dephosphorylation by a phosphatase activity of the HK. Our understanding of these reactions and of the determinants of partner specificity among HK-RR couples has been greatly increased by recent crystal structures and biochemical experiments on HK-RR complexes. Cis-autophosphorylation (one subunit phosphorylates itself) occurs in some HKs while trans-autophosphorylation takes place in others. We review and integrate this new information, discuss the mechanism of the three reactions and propose a model for transmembrane signaling by these systems.

  3. Melusin Promotes a Protective Signal Transduction Cascade in Stressed Hearts

    PubMed Central

    Sorge, Matteo; Brancaccio, Mara

    2016-01-01

    Melusin is a chaperone protein selectively expressed in heart and skeletal muscles. Melusin expression levels correlate with cardiac function in pre-clinical models and in human patients with aortic stenosis. Indeed, previous studies in several animal models indicated that Melusin plays a broad cardioprotective role in different pathological conditions. Chaperone proteins, besides playing a role in protein folding, are also able to facilitate supramolecular complex formation and conformational changes due to activation/deactivation of signaling molecules. This role sets chaperone proteins as crucial regulators of intracellular signal transduction pathways. In particular Melusin activates AKT and ERK1/2 signaling, protects cardiomyocytes from apoptosis and induces a compensatory hypertrophic response in several pathological conditions. Therefore, selective delivery of the Melusin gene in heart via cardiotropic adenoviral associated virus serotype 9 (AAV9), may represent a new promising gene-therapy approach for different cardiac pathologies. PMID:27672636

  4. Melusin Promotes a Protective Signal Transduction Cascade in Stressed Hearts

    PubMed Central

    Sorge, Matteo; Brancaccio, Mara

    2016-01-01

    Melusin is a chaperone protein selectively expressed in heart and skeletal muscles. Melusin expression levels correlate with cardiac function in pre-clinical models and in human patients with aortic stenosis. Indeed, previous studies in several animal models indicated that Melusin plays a broad cardioprotective role in different pathological conditions. Chaperone proteins, besides playing a role in protein folding, are also able to facilitate supramolecular complex formation and conformational changes due to activation/deactivation of signaling molecules. This role sets chaperone proteins as crucial regulators of intracellular signal transduction pathways. In particular Melusin activates AKT and ERK1/2 signaling, protects cardiomyocytes from apoptosis and induces a compensatory hypertrophic response in several pathological conditions. Therefore, selective delivery of the Melusin gene in heart via cardiotropic adenoviral associated virus serotype 9 (AAV9), may represent a new promising gene-therapy approach for different cardiac pathologies.

  5. Melusin Promotes a Protective Signal Transduction Cascade in Stressed Hearts.

    PubMed

    Sorge, Matteo; Brancaccio, Mara

    2016-01-01

    Melusin is a chaperone protein selectively expressed in heart and skeletal muscles. Melusin expression levels correlate with cardiac function in pre-clinical models and in human patients with aortic stenosis. Indeed, previous studies in several animal models indicated that Melusin plays a broad cardioprotective role in different pathological conditions. Chaperone proteins, besides playing a role in protein folding, are also able to facilitate supramolecular complex formation and conformational changes due to activation/deactivation of signaling molecules. This role sets chaperone proteins as crucial regulators of intracellular signal transduction pathways. In particular Melusin activates AKT and ERK1/2 signaling, protects cardiomyocytes from apoptosis and induces a compensatory hypertrophic response in several pathological conditions. Therefore, selective delivery of the Melusin gene in heart via cardiotropic adenoviral associated virus serotype 9 (AAV9), may represent a new promising gene-therapy approach for different cardiac pathologies. PMID:27672636

  6. BRET biosensors to study GPCR biology, pharmacology, and signal transduction.

    PubMed

    Salahpour, Ali; Espinoza, Stefano; Masri, Bernard; Lam, Vincent; Barak, Larry S; Gainetdinov, Raul R

    2012-01-01

    Bioluminescence resonance energy transfer (BRET)-based biosensors have been extensively used over the last decade to study protein-protein interactions and intracellular signal transduction in living cells. In this review, we discuss the various BRET biosensors that have been developed to investigate biology, pharmacology, and signaling of G protein-coupled receptors (GPCRs). GPCRs form two distinct types of multiprotein signal transduction complexes based upon their inclusion of G proteins or β-arrestins that can be differentially affected by drugs that exhibit functional selectivity toward G protein or β-arrestin signaling. BRET has been especially adept at illuminating the dynamics of protein-protein interactions between receptors, G proteins, β-arrestins, and their many binding partners in living cells; as well as measuring the formation and accumulation of second messengers following receptor activation. Specifically, we discuss in detail the application of BRET to study dopamine and trace amine receptors signaling, presenting examples of an exchange protein activated by cAMP biosensor to measure cAMP, β-arrestin biosensors to determine β-arrestin recruitment to the receptor, and dopamine D2 receptor and trace amine-associated receptor 1 biosensors to investigate heterodimerization between them. As the biochemical spectrum of BRET biosensors expands, the number of signaling pathways that can be measured will concomitantly increase. This will be particularly useful for the evaluation of functional selectivity in which the real-time BRET capability to measure distinct signaling modalities will dramatically shorten the time to characterize new generation of biased drugs. These emerging approaches will further expand the growing application of BRET in the screening for novel pharmacologically active compounds.

  7. Signal transduction of stress via ceramide.

    PubMed Central

    Mathias, S; Peña, L A; Kolesnick, R N

    1998-01-01

    The sphingomyelin (SM) pathway is a ubiquitous, evolutionarily conserved signalling system analogous to conventional systems such as the cAMP and phosphoinositide pathways. Ceramide, which serves as second messenger in this pathway, is generated from SM by the action of a neutral or acidic SMase, or by de novo synthesis co-ordinated through the enzyme ceramide synthase. A number of direct targets for ceramide action have now been identified, including ceramide-activated protein kinase, ceramide-activated protein phosphatase and protein kinase Czeta, which couple the SM pathway to well defined intracellular signalling cascades. The SM pathway induces differentiation, proliferation or growth arrest, depending on the cell type. Very often, however, the outcome of signalling through this pathway is apoptosis. Mammalian systems respond to diverse stresses with ceramide generation, and recent studies show that yeast manifest a form of this response. Thus ceramide signalling is an older stress response system than the caspase/apoptotic death pathway, and hence these two pathways must have become linked later in evolution. Signalling of the stress response through ceramide appears to play a role in the development of human diseases, including ischaemia/reperfusion injury, insulin resistance and diabetes, atherogenesis, septic shock and ovarian failure. Further, ceramide signalling mediates the therapeutic effects of chemotherapy and radiation in some cells. An understanding of the mechanisms by which ceramide regulates physiological and pathological events in specific cells may provide new targets for pharmacological intervention. PMID:9794783

  8. Pseudomonas fluorescens and Glomus mosseae trigger DMI3-dependent activation of genes related to a signal transduction pathway in roots of Medicago truncatula.

    PubMed

    Sanchez, Lisa; Weidmann, Stéphanie; Arnould, Christine; Bernard, Anne Rose; Gianinazzi, Silvio; Gianinazzi-Pearson, Vivienne

    2005-10-01

    Plant genes induced during early root colonization of Medicago truncatula Gaertn. J5 by a growth-promoting strain of Pseudomonas fluorescens (C7R12) have been identified by suppressive subtractive hybridization. Ten M. truncatula genes, coding proteins associated with a putative signal transduction pathway, showed an early and transient activation during initial interactions between M. truncatula and P. fluorescens, up to 8 d after root inoculation. Gene expression was not significantly enhanced, except for one gene, in P. fluorescens-inoculated roots of a Myc(-)Nod(-) genotype (TRV25) of M. truncatula mutated for the DMI3 (syn. MtSYM13) gene. This gene codes a Ca(2+) and calmodulin-dependent protein kinase, indicating a possible role of calcium in the cellular interactions between M. truncatula and P. fluorescens. When expression of the 10 plant genes was compared in early stages of root colonization by mycorrhizal and rhizobial microsymbionts, Glomus mosseae activated all 10 genes, whereas Sinorhizobium meliloti only activated one and inhibited four others. None of the genes responded to inoculation by either microsymbiont in roots of the TRV25 mutant. The similar response of the M. truncatula genes to P. fluorescens and G. mosseae points to common molecular pathways in the perception of the microbial signals by plant roots.

  9. Studying Signal Transduction in Single Dendritic Spines

    PubMed Central

    Yasuda, Ryohei

    2012-01-01

    Many forms of synaptic plasticity are triggered by biochemical signaling that occurs in small postsynaptic compartments called dendritic spines, each of which typically houses the postsynaptic terminal associated with a single glutamatergic synapse. Recent advances in optical techniques allow investigators to monitor biochemical signaling in single dendritic spines and thus reveal the signaling mechanisms that link synaptic activity and the induction of synaptic plasticity. This is mostly in the study of Ca2+-dependent forms of synaptic plasticity for which many of the steps between Ca2+ influx and changes to the synapse are now known. This article introduces the new techniques used to investigate signaling in single dendritic spines and the neurobiological insights that they have produced. PMID:22843821

  10. Association of toxicity of sorafenib and sunitinib for human keratinocytes with inhibition of signal transduction and activator of transcription 3 (STAT3).

    PubMed

    Yamamoto, Kazuhiro; Mizumoto, Atsushi; Nishimura, Kohji; Uda, Atsushi; Mukai, Akira; Yamashita, Kazuhiko; Kume, Manabu; Makimoto, Hiroo; Bito, Toshinori; Nishigori, Chikako; Nakagawa, Tsutomu; Hirano, Takeshi; Hirai, Midori

    2014-01-01

    Hand-foot skin reaction is a most common multi-kinase inhibitor-related adverse event. This study aimed to examine whether the toxicity of sorafenib and sunitinib for human keratinocytes was associated with inhibiting signal transduction and activator of transcription 3 (STAT3). We studied whether STAT3 activity affects sorafenib- and sunitinib-induced cell growth inhibition in HaCaT cells by WST-8 assay. Stattic enhanced the cell-growth inhibitory and apoptotic effects of sorafenib and sunitinib. HaCaT cells transfected with constitutively-active STAT3 (STAT3C) were resistant to the sorafenib- and sunitinib-induced cell growth inhibition. STAT3 activity decreased after short-term treatment with sorafenib and sunitinib in a dose-dependent manner and recovered after long-term treatment with sorafenib and sunitinib at low doses. Moreover, the expression of survivin and bcl-2 decreased after treatment with sorafenib and sunitinib was concomitant with variations in STAT3 activity. Sorafenib-induced STAT3 inhibition was mediated by regulation via MAPK pathways in HaCaT cells, while sunitinib-induced STAT3 inhibition was not. Thus, STAT3 activation mediating apoptosis suppressors may be a key factor in sorafenib and sunitinib-induced keratinocyte cytotoxicity. PMID:25013907

  11. Modelling protein functional domains in signal transduction using Maude

    NASA Technical Reports Server (NTRS)

    Sriram, M. G.

    2003-01-01

    Modelling of protein-protein interactions in signal transduction is receiving increased attention in computational biology. This paper describes recent research in the application of Maude, a symbolic language founded on rewriting logic, to the modelling of functional domains within signalling proteins. Protein functional domains (PFDs) are a critical focus of modern signal transduction research. In general, Maude models can simulate biological signalling networks and produce specific testable hypotheses at various levels of abstraction. Developing symbolic models of signalling proteins containing functional domains is important because of the potential to generate analyses of complex signalling networks based on structure-function relationships.

  12. Signal transduction in the footsteps of goethe and schiller.

    PubMed

    Friedrich, Karlheinz; Lindquist, Jonathan A; Entschladen, Frank; Serfling, Edgar; Thiel, Gerald; Kieser, Arnd; Giehl, Klaudia; Ehrhardt, Christina; Feller, Stephan M; Ullrich, Oliver; Schaper, Fred; Janssen, Ottmar; Hass, Ralf

    2009-02-04

    The historical town of Weimar in Thuringia, the "green heart of Germany" was the sphere of Goethe and Schiller, the two most famous representatives of German literature's classic era. Not yet entirely as influential as those two cultural icons, the Signal Transduction Society (STS) has nevertheless in the last decade established within the walls of Weimar an annual interdisciplinary Meeting on "Signal Transduction - Receptors, Mediators and Genes", which is well recognized as a most attractive opportunity to exchange results and ideas in the field.The 12th STS Meeting was held from October 28 to 31 and provided a state-of-the-art overview of various areas of signal transduction research in which progress is fast and discussion lively. This report is intended to share with the readers of CCS some highlights of the Meeting Workshops devoted to specific aspects of signal transduction.

  13. MAPK Cascades in Guard Cell Signal Transduction

    PubMed Central

    Lee, Yuree; Kim, Yun Ju; Kim, Myung-Hee; Kwak, June M.

    2016-01-01

    Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK) cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions. PMID:26904052

  14. MAPK Cascades in Guard Cell Signal Transduction.

    PubMed

    Lee, Yuree; Kim, Yun Ju; Kim, Myung-Hee; Kwak, June M

    2016-01-01

    Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK) cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions.

  15. MAPK Cascades in Guard Cell Signal Transduction.

    PubMed

    Lee, Yuree; Kim, Yun Ju; Kim, Myung-Hee; Kwak, June M

    2016-01-01

    Guard cells form stomata on the epidermis and continuously respond to endogenous and environmental stimuli to fine-tune the gas exchange and transpirational water loss, processes which involve mitogen-activated protein kinase (MAPK) cascades. MAPKs form three-tiered kinase cascades with MAPK kinases and MAPK kinase kinases, by which signals are transduced to the target proteins. MAPK cascade genes are highly conserved in all eukaryotes, and they play crucial roles in myriad developmental and physiological processes. MAPK cascades function during biotic and abiotic stress responses by linking extracellular signals received by receptors to cytosolic events and gene expression. In this review, we highlight recent findings and insights into MAPK-mediated guard cell signaling, including the specificity of MAPK cascades and the remaining questions. PMID:26904052

  16. Gene Expressions for Signal Transduction under Acidic Conditions

    PubMed Central

    Fukamachi, Toshihiko; Ikeda, Syunsuke; Wang, Xin; Saito, Hiromi; Tagawa, Masatoshi; Kobayashi, Hiroshi

    2013-01-01

    Although it is now well known that some diseased areas, such as cancer nests, inflammation loci, and infarction areas, are acidified, little is known about cellular signal transduction, gene expression, and cellular functions under acidic conditions. Our group showed that different signal proteins were activated under acidic conditions compared with those observed in a typical medium of around pH 7.4 that has been used until now. Investigations of gene expression under acidic conditions may be crucial to our understanding of signal transduction in acidic diseased areas. In this study, we investigated gene expression in mesothelioma cells cultured at an acidic pH using a DNA microarray technique. After 24 h culture at pH 6.7, expressions of 379 genes were increased more than twofold compared with those in cells cultured at pH 7.5. Genes encoding receptors, signal proteins including transcription factors, and cytokines including growth factors numbered 35, 32, and 17 among the 379 genes, respectively. Since the functions of 78 genes are unknown, it can be argued that cells may have other genes for signaling under acidic conditions. The expressions of 37 of the 379 genes were observed to increase after as little as 2 h. After 24 h culture at pH 6.7, expressions of 412 genes were repressed more than twofold compared with those in cells cultured at pH 7.5, and the 412 genes contained 35, 76, and 7 genes encoding receptors, signal proteins including transcription factors, and cytokines including growth factors, respectively. These results suggest that the signal pathways in acidic diseased areas are different, at least in part, from those examined with cells cultured at a pH of around 7.4. PMID:24705103

  17. Gravity perception and signal transduction in single cells

    NASA Astrophysics Data System (ADS)

    Block, I.; Wolke, A.; Briegleb, W.; Ivanova, K.

    Cellular signal processing in multi-, as well as in unicellular organisms, has to rely on fundamentally similar mechanisms. Free-living single cells often use the gravity vector for their spatial orientation (gravitaxis) and show distinct gravisensitivities. In this investigation the gravisensitive giant ameboid cell Physarum polycephalum (Myxomycetes, acellular slime molds) is used. Its gravitaxis and the modulation of its intrinsic rhythmic contraction activity by gravity was demonstrated in 180 °turn experiments and in simulated, as well as in actual, near-weightlessness studies (fast-rotating clinostat; Spacelab D1, IML-1). The stimulus perception was addressed in an IML-2 experiment, which provided information on the gravireceptor itself by the determination of the cell's acceleration-sensitivity threshold. Ground-based experiments designed to elucidate the subsequent steps in signal transduction leading to a motor response, suggest that an acceleration stimulus induces changes in the level of second messenger, adenosine 3',5'-cyclic monophosphate (cAMP), indicating also that the acceleration-stimulus signal transduction chain of Physarum uses an ubiquitous second messenger pathway.

  18. Comparative analyses of downstream signal transduction targets modulated after activation of the AT1 receptor by two β-arrestin-biased agonists.

    PubMed

    Santos, Geisa A; Duarte, Diego A; Parreiras-E-Silva, Lucas T; Teixeira, Felipe R; Silva-Rocha, Rafael; Oliveira, Eduardo B; Bouvier, Michel; Costa-Neto, Claudio M

    2015-01-01

    G protein-coupled receptors (GPCRs) are involved in essentially all physiological processes in mammals. The classical GPCR signal transduction mechanism occurs by coupling to G protein, but it has recently been demonstrated that interaction with β-arrestins leads to activation of pathways that are independent of the G protein pathway. Also, it has been reported that some ligands can preferentially activate one of these signaling pathways; being therefore called biased agonists for G protein or β-arrestin pathways. The angiotensin II (AngII) AT1 receptor is a prototype GPCR in the study of biased agonism due to the existence of well-known β-arrestin-biased agonists, such as [Sar(1), Ile(4), Ile(8)]-AngII (SII), and [Sar(1), D-Ala(8)]-AngII (TRV027). The aim of this study was to comparatively analyze the two above mentioned β-arrestin-biased agonists on downstream phosphorylation events and gene expression profiles. Our data reveal that activation of AT1 receptor by each ligand led to a diversity of activation profiles that is far broader than that expected from a simple dichotomy between "G protein-dependent" and "β-arrestin-dependent" signaling. We observed clusters of activation profiles common to AngII, SII, and TRV027, as well as downstream effector activation that are unique to AngII, SII, or TRV027. Analyses of β-arrestin conformational changes after AT1 receptor stimulation with SII or TRV027 suggests that the observed differences could account, at least partially, for the diversity of modulated targets observed. Our data reveal that, although the categorization "G protein-dependent" vs. "β-arrestin-dependent" signaling can be of pharmacological relevance, broader analyses of signaling pathways and downstream targets are necessary to generate an accurate activation profile for a given ligand. This may bring relevant information for drug development, as it may allow more refined comparison of drugs with similar mechanism of action and effects, but with

  19. Development and validation of a high-throughput cell-based screen to identify activators of a bacterial two-component signal transduction system.

    PubMed

    van Rensburg, Julia J; Fortney, Kate R; Chen, Lan; Krieger, Andrew J; Lima, Bruno P; Wolfe, Alan J; Katz, Barry P; Zhang, Zhong-Yin; Spinola, Stanley M

    2015-07-01

    CpxRA is a two-component signal transduction system (2CSTS) found in many drug-resistant Gram-negative bacteria. In response to periplasmic stress, CpxA autophosphorylates and donates a phosphoryl group to its cognate response regulator, CpxR. Phosphorylated CpxR (CpxR-P) upregulates genes involved in membrane repair and downregulates multiple genes that encode virulence factors, which are trafficked across the cell membrane. Mutants that constitutively activate CpxRA in Salmonella enterica serovar Typhimurium and Haemophilus ducreyi are avirulent in mice and humans, respectively. Thus, the activation of CpxRA has high potential as a novel antimicrobial/antivirulence strategy. Using a series of Escherichia coli strains containing a CpxR-P-responsive lacZ reporter and deletions in genes encoding CpxRA system components, we developed and validated a novel cell-based high-throughput screen (HTS) for CpxRA activators. A screen of 36,000 compounds yielded one hit compound that increased reporter activity in wild-type cells. This is the first report of a compound that activates, rather than inhibits, a 2CSTS. The activity profile of the compound against CpxRA pathway mutants in the presence of glucose suggested that the compound inhibits CpxA phosphatase activity. We confirmed that the compound induced the accumulation of CpxR-P in treated cells. Although the hit compound contained a nitro group, a derivative lacking this group retained activity in serum and had lower cytotoxicity than that of the initial hit. This HTS is amenable for the screening of larger libraries to find compounds that activate CpxRA by other mechanisms, and it could be adapted to find activators of other two-component systems.

  20. Activation of the Rcs Signal Transduction System Is Responsible for the Thermosensitive Growth Defect of an Escherichia coli Mutant Lacking Phosphatidylglycerol and Cardiolipin

    PubMed Central

    Shiba, Yasuhiro; Yokoyama, Yasuko; Aono, Yoshiko; Kiuchi, Takashi; Kusaka, Jin; Matsumoto, Kouji; Hara, Hiroshi

    2004-01-01

    The lethal effect of an Escherichia coli pgsA null mutation, which causes a complete lack of the major acidic phospholipids, phosphatidylglycerol and cardiolipin, is alleviated by a lack of the major outer membrane lipoprotein encoded by the lpp gene, but an lpp pgsA strain shows a thermosensitive growth defect. Using transposon mutagenesis, we found that this thermosensitivity was suppressed by disruption of the rcsC, rcsF, and yojN genes, which code for a sensor kinase, accessory positive factor, and phosphotransmitter, respectively, of the Rcs phosphorelay signal transduction system initially identified as regulating the capsular polysaccharide synthesis (cps) genes. Disruption of the rcsB gene coding for the response regulator of the system also suppressed the thermosensitivity, whereas disruption of cpsE did not. By monitoring the expression of a cpsB′-lac fusion, we showed that the Rcs system is activated in the pgsA mutant and is reverted to a wild-type level by the rcs mutations. These results indicate that envelope stress due to an acidic phospholipid deficiency activates the Rcs phosphorelay system and thereby causes the thermosensitive growth defect independent of the activation of capsule synthesis. PMID:15375134

  1. Signal Transduction in Histidine Kinases: Insights from New Structures

    PubMed Central

    Bhate, Manasi P.; Molnar, Kathleen S.; Goulian, Mark; DeGrado, William F.

    2015-01-01

    Histidine kinases (HKs) are major players in bacterial signaling. There has been an explosion of new HK crystal structures in the last five years. We globally analyze the structures of HKs to yield insights into the mechanisms by which signals are transmitted to and across protein structures in this family. We interpret known enzymological data in the context of new structural data to show how asymmetry across the dimer interface is a key feature of signal transduction in HKs, and discuss how different HK domains undergo asymmetric-to-symmetric transitions during signal transduction and catalysis. A thermodynamic framework for signaling that encompasses these various properties is presented and the consequences of weak thermodynamic coupling are discussed. The synthesis of observations from enzymology, structural biology, protein engineering and thermodynamics paves the way for a deeper molecular understanding of histidine kinase signal transduction. PMID:25982528

  2. Influence of Unweighting on Insulin Signal Transduction in Muscle

    NASA Technical Reports Server (NTRS)

    Tischler, Marc E.

    2002-01-01

    Unweighting of the juvenile soleus muscle is characterized by an increased binding capacity for insulin relative to muscle mass due to sparing of the receptors during atrophy. Although carbohydrate metabolism and protein degradation in the unweighted muscle develop increased sensitivity to insulin in vivo, protein synthesis in vivo and system A amino acid transport in vitro do not appear to develop such an enhanced response. The long-term goal is to identify the precise nature of this apparent resistance in the insulin signal transduction pathway and to consider how reduced weight-bearing may elicit this effect, by evaluating specific components of the insulin signalling pathway. Because the insulin-signalling pathway has components in common with the signal transduction pathway for insulin-like growth factor (IGF-1) and potentially other growth factors, the study could have important implications in the role of weight-bearing function on muscle growth and development. Since the insulin signalling pathway diverges following activation of insulin receptor tyrosine kinase, the immediate specific aims will be to study the receptor tyrosine kinase (IRTK) and those branches, which lead to phosphorylation of insulin receptor substrate-1 (IRS-1) and of Shc protein. To achieve these broader objectives, we will test in situ, by intramuscular injection, the responses of glucose transport, system A amino acid transport and protein synthesis to insulin analogues for which the receptor has either a weaker or much stronger binding affinity compared to insulin. Studies will include: (1) estimation of the ED(sub 50) for each analogue for these three processes; (2) the effect of duration (one to four days) of unweighting on the response of each process to all analogues tested; (3) the effect of unweighting and the analogues on IRTK activity; and (4) the comparative effects of unweighting and analogue binding on the tyrosine phosphorylation of IRTK, IRS-1, and Shc protein.

  3. Studying Chemoattractant Signal Transduction Dynamics in Dictyostelium by BRET.

    PubMed

    Islam, A F M Tariqul; Stepanski, Branden M; Charest, Pascale G

    2016-01-01

    Understanding the dynamics of chemoattractant signaling is key to our understanding of the mechanisms underlying the directed migration of cells, including that of neutrophils to sites of infections and of cancer cells during metastasis. A model frequently used for deciphering chemoattractant signal transduction is the social amoeba Dictyostelium discoideum. However, the methods available to quantitatively measure chemotactic signaling are limited. Here, we describe a protocol to quantitatively study chemoattractant signal transduction in Dictyostelium by monitoring protein-protein interactions and conformational changes using Bioluminescence Resonance Energy Transfer (BRET). PMID:27271894

  4. Mechanism and evolution of cytosolic Hedgehog signal transduction

    PubMed Central

    Wilson, Christopher W.; Chuang, Pao-Tien

    2010-01-01

    Hedgehog (Hh) signaling is required for embryonic patterning and postnatal physiology in invertebrates and vertebrates. With the revelation that the primary cilium is crucial for mammalian Hh signaling, the prevailing view that Hh signal transduction mechanisms are conserved across species has been challenged. However, more recent progress on elucidating the function of core Hh pathway cytosolic regulators in Drosophila, zebrafish and mice has confirmed that the essential logic of Hh transduction is similar between species. Here, we review Hh signaling events at the membrane and in the cytosol, and focus on parallel and divergent functions of cytosolic Hh regulators in Drosophila and mammals. PMID:20530542

  5. Activation of salicylic acid metabolism and signal transduction can enhance resistance to Fusarium wilt in banana (Musa acuminata L. AAA group, cv. Cavendish).

    PubMed

    Wang, Zhuo; Jia, Caihong; Li, Jingyang; Huang, Suzhen; Xu, Biyu; Jin, Zhiqiang

    2015-01-01

    Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. cubens (Foc) is the most serious disease that attacks banana plants. Salicylic acid (SA) can play a key role in plant-microbe interactions. Our study is the first to examine the role of SA in conferring resistance to Foc TR4 in banana (Musa acuminata L. AAA group, cv. Cavendish), which is the greatest commercial importance cultivar in Musa. We used quantitative real-time reverse polymerase chain reaction (qRT-PCR) to analyze the expression profiles of 45 genes related to SA biosynthesis and downstream signaling pathways in a susceptible banana cultivar (cv. Cavendish) and a resistant banana cultivar (cv. Nongke No. 1) inoculated with Foc TR4. The expression of genes involved in SA biosynthesis and downstream signaling pathways was suppressed in a susceptible cultivar and activated in a resistant cultivar. The SA levels in each treatment arm were measured using high-performance liquid chromatography. SA levels were decreased in the susceptible cultivar and increased in the resistant cultivar. Finally, we examined the contribution of exogenous SA to Foc TR4 resistance in susceptible banana plants. The expression of genes involved in SA biosynthesis and signal transduction pathways as well as SA levels were significantly increased. The results suggest that one reason for banana susceptibility to Foc TR4 is that expression of genes involved in SA biosynthesis and SA levels are suppressed and that the induced resistance observed in banana against Foc TR4 might be a case of salicylic acid-dependent systemic acquired resistance.

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

    PubMed Central

    Cheng, Yougan; Othmer, Hans

    2016-01-01

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

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

    PubMed

    Cheng, Yougan; Othmer, Hans

    2016-05-01

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

  8. Understanding the Impact of ErbB Activating Events and Signal Transduction on Antigen Processing and Presentation: MHC Expression as a Model

    PubMed Central

    Kersh, Anna E.; Sasaki, Maiko; Cooper, Lee A.; Kissick, Haydn T.; Pollack, Brian P.

    2016-01-01

    Advances in molecular pathology have changed the landscape of oncology. The ability to interrogate tissue samples for oncogene amplification, driver mutations, and other molecular alterations provides clinicians with an enormous level of detail about their patient’s cancer. In some cases, this information informs treatment decisions, especially those related to targeted anti-cancer therapies. However, in terms of immune-based therapies, it is less clear how to use such information. Likewise, despite studies demonstrating the pivotal role of neoantigens in predicting responsiveness to immune checkpoint blockade, it is not known if the expression of neoantigens impacts the response to targeted therapies despite a growing recognition of their diverse effects on immunity. To realize the promise of ‘personalized medicine’, it will be important to develop a more integrated understanding of the relationships between oncogenic events and processes governing anti-tumor immunity. One area of investigation to explore such relationships centers on defining how ErbB/HER activation and signal transduction influences antigen processing and presentation. PMID:27729860

  9. How ‘arm-twisting’ by the inducer triggers activation of the MalT transcription factor, a typical signal transduction ATPase with numerous domains (STAND)

    PubMed Central

    Danot, Olivier

    2015-01-01

    Signal transduction ATPases with numerous domains (STAND) get activated through inducer-dependent assembly into multimeric platforms. This switch relies on the conversion of their nucleotide-binding oligomerization domain (NOD) from a closed, ADP-bound form to an open, ATP-bound form. The NOD closed form is stabilized by contacts with the arm, a domain that connects the NOD to the inducer-binding domain called the sensor. How the inducer triggers NOD opening remains unclear. Here, I pinpointed the NOD-arm interface of the MalT STAND transcription factor, and I generated a MalT variant in which this interface can be covalently locked on demand, thereby trapping the NOD in the closed state. By characterizing this locked variant, I found that the inducer is recognized in two steps: it first binds to the sole sensor with low affinity, which then triggers the recruitment of the arm to form a high-affinity arm-sensor inducer-binding site. Strikingly, this high-affinity binding step was incompatible with arm-NOD contacts maintaining the NOD closed. Through this toggling between two mutually exclusive states reminiscent of a single-pole double-throw switch, the arm couples inducer binding to NOD opening, shown here to precede nucleotide exchange. This scenario likely holds for other STANDs like mammalian NLR innate immunity receptors. PMID:25740650

  10. Signal transduction in mammalian oocytes during fertilization.

    PubMed

    Machaty, Zoltan

    2016-01-01

    Mammalian embryo development begins when the fertilizing sperm triggers a series of elevations in the oocyte's intracellular free Ca(2+) concentration. The elevations are the result of repeated release and re-uptake of Ca(2+) stored in the smooth endoplasmic reticulum. Ca(2+) release is primarily mediated by the phosphoinositide signaling system of the oocyte. The system is stimulated when the sperm causes the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG); IP3 then binds its receptor on the surface of the endoplasmic reticulum that induces Ca(2+) release. The manner in which the sperm generates IP3, the Ca(2+) mobilizing second messenger, has been the subject of extensive research for a long time. The sperm factor hypothesis has eventually gained general acceptance, according to which it is a molecule from the sperm that diffuses into the ooplasm and stimulates the phosphoinositide cascade. Much evidence now indicates that the sperm-derived factor is phospholipase C-zeta (PLCζ) that cleaves PIP2 and generates IP3, eventually leading to oocyte activation. A recent addition to the candidate sperm factor list is the post-acrosomal sheath WW domain-binding protein (PAWP), whose role at fertilization is currently under debate. Ca(2+) influx across the plasma membrane is also important as, in the absence of extracellular Ca(2+), the oscillations run down prematurely. In pig oocytes, the influx that sustains the oscillations seems to be regulated by the filling status of the stores, whereas in the mouse other mechanisms might be involved. This work summarizes the current understanding of Ca(2+) signaling in mammalian oocytes.

  11. The interleukin-4 receptor: signal transduction by a hematopoietin receptor.

    PubMed

    Keegan, A D; Pierce, J H

    1994-02-01

    Over the last several years, the receptors for numerous cytokines have been molecularly characterized. Analysis of their amino acid sequences shows that some of these receptors bear certain motifs in their extracellular domains that define a family of receptors called the Hematopoietin receptor superfamily. Significant advances in characterizing the structure, function, and mechanisms of signal transduction have been made for several members of this family. The purpose of this review is to discuss the recent advances made for one of the family members, the interleukin (IL) 4 receptor. Other receptor systems have recently been reviewed elsewhere. The IL-4 receptor consists of, at the minimum, the cloned 140 kDa IL-4-binding chain with the potential for associating with other chains. The IL-4 receptor transduces its signal by activating a tyrosine kinase that phosphorylates cellular substrates, including the receptor itself, and the 170 kDa substrate called 4PS. Phosphorylated 4PS interacts with the SH2 domain of the enzyme PI-3'-kinase and increases its enzymatic activity. These early events in the IL-4 receptor initiated signaling pathway may trigger a series of signals that will ultimately lead to an IL-4 specific biologic outcome.

  12. Engineering aspects of enzymatic signal transduction: photoreceptors in the retina.

    PubMed Central

    Detwiler, P B; Ramanathan, S; Sengupta, A; Shraiman, B I

    2000-01-01

    Identifying the basic module of enzymatic amplification as an irreversible cycle of messenger activation/deactivation by a "push-pull" pair of opposing enzymes, we analyze it in terms of gain, bandwidth, noise, and power consumption. The enzymatic signal transduction cascade is viewed as an information channel, the design of which is governed by the statistical properties of the input and the noise and dynamic range constraints of the output. With the example of vertebrate phototransduction cascade we demonstrate that all of the relevant engineering parameters are controlled by enzyme concentrations and, from functional considerations, derive bounds on the required protein numbers. Conversely, the ability of enzymatic networks to change their response characteristics by varying only the abundance of different enzymes illustrates how functional diversity may be built from nearly conserved molecular components. PMID:11106590

  13. Analysis of intercellular signal transduction in the tumor microenvironment

    PubMed Central

    2013-01-01

    Background Recent cancer studies revealed, the interaction between pancreatic cancer cells and pancreatic stellate cells is of importance in the cancer progression. The activation of stellate cells is mediated by some growth factors and cytokines secreted by the cancer cells. In turn, the activated stellate cells will synthesize and secrete multiple growth factors to continuously stimulate the growth of surrounding cancer cells through paracrine pathways. The mechanism behind the evolution of stellate cells from quiescent state to a cancer-associated phenotype is still not well understood. Results To systematically investigate the interaction between cancer cells and stellate cells, we constructed a multicellular discrete value model, which is composed of several intracellular and intercellular signaling pathways that are frequently mutated in the pancreatic cancer, to study the cell cycle progression and angiogenesis. We, then, introduced and applied a formal verification technique, Symbolic Model Checking, to automatically analyze the cells' proliferation, angiogenesis and apoptosis in the proposed signal transduction model of tumor microenvironment. Conclusions Our studies predicted some important temporal logic properties and dynamic behaviors in the pancreatic cancer cells and stellate cells. The verification technique identified several signaling components, including the RAS, RAGE, AKT, IKK, DVL, RB and PTEN, whose mutation or loss of function can promote cell growth and inhibit apoptosis, some of which have been confirmed by existing experiments. Our formal studies demonstrated that, the bidirectional interaction between cancer cells and stellate cells could significantly increase cell proliferation, inhibit apoptosis, induce tumor angiogenesis, and promote cancer metastasis. PMID:24555417

  14. Activation of the PI3K/Akt signal transduction pathway and increased levels of insulin receptor in protein repair-deficient mice.

    PubMed

    Farrar, Christine; Houser, Carolyn R; Clarke, Steven

    2005-02-01

    Protein L-isoaspartate (D-aspartate) O-methyltransferase is an enzyme that catalyses the repair of isoaspartyl damage in proteins. Mice lacking this enzyme (Pcmt1-/- mice) have a progressive increase in brain size compared with wild-type mice (Pcmt1+/+ mice), a phenotype that can be associated with alterations in the PI3K/Akt signal transduction pathway. Here we show that components of this pathway, including Akt, GSK3beta and PDK-1, are more highly phosphorylated in the brains of Pcmt1-/- mice, particularly in cells of the hippocampus, in comparison with Pcmt1+/+ mice. Examination of upstream elements of this pathway in the hippocampus revealed that Pcmt1-/- mice have increased activation of insulin-like growth factor-I (IGF-I) receptor and/or insulin receptor. Western blot analysis revealed an approximate 200% increase in insulin receptor protein levels and an approximate 50% increase in IGF-I receptor protein levels in the hippocampus of Pcmt1-/- mice. Higher levels of the insulin receptor protein were also found in other regions of the adult brain and in whole tissue extracts of brain, liver, heart and testes of both juvenile and adult Pcmt1-/- mice. There were no significant differences in plasma insulin levels for adult Pcmt1-/- mice during glucose tolerance tests. However, they did show higher peak levels of blood glucose, suggesting a mild impairment in glucose tolerance. We propose that Pcmt1-/- mice have altered regulation of the insulin pathway, possibly as a compensatory response to altered glucose uptake or metabolism or as an adaptive response to a general accumulation of isoaspartyl protein damage in the brain and other tissues.

  15. PII Signal Transduction Proteins, Pivotal Players in Microbial Nitrogen Control

    PubMed Central

    Arcondéguy, Tania; Jack, Rachael; Merrick, Mike

    2001-01-01

    The PII family of signal transduction proteins are among the most widely distributed signal proteins in the bacterial world. First identified in 1969 as a component of the glutamine synthetase regulatory apparatus, PII proteins have since been recognized as playing a pivotal role in control of prokaryotic nitrogen metabolism. More recently, members of the family have been found in higher plants, where they also potentially play a role in nitrogen control. The PII proteins can function in the regulation of both gene transcription, by modulating the activity of regulatory proteins, and the catalytic activity of enzymes involved in nitrogen metabolism. There is also emerging evidence that they may regulate the activity of proteins required for transport of nitrogen compounds into the cell. In this review we discuss the history of the PII proteins, their structures and biochemistry, and their distribution and functions in prokaryotes. We survey data emerging from bacterial genome sequences and consider other likely or potential targets for control by PII proteins. PMID:11238986

  16. A respiratory chain controlled signal transduction cascade in the mitochondrial intermembrane space mediates hydrogen peroxide signaling.

    PubMed

    Patterson, Heide Christine; Gerbeth, Carolin; Thiru, Prathapan; Vögtle, Nora F; Knoll, Marko; Shahsafaei, Aliakbar; Samocha, Kaitlin E; Huang, Cher X; Harden, Mark Michael; Song, Rui; Chen, Cynthia; Kao, Jennifer; Shi, Jiahai; Salmon, Wendy; Shaul, Yoav D; Stokes, Matthew P; Silva, Jeffrey C; Bell, George W; MacArthur, Daniel G; Ruland, Jürgen; Meisinger, Chris; Lodish, Harvey F

    2015-10-20

    Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) govern cellular homeostasis by inducing signaling. H2O2 modulates the activity of phosphatases and many other signaling molecules through oxidation of critical cysteine residues, which led to the notion that initiation of ROS signaling is broad and nonspecific, and thus fundamentally distinct from other signaling pathways. Here, we report that H2O2 signaling bears hallmarks of a regular signal transduction cascade. It is controlled by hierarchical signaling events resulting in a focused response as the results place the mitochondrial respiratory chain upstream of tyrosine-protein kinase Lyn, Lyn upstream of tyrosine-protein kinase SYK (Syk), and Syk upstream of numerous targets involved in signaling, transcription, translation, metabolism, and cell cycle regulation. The active mediators of H2O2 signaling colocalize as H2O2 induces mitochondria-associated Lyn and Syk phosphorylation, and a pool of Lyn and Syk reside in the mitochondrial intermembrane space. Finally, the same intermediaries control the signaling response in tissues and species responsive to H2O2 as the respiratory chain, Lyn, and Syk were similarly required for H2O2 signaling in mouse B cells, fibroblasts, and chicken DT40 B cells. Consistent with a broad role, the Syk pathway is coexpressed across tissues, is of early metazoan origin, and displays evidence of evolutionary constraint in the human. These results suggest that H2O2 signaling is under control of a signal transduction pathway that links the respiratory chain to the mitochondrial intermembrane space-localized, ubiquitous, and ancient Syk pathway in hematopoietic and nonhematopoietic cells.

  17. A respiratory chain controlled signal transduction cascade in the mitochondrial intermembrane space mediates hydrogen peroxide signaling

    PubMed Central

    Patterson, Heide Christine; Gerbeth, Carolin; Thiru, Prathapan; Vögtle, Nora F.; Knoll, Marko; Shahsafaei, Aliakbar; Samocha, Kaitlin E.; Huang, Cher X.; Harden, Mark Michael; Song, Rui; Chen, Cynthia; Kao, Jennifer; Shi, Jiahai; Salmon, Wendy; Shaul, Yoav D.; Stokes, Matthew P.; Silva, Jeffrey C.; Bell, George W.; MacArthur, Daniel G.; Ruland, Jürgen; Meisinger, Chris; Lodish, Harvey F.

    2015-01-01

    Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) govern cellular homeostasis by inducing signaling. H2O2 modulates the activity of phosphatases and many other signaling molecules through oxidation of critical cysteine residues, which led to the notion that initiation of ROS signaling is broad and nonspecific, and thus fundamentally distinct from other signaling pathways. Here, we report that H2O2 signaling bears hallmarks of a regular signal transduction cascade. It is controlled by hierarchical signaling events resulting in a focused response as the results place the mitochondrial respiratory chain upstream of tyrosine-protein kinase Lyn, Lyn upstream of tyrosine-protein kinase SYK (Syk), and Syk upstream of numerous targets involved in signaling, transcription, translation, metabolism, and cell cycle regulation. The active mediators of H2O2 signaling colocalize as H2O2 induces mitochondria-associated Lyn and Syk phosphorylation, and a pool of Lyn and Syk reside in the mitochondrial intermembrane space. Finally, the same intermediaries control the signaling response in tissues and species responsive to H2O2 as the respiratory chain, Lyn, and Syk were similarly required for H2O2 signaling in mouse B cells, fibroblasts, and chicken DT40 B cells. Consistent with a broad role, the Syk pathway is coexpressed across tissues, is of early metazoan origin, and displays evidence of evolutionary constraint in the human. These results suggest that H2O2 signaling is under control of a signal transduction pathway that links the respiratory chain to the mitochondrial intermembrane space-localized, ubiquitous, and ancient Syk pathway in hematopoietic and nonhematopoietic cells. PMID:26438848

  18. Protein phosphorylation and its role in archaeal signal transduction.

    PubMed

    Esser, Dominik; Hoffmann, Lena; Pham, Trong Khoa; Bräsen, Christopher; Qiu, Wen; Wright, Phillip C; Albers, Sonja-Verena; Siebers, Bettina

    2016-09-01

    Reversible protein phosphorylation is the main mechanism of signal transduction that enables cells to rapidly respond to environmental changes by controlling the functional properties of proteins in response to external stimuli. However, whereas signal transduction is well studied in Eukaryotes and Bacteria, the knowledge in Archaea is still rather scarce. Archaea are special with regard to protein phosphorylation, due to the fact that the two best studied phyla, the Euryarchaeota and Crenarchaeaota, seem to exhibit fundamental differences in regulatory systems. Euryarchaeota (e.g. halophiles, methanogens, thermophiles), like Bacteria and Eukaryotes, rely on bacterial-type two-component signal transduction systems (phosphorylation on His and Asp), as well as on the protein phosphorylation on Ser, Thr and Tyr by Hanks-type protein kinases. Instead, Crenarchaeota (e.g. acidophiles and (hyper)thermophiles) only depend on Hanks-type protein phosphorylation. In this review, the current knowledge of reversible protein phosphorylation in Archaea is presented. It combines results from identified phosphoproteins, biochemical characterization of protein kinases and protein phosphatases as well as target enzymes and first insights into archaeal signal transduction by biochemical, genetic and polyomic studies.

  19. Protein phosphorylation and its role in archaeal signal transduction.

    PubMed

    Esser, Dominik; Hoffmann, Lena; Pham, Trong Khoa; Bräsen, Christopher; Qiu, Wen; Wright, Phillip C; Albers, Sonja-Verena; Siebers, Bettina

    2016-09-01

    Reversible protein phosphorylation is the main mechanism of signal transduction that enables cells to rapidly respond to environmental changes by controlling the functional properties of proteins in response to external stimuli. However, whereas signal transduction is well studied in Eukaryotes and Bacteria, the knowledge in Archaea is still rather scarce. Archaea are special with regard to protein phosphorylation, due to the fact that the two best studied phyla, the Euryarchaeota and Crenarchaeaota, seem to exhibit fundamental differences in regulatory systems. Euryarchaeota (e.g. halophiles, methanogens, thermophiles), like Bacteria and Eukaryotes, rely on bacterial-type two-component signal transduction systems (phosphorylation on His and Asp), as well as on the protein phosphorylation on Ser, Thr and Tyr by Hanks-type protein kinases. Instead, Crenarchaeota (e.g. acidophiles and (hyper)thermophiles) only depend on Hanks-type protein phosphorylation. In this review, the current knowledge of reversible protein phosphorylation in Archaea is presented. It combines results from identified phosphoproteins, biochemical characterization of protein kinases and protein phosphatases as well as target enzymes and first insights into archaeal signal transduction by biochemical, genetic and polyomic studies. PMID:27476079

  20. Protein phosphorylation and its role in archaeal signal transduction

    PubMed Central

    Esser, Dominik; Hoffmann, Lena; Pham, Trong Khoa; Bräsen, Christopher; Qiu, Wen; Wright, Phillip C.; Albers, Sonja-Verena; Siebers, Bettina

    2016-01-01

    Reversible protein phosphorylation is the main mechanism of signal transduction that enables cells to rapidly respond to environmental changes by controlling the functional properties of proteins in response to external stimuli. However, whereas signal transduction is well studied in Eukaryotes and Bacteria, the knowledge in Archaea is still rather scarce. Archaea are special with regard to protein phosphorylation, due to the fact that the two best studied phyla, the Euryarchaeota and Crenarchaeaota, seem to exhibit fundamental differences in regulatory systems. Euryarchaeota (e.g. halophiles, methanogens, thermophiles), like Bacteria and Eukaryotes, rely on bacterial-type two-component signal transduction systems (phosphorylation on His and Asp), as well as on the protein phosphorylation on Ser, Thr and Tyr by Hanks-type protein kinases. Instead, Crenarchaeota (e.g. acidophiles and (hyper)thermophiles) only depend on Hanks-type protein phosphorylation. In this review, the current knowledge of reversible protein phosphorylation in Archaea is presented. It combines results from identified phosphoproteins, biochemical characterization of protein kinases and protein phosphatases as well as target enzymes and first insights into archaeal signal transduction by biochemical, genetic and polyomic studies. PMID:27476079

  1. Signal transduction through the IL-4 and insulin receptor families.

    PubMed

    Wang, L M; Keegan, A; Frankel, M; Paul, W E; Pierce, J H

    1995-07-01

    Activation of tyrosine kinase-containing receptors and intracellular tyrosine kinases by ligand stimulation is known to be crucial for mediating initial and subsequent events involved in mitogenic signal transduction. Receptors for insulin and insulin-like growth factor 1 (IGF-1) contain cytoplasmic tyrosine kinase domains that undergo autophosphorylation upon ligand stimulation. Activation of these receptors also leads to pronounced and rapid tyrosine phosphorylation of insulin receptor substrate 1 (IRS-1) in cells of connective tissue origin. A related substrate, designated 4PS, is similarly phosphorylated by insulin and IGF-1 stimulation in many hematopoietic cell types. IRS-1 and 4PS possess a number of tyrosine phosphorylation sites that are within motifs that bind specific SH2-containing molecules known to be involved in mitogenic signaling such as PI-3 kinase, SHPTP-2 (Syp) and Grb-2. Thus, they appear to act as docking substrates for a variety of signaling molecules. The majority of hematopoietic cytokines bind to receptors that do not possess intrinsic kinase activity, and these receptors have been collectively termed as members of the hematopoietin receptor superfamily. Despite their lack of tyrosine kinase domains, stimulation of these receptors has been demonstrated to activate intracellular kinases leading to tyrosine phosphorylation of multiple substrates. Recent evidence has demonstrated that activation of different members of the Janus family of tyrosine kinases is involved in mediating tyrosine phosphorylation events by specific cytokines. Stimulation of the interleukin 4 (IL-4) receptor, a member of the hematopoietin receptor superfamily, is thought to result in activation of Jak1, Jak3, and/or Fes tyrosine kinases.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Signal transduction molecule patterns indicating potential glioblastoma therapy approaches

    PubMed Central

    Cruceru, Maria Linda; Enciu, Ana-Maria; Popa, Adrian Claudiu; Albulescu, Radu; Neagu, Monica; Tanase, Cristiana Pistol; Constantinescu, Stefan N

    2013-01-01

    Purpose The expression of an array of signaling molecules, along with the assessment of real-time cell proliferation, has been performed in U87 glioma cell line and in patients’ glioblastoma established cell cultures in order to provide a better understanding of cellular and molecular events involved in glioblastoma pathogenesis. Experimental therapy was performed using a phosphatidylinositol-3′-kinase (PI3K) inhibitor. Patients and methods xMAP technology was employed to assess expression levels of several signal transduction molecules and real-time xCELLigence platform for cell behavior. Results PI3K inhibition induced the most significant effects on global signaling pathways in patient-derived cell cultures, especially on members of the mitogen-activated protein-kinase family, P70S6 serine-threonine kinase, and cAMP response element-binding protein expression and further prevented tumor cell proliferation. Conclusion The PI3K pathway might be a prime target for glioblastoma treatment. PMID:24348050

  3. Resveratrol inhibits phosphorylation within the signal transduction and activator of transcription 3 signaling pathway by activating sirtuin 1 in SW1353 chondrosarcoma cells.

    PubMed

    Jin, Haidong; Chen, Hui; Yu, Kehe; Zhang, Jingdong; Li, Bin; Cai, Ningyu; Pan, Jun

    2016-09-01

    The present study assessed the mechanism by which resveratrol (Res) inhibits the growth of SW1353 chondrosarcoma cells and examined whether sirtuin 1 (Sirt1) activation affects phosphorylation within the signal transduction and activator of transcription 3 (STAT3) signaling pathway. The present study used SW1353 chondrosarcoma cells in the logarithmic phase of growth (control and treatment groups). The latter group was treated with Res at 25 and 50 µmol/l for 24 h, and cell viability, proliferation and apoptosis were analyzed using the cell counting kit‑8 assay, colony counting and Hoechst staining, respectively. The expression levels of caspase‑3, cleaved caspase‑3, B‑cell lymphoma‑2 (BCL‑2), BCL-2 associated X protein (Bax), STAT3 and phosphorylated (p‑)STAT3) were measured by Western blotting. SW1353 cells were transfected with small interfering (si)RNA targeting Sirt1 and the expression levels of Sirt1, STAT3 and p-STAT3 were assessed. Exposure of SW1353 cells to Res reduced cell viability in a dose‑dependent manner (P<0.01). Additionally, cell proliferation was significantly inhibited and the cell nuclei exhibited apoptotic characteristics. Cleaved caspase‑3, Sirt1 and Bax levels were upregulated. The expression levels of BCL‑2 and p‑STAT3 were downregulated. Additionally, the BCL‑2/Bax ratio was reduced compared with the control group. The total STAT3 level was unaffected. Res treatment activated Sirt1, however, in cells transfected with Sirt1‑siRNA, the ability of resveratrol to suppress p‑STAT3 expression was compromised. Overall, it was revealed that Res treatment induced apoptosis, inhibited proliferation and affected phosphorylation within the STAT3 signaling pathway by activating Sirt1 in SW1353 chondrosarcoma cells.

  4. Bacterial stimulus perception and signal transduction: response to osmotic stress.

    PubMed

    Krämer, Reinhard

    2010-08-01

    When exposed to osmotic stress from the environment, bacteria act to maintain cell turgor and hydration by responding both on the level of gene transcription and protein activity. Upon a sudden decrease in external osmolality, internal solutes are released by the action of membrane embedded mechanosensitive channels. In response to an osmotic upshift, the concentration of osmolytes in the cytoplasm is increased both by de novo synthesis and by active uptake. In order to coordinate these processes of osmoregulation, cells are equipped with systems and mechanisms of sensing physical stimuli correlated to changes in the external osmolality (osmosensing), with pathways to transduce these stimuli into useful signals which can be processed in the cell (signal transduction), and mechanisms of regulating proper responses in the cell to recover from the environmental stress and to maintain all necessary physiological functions (osmoregulation). These processes will be described by a number of representative examples, mainly of osmoreactive transport systems with a focus on available data of their molecular mechanism.

  5. NO, nitrotyrosine, and cyclic GMP in signal transduction

    NASA Technical Reports Server (NTRS)

    Hanafy, K. A.; Krumenacker, J. S.; Murad, F.

    2001-01-01

    Over the past 25 years, the role of nitric oxide (NO) in biology has evolved from being recognized as an environmental pollutant to an endogenously produced substance involved in cell communication and signal transduction. NO is produced by a family of enzymes called nitric oxide synthases (NOSs), which can be stimulated by a variety of factors that mediate responses to various stimuli. NO can initiate its biological effects through activation of the heterodimeric enzyme, soluble guanylyl cyclase (sGC), or through several other chemical reactions. Activation of sGC results in the production of 3',5'-cyclic guanosine monophosphate (cGMP), an intracellular second messenger signaling molecule, which can subsequently mediate such diverse physiological events such as vasodilatation and immunomodulation. Chemically reactive NO can affect physiological changes through modifications to cellular proteins, one of which is tyrosine nitration. The demonstration that NO is involved in so many biological pathways indicates the importance of this endogenously produced substance, and suggests that there is much more to be discovered about its role in biology in years to come.

  6. Intersubunit complementation of sugar signal transduction in VirA heterodimers and posttranslational regulation of VirA activity in Agrobacterium tumefaciens.

    PubMed

    Wise, Arlene A; Voinov, Luba; Binns, Andrew N

    2005-01-01

    The VirA/VirG two-component regulatory system of Agrobacterium tumefaciens regulates expression of the virulence (vir) genes that control the infection process leading to crown gall tumor disease on susceptible plants. VirA, a membrane-bound homodimer, initiates vir gene induction by communicating the presence of molecular signals found at the site of a plant wound through phosphorylation of VirG. Inducing signals include phenols, monosaccharides, and acidic pH. While sugars are not essential for gene induction, their presence greatly increases vir gene expression when levels of the essential phenolic signal are low. Reception of the sugar signal depends on a direct interaction between ChvE, a sugar-binding protein, and VirA. Here we show that the sugar signal received in the periplasmic region of one subunit within a VirA heterodimer can enhance the kinase function of the second subunit. However, sugar enhancement of vir gene expression was vector dependent. virA alleles expressed from pSa-derived vectors inhibited signal transduction by endogenous VirA. Inhibition was conditional, depending on the induction medium and the virA allele tested. Moreover, constitutive expression of virG overcame the inhibitory effect of some but not all virA alleles, suggesting that there may be more than one inhibitory mechanism. PMID:15601705

  7. Signal transduction and Th17 cell differentiation

    PubMed Central

    O’Shea, John J.; Steward-Tharp, Scott M.; Laurence, Arian; Watford, Wendy T.; Wei, Lai; Adamson, Adewole S.; Fan, Samuel

    2009-01-01

    The paradigm of effector T helper cell differentiation into either Th1 or Th2 lineages has been notably shaken by the discovery of a third lineage of cells that selectively produce interleukin (IL)-17. Characterization of this new subset, referred to as Th17, has provided exciting new insights into immunoregulation, host defense and the pathogenesis of autoimmune diseases. Additionally, the discovery of this T cell subset has offered a fresh look at such concepts as lineage commitment and terminal differentiation. The transcriptional regulatory events and epigenetic modifications that control these processes are diverse and complex, and despite the rapid pace at which data continues to accumulate, many questions remain to be answered. Here we review our current understanding of the signaling pathways, molecular interactions and transcriptional events that lead to Th17 differentiation and effector function, as well as the epigenetic modifications that accompany them. PMID:19379825

  8. Potentiating effect of an endocrine disruptor, paranonylphenol, on the generation of reactive oxygen species (ROS) in human venous blood -- association with the activation of signal transduction pathway.

    PubMed

    Okai, Yasuji; Sato, Eisuke F; Higashi-Okai, Kiyoka; Inoue, Masayasu

    2007-09-01

    effects on ROS generation in human blood with other inflammatory stimulants through the activation of signal transduction pathways such as protein kinase cascades.

  9. Soliton growth-signal transduction in topologically quantized T cells

    NASA Astrophysics Data System (ADS)

    Matsson, Leif

    1993-09-01

    A model for growth-signal transduction of the T cell and its growth factor, interleukin-2, is presented. It is obtained as a generalization of the usual rate equation and is founded on the observation that a definite number of receptor occupations must take place in order to promote transition to the S phase and subsequent DNA replication. The generalized rate equation is identified as the equation of motion of a Lagrangian field theory of Ginzburg-Landau (Goldstone) type. However it is not an ad hoc model but is a microscopic theory of the interaction of interleukin-2 and its receptor. The topological quantum number of the model is related to the observed definite number of receptor occupations required to elicit growth-signal transduction. Individual receptor quanta, up to this limit, are subjected to a type of Bose condensation. This collective excitation constitutes the growth signal in the form of a topological kink soliton which is then launched by the next potential receptor occupation that makes the interaction repulsive. The model provides a possible long-absent explanation of the triggering mechanism for growth-signal transduction by means of the ambivalent interaction, which switches sign after a definite number of receptor occupations. Moreover, it offers an explanation of how Nature screens out fractional signals in the growth-signal-transduction process of T cells. Although the model is derived for assumed point-like cells and certain other restrictions, the obtained dose-response curves are in striking agreement with proliferation data from studies of both the leukemic T cell line MLA-144 from gibbon ape and normal human T cells in, and without, the presence of monoclonal anti-Tac antibodies.

  10. VEGF-A isoforms program differential VEGFR2 signal transduction, trafficking and proteolysis

    PubMed Central

    Fearnley, Gareth W.; Smith, Gina A.; Abdul-Zani, Izma; Yuldasheva, Nadira; Mughal, Nadeem A.; Homer-Vanniasinkam, Shervanthi; Kearney, Mark T.; Zachary, Ian C.; Tomlinson, Darren C.; Harrison, Michael A.; Wheatcroft, Stephen B.; Ponnambalam, Sreenivasan

    2016-01-01

    ABSTRACT Vascular endothelial growth factor A (VEGF-A) binding to the receptor tyrosine kinase VEGFR2 triggers multiple signal transduction pathways, which regulate endothelial cell responses that control vascular development. Multiple isoforms of VEGF-A can elicit differential signal transduction and endothelial responses. However, it is unclear how such cellular responses are controlled by isoform-specific VEGF-A–VEGFR2 complexes. Increasingly, there is the realization that the membrane trafficking of receptor–ligand complexes influences signal transduction and protein turnover. By building on these concepts, our study shows for the first time that three different VEGF-A isoforms (VEGF-A165, VEGF-A121 and VEGF-A145) promote distinct patterns of VEGFR2 endocytosis for delivery into early endosomes. This differential VEGFR2 endocytosis and trafficking is linked to VEGF-A isoform-specific signal transduction events. Disruption of clathrin-dependent endocytosis blocked VEGF-A isoform-specific VEGFR2 activation, signal transduction and caused substantial depletion in membrane-bound VEGFR1 and VEGFR2 levels. Furthermore, such VEGF-A isoforms promoted differential patterns of VEGFR2 ubiquitylation, proteolysis and terminal degradation. Our study now provides novel insights into how different VEGF-A isoforms can bind the same receptor tyrosine kinase and elicit diverse cellular outcomes. PMID:27044325

  11. Catalase, but not MnSOD, inhibits glucose deprivation-activated ASK1-MEK-MAPK signal transduction pathway and prevents relocalization of Daxx: hydrogen peroxide as a major second messenger of metabolic oxidative stress.

    PubMed

    Song, Jae J; Lee, Yong J

    2003-10-01

    Overexpression of catalase, but not manganese superoxide dismutase (MnSOD), inhibited glucose deprivation-induced cytotoxicity and c-Jun N-terminal kinase 1 (JNK1) activation in human prostate adenocarcinoma DU-145 cells. Suppression of JNK1 activation by catalase overexpression resulted from inhibition of apoptosis signal-regulating kinase 1 (ASK1) activation by preventing dissociation of thioredoxin (TRX) from ASK1. Overexpression of catalase also inhibited relocalization of Daxx from the nucleus to the cytoplasm as well as association of Daxx with ASK1 during glucose deprivation. Taken together, hydrogen peroxide (H(2)O(2)) rather than superoxide anion (O(2) (*-)) acts as a second messenger of metabolic oxidative stress to activate the ASK1-MAPK/extracellular signal-regulated kinase (ERK) kinase (MEK)-mitogen-activated protein kinase (MAPK) signal transduction pathway.

  12. Bio-inspired signal transduction with heterogeneous networks of nanoscillators

    NASA Astrophysics Data System (ADS)

    Cervera, Javier; Manzanares, José A.; Mafé, Salvador

    2012-02-01

    Networks of single-electron transistors mimic some of the essential properties of neuron populations, because weak electrical signals trigger network oscillations with a frequency proportional to the input signal. Input potentials representing the pixel gray level of a grayscale image can then be converted into rhythms and the image can be recovered from these rhythms. Networks of non-identical nanoscillators complete the noisy transduction more reliably than identical ones. These results are important for signal processing schemes and could support recent studies suggesting that neuronal variability enhances the processing of biological information.

  13. The control of specificity in guard cell signal transduction

    PubMed Central

    Hetherington, A. M.

    1998-01-01

    Stomatal guard cells have proven to be an attractive system for dissecting the mechanisms of stimulus-response coupling in plants. In this review we focus on the intracellular signal transduction pathways by which extracellular signals bring about closure and opening of the stomatal pore. It is proposed that guard cell signal transduction pathways may be organized into functional arrays or signalling cassettes that contain elements common to a number of converging signalling pathways. The purpose of these signalling cassettes may be to funnel extracellular signals down onto the ion transporters that control the fluxes of ions that underlie stomatal movements. Evidence is emerging that specificity in guard cell signalling may be, in part, encoded in complex spatio-temporal patterns of increases in the concentration of cytosolic-free calcium ([Ca2+]cyt). It is suggested that oscillations in [Ca2+]cyt may generate calcium signatures that encode information concerning the stimulus type and strength. New evidence is presented that suggests that these calcium signatures may integrate information when many stimuli are present.

  14. Maxwell's demon in biochemical signal transduction with feedback loop

    NASA Astrophysics Data System (ADS)

    Ito, Sosuke; Sagawa, Takahiro

    2015-06-01

    Signal transduction in living cells is vital to maintain life itself, where information transfer in noisy environment plays a significant role. In a rather different context, the recent intensive research on `Maxwell's demon'--a feedback controller that utilizes information of individual molecules--have led to a unified theory of information and thermodynamics. Here we combine these two streams of research, and show that the second law of thermodynamics with information reveals the fundamental limit of the robustness of signal transduction against environmental fluctuations. Especially, we find that the degree of robustness is quantitatively characterized by an informational quantity called transfer entropy. Our information-thermodynamic approach is applicable to biological communication inside cells, in which there is no explicit channel coding in contrast to artificial communication. Our result could open up a novel biophysical approach to understand information processing in living systems on the basis of the fundamental information-thermodynamics link.

  15. Study of spatial signal transduction in bistable switches

    NASA Astrophysics Data System (ADS)

    Zhao, Qi; Yao, Cheng-Gui; Tang, Jun; Liu, Li-Wei

    2016-10-01

    Bistable switch modules are among the most important fundamental motifs in signal-transduction pathways. To better understand their spatial signal transduction, we model the diffusion process in the one-dimensional (1-D) domain. We find that when none of the elements diffuse, the response of the system exhibits a spatial switch-like property. However, when one of the elements is highly diffusible, the response of the system does not show any spatial switching behavior. Furthermore, we observe that the spatial responses of the system are more sensitive to the time constant of the switch when none of the elements are diffusible. Further, a slow loop keeps the system in the high steady state more positions than that in the fast loop. Finally, we consolidate our numerical results analytically by performing a mathematical method.

  16. Hypergravity signal transduction and gene expression in cultured mammalian cells

    NASA Technical Reports Server (NTRS)

    Kumei, Y.; Whitson, P. A.

    1994-01-01

    A number of studies have been conducted during space flight and with clinostats and centrifuges, suggesting that gravity effects the proliferation and differentiation of mammalian cells in vitro. However, little is known about the mechanisms by which mammalian cells respond to changes in gravitational stress. This paper summarizes studies designed to clarify the effects of hypergravity on the cultured human HeLa cells and to investigate the mechanism of hypergravity signal transduction in these cells.

  17. Signal transduction and information processing in mammalian taste buds

    PubMed Central

    2013-01-01

    The molecular machinery for chemosensory transduction in taste buds has received considerable attention within the last decade. Consequently, we now know a great deal about sweet, bitter, and umami taste mechanisms and are gaining ground rapidly on salty and sour transduction. Sweet, bitter, and umami tastes are transduced by G-protein-coupled receptors. Salty taste may be transduced by epithelial Na channels similar to those found in renal tissues. Sour transduction appears to be initiated by intracellular acidification acting on acid-sensitive membrane proteins. Once a taste signal is generated in a taste cell, the subsequent steps involve secretion of neurotransmitters, including ATP and serotonin. It is now recognized that the cells responding to sweet, bitter, and umami taste stimuli do not possess synapses and instead secrete the neurotransmitter ATP via a novel mechanism not involving conventional vesicular exocytosis. ATP is believed to excite primary sensory afferent fibers that convey gustatory signals to the brain. In contrast, taste cells that do have synapses release serotonin in response to gustatory stimulation. The postsynaptic targets of serotonin have not yet been identified. Finally, ATP secreted from receptor cells also acts on neighboring taste cells to stimulate their release of serotonin. This suggests that there is important information processing and signal coding taking place in the mammalian taste bud after gustatory stimulation. PMID:17468883

  18. State-time spectrum of signal transduction logic models

    NASA Astrophysics Data System (ADS)

    MacNamara, Aidan; Terfve, Camille; Henriques, David; Peñalver Bernabé, Beatriz; Saez-Rodriguez, Julio

    2012-08-01

    Despite the current wealth of high-throughput data, our understanding of signal transduction is still incomplete. Mathematical modeling can be a tool to gain an insight into such processes. Detailed biochemical modeling provides deep understanding, but does not scale well above relatively a few proteins. In contrast, logic modeling can be used where the biochemical knowledge of the system is sparse and, because it is parameter free (or, at most, uses relatively a few parameters), it scales well to large networks that can be derived by manual curation or retrieved from public databases. Here, we present an overview of logic modeling formalisms in the context of training logic models to data, and specifically the different approaches to modeling qualitative to quantitative data (state) and dynamics (time) of signal transduction. We use a toy model of signal transduction to illustrate how different logic formalisms (Boolean, fuzzy logic and differential equations) treat state and time. Different formalisms allow for different features of the data to be captured, at the cost of extra requirements in terms of computational power and data quality and quantity. Through this demonstration, the assumptions behind each formalism are discussed, as well as their advantages and disadvantages and possible future developments.

  19. Biomechanical Origins of Muscle Stem Cell Signal Transduction.

    PubMed

    Morrissey, James B; Cheng, Richard Y; Davoudi, Sadegh; Gilbert, Penney M

    2016-04-10

    Skeletal muscle, the most abundant and widespread tissue in the human body, contracts upon receiving electrochemical signals from the nervous system to support essential functions such as thermoregulation, limb movement, blinking, swallowing and breathing. Reconstruction of adult muscle tissue relies on a pool of mononucleate, resident muscle stem cells, known as "satellite cells", expressing the paired-box transcription factor Pax7 necessary for their specification during embryonic development and long-term maintenance during adult life. Satellite cells are located around the myofibres in a niche at the interface of the basal lamina and the host fibre plasma membrane (i.e., sarcolemma), at a very low frequency. Upon damage to the myofibres, quiescent satellite cells are activated and give rise to a population of transient amplifying myogenic progenitor cells, which eventually exit the cell cycle permanently and fuse to form new myofibres and regenerate the tissue. A subpopulation of satellite cells self-renew and repopulate the niche, poised to respond to future demands. Harnessing the potential of satellite cells relies on a complete understanding of the molecular mechanisms guiding their regulation in vivo. Over the past several decades, studies revealed many signal transduction pathways responsible for satellite cell fate decisions, but the niche cues driving the activation and silencing of these pathways are less clear. Here we explore the scintillating possibility that considering the dynamic changes in the biophysical properties of the skeletal muscle, namely stiffness, and the stretch and shear forces to which a myofibre can be subjected to may provide missing information necessary to gain a full understanding of satellite cell niche regulation. PMID:26004541

  20. Deciphering Parameter Sensitivity in the BvgAS Signal Transduction.

    PubMed

    Mapder, Tarunendu; Talukder, Srijeeta; Chattopadhyay, Sudip; Banik, Suman K

    2016-01-01

    To understand the switching of different phenotypic phases of Bordetella pertussis, we propose an optimized mathematical framework for signal transduction through BvgAS two-component system. The response of the network output to the sensory input has been demonstrated in steady state. An analysis in terms of local sensitivity amplification characterizes the nature of the molecular switch. The sensitivity analysis of the model parameters within the framework of various correlation coefficients helps to decipher the contribution of the modular structure in signal propagation. Once classified, the model parameters are tuned to generate the behavior of some novel strains using simulated annealing, a stochastic optimization technique.

  1. Deciphering Parameter Sensitivity in the BvgAS Signal Transduction

    PubMed Central

    Mapder, Tarunendu; Talukder, Srijeeta; Chattopadhyay, Sudip; Banik, Suman K.

    2016-01-01

    To understand the switching of different phenotypic phases of Bordetella pertussis, we propose an optimized mathematical framework for signal transduction through BvgAS two-component system. The response of the network output to the sensory input has been demonstrated in steady state. An analysis in terms of local sensitivity amplification characterizes the nature of the molecular switch. The sensitivity analysis of the model parameters within the framework of various correlation coefficients helps to decipher the contribution of the modular structure in signal propagation. Once classified, the model parameters are tuned to generate the behavior of some novel strains using simulated annealing, a stochastic optimization technique. PMID:26812153

  2. The dynamic control of signal transduction networks in cancer cells.

    PubMed

    Kolch, Walter; Halasz, Melinda; Granovskaya, Marina; Kholodenko, Boris N

    2015-09-01

    Cancer is often considered a genetic disease. However, much of the enormous plasticity of cancer cells to evolve different phenotypes, to adapt to challenging microenvironments and to withstand therapeutic assaults is encoded by the structure and spatiotemporal dynamics of signal transduction networks. In this Review, we discuss recent concepts concerning how the rich signalling dynamics afforded by these networks are regulated and how they impinge on cancer cell proliferation, survival, invasiveness and drug resistance. Understanding this dynamic circuitry by mathematical modelling could pave the way to new therapeutic approaches and personalized treatments.

  3. Roles of lipid turnover in transmembrane signal transduction.

    PubMed

    Ganong, B R

    1991-11-01

    Cells of higher organisms respond to external stimuli with a cascade of intracellular biochemical events initiated by binding of a hormone, growth factor, or neurotransmitter to a specific cell surface receptor. Previously well-characterized signal transduction pathways involve cyclic nucleotides as intracellular second messengers. Over the past decade, increasing attention has been focused on other signaling pathways in which membrane lipids serve as second messengers or their precursors. This review describes current understanding of these pathways and points to recent discoveries likely to open new frontiers in the coming decade.

  4. Changes in gene expression and signal transduction in microgravity

    NASA Technical Reports Server (NTRS)

    Hughes-Fulford, M.

    2001-01-01

    Studies from space flights over the past three decades have demonstrated that basic physiological changes occur in humans during space flight. These changes include cephalic fluid shifts, loss of fluid and electrolytes, loss of muscle mass, space motion sickness, anemia, reduced immune response, and loss of calcium and mineralized bone. The cause of most of these manifestations is not known and until recently, the general approach was to investigate general systemic changes, not basic cellular responses to microgravity. This laboratory has recently studied gene growth and activation of normal osteoblasts (MC3T3-El) during spaceflight. Osteoblast cells were grown on glass coverslips and loaded in the Biorack plunger boxes. The osteoblasts were launched in a serum deprived state, activated in microgravity and collected in microgravity. The osteoblasts were examined for changes in gene expression and signal transduction. Approximately one day after growth activation significant changes were observed in gene expression in 0-G flight samples. Immediate early growth genes/growth factors cox-2, c-myc, bcl2, TGF beta1, bFGF and PCNA showed a significant diminished mRNA induction in microgravity FCS activated cells when compared to ground and 1-G flight controls. Cox-1 was not detected in any of the samples. There were no significant differences in the expression of reference gene mRNA between the ground, 0-G and 1-G samples. The data suggest that quiescent osteoblasts are slower to enter the cell cycle in microgravity and that the lack of gravity itself may be a significant factor in bone loss in spaceflight. Preliminary data from our STS 76 flight experiment support our hypothesis that a basic biological response occurs at the tissue, cellular, and molecular level in 0-G. Here we examine ground-based and space flown data to help us understand the mechanism of bone loss in microgravity.

  5. Mechanistic Insights in Ethylene Perception and Signal Transduction1

    PubMed Central

    Ju, Chuanli; Chang, Caren

    2015-01-01

    The gaseous hormone ethylene profoundly affects plant growth, development, and stress responses. Ethylene perception occurs at the endoplasmic reticulum membrane, and signal transduction leads to a transcriptional cascade that initiates diverse responses, often in conjunction with other signals. Recent findings provide a more complete picture of the components and mechanisms in ethylene signaling, now rendering a more dynamic view of this conserved pathway. This includes newly identified protein-protein interactions at the endoplasmic reticulum membrane, as well as the major discoveries that the central regulator ETHYLENE INSENSITIVE2 (EIN2) is the long-sought phosphorylation substrate for the CONSTITUTIVE RESPONSE1 protein kinase, and that cleavage of EIN2 transmits the signal to the nucleus. In the nucleus, hundreds of potential gene targets of the EIN3 master transcription factor have been identified and found to be induced in transcriptional waves, and transcriptional coregulation has been shown to be a mechanism of ethylene cross talk. PMID:26246449

  6. Signal Transduction and Intracellular Trafficking by the Interleukin 36 Receptor*

    PubMed Central

    Saha, Siddhartha S.; Singh, Divyendu; Raymond, Ernest L.; Ganesan, Rajkumar; Caviness, Gary; Grimaldi, Christine; Woska, Joseph R.; Mennerich, Detlev; Brown, Su-Ellen; Mbow, M. Lamine; Kao, C. Cheng

    2015-01-01

    Improper signaling of the IL-36 receptor (IL-36R), a member of the IL-1 receptor family, has been associated with various inflammation-associated diseases. However, the requirements for IL-36R signal transduction remain poorly characterized. This work seeks to define the requirements for IL-36R signaling and intracellular trafficking. In the absence of cognate agonists, IL-36R was endocytosed and recycled to the plasma membrane. In the presence of IL-36, IL-36R increased accumulation in LAMP1+ lysosomes. Endocytosis predominantly used a clathrin-mediated pathway, and the accumulation of the IL-36R in lysosomes did not result in increased receptor turnover. The ubiquitin-binding Tollip protein contributed to IL-36R signaling and increased the accumulation of both subunits of the IL-36R. PMID:26269592

  7. Mechanistic Insights in Ethylene Perception and Signal Transduction.

    PubMed

    Ju, Chuanli; Chang, Caren

    2015-09-01

    The gaseous hormone ethylene profoundly affects plant growth, development, and stress responses. Ethylene perception occurs at the endoplasmic reticulum membrane, and signal transduction leads to a transcriptional cascade that initiates diverse responses, often in conjunction with other signals. Recent findings provide a more complete picture of the components and mechanisms in ethylene signaling, now rendering a more dynamic view of this conserved pathway. This includes newly identified protein-protein interactions at the endoplasmic reticulum membrane, as well as the major discoveries that the central regulator ETHYLENE INSENSITIVE2 (EIN2) is the long-sought phosphorylation substrate for the CONSTITUTIVE RESPONSE1 protein kinase, and that cleavage of EIN2 transmits the signal to the nucleus. In the nucleus, hundreds of potential gene targets of the EIN3 master transcription factor have been identified and found to be induced in transcriptional waves, and transcriptional coregulation has been shown to be a mechanism of ethylene cross talk.

  8. Reduced modeling of signal transduction – a modular approach

    PubMed Central

    Koschorreck, Markus; Conzelmann, Holger; Ebert, Sybille; Ederer, Michael; Gilles, Ernst Dieter

    2007-01-01

    Background Combinatorial complexity is a challenging problem in detailed and mechanistic mathematical modeling of signal transduction. This subject has been discussed intensively and a lot of progress has been made within the last few years. A software tool (BioNetGen) was developed which allows an automatic rule-based set-up of mechanistic model equations. In many cases these models can be reduced by an exact domain-oriented lumping technique. However, the resulting models can still consist of a very large number of differential equations. Results We introduce a new reduction technique, which allows building modularized and highly reduced models. Compared to existing approaches further reduction of signal transduction networks is possible. The method also provides a new modularization criterion, which allows to dissect the model into smaller modules that are called layers and can be modeled independently. Hallmarks of the approach are conservation relations within each layer and connection of layers by signal flows instead of mass flows. The reduced model can be formulated directly without previous generation of detailed model equations. It can be understood and interpreted intuitively, as model variables are macroscopic quantities that are converted by rates following simple kinetics. The proposed technique is applicable without using complex mathematical tools and even without detailed knowledge of the mathematical background. However, we provide a detailed mathematical analysis to show performance and limitations of the method. For physiologically relevant parameter domains the transient as well as the stationary errors caused by the reduction are negligible. Conclusion The new layer based reduced modeling method allows building modularized and strongly reduced models of signal transduction networks. Reduced model equations can be directly formulated and are intuitively interpretable. Additionally, the method provides very good approximations especially for

  9. Abscisic acid perception and signaling transduction in strawberry

    PubMed Central

    Li, Chunli; Jia, Haifeng; Chai, Yemao; Shen, Yuanyue

    2011-01-01

    On basis of fruit differential respiration and ethylene effects, climacteric and non-climacteric fruits have been classically defined. Over the past decades, the molecular mechanisms of climacteric fruit ripening were abundantly described and found to focus on ethylene perception and signaling transduction. In contrast, until our most recent breakthroughs, much progress has been made toward understanding the signaling perception and transduction mechanisms for abscisic acid (ABA) in strawberry, a model for non-climacteric fruit ripening. Our reports not only have provided several lines of strong evidences for ABA-regulated ripening of strawberry fruit, but also have demonstrated that homology proteins of Arabidopsis ABA receptors, including PYR/PYL/RCAR and ABAR/CHLH, act as positive regulators of ripening in response to ABA. These receptors also trigger a set of ABA downstream signaling components, and determine significant changes in the expression levels of both sugar and pigment metabolism-related genes that are closely associated with ripening. Soluble sugars, especially sucrose, may act as a signal molecular to trigger ABA accumulation through an enzymatic action of 9-cis-epoxycarotenoid dioxygenase 1 (FaNCED1). This mini-review offers an overview of these processes and also outlines the possible, molecular mechanisms for ABA in the regulation of strawberry fruit ripening through the ABA receptors. PMID:22095148

  10. Analysis and logical modeling of biological signaling transduction networks

    NASA Astrophysics Data System (ADS)

    Sun, Zhongyao

    The study of network theory and its application span across a multitude of seemingly disparate fields of science and technology: computer science, biology, social science, linguistics, etc. It is the intrinsic similarities embedded in the entities and the way they interact with one another in these systems that link them together. In this dissertation, I present from both the aspect of theoretical analysis and the aspect of application three projects, which primarily focus on signal transduction networks in biology. In these projects, I assembled a network model through extensively perusing literature, performed model-based simulations and validation, analyzed network topology, and proposed a novel network measure. The application of network modeling to the system of stomatal opening in plants revealed a fundamental question about the process that has been left unanswered in decades. The novel measure of the redundancy of signal transduction networks with Boolean dynamics by calculating its maximum node-independent elementary signaling mode set accurately predicts the effect of single node knockout in such signaling processes. The three projects as an organic whole advance the understanding of a real system as well as the behavior of such network models, giving me an opportunity to take a glimpse at the dazzling facets of the immense world of network science.

  11. Systematic Prediction of Scaffold Proteins Reveals New Design Principles in Scaffold-Mediated Signal Transduction

    PubMed Central

    Hu, Jianfei; Neiswinger, Johnathan; Zhang, Jin; Zhu, Heng; Qian, Jiang

    2015-01-01

    Scaffold proteins play a crucial role in facilitating signal transduction in eukaryotes by bringing together multiple signaling components. In this study, we performed a systematic analysis of scaffold proteins in signal transduction by integrating protein-protein interaction and kinase-substrate relationship networks. We predicted 212 scaffold proteins that are involved in 605 distinct signaling pathways. The computational prediction was validated using a protein microarray-based approach. The predicted scaffold proteins showed several interesting characteristics, as we expected from the functionality of scaffold proteins. We found that the scaffold proteins are likely to interact with each other, which is consistent with previous finding that scaffold proteins tend to form homodimers and heterodimers. Interestingly, a single scaffold protein can be involved in multiple signaling pathways by interacting with other scaffold protein partners. Furthermore, we propose two possible regulatory mechanisms by which the activity of scaffold proteins is coordinated with their associated pathways through phosphorylation process. PMID:26393507

  12. Systematic Prediction of Scaffold Proteins Reveals New Design Principles in Scaffold-Mediated Signal Transduction.

    PubMed

    Hu, Jianfei; Neiswinger, Johnathan; Zhang, Jin; Zhu, Heng; Qian, Jiang

    2015-01-01

    Scaffold proteins play a crucial role in facilitating signal transduction in eukaryotes by bringing together multiple signaling components. In this study, we performed a systematic analysis of scaffold proteins in signal transduction by integrating protein-protein interaction and kinase-substrate relationship networks. We predicted 212 scaffold proteins that are involved in 605 distinct signaling pathways. The computational prediction was validated using a protein microarray-based approach. The predicted scaffold proteins showed several interesting characteristics, as we expected from the functionality of scaffold proteins. We found that the scaffold proteins are likely to interact with each other, which is consistent with previous finding that scaffold proteins tend to form homodimers and heterodimers. Interestingly, a single scaffold protein can be involved in multiple signaling pathways by interacting with other scaffold protein partners. Furthermore, we propose two possible regulatory mechanisms by which the activity of scaffold proteins is coordinated with their associated pathways through phosphorylation process.

  13. The MiST2 database: a comprehensive genomics resource on microbial signal transduction

    PubMed Central

    Ulrich, Luke E.; Zhulin, Igor B.

    2010-01-01

    The MiST2 database (http://mistdb.com) identifies and catalogs the repertoire of signal transduction proteins in microbial genomes. Signal transduction systems regulate the majority of cellular activities including the metabolism, development, host-recognition, biofilm production, virulence, and antibiotic resistance of human pathogens. Thus, knowledge of the proteins and interactions that comprise these communication networks is an essential component to furthering biomedical discovery. These are identified by searching protein sequences for specific domain profiles that implicate a protein in signal transduction. Compared to the previous version of the database, MiST2 contains a host of new features and improvements including the following: draft genomes; extracytoplasmic function (ECF) sigma factor protein identification; enhanced classification of signaling proteins; novel, high-quality domain models for identifying histidine kinases and response regulators; neighboring two-component genes; gene cart; better search capabilities; enhanced taxonomy browser; advanced genome browser; and a modern, biologist-friendly web interface. MiST2 currently contains 966 complete and 157 draft bacterial and archaeal genomes, which collectively contain more than 245 000 signal transduction proteins. The majority (66%) of these are one-component systems, followed by two-component proteins (26%), chemotaxis (6%), and finally ECF factors (2%). PMID:19900966

  14. pathFinder: a static network analysis tool for pharmacological analysis of signal transduction pathways.

    PubMed

    Samal, Babru B; Eiden, Lee E

    2008-01-01

    The study of signal transduction is becoming a de facto part of the analysis of gene expression and protein profiling techniques. Many online tools are used to cluster genes in various ways or to assign gene products to signal transduction pathways. Among these, pathFinder is a unique tool that can find signal transduction pathways between first, second, or nth messengers and their targets within the cell. pathFinder can identify qualitatively all possible signal transduction pathways connecting any starting component and target within a database of two-component pathways (directional dyads). One or more intermediate pathway components can be excluded to simulate the use of pharmacological inhibitors or genetic deletion (knockout). Missing elements in a pathway connecting the activator or initiator and target can also be inferred from a null pathway result. The value of this static network analysis tool is illustrated by the predication from pathFinder analysis of a novel cyclic AMP-dependent, protein kinase A-independent signaling pathway in neuroendocrine cells, which has been experimentally confirmed.

  15. Ion channels and the transduction of light signals

    NASA Technical Reports Server (NTRS)

    Spalding, E. P.; Evans, M. L. (Principal Investigator)

    2000-01-01

    Studies of biological light-sensing mechanisms are revealing important roles for ion channels. Photosensory transduction in plants is no exception. In this article, the evidence that ion channels perform such signal-transducing functions in the complex array of mechanisms that bring about plant photomorphogenesis will be reviewed and discussed. The examples selected for discussion range from light-gradient detection in unicellular algae to the photocontrol of stem growth in Arabidopsis. Also included is some discussion of the technical aspects of studies that combine electrophysiology and photobiology.

  16. Calcium specificity signaling mechanisms in abscisic acid signal transduction in Arabidopsis guard cells

    PubMed Central

    Brandt, Benjamin; Munemasa, Shintaro; Wang, Cun; Nguyen, Desiree; Yong, Taiming; Yang, Paul G; Poretsky, Elly; Belknap, Thomas F; Waadt, Rainer; Alemán, Fernando; Schroeder, Julian I

    2015-01-01

    A central question is how specificity in cellular responses to the eukaryotic second messenger Ca2+ is achieved. Plant guard cells, that form stomatal pores for gas exchange, provide a powerful system for in depth investigation of Ca2+-signaling specificity in plants. In intact guard cells, abscisic acid (ABA) enhances (primes) the Ca2+-sensitivity of downstream signaling events that result in activation of S-type anion channels during stomatal closure, providing a specificity mechanism in Ca2+-signaling. However, the underlying genetic and biochemical mechanisms remain unknown. Here we show impairment of ABA signal transduction in stomata of calcium-dependent protein kinase quadruple mutant plants. Interestingly, protein phosphatase 2Cs prevent non-specific Ca2+-signaling. Moreover, we demonstrate an unexpected interdependence of the Ca2+-dependent and Ca2+-independent ABA-signaling branches and the in planta requirement of simultaneous phosphorylation at two key phosphorylation sites in SLAC1. We identify novel mechanisms ensuring specificity and robustness within stomatal Ca2+-signaling on a cellular, genetic, and biochemical level. DOI: http://dx.doi.org/10.7554/eLife.03599.001 PMID:26192964

  17. Calcium specificity signaling mechanisms in abscisic acid signal transduction in Arabidopsis guard cells.

    PubMed

    Brandt, Benjamin; Munemasa, Shintaro; Wang, Cun; Nguyen, Desiree; Yong, Taiming; Yang, Paul G; Poretsky, Elly; Belknap, Thomas F; Waadt, Rainer; Alemán, Fernando; Schroeder, Julian I

    2015-07-20

    A central question is how specificity in cellular responses to the eukaryotic second messenger Ca(2+) is achieved. Plant guard cells, that form stomatal pores for gas exchange, provide a powerful system for in depth investigation of Ca(2+)-signaling specificity in plants. In intact guard cells, abscisic acid (ABA) enhances (primes) the Ca(2+)-sensitivity of downstream signaling events that result in activation of S-type anion channels during stomatal closure, providing a specificity mechanism in Ca(2+)-signaling. However, the underlying genetic and biochemical mechanisms remain unknown. Here we show impairment of ABA signal transduction in stomata of calcium-dependent protein kinase quadruple mutant plants. Interestingly, protein phosphatase 2Cs prevent non-specific Ca(2+)-signaling. Moreover, we demonstrate an unexpected interdependence of the Ca(2+)-dependent and Ca(2+)-independent ABA-signaling branches and the in planta requirement of simultaneous phosphorylation at two key phosphorylation sites in SLAC1. We identify novel mechanisms ensuring specificity and robustness within stomatal Ca(2+)-signaling on a cellular, genetic, and biochemical level.

  18. Genetic analysis of gravity signal transduction in roots

    NASA Astrophysics Data System (ADS)

    Masson, Patrick; Strohm, Allison; Baldwin, Katherine

    To grow downward into the soil, roots use gravity as a guide. Specialized cells, named stato-cytes, enable this directional growth response by perceiving gravity. Located in the columella region of the cap, these cells sense a reorientation of the root within the gravity field through the sedimentation of, and/or tension/pressure exerted by, dense amyloplasts. This process trig-gers a gravity signal transduction pathway that leads to a fast alkalinization of the cytoplasm and a change in the distribution of the plasma membrane-associated auxin-efflux carrier PIN3. The latter protein is uniformly distributed within the plasma membrane on all sides of the cell in vertically oriented roots. However, it quickly accumulates at the bottom side upon gravis-timulation. This process correlates with a preferential transport of auxin to the bottom side of the root cap, resulting in a lateral gradient across the tip. This gradient is then transported to the elongation zone where it promotes differential cellular elongation, resulting in downward curvature. We isolated mutations that affect gravity signal transduction at a step that pre-cedes cytoplasmic alkalinization and/or PIN3 relocalization and lateral auxin transport across the cap. arg1 and arl2 mutations identify a common genetic pathway that is needed for all three gravity-induced processes in the cap statocytes, indicating these genes function early in the pathway. On the other hand, adk1 affects gravity-induced PIN3 relocalization and lateral auxin transport, but it does not interfere with cytoplasmic alkalinization. ARG1 and ARL2 encode J-domain proteins that are associated with membranes of the vesicular trafficking path-way whereas ADK1 encodes adenosine kinase, an enzyme that converts adenosine derived from nucleic acid metabolism and the AdoMet cycle into AMP, thereby alleviating feedback inhibi-tion of this important methyl-donor cycle. Because mutations in ARG1 (and ARL2) do not completely eliminate

  19. Perspective: Adhesion Mediated Signal Transduction in Bacterial Pathogens.

    PubMed

    Moorthy, Sudha; Keklak, Julia; Klein, Eric A

    2016-01-01

    During the infection process, pathogenic bacteria undergo large-scale transcriptional changes to promote virulence and increase intrahost survival. While much of this reprogramming occurs in response to changes in chemical environment, such as nutrient availability and pH, there is increasing evidence that adhesion to host-tissue can also trigger signal transduction pathways resulting in differential gene expression. Determining the molecular mechanisms of adhesion-mediated signaling requires disentangling the contributions of chemical and mechanical stimuli. Here we highlight recent work demonstrating that surface attachment drives a transcriptional response in bacterial pathogens, including uropathogenic Escherichia coli (E. coli), and discuss the complexity of experimental design when dissecting the specific role of adhesion-mediated signaling during infection.

  20. Molecular Mechanisms of Two-Component Signal Transduction.

    PubMed

    Zschiedrich, Christopher P; Keidel, Victoria; Szurmant, Hendrik

    2016-09-25

    Two-component systems (TCS) comprising sensor histidine kinases and response regulator proteins are among the most important players in bacterial and archaeal signal transduction and also occur in reduced numbers in some eukaryotic organisms. Given their importance to cellular survival, virulence, and cellular development, these systems are among the most scrutinized bacterial proteins. In the recent years, a flurry of bioinformatics, genetic, biochemical, and structural studies have provided detailed insights into many molecular mechanisms that underlie the detection of signals and the generation of the appropriate response by TCS. Importantly, it has become clear that there is significant diversity in the mechanisms employed by individual systems. This review discusses the current knowledge on common themes and divergences from the paradigm of TCS signaling. An emphasis is on the information gained by a flurry of recent structural and bioinformatics studies.

  1. Perspective: Adhesion Mediated Signal Transduction in Bacterial Pathogens

    PubMed Central

    Moorthy, Sudha; Keklak, Julia; Klein, Eric A.

    2016-01-01

    During the infection process, pathogenic bacteria undergo large-scale transcriptional changes to promote virulence and increase intrahost survival. While much of this reprogramming occurs in response to changes in chemical environment, such as nutrient availability and pH, there is increasing evidence that adhesion to host-tissue can also trigger signal transduction pathways resulting in differential gene expression. Determining the molecular mechanisms of adhesion-mediated signaling requires disentangling the contributions of chemical and mechanical stimuli. Here we highlight recent work demonstrating that surface attachment drives a transcriptional response in bacterial pathogens, including uropathogenic Escherichia coli (E. coli), and discuss the complexity of experimental design when dissecting the specific role of adhesion-mediated signaling during infection. PMID:26901228

  2. Notch1 endocytosis is induced by ligand and is required for signal transduction.

    PubMed

    Chapman, G; Major, J A; Iyer, K; James, A C; Pursglove, S E; Moreau, J L M; Dunwoodie, S L

    2016-01-01

    The Notch signalling pathway is widely utilised during embryogenesis in situations where cell-cell interactions are important for cell fate specification and differentiation. DSL ligand endocytosis into the ligand-expressing cell is an important aspect of Notch signalling because it is thought to supply the force needed to separate the Notch heterodimer to initiate signal transduction. A functional role for receptor endocytosis during Notch signal transduction is more controversial. Here we have used live-cell imaging to examine trafficking of the Notch1 receptor in response to ligand binding. Contact with cells expressing ligands induced internalisation and intracellular trafficking of Notch1. Notch1 endocytosis was accompanied by transendocytosis of ligand into the Notch1-expressing signal-receiving cell. Ligand caused Notch1 endocytosis into SARA-positive endosomes in a manner dependent on clathrin and dynamin function. Moreover, inhibition of endocytosis in the receptor-expressing cell impaired ligand-induced Notch1 signalling. Our findings resolve conflicting observations from mammalian and Drosophila studies by demonstrating that ligand-dependent activation of Notch1 signalling requires receptor endocytosis. Endocytosis of Notch1 may provide a force on the ligand:receptor complex that is important for potent signal transduction.

  3. Genetic Analysis of Gravity Signal Transduction in Arabidopsis Roots

    NASA Astrophysics Data System (ADS)

    Masson, Patrick; Strohm, Allison; Barker, Richard; Su, Shih-Heng

    Like most other plant organs, roots use gravity as a directional guide for growth. Specialized cells within the columella region of the root cap (the statocytes) sense the direction of gravity through the sedimentation of starch-filled plastids (amyloplasts). Amyloplast movement and/or pressure on sensitive membranes triggers a gravity signal transduction pathway within these cells, which leads to a fast transcytotic relocalization of plasma-membrane associated auxin-efflux carrier proteins of the PIN family (PIN3 and PIN7) toward the bottom membrane. This leads to a polar transport of auxin toward the bottom flank of the cap. The resulting lateral auxin gradient is then transmitted toward the elongation zones where it triggers a curvature that ultimately leads to a restoration of vertical downward growth. Our laboratory is using strategies derived from genetics and systems biology to elucidate the molecular mechanisms that modulate gravity sensing and signal transduction in the columella cells of the root cap. Our previous research uncovered two J-domain-containing proteins, ARG1 and ARL2, as contributing to this process. Mutations in the corresponding paralogous genes led to alterations of root and hypocotyl gravitropism accompanied by an inability for the statocytes to develop a cytoplasmic alkalinization, relocalize PIN3, and transport auxin laterally, in response to gravistimulation. Both proteins are associated peripherally to membranes belonging to various compartments of the vesicular trafficking pathway, potentially modulating the trafficking of defined proteins between plasma membrane and endosomes. MAR1 and MAR2, on the other end, are distinct proteins of the plastidic outer envelope protein import TOC complex (the transmembrane channel TOC75 and the receptor TOC132, respectively). Mutations in the corresponding genes enhance the gravitropic defects of arg1. Using transformation-rescue experiments with truncated versions of TOC132 (MAR2), we have shown

  4. Signal Transduction Model of Magnetic Sensing in Cryptochrome Mediated Photoreception

    NASA Astrophysics Data System (ADS)

    Todd, Phillise Tiffeny

    While migratory birds have long been known to use the Earth's magnetic field for navigation, the precise biophysical mechanism behind this magnetic sense remains unconfirmed. A leading theory of magnetoreception suggests a chemical compass model with a yet undetermined molecular reaction site and unknown magnetically sensitive reactants. The cryptochrome photoreceptor has emerged as a promising candidate site. This investigation numerically models the first order kinetics of cryptochrome mediated photoreception, in order to evaluate its ability to function as a magnetic sensor and transduce orientation information along a neural pathway. A signal-to-noise ratio is defined to quantify the threshold for the functioning of a cryptochrome-based chemical compass. The model suggests that a flavin-superoxide radical pair in cryptochrome functions as the chemical reactants for magnetoreception. Such a cryptochrome-based signal transduction model reasonably predicts the general light intensity and wavelength effects that have been experimentally observed in migratory birds.

  5. The role of protein kinase C in cell surface signal transduction and tumour promotion

    NASA Astrophysics Data System (ADS)

    Nishizuka, Yasutomi

    1984-04-01

    Protein kinase C has a crucial role in signal transduction for a variety of biologically active substances which activate cellular functions and proliferation. When cells are stimulated, protein kinase C is transiently activated by diacylglycerol which is produced in the membrane during the signal-induced turnover of inositol phospholipids. Tumour-promoting phorbol esters, when intercalated into the cell membrane, may substitute for diacylglycerol and permanently activate protein kinase C. The enzyme probably serves as a receptor for the tumour promoters. Further exploration of the roles of this enzyme may provide clues for understanding the mechanism of cell growth and differentiation.

  6. Signal transduction pathways and transcription factors triggered by arsenic trioxide in leukemia cells

    SciTech Connect

    Sumi, Daigo; Shinkai, Yasuhiro; Kumagai, Yoshito

    2010-05-01

    Arsenic trioxide (As{sub 2}O{sub 3}) is widely used to treat acute promyelocytic leukemia (APL). Several lines of evidence have indicated that As{sub 2}O{sub 3} affects signal transduction and transactivation of transcription factors, resulting in the stimulation of apoptosis in leukemia cells, because some transcription factors are reported to associate with the redox condition of the cells, and arsenicals cause oxidative stress. Thus, the disturbance and activation of the cellular signaling pathway and transcription factors due to reactive oxygen species (ROS) generation during arsenic exposure may explain the ability of As{sub 2}O{sub 3} to induce a complete remission in relapsed APL patients. In this report, we review recent findings on ROS generation and alterations in signal transduction and in transactivation of transcription factors during As{sub 2}O{sub 3} exposure in leukemia cells.

  7. [Current understanding of signaling transduction pathway and biological functions of Karrikins].

    PubMed

    Luo, Xiaofeng; Qi, Ying; Meng, Yongjie; Shuai, Haiwei; Chen, Feng; Yang, Wenyu; Shu, Kai

    2016-01-01

    Karrikins are a class of signaling molecules discovered in wildfire smoke, which can significantly promote seed germination in some species (such as Arabidopsis and Avena fatua). The structures of Karrikins were first elucidated in 2004. At present, six different types of Karrikins have been documented, and their biological activities vary significantly. So far, studies for Karrikins have become a hot spot in the plant molecular biology field. Recent advances demonstrate that Karrikins regulate plant photomorphogenesis and leaf differentiation effectively, in addition to the effect on seed germination. Furthermore, Karrikins share highly similar molecular structures and signaling transduction pathways with strigolactone. In this review, we summarize the history of discovery, signaling transduction pathways, physiological functions and ecological significance of Karrikins, and further discuss the future research directions. PMID:26787523

  8. Protein Tyrosine Phosphatases: From Housekeeping Enzymes to Master-Regulators of Signal Transduction

    PubMed Central

    Tonks, Nicholas K.

    2013-01-01

    There are many misconceptions surrounding the roles of protein phosphatases in the regulation of signal transduction, perhaps the most damaging of which is the erroneous view that these enzymes exert their effects merely as constitutively active housekeeping enzymes. On the contrary, the phosphatases are critical, specific regulators of signaling in their own right and serve an essential function, in a coordinated manner with the kinases, to determine the response to a physiological stimulus. This review is a personal perspective on the development of our understanding of the protein tyrosine phosphatase (PTP) family of enzymes. I have discussed various aspects of the structure, regulation and function of the PTP family, which I hope will illustrate the fundamental importance of these enzymes to the control of signal transduction. PMID:23176256

  9. Analysis of the gravitaxis signal transduction chain in Euglena gracilis

    NASA Astrophysics Data System (ADS)

    Nasir, Adeel

    Abstract Euglena gracilis is a photosynthetic, eukaryotic flagellate. It can adapt autotrophic and heterotrophic mode of growth and respond to different stimuli, this makes it an organism of choice for different research disciplines. It swims to reach a suitable niche by employing different stimuli such as oxygen, light, gravity and different chemicals. Among these stimuli light and gravity are the most important. Phototaxis (locomotion under light stimulus) and gravitaxis (locomotion under gravity stimulus) synergistically help cells to attain an optimal niche in the environment. However, in the complete absence of light or under scarcity of detectable light, cells can totally depend on gravity to find its swimming path. Therefore gravity has certain advantages over other stimuli.Unlike phototatic signal transduction chain of Euglena gracilis no clear primary gravity receptor has been identified in Euglena cells so far. However, there are some convincing evidence that TRP like channels act as a primary gravity receptor in Euglena gracilis.Use of different inhibitors gave rise to the involvement of protein kinase and calmodulin proteins in signal transduction chain of Euglena gracilis. Recently, specific calmodulin (Calmodulin 2) and protein kinase (PKA) have been identified as potential candidates of gravitactic signal transduction chain. Further characterization and investigation of these candidates was required. Therefore a combination of biochemical and genetic techniques was employed to localize proteins in cells and also to find interacting partners. For localization studies, specific antibodies were raised and characterized. Specificity of antibodies was validated by knockdown mutants, Invitro-translated proteins and heterologously expressed proteins. Cell fractionation studies, involving separation of the cell body and flagella for western blot analysis and confocal immunofluorescence studies were performed for subcellular localization. In order to find

  10. Calcitonin gene-related peptide promotes the expression of osteoblastic genes and activates the WNT signal transduction pathway in bone marrow stromal stem cells

    PubMed Central

    ZHOU, RI; YUAN, ZHI; LIU, JIERONG; LIU, JIAN

    2016-01-01

    Calcitonin gene-related peptide (CGRP) is known to induce osteoblastic differentiation and alkaline phosphatase activity in bone marrow stromal stem cells (BMSCs). However, it has remained elusive whether this effect is mediated by CGRP receptors directly or whether other signaling pathways are involved. The present study assessed the possible involvement of the Wnt/β-catenin signaling pathway in the activation of CGRP signaling during the differentiation of BMSCs. First, the differentiation of BMSCs was induced in vitro and the expression of CGRP receptors was examined by western blot analysis. The effects of exogenous CGRP and LiCl, a stimulator of the Wnt/β-catenin signaling pathway, on the osteoblastic differentiation of BMSCs were assessed; furthermore, the expression of mRNA and proteins involved in the Wnt/β-catenin signaling pathway was assessed using quantitative PCR and western blot analyses. The results revealed that CGRP receptors were expressed throughout the differentiation of BMSCs, at days 7 and 14. Incubation with CGRP and LiCl led to the upregulation of the expression of osteoblastic genes associated with the Wnt/β-catenin pathway, including the mRNA of c-myc, cyclin D1, Lef1, Tcf7 and β-catenin as well as β-catenin protein. However, the upregulation of these genes and β-catenin protein was inhibited by CGRP receptor antagonist or secreted frizzled-related protein, an antagonist of the Wnt/β-catenin pathway. The results of the present study therefore suggested that the Wnt/β-catenin signaling pathway may be involved in CGRP- and LiCl-promoted osteoblastic differentiation of BMSCs. PMID:27082317

  11. Application of Petri net based analysis techniques to signal transduction pathways

    PubMed Central

    Sackmann, Andrea; Heiner, Monika; Koch, Ina

    2006-01-01

    Background Signal transduction pathways are usually modelled using classical quantitative methods, which are based on ordinary differential equations (ODEs). However, some difficulties are inherent in this approach. On the one hand, the kinetic parameters involved are often unknown and have to be estimated. With increasing size and complexity of signal transduction pathways, the estimation of missing kinetic data is not possible. On the other hand, ODEs based models do not support any explicit insights into possible (signal-) flows within the network. Moreover, a huge amount of qualitative data is available due to high-throughput techniques. In order to get information on the systems behaviour, qualitative analysis techniques have been developed. Applications of the known qualitative analysis methods concern mainly metabolic networks. Petri net theory provides a variety of established analysis techniques, which are also applicable to signal transduction models. In this context special properties have to be considered and new dedicated techniques have to be designed. Methods We apply Petri net theory to model and analyse signal transduction pathways first qualitatively before continuing with quantitative analyses. This paper demonstrates how to build systematically a discrete model, which reflects provably the qualitative biological behaviour without any knowledge of kinetic parameters. The mating pheromone response pathway in Saccharomyces cerevisiae serves as case study. Results We propose an approach for model validation of signal transduction pathways based on the network structure only. For this purpose, we introduce the new notion of feasible t-invariants, which represent minimal self-contained subnets being active under a given input situation. Each of these subnets stands for a signal flow in the system. We define maximal common transition sets (MCT-sets), which can be used for t-invariant examination and net decomposition into smallest biologically

  12. In search of cellular control: signal transduction in context

    NASA Technical Reports Server (NTRS)

    Ingber, D.

    1998-01-01

    The field of molecular cell biology has experienced enormous advances over the last century by reducing the complexity of living cells into simpler molecular components and binding interactions that are amenable to rigorous biochemical analysis. However, as our tools become more powerful, there is a tendency to define mechanisms by what we can measure. The field is currently dominated by efforts to identify the key molecules and sequences that mediate the function of critical receptors, signal transducers, and molecular switches. Unfortunately, these conventional experimental approaches ignore the importance of supramolecular control mechanisms that play a critical role in cellular regulation. Thus, the significance of individual molecular constituents cannot be fully understood when studied in isolation because their function may vary depending on their context within the structural complexity of the living cell. These higher-order regulatory mechanisms are based on the cell's use of a form of solid-state biochemistry in which molecular components that mediate biochemical processing and signal transduction are immobilized on insoluble cytoskeletal scaffolds in the cytoplasm and nucleus. Key to the understanding of this form of cellular regulation is the realization that chemistry is structure and hence, recognition of the the importance of architecture and mechanics for signal integration and biochemical control. Recent work that has unified chemical and mechanical signaling pathways provides a glimpse of how this form of higher-order cellular control may function and where paths may lie in the future.

  13. Reactive oxygen species mediate insulin signal transduction in mouse hypothalamus.

    PubMed

    Onoue, Takeshi; Goto, Motomitsu; Tominaga, Takashi; Sugiyama, Mariko; Tsunekawa, Taku; Hagiwara, Daisuke; Banno, Ryoichi; Suga, Hidetaka; Sugimura, Yoshihisa; Arima, Hiroshi

    2016-04-21

    In the hypothalamus, several reports have implied that ROS mediate physiological effects of insulin. In this study, we investigated the mechanisms of insulin-induced ROS production and the effect of ROS on insulin signal transduction in mouse hypothalamic organotypic cultures. Insulin increased intracellular ROS, which were suppressed by NADPH oxidase inhibitor. H2O2 increased phospho-insulin receptor β (p-IRβ) and phospho-Akt (p-Akt) levels. Insulin-induced increases in p-IRβ and p-Akt levels were attenuated by ROS scavenger or NADPH oxidase inhibitor. Our data suggest that insulin-induced phosphorylation of IRβ and Akt is mediated via ROS which are predominantly produced by NADPH oxidase in mouse hypothalamus.

  14. Simulation of signal transduction in model multiprotein systems

    NASA Astrophysics Data System (ADS)

    Su, Julius

    2009-03-01

    To simulate the dynamics of multiprotein machines, I have developed a method called multiconformer Brownian dynamics (mcBD). In this method, proteins rotate and translate via Brownian motion while their conformations are varied among a prestored set of structures on a simplified energy landscape, taking into account inter-protein interactions. As an example, I build a simple model of a G-protein coupled receptor/G-protein complex, and show that ligand binding causes conformational shifts, which induce GDP to leave, GTP to bind, and the complex to dissociate. The two proteins couple their fast fluctuations together into large-scale coordinated functional motions, resulting in signal transduction. I vary the shapes, electrostatics, and energy landscapes of the proteins independently and examine the impact this has on the system's function. In one result, increasing the binding between proteins improves the fidelity of communication, but at the expense of overall switching frequency.

  15. Interferons, Signal Transduction Pathways, and the Central Nervous System

    PubMed Central

    Nallar, Shreeram C.

    2014-01-01

    The interferon (IFN) family of cytokines participates in the development of innate and acquired immune defenses against various pathogens and pathogenic stimuli. Discovered originally as a proteinaceous substance secreted from virus-infected cells that afforded immunity to neighboring cells from virus infection, these cytokines are now implicated in various human pathologies, including control of tumor development, cell differentiation, and autoimmunity. It is now believed that the IFN system (IFN genes and the genes induced by them, and the factors that regulate these processes) is a generalized alarm of cellular stress, including DNA damage. IFNs exert both beneficial and deleterious effects on the central nervous system (CNS). Our knowledge of the IFN-regulated processes in the CNS is far from being clear. In this article, we reviewed the current understanding of IFN signal transduction pathways and gene products that might have potential relevance to diseases of the CNS. PMID:25084173

  16. Molecular immunology--gene regulation and signal transduction.

    PubMed

    Hopkins, John

    2002-09-10

    Research on 'molecular immunology-gene regulation and signal transduction' in veterinary species is relatively new. The reason for its novelty is that until recently there have been very few tools with which we can work. Over the last 10 years the veterinary immunology community has succeeded in generating panels of defined monoclonal antibodies (mAb) and cloned genes that has enabled such work to be started. More recently, quantitative, high-resolution analytical tools for veterinary species have begun to be developed; some of these are specific for veterinary species and others have been adapted from human or rodent systems. Of the species-specific tools that have recently been developed perhaps the most widely used are the immunoassays for cytokines, RNAase protection assays (RPAs) and in the near future oligonucleotide and EST-based microarrays. This presentation will describe some of these assays and discuss their relative advantages and disadvantages.

  17. Interferons, signal transduction pathways, and the central nervous system.

    PubMed

    Nallar, Shreeram C; Kalvakolanu, Dhan V

    2014-08-01

    The interferon (IFN) family of cytokines participates in the development of innate and acquired immune defenses against various pathogens and pathogenic stimuli. Discovered originally as a proteinaceous substance secreted from virus-infected cells that afforded immunity to neighboring cells from virus infection, these cytokines are now implicated in various human pathologies, including control of tumor development, cell differentiation, and autoimmunity. It is now believed that the IFN system (IFN genes and the genes induced by them, and the factors that regulate these processes) is a generalized alarm of cellular stress, including DNA damage. IFNs exert both beneficial and deleterious effects on the central nervous system (CNS). Our knowledge of the IFN-regulated processes in the CNS is far from being clear. In this article, we reviewed the current understanding of IFN signal transduction pathways and gene products that might have potential relevance to diseases of the CNS.

  18. A hypothesis-effect of T cell epitope fusion peptide specific immunotherapy on signal transduction

    PubMed Central

    Li, Chao-Pin; Yang, Bang-He

    2015-01-01

    Asthma is a chronic nonspecific inflammatory disease of the airway primarily mediated by different inflammatory cells, including mast cells, eosinophils and T cells. We hereby specially focused on a signal pathway for Janus kinase-signal transducer and activators of transduction (JAK-STATs), which has been the interest of study in asthma since it more likely regulates cellular proliferation and differentiation, and consequently modulates immune system. In our consideration, knowledge on this signal pathway may provide an avenue for rational options in treatment of asthma on control of immune response basis. PMID:26770626

  19. Role of Glycolytic Intermediates in Global Regulation and Signal Transduction. Final Report

    SciTech Connect

    Liao, J.C.

    2000-05-08

    The goal of this project is to determine the role of glycolytic intermediates in regulation of cell physiology. It is known that many glycolytic intermediates are involved in regulation of enzyme activities at the kinetic level. However, little is known regarding the role of these metabolites in global regulation and signal transduction. This project aims to investigate the role of glycolytic intermediates in the regulation of gene expression.

  20. Mitochondria-derived hydrogen peroxide selectively enhances T cell receptor-initiated signal transduction.

    PubMed

    Gill, Tejpal; Levine, Alan D

    2013-09-01

    T cell receptor (TCR)-initiated signal transduction is reported to increase production of intracellular reactive oxygen species, such as superoxide (O2˙(-)) and hydrogen peroxide (H2O2), as second messengers. Although H2O2 can modulate signal transduction by inactivating protein phosphatases, the mechanism and the subcellular localization of intracellular H2O2 as a second messenger of the TCR are not known. The antioxidant enzyme superoxide dismutase (SOD) catalyzes the dismutation of highly reactive O2˙(-) into H2O2 and thus acts as an intracellular generator of H2O2. As charged O2˙(-) is unable to diffuse through intracellular membranes, cells express distinct SOD isoforms in the cytosol (Cu,Zn-SOD) and mitochondria (Mn-SOD), where they locally scavenge O2˙(-) leading to production of H2O2. A 2-fold organelle-specific overexpression of either SOD in Jurkat T cell lines increases intracellular production of H2O2 but does not alter the levels of intracellular H2O2 scavenging enzymes such as catalase, membrane-bound peroxiredoxin1 (Prx1), and cytosolic Prx2. We report that overexpression of Mn-SOD enhances tyrosine phosphorylation of TCR-associated membrane proximal signal transduction molecules Lck, LAT, ZAP70, PLCγ1, and SLP76 within 1 min of TCR cross-linking. This increase in mitochondrial H2O2 specifically modulates MAPK signaling through the JNK/cJun pathway, whereas overexpressing Cu,Zn-SOD had no effect on any of these TCR-mediated signaling molecules. As mitochondria translocate to the immunological synapse during TCR activation, we hypothesize this translocation provides the effective concentration of H2O2 required to selectively modulate downstream signal transduction pathways.

  1. An integrated model of epidermal growth factor receptor trafficking and signal transduction.

    PubMed

    Resat, Haluk; Ewald, Jonathan A; Dixon, David A; Wiley, H Steven

    2003-08-01

    Endocytic trafficking of many types of receptors can have profound effects on subsequent signaling events. Quantitative models of these processes, however, have usually considered trafficking and signaling independently. Here, we present an integrated model of both the trafficking and signaling pathway of the epidermal growth factor receptor (EGFR) using a probability weighted-dynamic Monte Carlo simulation. Our model consists of hundreds of distinct endocytic compartments and approximately 13,000 reactions/events that occur over a broad spatio-temporal range. By using a realistic multicompartment model, we can investigate the distribution of the receptors among cellular compartments as well as their potential signal transduction characteristics. Our new model also allows the incorporation of physiochemical aspects of ligand-receptor interactions, such as pH-dependent binding in different endosomal compartments. To determine the utility of this approach, we simulated the differential activation of the EGFR by two of its ligands, epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha). Our simulations predict that when EGFR is activated with TGF-alpha, receptor activation is biased toward the cell surface whereas EGF produces a signaling bias toward the endosomal compartment. Experiments confirm these predictions from our model and simulations. Our model accurately predicts the kinetics and extent of receptor downregulation induced by either EGF or TGF-alpha. Our results suggest that receptor trafficking controls the compartmental bias of signal transduction, rather than simply modulating signal magnitude. Our model provides a new approach to evaluating the complex effect of receptor trafficking on signal transduction. Importantly, the stochastic and compartmental nature of the simulation allows these models to be directly tested by high-throughput approaches, such as quantitative image analysis. PMID:12885624

  2. An Integrated Model of Epidermal Growth Factor Receptor Trafficking and Signal Transduction

    SciTech Connect

    Resat, Haluk; Ewald, Jonathan A.; Dixon, David A.; Wiley, H. S.

    2003-08-01

    Endocytic trafficking of many types of receptors can have profound effects on subsequent signaling events. Quantitative models of these processes, however, have usually considered trafficking and signaling independently. Here, we present an integrated model of both the trafficking and signaling pathway of the epidermal growth factor receptor (EGFR) using a probability weighted-dynamic Monte Carlo simulation. Our model consists of hundreds of distinct endocytic compartments and about 13,000 reactions/events that occur over a broad spatio-temporal range. By using a realistic multi-compartment model, we can investigate the distribution of the receptors among cellular compartments as well as their potential signal transduction characteristics. Our new model also allows the incorporation of physio-chemical aspects of ligand-receptor interactions, such as pH-dependent binding in different endosomal compartments. To determine the utility of this approach, we simulated the differential activation of the EGFR by two of its ligands, epidermal growth factor (EGF) and transforming growth factor- alpha (TGF-a). Our simulations predict that when EGFR is activated with TGF-a, receptor activation is biased toward the cell surface whereas EGF produces a signaling bias towards the endosomal compartment. Experiments confirm these predictions from our model and simulations. Our model accurately predicts the kinetics and extent of receptor down-regulation induced by either EGF or TGF-a. Our results suggest that receptor trafficking controls the compartmental bias of signal transduction, rather than simply modulating signal magnitude. Our model provides a new approach to evaluating the complex effect of receptor trafficking on signal transduction. Importantly, the stochastic and compartmental nature of the simulation allows these models to be directly tested by high-throughput approaches, such as quantitative image analysis.

  3. Glucose oxidase facilitates osteogenic differentiation and mineralization of embryonic stem cells through the activation of Nrf2 and ERK signal transduction pathways.

    PubMed

    Sim, Hyun-Jaung; Kim, Jae-Hwan; Kook, Sung-Ho; Lee, Seung-Youp; Lee, Jeong-Chae

    2016-08-01

    Nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/heme oxygenase-1 (HO-1) signal is known to play important roles in controlling bone homeostasis. This study examined how oxidative stress affects the mineralization of embryonic stem (ES) cells by exposing them to glucose oxidase (GO), which continuously generates H2O2 at low concentrations. The roles of Nrf2/HO-1 and mitogen-activated protein kinases on osteogenesis in GO-exposed ES cells were also investigated. GO treatment at relatively low concentrations did not change the viability of ES cells, whereas it enhanced osteogenic differentiation and mineralization in the cells. GO treatment (1 mU/ml) augmented the induction of runt-related transcription factor 2 (Runx2), Nrf2, and HO-1 in ES cells. GO-mediated acceleration of Runx2 expression and mineralization was inhibited either by Nrf2 knockdown or by treating with 5 μM PD98059, an inhibitor of phospho-extracellular signal-regulated kinase (p-ERK). The GO-stimulated mineralization was also suppressed by treating the cells with reduced glutathione or catalase, but not by superoxide dismutase or N-acetyl-cysteine. Collectively, our results demonstrate that a mild oxidative stress activates Nrf2/HO-1 signaling and an ERK-mediated pathway, and facilitates the mineralization of ES cells with a corresponding increase in Runx2.

  4. Receptor clustering affects signal transduction at the membrane level in the reaction-limited regime

    NASA Astrophysics Data System (ADS)

    Caré, Bertrand R.; Soula, Hédi A.

    2013-01-01

    Many types of membrane receptors are found to be organized as clusters on the cell surface. We investigate the potential effect of such receptor clustering on the intracellular signal transduction stage. We consider a canonical pathway with a membrane receptor (R) activating a membrane-bound intracellular relay protein (G). We use Monte Carlo simulations to recreate biochemical reactions using different receptor spatial distributions and explore the dynamics of the signal transduction. Results show that activation of G by R is severely impaired by R clustering, leading to an apparent blunted biological effect compared to control. Paradoxically, this clustering decreases the half maximal effective dose (ED50) of the transduction stage, increasing the apparent affinity. We study an example of inter-receptor interaction in order to account for possible compensatory effects of clustering and observe the parameter range in which such interactions slightly counterbalance the loss of activation of G. The membrane receptors’ spatial distribution affects the internal stages of signal amplification, suggesting a functional role for membrane domains and receptor clustering independently of proximity-induced receptor-receptor interactions.

  5. Information content and cross-talk in biological signal transduction: An information theory study

    NASA Astrophysics Data System (ADS)

    Prasad, Ashok; Lyons, Samanthe

    2014-03-01

    Biological cells respond to chemical cues provided by extra-cellular chemical signals, but many of these chemical signals and the pathways they activate interfere and overlap with one another. How well cells can distinguish between interfering extra-cellular signals is thus an important question in cellular signal transduction. Here we use information theory with stochastic simulations of networks to address the question of what happens to total information content when signals interfere. We find that both total information transmitted by the biological pathway, as well as its theoretical capacity to discriminate between overlapping signals, are relatively insensitive to cross-talk between the extracellular signals, until significantly high levels of cross-talk have been reached. This robustness of information content against cross-talk requires that the average amplitude of the signals are large. We predict that smaller systems, as exemplified by simple phosphorylation relays (two-component systems) in bacteria, should be significantly much less robust against cross-talk. Our results suggest that mammalian signal transduction can tolerate a high amount of cross-talk without degrading information content, while smaller bacterial systems cannot.

  6. Two distinct alpha-interferon-dependent signal transduction pathways may contribute to activation of transcription of the guanylate-binding protein gene

    SciTech Connect

    Decker, T.; Lew, D.J.; Darnell, J.E. Jr. )

    1991-10-01

    The promoter of the gene encoding a cytoplasmic guanylate-binding (GBP) contains two overlapping elements: the interferon stimulation response element (ISRE), which mediates alpha interferon (IFN-{alpha})-dependent transcription, and the IFN-{gamma} activation site (GAS), which is required for INF-{gamma}-mediated stimulation. The ISRE binds a factor called ISGF-3 that is activated by IFN-{alpha} but not by IFN-{gamma}. The GAS binds a protein that is activated by IFN-{gamma}, which the authors have termed GAF. The authors now find that the GAS is also an IFN-{alpha}-responsive element in vivo and that IFN-{alpha} (in addition to activating ISGF-3) rapidly activates a GAS-binding factor, the IFN-{alpha} activation factor (AAF). The AAF has characteristics very similar to those of the previously described GAF. Through the use of inhibitors of protein synthesis and inhibitors of protein kinases, the activation conditions of AAF, GAF, and ISGF-3 could be distinguished. Therefore, not only do IFN-{alpha} and IFN-{gamma} stimulate transcription of GBP through different receptors linked to different signaling molecules, but occupation of the IFN-{alpha} receptor apparently leads to the rapid activation of two different DNA-binding proteins through the use of different intracellular pathways.

  7. Novel pathway in Bcr-Abl signal transduction involves Akt-independent, PLC-gamma1-driven activation of mTOR/p70S6-kinase pathway.

    PubMed

    Markova, B; Albers, C; Breitenbuecher, F; Melo, J V; Brümmendorf, T H; Heidel, F; Lipka, D; Duyster, J; Huber, C; Fischer, T

    2010-02-01

    In chronic myeloid leukemia, activation of the phosphoinositide 3-kinase (PI3K)/Akt pathway is crucial for survival and proliferation of leukemic cells. Essential downstream molecules involve mammalian target of rapamycin (mTOR) and S6-kinase. Here, we present a comprehensive analysis of the molecular events involved in activation of these key signaling pathways. We provide evidence for a previously unrecognized phospholipase C-gamma1 (PLC-gamma1)-controlled mechanism of mTOR/p70S6-kinase activation, which operates in parallel to the classical Akt-dependent machinery. Short-term imatinib treatment of Bcr-Abl-positive cells caused dephosphorylation of p70S6-K and S6-protein without inactivation of Akt. Suppression of Akt activity alone did not affect phosphorylation of p70-S6K and S6. These results suggested the existence of an alternative mechanism for mTOR/p70S6-K activation. In Bcr-Abl-expressing cells, we detected strong PLC-gamma1 activation, which was suppressed by imatinib. Pharmacological inhibition and siRNA knockdown of PLC-gamma1 blocked p70S6-K and S6 phosphorylation. By inhibiting the Ca-signaling, CaMK and PKCs we demonstrated participation of these molecules in the pathway. Suppression of PLC-gamma1 led to inhibition of cell proliferation and enhanced apoptosis. The novel pathway proved to be essential for survival and proliferation of leukemic cells and almost complete cell death was observed upon combined PLC-gamma1 and Bcr-Abl inhibition. The pivotal role of PLC-gamma1 was further confirmed in a mouse leukemogenesis model.

  8. The application of multiple biophysical cues to engineer functional neocartilage for treatment of osteoarthritis. Part II: signal transduction.

    PubMed

    Brady, Mariea A; Waldman, Stephen D; Ethier, C Ross

    2015-02-01

    The unique mechanoelectrochemical environment of cartilage has motivated researchers to investigate the effect of multiple biophysical cues, including mechanical, magnetic, and electrical stimulation, on chondrocyte biology. It is well established that biophysical stimuli promote chondrocyte proliferation, differentiation, and maturation within "biological windows" of defined dose parameters, including mode, frequency, magnitude, and duration of stimuli (see companion review Part I: Cellular Response). However, the underlying molecular mechanisms and signal transduction pathways activated in response to multiple biophysical stimuli remain to be elucidated. Understanding the mechanisms of biophysical signal transduction will deepen knowledge of tissue organogenesis, remodeling, and regeneration and aiding in the treatment of pathologies such as osteoarthritis. Further, this knowledge will provide the tissue engineer with a potent toolset to manipulate and control cell fate and subsequently develop functional replacement cartilage. The aim of this article is to review chondrocyte signal transduction pathways in response to mechanical, magnetic, and electrical cues. Signal transduction does not occur along a single pathway; rather a number of parallel pathways appear to be activated, with calcium signaling apparently common to all three types of stimuli, though there are different modes of activation. Current tissue engineering strategies, such as the development of "smart" functionalized biomaterials that enable the delivery of growth factors or integration of conjugated nanoparticles, may further benefit from targeting known signal transduction pathways in combination with external biophysical cues. PMID:25065615

  9. Interplay of Specific Trans- and Juxtamembrane Interfaces in Plexin A3 Dimerization and Signal Transduction.

    PubMed

    Barton, Rachael; Khakbaz, Pouyan; Bera, Indrani; Klauda, Jeffery B; Iovine, M Kathryn; Berger, Bryan W

    2016-09-01

    Plexins are transmembrane proteins that serve as guidance receptors during angiogenesis, lymphangiogenesis, neuronal development, and zebrafish fin regeneration, with a putative role in cancer metastasis. Receptor dimerization or clustering, induced by extracellular ligand binding but modulated in part by the plexin transmembrane (TM) and juxtamembrane (JM) domains, is thought to drive plexin activity. Previous studies indicate that isolated plexin TM domains interact through a conserved, small-x3-small packing motif, and the cytosolic JM region interacts through a hydrophobic heptad repeat; however, the roles and interplay of these regions in plexin signal transduction remain unclear. Using an integrated experimental and simulation approach, we find disruption of the small-x3-small motifs in the Danio rerio Plexin A3 TM domain enhances dimerization of the TM-JM domain by enhancing JM-mediated dimerization. Furthermore, mutations of the cytosolic JM heptad repeat that disrupt dimerization do so even in the presence of TM domain mutations. However, mutations to the small-x3-small TM interfaces also disrupt Plexin A3 signaling in a zebrafish axonal guidance assay, indicating the importance of this TM interface in signal transduction. Collectively, our experimental and simulation results demonstrate that multiple TM and JM interfaces exist in the Plexin A3 homodimer, and these interfaces independently regulate dimerization that is important in Plexin A3 signal transduction.

  10. Osmotin, a plant antifungal protein, subverts signal transduction to enhance fungal cell susceptibility.

    PubMed

    Yun, D J; Ibeas, J I; Lee, H; Coca, M A; Narasimhan, M L; Uesono, Y; Hasegawa, P M; Pardo, J M; Bressan, R A

    1998-05-01

    The plant pathogenesis-related protein osmotin is an antifungal cytotoxic agent that causes rapid cell death in the yeast S. cerevisiae. We show here that osmotin uses a signal transduction pathway to weaken defensive cell wall barriers and increase its cytotoxic efficacy. The pathway activated by osmotin includes the regulatory elements of the mating pheromone response STE4, STE18, STE20, STE5, STE11, STE7, FUS3, KSS1, and STE12. Neither the pheromone receptor nor its associated G protein alpha subunit GPA1 are required for osmotin action. However, mutation of SST2, a negative regulator of G alpha proteins, resulted in supersensitivity to osmotin. Phosphorylation of STE7 was rapidly stimulated by osmotin preceding any changes in cell vitality or morphology. These results demonstrate that osmotin subverts target cell signal transduction as part of its mechanism of action. PMID:9660964

  11. Structural insight into partner specificity and phosphoryl transfer in two-component signal transduction.

    PubMed

    Casino, Patricia; Rubio, Vicente; Marina, Alberto

    2009-10-16

    The chief mechanism used by bacteria for sensing their environment is based on two conserved proteins: a sensor histidine kinase (HK) and an effector response regulator (RR). The signal transduction process involves highly conserved domains of both proteins that mediate autokinase, phosphotransfer, and phosphatase activities whose output is a finely tuned RR phosphorylation level. Here, we report the structure of the complex between the entire cytoplasmic portion of Thermotoga maritima class I HK853 and its cognate, RR468, as well as the structure of the isolated RR468, both free and BeF(3)(-) bound. Our results provide insight into partner specificity in two-component systems, recognition of the phosphorylation state of each partner, and the catalytic mechanism of the phosphatase reaction. Biochemical analysis shows that the HK853-catalyzed autokinase reaction proceeds by a cis autophosphorylation mechanism within the HK subunit. The results suggest a model for the signal transduction mechanism in two-component systems.

  12. Regulation of drug-induced liver injury by signal transduction pathways: critical role of mitochondria

    PubMed Central

    Han, Derick; Dara, Lily; Win, Sanda; Than, Tin Aung; Yuan, Liyun; Abbasi, Sadeea Q; Liu, Zhang-Xu; Kaplowitz, Neil

    2013-01-01

    Drugs that cause liver injury often “stress” mitochondria and activate signal transduction pathways important in determining cell survival or death. In most cases, hepatocytes adapt to the drug-induced stress by activating adaptive signaling pathways, such as mitochondrial adaptive responses and erythroid 2-related factor 2 (Nrf-2), a transcription factor that upregulates antioxidant defenses. Due to adaptation, drugs alone rarely cause liver injury, with acetaminophen being the notable exception. Drug-induced liver injury (DILI) usually involves other extrinsic factors, such as the adaptive immune system, that cause “stressed” hepatocytes to become injured; leading to idiosyncratic DILI, the rare and unpredictable adverse drug reaction in the liver. Hepatocyte injury, due to drug and extrinsic insult, causes a second wave of signaling changes associated with adaptation, cell death, and repair. If the stress and injury reach a critical threshold, then death signaling pathways such as JNK become dominant and hepatocytes enter a failsafe mode to undergo self-destruction. DILI can be seen as an active process involving recruitment of death signaling pathways that mediate cell death rather than a passive process due to overwhelming biochemical injury. In this review, we highlight the role of signal transduction pathways, which frequently involve mitochondria, in the development of DILI. PMID:23453390

  13. Regulation of drug-induced liver injury by signal transduction pathways: critical role of mitochondria.

    PubMed

    Han, Derick; Dara, Lily; Win, Sanda; Than, Tin Aung; Yuan, Liyun; Abbasi, Sadeea Q; Liu, Zhang-Xu; Kaplowitz, Neil

    2013-04-01

    Drugs that cause liver injury often 'stress' mitochondria and activate signal transduction pathways important in determining cell survival or death. In most cases, hepatocytes adapt to the drug-induced stress by activating adaptive signaling pathways, such as mitochondrial adaptive responses and nuclear factor erythroid 2-related factor 2 (Nrf-2), a transcription factor that upregulates antioxidant defenses. Owing to adaptation, drugs alone rarely cause liver injury, with acetaminophen (APAP) being the notable exception. Drug-induced liver injury (DILI) usually involves other extrinsic factors, such as the adaptive immune system, that cause 'stressed' hepatocytes to become injured, leading to idiosyncratic DILI, the rare and unpredictable adverse drug reaction in the liver. Hepatocyte injury, due to drug and extrinsic insult, causes a second wave of signaling changes associated with adaptation, cell death, and repair. If the stress and injury reach a critical threshold, then death signaling pathways such as c-Jun N-terminal kinase (JNK) become dominant and hepatocytes enter a failsafe mode to undergo self-destruction. DILI can be seen as an active process involving recruitment of death signaling pathways that mediate cell death rather than a passive process due to overwhelming biochemical injury. In this review, we highlight the role of signal transduction pathways, which frequently involve mitochondria, in the development of DILI. PMID:23453390

  14. Sevoflurane Stimulates MAP Kinase Signal transduction through the Activation of PKC α and βII in Fetal Rat Cerebral Cortex Cultured Neuron

    PubMed Central

    Hasegawa, Jun; Takekoshi, Susumu; Nagata, Hidetaka; Osamura, R. Yoshiyuki; Suzuki, Toshiyasu

    2006-01-01

    Protein kinase C (PKC) is a key enzyme that participates in various neuronal functions. PKC has also been identified as a target molecule for general anesthetic actions. Raf, mitogen-activated protein kinase (MEK) and extracellular signal-regulated kinase (ERK1/2) have been thought to be target effectors of PKC. In the present study, we attempted to evaluate the effect of sevoflurane on PKC/MAPK cascade signaling in cultured fetal rat cerebral ­cortex neurons, prepared from embryonic day 18 fetuses. The effects of sevoflurane on the translocation of 7 PKC isoforms (α, βI, βII, γ, δ, ɛ and ζ) were observed by immunoblotting using isoform-selective antibodies to PKCs. The treatment of neurons with sevoflurane induced the translocation of PKC α and PKC βII species from the cytosol to the membrane fraction, which indicated the activation of these PKC isoforms. In contrast, there was no clear change in the distribution of other PKC isoforms. We next examined whether the specific activation of PKC α and βII by sevoflurane could stimulate the MAP kinase signaling pathway in cultured neurons. Raf phosphorylation was increased by the administration of 0.25 mM sevoflurane. The phosphorylation of Raf proteins reached a maximum at 5–10 min. Subsequently, the phosphorylation of MEK proteins was increased at 10–15 min after sevoflurane treatments. That of ERK proteins was induced at 15–60 min. Moreover, the phosphorylation of ERK induced by sevoflurane was significantly decreased by the treatment of PKC inhibitor (staurosporine) and MEK inhibitor (PD98059). On the other hand, the contents of total Raf, MEK and ERK proteins were relatively constant at all times examined. To examine the ­localization of phosphorylated-ERK protein, immunohistochemical staining of sevoflurane-treated cultured neurons was performed. The phosphorylated-ERK proteins were markedly accumulated in both the cytosol of the cell body and the neurites in the neuronal cells with time after 0

  15. Induction of proinflammatory mediators requires activation of the TRAF, NIK, IKK and NF-κB signal transduction pathway in astrocytes infected with Escherichia coli

    PubMed Central

    Kim, J M; Oh, Y-K; Lee, J H; Im, D Y; Kim, Y-J; Youn, J; Lee, C-H; Son, H; Lee, Y-S; Park, J Y; Choi, I-H

    2005-01-01

    Escherichia coli is associated with inflammation in the brain. To investigate whether astrocytes are involved in E. coil-induced inflammation, we assessed the levels of expression of proinflammatory mediators produced by E. coli-infected astrocytes. E. coli infection in primary human astrocytes and cell lines increased expression of the CXC chemokine IL-8/GRO-α, the CC chemokine MCP-1, TNF-α, and iNOS. E. coli infection activated p65/p50 heterodimeric NF-κB and concurrently decreased the signals of IκBα. Blocking the NF-κB signals by IκBα-superrepressor-containing retrovirus or antisense p50 oligonucleotide transfection resulted in down-regulation of expression of the proinflammatory mediators. Furthermore, superrepressors of IκBα, IκB kinase (IKK) or NF-κB inducing kinase (NIK) inhibited the up-regulated expression of the downstream target genes of NF-κB such as IL-8 and MCP-1, and superrepressors of TNF receptor-associated factor (TRAF)2 and TRAF5 also inhibited expression of the E. coli-induced target genes of NF-κB. These results indicate that proinflammatory mediators such as the CXC chemokine IL-8/GRO-α, the CC chemokine MCP-1, TNF-α, and iNOS can be expressed in E. coli-infected astrocytes via an NF-κB pathway, suggesting that these mediators may contribute to inflammation in the brain, including infiltration of inflammatory cells. PMID:15932506

  16. Altered mitogen-activated protein kinase signal transduction in human skin fibroblasts during in vitro aging: differential expression of low-density lipoprotein receptor.

    PubMed

    Bose, Chhanda; Bhuvaneswaran, Chidambaram; Udupa, Kodetthoor B

    2004-02-01

    The purpose of the study was to investigate the correlation of low-density lipoprotein receptor (LDLr) and mitogen-activated protein kinases (MAPK) in fibroblasts after serial passage in vitro. We used early-passage ( approximately 20 mean population division, MPD) and late-passage ( approximately 60 MPD) human skin fibroblasts to study the LDLr expression and MAPK at basal and after interleukin-1beta (IL-1beta) stimulation. We found a reduced LDLr expression in late-passage fibroblasts in comparison with early-passage fibroblasts, and late-passage fibroblasts showed a delayed induction of MAPK after IL-1beta stimulation, confirmed by the delay in translocation of MAPK from cytoplasmic to nuclear fraction. Using two specific inhibitors of MAPK, we could show a reduced LDLr expression in early-passage fibroblasts, indicating a direct relationship between MAPK signaling and LDLr expression. We conclude that one of the reasons for reduced LDLr gene expression in late passage fibroblast is related to MAPK signaling.

  17. Genetic Analysis of Gravity Signal Transduction in Arabidopsis thaliana Seedlings

    NASA Astrophysics Data System (ADS)

    Boonsirichai, K.; Harrison, B.; Stanga, J.; Young, L.-S.; Neal, C.; Sabat, G.; Murthy, N.; Harms, A.; Sedbrook, J.; Masson, P.

    The primary roots of Arabidopsis thaliana seedlings respond to gravity stimulation by developing a tip curvature that results from differential cellular elongation on opposite flanks of the elongation zone. This curvature appears modulated by a lateral gradient of auxin that originates in the gravity-perceiving cells (statocytes) of the root cap through an apparent lateral repositioning of a component the auxin efflux carrier complex within these cells (Friml et al, 2002, Nature 415: 806-809). Unfortunately, little is known about the molecular mechanisms that govern early phases of gravity perception and signal transduction within the root-cap statocytes. We have used a molecular genetic approach to uncover some of these mechanisms. Mutations in the Arabidopsis ARG1 and ARL2 genes, which encode J-domain proteins, resulted in specific alterations in root and hypocotyl gravitropism, without pleiotropic phenotypes. Interestingly, ARG1 and ARL2 appear to function in the same genetic pathway. A combination of molecular genetic, biochemical and cell-biological approaches were used to demonstrate that ARG1 functions in early phases of gravity signal transduction within the root and hypocotyl statocytes, and is needed for efficient lateral auxin transport within the cap. The ARG1 protein is associated with components of the secretory and/or endosomal pathways, suggesting its role in the recycling of components of the auxin efflux carrier complex between plasma membrane and endosome (Boonsirichai et al, 2003, Plant Cell 15:2612-2625). Genetic modifiers of arg1-2 were isolated and shown to enhance the gravitropic defect of arg1-2, while resulting in little or no gravitropic defects in a wild type ARG1 background. A slight tendency for arg1-2;mar1-1 and arg1-2;mar2-1 double-mutant organs to display an opposite gravitropic response compared to wild type suggests that all three genes contribute to the interpretation of the gravity-vector information by seedling organs. The

  18. Influence of arsenate and arsenite on signal transduction pathways: an update.

    PubMed

    Druwe, Ingrid L; Vaillancourt, Richard R

    2010-08-01

    Arsenic has been a recognized contaminant and toxicant, as well as a medicinal compound throughout human history. Populations throughout the world are exposed to arsenic and these exposures have been associated with a number of human cancers. Not much is known about the role of arsenic as a human carcinogen and more recently its role in non-cancerous diseases, such as cardiovascular disease, hypertension and diabetes mellitus have been uncovered. The health effects associated with arsenic are numerous and the association between arsenic exposure and human disease has intensified the search for molecular mechanisms that describe the biological activity of arsenic in humans and leads to the aforementioned disease states. Arsenic poses a human health risk due in part to the regulation of cellular signal transduction pathways and over the last few decades, some cellular mechanisms that account for arsenic toxicity, as well as, signal transduction pathways have been discovered. However, given the ubiquitous nature of arsenic in the environment, making sense of all the data remains a challenge. This review will focus on our knowledge of signal transduction pathways that are regulated by arsenic.

  19. Influence of arsenate and arsenite on signal transduction pathways: an update

    PubMed Central

    Druwe, Ingrid L.

    2010-01-01

    Arsenic has been a recognized contaminant and toxicant, as well as a medicinal compound throughout human history. Populations throughout the world are exposed to arsenic and these exposures have been associated with a number of human cancers. Not much is known about the role of arsenic as a human carcinogen and more recently its role in non-cancerous diseases, such as cardiovascular disease, hypertension and diabetes mellitus have been uncovered. The health effects associated with arsenic are numerous and the association between arsenic exposure and human disease has intensified the search for molecular mechanisms that describe the biological activity of arsenic in humans and leads to the aforementioned disease states. Arsenic poses a human health risk due in part to the regulation of cellular signal transduction pathways and over the last few decades, some cellular mechanisms that account for arsenic toxicity, as well as, signal transduction pathways have been discovered. However, given the ubiquitous nature of arsenic in the environment, making sense of all the data remains a challenge. This review will focus on our knowledge of signal transduction pathways that are regulated by arsenic. PMID:20502880

  20. The emerging role of phosphoinositide clustering in intracellular trafficking and signal transduction

    PubMed Central

    Picas, Laura; Gaits-Iacovoni, Frederique; Goud, Bruno

    2016-01-01

    Phosphoinositides are master regulators of multiple cellular processes: from vesicular trafficking to signaling, cytoskeleton dynamics, and cell growth. They are synthesized by the spatiotemporal regulated activity of phosphoinositide-metabolizing enzymes. The recent observation that some protein modules are able to cluster phosphoinositides suggests that alternative or complementary mechanisms might operate to stabilize the different phosphoinositide pools within cellular compartments. Herein, we discuss the different known and potential molecular players that are prone to engage phosphoinositide clustering and elaborate on how such a mechanism might take part in the regulation of intracellular trafficking and signal transduction. PMID:27092250

  1. Signal Transduction at the Single-Cell Level: Approaches to Study the Dynamic Nature of Signaling Networks.

    PubMed

    Handly, L Naomi; Yao, Jason; Wollman, Roy

    2016-09-25

    Signal transduction, or how cells interpret and react to external events, is a fundamental aspect of cellular function. Traditional study of signal transduction pathways involves mapping cellular signaling pathways at the population level. However, population-averaged readouts do not adequately illuminate the complex dynamics and heterogeneous responses found at the single-cell level. Recent technological advances that observe cellular response, computationally model signaling pathways, and experimentally manipulate cells now enable studying signal transduction at the single-cell level. These studies will enable deeper insights into the dynamic nature of signaling networks.

  2. Signal transduction meets vesicle traffic: the software and hardware of GLUT4 translocation.

    PubMed

    Klip, Amira; Sun, Yi; Chiu, Tim Ting; Foley, Kevin P

    2014-05-15

    Skeletal muscle is the major tissue disposing of dietary glucose, a function regulated by insulin-elicited signals that impart mobilization of GLUT4 glucose transporters to the plasma membrane. This phenomenon, also central to adipocyte biology, has been the subject of intense and productive research for decades. We focus on muscle cell studies scrutinizing insulin signals and vesicle traffic in a spatiotemporal manner. Using the analogy of an integrated circuit to approach the intersection between signal transduction and vesicle mobilization, we identify signaling relays ("software") that engage structural/mechanical elements ("hardware") to enact the rapid mobilization and incorporation of GLUT4 into the cell surface. We emphasize how insulin signal transduction switches from tyrosine through lipid and serine phosphorylation down to activation of small G proteins of the Rab and Rho families, describe key negative regulation step of Rab GTPases through the GTPase-activating protein activity of the Akt substrate of 160 kDa (AS160), and focus on the mechanical effectors engaged by Rabs 8A and 10 (the molecular motor myosin Va), and the Rho GTPase Rac1 (actin filament branching and severing through Arp2/3 and cofilin). Finally, we illustrate how actin filaments interact with myosin 1c and α-Actinin4 to promote vesicle tethering as preamble to fusion with the membrane.

  3. FIST: a sensory domain for diverse signal transduction pathways in prokaryotes and ubiquitin signaling in eukaryotes

    SciTech Connect

    Borziak, Kirill; Jouline, Igor B

    2007-01-01

    Motivation: Sensory domains that are conserved among Bacteria, Archaea and Eucarya are important detectors of common signals detected by living cells. Due to their high sequence divergence, sensory domains are difficult to identify. We systematically look for novel sensory domains using sensitive profile-based searches initi-ated with regions of signal transduction proteins where no known domains can be identified by current domain models. Results: Using profile searches followed by multiple sequence alignment, structure prediction, and domain architecture analysis, we have identified a novel sensory domain termed FIST, which is present in signal transduction proteins from Bacteria, Archaea and Eucarya. Remote similarity to a known ligand-binding fold and chromosomal proximity of FIST-encoding genes to those coding for proteins involved in amino acid metabolism and transport suggest that FIST domains bind small ligands, such as amino acids.

  4. FIST: a sensory domain for diverse signal transduction pathways in prokaryotes and ubiquitin signaling in eukaryotes

    PubMed Central

    Borziak, Kirill

    2016-01-01

    Motivation Sensory domains that are conserved among Bacteria, Archaea and Eucarya are important detectors of common signals detected by living cells. Due to their high sequence divergence, sensory domains are difficult to identify. We systematically look for novel sensory domains using sensitive profile-based searches initiated with regions of signal transduction proteins where no known domains can be identified by current domain models. Results Using profile searches followed by multiple sequence alignment, structure prediction and domain architecture analysis, we have identified a novel sensory domain termed FIST, which is present in signal transduction proteins from Bacteria, Archaea and Eucarya. Chromosomal proximity of FIST-encoding genes to those coding for proteins involved in amino acid metabolism and transport suggest that FIST domains bind small ligands, such as amino acids. PMID:17855421

  5. Effects of arsenite in astrocytes on neuronal signaling transduction.

    PubMed

    Wang, Yan; Zhao, Fenghong; Liao, Yingjun; Jin, Yaping; Sun, Guifan

    2013-01-01

    The main purpose of this study was to test the hypothesis that arsenite induces neurotoxicity via effects on astrocytes. Astrocytes were exposed to 0, 5 or 10 μM arsenite in medium for 24 h, and then astrocyte-conditioned medium (ACM) was collected after incubation with fresh medium for 6 h. Primary neuron cultures were divided into four groups due to ACM, which were neurons without ACM exposure (group I) and neurons exposed to ACM from 0, 5 or 10 μM arsenite treated astrocytes (group II-IV). Protein expression of N-methyl-d-aspartate receptors (NR1, NR2A, NR2B), calmodulin-dependent protein kinase II (CaMKII) and adenylate cyclase (AC) in neurons were measured after incubation with ACM for 4, 8 or 12 h. Morphological changes and synaptic formation were observed after a 72 h-incubation with ACM. Compared to group II, synaptic formation and protein expression of NR2A, NR2B, CaMKII and AC in group III and IV were significantly suppressed. Moreover, synaptic formation and protein expression of CaMKII and AC in group II were significantly enhanced when compared with group I. Taken together, findings from this study suggested that arsenic in astrocytes might impair synaptic formation through disturbing astrocytic effects on neuronal signal transduction.

  6. Impaired phospholipid-related signal transduction in advanced Huntington's disease.

    PubMed

    Puri, B K

    2001-09-01

    The aim of this study was to test the hypothesis that Huntington's disease is associated with impaired phospholipid-related signal transduction using the niacin skin flush test. This is the first reported use of this test in this patient group. The response to topical aqueous methyl nicotinate solution was recorded at 5 min intervals over 20 min in six in-patients with advanced (stage III) Huntington's disease and in 14 age- and sex-matched normal individuals with no history of this or any other major neurological disorder. The volumetric niacin response (VNR) (mean +/- S.E.M.) in the patients with Huntington's disease, 16.3 +/- 2.6 mol x s x l(-1), was significantly lower than the mean VNR of 28.3 +/- 2.1 mol x s x l(-1) in the control group (P = 0.004). These results are consistent with the conclusion that Huntington's disease may be associated with an abnormality of neuronal membrane fatty acid metabolism, possibly as a consequence of an as yet unidentified action of huntingtin.

  7. Signal transduction in cells of the immune system in microgravity

    PubMed Central

    Ullrich, Oliver; Huber, Kathrin; Lang, Kerstin

    2008-01-01

    Life on Earth developed in the presence and under the constant influence of gravity. Gravity has been present during the entire evolution, from the first organic molecule to mammals and humans. Modern research revealed clearly that gravity is important, probably indispensable for the function of living systems, from unicellular organisms to men. Thus, gravity research is no more or less a fundamental question about the conditions of life on Earth. Since the first space missions and supported thereafter by a multitude of space and ground-based experiments, it is well known that immune cell function is severely suppressed in microgravity, which renders the cells of the immune system an ideal model organism to investigate the influence of gravity on the cellular and molecular level. Here we review the current knowledge about the question, if and how cellular signal transduction depends on the existence of gravity, with special focus on cells of the immune system. Since immune cell function is fundamental to keep the organism under imnological surveillance during the defence against pathogens, to investigate the effects and possible molecular mechanisms of altered gravity is indispensable for long-term space flights to Earth Moon or Mars. Thus, understanding the impact of gravity on cellular functions on Earth will provide not only important informations about the development of life on Earth, but also for therapeutic and preventive strategies to cope successfully with medical problems during space exploration. PMID:18957108

  8. IGF-IR Signal Transduction Protein Content and Its Activation by IGF-I in Human Placentas: Relationship with Gestational Age and Birth Weight

    PubMed Central

    Iñiguez, Germán; Castro, Juan José; Garcia, Mirna; Kakarieka, Elena; Johnson, M. Cecilia; Cassorla, Fernando; Mericq, Verónica

    2014-01-01

    Introduction The human placenta expresses the IGF-I and IGF-IR proteins and their intracellular signal components (IRS-1, AKT and mTOR). The aim of this study was to assess the IGF-IR content and activation of downstream signaling molecules in placentas from newborns who were classified by gestational age and birth weight. We studied placentas from 25 term appropriate (T-AGA), 26 term small (T-SGA), 22 preterm AGA (PT-AGA), and 20 preterm SGA (PT-SGA) newborns. The total and phosphorylated IGF-IR, IRS-1, AKT, and mTOR contents were determined by Western Blot and normalized by actin or with their respective total content. The effect of IGF-I was determined by stimulating placental explants with recombinant IGF-I 10-8 mol/L for 15, 30, and 60 minutes. Results The IGF-IR content was higher in T-SGA compared to T-AGA placentas, and the IRS-1 content was higher in PT-placentas compared with their respective T-placentas. The effect of IGF-I on the phosphorylated forms of IGF-IR was increased in T-SGA (150%) and PT-SGA (300%) compared with their respective AGA placentas. In addition, AKT serine phosphorylation was higher in PT-SGA compared to PT-AGA and T-SGA placentas (90% and 390% respectively). Conclusion The higher protein content and response to IGF-I of IGF-IR, IRS-1, and AKT observed in SGA placentas may represent a compensatory mechanism in response to fetal growth restriction. PMID:25050889

  9. Membrane-lipid therapy in operation: the HSP co-inducer BGP-15 activates stress signal transduction pathways by remodeling plasma membrane rafts.

    PubMed

    Gombos, Imre; Crul, Tim; Piotto, Stefano; Güngör, Burcin; Török, Zsolt; Balogh, Gábor; Péter, Mária; Slotte, J Peter; Campana, Federica; Pilbat, Ana-Maria; Hunya, Akos; Tóth, Noémi; Literati-Nagy, Zsuzsanna; Vígh, László; Glatz, Attila; Brameshuber, Mario; Schütz, Gerhard J; Hevener, Andrea; Febbraio, Mark A; Horváth, Ibolya; Vígh, László

    2011-01-01

    Aging and pathophysiological conditions are linked to membrane changes which modulate membrane-controlled molecular switches, causing dysregulated heat shock protein (HSP) expression. HSP co-inducer hydroxylamines such as BGP-15 provide advanced therapeutic candidates for many diseases since they preferentially affect stressed cells and are unlikely have major side effects. In the present study in vitro molecular dynamic simulation, experiments with lipid monolayers and in vivo ultrasensitive fluorescence microscopy showed that BGP-15 alters the organization of cholesterol-rich membrane domains. Imaging of nanoscopic long-lived platforms using the raft marker glycosylphosphatidylinositol-anchored monomeric green fluorescent protein diffusing in the live Chinese hamster ovary (CHO) cell plasma membrane demonstrated that BGP-15 prevents the transient structural disintegration of rafts induced by fever-type heat stress. Moreover, BGP-15 was able to remodel cholesterol-enriched lipid platforms reminiscent of those observed earlier following non-lethal heat priming or membrane stress, and were shown to be obligate for the generation and transmission of stress signals. BGP-15 activation of HSP expression in B16-F10 mouse melanoma cells involves the Rac1 signaling cascade in accordance with the previous observation that cholesterol affects the targeting of Rac1 to membranes. Finally, in a human embryonic kidney cell line we demonstrate that BGP-15 is able to inhibit the rapid heat shock factor 1 (HSF1) acetylation monitored during the early phase of heat stress, thereby promoting a prolonged duration of HSF1 binding to heat shock elements. Taken together, our results indicate that BGP-15 has the potential to become a new class of pharmaceuticals for use in 'membrane-lipid therapy' to combat many various protein-misfolding diseases associated with aging.

  10. Lipopolysaccharide enhances bradykinin-induced signal transduction via activation of Ras/Raf/MEK/MAPK in canine tracheal smooth muscle cells

    PubMed Central

    Luo, Shue-Fen; Wang, Chuan-Chwan; Chiu, Chi-Tso; Chien, Chin-Sung; Hsiao, Li-Der; Lin, Chien-Huang; Yang, Chuen-Mao

    2000-01-01

    Bacterial lipopolysaccharide (LPS) was found to induce inflammatory responses and to enhance bronchial hyperreactivity to several contractile agonists. However, the implication of LPS in the pathogenesis of bronchial hyperreactivity was not completely understood. Therefore, in this study, we investigated the effect of LPS on mitogen-activated protein kinase (MAPK) activation associated with potentiation of bradykinin (BK)-induced inositol phosphates (IPs) accumulation and Ca2+ mobilization in canine cultured tracheal smooth muscle cells (TSMCs).LPS stimulated phosphorylation of p42/p44 MAPK in a time- and concentration-dependent manner using a Western blot analysis against a specific phosphorylated form of MAPK antibody. Maximal stimulation of the p42 and p44 MAPK isoforms occurred after 7 min-incubation and the maximal effect was achieved with 100 μg ml−1 LPS.Pretreatment of TSMCs with LPS potentiated BK-induced IPs accumulation and Ca2+ mobilization. However, there was no effect on the IPs response induced by endothelin-1, 5-hydroxytryptamine, and carbachol. In addition, pretreatment with PDGF-BB enhanced BK-induced IPs response.These enhancements by LPS and PDGF-BB might be due to an increase in BK B2 receptor density (Bmax) in TSMCs, characterized by competitive inhibition of [3H]-BK binding using B1 and B2 receptor-selective reagents.The enhancing effects of LPS and PDGF-BB were attenuated by PD98059, an inhibitor of MAPK kinase (MEK), suggesting that the effect of LPS may share a common signalling pathway with PDGF-BB in TSMCs.Furthermore, overexpression of dominant negative mutants, H-Ras-15A and Raf-N4, significantly suppressed p42/p44 MAPK activation induced by LPS and PDGF-BB, indicating that Ras and Raf may be required for activation of these kinases.These results suggest that the augmentation of BK-induced responses produced by LPS might be, at least in part, mediated through activation of Ras/Raf/MEK/MAPK pathway in TSMCs. PMID:10952668

  11. Matricellular signal transduction involving calmodulin in the social amoebozoan dictyostelium.

    PubMed

    O'Day, Danton H; Huber, Robert J

    2013-01-01

    The social amoebozoan Dictyostelium discoideum undergoes a developmental sequence wherein an extracellular matrix (ECM) sheath surrounds a group of differentiating cells. This sheath is comprised of proteins and carbohydrates, like the ECM of mammalian tissues. One of the characterized ECM proteins is the cysteine-rich, EGF-like (EGFL) repeat-containing, calmodulin (CaM)-binding protein (CaMBP) CyrA. The first EGFL repeat of CyrA increases the rate of random cell motility and cyclic AMP-mediated chemotaxis. Processing of full-length CyrA (~63 kDa) releases two major EGFL repeat-containing fragments (~45 kDa and ~40 kDa) in an event that is developmentally regulated. Evidence for an EGFL repeat receptor also exists and downstream intracellular signaling pathways involving CaM, Ras, protein kinase A and vinculin B phosphorylation have been characterized. In total, these results identify CyrA as a true matricellular protein comparable in function to tenascin C and other matricellular proteins from mammalian cells. Insight into the regulation and processing of CyrA has also been revealed. CyrA is the first identified extracellular CaMBP in this eukaryotic microbe. In keeping with this, extracellular CaM (extCaM) has been shown to be present in the ECM sheath where it binds to CyrA and inhibits its cleavage to release the 45 kDa and 40 kDa EGFL repeat-containing fragments. The presence of extCaM and its role in regulating a matricellular protein during morphogenesis extends our understanding of CaM-mediated signal transduction in eukaryotes. PMID:24705101

  12. Matricellular signal transduction involving calmodulin in the social amoebozoan dictyostelium.

    PubMed

    O'Day, Danton H; Huber, Robert J

    2013-02-15

    The social amoebozoan Dictyostelium discoideum undergoes a developmental sequence wherein an extracellular matrix (ECM) sheath surrounds a group of differentiating cells. This sheath is comprised of proteins and carbohydrates, like the ECM of mammalian tissues. One of the characterized ECM proteins is the cysteine-rich, EGF-like (EGFL) repeat-containing, calmodulin (CaM)-binding protein (CaMBP) CyrA. The first EGFL repeat of CyrA increases the rate of random cell motility and cyclic AMP-mediated chemotaxis. Processing of full-length CyrA (~63 kDa) releases two major EGFL repeat-containing fragments (~45 kDa and ~40 kDa) in an event that is developmentally regulated. Evidence for an EGFL repeat receptor also exists and downstream intracellular signaling pathways involving CaM, Ras, protein kinase A and vinculin B phosphorylation have been characterized. In total, these results identify CyrA as a true matricellular protein comparable in function to tenascin C and other matricellular proteins from mammalian cells. Insight into the regulation and processing of CyrA has also been revealed. CyrA is the first identified extracellular CaMBP in this eukaryotic microbe. In keeping with this, extracellular CaM (extCaM) has been shown to be present in the ECM sheath where it binds to CyrA and inhibits its cleavage to release the 45 kDa and 40 kDa EGFL repeat-containing fragments. The presence of extCaM and its role in regulating a matricellular protein during morphogenesis extends our understanding of CaM-mediated signal transduction in eukaryotes.

  13. A third secreted protein that is encoded by the enteropathogenic Escherichia coli pathogenicity island is required for transduction of signals and for attaching and effacing activities in host cells.

    PubMed Central

    Lai, L C; Wainwright, L A; Stone, K D; Donnenberg, M S

    1997-01-01

    Enteropathogenic Escherichia coli strains are able to signal host cells, cause dramatic cytoskeletal rearrangements, and adhere intimately to the cell surface in a process known as the attaching and effacing effect. A pathogenicity island of 35 kb known as the locus of enterocyte effacement (LEE) is necessary and sufficient for this effect. The LEE encodes an outer membrane adhesin called intimin, a type III secretion apparatus, and the EspA and EspB secreted proteins. The DNA sequence of the region between espA and espB revealed a new gene, espD. The product of espD was demonstrated by using a T7 expression system. We constructed a nonpolar mutation in espD and found that the mutant is incapable of the signal transduction events that lead to activation of the putative intimin receptor in host cells and that the mutant fails to induce the attaching and effacing effect. These phenotypes were restored to the mutant by complementation with a plasmid containing the cloned espD locus. We demonstrated by immunoblotting and microsequencing that the EspD protein is secreted via the type III apparatus. Thus, we describe a novel locus encoding a secreted protein that is required for attaching and effacing activity. PMID:9169753

  14. New Signal Transduction Principles for Amperometric Enzyme and Antibody based Sensors

    NASA Astrophysics Data System (ADS)

    Warsinke, Axel

    2008-10-01

    The way of how the signal transfer from the analyte recognizing biocomponent to the sensor surface is performed influences strongly the characteristics of a biosensor e.g. response time, sensitivity and specificity. Most of the described amperometric enzyme sensors are using oxidases. The signal transduction is carried out simply by electrochemical indication of the produced hydrogen peroxide or via a sensor-immobilized redox polymer. However, due to the limited number of appropriate oxidases the range of detectable analytes is restricted. Hence, we have developed a new general principle for the sensitive transduction of the more than 400 different NAD(P) dependent dehydrogenase reactions. The transduction is based on a hydroxylase reaction which produces an electrochemically active substance under the consumption of NAD(P)H. The principle should be applicable to miniaturized sensor configuration and could be the basis for a new generation of point-of-care devices. For other analytes where no oxidases and dehydrogenases are available antibodies can be used as specific recognition element. We have developed a new principle of redox-labeled immunoassays called size exclusion redox-labeled immunoassay (SERI), where after the antigen antibody binding reaction the indication is carried out amperometrically without a washing step in between. The principle was proved for measurement of creatinine. At the moment the assay needs a relatively high amount of antibodies. However, in future it should be possible to reduce the amount of antibodies by using miniaturized microfluidic chips.

  15. An integrated signal transduction network of macrophage migration inhibitory factor.

    PubMed

    Subbannayya, Tejaswini; Variar, Prathyaksha; Advani, Jayshree; Nair, Bipin; Shankar, Subramanian; Gowda, Harsha; Saussez, Sven; Chatterjee, Aditi; Prasad, T S Keshava

    2016-06-01

    Macrophage migration inhibitory factor (MIF) is a glycosylated multi-functional protein that acts as an enzyme as well as a cytokine. MIF mediates its actions through a cell surface class II major histocompatibility chaperone, CD74 and co-receptors such as CD44, CXCR2, CXCR4 or CXCR7. MIF has been implicated in the pathogenesis of several acute and chronic inflammatory diseases. Although MIF is a molecule of biomedical importance, a public resource of MIF signaling pathway is currently lacking. In view of this, we carried out detailed data mining and documentation of the signaling events pertaining to MIF from published literature and developed an integrated reaction map of MIF signaling. This resulted in the cataloguing of 68 molecules belonging to MIF signaling pathway, which includes 24 protein-protein interactions, 44 post-translational modifications, 11 protein translocation events and 8 activation/inhibition events. In addition, 65 gene regulation events at the mRNA levels induced by MIF signaling have also been catalogued. This signaling pathway has been integrated into NetPath ( http://www.netpath.org ), a freely available human signaling pathway resource developed previously by our group. The MIF pathway data is freely available online in various community standard data exchange formats. We expect that data on signaling events and a detailed signaling map of MIF will provide the scientific community with an improved platform to facilitate further molecular as well as biomedical investigations on MIF. PMID:27139435

  16. Structural mechanism for signal transduction in RXR nuclear receptor heterodimers

    PubMed Central

    Kojetin, Douglas J.; Matta-Camacho, Edna; Hughes, Travis S.; Srinivasan, Sathish; Nwachukwu, Jerome C.; Cavett, Valerie; Nowak, Jason; Chalmers, Michael J.; Marciano, David P.; Kamenecka, Theodore M.; Shulman, Andrew I.; Rance, Mark; Griffin, Patrick R.; Bruning, John B.; Nettles, Kendall W.

    2015-01-01

    A subset of nuclear receptors (NRs) function as obligate heterodimers with retinoid X receptor (RXR), allowing integration of ligand-dependent signals across the dimer interface via an unknown structural mechanism. Using nuclear magnetic resonance (NMR) spectroscopy, x-ray crystallography and hydrogen/deuterium exchange (HDX) mass spectrometry, here we show an allosteric mechanism through which RXR co-operates with a permissive dimer partner, peroxisome proliferator-activated receptor (PPAR)-γ, while rendered generally unresponsive by a non-permissive dimer partner, thyroid hormone (TR) receptor. Amino acid residues that mediate this allosteric mechanism comprise an evolutionarily conserved network discovered by statistical coupling analysis (SCA). This SCA network acts as a signalling rheostat to integrate signals between dimer partners, ligands and coregulator-binding sites, thereby affecting signal transmission in RXR heterodimers. These findings define rules guiding how NRs integrate two ligand-dependent signalling pathways into RXR heterodimer-specific responses. PMID:26289479

  17. New insights into the organization of plasma membrane and its role in signal transduction.

    PubMed

    Suzuki, Kenichi G N

    2015-01-01

    Plasma membranes have heterogeneous structures for efficient signal transduction, required to perform cell functions. Recent evidence indicates that the heterogeneous structures are produced by (1) compartmentalization by actin-based membrane skeleton, (2) raft domains, (3) receptor-receptor interactions, and (4) the binding of receptors to cytoskeletal proteins. This chapter provides an overview of recent studies on diffusion, clustering, raft association, actin binding, and signal transduction of membrane receptors, especially glycosylphosphatidylinositol (GPI)-anchored receptors. Studies on diffusion of GPI-anchored receptors suggest that rafts may be small and/or short-lived in plasma membranes. In steady state conditions, GPI-anchored receptors form transient homodimers, which may represent the "standby state" for the stable homodimers and oligomers upon ligation. Furthermore, It is proposed that upon ligation, the binding of GPI-anchored receptor clusters to cytoskeletal actin filaments produces a platform for downstream signaling, and that the pulse-like signaling easily maintains the stability of the overall signaling activity.

  18. Identification of specific gravity sensitive signal transduction pathways in human A431 carcinoma cells

    NASA Astrophysics Data System (ADS)

    Rijken, P. J.; de Groot, R. P.; Kruijer, W.; de Laat, S. W.; Verkleij, A. J.; Boonstra, J.

    Epidermal growth factor (EGF) activates a well characterized signal transduction cascade in human A431 epidermoid carcinoma cells. The influence of gravity on EGF-induced EGF-receptor clustering and early gene expression as well as on actin polymerization and actin organization have been investigated. Different signalling pathways induced by the agents TPA, forskolin and A23187 that activate gene expression were tested for sensitivity to gravity. EGF-induced c-fos and c-jun expression were decreased in microgravity. However, constitutive β-2 microglobulin expression remained unaltered. Under simulated weightlessness conditions EGF- and TPA-induced c-fos expression was decreased, while forskolin- and A23187-induced c-fos expression was independent of the gravity conditions. These results suggest that gravity affects specific signalling pathways. Preliminary results indicate that EGF-induced EGF-receptor clustering remained unaltered irrespective of the gravity conditions. Furthermore, the relative filamentous actin content of steady state A431 cells was enhanced under microgravity conditions and actin filament organization was altered. Under simulated weightlessness actin filament organization in steady state cells as well as in EGF-treated cells was altered as compared to the 1 G reference experiment. Interestingly the microtubule and keratin organization in untreated cells showed no difference with the normal gravity samples. This indicates that gravity may affect specific components of the signal transduction circuitry.

  19. Second-Chance Signal Transduction Explains Cooperative Flagellar Switching

    PubMed Central

    Zot, Henry G.; Hasbun, Javier E.; Van Minh, Nguyen

    2012-01-01

    The reversal of flagellar motion (switching) results from the interaction between a switch complex of the flagellar rotor and a torque-generating stationary unit, or stator (motor unit). To explain the steeply cooperative ligand-induced switching, present models propose allosteric interactions between subunits of the rotor, but do not address the possibility of a reaction that stimulates a bidirectional motor unit to reverse direction of torque. During flagellar motion, the binding of a ligand-bound switch complex at the dwell site could excite a motor unit. The probability that another switch complex of the rotor, moving according to steady-state rotation, will reach the same dwell site before that motor unit returns to ground state will be determined by the independent decay rate of the excited-state motor unit. Here, we derive an analytical expression for the energy coupling between a switch complex and a motor unit of the stator complex of a flagellum, and demonstrate that this model accounts for the cooperative switching response without the need for allosteric interactions. The analytical result can be reproduced by simulation when (1) the motion of the rotor delivers a subsequent ligand-bound switch to the excited motor unit, thereby providing the excited motor unit with a second chance to remain excited, and (2) the outputs from multiple independent motor units are constrained to a single all-or-none event. In this proposed model, a motor unit and switch complex represent the components of a mathematically defined signal transduction mechanism in which energy coupling is driven by steady-state and is regulated by stochastic ligand binding. Mathematical derivation of the model shows the analytical function to be a general form of the Hill equation (Hill AV (1910) The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves. J Physiol 40: iv–vii). PMID:22844429

  20. A bead-based western for high-throughput cellular signal transduction analyses

    PubMed Central

    Treindl, Fridolin; Ruprecht, Benjamin; Beiter, Yvonne; Schultz, Silke; Döttinger, Anette; Staebler, Annette; Joos, Thomas O.; Kling, Simon; Poetz, Oliver; Fehm, Tanja; Neubauer, Hans; Kuster, Bernhard; Templin, Markus F.

    2016-01-01

    Dissecting cellular signalling requires the analysis of large number of proteins. The DigiWest approach we describe here transfers the western blot to a bead-based microarray platform. By combining gel-based protein separation with immobilization on microspheres, hundreds of replicas of the initial blot are created, thus enabling the comprehensive analysis of limited material, such as cells collected by laser capture microdissection, and extending traditional western blotting to reach proteomic scales. The combination of molecular weight resolution, sensitivity and signal linearity on an automated platform enables the rapid quantification of hundreds of specific proteins and protein modifications in complex samples. This high-throughput western blot approach allowed us to identify and characterize alterations in cellular signal transduction that occur during the development of resistance to the kinase inhibitor Lapatinib, revealing major changes in the activation state of Ephrin-mediated signalling and a central role for p53-controlled processes. PMID:27659302

  1. Fas- and tumor necrosis factor-mediated apoptosis uses the same binding surface of FADD to trigger signal transduction. A typical model for convergent signal transduction.

    PubMed

    Bang, S; Jeong, E J; Kim, I K; Jung, Y K; Kim, K S

    2000-11-17

    FADD is known to function as a common signaling conduit in Fas- and tumor necrosis factor (TNF)-mediated apoptosis. The convergent death signals from the Fas receptor and TNF receptor 1 are transferred to FADD by death domain interactions triggering the same cellular event, caspase-8 activation. In this work, we investigated whether the same binding surface of FADD is used for both signaling pathways by using FADD death domain mutants. Mutations in helices alpha2 and alpha3 of the FADD death domain, the interacting surface with the Fas death domain, affected TNF-mediated apoptosis to various extents. This indicated that TNF-mediated apoptosis uses the same binding surface of the FADD death domain as Fas-mediated apoptosis. The binding specificity is not the same, however. Some mutations affected the binding affinity of the Fas death domain for the FADD death domain, but did not influence TNF-mediated apoptosis and vice versa. Interestingly, all mutants tested that affected TNF-mediated apoptosis have structural perturbations, implying that the structural integrity, involving helices alpha2 and alpha3 in particular, is critical in TNF-mediated apoptosis. Our results suggest that different signaling molecules use a similar structural interaction to trigger the same cellular event, such as caspase-8 recruitment, which could be typical in convergent signal transduction.

  2. Modeling Signal Transduction Networks: A comparison of two Stochastic Kinetic Simulation Algorithms

    SciTech Connect

    Pettigrew, Michel F.; Resat, Haluk

    2005-09-15

    Simulations of a scalable four compartment reaction model based on the well known epidermal growth factor receptor (EGFR) signal transduction system are used to compare two stochastic algorithms ? StochSim and the Gibson-Gillespie. It is concluded that the Gibson-Gillespie is the algorithm of choice for most realistic cases with the possible exception of signal transduction networks characterized by a moderate number (< 100) of complex types, each with a very small population, but with a high degree of connectivity amongst the complex types. Keywords: Signal transduction networks, Stochastic simulation, StochSim, Gillespie

  3. HAMP domain-mediated signal transduction probed with a mycobacterial adenylyl cyclase as a reporter.

    PubMed

    Mondéjar, Laura García; Lupas, Andrei; Schultz, Anita; Schultz, Joachim E

    2012-01-01

    HAMP domains, ∼55 amino acid motifs first identified in histidine kinases, adenylyl cyclases, methyl-accepting chemotaxis proteins, and phosphatases, operate as signal mediators in two-component signal transduction proteins. A bioinformatics study identified a coevolving signal-accepting network of 10 amino acids in membrane-delimited HAMP proteins. To probe the functionality of this network we used a HAMP containing mycobacterial adenylyl cyclase, Rv3645, as a reporter enzyme in which the membrane anchor was substituted by the Escherichia coli chemotaxis receptor for serine (Tsr receptor) and the HAMP domain alternately with that from the protein Af1503 of the archaeon Archaeoglobus fulgidus or the Tsr receptor. In a construct with the Tsr-HAMP, cyclase activity was inhibited by serine, whereas in a construct with the HAMP domain from A. fulgidus, enzyme activity was not responsive to serine. Amino acids of the signal-accepting network were mutually swapped between both HAMP domains, and serine signaling was examined. The data biochemically tentatively established the functionality of the signal-accepting network. Based on a two-state gearbox model of rotation in HAMP domain-mediated signal propagation, we characterized the interaction between permanent and transient core residues in a coiled coil HAMP structure. The data are compatible with HAMP rotation in signal propagation but do not exclude alternative models for HAMP signaling. Finally, we present data indicating that the connector, which links the α-helices of HAMP domains, plays an important structural role in HAMP function.

  4. T cell Receptor Signal Transduction in T lymphocytes

    PubMed Central

    Gorentla, Balachandra K; Zhong, Xiao-Ping

    2012-01-01

    The T cell receptor (TCR) recognizes self or foreign antigens presented by major histocompatibility complex (MHC) molecules. Engagement of the TCR triggers the formation of multi-molecular signalosomes that lead to the generation of second messengers and subsequent activation of multiple distal signaling cascades, such as the Ca+2-calcineurin-NFAT, RasGRP1-Ras-Erk1/2, PKCθ-IKK-NFκB, and TSC1/2-mTOR pathways. These signaling cascades control many aspects of T cell biology. Mechanisms have been evolved to fine-tune TCR signaling to maintain T cell homeostasis and self-tolerance, and to properly mount effective responses to microbial infection. Defects or deregulation of TCR signaling has been implicated in the pathogenesis of multiple human diseases. PMID:23946894

  5. Signal Transduction by BvgS Sensor Kinase

    PubMed Central

    Dupré, Elian; Lesne, Elodie; Guérin, Jérémy; Lensink, Marc F.; Verger, Alexis; de Ruyck, Jérôme; Brysbaert, Guillaume; Vezin, Hervé; Locht, Camille; Antoine, Rudy; Jacob-Dubuisson, Françoise

    2015-01-01

    The two-component sensory transduction system BvgAS controls the virulence regulon of the whooping-cough agent Bordetella pertussis. The periplasmic moiety of the homodimeric sensor kinase BvgS is composed of four bilobed Venus flytrap (VFT) perception domains followed by α helices that extend into the cytoplasmic membrane. In the virulent phase, the default state of B. pertussis, the cytoplasmic enzymatic moiety of BvgS acts as kinase by autophosphorylating and transferring the phosphoryl group to the response regulator BvgA. Under laboratory conditions, BvgS shifts to phosphatase activity in response to modulators, notably nicotinate ions. Here we characterized the effects of nicotinate and related modulators on the BvgS periplasmic moiety by using site-directed mutagenesis and in silico and biophysical approaches. Modulators bind with low affinity to BvgS in the VFT2 cavity. Electron paramagnetic resonance shows that their binding globally affects the conformation and dynamics of the periplasmic moiety. Specific amino acid substitutions designed to slacken interactions within and between the VFT lobes prevent BvgS from responding to nicotinate, showing that BvgS shifts from kinase to phosphatase activity in response to this modulator via a tense transition state that involves a large periplasmic structural block. We propose that this transition enables the transmembrane helices to adopt a distinct conformation that sets the cytoplasmic enzymatic moiety in the phosphatase mode. The bona fide, in vivo VFT ligands that remain to be identified are likely to trigger similar effects on the transmembrane and cytoplasmic moieties. This mechanism may be relevant to the other VFT-containing sensor kinases homologous to BvgS. PMID:26203186

  6. Transmembrane signal transduction by peptide hormones via family B G protein-coupled receptors

    PubMed Central

    Culhane, Kelly J.; Liu, Yuting; Cai, Yingying; Yan, Elsa C. Y.

    2015-01-01

    Although family B G protein-coupled receptors (GPCRs) contain only 15 members, they play key roles in transmembrane signal transduction of hormones. Family B GPCRs are drug targets for developing therapeutics for diseases ranging from metabolic to neurological disorders. Despite their importance, the molecular mechanism of activation of family B GPCRs remains largely unexplored due to the challenges in expression and purification of functional receptors to the quantity for biophysical characterization. Currently, there is no crystal structure available of a full-length family B GPCR. However, structures of key domains, including the extracellular ligand binding regions and seven-helical transmembrane regions, have been solved by X-ray crystallography and NMR, providing insights into the mechanisms of ligand recognition and selectivity, and helical arrangements within the cell membrane. Moreover, biophysical and biochemical methods have been used to explore functions, key residues for signaling, and the kinetics and dynamics of signaling processes. This review summarizes the current knowledge of the signal transduction mechanism of family B GPCRs at the molecular level and comments on the challenges and outlook for mechanistic studies of family B GPCRs. PMID:26594176

  7. Cellerator: extending a computer algebra system to include biochemical arrows for signal transduction simulations

    NASA Technical Reports Server (NTRS)

    Shapiro, Bruce E.; Levchenko, Andre; Meyerowitz, Elliot M.; Wold, Barbara J.; Mjolsness, Eric D.

    2003-01-01

    Cellerator describes single and multi-cellular signal transduction networks (STN) with a compact, optionally palette-driven, arrow-based notation to represent biochemical reactions and transcriptional activation. Multi-compartment systems are represented as graphs with STNs embedded in each node. Interactions include mass-action, enzymatic, allosteric and connectionist models. Reactions are translated into differential equations and can be solved numerically to generate predictive time courses or output as systems of equations that can be read by other programs. Cellerator simulations are fully extensible and portable to any operating system that supports Mathematica, and can be indefinitely nested within larger data structures to produce highly scaleable models.

  8. Dissecting Arabidopsis G beta signal transduction on the protein surface

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The heterotrimeric G protein complex provides signal amplification and target specificity. The Arabidopsis Gbeta subunit of this complex (AGB1) interacts with and modulates the activity of target cytoplasmic proteins. This specificity resides in the structure of the interface between AGB1 and its ta...

  9. Arm-in-Arm Response Regulator Dimers Promote Intermolecular Signal Transduction

    PubMed Central

    Baker, Anna W.; Satyshur, Kenneth A.; Moreno Morales, Neydis

    2016-01-01

    ABSTRACT Bacteriophytochrome photoreceptors (BphPs) and their cognate response regulators make up two-component signal transduction systems which direct bacteria to mount phenotypic responses to changes in environmental light quality. Most of these systems utilize single-domain response regulators to transduce signals through unknown pathways and mechanisms. Here we describe the photocycle and autophosphorylation kinetics of RtBphP1, a red light-regulated histidine kinase from the desert bacterium Ramlibacter tataouinensis. RtBphP1 undergoes red to far-red photoconversion with rapid thermal reversion to the dark state. RtBphP1 is autophosphorylated in the dark; this activity is inhibited under red light. The RtBphP1 cognate response regulator, the R. tataouinensis bacteriophytochrome response regulator (RtBRR), and a homolog, AtBRR from Agrobacterium tumefaciens, crystallize unexpectedly as arm-in-arm dimers, reliant on a conserved hydrophobic motif, hFWAhL (where h is a hydrophobic M, V, L, or I residue). RtBRR and AtBRR dimerize distinctly from four structurally characterized phytochrome response regulators found in photosynthetic organisms and from all other receiver domain homodimers in the Protein Data Bank. A unique cacodylate-zinc-histidine tag metal organic framework yielded single-wavelength anomalous diffraction phases and may be of general interest. Examination of the effect of the BRR stoichiometry on signal transduction showed that phosphorylated RtBRR is accumulated more efficiently than the engineered monomeric RtBRR (RtBRRmon) in phosphotransfer reactions. Thus, we conclude that arm-in-arm dimers are a relevant signaling intermediate in this class of two-component regulatory systems. IMPORTANCE BphP histidine kinases and their cognate response regulators comprise widespread red light-sensing two-component systems. Much work on BphPs has focused on structural understanding of light sensing and on enhancing the natural infrared fluorescence of these

  10. Coupling of signal transduction to alternative pre-mRNA splicing by a composite splice regulator.

    PubMed Central

    König, H; Ponta, H; Herrlich, P

    1998-01-01

    Alternative splicing of pre-mRNA is a fundamental mechanism of differential gene expression in that it can give rise to functionally distinct proteins from a single gene, according to the developmental or physiological state of cells in multicellular organisms. In the pre-mRNA of the cell surface molecule CD44, the inclusion of up to 10 variant exons (v1-v10) is regulated during development, upon activation of lymphocytes and dendritic cells, and during tumour progression. Using minigene constructs containing CD44 exon v5, we have discovered exonic RNA elements that couple signal transduction to alternative splicing. They form a composite splice regulator encompassing an exon recognition element and splice silencer elements. Both type of elements are necessary to govern cell type-specific inclusion of the exon as well as inducible inclusion in T cells after stimulation by concanavalin A, by Ras signalling or after activation of protein kinase C by phorbol ester. Inducible splicing does not depend on de novo protein synthesis. The coupling of signal transduction to alternative splicing by such elements probably represents the mechanism whereby splice patterns of genes are established during development and can be changed under physiological and pathological conditions. PMID:9582284

  11. Amyloid beta-peptide disrupts carbachol-induced muscarinic cholinergic signal transduction in cortical neurons.

    PubMed

    Kelly, J F; Furukawa, K; Barger, S W; Rengen, M R; Mark, R J; Blanc, E M; Roth, G S; Mattson, M P

    1996-06-25

    Cholinergic pathways serve important functions in learning and memory processes, and deficits in cholinergic transmission occur in Alzheimer disease (AD). A subset of muscarinic cholinergic receptors are linked to G-proteins that activate phospholipase C, resulting in the liberation of inositol trisphosphate and Ca2+ release from intracellular stores. We now report that amyloid beta-peptide (Abeta), which forms plaques in the brain in AD, impairs muscarinic receptor activation of G proteins in cultured rat cortical neurons. Exposure of rodent fetal cortical neurons to Abeta25-35 and Abeta1-40 resulted in a concentration and time-dependent attenuation of carbachol-induced GTPase activity without affecting muscarinic receptor ligand binding parameters. Downstream events in the signal transduction cascade were similarly attenuated by Abeta. Carbachol-induced accumulation of inositol phosphates (IP, IP2, IP3, and IP4) was decreased and calcium imaging studies revealed that carbachol-induced release of calcium was severely impaired in neurons pretreated with Abeta. Muscarinic cholinergic signal transduction was disrupted with subtoxic levels of exposure to AP. The effects of Abeta on carbachol-induced GTPase activity and calcium release were attenuated by antioxidants, implicating free radicals in the mechanism whereby Abeta induced uncoupling of muscarinic receptors. These data demonstrate that Abeta disrupts muscarinic receptor coupling to G proteins that mediate induction of phosphoinositide accumulation and calcium release, findings that implicate Abeta in the impairment of cholinergic transmission that occurs in AD. PMID:8692890

  12. The cellular response to vascular endothelial growth factors requires co-ordinated signal transduction, trafficking and proteolysis

    PubMed Central

    Smith, Gina A.; Fearnley, Gareth W.; Tomlinson, Darren C.; Harrison, Michael A.; Ponnambalam, Sreenivasan

    2015-01-01

    VEGFs (vascular endothelial growth factors) are a family of conserved disulfide-linked soluble secretory glycoproteins found in higher eukaryotes. VEGFs mediate a wide range of responses in different tissues including metabolic homoeostasis, cell proliferation, migration and tubulogenesis. Such responses are initiated by VEGF binding to soluble and membrane-bound VEGFRs (VEGF receptor tyrosine kinases) and co-receptors. VEGF and receptor splice isoform diversity further enhances complexity of membrane protein assembly and function in signal transduction pathways that control multiple cellular responses. Different signal transduction pathways are simultaneously activated by VEGFR–VEGF complexes with membrane trafficking along the endosome–lysosome network further modulating signal output from multiple enzymatic events associated with such pathways. Balancing VEGFR–VEGF signal transduction with trafficking and proteolysis is essential in controlling the intensity and duration of different intracellular signalling events. Dysfunction in VEGF-regulated signal transduction is important in chronic disease states including cancer, atherosclerosis and blindness. This family of growth factors and receptors is an important model system for understanding human disease pathology and developing new therapeutics for treating such ailments. PMID:26285805

  13. Sentra : a database of signal transduction proteins for comparative genome analysis.

    SciTech Connect

    D'Souza, M.; Glass, E. M.; Syed, M. H.; Zhang, Y.; Rodriguez, A.; Maltsev, N.; Galerpin, M. Y.; Mathematics and Computer Science; Univ. of Chicago; NIH

    2007-01-01

    Sentra (http://compbio.mcs.anl.gov/sentra), a database of signal transduction proteins encoded in completely sequenced prokaryotic genomes, has been updated to reflect recent advances in understanding signal transduction events on a whole-genome scale. Sentra consists of two principal components, a manually curated list of signal transduction proteins in 202 completely sequenced prokaryotic genomes and an automatically generated listing of predicted signaling proteins in 235 sequenced genomes that are awaiting manual curation. In addition to two-component histidine kinases and response regulators, the database now lists manually curated Ser/Thr/Tyr protein kinases and protein phosphatases, as well as adenylate and diguanylate cyclases and c-di-GMP phosphodiesterases, as defined in several recent reviews. All entries in Sentra are extensively annotated with relevant information from public databases (e.g. UniProt, KEGG, PDB and NCBI). Sentra's infrastructure was redesigned to support interactive cross-genome comparisons of signal transduction capabilities of prokaryotic organisms from a taxonomic and phenotypic perspective and in the framework of signal transduction pathways from KEGG. Sentra leverages the PUMA2 system to support interactive analysis and annotation of signal transduction proteins by the users.

  14. FASEB summer research conference on signal transduction in plants. Final report, June 16, 1996--June 21, 1996

    SciTech Connect

    Lomax, T.L.; Quatrano, R.S.

    1996-12-31

    This is the program from the second FASEB conference on Signal Transduction in Plants. Topic areas included the following: environmental signaling; perception and transduction of light signals; signaling in plant microbe interactions; signaling in plant pathogen interactions; cell, cell communication; cytoskeleton, plasma membrane, and cellwall continuum; signaling molecules in plant growth and development I and II. A list of participants is included.

  15. The gravity persistent signal (gps) Mutants of Arabidopsis: Insights into Gravitropic Signal Transduction

    NASA Astrophysics Data System (ADS)

    Wyatt, S.

    The gravitropic response of Arabidopsis stems is rapid with a visible within 30 min and vertical reorientation within 2 h. However, horizontal gravistimulation for 3 h at 4°C does not cause curvature. When the stems are subsequently placed in the vertical position at RT, they bend in response to the previous, horizontal gravistimulation. These results indicate that the gravity perception step can occur at 4°C, but that part of the response is sensitive to cold. At 4°C, starch-containing amyloplasts in the endodermis of the inflorescence stems sedimented normally but auxin transport was abolished indicating that the cold treatment affected early events of the signal transduction pathway that occur after amyloplast sedimentation but prior to auxin transport. The gps mutants of Arabidopsis are a unique group of mutants that respond abnormally after gravistimulation at 4°C. gps1 shows no response to the cold gravistimulation, gps2 bends the wrong way as compared to wild type and gps3 over responds, bending past the anticipated curvature. The mutants were selected from a T-DNA tagged population. Cloning strategies based on the tag have been employed to identify the genes disrupted. GPS1 was cloned using TAIL PCR and is At3g20130, a cytochrome P450, CYP705A22, of unknown function. GPS1p::GFP fusions are being used to determine temporal and spatial expression of GPS1. The mutation in gps3 appears to disrupt a non-coding region downstream of At1g43950 No function has yet been determined for this region, but it appears that the mutation disrupts transcription of a transcription factor homologous to the DNA binding domain of an auxin response factor (ARF) 9-like protein. The identity of GPS2 is as yet unknown. The gps mutants represent potentially three independent aspects of signal transduction in the gravitropic response: perception or retention of the gravity signal (gps1), determination of the polarity of the response (gps2), and the tissue specificity of the

  16. Endocytosis of pro-inflammatory cytokine receptors and its relevance for signal transduction.

    PubMed

    Hermanns, Heike M; Wohlfahrt, Julia; Mais, Christine; Hergovits, Sabine; Jahn, Daniel; Geier, Andreas

    2016-08-01

    The pro-inflammatory cytokines tumor necrosis factor (TNF), interleukin-1 (IL-1) and interleukin-6 (IL-6) are key players of the innate and adaptive immunity. Their activity needs to be tightly controlled to allow the initiation of an appropriate immune response as defense mechanism against pathogens or tissue injury. Excessive or sustained signaling of either of these cytokines leads to severe diseases, including rheumatoid arthritis, inflammatory bowel diseases (Crohn's disease, ulcerative colitis), steatohepatitis, periodic fevers and even cancer. Studies carried out in the last 30 years have emphasized that an elaborate control system for each of these cytokines exists. Here, we summarize what is currently known about the involvement of receptor endocytosis in the regulation of these pro-inflammatory cytokines' signaling cascades. Particularly in the last few years it was shown that this cellular process is far more than a mere feedback mechanism to clear cytokines from the circulation and to shut off their signal transduction.

  17. Signal Transduction: From the Atomic Age to the Post-Genomic Era

    PubMed Central

    Thorner, Jeremy; Hunter, Tony; Cantley, Lewis C.; Sever, Richard

    2016-01-01

    SUMMARY We have come a long way in the 55 years since Edmond Fischer and the late Edwin Krebs discovered that the activity of glycogen phosphorylase is regulated by reversible protein phosphorylation. Many of the fundamental molecular mechanisms that operate in biological signaling have since been characterized and the vast web of interconnected pathways that make up the cellular signaling network has been mapped in considerable detail. Nonetheless, it is important to consider how fast this field is still moving and the issues at the current boundaries of our understanding. One must also appreciate what experimental strategies have allowed us to attain our present level of knowledge. We summarize here some key issues (both conceptual and methodological), raise unresolved questions, discuss potential pitfalls, and highlight areas in which our understanding is still rudimentary. We hope these wide-ranging ruminations will be useful to investigators who carry studies of signal transduction forward during the rest of the 21st century. PMID:25359498

  18. Signal transduction: From the atomic age to the post-genomic era.

    PubMed

    Thorner, Jeremy; Hunter, Tony; Cantley, Lewis C; Sever, Richard

    2014-12-01

    We have come a long way in the 55 years since Edmond Fischer and the late Edwin Krebs discovered that the activity of glycogen phosphorylase is regulated by reversible protein phosphorylation. Many of the fundamental molecular mechanisms that operate in biological signaling have since been characterized and the vast web of interconnected pathways that make up the cellular signaling network has been mapped in considerable detail. Nonetheless, it is important to consider how fast this field is still moving and the issues at the current boundaries of our understanding. One must also appreciate what experimental strategies have allowed us to attain our present level of knowledge. We summarize here some key issues (both conceptual and methodological), raise unresolved questions, discuss potential pitfalls, and highlight areas in which our understanding is still rudimentary. We hope these wide-ranging ruminations will be useful to investigators who carry studies of signal transduction forward during the rest of the 21st century.

  19. Transduction of wound and herbivory signals in plastids

    PubMed Central

    Baldwin, Ian T

    2010-01-01

    Plastids are the central orchestrators of the early and late responses to wounding and herbivory in plants. This organelle houses some of the most important enzymes involved in the biogenesis of intra and extracellular signals that mediate defense responses against these stresses. Among these enzymes are the ones initiating the biosynthesis of oxylipins [e.g., jasmonic acid (JA) and C6 volatiles], terpenoid volatiles and phenolic compounds, including both volatile [e.g., methylsalicylate (MeSA)] and non-volatile compounds [e.g., salicylic acid (SA)]. Plastids also play a major role in orchestrating changes in primary metabolism during herbivory and thereby in the reallocation of carbon and nitrogen to different functions in response to herbivory. How the primary stress signals generated by mechanical damage and herbivory reach the plastid to activate the rapid synthesis of these signal molecules is at present largely unknown. PMID:20798815

  20. Restoration of autophagy alleviates hepatic ER stress and impaired insulin signalling transduction in high fructose-fed male mice.

    PubMed

    Wang, Hao; Sun, Ruo-Qiong; Zeng, Xiao-Yi; Zhou, Xiu; Li, Songpei; Jo, Eunjung; Molero, Juan C; Ye, Ji-Ming

    2015-01-01

    High-carbohydrate (mainly fructose) consumption is a major dietary factor for hepatic insulin resistance, involving endoplasmic reticulum (ER) stress and lipid accumulation. Because autophagy has been implicated in ER stress, the present study investigated the role of autophagy in high-fructose (HFru) diet-induced hepatic ER stress and insulin resistance in male C57BL/6J mice. The results show that chronic HFru feeding induced glucose intolerance and impaired insulin signaling transduction in the liver, associated with ER stress and the accumulation of lipids. Intriguingly, hepatic autophagy was suppressed as a result of activation of mammalian target of rapamycin. The suppressed autophagy was detected within 6 hours after HFru feeding along with activation of both inositol-requiring enzyme 1 and protein kinase RNA-like endoplasmic reticulum kinase pathways. These events occurred prior to lipid accumulation or lipogenesis and were sufficient to blunt insulin signaling transduction with activation of c-Jun N-terminal kinase/inhibitory-κB kinase and serine phosphorylation of insulin receptor substrate 1. The stimulation of autophagy attenuated ER stress- and c-Jun N-terminal kinase/inhibitory-κB kinase-associated impairment in insulin signaling transduction in a mammalian target of rapamycin -independent manner. Taken together, our data suggest that restoration of autophagy functions disrupted by fructose is able to alleviate ER stress and improve insulin signaling transduction.

  1. Molecular imaging of temporal dynamics and spatial heterogeneity of hypoxia-inducible factor-1 signal transduction activity in tumors in living mice.

    PubMed

    Serganova, Inna; Doubrovin, Michael; Vider, Jelena; Ponomarev, Vladimir; Soghomonyan, Suren; Beresten, Tatiana; Ageyeva, Ludmila; Serganov, Alexander; Cai, Shangde; Balatoni, Julius; Blasberg, Ronald; Gelovani, Juri

    2004-09-01

    Tumor hypoxia is a spatially and temporally heterogeneous phenomenon, which results from several tumor and host tissue-specific processes. To study the dynamics and spatial heterogeneity of hypoxia-inducible factor-1 (HIF-1)-specific transcriptional activity in tumors, we used repetitive noninvasive positron emission tomography (PET) imaging of hypoxia-induced HIF-1 transcriptional activity in tumors in living mice. This approach uses a novel retroviral vector bearing a HIF-1-inducible "sensor" reporter gene (HSV1-tk/GFP fusion) and a constitutively expressed "beacon" reporter gene (DsRed2/XPRT). C6 glioma cells transduced with this multireporter system revealed dose-dependent patterns in temporal dynamics of HIF-1 transcriptional activity induced by either CoCl2 or decreased atmospheric oxygen concentration. Multicellular spheroids of C6 reporter cells developed a hypoxic core when >350 microm in diameter. 18F-2'-fluoro-2'deoxy-1beta-D-arabionofuranosyl-5-ethyl-uracil (FEAU) PET revealed spatial heterogeneity of HIF-1 transcriptional activity in reporter xenografts in mice as a function of size or ischemia-reperfusion injury. With increasing tumor diameter (>3 mm), a marked increase in HIF-1 transcriptional activity was observed in the core regions of tumors. Even a moderate ischemia-reperfusion injury in small C6 tumors caused a rapid induction of HIF-1 transcriptional activity, which persisted for a long time because of the inability of C6 tumors to rapidly compensate acute changes in tumor microcirculation.

  2. Mitogen-activated protein kinase signal transduction and DNA repair network are involved in aluminum-induced DNA damage and adaptive response in root cells of Allium cepa L.

    PubMed Central

    Panda, Brahma B.; Achary, V. Mohan M.

    2014-01-01

    In the current study, we studied the role of signal transduction in aluminum (Al3+)-induced DNA damage and adaptive response in root cells of Allium cepa L. The root cells in planta were treated with Al3+ (800 μM) for 3 h without or with 2 h pre-treatment of inhibitors of mitogen-activated protein kinase (MAPK), and protein phosphatase. Also, root cells in planta were conditioned with Al3+ (10 μM) for 2 h and then subjected to genotoxic challenge of ethyl methane sulfonate (EMS; 5 mM) for 3 h without or with the pre-treatment of the aforementioned inhibitors as well as the inhibitors of translation, transcription, DNA replication and repair. At the end of treatments, roots cells were assayed for cell death and/or DNA damage. The results revealed that Al3+ (800 μM)-induced significant DNA damage and cell death. On the other hand, conditioning with low dose of Al3+ induced adaptive response conferring protection of root cells from genotoxic stress caused by EMS-challenge. Pre-treatment of roots cells with the chosen inhibitors prior to Al3+-conditioning prevented or reduced the adaptive response to EMS genotoxicity. The results of this study suggested the involvement of MAPK and DNA repair network underlying Al-induced DNA damage and adaptive response to genotoxic stress in root cells of A. cepa. PMID:24926302

  3. Organophosphorous pesticide metabolite (DEDTP) induces changes in the activation status of human lymphocytes by modulating the interleukin 2 receptor signal transduction pathway

    SciTech Connect

    Esquivel-Senties, M.S.; Barrera, I.; Ortega, A.; Vega, L.

    2010-10-15

    Diethyldithiophosphate (DEDTP) is a metabolite formed by biotransformation of organophosphorous (OP) compounds that has a longer half-life than its parental compound. Here we evaluate the effects of DEDTP on human CD4+ T lymphocytes. In vitro exposure to DEDTP (1-50 {mu}M) decreased [{sup 3}H]thymidine incorporation in resting cells and increased CD25 surface expression without altering cell viability. DEDTP treatment inhibited anti-CD3/anti-CD28 stimulation-induced CD4+ and CD8+ T cell proliferation determined by CFSE dilution. Decreased CD25 expression and intracellular IL-2 levels were correlated with this defect in cell proliferation. IL-2, IFN-{gamma} and IL-10 secretion were also reduced while IL-4 secretion was not altered. Increased phosphorylation of SOCS3 and dephosphorylation of STAT5 were induced by DEDTP after as little as 5 min of exposure. In addition, DEDTP induced phosphorylation of ERK, JNK and p38 and NFAT nuclear translocation. These results suggest that DEDTP can modulate phosphorylation of intracellular proteins such as SOCS3, which functions as a negative regulator of cytokine signalling, and that DEDTP exposure may thus cause T cells to fail to respond to further antigen challenges.

  4. Arsenic interferes with the signaling transduction pathway of T cell receptor activation by increasing basal and induced phosphorylation of Lck and Fyn in spleen cells

    SciTech Connect

    Soto-Pena, Gerson A.; Vega, Libia

    2008-07-15

    Arsenic is known to produce inhibition as well as induction of immune cells proliferative responses depending on the doses as one of its mechanisms of immunotoxicity. Here we evaluate the effect of arsenic exposure on the activation of splenic mononuclear cells (SMC) in male CD57BL6N mice. Intra-gastric exposure to arsenic (as sodium arsenite) for 30 days (1, 0.1, or 0.01 mg/kg/day), reduced the proportion of CD4+ cells and the CD4+/CD8+ ratio in the spleen, increasing the proportion of CD11b+ cells. Arsenic exposure did not modify the proportion of B cells. SMC showed an increased level of phosphorylation of lck and fyn kinases (first kinases associated to TCR complex when activated). Although normal levels of apoptosis were observed on freshly isolated SMC, an increase in apoptotic cells related with the increase in phosphorylation of lck and fyn was observed when SMC were activated with Concanavalin-A (Con-A). Arsenic exposure reduced the proliferative response of SMC to Con-A, and also reduced secretion of IL-2, IL-6, IL-12 and IFN{gamma}. No effect was observed on IL-4, and IL-10 secretion. The same effects were observed when SMC of exposed animals were activated with anti-CD3/CD28 antibodies for 24 h, but these effects were transitory since a recovery, up to control levels or even higher, were observed after 72 h of stimulation. This study demonstrates that repeated and prolonged exposure to arsenic alters cell populations and produces functional changes depending on the specific activation pathway, and could be related with the phosphorylation status of lck and fyn kinases.

  5. Nonreceptor protein tyrosine kinase involvement in signal transduction and immunodeficiency disease.

    PubMed

    Saouaf, S J; Burkhardt, A L; Bolen, J B

    1995-09-01

    The nonreceptor protein tyrosine kinases (PTKs) have been grouped into 10 different enzyme families based on predicted amino acid sequences. As the number of enzymes belonging to the nonreceptor class of PTK is increasing, one challenge is to determine how these various classes of PTKs interact within the cell to promote signal transduction. Herein, the activation of four classes of nonreceptor PTKs is discussed in relation to their interactions with each other as well as with other signaling molecules during the process of lymphocyte surface antigen receptor-mediated activation. Recent findings of nonreceptor PTK loss-of-function mutations in different immunodeficiency diseases has revealed the important contribution of this group of enzymes to lymphocyte development. PMID:7554458

  6. MAPKs and Signal Transduction in the Control of Gastrointestinal Epithelial Cell Proliferation and Differentiation

    PubMed Central

    Osaki, Luciana H.; Gama, Patrícia

    2013-01-01

    Mitogen-activated protein kinase (MAPK) pathways are activated by several stimuli and transduce the signal inside cells, generating diverse responses including cell proliferation, differentiation, migration and apoptosis. Each MAPK cascade comprises a series of molecules, and regulation takes place at different levels. They communicate with each other and with additional pathways, creating a signaling network that is important for cell fate determination. In this review, we focus on ERK, JNK, p38 and ERK5, the major MAPKs, and their interactions with PI3K-Akt, TGFβ/Smad and Wnt/β-catenin pathways. More importantly, we describe how MAPKs regulate cell proliferation and differentiation in the rapidly renewing epithelia that lines the gastrointestinal tract and, finally, we highlight the recent findings on nutritional aspects that affect MAPK transduction cascades. PMID:23670595

  7. Roles of Intracellular Cyclic AMP Signal Transduction in the Capacitation and Subsequent Hyperactivation of Mouse and Boar Spermatozoa

    PubMed Central

    HARAYAMA, Hiroshi

    2013-01-01

    It is not until accomplishment of a variety of molecular changes during the transit through the female reproductive tract that mammalian spermatozoa are capable of exhibiting highly activated motility with asymmetric whiplash beating of the flagella (hyperactivation) and undergoing acrosomal exocytosis in the head (acrosome reaction). These molecular changes of the spermatozoa are collectively termed capacitation and promoted by bicarbonate, calcium and cholesterol acceptors. Such capacitation-promoting factors can stimulate intracellular cyclic AMP (cAMP) signal transduction in the spermatozoa. Meanwhile, hyperactivation and the acrosome reaction are essential to sperm fertilization with oocytes and are apparently triggered by a sufficient increase of intracellular Ca2+ in the sperm flagellum and head, respectively. Thus, it is necessary to investigate the relationship between cAMP signal transduction and calcium signaling cascades in the spermatozoa for the purpose of understanding the molecular basis of capacitation. In this review, I cover updated insights regarding intracellular cAMP signal transduction, the acrosome reaction and flagellar motility in mammalian spermatozoa and then account for possible roles of intracellular cAMP signal transduction in the capacitation and subsequent hyperactivation of mouse and boar spermatozoa. PMID:24162806

  8. Analysis of a heme-dependent signal transduction system in Corynebacterium diphtheriae: deletion of the chrAS genes results in heme sensitivity and diminished heme-dependent activation of the hmuO promoter.

    PubMed

    Bibb, Lori A; King, Natalie D; Kunkle, Carey A; Schmitt, Michael P

    2005-11-01

    The Corynebacterium diphtheriae hmuO gene encodes a heme oxygenase that is involved in the utilization of heme as an iron source. Transcription of hmuO is activated by heme or hemoglobin and repressed by iron and DtxR. Previous studies with Escherichia coli showed that heme-dependent transcriptional activation of an hmuO promoter-lacZ fusion was dependent on the cloned C. diphtheriae chrA and chrS genes (chrAS), which encode the response regulator and sensor kinase, respectively, of a two-component signal transduction system. In this study, nonpolar deletions in the chrAS genes were constructed on the chromosome of C. diphtheriae. Mutations in chrAS resulted in marked reduction in heme-dependent transcription of hmuO, which indicates that the ChrA/S system is a key regulator at the hmuO promoter. However, low but significant levels of heme-specific transcriptional activity were observed at the hmuO promoter in the chrAS mutants, suggesting that an additional heme-dependent activator is involved in hmuO expression. The chrAS mutants were also sensitive to heme, which was observed only in stationary-phase cultures and correlated with reduced cell viability. The heme sensitivity of the mutants was not due to reduced expression of hmuO, and these results suggest that additional factors controlled by the ChrA/S system may be involved in protection against heme toxicity. Transcriptional analysis of the chrAS operon revealed that it was not autoregulated or affected by iron or heme levels.

  9. Nanosecond pulsed electric fields modulate cell function through intracellular signal transduction mechanisms.

    PubMed

    Beebe, Stephen J; Blackmore, Peter F; White, Jody; Joshi, Ravindra P; Schoenbach, Karl H

    2004-08-01

    These studies describe the effects of nanosecond (10-300 ns) pulsed electric fields (nsPEF) on mammalian cell structure and function. As the pulse durations decrease, effects on the plasma membrane (PM) decrease and effects on intracellular signal transduction mechanisms increase. When nsPEF-induced PM electroporation effects occur, they are distinct from classical PM electroporation effects, suggesting unique, nsPEF-induced PM modulations. In HL-60 cells, nsPEF that are well below the threshold for PM electroporation and apoptosis induction induce effects that are similar to purinergic agonistmediated calcium release from intracellular stores, which secondarily initiate capacitive calcium influx through store-operated calcium channels in the PM. NsPEF with durations and electric field intensities that do or do not cause PM electroporation, induce apoptosis in mammalian cells with a well-characterized phenotype typified by externalization of phosphatidylserine on the outer PM and activation of caspase proteases. Treatment of mouse fibrosarcoma tumors with nsPEF also results in apoptosis induction. When Jurkat cells were transfected by electroporation and then treated with nsPEF, green fluorescent protein expression was enhanced compared to electroporation alone. The results indicate that nsPEF activate intracellular mechanisms that can determine cell function and fate, providing an important new tool for probing signal transduction mechanisms that modulate cell structure and function and for potential therapeutic applications for cancer and gene therapy.

  10. Citrobacter rodentium espB Is Necessary for Signal Transduction and for Infection of Laboratory Mice

    PubMed Central

    Newman, Joseph V.; Zabel, Brian A.; Jha, Sharda S.; Schauer, David B.

    1999-01-01

    Citrobacter rodentium is the causative agent of transmissible murine colonic hyperplasia and contains a locus of enterocyte effacement (LEE) similar to that found in enteropathogenic Escherichia coli (EPEC). EPEC espB is necessary for intimate attachment and signal transduction between EPEC and cultured cell monolayers. Mice challenged with wild-type C. rodentium develop a mucosal immunoglobulin A response to EspB. In this study, C. rodentium espB has been cloned and its nucleotide sequence has been determined. C. rodentium espB was found to have 90% identity to EPEC espB. A nonpolar insertion mutation in C. rodentium espB was constructed and used to replace the chromosomal wild-type allele. The C. rodentium espB mutant exhibited reduced cell association and had no detectable fluorescent actin staining activity on cultured cell monolayers. The C. rodentium espB mutant also failed to colonize laboratory mice following experimental inoculation. The espB mutation could be complemented with a plasmid-encoded copy of the gene, which restored both cell association and fluorescent actin staining activity, as well as the ability to colonize laboratory mice. These studies indicate that espB is necessary for signal transduction and for colonization of laboratory mice by C. rodentium. PMID:10531262

  11. New paradigms in chemokine receptor signal transduction: Moving beyond the two-site model.

    PubMed

    Kleist, Andrew B; Getschman, Anthony E; Ziarek, Joshua J; Nevins, Amanda M; Gauthier, Pierre-Arnaud; Chevigné, Andy; Szpakowska, Martyna; Volkman, Brian F

    2016-08-15

    Chemokine receptor (CKR) signaling forms the basis of essential immune cellular functions, and dysregulated CKR signaling underpins numerous disease processes of the immune system and beyond. CKRs, which belong to the seven transmembrane domain receptor (7TMR) superfamily, initiate signaling upon binding of endogenous, secreted chemokine ligands. Chemokine-CKR interactions are traditionally described by a two-step/two-site mechanism, in which the CKR N-terminus recognizes the chemokine globular core (i.e. site 1 interaction), followed by activation when the unstructured chemokine N-terminus is inserted into the receptor TM bundle (i.e. site 2 interaction). Several recent studies challenge the structural independence of sites 1 and 2 by demonstrating physical and allosteric links between these supposedly separate sites. Others contest the functional independence of these sites, identifying nuanced roles for site 1 and other interactions in CKR activation. These developments emerge within a rapidly changing landscape in which CKR signaling is influenced by receptor PTMs, chemokine and CKR dimerization, and endogenous non-chemokine ligands. Simultaneous advances in the structural and functional characterization of 7TMR biased signaling have altered how we understand promiscuous chemokine-CKR interactions. In this review, we explore new paradigms in CKR signal transduction by considering studies that depict a more intricate architecture governing the consequences of chemokine-CKR interactions. PMID:27106080

  12. New paradigms in chemokine receptor signal transduction: Moving beyond the two-site model.

    PubMed

    Kleist, Andrew B; Getschman, Anthony E; Ziarek, Joshua J; Nevins, Amanda M; Gauthier, Pierre-Arnaud; Chevigné, Andy; Szpakowska, Martyna; Volkman, Brian F

    2016-08-15

    Chemokine receptor (CKR) signaling forms the basis of essential immune cellular functions, and dysregulated CKR signaling underpins numerous disease processes of the immune system and beyond. CKRs, which belong to the seven transmembrane domain receptor (7TMR) superfamily, initiate signaling upon binding of endogenous, secreted chemokine ligands. Chemokine-CKR interactions are traditionally described by a two-step/two-site mechanism, in which the CKR N-terminus recognizes the chemokine globular core (i.e. site 1 interaction), followed by activation when the unstructured chemokine N-terminus is inserted into the receptor TM bundle (i.e. site 2 interaction). Several recent studies challenge the structural independence of sites 1 and 2 by demonstrating physical and allosteric links between these supposedly separate sites. Others contest the functional independence of these sites, identifying nuanced roles for site 1 and other interactions in CKR activation. These developments emerge within a rapidly changing landscape in which CKR signaling is influenced by receptor PTMs, chemokine and CKR dimerization, and endogenous non-chemokine ligands. Simultaneous advances in the structural and functional characterization of 7TMR biased signaling have altered how we understand promiscuous chemokine-CKR interactions. In this review, we explore new paradigms in CKR signal transduction by considering studies that depict a more intricate architecture governing the consequences of chemokine-CKR interactions.

  13. An intimate link: two-component signal transduction systems and metal transport systems in bacteria

    PubMed Central

    Singh, Kamna; Senadheera, Dilani B; Cvitkovitch, Dennis G

    2014-01-01

    Bacteria have evolved various strategies to contend with high concentrations of environmental heavy metal ions for rapid, adaptive responses to maintain cell viability. Evidence gathered in the past two decades suggests that bacterial two-component signal transduction systems (TCSTSs) are intimately involved in monitoring cation accumulation, and can regulate the expression of related metabolic and virulence genes to elicit adaptive responses to changes in the concentration of these ions. Using examples garnered from recent studies, we summarize the cross-regulatory relationships between metal ions and TCSTSs. We present evidence of how bacterial TCSTSs modulate metal ion homeostasis and also how metal ions, in turn, function to control the activities of these signaling systems linked with bacterial survival and virulence. PMID:25437189

  14. A CRISPR-Based Toolbox for Studying T Cell Signal Transduction

    PubMed Central

    Chi, Shen; Weiss, Arthur; Wang, Haopeng

    2016-01-01

    CRISPR/Cas9 system is a powerful technology to perform genome editing in a variety of cell types. To facilitate the application of Cas9 in mapping T cell signaling pathways, we generated a toolbox for large-scale genetic screens in human Jurkat T cells. The toolbox has three different Jurkat cell lines expressing distinct Cas9 variants, including wild-type Cas9, dCas9-KRAB, and sunCas9. We demonstrated that the toolbox allows us to rapidly disrupt endogenous gene expression at the DNA level and to efficiently repress or activate gene expression at the transcriptional level. The toolbox, in combination with multiple currently existing genome-wide sgRNA libraries, will be useful to systematically investigate T cell signal transduction using both loss-of-function and gain-of-function genetic screens. PMID:27057542

  15. Mutations at the SPINDLY locus of Arabidopsis alter gibberellin signal transduction.

    PubMed

    Jacobsen, S E; Olszewski, N E

    1993-08-01

    Three independent recessive mutations at the SPINDLY (SPY) locus of Arabidopsis confer resistance to the gibberellin (GA) biosynthesis inhibitor paclobutrazol. Relative to wild type, spy mutants exhibit longer hypocotyls, leaves that are a lighter green color, increased stem elongation, early flowering, parthenocarpy, and partial male sterility. All of these phenotypes are also observed when wild-type Arabidopsis plants are repeatedly treated with gibberellin A3 (GA3). The spy-1 allele is partially epistatic to the ga1-2 mutation, which causes GA deficiency. In addition, the spy-1 mutation can simultaneously suppress the effects of the ga1-2 mutation and paclobutrazol treatment, which inhibit different steps in the GA biosynthesis pathway. This observation suggests that spy-1 activates a basal level of GA signal transduction that is independent of GA. Furthermore, results from GA3 dose-response experiments suggest that GA3 and spy-1 interact in an additive manner. These results are consistent with models in which the SPY gene product regulates a portion of the GA signal transduction pathway. PMID:8400871

  16. Dynamic localization of a cytoplasmic signal transduction response regulator controls morphogenesis during the Caulobacter cell cycle

    PubMed Central

    Jacobs, Christine; Hung, Dean; Shapiro, Lucy

    2001-01-01

    We present evidence that a bacterial signal transduction cascade that couples morphogenesis with cell cycle progression is regulated by dynamic localization of its components. Previous studies have implicated two histidine kinases, DivJ and PleC, and the response regulator, DivK, in the regulation of morphogenesis in the dimorphic bacterium Caulobacter crescentus. Here, we show that the cytoplasmic response regulator, DivK, exhibits a dynamic, cyclical localization that culminates in asymmetric distribution of DivK within the two cell types that are characteristic of the Caulobacter cell cycle; DivK is dispersed throughout the cytoplasm of the progeny swarmer cell and is localized to the pole of the stalked cell. The membrane-bound DivJ and PleC histidine kinases, which are asymmetrically localized at the opposite poles of the predivisional cell, control the temporal and spatial localization of DivK. DivJ mediates DivK targeting to the poles whereas PleC controls its release from one of the poles at times and places that are consistent with the activities and location of DivJ and PleC in the late predivisional cell. Thus, dynamic changes in subcellular location of multiple components of a signal transduction cascade may constitute a novel mode of prokaryotic regulation to generate and maintain cellular asymmetry. PMID:11274434

  17. Sexual Dimorphism and Developmental Expression of Signal-Transduction Machinery in the Vomeronasal Organ

    PubMed Central

    Murphy, F.A.; Tucker, K.; Fadool, D.A.

    2011-01-01

    We have explored the use of a new model to study the transduction of chemosignals in the vomeronasal organ (VNO), for which the functional pathway for chemical communication is incompletely understood. Because putative vomeronasal receptors in mammalian and other vertebrate models belong to the superfamily of G-protein-coupled receptors, the objective of the present study was to define which G-protein subunits were present in the VNO of Sternotherus odoratus (stinkpot or musk turtle) in order to provide directionality for future functional studies of the downstream signaling cascades. The turtle vomeronasal epithelium (VNE) was found to contain the G-proteins Gβ and Gαi1–3 at the microvillar layer, the presumed site of signal tranduction in these neurons, as evidenced by immunocytochemical techniques. Gαo labeled the axon bundles in the VNE and the somata of the vomeronasal sensory neurons but not the microvillar layer. Densitometric analysis of Western blots indicated that the VNO from females contained greater concentrations of Gαi1–3 compared with males. Sexually immature (juvenile) turtles showed intense immunolabeling for all three subunits (Gβ, Gαi1–3, and Gαo) in the axon bundles and an absence of labeling in the microvillar layer. Another putative signaling component found in the microvilli of mammalian VNO, transient receptor potential channel, was also immunoreactive in S. odoratus in a gender-specific manner, as quantified by Western blot analysis. These data demonstrate the utility of Sternotherus for discerning the functional signal transduction machinery in the VNO and may suggest that gender and developmental differences in effector proteins or cellular signaling components may be used to activate sex-specific behaviors. PMID:11241377

  18. Signal transduction by M3 muscarinic acetylcholine receptor in prostate cancer

    PubMed Central

    GUO, LIQIANG; LIU, YUQIANG; DING, ZHIBO; SUN, WENDONG; YUAN, MINGZHEN

    2016-01-01

    The present study aimed to investigate the potential mechanisms used during signal transduction by M3 muscarinic acetylcholine receptor (CHRM3) in prostate cancer. The microarray datasets of GSE3325, including 5 clinically localized primary prostate cancers and 4 benign prostate tissues, were downloaded from the Gene Expression Omnibus database. The differentially-expressed genes (DEGs) in primary prostate cancer tissues compared with benign controls were screened using the Limma package. Gene Ontology and pathway enrichment analyses were performed using the Database for Annotation Visualization and Integrated Discovery. Next, a protein-protein interaction (PPI) network was constructed. Additionally, microRNAs (miRNAs) associated with DEGs were predicted and miRNA-target DEG analysis was performed using a Web-based Gene Set Analysis Toolkit. Finally, the PPI network and the miRNA-target DEG network were integrated using Cytoscape. In total, 224 DEGs were screened in the prostate cancer tissues, including 113 upregulated and 111 downregulated genes. CHRM3 and epidermal growth factor (EGF) were enriched in the regulation of the actin cytoskeleton. EGF and v-myc avian myelocytomatosis viral oncogene homolog (Myc) were enriched in the mitogen-activated protein kinase (MAPK) signaling pathway. EGF with the highest degree of connectivity was the hub node in the PPI network, and miR-34b could interact with Myc directly in the miRNA-target DEG network. EGF and Myc may exhibit significant roles in the progression of prostate cancer via regulation of the actin cytoskeleton and the MAPK signaling pathway. CHRM3 may activate these two pathways in prostate cancer progression. Thus, these two key factors and pathways may be crucial mechanisms during signal transduction by CHRM3 in prostate cancer. PMID:26870222

  19. 2R and remodeling of vertebrate signal transduction engine

    PubMed Central

    2010-01-01

    Background Whole genome duplication (WGD) is a special case of gene duplication, observed rarely in animals, whereby all genes duplicate simultaneously through polyploidisation. Two rounds of WGD (2R-WGD) occurred at the base of vertebrates, giving rise to an enormous wave of genetic novelty, but a systematic analysis of functional consequences of this event has not yet been performed. Results We show that 2R-WGD affected an overwhelming majority (74%) of signalling genes, in particular developmental pathways involving receptor tyrosine kinases, Wnt and transforming growth factor-β ligands, G protein-coupled receptors and the apoptosis pathway. 2R-retained genes, in contrast to tandem duplicates, were enriched in protein interaction domains and multifunctional signalling modules of Ras and mitogen-activated protein kinase cascades. 2R-WGD had a fundamental impact on the cell-cycle machinery, redefined molecular building blocks of the neuronal synapse, and was formative for vertebrate brains. We investigated 2R-associated nodes in the context of the human signalling network, as well as in an inferred ancestral pre-2R (AP2R) network, and found that hubs (particularly involving negative regulation) were preferentially retained, with high connectivity driving retention. Finally, microarrays and proteomics demonstrated a trend for gradual paralog expression divergence independent of the duplication mechanism, but inferred ancestral expression states suggested preferential subfunctionalisation among 2R-ohnologs (2ROs). Conclusions The 2R event left an indelible imprint on vertebrate signalling and the cell cycle. We show that 2R-WGD preferentially retained genes are associated with higher organismal complexity (for example, locomotion, nervous system, morphogenesis), while genes associated with basic cellular functions (for example, translation, replication, splicing, recombination; with the notable exception of cell cycle) tended to be excluded. 2R-WGD set the stage

  20. Molecular Insights into Toluene Sensing in the TodS/TodT Signal Transduction System.

    PubMed

    Koh, Serry; Hwang, Jungwon; Guchhait, Koushik; Lee, Eun-Gyeong; Kim, Sang-Yoon; Kim, Sujin; Lee, Sangmin; Chung, Jeong Min; Jung, Hyun Suk; Lee, Sang Jun; Ryu, Choong-Min; Lee, Seung-Goo; Oh, Tae-Kwang; Kwon, Ohsuk; Kim, Myung Hee

    2016-04-15

    TodS is a sensor kinase that responds to various monoaromatic compounds, which either cause an agonistic or antagonistic effect on phosphorylation of its cognate response regulator TodT, and controls tod operon expression in Pseudomonas putida strains. We describe a molecular sensing mechanism of TodS that is activated in response to toluene. The crystal structures of the TodS Per-Arnt-Sim (PAS) 1 sensor domain (residues 43-164) and its complex with toluene (agonist) or 1,2,4-trimethylbenzene (antagonist) show a typical β2α3β3 PAS fold structure (residues 45-149), forming a hydrophobic ligand-binding site. A signal transfer region (residues 150-163) located immediately after the canonical PAS fold may be intrinsically flexible and disordered in both apo-PAS1 and antagonist-bound forms and dramatically adapt an α-helix upon toluene binding. This structural change in the signal transfer region is proposed to result in signal transmission to activate the TodS/TodT two-component signal transduction system. Site-directed mutagenesis and β-galactosidase assays using a P. putida reporter strain system verified the essential residues involved in ligand sensing and signal transfer and suggest that the Phe(46) residue acts as a ligand-specific switch.

  1. Molecular Insights into Toluene Sensing in the TodS/TodT Signal Transduction System*

    PubMed Central

    Koh, Serry; Hwang, Jungwon; Guchhait, Koushik; Lee, Eun-Gyeong; Kim, Sang-Yoon; Kim, Sujin; Lee, Sangmin; Chung, Jeong Min; Jung, Hyun Suk; Lee, Sang Jun; Ryu, Choong-Min; Lee, Seung-Goo; Oh, Tae-Kwang; Kwon, Ohsuk; Kim, Myung Hee

    2016-01-01

    TodS is a sensor kinase that responds to various monoaromatic compounds, which either cause an agonistic or antagonistic effect on phosphorylation of its cognate response regulator TodT, and controls tod operon expression in Pseudomonas putida strains. We describe a molecular sensing mechanism of TodS that is activated in response to toluene. The crystal structures of the TodS Per-Arnt-Sim (PAS) 1 sensor domain (residues 43–164) and its complex with toluene (agonist) or 1,2,4-trimethylbenzene (antagonist) show a typical β2α3β3 PAS fold structure (residues 45–149), forming a hydrophobic ligand-binding site. A signal transfer region (residues 150–163) located immediately after the canonical PAS fold may be intrinsically flexible and disordered in both apo-PAS1 and antagonist-bound forms and dramatically adapt an α-helix upon toluene binding. This structural change in the signal transfer region is proposed to result in signal transmission to activate the TodS/TodT two-component signal transduction system. Site-directed mutagenesis and β-galactosidase assays using a P. putida reporter strain system verified the essential residues involved in ligand sensing and signal transfer and suggest that the Phe46 residue acts as a ligand-specific switch. PMID:26903514

  2. 14-3-3ζ up-regulates hypoxia-inducible factor-1α in hepatocellular carcinoma via activation of PI3K/Akt/NF-кB signal transduction pathway

    PubMed Central

    Tang, Yufu; Lv, Pengfei; Sun, Zhongyi; Han, Lei; Luo, Bichao; Zhou, Wenping

    2015-01-01

    14-3-3ζ protein, a member of 14-3-3 family, plays important roles in multiple cellular processes. Our previous study showed that 14-3-3ζ could bind to regulate the expression of hypoxia-inducible factor-1α (HIF-1α), which is induced by hypoxia and a crucial factor for induction of tumor metastasis. Moreover, we also have confirmed the response of 14-3-3ζ to hypoxia in our unpublished data as well. Thus, in the present study, we attempted to reveal that whether the regulation effect of 14-3-3ζ on HIF-1α functioned in a similar pattern as hypoxia. Stable regulation of 14-3-3ζ in human HCC cell line SMMC-772 and HCC-LM3 was achieved. The regulation of 14-3-3ζ on HIF-1α mRNA transcription was evaluated by luciferase activity assay and quantitative real-time PCR (qPCR). The effect of 14-3-3ζ on the production of HIF-1α and pathways determining HIF-1α’s response to hypoxia was assessed using western blotting assay. Our results showed that regulation of 14-3-3ζ expression influenced the activity of HIF-1α, phosphatidyl inositol 3-kinase (PI3K), Akt, extracellular signal-regulated kinase 1/2 (ERK1/2), and nuclear factor kappa B (NF-кB). Blocking of these pathways using indicated inhibitors revealed that 14-3-3ζ enhanced the production of HIF-1α via the activation of PI3K/Akt/NF-кB pathway, which was identical to hypoxia induced HIF-1α expression. For the first time, our study described the key role of 14-3-3ζ in the HIF-1α production in HCC cells. And the molecule exerted its function on HIF-1α both by directly binding to it and via PI3K/Akt/NF-кB signal transduction pathway. PMID:26884855

  3. Fc gamma R-dependent mitogen-activated protein kinase activation in leukocytes: a common signal transduction event necessary for expression of TNF-alpha and early activation genes

    PubMed Central

    1996-01-01

    Cross-linking the receptors for the Fc domain of IgG (Fc gamma R) on leukocytes induces activation of protein tyrosine kinases. The intermediary molecules that transduce to the nucleus the signals leading to induction of the diverse biological responses mediated by these receptors are not clearly identified. We have investigated whether mitogen-activated protein kinases (MAPK) are involved in transmembrane signaling via the three Fc gamma R present on monocytic, polymorphonuclear, and natural killer (NK) cells. Our results indicate that occupancy of Fc gamma RI and Fc gamma RII on the monocytic cell line THP-I and on polymorphonuclear leukocytes (PMN) induces, transiently and with fast kinetics, MAPK phosphorylation, as indicated by decreased electrophoretic mobility in sodium dodecyl sulfate- polyacrylamide gel electrophoresis, and increased amounts of the proteins in antiphosphotyrosine antibody immunoprecipitates. This, associated with increased enzymatic activity, also occurs upon stimulation of the transmembrane isoform of CD16 (Fc gamma RIIIA) in NK cells and in a T cell line expressing transfected Fc gamma RIIIA alpha ligand-binding chain in association with zeta, but not upon stimulation of the glycosil-phosphatidylinositol-anchored Fc gamma RIIIB on PMN. Using the specific MAP kinase kinase inhibitor-PD 098059, we show that activation of MAPK is necessary for the Fc gamma R-dependent induction of c-fos and tumor necrosis factor alpha mRNA expression in monocytes and NK cells. These results underscore the role of MAPK as signal- transducing molecules controlling the expression of different genes relevant to leukocyte biology upon Fc gamma R stimulation. PMID:9064320

  4. Nonselective block by La3+ of Arabidopsis ion channels involved in signal transduction

    NASA Technical Reports Server (NTRS)

    Lewis, B. D.; Spalding, E. P.; Evans, M. L. (Principal Investigator)

    1998-01-01

    Lanthanide ions such as La3+ are frequently used as blockers to test the involvement of calcium channels in plant and animal signal transduction pathways. For example, the large rise in cytoplasmic Ca2+ concentration triggered by cold shock in Arabidopsis seedlings is effectively blocked by 10 mM La3+ and we show here that the simultaneous large membrane depolarization is similarly blocked. However, a pharmacological tool is only as useful as it is selective and the specificity of La3+ for calcium channels was brought into question by our finding that it also blocked a blue light (BL)-induced depolarization that results from anion channel activation and believed not to involve calcium channels. This unexpected inhibitory effect of La3+ on the BL-induced depolarization is explained by our finding that 10 mM La3+ directly and completely blocked the BL-activated anion channel when applied to excised patches. We have investigated the ability of La3+ to block noncalcium channels in Arabidopsis. In addition to the BL-activated anion channel, 10 mM La3+ blocked a cation channel and a stretch-activated channel in patches of plasma membrane excised from hypocotyl cells. In root cells, 10 mM La3+ inhibited the activity of an outward-rectifying potassium channel at the whole cell and single-channel level by 47% and 58%, respectively. We conclude that La3+ is a nonspecific blocker of multiple ionic conductances in Arabidopsis and may disrupt signal transduction processes independently of any effect on Ca2+ channels.

  5. Analysis of nitrated proteins in Saccharomyces cerevisiae involved in mating signal transduction.

    PubMed

    Kang, Jeong Won; Lee, Na Young; Cho, Kyung-Cho; Lee, Min Young; Choi, Do-Young; Park, Sang-Hyun; Kim, Kwang Pyo

    2015-01-01

    Protein tyrosine nitration (PTN) is a PTM that regulates signal transduction and inflammatory responses, and is related to neurodegenerative and cardiovascular diseases. The cellular function of PTN remains unclear because the low stoichiometry of PTN limits the identification and quantification of nitrated peptides. Effective enrichment is an important aspect of PTN analysis. In this study, we analyzed the in vivo nitroproteome elicited by mating signal transduction in Saccharomyces cerevisiae using a novel chemical enrichment method followed by LC-MS/MS. Nitroproteome profiling successfully identified changes in the nitration states of 14 proteins during mating signal transduction in S. cerevisiae, making this the first reported in vivo nitroproteome in yeast. We investigated the biological functions of these nitroproteins and their relationships to mating signal transduction in S. cerevisiae using a protein-protein interaction network. Our results suggest that PTN and denitration may be involved in nonreactive nitrogen species-mediated signal transduction and can provide clues for understanding the functional roles of PTN in vivo.

  6. Novel optical methodologies in studying mechanical signal transduction in mammalian cells

    NASA Technical Reports Server (NTRS)

    Stamatas, G. N.; McIntire, L. V.

    1999-01-01

    For the last 3 decades evidence has been accumulating that some types of mammalian cells respond to their mechanically active environment by altering their morphology, growth rate, and metabolism. The study of such responses is very important in understanding, physiological and pathological conditions ranging from bone formation to atherosclerosis. Obtaining this knowledge has been the goal for an active research area in bioengineering termed cell mechanotransduction. The advancement of optical methodologies used in cell biology research has given the tools to elucidate cellular mechanisms that would otherwise be impossible to visualize. Combined with molecular biology techniques, they give engineers invaluable tools in understanding the chemical pathways involved in mechanotransduction. Herein we briefly review the current knowledge on mechanical signal transduction in mammalian cells, focusing on the application of novel optical techniques in the ongoing research.

  7. Phosphodiesterase 4D acts downstream of Neuropilin to control Hedgehog signal transduction and the growth of medulloblastoma.

    PubMed

    Ge, Xuecai; Milenkovic, Ljiljana; Suyama, Kaye; Hartl, Tom; Purzner, Teresa; Winans, Amy; Meyer, Tobias; Scott, Matthew P

    2015-01-01

    Alterations in Hedgehog (Hh) signaling lead to birth defects and cancers including medulloblastoma, the most common pediatric brain tumor. Although inhibitors targeting the membrane protein Smoothened suppress Hh signaling, acquired drug resistance and tumor relapse call for additional therapeutic targets. Here we show that phosphodiesterase 4D (PDE4D) acts downstream of Neuropilins to control Hh transduction and medulloblastoma growth. PDE4D interacts directly with Neuropilins, positive regulators of Hh pathway. The Neuropilin ligand Semaphorin3 enhances this interaction, promoting PDE4D translocation to the plasma membrane and cAMP degradation. The consequent inhibition of protein kinase A (PKA) enhances Hh transduction. In the developing cerebellum, genetic removal of Neuropilins reduces Hh signaling activity and suppresses proliferation of granule neuron precursors. In mouse medulloblastoma allografts, PDE4D inhibitors suppress Hh transduction and inhibit tumor growth. Our findings reveal a new regulatory mechanism of Hh transduction, and highlight PDE4D as a promising target to treat Hh-related tumors. PMID:26371509

  8. Phosphodiesterase 4D acts downstream of Neuropilin to control Hedgehog signal transduction and the growth of medulloblastoma

    PubMed Central

    Ge, Xuecai; Milenkovic, Ljiljana; Suyama, Kaye; Hartl, Tom; Purzner, Teresa; Winans, Amy; Meyer, Tobias; Scott, Matthew P

    2015-01-01

    Alterations in Hedgehog (Hh) signaling lead to birth defects and cancers including medulloblastoma, the most common pediatric brain tumor. Although inhibitors targeting the membrane protein Smoothened suppress Hh signaling, acquired drug resistance and tumor relapse call for additional therapeutic targets. Here we show that phosphodiesterase 4D (PDE4D) acts downstream of Neuropilins to control Hh transduction and medulloblastoma growth. PDE4D interacts directly with Neuropilins, positive regulators of Hh pathway. The Neuropilin ligand Semaphorin3 enhances this interaction, promoting PDE4D translocation to the plasma membrane and cAMP degradation. The consequent inhibition of protein kinase A (PKA) enhances Hh transduction. In the developing cerebellum, genetic removal of Neuropilins reduces Hh signaling activity and suppresses proliferation of granule neuron precursors. In mouse medulloblastoma allografts, PDE4D inhibitors suppress Hh transduction and inhibit tumor growth. Our findings reveal a new regulatory mechanism of Hh transduction, and highlight PDE4D as a promising target to treat Hh-related tumors. DOI: http://dx.doi.org/10.7554/eLife.07068.001 PMID:26371509

  9. XB130: A novel adaptor protein in cancer signal transduction

    PubMed Central

    ZHANG, RUIYAO; ZHANG, JINGYAO; WU, QIFEI; MENG, FANDI; LIU, CHANG

    2016-01-01

    Adaptor proteins are functional proteins that contain two or more protein-binding modules to link signaling proteins together, which affect cell growth and shape and have no enzymatic activity. The actin filament-associated protein (AFAP) family is an important member of the adaptor proteins, including AFAP1, AFAP1L1 and AFAP1L2/XB130. AFAP1 and AFAP1L1 share certain common characteristics and function as an actin-binding protein and a cSrc-activating protein. XB130 exhibits certain unique features in structure and function. The mRNA of XB130 is expressed in human spleen, thyroid, kidney, brain, lung, pancreas, liver, colon and stomach, and the most prominent disease associated with XB130 is cancer. XB130 has a controversial effect on cancer. Studies have shown that XB130 can promote cancer progression and downregulation of XB130-reduced growth of tumors derived from certain cell lines. A higher mRNA level of XB130 was shown to be associated with a better survival in non-small cell lung cancer. Previous studies have shown that XB130 can regulate cell growth, migration and invasion and possibly has the effect through the cAMP-cSrc-phosphoinositide 3-kinase/Akt pathway. Except for cancer, XB130 is also associated with other pathological or physiological procedures, such as airway repair and regeneration. PMID:26998266

  10. [Rho-mediated signal transduction and its physiological roles].

    PubMed

    Ishizaki, Toshimasa

    2003-03-01

    Rho is a member of the Ras-related family of small molecular weight GTP-binding proteins, and Rho works as a molecular switch by shuttling between the GDP-bound inactive form and the GTP-bound active form. Rho is involved in cell motility, cell adhesion, and cytokinesis through the reorganization of the actin cytoskeleton. In addition to this, Rho also regulates Ras-induced transformation, transcriptional activation and cell cycle progression. These actions through the Rho signaling are mediated by downstream Rho effectors. Several putative Rho effectors including ROCK and mDia have been isolated on the basis of their selective binding to the GTP-bound form of Rho. Among them, the ROCK family of Rho-associated serine/threonine protein kinases inactivates myosin phosphatase and actin depolymerizing factor (cofilin/Destrin) to induce stabilization of filamentous actin and increase in the actomyosin-based contractility. mDia binds profilin likely to promote actin polymerization. Thus, these effectors are supposed to work in organization of the actin cytoskeleton. Furthermore, analyses using a ROCK specific inhibitor Y-27632 have suggested that the Rho-ROCK pathway works in contractions of vascular smooth muscles and is involved in malignant cell transformation and tumor invasion and metastasis.

  11. A novel computer simulation method for simulating the multiscale transduction dynamics of signal proteins

    NASA Astrophysics Data System (ADS)

    Peter, Emanuel; Dick, Bernhard; Baeurle, Stephan A.

    2012-03-01

    Signal proteins are able to adapt their response to a change in the environment, governing in this way a broad variety of important cellular processes in living systems. While conventional molecular-dynamics (MD) techniques can be used to explore the early signaling pathway of these protein systems at atomistic resolution, the high computational costs limit their usefulness for the elucidation of the multiscale transduction dynamics of most signaling processes, occurring on experimental timescales. To cope with the problem, we present in this paper a novel multiscale-modeling method, based on a combination of the kinetic Monte-Carlo- and MD-technique, and demonstrate its suitability for investigating the signaling behavior of the photoswitch light-oxygen-voltage-2-Jα domain from Avena Sativa (AsLOV2-Jα) and an AsLOV2-Jα-regulated photoactivable Rac1-GTPase (PA-Rac1), recently employed to control the motility of cancer cells through light stimulus. More specifically, we show that their signaling pathways begin with a residual re-arrangement and subsequent H-bond formation of amino acids near to the flavin-mononucleotide chromophore, causing a coupling between β-strands and subsequent detachment of a peripheral α-helix from the AsLOV2-domain. In the case of the PA-Rac1 system we find that this latter process induces the release of the AsLOV2-inhibitor from the switchII-activation site of the GTPase, enabling signal activation through effector-protein binding. These applications demonstrate that our approach reliably reproduces the signaling pathways of complex signal proteins, ranging from nanoseconds up to seconds at affordable computational costs.

  12. An adaptive coarse graining method for signal transduction in three dimensions

    PubMed Central

    Archuleta, Michelle N.; McDermott, Jason E.; Edwards, Jeremy S.; Resat, Haluk

    2013-01-01

    The spatio-temporal landscape of the plasma membrane regulates activation and signal transduction of membrane bound receptors by restricting their two-dimensional mobility and by inducing receptor clustering. This regulation also extends to complex formation between receptors and adaptor proteins, which are the intermediate signaling molecules involved in cellular signaling that relay the received cues from cell surface to cytoplasm and eventually to the nucleus. Although their investigation poses challenging technical difficulties, there is a crucial need to understand the impact of the receptor diffusivity, clustering, and spatial heterogeneity, and of receptor-adaptor protein complex formation on the cellular signal transduction patterns. Building upon our earlier studies, we have developed an adaptive coarse-grained Monte Carlo method that can be used to investigate the role of diffusion, clustering and membrane corralling on receptor association and receptor-adaptor protein complex formation dynamics in three dimensions. The new Monte Carlo lattice based approach allowed us to introduce spatial resolution on the 2-D plasma membrane and to model the cytoplasm in three-dimensions. Being a multi-resolution approach, our new method makes it possible to represent various parts of the cellular system at different levels of detail and enabled us to utilize the locally homogeneous assumption when justified (e.g., cytoplasmic region away from the cell membrane) and avoid its use when high spatial resolution is needed (e.g., cell membrane and cytoplasmic region near the membrane) while keeping the required computational complexity manageable. Our results have shown that diffusion has a significant impact on receptor-receptor dimerization and receptor-adaptor protein complex formation kinetics. We have observed an “adaptor protein hopping” mechanism where the receptor binding proteins may hop between receptors to form short-lived transient complexes. This increased

  13. Peach (Prunus persica) extract inhibits angiotensin II-induced signal transduction in vascular smooth muscle cells.

    PubMed

    Kono, Ryohei; Okuno, Yoshiharu; Nakamura, Misa; Inada, Ken-ichi; Tokuda, Akihiko; Yamashita, Miki; Hidaka, Ryu; Utsunomiya, Hirotoshi

    2013-08-15

    Angiotensin II (Ang II) is a vasoactive hormone that has been implicated in cardiovascular diseases. Here, the effect of peach, Prunus persica L. Batsch, pulp extract on Ang II-induced intracellular Ca(2+) mobilization, reactive oxygen species (ROS) production and signal transduction events in cultured vascular smooth muscle cells (VSMCs) was investigated. Pretreatment of peach ethyl acetate extract inhibited Ang II-induced intracellular Ca(2+) elevation in VSMCs. Furthermore, Ang II-induced ROS generation, essential for signal transduction events, was diminished by the peach ethyl acetate extract. The peach ethyl acetate extract also attenuated the Ang II-induced phosphorylation of epidermal growth factor receptor and myosin phosphatase target subunit 1, both of which are associated with atherosclerosis and hypertension. These results suggest that peach ethyl acetate extract may have clinical potential for preventing cardiovascular diseases by interfering with Ang II-induced intracellular Ca(2+) elevation, the generation of ROS, and then blocking signal transduction events.

  14. Analysis of a signal transduction pathway involved in leaf epidermis differentiation.

    SciTech Connect

    Philip W. Becraft

    2005-05-23

    The major objective of this study was to identify and analyze signal transduction factors that function with the CR4 receptor kinase. We pursued this analysis in Arabidopsis. Analysis of other members of the ACR4 related receptor (CRR) family produced biochemical evidence consistent with some of them functioning in ACR4 signal transduction. Yeast 2-hybrid identified six proteins that interact with the cytoplasmic domain of ACR4, representing putative downstream signal transduction components. The interactions for all 6 proteins were verified by in vitro pull down assays. Five of the interacting proteins were phosphorylated by ACR4. We also identified candidate interactors with the extracellular TNFR domain. We hypothesize this may be the ligand binding domain for ACR4. In one approach, yeast 2-hybrid was again used and five candidate proteins identified. Nine additional candidates were identified in a genome wide scan of Arabidopsis amino acid sequences that threaded onto the TNF structure.

  15. Transduction of aminergic and peptidergic signals in enteric neurones of the guinea-pig.

    PubMed Central

    Palmer, J M; Wood, J D; Zafirov, D H

    1987-01-01

    1. The biogenic amines 5-hydroxytryptamine (5-HT) and histamine, and the peptides bombesin, gastrin-releasing peptide (GRP), vasoactive intestinal peptide (VIP), cholecystokinin (CCK), substance P and calcitonin gene-related peptide (CGRP) each mimicked slow synaptic excitation (slow e.p.s.p.) when applied to myenteric neurones of the guinea-pig small intestine. 2. Stimulation of the catalytic activity of adenylate cyclase by forskolin and intraneuronal elevation of cyclic 3',5'-adenosine monophosphate (cyclic AMP) also mimicked the slow e.p.s.p. and the actions of the aminergic and peptidergic messengers. 3. Adenosine prevented stimulation of adenylate cyclase by forskolin and abolished the slow e.p.s.p.-like actions of forskolin. 4. Exposure of the neurones to adenosine prior to or during application of bombesin, GRP, VIP, CCK or histamine blocked the actions of these substances. 5. Pre-treatment with adenosine did not suppress the slow e.p.s.p.-like actions of substance P, CGRP or 5-HT. 6. The results suggest that signal transduction for bombesin, GRP, VIP, CCK and histamine involves stimulation of adenylate cyclase and second messenger function of cyclic AMP. Transduction mechanisms for 5-HT, substance P and CGRP appear not to involve second messenger function of cyclic AMP. PMID:3656177

  16. Discovery of GPCR ligands for probing signal transduction pathways

    PubMed Central

    Brogi, Simone; Tafi, Andrea; Désaubry, Laurent; Nebigil, Canan G.

    2014-01-01

    G protein-coupled receptors (GPCRs) are seven integral transmembrane proteins that are the primary targets of almost 30% of approved drugs and continue to represent a major focus of pharmaceutical research. All of GPCR targeted medicines were discovered by classical medicinal chemistry approaches. After the first GPCR crystal structures were determined, the docking screens using these structures lead to discovery of more novel and potent ligands. There are over 360 pharmaceutically relevant GPCRs in the human genome and to date about only 30 of structures have been determined. For these reasons, computational techniques such as homology modeling and molecular dynamics simulations have proven their usefulness to explore the structure and function of GPCRs. Furthermore, structure-based drug design and in silico screening (High Throughput Docking) are still the most common computational procedures in GPCRs drug discovery. Moreover, ligand-based methods such as three-dimensional quantitative structure–selectivity relationships, are the ideal molecular modeling approaches to rationalize the activity of tested GPCR ligands and identify novel GPCR ligands. In this review, we discuss the most recent advances for the computational approaches to effectively guide selectivity and affinity of ligands. We also describe novel approaches in medicinal chemistry, such as the development of biased agonists, allosteric modulators, and bivalent ligands for class A GPCRs. Furthermore, we highlight some knockout mice models in discovering biased signaling selectivity. PMID:25506327

  17. An electrochemical amplification immunoassay using bi-electrode signal transduction system.

    PubMed

    Chen, Zhao-Peng; Jiang, Jian-Hui; Zhang, Xiao-Bing; Shen, Guo-Li; Yu, Ru-Qin

    2007-03-30

    An electrochemical immunoassay technique has been developed based on the sensitive detection of the enzyme-generated product with a bi-electrode signal transduction system. The system uses two separate electrodes, an immunoelectrode and a detection electrode to form a galvanic cell to implement the redox reactions on two different electrodes, that is the enzyme-generated reductant in the anode region is electrochemically oxidized by an oxidant (silver ions) in the cathode apartment. Based on a sandwich procedure, after immunoelectrode with antibody immobilized on its surface bound with the corresponding antigen and alkaline phosphatase conjugated antibody successively, the immunoelectrode was placed in enzyme reaction solution and wired to the detection electrode which was immerged into a silver deposition solution. These two solutions are connected with a salt bridge. Thus a bi-electrode signal transduction system device is constructed in which the immunoelectrode acts as anode and the detection electrode serves as cathode. The enzyme bound on the anode surface initiates the hydrolysis of ascorbic acid 2-phosphate to produce ascorbic acid in the anode region. The ascorbic acid produced in the anodic apartment is electrochemically oxidized by silver ions coupled with the deposition of silver metal on the cathode. Via a period of 30min deposition, silver will deposited on the detection electrode in an amount corresponding to the quantity of ascorbic acid produced, leading to a great enhancement in the electrochemical stripping signal due to the accumulation of metallic silver by enzyme-generated product. Compared with the method using chemical deposition of silver, the electrochemical deposition of silver on a separate detection electrode apartment avoids the possible influence of silver deposition on the enzyme activity.

  18. Costal2 Functions as a Microtubule-Dependent Motor in the Hedgehog Signal Transduction Pathway

    PubMed Central

    Farzan, Shohreh F.; Ascano, Manuel; Ogden, Stacey K.; Sanial, Matthieu; Brigui, Amira; Plessis, Anne; Robbins, David J.

    2009-01-01

    SUMMARY The Hedgehog (Hh) signaling pathway initiates an evolutionarily conserved developmental program required for the proper patterning of many tissues. Costal2 (Cos2) is a requisite component of the Hh pathway, whose mechanistic role is not well understood. Cos2 was initially predicted, based on its primary sequence, to function as a microtubule-associated (MT) molecular motor. However, despite being identified over a decade ago, evidence showing that Cos2 function might require kinesin-like properties has for the most part been lacking. Thus the prevailing dogma in the field is that Cos2 functions solely as a scaffolding protein during Hh signal transduction. Here, we provide the first evidence that Cos2 motility is required for its biological function, and that this motility may be Hh regulated. We show that Cos2 motility requires an active motor domain, ATP and microtubules. Additionally, Cos2 recruits and transports other components of the Hh signaling pathway, including the transcription factor Cubitus interruptus (Ci), throughout the cell. Drosophila expressing cos2 mutations that encode proteins that lack motility are attenuated in their ability to regulate Ci activity and exhibit phenotypes consistent with attenuated Cos2 function. Combined, these results demonstrate that Cos2 motility plays an important role in its function, regulating the amounts and activity of Ci that ultimately interpret the level of Hh to which cells are exposed. PMID:18691888

  19. Effects of low-energy electromagnetic fields (pulsed and DC) on membrane signal transduction processes in biological systems

    SciTech Connect

    Luben, R.A. )

    1991-07-01

    The vertebrate organism possesses a number of internal processes for signaling and communication between cell types. Hormones and neurotransmitters move from one cell type to another and carry chemical messages that modulate the metabolic responses of tissues to the environment. Interaction with these signaling systems is a potential mechanism by which very low-energy electromagnetic fields might produce metabolic responses in the body. Hormone and neurotransmitter receptors are specialized protein molecules that use a variety of biochemical activities to pass chemical signals from the outside of a cell across the plasma membrane to the interior of the cell. Since many low-energy electromagnetic fields have too little energy to directly traverse the membrane, it is possible that they may modify the existing signal transduction processes in cell membranes, thus producing both transduction and biochemical amplification of the effects of the field itself. As an example of the kinds of processes that may be involved in these interactions, one metabolic process in which the physiological effects of low-energy electromagnetic fields is well established is the healing of bone fractures. The process of regulation of bone turnover and healing is reviewed in the context of clinical applications of electromagnetic energy to the healing process, especially for persistent nonunion fractures. A hypothetical molecular mechanism is presented that might account for the observed effects of electromagnetic fields on bone cell metabolism in terms of the fields' interference with signal transduction events involved in the hormonal regulation of osteoblast function and differentiation. 88 refs.

  20. Targeting prostate cancer based on signal transduction and cell cycle pathways

    PubMed Central

    Lee, John T.; Lehmann, Brian D.; Terrian, David M.; Chappell, William H.; Stivala, Franca; Libra, Massimo; Martelli, Alberto M.; Steelman, Linda S.

    2008-01-01

    Prostate cancer remains a leading cause of death in men despite increased capacity to diagnose at earlier stages. After prostate cancer has become hormone independent, which often occurs after hormonal ablation therapies, it is difficult to effectively treat. Prostate cancer may arise from mutations and dysregulation of various genes involved in regulation signal transduction (e.g., PTEN, Akt, etc.,) and the cell cycle (e.g., p53, p21Cip1, p27Kip1, Rb, etc.,). This review focuses on the aberrant interactions of signal transduction and cell cycle genes products and how they can contribute to prostate cancer and alter therapeutic effectiveness. PMID:18594202

  1. [Signal transduction and drug resistance in Mycobacterium tuberculosis--A review].

    PubMed

    Wang, Shanshan; Feng, Yi; Zhang, Zhe

    2015-08-01

    Mycobacterium tuberculosis infection kills two million people every year, and the chemotherapy has led to significant amount of drug resistance. Signal transduction systems are used by bacteria to survive or adapt to their living environment, but the relationship to drug resistance is not well understood. In this article, we introduced the two-component signal transduction systems of M. tuberculosis and analyzed their relationship with drug resistance. We identified five two-component system pairs involved in the formation of drug resistance. Therefore, these two-component systems are good targeting sites for small biochemical drugs to target so as to reverse the drug resistance and virulence.

  2. Signal Transduction Pathways that Regulate CAB Gene Expression

    SciTech Connect

    Chory, Joanne

    2004-12-31

    The process of chloroplast differentiation, involves the coordinate regulation of many nuclear and chloroplast genes. The cues for the initiation of this developmental program are both extrinsic (e.g., light) and intrinsic (cell-type and plastid signals). During this project period, we utilized a molecular genetic approach to select for Arabidopsis mutants that did not respond properly to environmental light conditions, as well as mutants that were unable to perceive plastid damage. These latter mutants, called gun mutants, define two retrograde signaling pathways that regulate nuclear gene expression in response to chloroplasts. A major finding was to identify a signal from chloroplasts that regulates nuclear gene transcription. This signal is the build-up of Mg-Protoporphyrin IX, a key intermediate of the chlorophyll biosynthetic pathway. The signaling pathways downstream of this signal are currently being studied. Completion of this project has provided an increased understanding of the input signals and retrograde signaling pathways that control nuclear gene expression in response to the functional state of chloroplasts. These studies should ultimately influence our abilities to manipulate plant growth and development, and will aid in the understanding of the developmental control of photosynthesis.

  3. Signal Transduction Pathways that Regulate CAB Gene Expression

    SciTech Connect

    Chory, Joanne

    2006-01-16

    The process of chloroplast differentiation, involves the coordinate regulation of many nuclear and chloroplast genes. The cues for the initiation of this developmental program are both extrinsic (e.g., light) and intrinsic (cell-type and plastid signals). During this project period, we utilized a molecular genetic approach to select for Arabidopsis mutants that did not respond properly to environmental light conditions, as well as mutants that were unable to perceive plastid damage. These latter mutants, called gun mutants, define two retrograde signaling pathways that regulate nuclear gene expression in response to chloroplasts. A major finding was to identify a signal from chloroplasts that regulates nuclear gene transcription. This signal is the build-up of Mg-Protoporphyrin IX, a key intermediate of the chlorophyll biosynthetic pathway. The signaling pathways downstream of this signal are currently being studied. Completion of this project has provided an increased understanding of the input signals and retrograde signaling pathways that control nuclear gene expression in response to the functional state of chloroplasts. These studies should ultimately influence our abilities to manipulate plant growth and development, and will aid in the understanding of the developmental control of photosynthesis.

  4. Molecular mechanisms of gravity perception and signal transduction in plants.

    PubMed

    Kolesnikov, Yaroslav S; Kretynin, Serhiy V; Volotovsky, Igor D; Kordyum, Elizabeth L; Ruelland, Eric; Kravets, Volodymyr S

    2016-07-01

    Gravity is one of the environmental cues that direct plant growth and development. Recent investigations of different gravity signalling pathways have added complexity to how we think gravity is perceived. Particular cells within specific organs or tissues perceive gravity stimulus. Many downstream signalling events transmit the perceived information into subcellular, biochemical, and genomic responses. They are rapid, non-genomic, regulatory, and cell-specific. The chain of events may pass by signalling lipids, the cytoskeleton, intracellular calcium levels, protein phosphorylation-dependent pathways, proteome changes, membrane transport, vacuolar biogenesis mechanisms, or nuclear events. These events culminate in changes in gene expression and auxin lateral redistribution in gravity response sites. The possible integration of these signalling events with amyloplast movements or with other perception mechanisms is discussed. Further investigation is needed to understand how plants coordinate mechanisms and signals to sense this important physical factor.

  5. Signal Transduction in the Chronic Leukemias: Implications for Targeted Therapies

    PubMed Central

    Ahmed, Wesam; Van Etten, Richard A.

    2013-01-01

    The chronic leukemias, including chronic myeloid leukemia (CML), the Philadelphia-negative myeloproliferative neoplasms (MPNs), and chronic lymphocytic leukemia (CLL), have been characterized extensively for abnormalities of cellular signaling pathways. This effort has led to the elucidation of the central role of dysregulated tyrosine kinase signaling in the chronic myeloid neoplasms and of constitutive B-cell receptor signaling in CLL. This, in turn, has stimulated the development of small molecule inhibitors of these signaling pathways for therapy of chronic leukemia. Although the field is still in its infancy, the clinical results with these agents have ranged from encouraging (CLL) to spectacular (CML). In this review, we summarize recent studies that have helped to define the signaling pathways critical to the pathogenesis of the chronic leukemias. We also discuss correlative studies emerging from clinical trials of drugs targeting these pathways. PMID:23307472

  6. Molecular mechanisms of gravity perception and signal transduction in plants.

    PubMed

    Kolesnikov, Yaroslav S; Kretynin, Serhiy V; Volotovsky, Igor D; Kordyum, Elizabeth L; Ruelland, Eric; Kravets, Volodymyr S

    2016-07-01

    Gravity is one of the environmental cues that direct plant growth and development. Recent investigations of different gravity signalling pathways have added complexity to how we think gravity is perceived. Particular cells within specific organs or tissues perceive gravity stimulus. Many downstream signalling events transmit the perceived information into subcellular, biochemical, and genomic responses. They are rapid, non-genomic, regulatory, and cell-specific. The chain of events may pass by signalling lipids, the cytoskeleton, intracellular calcium levels, protein phosphorylation-dependent pathways, proteome changes, membrane transport, vacuolar biogenesis mechanisms, or nuclear events. These events culminate in changes in gene expression and auxin lateral redistribution in gravity response sites. The possible integration of these signalling events with amyloplast movements or with other perception mechanisms is discussed. Further investigation is needed to understand how plants coordinate mechanisms and signals to sense this important physical factor. PMID:26215561

  7. Epidermal growth factor stimulates proliferation and migration of porcine trophectoderm cells through protooncogenic protein kinase 1 and extracellular-signal-regulated kinases 1/2 mitogen-activated protein kinase signal transduction cascades during early pregnancy.

    PubMed

    Jeong, Wooyoung; Kim, Jinyoung; Bazer, Fuller W; Song, Gwonhwa

    2013-12-01

    For successful implantation and establishment of early epitheliochorial placentation, porcine conceptuses require histotroph, including nutrients and growth factors, secreted by or transported into the lumen of the uterus. Epidermal growth factor (EGF), an essential component of histotroph, is known to have potential growth-promoting activities on the conceptus and uterine endometrium. However, little is known about its effects to transactivate cell signaling cascades responsible for proliferation, growth and differentiation of conceptus trophectoderm. In the present study, therefore, we determined that EGFR mRNA and protein were abundant in endometrial luminal and glandular epithelia, stratum compactum stroma and conceptus trophectoderm on days 13-14 of pregnancy, but not in any other cells of the uterus or conceptus. In addition, primary porcine trophectoderm (pTr) cells treated with EGF exhibited increased abundance of phosphorylated (p)-AKT1, p-ERK1/2 MAPK and p-P90RSK over basal levels within 5min, and effect that was maintained to between 30 and 120min. Immunofluorescence microscopy revealed abundant amounts of p-ERK1/2 MAPK and p-AKT1 proteins in the nucleus and, to a lesser extent, in the cytoplasm of pTr cells treated with EGF as compared to control cells. Furthermore, the abundance of p-AKT1 and p-ERK1/2 MAPK proteins was inhibited in control and EGF-treated pTr cells transfected with EGFR siRNA. Compared to the control siRNA transfected pTr cells, pTr cells transfected with EGFR siRNA exhibited an increase in expression of IFND and TGFB1, but there was no effect of expression of IFNG. Further, EGF stimulated proliferation and migration of pTr cells through activation of the PI3K-AKT1 and ERK1/2 MAPK-P90RSK cell signaling pathways. Collectively, these results support the hypothesis that EGF coordinately activates multiple cell signaling pathways critical to proliferation, migration and survival of trophectoderm cells that are critical to development of

  8. Physician Education: The Erythropoietin Receptor and Signal Transduction.

    PubMed

    Yoshimura; Arai

    1996-01-01

    receptor gene was cloned by D'Andrea and coworkers in 1989 from murine erythroleukemia cells [1]. It became clear that the EPO receptor belongs to the cytokine receptor family that comprises receptors for the various interleukins, GM-CSF, granulocyte colony-stimulating factor (G-CSF), growth hormone and prolactin. The special characteristic of this family of receptors is that they are switched on (i.e., the receptor is activated) and transduce signals to the interior of the cell by the formation of homo- or hetero-oligomers (dimers or trimers). Moreover, hetero-oligomers of these receptors share a common receptor subunit. As shown in Figure 2, the IL-3, IL-5 and GM-CSF receptors have a common &bgr; subunit, and their ligand specificity is determined by the &agr; subunit. In the same manner, the IL-6, LIF and oncostatin M (OSM) receptors all share gp130, which is the &bgr; subunit of the IL-6 receptor. The IL-2, IL-4 and IL-7 receptors all share the &ggr; subunit of the IL-2 receptor. All the above receptors are activated by the formation of hetero-oligomers, but the G-CSF receptor, EPO receptor, and growth hormone receptor are activated by the formation of homodimers of the same types of molecules [2]. We can see that groups of cytokines such as the interleukins that affect a relatively wide range of cells and have redundant biological activity create this redundancy through the common use of a single receptor subunit. On the other hand, EPO and G-CSF act with high specificity on a relatively limited range of cells, so it was probably unnecessary for their receptors to share one of the subunits. EPO RECEPTOR AND JAK2 KINASE: The signal for cellular proliferation and differentiation into erythroblasts is thought to originate at the EPO receptor. The cytoplasmic domain of the EPO receptor can be divided into two major regions. Roughly half of the cytoplasmic domain, the part lying nearest the plasma membrane, is required for generating the signals for proliferation and

  9. Common Extracellular Sensory Domains in Transmembrane Receptors for Diverse Signal Transduction Pathways in Bacteria and Archaea

    PubMed Central

    Zhulin, Igor B.; Nikolskaya, Anastasia N.; Galperin, Michael Y.

    2003-01-01

    Transmembrane receptors in microorganisms, such as sensory histidine kinases and methyl-accepting chemotaxis proteins, are molecular devices for monitoring environmental changes. We report here that sensory domain sharing is widespread among different classes of transmembrane receptors. We have identified two novel conserved extracellular sensory domains, named CHASE2 and CHASE3, that are found in at least four classes of transmembrane receptors: histidine kinases, adenylate cyclases, predicted diguanylate cyclases, and either serine/threonine protein kinases (CHASE2) or methyl-accepting chemotaxis proteins (CHASE3). Three other extracellular sensory domains were shared by at least two different classes of transmembrane receptors: histidine kinases and either diguanylate cyclases, adenylate cyclases, or phosphodiesterases. These observations suggest that microorganisms use similar conserved domains to sense similar environmental signals and transmit this information via different signal transduction pathways to different regulatory circuits: transcriptional regulation (histidine kinases), chemotaxis (methyl-accepting proteins), catabolite repression (adenylate cyclases), and modulation of enzyme activity (diguanylate cyclases and phosphodiesterases). The variety of signaling pathways using the CHASE-type domains indicates that these domains sense some critically important extracellular signals. PMID:12486065

  10. Role of the Transporter-Like Sensor Kinase CbrA in Histidine Uptake and Signal Transduction

    PubMed Central

    Gauntlett, Jonathan C.; Oldenburg, Darby G.; Cook, Gregory M.; Rainey, Paul B.

    2015-01-01

    ABSTRACT CbrA is an atypical sensor kinase found in Pseudomonas. The autokinase domain is connected to a putative transporter of the sodium/solute symporter family (SSSF). CbrA functions together with its cognate response regulator, CbrB, and plays an important role in nutrient acquisition, including regulation of hut genes for the utilization of histidine and its derivative, urocanate. Here we report on the findings of a genetic and biochemical analysis of CbrA with a focus on the function of the putative transporter domain. The work was initiated with mutagenesis of histidine uptake-proficient strains to identify histidine-specific transport genes located outside the hut operon. Genes encoding transporters were not identified, but mutations were repeatedly found in cbrA. This, coupled with the findings of [3H]histidine transport assays and further mutagenesis, implicated CbrA in histidine uptake. In addition, mutations in different regions of the SSSF domain abolished signal transduction. Site-specific mutations were made at four conserved residues: W55 and G172 (SSSF domain), H766 (H box), and N876 (N box). The mutations W55G, G172H, and N876G compromised histidine transport but had minimal effects on signal transduction. The H766G mutation abolished both transport and signal transduction, but the capacity to transport histidine was restored upon complementation with a transport-defective allele of CbrA, most likely due to interdomain interactions. Our combined data implicate the SSSF domain of CbrA in histidine transport and suggest that transport is coupled to signal transduction. IMPORTANCE Nutrient acquisition in bacteria typically involves membrane-bound sensors that, via cognate response regulators, determine the activity of specific transporters. However, nutrient perception and uptake are often coupled processes. Thus, from a physiological perspective, it would make sense for systems that couple the process of signaling and transport within a single

  11. Structure and mechanism of the essential two-component signal-transduction system WalKR in Staphylococcus aureus

    DOE PAGES

    Ji, Quanjiang; Chen, Peter J.; Qin, Guangrong; Deng, Xin; Hao, Ziyang; Wawrzak, Zdzislaw; Yeo, Won -Sik; Quang, Jenny Winjing; Cho, Hoonsik; Luo, Guan -Zheng; et al

    2016-03-18

    Most low GC Gram-positive bacteria possess an essential walKR two-component system (TCS) for signal transduction involved in regulating cell wall homoeostasis. Despite the well-established intracellular regulatory mechanism, the role of this TCS in extracellular signal recognition and factors that modulate the activity of this TCS remain largely unknown. Here we identify the extracellular receptor of the kinase ‘WalK’ (erWalK) as a key hub for bridging extracellular signal input and intracellular kinase activity modulation in Staphylococcus aureus. Characterization of the crystal structure of erWalK revealed a canonical Per-Arnt-Sim (PAS) domain for signal sensing. Single amino-acid mutation of potential signal-transduction residues resultedmore » in severely impaired function of WalKR. A small molecule derived from structure-based virtual screening against erWalK is capable of selectively activating the walKR TCS. Lastly, the molecular level characterization of erWalK will not only facilitate exploration of natural signal(s) but also provide a template for rational design of erWalK inhibitors.« less

  12. Structure and mechanism of the essential two-component signal-transduction system WalKR in Staphylococcus aureus

    PubMed Central

    Ji, Quanjiang; Chen, Peter J.; Qin, Guangrong; Deng, Xin; Hao, Ziyang; Wawrzak, Zdzislaw; Yeo, Won-Sik; Quang, Jenny Winjing; Cho, Hoonsik; Luo, Guan-Zheng; Weng, Xiaocheng; You, Qiancheng; Luan, Chi-Hao; Yang, Xiaojing; Bae, Taeok; Yu, Kunqian; Jiang, Hualiang; He, Chuan

    2016-01-01

    Most low GC Gram-positive bacteria possess an essential walKR two-component system (TCS) for signal transduction involved in regulating cell wall homoeostasis. Despite the well-established intracellular regulatory mechanism, the role of this TCS in extracellular signal recognition and factors that modulate the activity of this TCS remain largely unknown. Here we identify the extracellular receptor of the kinase ‘WalK' (erWalK) as a key hub for bridging extracellular signal input and intracellular kinase activity modulation in Staphylococcus aureus. Characterization of the crystal structure of erWalK revealed a canonical Per-Arnt-Sim (PAS) domain for signal sensing. Single amino-acid mutation of potential signal-transduction residues resulted in severely impaired function of WalKR. A small molecule derived from structure-based virtual screening against erWalK is capable of selectively activating the walKR TCS. The molecular level characterization of erWalK will not only facilitate exploration of natural signal(s) but also provide a template for rational design of erWalK inhibitors. PMID:26987594

  13. Signal Transduction: Turning a Switch into a Rheostat

    PubMed Central

    Bardwell, Lee

    2010-01-01

    MAP kinase cascades are inherently switch-like, but, during yeast mating, MAPK signaling is graded. A new study suggests that the Ste5 scaffold protein is responsible for making this switch less switch-like. PMID:18957235

  14. Light signal transduction: an infinite spectrum of possibilities

    PubMed Central

    Chory, Joanne

    2011-01-01

    SUMMARY The past 30 years has seen a tremendous increase in our understanding of the light-signaling networks of higher plants. This short review emphasizes the role that Arabidopsis genetics has played in deciphering this complex network. Importantly, it outlines how genetic studies led to the identification of photoreceptors and signaling components that are not only relevant in plants, but play key roles in mammals. PMID:20409272

  15. Role of inorganic polyphosphate in mammalian cells: from signal transduction and mitochondrial metabolism to cell death.

    PubMed

    Angelova, Plamena R; Baev, Artyom Y; Berezhnov, Alexey V; Abramov, Andrey Y

    2016-02-01

    Inorganic polyphosphate (polyP) is a polymer compromised of linearly arranged orthophosphate units that are linked through high-energy phosphoanhydride bonds. The chain length of this polymer varies from five to several thousand orthophosphates. PolyP is distributed in the most of the living organisms and plays multiple functions in mammalian cells, it is important for blood coagulation, cancer, calcium precipitation, immune response and many others. Essential role of polyP is shown for mitochondria, from implication into energy metabolism and mitochondrial calcium handling to activation of permeability transition pore (PTP) and cell death. PolyP is a gliotransmitter which transmits the signal in astrocytes via activation of P2Y1 receptors and stimulation of phospholipase C. PolyP-induced calcium signal in astrocytes can be stimulated by different lengths of this polymer but only long chain polyP induces mitochondrial depolarization by inhibition of respiration and opening of the PTP. It leads to induction of astrocytic cell death which can be prevented by inhibition of PTP with cyclosporine A. Thus, medium- and short-length polyP plays role in signal transduction and mitochondrial metabolism of astrocytes and long chain of this polymer can be toxic for the cells. PMID:26862186

  16. Signal transduction across alamethicin ion channels in the presence of noise.

    PubMed Central

    Bezrukov, S M; Vodyanoy, I

    1997-01-01

    We have studied voltage-dependent ion channels of alamethicin reconstituted into an artificial planar lipid bilayer membrane from the point of view of electric signal transduction. Signal transduction properties of these channels are highly sensitive to the external electric noise. Specifically, addition of bandwidth-restricted "white" noise of 10-20 mV (r.m.s.) to a small sine wave input signal increases the output signal by approximately 20-40 dB conserving, and even slightly increasing, the signal-to-noise ratio at the system output. We have developed a small-signal adiabatic theory of stochastic resonance for a threshold-free system of voltage-dependent ion channels. This theory describes our main experimental findings giving good qualitative understanding of the underlying mechanism. It predicts the right value of the output signal-to-noise ratio and provides a reliable estimate for the noise intensity corresponding to its maximum. Our results suggest that the alamethicin channel in a lipid bilayer is a good model system for studies of mechanisms of primary electrical signal processing in biology showing an important feature of signal transduction improvement by a fluctuating environment. Images FIGURE 1 PMID:9370439

  17. The relation of signal transduction to the sensitivity and dynamic range of bacterial chemotaxis.

    PubMed

    Namba, Toshinori; Nishikawa, Masatoshi; Shibata, Tatsuo

    2012-09-19

    Complex networks of interacting molecular components of living cells are responsible for many important processes, such as signal processing and transduction. An important challenge is to understand how the individual properties of these molecular interactions and biochemical transformations determine the system-level properties of biological functions. Here, we address the issue of the accuracy of signal transduction performed by a bacterial chemotaxis system. The chemotaxis sensitivity of bacteria to a chemoattractant gradient has been measured experimentally from bacterial aggregation in a chemoattractant-containing capillary. The observed precision of the chemotaxis depended on environmental conditions such as the concentration and molecular makeup of the chemoattractant. In a quantitative model, we derived the chemotactic response function, which is essential to describing the signal transduction process involved in bacterial chemotaxis. In the presence of a gradient, an analytical solution is derived that reveals connections between the chemotaxis sensitivity and the characteristics of the signaling system, such as reaction rates. These biochemical parameters are integrated into two system-level parameters: one characterizes the efficiency of gradient sensing, and the other is related to the dynamic range of chemotaxis. Thus, our approach explains how a particular signal transduction property affects the system-level performance of bacterial chemotaxis. We further show that the two parameters can be derived from published experimental data from a capillary assay, which successfully characterizes the performance of bacterial chemotaxis.

  18. The relation of signal transduction to the sensitivity and dynamic range of bacterial chemotaxis.

    PubMed

    Namba, Toshinori; Nishikawa, Masatoshi; Shibata, Tatsuo

    2012-09-19

    Complex networks of interacting molecular components of living cells are responsible for many important processes, such as signal processing and transduction. An important challenge is to understand how the individual properties of these molecular interactions and biochemical transformations determine the system-level properties of biological functions. Here, we address the issue of the accuracy of signal transduction performed by a bacterial chemotaxis system. The chemotaxis sensitivity of bacteria to a chemoattractant gradient has been measured experimentally from bacterial aggregation in a chemoattractant-containing capillary. The observed precision of the chemotaxis depended on environmental conditions such as the concentration and molecular makeup of the chemoattractant. In a quantitative model, we derived the chemotactic response function, which is essential to describing the signal transduction process involved in bacterial chemotaxis. In the presence of a gradient, an analytical solution is derived that reveals connections between the chemotaxis sensitivity and the characteristics of the signaling system, such as reaction rates. These biochemical parameters are integrated into two system-level parameters: one characterizes the efficiency of gradient sensing, and the other is related to the dynamic range of chemotaxis. Thus, our approach explains how a particular signal transduction property affects the system-level performance of bacterial chemotaxis. We further show that the two parameters can be derived from published experimental data from a capillary assay, which successfully characterizes the performance of bacterial chemotaxis. PMID:22995512

  19. The information highways of a biotechnological workhorse – signal transduction in Hypocrea jecorina

    PubMed Central

    Schmoll, Monika

    2008-01-01

    Background The ascomycete Hypocrea jecorina (anamorph Trichoderma reesei) is one of the most prolific producers of biomass-degrading enzymes and frequently termed an industrial workhorse. To compete for nutrients in its habitat despite its shortcoming in certain degradative enzymes, efficient perception and interpretation of environmental signals is indispensable. A better understanding of these signals as well as their transmission machinery can provide sources for improvement of biotechnological processes. Results The genome of H. jecorina was analysed for the presence and composition of common signal transduction pathways including heterotrimeric G-protein cascades, cAMP signaling, mitogen activated protein kinases, two component phosphorelay systems, proteins involved in circadian rhythmicity and light response, calcium signaling and the superfamily of Ras small GTPases. The results of this survey are discussed in the context of current knowledge in order to assess putative functions as well as potential impact of alterations of the respective pathways. Conclusion Important findings include an additional, bacterial type phospholipase C protein and an additional 6-4 photolyase. Moreover the presence of 4 RGS-(Regulator of G-protein Signaling) proteins and 3 GprK-type G-protein coupled receptors comprising an RGS-domain suggest a more complex posttranslational regulation of G-protein signaling than in other ascomycetes. Also the finding, that H. jecorina, unlike yeast possesses class I phosducins which are involved in phototransduction in mammals warrants further investigation. An alteration in the regulation of circadian rhythmicity may be deduced from the extension of both the class I and II of casein kinases, homologues of which are implicated in phosphorylation of FRQ in Neurospora crassa. On the other hand, a shortage in the number of the pathogenicity related PTH11-type G-protein coupled receptors (GPCRs) as well as a lack of microbial opsins was detected

  20. Signal transduction in responses to UV-B radiation.

    PubMed

    Jenkins, Gareth I

    2009-01-01

    UV-B radiation is a key environmental signal that initiates diverse responses in plants that affect metabolism, development, and viability. Many effects of UV-B involve the differential regulation of gene expression. The response to UV-B depends on the nature of the UV-B treatment, the extent of adaptation and acclimation to UV-B, and interaction with other environmental factors. Responses to UV-B are mediated by both nonspecific signaling pathways, involving DNA damage, reactive oxygen species, and wound/defense signaling molecules, and UV-B-specific pathways that mediate photomorphogenic responses to low levels of UV-B. Importantly, photomorphogenic signaling stimulates the expression of genes involved in UV-protection and hence promotes plant survival in UV-B. Photomorphogenic UV-B signaling is mediated by the UV-B-specific component UV RESISTANCE LOCUS8 (UVR8). Both UVR8 and CONSTITUTIVE PHOTOMORPHOGENESIS1 (COP1) are required for UV-B-induced expression of the ELONGATED HYPOCOTYL5 (HY5) transcription factor, which plays a central role in the regulation of genes involved in photomorphogenic UV-B responses.

  1. Knowledge representation model for systems-level analysis of signal transduction networks.

    PubMed

    Lee, Dong-Yup; Zimmer, Ralf; Lee, Sang-Yup; Hanisch, Daniel; Park, Sunwon

    2004-01-01

    A Petri-net based model for knowledge representation has been developed to describe as explicitly and formally as possible the molecular mechanisms of cell signaling and their pathological implications. A conceptual framework has been established for reconstructing and analyzing signal transduction networks on the basis of the formal representation. Such a conceptual framework renders it possible to qualitatively understand the cell signaling behavior at systems-level. The mechanisms of the complex signaling network are explored by applying the established framework to the signal transduction induced by potent proinflammatory cytokines, IL-1beta and TNF-alpha The corresponding expert-knowledge network is constructed to evaluate its mechanisms in detail. This strategy should be useful in drug target discovery and its validation.

  2. Signal Transduction Pathways of EMT Induced by TGF-β, SHH, and WNT and Their Crosstalks

    PubMed Central

    Zhang, Jingyu; Tian, Xiao-Jun; Xing, Jianhua

    2016-01-01

    Epithelial-to-mesenchymal transition (EMT) is a key step in development, wound healing, and cancer development. It involves cooperation of signaling pathways, such as transformation growth factor-β (TGF-β), Sonic Hedgehog (SHH), and WNT pathways. These signaling pathways crosstalk to each other and converge to key transcription factors (e.g., SNAIL1) to initialize and maintain the process of EMT. The functional roles of multi-signaling pathway crosstalks in EMT are sophisticated and, thus, remain to be explored. In this review, we focused on three major signal transduction pathways that promote or regulate EMT in carcinoma. We discussed the network structures, and provided a brief overview of the current therapy strategies and drug development targeted to these three signal transduction pathways. Finally, we highlighted systems biology approaches that can accelerate the process of deconstructing complex networks and drug discovery. PMID:27043642

  3. Signal transduction in inflammatory processes, current and future therapeutic targets: a mini review.

    PubMed

    Witkamp, R; Monshouwer, M

    2000-01-01

    The selective control of inflammatory reactions will continue to be a major issue in the development of new drugs. Many new molecular targets are coming up. This paper highlights a few key mediators that are nowadays considered as interesting therapeutic intervention points. Cytokines play an important regulatory role in the initiation, maintenance and termination of inflammatory reactions. More than 50 cytokines have been identified, and more and more has become known about their receptors and signal transduction pathways. Tumour necrosis factor-alpha (TNF-alpha) is still regarded as one of the initial cytokines of the cascade, and different approaches are followed to control its synthesis, release or effects. Lipopolysaccharide (LPS) is a one of the triggers that is able to induce a strong TNF-response. Inhibitors of cyclic nucleotide phosphodiesterases (PDEs), including rolipram and pentoxifylline suppress the LPS-induced TNF-alpha production in monocytes/macrophages. In our laboratory it has been shown that the alternative way to increase cAMP levels, via stimulation of beta-adrenergic receptors, also provides an effective way, both in vitro and in vivo, to inhibit TNF-alpha release. Other therapeutic ways include the use of antibodies directed to cytokines, TNF receptor fused to IgG, antibody therapy against TNF, the use of MAP kinase inhibitors. The different signal transduction pathways, including the NF-kappa B activation route may provide alternative pharmacological tools. We may surely expect anti-inflammatory drugs of much greater specificity to be developed in the next decade. Despite the relative limited investments in veterinary drug development this will also have consequences for veterinary therapy. PMID:10682381

  4. Fyn is a redox sensor involved in solar ultraviolet light-induced signal transduction in skin carcinogenesis

    PubMed Central

    Kim, Jong-Eun; Roh, Eunmiri; Lee, Mee Hyun; Yu, Dong Hoon; Kim, Dong Joon; Lim, Tae-Gyu; Jung, Sung Keun; Peng, Cong; Cho, Yong-Yeon; Dickinson, Sally; Alberts, Dave; Bowden, G. Tim; Einspahr, Janine; Stratton, Steven P; Curiel, Clara; Bode, Ann M.; Lee, Ki Won; Dong, Zigang

    2015-01-01

    Solar ultraviolet (UV) light is a major etiological factor in skin carcinogenesis, with solar UV-stimulated signal transduction inducing pathological changes and skin damage. The primary sensor of solar UV-induced cellular signaling has not been identified. We use an experimental system of solar simulated light (SSL) to mimic solar UV and we demonstrate that Fyn is a primary redox sensor involved in SSL-induced signal transduction. Reactive oxygen species (ROS) generated by SSL exposure directly oxidize Cys488 of Fyn, resulting in increased Fyn kinase activity. Fyn oxidation was increased in mouse skin after SSL exposure, and Fyn knockout (Fyn−/−) mice formed larger and more tumors compared to Fyn wildtype mice when exposed to SSL for an extended period of time. Murine embryonic fibroblasts (MEFs) lacking Fyn as well as cells in which Fyn expression was knocked down were resistant to SSL-induced apoptosis. Furthermore, cells expressing mutant Fyn (C448A) were resistant to SSL-induced apoptosis. These findings suggest that Fyn acts as a regulatory nexus between solar UV, ROS and signal transduction during skin carcinogenesis. PMID:26686094

  5. Fyn is a redox sensor involved in solar ultraviolet light-induced signal transduction in skin carcinogenesis.

    PubMed

    Kim, J-E; Roh, E; Lee, M H; Yu, D H; Kim, D J; Lim, T-G; Jung, S K; Peng, C; Cho, Y-Y; Dickinson, S; Alberts, D; Bowden, G T; Einspahr, J; Stratton, S P; Curiel-Lewandrowski, C; Bode, A M; Lee, K W; Dong, Z

    2016-08-01

    Solar ultraviolet (UV) light is a major etiological factor in skin carcinogenesis, with solar UV-stimulated signal transduction inducing pathological changes and skin damage. The primary sensor of solar UV-induced cellular signaling has not been identified. We use an experimental system of solar simulated light (SSL) to mimic solar UV and we demonstrate that Fyn is a primary redox sensor involved in SSL-induced signal transduction. Reactive oxygen species (ROS) generated by SSL exposure directly oxidize Cys488 of Fyn, resulting in increased Fyn kinase activity. Fyn oxidation was increased in mouse skin after SSL exposure and Fyn-knockout mice formed larger and more tumors compared with Fyn wild-type mice when exposed to SSL for an extended period of time. Murine embryonic fibroblasts (MEFs) lacking Fyn and cells in which Fyn expression was knocked down were resistant to SSL-induced apoptosis. Furthermore, cells expressing mutant Fyn (C448A) were resistant to SSL-induced apoptosis. These findings suggest that Fyn acts as a regulatory nexus between solar UV, ROS and signal transduction during skin carcinogenesis.

  6. Octadecanoid-Mediated Signal Transduction in Higher Plants

    NASA Astrophysics Data System (ADS)

    Weiler, Elmar W.

    The observation that methyljasmonate is a strong promoter of senescence marked the discovery of lipid-derived signaling molecules of higher plants. This group of compounds, now collectively termed octadecanoids, is derived from the fatty acid α-linolenic acid and involved in physiological processes such diverse as the triggering of defense reactions against herbivores and pathogens, mechanotransduction, plant volatile emission, potato tuberization, and many others. Recent research has yielded clues to a deeper understanding of octadecanoid biology. Control over this central signaling system may open new avenues in biological pest control through plant defense regulators.

  7. Regulation of Early Steps of GPVI Signal Transduction by Phosphatases: A Systems Biology Approach

    PubMed Central

    Dunster, Joanne L.; Mazet, Francoise; Fry, Michael J.; Gibbins, Jonathan M.; Tindall, Marcus J.

    2015-01-01

    We present a data-driven mathematical model of a key initiating step in platelet activation, a central process in the prevention of bleeding following Injury. In vascular disease, this process is activated inappropriately and causes thrombosis, heart attacks and stroke. The collagen receptor GPVI is the primary trigger for platelet activation at sites of injury. Understanding the complex molecular mechanisms initiated by this receptor is important for development of more effective antithrombotic medicines. In this work we developed a series of nonlinear ordinary differential equation models that are direct representations of biological hypotheses surrounding the initial steps in GPVI-stimulated signal transduction. At each stage model simulations were compared to our own quantitative, high-temporal experimental data that guides further experimental design, data collection and model refinement. Much is known about the linear forward reactions within platelet signalling pathways but knowledge of the roles of putative reverse reactions are poorly understood. An initial model, that includes a simple constitutively active phosphatase, was unable to explain experimental data. Model revisions, incorporating a complex pathway of interactions (and specifically the phosphatase TULA-2), provided a good description of the experimental data both based on observations of phosphorylation in samples from one donor and in those of a wider population. Our model was used to investigate the levels of proteins involved in regulating the pathway and the effect of low GPVI levels that have been associated with disease. Results indicate a clear separation in healthy and GPVI deficient states in respect of the signalling cascade dynamics associated with Syk tyrosine phosphorylation and activation. Our approach reveals the central importance of this negative feedback pathway that results in the temporal regulation of a specific class of protein tyrosine phosphatases in controlling the rate

  8. Use of double-stranded RNA interference in Drosophila cell lines to dissect signal transduction pathways

    PubMed Central

    Clemens, James C.; Worby, Carolyn A.; Simonson-Leff, Nancy; Muda, Marco; Maehama, Tomohiko; Hemmings, Brian A.; Dixon, Jack E.

    2000-01-01

    We demonstrate the efficacy of double-stranded RNA-mediated interference (RNAi) of gene expression in generating “knock-out” phenotypes for specific proteins in several Drosophila cell lines. We prove the applicability of this technique for studying signaling cascades by dissecting the well-characterized insulin signal transduction pathway. Specifically, we demonstrate that inhibiting the expression of the DSOR1 (mitogen-activated protein kinase kinase, MAPKK) prevents the activation of the downstream ERK-A (MAPK). In contrast, blocking ERK-A expression results in increased activation of DSOR1. We also show that Drosophila AKT (DAKT) activation depends on the insulin receptor substrate, CHICO (IRS1–4). Finally, we demonstrate that blocking the expression of Drosophila PTEN results in the activation of DAKT. In all cases, the interference of the biochemical cascade by RNAi is consistent with the known steps in the pathway. We extend this powerful technique to study two proteins, DSH3PX1 and Drosophila ACK (DACK). DSH3PX1 is an SH3, phox homology domain-containing protein, and DACK is homologous to the mammalian activated Cdc42 tyrosine kinase, ACK. Using RNAi, we demonstrate that DACK is upstream of DSH3PX1 phosphorylation, making DSH3PX1 an identified downstream target/substrate of ACK-like tyrosine kinases. These experiments highlight the usefulness of RNAi in dissecting complex biochemical signaling cascades and provide a highly effective method for determining the function of the identified genes arising from the Drosophila genome sequencing project. PMID:10823906

  9. Regulation of Early Steps of GPVI Signal Transduction by Phosphatases: A Systems Biology Approach.

    PubMed

    Dunster, Joanne L; Mazet, Francoise; Fry, Michael J; Gibbins, Jonathan M; Tindall, Marcus J

    2015-11-01

    We present a data-driven mathematical model of a key initiating step in platelet activation, a central process in the prevention of bleeding following Injury. In vascular disease, this process is activated inappropriately and causes thrombosis, heart attacks and stroke. The collagen receptor GPVI is the primary trigger for platelet activation at sites of injury. Understanding the complex molecular mechanisms initiated by this receptor is important for development of more effective antithrombotic medicines. In this work we developed a series of nonlinear ordinary differential equation models that are direct representations of biological hypotheses surrounding the initial steps in GPVI-stimulated signal transduction. At each stage model simulations were compared to our own quantitative, high-temporal experimental data that guides further experimental design, data collection and model refinement. Much is known about the linear forward reactions within platelet signalling pathways but knowledge of the roles of putative reverse reactions are poorly understood. An initial model, that includes a simple constitutively active phosphatase, was unable to explain experimental data. Model revisions, incorporating a complex pathway of interactions (and specifically the phosphatase TULA-2), provided a good description of the experimental data both based on observations of phosphorylation in samples from one donor and in those of a wider population. Our model was used to investigate the levels of proteins involved in regulating the pathway and the effect of low GPVI levels that have been associated with disease. Results indicate a clear separation in healthy and GPVI deficient states in respect of the signalling cascade dynamics associated with Syk tyrosine phosphorylation and activation. Our approach reveals the central importance of this negative feedback pathway that results in the temporal regulation of a specific class of protein tyrosine phosphatases in controlling the rate

  10. The carboxyl terminal tyrosine 417 residue of NOK has an autoinhibitory effect on NOK-mediated signaling transductions

    SciTech Connect

    Li Yinghua; Zhong Shan; Rong Zhili; Ren Yongming; Li Zhiyong; Zhang Shuping; Chang Zhijie; Liu Li . E-mail: Liu_Li@mail.tsinghua.edu.cn

    2007-05-04

    Receptor protein tyrosine kinases (RPTKs) are essential mediators of cell growth, differentiation, migration, and metabolism. Recently, a novel RPTK named NOK has been cloned and characterized. In current study, we investigated the role of the carboxyl terminal tyrosine 417 residue of NOK in the activations of different signaling pathways. A single tyrosine to phenylalanine point mutation at Y417 site (Y417 F) not only dramatically enhanced the NOK-induced activation of extracellular signal-regulated kinase (ERK), but also markedly promoted the NOK-mediated activation of both signal transducer and activator of transcription 1 and 3 (STAT1 and 3). Moreover, the proliferation potential of NIH3T3-NOK (Y417F) stable cells were significantly elevated as compared with that of NIH3T3-NOK. Overall, our results demonstrate that the tyrosine Y417 residue at the carboxyl tail of NOK exhibits an autoinhibitory role in NOK-mediated signaling transductions.

  11. Dynamic signaling in the Hog1 MAPK pathway relies on high basal signal transduction.

    PubMed

    Macia, Javier; Regot, Sergi; Peeters, Tom; Conde, Núria; Solé, Ricard; Posas, Francesc

    2009-01-01

    Appropriate regulation of the Hog1 mitogen-activated protein kinase (MAPK) pathway is essential for cells to survive osmotic stress. Here, we show that the two sensing mechanisms upstream of Hog1 display different signaling properties. The Sho1 branch is an inducible nonbasal system, whereas the Sln1 branch shows high basal signaling that is restricted by a MAPK-mediated feedback mechanism. A two-dimensional mathematical model of the Snl1 branch, including high basal signaling and a Hog1-regulated negative feedback, shows that a system with basal signaling exhibits higher efficiency, with faster response times and higher sensitivity to variations in external signals, than would systems without basal signaling. Analysis of two other yeast MAPK pathways, the Fus3 and Kss1 signaling pathways, indicates that high intrinsic basal signaling may be a general property of MAPK pathways allowing rapid and sensitive responses to environmental changes. PMID:19318625

  12. Signal transduction by VEGF receptors in regulation of angiogenesis and lymphangiogenesis

    SciTech Connect

    Shibuya, Masabumi . E-mail: shibuya@ims.u-tokyo.ac.jp; Claesson-Welsh, Lena . E-mail: lena.welsh@genpat.uu.se

    2006-03-10

    The VEGF/VPF (vascular endothelial growth factor/vascular permeability factor) ligands and receptors are crucial regulators of vasculogenesis, angiogenesis, lymphangiogenesis and vascular permeability in vertebrates. VEGF-A, the prototype VEGF ligand, binds and activates two tyrosine kinase receptors: VEGFR1 (Flt-1) and VEGFR2 (KDR/Flk-1). VEGFR1, which occurs in transmembrane and soluble forms, negatively regulates vasculogenesis and angiogenesis during early embryogenesis, but it also acts as a positive regulator of angiogenesis and inflammatory responses, playing a role in several human diseases such as rheumatoid arthritis and cancer. The soluble VEGFR1 is overexpressed in placenta in preeclampsia patients. VEGFR2 has critical functions in physiological and pathological angiogenesis through distinct signal transduction pathways regulating proliferation and migration of endothelial cells. VEGFR3, a receptor for the lymphatic growth factors VEGF-C and VEGF-D, but not for VEGF-A, regulates vascular and lymphatic endothelial cell function during embryogenesis. Loss-of-function variants of VEGFR3 have been identified in lymphedema. Formation of tumor lymphatics may be stimulated by tumor-produced VEGF-C, allowing increased spread of tumor metastases through the lymphatics. Mapping the signaling system of these important receptors may provide the knowledge necessary to suppress specific signaling pathways in major human diseases.

  13. Dynamics and stability of a three-dimensional model of cell signal transduction with delay

    NASA Astrophysics Data System (ADS)

    Levy, Chris; Iron, David

    2015-07-01

    In this paper, we consider a three-dimensional model of cell signal transduction with delay. The deactivation of signalling proteins occurs throughout the cytosol and activation is localized to specific sites in the cell. The enzyme kinetic functions employ a constant delay to model the time lapse during reactions and also the recovery times associated with conformational changes. We use matched asymptotic expansions to construct the dynamic solutions of signalling protein concentrations. The result of the asymptotic analysis is a system of delayed differential algebraic equations. This reduced system is compared to numerical simulations of the full three-dimensional system. As well, we consider the stability of equilibrium solutions. We find that the systems under consideration may undergo Hopf bifurcations for certain delay values. In these cases sustained oscillations are observed. The Poincaré-Lindstedt3 method is used to improve upon the asymptotic approximations. The simulations of the full three-dimensional system correspond well with simulations of the reduced delayed differential algebraic equations.

  14. The cytoplasmic and the transmembrane domains are not sufficient for class I MHC signal transduction.

    PubMed

    Gur, H; Geppert, T D; Wacholtz, M C; Lipsky, P E

    1999-02-01

    Class I MHC molecules deliver activation signals to T cells. To analyze the role of the cytoplasmic and the transmembrane (TM) domains of class I MHC molecules in T cell activation, Jurkat cells were transfected with genes for truncated class I MHC molecules which had only four intracytoplasmic amino acids and no potential phosphorylation sites or native molecules or both. Cross-linking either the native or the truncated molecules induced IL-2 production even under limiting stimulation conditions of low engagement of the stimulating mAb. Moreover, direct comparison of transfected truncated and native class I MHC molecules expressed on the same cell revealed significant stimulation induced by cross-linking the truncated molecules, despite low expression. In addition, truncated class I MHC molecules were as able to synergize with CD3, CD2, or CD28 initiated IL-2 production as native molecules. In further experiments, hybrid constructs made of the extracellular portion of the murine CD8 alpha chain and of the TM and the intracytoplasmic domains of H-2Kk class I MHC molecule were transfected into Jurkat T cells. The expression of the transfected hybrid molecules was comparable to that of the native HLA-B7 molecules. Cross-linking the intact monomorphic HLA-A,B,C epitope or the polymorphic HLA-B7 epitope induced IL-2 production upon costimulation with PMA. In contrast, cross-linking the hybrid molecules generated neither an increase in intracellular calcium concentration ([Ca2+]i) nor stimulated IL-2 production. By contrast, cross-linking intact murine class I MHC molecules induced [Ca2+]i, signal and IL-2 production in transfected Jurkat cells. The data therefore indicate that unlike many other signaling molecules, signaling via class I MHC molecules does not involve the cytoplasmic and the TM portions of the molecule, but rather class I MHC signal transduction is likely to be mediated by the extracellular domain of the molecule.

  15. Signal transduction regulating meristem development in Arabidopsis. Final report

    SciTech Connect

    Cark, Steven E.

    2003-09-10

    Research support by DE-FG02-96ER20227 focused on the CLV loci and their regulation of organ formation at the Arabidopsis shoot meristem. Shoot meristem function is central to plant development as all of the above-ground organs and tissues of the plant are derived post-embryonically from the shoot meristem. At the shoot meristem, stem cells are maintained, and progeny cells undergo a switch toward differentiation and organ formation. The CLV loci, represented by three genes CLV1, CLV2 and CLV3 are key regulators of meristem development. Each of the CLV loci encode a putative receptor-mediated signaling component. When this work began, virtually nothing was known about receptor-mediated signaling in plants. Thus, our goal was to both characterize these genes and the proteins they encode as regulators of meristem development, and to investigate how receptor-mediated signaling might function in plants. Our work lead to several major publications that were significant contributions to understanding this system.

  16. Signal transduction in light–oxygen–voltage receptors lacking the adduct-forming cysteine residue

    PubMed Central

    Yee, Estella F.; Diensthuber, Ralph P.; Vaidya, Anand T.; Borbat, Peter P.; Engelhard, Christopher; Freed, Jack H.; Bittl, Robert; Möglich, Andreas; Crane, Brian R.

    2015-01-01

    Light–oxygen–voltage (LOV) receptors sense blue light through the photochemical generation of a covalent adduct between a flavin-nucleotide chromophore and a strictly conserved cysteine residue. Here we show that, after cysteine removal, the circadian-clock LOV-protein Vivid still undergoes light-induced dimerization and signalling because of flavin photoreduction to the neutral semiquinone (NSQ). Similarly, photoreduction of the engineered LOV histidine kinase YF1 to the NSQ modulates activity and downstream effects on gene expression. Signal transduction in both proteins hence hinges on flavin protonation, which is common to both the cysteinyl adduct and the NSQ. This general mechanism is also conserved by natural cysteine-less, LOV-like regulators that respond to chemical or photoreduction of their flavin cofactors. As LOV proteins can react to light even when devoid of the adduct-forming cysteine, modern LOV photoreceptors may have arisen from ancestral redox-active flavoproteins. The ability to tune LOV reactivity through photoreduction may have important implications for LOV mechanism and optogenetic applications. PMID:26648256

  17. Signal transduction in light-oxygen-voltage receptors lacking the adduct-forming cysteine residue.

    PubMed

    Yee, Estella F; Diensthuber, Ralph P; Vaidya, Anand T; Borbat, Peter P; Engelhard, Christopher; Freed, Jack H; Bittl, Robert; Möglich, Andreas; Crane, Brian R

    2015-12-09

    Light-oxygen-voltage (LOV) receptors sense blue light through the photochemical generation of a covalent adduct between a flavin-nucleotide chromophore and a strictly conserved cysteine residue. Here we show that, after cysteine removal, the circadian-clock LOV-protein Vivid still undergoes light-induced dimerization and signalling because of flavin photoreduction to the neutral semiquinone (NSQ). Similarly, photoreduction of the engineered LOV histidine kinase YF1 to the NSQ modulates activity and downstream effects on gene expression. Signal transduction in both proteins hence hinges on flavin protonation, which is common to both the cysteinyl adduct and the NSQ. This general mechanism is also conserved by natural cysteine-less, LOV-like regulators that respond to chemical or photoreduction of their flavin cofactors. As LOV proteins can react to light even when devoid of the adduct-forming cysteine, modern LOV photoreceptors may have arisen from ancestral redox-active flavoproteins. The ability to tune LOV reactivity through photoreduction may have important implications for LOV mechanism and optogenetic applications.

  18. Succinate, an intermediate in metabolism, signal transduction, ROS, hypoxia, and tumorigenesis.

    PubMed

    Tretter, Laszlo; Patocs, Attila; Chinopoulos, Christos

    2016-08-01

    Succinate is an important metabolite at the cross-road of several metabolic pathways, also involved in the formation and elimination of reactive oxygen species. However, it is becoming increasingly apparent that its realm extends to epigenetics, tumorigenesis, signal transduction, endo- and paracrine modulation and inflammation. Here we review the pathways encompassing succinate as a metabolite or a signal and how these may interact in normal and pathological conditions.(1).

  19. Succinate, an intermediate in metabolism, signal transduction, ROS, hypoxia, and tumorigenesis.

    PubMed

    Tretter, Laszlo; Patocs, Attila; Chinopoulos, Christos

    2016-08-01

    Succinate is an important metabolite at the cross-road of several metabolic pathways, also involved in the formation and elimination of reactive oxygen species. However, it is becoming increasingly apparent that its realm extends to epigenetics, tumorigenesis, signal transduction, endo- and paracrine modulation and inflammation. Here we review the pathways encompassing succinate as a metabolite or a signal and how these may interact in normal and pathological conditions.(1). PMID:26971832

  20. Combinations of SNPs Related to Signal Transduction in Bipolar Disorder

    PubMed Central

    Koefoed, Pernille; Andreassen, Ole A.; Bennike, Bente; Dam, Henrik; Djurovic, Srdjan; Hansen, Thomas; Jorgensen, Martin Balslev; Kessing, Lars Vedel; Melle, Ingrid; Møller, Gert Lykke; Mors, Ole; Werge, Thomas; Mellerup, Erling

    2011-01-01

    Any given single nucleotide polymorphism (SNP) in a genome may have little or no functional impact. A biologically significant effect may possibly emerge only when a number of key SNP-related genotypes occur together in a single organism. Thus, in analysis of many SNPs in association studies of complex diseases, it may be useful to look at combinations of genotypes. Genes related to signal transmission, e.g., ion channel genes, may be of interest in this respect in the context of bipolar disorder. In the present study, we analysed 803 SNPs in 55 genes related to aspects of signal transmission and calculated all combinations of three genotypes from the 3×803 SNP genotypes for 1355 controls and 607 patients with bipolar disorder. Four clusters of patient-specific combinations were identified. Permutation tests indicated that some of these combinations might be related to bipolar disorder. The WTCCC bipolar dataset were use for replication, 469 of the 803 SNP were present in the WTCCC dataset either directly (n = 132) or by imputation (n = 337) covering 51 of our selected genes. We found three clusters of patient-specific 3×SNP combinations in the WTCCC dataset. Different SNPs were involved in the clusters in the two datasets. The present analyses of the combinations of SNP genotypes support a role for both genetic heterogeneity and interactions in the genetic architecture of bipolar disorder. PMID:21897858

  1. Gastrointestinal Congestion Dilates the Hepatic Artery Through the P38 MAPK Signal Transduction Pathway During Liver Transplantation.

    PubMed

    Cao, Zhongping; Tang, Xiaowen; Hou, Shike

    2016-01-01

    During the neohepatic stage of liver transplantation, hemodynamics change markedly. The current study aimed to investigate whether gastrointestinal congestion caused by inferior vena cava and hepatic portal vein clamping can dilate the hepatic artery and to determine the associated mechanisms. Ring segments of the hepatic artery were treated with the plasma from gastrointestinal congestion or the superior vena cava. The fractions in gastrointestinal congestion and the superior vena cava plasma were tested, and the effect of these fractions on the tone of the hepatic artery ring was examined. Different signal transduction blockers and different inhibitors were then used to determine the exact signal transduction pathway involved. In addition, endothelial cell structure was observed by transmission electron microscopy after treatment with the gastrointestinal congestion plasma or the superior vena cava plasma. Gastrointestinal congestion plasma contained more inflammatory cytokines than superior vena cava plasma, and these cytokines could cause hepatic artery ring dilatation. A P38 mitogen-activated protein kinase (P38 MAPK) signal transduction pathway blocker and nitric oxide (NO), prostaglandin (PGI2), nuclear factor-κB (NF-κB), and adenosine triphosphate (ATP)-sensitive K (KATP) channel inhibitors were able to significantly reverse the ring tension caused by gastrointestinal congestion plasma. The normal endothelium was also injured by treatment with gastrointestinal congestion plasma. The inflammatory cytokines in gastrointestinal congestion can cause hepatic artery ring dilatation through the P38 MAPK signal transduction pathway, and this phenomenon is also associated with NO, PGI2, NF-κB, and the KATP channel. These inflammatory cytokines can injure endothelial cells in the hepatic artery. PMID:26955003

  2. Ganglioside Structure Dictates Signal Transduction by Cholera Toxin and Association with Caveolae-like Membrane Domains in Polarized Epithelia

    PubMed Central

    Wolf, Anne A.; Jobling, Michael G.; Wimer-Mackin, Susan; Ferguson-Maltzman, Margaret; Madara, James L.; Holmes, Randall K.; Lencer, Wayne I.

    1998-01-01

    In polarized cells, signal transduction by cholera toxin (CT) requires apical endocytosis and retrograde transport into Golgi cisternae and perhaps ER (Lencer, W.I., C. Constable, S. Moe, M. Jobling, H.M. Webb, S. Ruston, J.L. Madara, T. Hirst, and R. Holmes. 1995. J. Cell Biol. 131:951–962). In this study, we tested whether CT's apical membrane receptor ganglioside GM1 acts specifically in toxin action. To do so, we used CT and the related Escherichia coli heat-labile type II enterotoxin LTIIb. CT and LTIIb distinguish between gangliosides GM1 and GD1a at the cell surface by virtue of their dissimilar receptor-binding B subunits. The enzymatically active A subunits, however, are homologous. While both toxins bound specifically to human intestinal T84 cells (Kd ≈ 5 nM), only CT elicited a cAMP-dependent Cl− secretory response. LTIIb, however, was more potent than CT in eliciting a cAMP-dependent response from mouse Y1 adrenal cells (toxic dose 10 vs. 300 pg/well). In T84 cells, CT fractionated with caveolae-like detergent-insoluble membranes, but LTIIb did not. To investigate further the relationship between the specificity of ganglioside binding and partitioning into detergent-insoluble membranes and signal transduction, CT and LTIIb chimeric toxins were prepared. Analysis of these chimeric toxins confirmed that toxin-induced signal transduction depended critically on the specificity of ganglioside structure. The mechanism(s) by which ganglioside GM1 functions in signal transduction likely depends on coupling CT with caveolae or caveolae-related membrane domains. PMID:9585411

  3. Mitogenic signal transduction in T lymphocytes in microgravity

    NASA Technical Reports Server (NTRS)

    Cogoli, A.; Bechler, B.; Cogoli-Greuter, M.; Criswell, S. B.; Joller, H.; Joller, P.; Hunzinger, E.; Muller, O.

    1993-01-01

    The activation by concanavalin A Con A of human peripheral blood lymphocytes (PBLs) in the presence of monocytes as accessory cells was investigated in cultures exposed to microgravity conditions in Spacelab. Activation of T cells was measured as incorporation of [3H]thymidine into DNA, secretion of interleukin-2 (IL-2), and interferon-gamma, and expression of IL-2 receptors. Whereas, as discovered in earlier experiments, the activation of resuspended T cells is strongly inhibited, activation of cells attached to microcarrier beads is more than doubled in microgravity. The results suggest that the depression of the activation in resuspended cells may be attributed to a malfunction of monocytes acting as accessory cells. In fact, although the ultrastructure of resuspended monocytes is not altered in microgravity, the secretion of IL-1 is strongly inhibited. Our data suggest that (1) IL-2 is produced independently of IL-1, (2) IL-1 production is triggered only when monocytes (and lymphocytes?) adhere to microcarriers, (3) the expression of IL-2 receptors depends on IL-1, and (4) provided sufficient IL-1 is available, activation is enhanced in microgravity. Finally, cultures of resuspended PBLs and monocytes in microgravity constitute a complete and natural system in which monocytes are not operational. This may be useful for studies of the role of accessory cells and cell-cell interactions in T lymphocyte activation.

  4. Backbone NMR reveals allosteric signal transduction networks in the β1-adrenergic receptor.

    PubMed

    Isogai, Shin; Deupi, Xavier; Opitz, Christian; Heydenreich, Franziska M; Tsai, Ching-Ju; Brueckner, Florian; Schertler, Gebhard F X; Veprintsev, Dmitry B; Grzesiek, Stephan

    2016-02-11

    G protein-coupled receptors (GPCRs) are physiologically important transmembrane signalling proteins that trigger intracellular responses upon binding of extracellular ligands. Despite recent breakthroughs in GPCR crystallography, the details of ligand-induced signal transduction are not well understood owing to missing dynamical information. In principle, such information can be provided by NMR, but so far only limited data of functional relevance on few side-chain sites of eukaryotic GPCRs have been obtained. Here we show that receptor motions can be followed at virtually any backbone site in a thermostabilized mutant of the turkey β1-adrenergic receptor (β1AR). Labelling with [(15)N]valine in a eukaryotic expression system provides over twenty resolved resonances that report on structure and dynamics in six ligand complexes and the apo form. The response to the various ligands is heterogeneous in the vicinity of the binding pocket, but gets transformed into a homogeneous readout at the intracellular side of helix 5 (TM5), which correlates linearly with ligand efficacy for the G protein pathway. The effect of several pertinent, thermostabilizing point mutations was assessed by reverting them to the native sequence. Whereas the response to ligands remains largely unchanged, binding of the G protein mimetic nanobody NB80 and G protein activation are only observed when two conserved tyrosines (Y227 and Y343) are restored. Binding of NB80 leads to very strong spectral changes throughout the receptor, including the extracellular ligand entrance pocket. This indicates that even the fully thermostabilized receptor undergoes activating motions in TM5, but that the fully active state is only reached in presence of Y227 and Y343 by stabilization with a G protein-like partner. The combined analysis of chemical shift changes from the point mutations and ligand responses identifies crucial connections in the allosteric activation pathway, and presents a general experimental

  5. Prolonged hyperinsulinemia affects metabolic signal transduction markers in a tissue specific manner.

    PubMed

    Campolo, A; de Laat, M A; Keith, L; Gruntmeir, K J; Lacombe, V A

    2016-04-01

    Insulin dysregulation is common in horses although the mechanisms of metabolic dysfunction are poorly understood. We hypothesized that insulin signaling in striated (cardiac and skeletal) muscle and lamellae may be mediated through different receptors as a result of receptor content, and that transcriptional regulation of downstream signal transduction and glucose transport may also differ between tissues sites during hyperinsulinemia. Archived samples from horses treated with a prolonged insulin infusion or a balanced electrolyte solution were used. All treated horses developed marked hyperinsulinemia and clinical laminitis. Protein expression was compared across tissues for the insulin receptor and insulin-like growth factor 1 receptor (IGF-1R) by immunoblotting. Gene expression of metabolic insulin-signaling markers (insulin receptor substrate 1, Akt2, and glycogen synthase kinase 3 beta [GSK-3β]) and glucose transport (basal glucose transporter 1 and insulin-sensitive glucose transporter 4) was evaluated using real-time reverse transcription polymerase chain reaction. Lamellar tissue contained significantly more IGF-1R protein than skeletal muscle, indicating the potential significance of IGF-1R signaling for this tissue. Gene expression of the selected markers of insulin signaling and glucose transport in skeletal muscle and lamellar tissues was unaffected by prolonged hyperinsulinemia. In contrast, the significant upregulation of Akt2, GSK-3β, GLUT1, and GLUT4 gene expression in cardiac tissue suggested that the prolonged hyperinsulinemia induced an increase in insulin sensitivity and a transcriptional activation of glucose transport. Responses to insulin are tissue-specific, and extrapolation of data across tissue sites is inappropriate. PMID:26773366

  6. Autophagy signal transduction by ATG proteins: from hierarchies to networks.

    PubMed

    Wesselborg, Sebastian; Stork, Björn

    2015-12-01

    Autophagy represents an intracellular degradation process which is involved in both cellular homeostasis and disease settings. In the last two decades, the molecular machinery governing this process has been characterized in detail. To date, several key factors regulating this intracellular degradation process have been identified. The so-called autophagy-related (ATG) genes and proteins are central to this process. However, several additional molecules contribute to the outcome of an autophagic response. Several review articles describing the molecular process of autophagy have been published in the recent past. In this review article we would like to add the most recent findings to this knowledge, and to give an overview of the network character of the autophagy signaling machinery. PMID:26390974

  7. Emerging principles governing signal transduction by pattern-recognition receptors.

    PubMed

    Kagan, Jonathan C; Barton, Gregory M

    2014-11-13

    The problem of recognizing and disposing of non-self-organisms, whether for nutrients or defense, predates the evolution of multicellularity. Accordingly, the function of the innate immune system is often intimately associated with fundamental aspects of cell biology. Here, we review our current understanding of the links between cell biology and pattern-recognition receptors of the innate immune system. We highlight the importance of receptor localization for the detection of microbes and for the initiation of antimicrobial signaling pathways. We discuss examples that illustrate how pattern-recognition receptors influence, and are influenced by, the general membrane trafficking machinery of mammalian cells. In the future, cell biological analysis likely will rival pure genetic analysis as a tool to uncover fundamental principles that govern host-microbe interactions.

  8. A short form of leptin receptor performs signal transduction.

    PubMed

    Murakami, T; Yamashita, T; Iida, M; Kuwajima, M; Shima, K

    1997-02-01

    The obese (ob) gene product, leptin, a peptide hormone, which is synthesized in adipocytes, is a satiety factor and is involved in the control of body weight via the regulation of energy homeostasis. Several alternate spliced isoforms (a-e, as well as others) of the leptin receptor (OBR) have been cloned, all of which, except for OBRe (soluble form), contain a single transmembrane domain. They share the same extracellular domain, with homology to the class I cytokine receptor family. The OBRb, which has longest cytoplasmic domain, is expressed in high levels in the hypothalamus and is thought to be the only isoform capable of signal transmission. Herein, we report the mRNA expression of immediate early genes, c-fos, c-jun and jun-B, which are induced by leptin addition, not only in CHO cells expressing the OBRb, but also in cells expressing one of the short form receptors, OBRa.

  9. A local difference in Hedgehog signal transduction increases mechanical cell bond tension and biases cell intercalations along the Drosophila anteroposterior compartment boundary.

    PubMed

    Rudolf, Katrin; Umetsu, Daiki; Aliee, Maryam; Sui, Liyuan; Jülicher, Frank; Dahmann, Christian

    2015-11-15

    Tissue organization requires the interplay between biochemical signaling and cellular force generation. The formation of straight boundaries separating cells with different fates into compartments is important for growth and patterning during tissue development. In the developing Drosophila wing disc, maintenance of the straight anteroposterior (AP) compartment boundary involves a local increase in mechanical tension at cell bonds along the boundary. The biochemical signals that regulate mechanical tension along the AP boundary, however, remain unknown. Here, we show that a local difference in Hedgehog signal transduction activity between anterior and posterior cells is necessary and sufficient to increase mechanical tension along the AP boundary. This difference in Hedgehog signal transduction is also required to bias cell rearrangements during cell intercalations to keep the characteristic straight shape of the AP boundary. Moreover, severing cell bonds along the AP boundary does not reduce tension at neighboring bonds, implying that active mechanical tension is upregulated, cell bond by cell bond. Finally, differences in the expression of the homeodomain-containing protein Engrailed also contribute to the straight shape of the AP boundary, independently of Hedgehog signal transduction and without modulating cell bond tension. Our data reveal a novel link between local differences in Hedgehog signal transduction and a local increase in active mechanical tension of cell bonds that biases junctional rearrangements. The large-scale shape of the AP boundary thus emerges from biochemical signals inducing patterns of active tension on cell bonds.

  10. The merged basins of signal transduction pathways in spatiotemporal cell biology.

    PubMed

    Hou, Yingchun; Hou, Yang; He, Siyu; Ma, Caixia; Sun, Mengyao; He, Huimin; Gao, Ning

    2014-03-01

    Numerous evidences have indicated that a signal system is composed by signal pathways, each pathway is composed by sub-pathways, and the sub-pathway is composed by the original signal terminals initiated with a protein/gene. We infer the terminal signals merged signal transduction system as "signal basin". In this article, we discussed the composition and regulation of signal basins, and the relationship between the signal basin control and triple W of spatiotemporal cell biology. Finally, we evaluated the importance of the systemic regulation to gene expression by signal basins under triple W. We hope our discussion will be the beginning to cause the attention for this area from the scientists of life science.

  11. Expansion of Signal Transduction Pathways in Fungi by Extensive Genome Duplication.

    PubMed

    Corrochano, Luis M; Kuo, Alan; Marcet-Houben, Marina; Polaino, Silvia; Salamov, Asaf; Villalobos-Escobedo, José M; Grimwood, Jane; Álvarez, M Isabel; Avalos, Javier; Bauer, Diane; Benito, Ernesto P; Benoit, Isabelle; Burger, Gertraud; Camino, Lola P; Cánovas, David; Cerdá-Olmedo, Enrique; Cheng, Jan-Fang; Domínguez, Angel; Eliáš, Marek; Eslava, Arturo P; Glaser, Fabian; Gutiérrez, Gabriel; Heitman, Joseph; Henrissat, Bernard; Iturriaga, Enrique A; Lang, B Franz; Lavín, José L; Lee, Soo Chan; Li, Wenjun; Lindquist, Erika; López-García, Sergio; Luque, Eva M; Marcos, Ana T; Martin, Joel; McCluskey, Kevin; Medina, Humberto R; Miralles-Durán, Alejandro; Miyazaki, Atsushi; Muñoz-Torres, Elisa; Oguiza, José A; Ohm, Robin A; Olmedo, María; Orejas, Margarita; Ortiz-Castellanos, Lucila; Pisabarro, Antonio G; Rodríguez-Romero, Julio; Ruiz-Herrera, José; Ruiz-Vázquez, Rosa; Sanz, Catalina; Schackwitz, Wendy; Shahriari, Mahdi; Shelest, Ekaterina; Silva-Franco, Fátima; Soanes, Darren; Syed, Khajamohiddin; Tagua, Víctor G; Talbot, Nicholas J; Thon, Michael R; Tice, Hope; de Vries, Ronald P; Wiebenga, Ad; Yadav, Jagjit S; Braun, Edward L; Baker, Scott E; Garre, Victoriano; Schmutz, Jeremy; Horwitz, Benjamin A; Torres-Martínez, Santiago; Idnurm, Alexander; Herrera-Estrella, Alfredo; Gabaldón, Toni; Grigoriev, Igor V

    2016-06-20

    Plants and fungi use light and other signals to regulate development, growth, and metabolism. The fruiting bodies of the fungus Phycomyces blakesleeanus are single cells that react to environmental cues, including light, but the mechanisms are largely unknown [1]. The related fungus Mucor circinelloides is an opportunistic human pathogen that changes its mode of growth upon receipt of signals from the environment to facilitate pathogenesis [2]. Understanding how these organisms respond to environmental cues should provide insights into the mechanisms of sensory perception and signal transduction by a single eukaryotic cell, and their role in pathogenesis. We sequenced the genomes of P. blakesleeanus and M. circinelloides and show that they have been shaped by an extensive genome duplication or, most likely, a whole-genome duplication (WGD), which is rarely observed in fungi [3-6]. We show that the genome duplication has expanded gene families, including those involved in signal transduction, and that duplicated genes have specialized, as evidenced by differences in their regulation by light. The transcriptional response to light varies with the developmental stage and is still observed in a photoreceptor mutant of P. blakesleeanus. A phototropic mutant of P. blakesleeanus with a heterozygous mutation in the photoreceptor gene madA demonstrates that photosensor dosage is important for the magnitude of signal transduction. We conclude that the genome duplication provided the means to improve signal transduction for enhanced perception of environmental signals. Our results will help to understand the role of genome dynamics in the evolution of sensory perception in eukaryotes. PMID:27238284

  12. Expansion of Signal Transduction Pathways in Fungi by Extensive Genome Duplication.

    PubMed

    Corrochano, Luis M; Kuo, Alan; Marcet-Houben, Marina; Polaino, Silvia; Salamov, Asaf; Villalobos-Escobedo, José M; Grimwood, Jane; Álvarez, M Isabel; Avalos, Javier; Bauer, Diane; Benito, Ernesto P; Benoit, Isabelle; Burger, Gertraud; Camino, Lola P; Cánovas, David; Cerdá-Olmedo, Enrique; Cheng, Jan-Fang; Domínguez, Angel; Eliáš, Marek; Eslava, Arturo P; Glaser, Fabian; Gutiérrez, Gabriel; Heitman, Joseph; Henrissat, Bernard; Iturriaga, Enrique A; Lang, B Franz; Lavín, José L; Lee, Soo Chan; Li, Wenjun; Lindquist, Erika; López-García, Sergio; Luque, Eva M; Marcos, Ana T; Martin, Joel; McCluskey, Kevin; Medina, Humberto R; Miralles-Durán, Alejandro; Miyazaki, Atsushi; Muñoz-Torres, Elisa; Oguiza, José A; Ohm, Robin A; Olmedo, María; Orejas, Margarita; Ortiz-Castellanos, Lucila; Pisabarro, Antonio G; Rodríguez-Romero, Julio; Ruiz-Herrera, José; Ruiz-Vázquez, Rosa; Sanz, Catalina; Schackwitz, Wendy; Shahriari, Mahdi; Shelest, Ekaterina; Silva-Franco, Fátima; Soanes, Darren; Syed, Khajamohiddin; Tagua, Víctor G; Talbot, Nicholas J; Thon, Michael R; Tice, Hope; de Vries, Ronald P; Wiebenga, Ad; Yadav, Jagjit S; Braun, Edward L; Baker, Scott E; Garre, Victoriano; Schmutz, Jeremy; Horwitz, Benjamin A; Torres-Martínez, Santiago; Idnurm, Alexander; Herrera-Estrella, Alfredo; Gabaldón, Toni; Grigoriev, Igor V

    2016-06-20

    Plants and fungi use light and other signals to regulate development, growth, and metabolism. The fruiting bodies of the fungus Phycomyces blakesleeanus are single cells that react to environmental cues, including light, but the mechanisms are largely unknown [1]. The related fungus Mucor circinelloides is an opportunistic human pathogen that changes its mode of growth upon receipt of signals from the environment to facilitate pathogenesis [2]. Understanding how these organisms respond to environmental cues should provide insights into the mechanisms of sensory perception and signal transduction by a single eukaryotic cell, and their role in pathogenesis. We sequenced the genomes of P. blakesleeanus and M. circinelloides and show that they have been shaped by an extensive genome duplication or, most likely, a whole-genome duplication (WGD), which is rarely observed in fungi [3-6]. We show that the genome duplication has expanded gene families, including those involved in signal transduction, and that duplicated genes have specialized, as evidenced by differences in their regulation by light. The transcriptional response to light varies with the developmental stage and is still observed in a photoreceptor mutant of P. blakesleeanus. A phototropic mutant of P. blakesleeanus with a heterozygous mutation in the photoreceptor gene madA demonstrates that photosensor dosage is important for the magnitude of signal transduction. We conclude that the genome duplication provided the means to improve signal transduction for enhanced perception of environmental signals. Our results will help to understand the role of genome dynamics in the evolution of sensory perception in eukaryotes.

  13. Hydrogen sulfide in cell signaling, signal transduction, cellular bioenergetics and physiology in C. elegans.

    PubMed

    Módis, Katalin; Wolanska, Katarzyna; Vozdek, Roman

    2013-03-01

    Hydrogen sulfide (H2S), long viewed as a toxic gas and environmental hazard, is emerging as a biological mediator with remarkable physiological and pathophysiological relevance. H2S is now viewed as the third main gasotransmitter in the mammalian body. Its pharmacological characteristic possesses similarities to the other two gasotransmitters - nitric oxide (NO) and carbon monoxide (CO). Many of the biological effects of H2S follow a bell-shaped concentration-response; at low concentration or at lower release rates it has beneficial and cytoprotective effects, while at higher concentrations or fast release rates toxicity becomes apparent. Cellular bioenergetics is a prime example for this bell-shaped dose-response, where H2S, at lower concentrations/rates serves as an inorganic substrate and electron donor for mitochondrial ATP generation, while at high concentration it inhibits mitochondrial respiration by blocking the Complex IV in the mitochondrial electron transport chain. The current review is aimed to focus on the following aspects of H2S biology: 1) a general overview of the general pharmacological characteristics of H2S, 2) a summary of the key H2S-mediated signal transduction pathways, 3) an overview of role of H2S in regulation of cellular bioenergetics, 4) key aspects of H2S physiology in C. elegans (a model system) and, finally 5) the therapeutic potential of H2S donating molecules in various disease states. PMID:23531831

  14. Nanomechanoelectronic signal transduction scheme with metal-oxide-semiconductor field-effect transistor-embedded microcantilevers

    NASA Astrophysics Data System (ADS)

    Tark, Soo-Hyun; Srivastava, Arvind; Chou, Stanley; Shekhawat, Gajendra; Dravid, Vinayak P.

    2009-03-01

    We explore various metal-oxide-semiconductor field-effect transistor (MOSFET)-embedded microcantilever designs to assess their performance as an efficient nanomechanoelectronic signal transduction platform for monitoring deflection in microcantilever-based phenomena such as biochemical sensing and actuation. The current-voltage characteristics of embedded MOSFETs show current noise in the nanoampere range with a large signal-to-noise ratio sufficient to provide measureable output signal. The change in drain current with cantilever deflection is consistent with the effect of stress on carrier mobility and drain current reported in previous studies, validating that the MOSFET cantilevers can directly transduce deflection of a microcantilever into reproducible change in electrical signal.

  15. Control of cancer-related signal transduction networks

    NASA Astrophysics Data System (ADS)

    Albert, Reka

    2013-03-01

    Intra-cellular signaling networks are crucial to the maintenance of cellular homeostasis and for cell behavior (growth, survival, apoptosis, movement). Mutations or alterations in the expression of elements of cellular signaling networks can lead to incorrect behavioral decisions that could result in tumor development and/or the promotion of cell migration and metastasis. Thus, mitigation of the cascading effects of such dysregulations is an important control objective. My group at Penn State is collaborating with wet-bench biologists to develop and validate predictive models of various biological systems. Over the years we found that discrete dynamic modeling is very useful in molding qualitative interaction information into a predictive model. We recently demonstrated the effectiveness of network-based targeted manipulations on mitigating the disease T cell large granular lymphocyte (T-LGL) leukemia. The root of this disease is the abnormal survival of T cells which, after successfully fighting an infection, should undergo programmed cell death. We synthesized the relevant network of within-T-cell interactions from the literature, integrated it with qualitative knowledge of the dysregulated (abnormal) states of several network components, and formulated a Boolean dynamic model. The model indicated that the system possesses a steady state corresponding to the normal cell death state and a T-LGL steady state corresponding to the abnormal survival state. For each node, we evaluated the restorative manipulation consisting of maintaining the node in the state that is the opposite of its T-LGL state, e.g. knocking it out if it is overexpressed in the T-LGL state. We found that such control of any of 15 nodes led to the disappearance of the T-LGL steady state, leaving cell death as the only potential outcome from any initial condition. In four additional cases the probability of reaching the T-LGL state decreased dramatically, thus these nodes are also possible control

  16. New signal transduction paradigms in anthracycline-induced cardiotoxicity.

    PubMed

    Ghigo, Alessandra; Li, Mingchuan; Hirsch, Emilio

    2016-07-01

    Anthracyclines, such as doxorubicin, are the most potent and widely used chemotherapeutic agents for the treatment of a variety of human cancers, including solid tumors and hematological malignancies. However, their clinical use is hampered by severe cardiotoxic side effects and cancer therapy-related heart disease has become a leading cause of morbidity and mortality among cancer survivors. The identification of therapeutic strategies limiting anthracycline cardiotoxicity with preserved antitumor efficacy thus represents the current challenge of cardio-oncologists. Anthracycline cardiotoxicity has been originally ascribed to the ability of this class of drugs to disrupt iron metabolism and generate excess of reactive oxygen species (ROS). However, small clinical trials with iron chelators and anti-oxidants failed to provide any benefit and suggested that doxorubicin cardiotoxicity is not solely due to redox cycling. New emerging explanations include anthracycline-dependent regulation of major signaling pathways controlling DNA damage response, cardiomyocyte survival, cardiac inflammation, energetic stress and gene expression modulation. This review will summarize recent studies unraveling the complex web of mechanisms of doxorubicin-mediated cardiotoxicity, and identifying new druggable players for the prevention of heart disease in cancer patients. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

  17. Role of relaxation time scale in noisy signal transduction.

    PubMed

    Maity, Alok Kumar; Chaudhury, Pinaki; Banik, Suman K

    2015-01-01

    Intra-cellular fluctuations, mainly triggered by gene expression, are an inevitable phenomenon observed in living cells. It influences generation of phenotypic diversity in genetically identical cells. Such variation of cellular components is beneficial in some contexts but detrimental in others. To quantify the fluctuations in a gene product, we undertake an analytical scheme for studying few naturally abundant linear as well as branched chain network motifs. We solve the Langevin equations associated with each motif under the purview of linear noise approximation and derive the expressions for Fano factor and mutual information in close analytical form. Both quantifiable expressions exclusively depend on the relaxation time (decay rate constant) and steady state population of the network components. We investigate the effect of relaxation time constraints on Fano factor and mutual information to indentify a time scale domain where a network can recognize the fluctuations associated with the input signal more reliably. We also show how input population affects both quantities. We extend our calculation to long chain linear motif and show that with increasing chain length, the Fano factor value increases but the mutual information processing capability decreases. In this type of motif, the intermediate components act as a noise filter that tune up input fluctuations and maintain optimum fluctuations in the output. For branched chain motifs, both quantities vary within a large scale due to their network architecture and facilitate survival of living system in diverse environmental conditions.

  18. Neural signal transduction aided by noise in multisynaptic excitatory and inhibitory pathways with saturation

    NASA Astrophysics Data System (ADS)

    Duan, Fabing; Chapeau-Blondeau, François; Abbott, Derek

    2011-08-01

    We study the stochastic resonance phenomenon in saturating dynamical models of neural signal transduction, at the synaptic stage, wherein the noise in multipathways enhances the processing of neuronal information integrated by excitatory and inhibitory synaptic currents. For an excitatory synaptic pathway, the additive intervention of an inhibitory pathway reduces the stochastic resonance effect. However, as the number of synaptic pathways increases, the signal transduction is greatly improved for parallel multipathways that feature both excitation and inhibition. The obtained results lead us to the realization that the collective property of inhibitory synapses assists neural signal transmission, and a parallel array of neurons can enhance their responses to multiple synaptic currents by adjusting the contributions of excitatory and inhibitory currents.

  19. Apoptotic effects of signal transduction inhibitors on human tumor cells with different PTEN expression.

    PubMed

    Pfeiler, Georg; Horn, Felicitas; Lattrich, Claus; Klappenberger, Stefanie; Ortmann, Olaf; Treeck, Oliver

    2007-11-01

    An important mechanism of antitumoral targeted therapies is the induction of apoptosis in tumor cells. Tamoxifen and trastuzumab (Herceptin), respectively, are able to trigger apoptosis in human breast cancer cells. But, frequently altered apoptotic signal cascades, for instance through PTEN mutations, help tumor cells to escape antitumoral therapy. We studied to what extent the apoptotic effect of signal-transduction inhibitors is dependent on PTEN expression. PTEN expression was analysed by Western blot analysis in tumor cell lines of the breast (BT-474, MCF-7, MDA-MB-231), ovary (BG-1, SK-OV-3) and endometrium (Ishikawa, HEC-1A). Apoptotic effects of tamoxifen, trastuzumab, ZD1839 (Iressa) and different mitogen-activated protein kinase (MAP) inhibitors were measured after 24 h of treatment. Cellular apoptosis was determined by the detection of cytoplasmic histone-DNA complexes. The tested tumor cell lines exhibited a different PTEN expression, ranging from a high expression (ovarian cancer cell line BG-1 and BT-474 breast cancer cells) to a total absence of PTEN expression (endometrial Ishikawa cells). The apoptotic effect of receptor-targeting drugs (tamoxifen, trastuzumab, ZD1839) was dependent both on receptor expression and PTEN expression. When cells were treated with MAPK inhibitors, no correlation between PTEN expression and the apoptosis rate was observed. Our data underline the importance of PTEN expression regarding the induction of apoptosis through various targeted therapies.

  20. Hedgehog signaling from the primary cilium to the nucleus: an emerging picture of ciliary localization, trafficking and transduction

    PubMed Central

    Nozawa, Yoko Inès; Lin, Chuwen; Chuang, Pao-Tien

    2013-01-01

    The unexpected connection between cilia and signaling is one of the most exciting developments in cell biology in the past decade. In particular, the Hedgehog (Hh) signaling pathway relies on the primary cilium to regulate tissue patterning and homeostasis in vertebrates. A central question is how ciliary localization and trafficking of Hh pathway components lead to pathway activation and regulation. In this review, we discuss recent studies that reveal the roles of ciliary regulators, components and structures in controlling the movement and signaling of Hh players. These findings significantly increase our mechanistic understanding of how the primary cilium facilitates Hh signal transduction and form the basis for further investigations to define the function of cilia in other signaling processes. PMID:23725801

  1. Modulators of Stomatal Lineage Signal Transduction Alter Membrane Contact Sites and Reveal Specialization among ERECTA Kinases.

    PubMed

    Ho, Chin-Min Kimmy; Paciorek, Tomasz; Abrash, Emily; Bergmann, Dominique C

    2016-08-22

    Signal transduction from a cell's surface to its interior requires dedicated signaling elements and a cellular environment conducive to signal propagation. Plant development, defense, and homeostasis rely on plasma membrane receptor-like kinases to perceive endogenous and environmental signals, but little is known about their immediate downstream targets and signaling modifiers. Using genetics, biochemistry, and live-cell imaging, we show that the VAP-RELATED SUPPRESSOR OF TMM (VST) family is required for ERECTA-mediated signaling in growth and cell-fate determination and reveal a role for ERECTA-LIKE2 in modulating signaling by its sister kinases. We show that VSTs are peripheral plasma membrane proteins that can form complexes with integral ER-membrane proteins, thereby potentially influencing the organization of the membrane milieu to promote efficient and differential signaling from the ERECTA-family members to their downstream intracellular targets.

  2. Signal transduction pathways mediating parathyroid hormone regulation of osteoblastic gene expression

    NASA Technical Reports Server (NTRS)

    Partridge, N. C.; Bloch, S. R.; Pearman, A. T.

    1994-01-01

    Parathyroid hormone (PTH) plays a central role in regulation of calcium metabolism. For example, excessive or inappropriate production of PTH or the related hormone, parathyroid hormone related protein (PTHrP), accounts for the majority of the causes of hypercalcemia. Both hormones act through the same receptor on the osteoblast to elicit enhanced bone resorption by the osteoclast. Thus, the osteoblast mediates the effect of PTH in the resorption process. In this process, PTH causes a change in the function and phenotype of the osteoblast from a cell involved in bone formation to one directing the process of bone resorption. In response to PTH, the osteoblast decreases collagen, alkaline phosphatase, and osteopontin expression and increases production of osteocalcin, cytokines, and neutral proteases. Many of these changes have been shown to be due to effects on mRNA abundance through either transcriptional or post-transcriptional mechanisms. However, the signal transduction pathway for the hormone to cause these changes is not completely elucidated in any case. Binding of PTH and PTHrP to their common receptor has been shown to result in activation of protein kinases A and C and increases in intracellular calcium. The latter has not been implicated in any changes in mRNA of osteoblastic genes. On the other hand activation of PKA can mimic all the effects of PTH; protein kinase C may be involved in some responses. We will discuss possible mechanisms linking PKA and PKC activation to changes in gene expression, particularly at the nuclear level.

  3. The condensed chromatin fiber: an allosteric chemo-mechanical machine for signal transduction and genome processing

    NASA Astrophysics Data System (ADS)

    Lesne, Annick; Bécavin, Christophe; Victor, Jean–Marc

    2012-02-01

    Allostery is a key concept of molecular biology which refers to the control of an enzyme activity by an effector molecule binding the enzyme at another site rather than the active site (allos = other in Greek). We revisit here allostery in the context of chromatin and argue that allosteric principles underlie and explain the functional architecture required for spacetime coordination of gene expression at all scales from DNA to the whole chromosome. We further suggest that this functional architecture is provided by the chromatin fiber itself. The structural, mechanical and topological features of the chromatin fiber endow chromosomes with a tunable signal transduction from specific (or nonspecific) effectors to specific (or nonspecific) active sites. Mechanical constraints can travel along the fiber all the better since the fiber is more compact and regular, which speaks in favor of the actual existence of the (so-called 30 nm) chromatin fiber. Chromatin fiber allostery reconciles both the physical and biochemical approaches of chromatin. We illustrate this view with two supporting specific examples. Moreover, from a methodological point of view, we suggest that the notion of chromatin fiber allostery is particularly relevant for systemic approaches. Finally we discuss the evolutionary power of allostery in the context of chromatin and its relation to modularity.

  4. Driving Cellular Plasticity and Survival Through the Signal Transduction Pathways of Metabotropic Glutamate Receptors

    PubMed Central

    Maiese, Kenneth; Chong, Zhao Zhong; Li, Faqi

    2008-01-01

    Metabotropic glutamate receptors (mGluRs) share a common molecular morphology with other G protein–linked receptors, but there expression throughout the mammalian nervous system places these receptors as essential mediators not only for the initial development of an organism, but also for the vital determination of a cell’s fate during many disorders in the nervous system that include amyotrophic lateral sclerosis, Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, Multiple Sclerosis, epilepsy, trauma, and stroke. Given the ubiquitous distribution of these receptors, the mGluR system impacts upon neuronal, vascular, and glial cell function and is activated by a wide variety of stimuli that includes neurotransmitters, peptides, hormones, growth factors, ions, lipids, and light. Employing signal transduction pathways that can modulate both excitatory and inhibitory responses, the mGluR system drives a spectrum of cellular pathways that involve protein kinases, endonucleases, cellular acidity, energy metabolism, mitochondrial membrane potential, caspases, and specific mitogen-activated protein kinases. Ultimately these pathways can converge to regulate genomic DNA degradation, membrane phosphatidylserine (PS) residue exposure, and inflammatory microglial activation. As we continue to push the envelope for our understanding of this complex and critical family of metabotropic receptors, we should be able to reap enormous benefits for both clinical disease as well as our understanding of basic biology in the nervous system. PMID:16375723

  5. Mechanical Signal Transduction in Countermeasures to Muscle Atrophy

    NASA Technical Reports Server (NTRS)

    Tidball, James G.; Chu, Amy (Technical Monitor)

    2002-01-01

    We have shown that modifications in muscle use result in changes in the expression and activity of calpains and nitric oxide synthase (NOS). Although muscle unloading for 10 days produced no change in the concentrations of calpain 1 or 2 and no change in calpain activation, muscle reloading produced a 90% increase in calpain 2 concentration. We developed an in vitro model to test our hypothesis that nitric oxide can inhibit cytoskeletal breakdown in skeletal muscle cells by inhibiting calpain cleavage of talin. Talin was selected because it is a well-characterized calpain substrate and it is codistributed with calpain in muscle cells. We found that intermittant loading during hindlimb suspension that is sufficient to prevent muscle mass loss that occurs during muscle unloading is also sufficient to prevent the decrease in NOS expression that normally occurs during hindlimb unloading. These findings indicate that therapeutics directed toward regulating the calpain/calpastatin system may be beneficial in preventing muscle mass loss in muscle injury, unloading and disease.

  6. Prion Infection of Mouse Brain Reveals Multiple New Upregulated Genes Involved in Neuroinflammation or Signal Transduction

    PubMed Central

    Striebel, James F.; Race, Brent; Phillips, Katie; Chesebro, Bruce

    2014-01-01

    ABSTRACT Gliosis is often a preclinical pathological finding in neurodegenerative diseases, including prion diseases, but the mechanisms facilitating gliosis and neuronal damage in these diseases are not understood. To expand our knowledge of the neuroinflammatory response in prion diseases, we assessed the expression of key genes and proteins involved in the inflammatory response and signal transduction in mouse brain at various times after scrapie infection. In brains of scrapie-infected mice at pre- and postclinical stages, we identified 15 previously unreported differentially expressed genes related to inflammation or activation of the STAT signal transduction pathway. Levels for the majority of differentially expressed genes increased with time postinfection. In quantitative immunoblotting experiments of STAT proteins, STAT1α, phosphorylated-STAT1α (pSTAT1α), and pSTAT3 were increased between 94 and 131 days postinfection (p.i.) in brains of mice infected with strain 22L. Furthermore, a select group of STAT-associated genes was increased preclinically during scrapie infection, suggesting early activation of the STAT signal transduction pathway. Comparison of inflammatory markers between mice infected with scrapie strains 22L and RML indicated that the inflammatory responses and gene expression profiles in the brains were strikingly similar, even though these scrapie strains infect different brain regions. The endogenous interleukin-1 receptor antagonist (IL-1Ra), an inflammatory marker, was newly identified as increasing preclinically in our model and therefore might influence scrapie pathogenesis in vivo. However, in IL-1Ra-deficient or overexpressor transgenic mice inoculated with scrapie, neither loss nor overexpression of IL-1Ra demonstrated any observable effect on gliosis, protease-resistant prion protein (PrPres) formation, disease tempo, pathology, or expression of the inflammatory genes analyzed. IMPORTANCE Prion infection leads to Pr

  7. Mechanisms of signal transduction by ethylene: overlapping and non-overlapping signalling roles in a receptor family

    PubMed Central

    Shakeel, Samina N.; Wang, Xiaomin; Binder, Brad M.; Schaller, G. Eric

    2013-01-01

    The plant hormone ethylene regulates growth and development as well as responses to biotic and abiotic stresses. Over the last few decades, key elements involved in ethylene signal transduction have been identified through genetic approaches, these elements defining a pathway that extends from initial ethylene perception at the endoplasmic reticulum to changes in transcriptional regulation within the nucleus. Here, we present our current understanding of ethylene signal transduction, focusing on recent developments that support a model with overlapping and non-overlapping roles for members of the ethylene receptor family. We consider the evidence supporting this model for sub-functionalization within the receptor family, and then discuss mechanisms by which such a sub-functionalization may occur. To this end, we consider the importance of receptor interactions in modulating their signal output and how such interactions vary in the receptor family. In addition, we consider evidence indicating that ethylene signal output by the receptors involves both phosphorylation-dependent and phosphorylation-independent mechanisms. We conclude with a current model for signalling by the ethylene receptors placed within the overall context of ethylene signal transduction. PMID:23543258

  8. Ubiquitin-Related Roles of β-Arrestins in Endocytic Trafficking and Signal Transduction.

    PubMed

    Jean-Charles, Pierre-Yves; Rajiv, Vishwaesh; Shenoy, Sudha K

    2016-10-01

    The non-visual arrestins, β-arrestin1, and β-arrestin2 were originally identified as proteins that bind to seven-transmembrane receptors (7TMRs, also called G protein-coupled receptors, GPCRs) and block heterotrimeric G protein activation, thus leading to desensitization of transmembrane signaling. However, as subsequent discoveries have continually demonstrated, their functionality is not constrained to desensitization. They are now recognized for their critical roles in mediating intracellular trafficking of 7TMRs, growth factor receptors, ion transporters, ion channels, nuclear receptors, and non-receptor proteins. Additionally, they function as crucial mediators of ubiquitination of 7TMRs as well as other receptors and non-receptor proteins. Recently, emerging studies suggest that a class of proteins with predicted structural features of β-arrestins regulate substrate ubiquitination in yeast and higher mammals, lending support to the idea that the adaptor role of β-arrestins in protein ubiquitination is evolutionarily conserved. β-arrestins also function as scaffolds for kinases and transduce signals from 7TMRs through pathways that do not require G protein activation. Remarkably, the endocytic and scaffolding functions of β-arrestin are intertwined with its ubiquitination status; the dynamic and site specific ubiquitination on β-arrestin plays a critical role in stabilizing β-arrestin-7TMR association and the formation of signalosomes. This review summarizes the current findings on ubiquitin-dependent regulation of 7TMRs as well as β-arrestins and the potential role of reversible ubiquitination as a "biological switch" in signal transduction. J. Cell. Physiol. 231: 2071-2080, 2016. © 2016 Wiley Periodicals, Inc.

  9. Image informatics for studying signal transduction in cells interacting with 3D matrices

    NASA Astrophysics Data System (ADS)

    Tzeranis, Dimitrios S.; Guo, Jin; Chen, Chengpin; Yannas, Ioannis V.; Wei, Xunbin; So, Peter T. C.

    2014-03-01

    Cells sense and respond to chemical stimuli on their environment via signal transduction pathways, complex networks of proteins whose interactions transmit chemical information. This work describes an implementation of image informatics, imaging-based methodologies for studying signal transduction networks. The methodology developed focuses on studying signal transduction networks in cells that interact with 3D matrices. It utilizes shRNA-based knock down of network components, 3D high-content imaging of cells inside the matrix by spectral multi-photon microscopy, and single-cell quantification using features that describe both cell morphology and cell-matrix adhesion pattern. The methodology is applied in a pilot study of TGFβ signaling via the SMAD pathway in fibroblasts cultured inside porous collagen-GAG scaffolds, biomaterials similar to the ones used clinically to induce skin regeneration. Preliminary results suggest that knocking down all rSMAD components affects fibroblast response to TGFβ1 and TGFβ3 isoforms in different ways, and suggest a potential role for SMAD1 and SMAD5 in regulating TGFβ isoform response. These preliminary results need to be verified with proteomic results that can provide solid evidence about the particular role of individual components of the SMAD pathway.

  10. Peroxiredoxins in Regulation of MAPK Signalling Pathways; Sensors and Barriers to Signal Transduction

    PubMed Central

    Latimer, Heather R.; Veal, Elizabeth A.

    2016-01-01

    Peroxiredoxins are highly conserved and abundant peroxidases. Although the thioredoxin peroxidase activity of peroxiredoxin (Prx) is important to maintain low levels of endogenous hydrogen peroxide, Prx have also been shown to promote hydrogen peroxide-mediated signalling. Mitogen activated protein kinase (MAPK) signalling pathways mediate cellular responses to a variety of stimuli, including reactive oxygen species (ROS). Here we review the evidence that Prx can act as both sensors and barriers to the activation of MAPK and discuss the underlying mechanisms involved, focusing in particular on the relationship with thioredoxin. PMID:26813660

  11. [Nobel prize in physiology of medicine for year 2000 for research of signal transduction in the nervous system].

    PubMed

    Gispen, W H

    2000-11-11

    The three Nobel laureates Arvid Carlsson, Paul Greengard and Eric Kandel have made pioneering discoveries concerning slow synaptic transmission between neurons. As common theme, for which the Nobel Prize in Physiology or Medicine for 2000 is given, the Nobel Assembly chose 'signal transduction in the nervous system'. The work of Carlsson led to the discovery of dopamine as transmitter in the brain and opened the way for the development of the levodopa therapy of patients suffering from Parkinson's disease. His later work concentrated on the dopamine hypothesis of schizophrenia and the rationale for the mechanism of action of antipsychotics. Greengard pioneered the field of receptor-mediated phosphorylation and dephosphorylation of brain proteins. He was the first to describe the cyclic-AMP-dependent protein kinase in the brain and the activation of this kinase following dopamine receptor activation. A substrate enriched in cells that bear dopamine receptors is 'dopamine- and cyclic-AMP-regulated phosphoprotein' (DARPP-32). Phosphorylation by the cyclic-AMP-dependent kinase influences its protein phosphatase inhibiting capacity and, as such, DARPP-32 is an important 'feed-forward activator' in the dopamine signal transduction cascade. Kandel received the prize for his contributions to our understanding of the neural substrate of learning and memory. Most of his work was carried out in the sea slug Aplysia in which he was able to relate three psychologically defined forms of learning--habituation, sensitisation, and classical conditioning--to subcellular processes and intercellular signalling. Kandel is known all over the world for his eminent textbook Principles of Neural Science which inspired generations of young neuroscientists. It seems that it is not so much the signal transduction that joins these laureates but their outstanding conceptual approach to, in fact, three different themes of the neurosciences during the second part of the last century.

  12. Signal transduction pathways in FSH regulation of rat Sertoli cell proliferation.

    PubMed

    Riera, María F; Regueira, Mariana; Galardo, María N; Pellizzari, Eliana H; Meroni, Silvina B; Cigorraga, Selva B

    2012-04-15

    The final number of Sertoli cells reached during the proliferative periods determines sperm production capacity in adulthood. It is well known that FSH is the major Sertoli cell mitogen; however, little is known about the signal transduction pathways that regulate the proliferation of Sertoli cells. The hypothesis of this investigation was that FSH regulates proliferation through a PI3K/Akt/mTORC1 pathway, and additionally, AMPK-dependent mechanisms counteract FSH proliferative effects. The present study was performed in 8-day-old rat Sertoli cell cultures. The results presented herein show that FSH, in addition to increasing p-Akt, p-mTOR, and p-p70S6K levels, increases p-PRAS40 levels, probably contributing to improving mTORC1 signaling. Furthermore, the decrease in FSH-stimulated p-Akt, p-mTOR, p-p70S6K, and p-PRAS40 levels in the presence of wortmannin emphasizes the participation of PI3K in FSH signaling. Additionally, the inhibition of FSH-stimulated Sertoli cell proliferation by the effect of wortmannin and rapamycin point to the relevance of the PI3K/Akt/mTORC1 signaling pathway in the mitotic activity of FSH. On the other hand, by activating AMPK, several interesting observations were made. Activation of AMPK produced an increase in Raptor phosphorylation, a decrease in p70S6K phosphorylation, and a decrease in FSH-stimulated Sertoli cell proliferation. The decrease in FSH-stimulated cell proliferation was accompanied by an increased expression of the cyclin-dependent kinase inhibitors (CDKIs) p19INK4d, p21Cip1, and p27Kip1. In summary, it is concluded that FSH regulates Sertoli cell proliferation with the participation of a PI3K/Akt/mTORC1 pathway and that AMPK activation may be involved in the detention of proliferation by, at least in part, a decrease in mTORC1 signaling and an increase in CDKI expression.

  13. Physiological roles of peroxido-vanadium complexes: Leitmotif as their signal transduction pathway.

    PubMed

    Matsugo, Seiichi; Kanamori, Kan; Sugiyama, Hironori; Misu, Hirofumi; Takamura, Toshinari

    2015-06-01

    Evidence exists that supports the various physiological roles of vanadium compounds, although the amount of vanadium in our body is limited. This limited concentration in our body does not attract much attention of the biological chemists, although the fact is present; even in the 19th century, vanadium derivatives were used for the therapeutic reagents. In the middle of the 20th century, the main focus of vanadium chemistry is mainly on the chemical and material fields. After the first discovery of vanadium compounds expressing ATPase activity, oxidovanadium(IV) sulfate was reported to have insulin mimic activity. Additionally, because some vanadium compounds possess cellular toxicity, trials were also carried out to examine the possible use of vanadium compounds as cancer therapeutics. The application of vanadium complexes was extended in recent years especially in the 21st century. In this review, we briefly explain the historical background of vanadium chemistry and also summarize the physiological role of vanadium complexes mainly focusing on the synthesis and physiological role of peroxidovanadium compounds and their interactions with insulin signal transduction pathways.

  14. Protein serine/threonine kinases in signal transduction for secondary metabolism and morphogenesis in Streptomyces.

    PubMed

    Umeyama, T; Lee, P-C; Horinouchi, S

    2002-08-01

    A number of proteins in the Gram-positive bacterial genus Streptomyces are phosphorylated on their serine/threonine and tyrosine residues in response to developmental phases. AfsR is one of these proteins and acts as a transcriptional factor in both the regulation of secondary metabolism in Streptomyces coelicolor A3(2) and morphological differentiation in Streptomyces griseus. In S. coelicolor A3(2), AfsR is phosphorylated on its serine and threonine residues by more than three protein kinases whose kinase activity is enhanced by means of autophosphorylation on their serine and threonine residues. The degree of autophosphorylation of AfsK is regulated by KbpA which, by binding directly to the kinase domain of AfsK, inhibits its autophosphorylation. Phosphorylation of AfsR enhances its DNA-binding activity and causes it to bind the promoter elements, including -35, of afsS, thus resulting in activation of afsS transcription. ATPase activity of AfsR is essential for this transcriptional activation, probably because the energy available from ATP hydrolysis is required for the isomerization of the closed complex between AfsR and RNA polymerase to a transcriptionally competent open complex. afsS, encoding a 63-amino-acid protein, then activates transcription of actII-ORF4, a pathway-specific transcriptional activator in the actinorhodin biosynthetic gene cluster, in an as yet unknown way. Distribution of the afsK- afsR systems in a wide variety of Streptomyces species and the presence of many phosphorylated proteins in a given Streptomyces strain suggest that the signal transduction via not only two-component regulatory systems but also serine/threonine kinases generally regulates secondary metabolism and morphogenesis in this genus.

  15. Plasma membrane poration by opioid neuropeptides: a possible mechanism of pathological signal transduction.

    PubMed

    Maximyuk, O; Khmyz, V; Lindskog, C-J; Vukojević, V; Ivanova, T; Bazov, I; Hauser, K F; Bakalkin, G; Krishtal, O

    2015-01-01

    Neuropeptides induce signal transduction across the plasma membrane by acting through cell-surface receptors. The dynorphins, endogenous ligands for opioid receptors, are an exception; they also produce non-receptor-mediated effects causing pain and neurodegeneration. To understand non-receptor mechanism(s), we examined interactions of dynorphins with plasma membrane. Using fluorescence correlation spectroscopy and patch-clamp electrophysiology, we demonstrate that dynorphins accumulate in the membrane and induce a continuum of transient increases in ionic conductance. This phenomenon is consistent with stochastic formation of giant (~2.7 nm estimated diameter) unstructured non-ion-selective membrane pores. The potency of dynorphins to porate the plasma membrane correlates with their pathogenic effects in cellular and animal models. Membrane poration by dynorphins may represent a mechanism of pathological signal transduction. Persistent neuronal excitation by this mechanism may lead to profound neuropathological alterations, including neurodegeneration and cell death. PMID:25766322

  16. Role of functionality in two-component signal transduction: A stochastic study

    NASA Astrophysics Data System (ADS)

    Maity, Alok Kumar; Bandyopadhyay, Arnab; Chaudhury, Pinaki; Banik, Suman K.

    2014-03-01

    We present a stochastic formalism for signal transduction processes in a bacterial two-component system. Using elementary mass action kinetics, the proposed model takes care of signal transduction in terms of a phosphotransfer mechanism between the cognate partners of a two-component system, viz., the sensor kinase and the response regulator. Based on the difference in functionality of the sensor kinase, the noisy phosphotransfer mechanism has been studied for monofunctional and bifunctional two-component systems using the formalism of the linear noise approximation. Steady-state analysis of both models quantifies different physically realizable quantities, e.g., the variance, the Fano factor (variance/mean), and mutual information. The resultant data reveal that both systems reliably transfer information of extracellular environment under low external stimulus and in a high-kinase-and-phosphatase regime. We extend our analysis further by studying the role of the two-component system in downstream gene regulation.

  17. Subthreshold Dynamics and Its Effect on Signal Transduction in a Neural System

    NASA Astrophysics Data System (ADS)

    Wang, Yuqing; Wang, Z.; Wang, Wei

    1998-10-01

    Subthreshold dynamics and its effect on signal transduction in a neural system are studied by using the Hindmarsh-Rose neuron model. Under a periodic stimulation, as the constant bias of the stimulus increases, the neuron exhibits subthreshold periodic and subthreshold chaotic responses, suprathreshold chaotic firing of spikes, and mode-locked firing. The phase diagram of the system is obtained. The dynamic behavior obtained is in agreement with experiments on the squid giant axon. In particular, the subthreshold periodic oscillatory state is related to a number of experimental results, such as those found in the neurons of the inferior olivary nucleus. More importantly, we also find that subthreshold chaotic responses play a role analogous to the internal deterministic noise, and can enhance weak signal transduction via a mechanism similar to stochastic resonance.

  18. INOH: ontology-based highly structured database of signal transduction pathways

    PubMed Central

    Sakai, Noriko; Nakamura, Hiromi; Fukagawa, Hiroshi; Fukuda, Ken; Takagi, Toshihisa

    2011-01-01

    The Integrating Network Objects with Hierarchies (INOH) database is a highly structured, manually curated database of signal transduction pathways including Mammalia, Xenopus laevis, Drosophila melanogaster, Caenorhabditis elegans and canonical. Since most pathway knowledge resides in scientific articles, the database focuses on curating and encoding textual knowledge into a machine-processable form. We use a hierarchical pathway representation model with a compound graph, and every pathway component in the INOH database is annotated by a set of uniquely developed ontologies. Finally, we developed the Similarity Search using the combination of a compound graph and hierarchical ontologies. The INOH database is to be a good resource for many users who want to analyze a large protein network. INOH ontologies and 73 signal transduction and 29 metabolic pathway diagrams (including over 6155 interactions and 3395 protein entities) are freely available in INOH XML and BioPAX formats. Database URL: http://www.inoh.org/ PMID:22120663

  19. Microgravity-induced alterations in signal transduction in cells of the immune system

    NASA Astrophysics Data System (ADS)

    Paulsen, Katrin; Thiel, Cora; Timm, Johanna; Schmidt, Peter M.; Huber, Kathrin; Tauber, Svantje; Hemmersbach, Ruth; Seibt, Dieter; Kroll, Hartmut; Grote, Karl-Heinrich; Zipp, Frauke; Schneider-Stock, Regine; Cogoli, Augusto; Hilliger, Andre; Engelmann, Frank; Ullrich, Oliver

    2010-11-01

    Since decades it is known that the activity of cells of the immune system is severely dysregulated in microgravity, however, the underlying molecular aspects have not been elucidated yet. The identification of gravity-sensitive molecular mechanisms in cells of the immune system is an important and indispensable prerequisite for the development of counteractive measures to prevent or treat disturbed immune cell function of astronauts during long-term space missions. Moreover, their sensitivity to altered gravity renders immune cells an ideal model system to understand if and how gravity on Earth is required for normal mammalian cell function and signal transduction. We investigated the effect of simulated weightlessness (2D clinostat) and of real microgravity (parabolic flights) on key signal pathways in a human monocytic and a T lymphocyte cell line. We found that cellular responses to microgravity strongly depend on the cell-type and the conditions in which the cells are subjected to microgravity. In Jurkat T cells, enhanced phosphorylation of the MAP kinases ERK-1/2, MEK and p38 and inhibition of nuclear translocation of NF-kB were the predominant responses to simulated weightlessness, in either stimulated or non-stimulated cells. In contrast, non-stimulated monocytic U937 cells responded to simulated weightlessness with enhanced overall tyrosine-phosphorylation and activation of c-jun, whereas PMA-stimulated U937 cells responded the opposite way with reduced tyrosine-phosphorylation and reduced activation of c-jun, compared with PMA-stimulated 1 g controls. P53 protein was phosphorylated rapidly in microgravity. The identification of gravi-sensitive mechanisms in cells of the immune system will not only enable us to understand and prevent the negative effects of long time exposure to microgravity on Astronauts, but could also lead to novel therapeutic targets in general.

  20. Calcium and protein phosphorylation in the transduction of gravity signal in corn roots

    NASA Technical Reports Server (NTRS)

    Friedmann, M.; Poovaiah, B. W.

    1991-01-01

    The involvement of calcium and protein phosphorylation in the transduction of gravity signal was studied using corn roots of a light-insensitive variety (Zea mays L., cv. Patriot). The gravitropic response was calcium-dependent. Horizontal placement of roots preloaded with 32P for three minutes resulted in changes in protein phosphorylation of polypeptides of 32 and 35 kD. Calcium depletion resulted in decreased phosphorylation of these phosphoproteins and replenishment of calcium restored the phosphorylation.

  1. Heavy metal accumulation and signal transduction in herbaceous and woody plants: Paving the way for enhancing phytoremediation efficiency.

    PubMed

    Luo, Zhi-Bin; He, Jiali; Polle, Andrea; Rennenberg, Heinz

    2016-11-01

    Heavy metal (HM)-accumulating herbaceous and woody plants are employed for phytoremediation. To develop improved strategies for enhancing phytoremediation efficiency, knowledge of the microstructural, physiological and molecular responses underlying HM-accumulation is required. Here we review the progress in understanding the structural, physiological and molecular mechanisms underlying HM uptake, transport, sequestration and detoxification, as well as the regulation of these processes by signal transduction in response to HM exposure. The significance of genetic engineering for enhancing phytoremediation efficiency is also discussed. In herbaceous plants, HMs are taken up by roots and transported into the root cells via transmembrane carriers for nutritional ions. The HMs absorbed by root cells can be further translocated to the xylem vessels and unloaded into the xylem sap, thereby reaching the aerial parts of plants. HMs can be sequestered in the cell walls, vacuoles and the Golgi apparatuses. Plant roots initially perceive HM stress and trigger the signal transduction, thereby mediating changes at the molecular, physiological, and microstructural level. Signaling molecules such as phytohormones, reactive oxygen species (ROS) and nitric oxide (NO), modulate plant responses to HMs via differentially expressed genes, activation of the antioxidative system and coordinated cross talk among different signaling molecules. A number of genes participated in HM uptake, transport, sequestration and detoxification have been functionally characterized and transformed to target plants for enhancing phytoremediation efficiency. Fast growing woody plants hold an advantage over herbaceous plants for phytoremediation in terms of accumulation of high HM-amounts in their large biomass. Presumably, woody plants accumulate HMs using similar mechanisms as herbaceous counterparts, but the processes of HM accumulation and signal transduction can be more complex in woody plants.

  2. Heavy metal accumulation and signal transduction in herbaceous and woody plants: Paving the way for enhancing phytoremediation efficiency.

    PubMed

    Luo, Zhi-Bin; He, Jiali; Polle, Andrea; Rennenberg, Heinz

    2016-11-01

    Heavy metal (HM)-accumulating herbaceous and woody plants are employed for phytoremediation. To develop improved strategies for enhancing phytoremediation efficiency, knowledge of the microstructural, physiological and molecular responses underlying HM-accumulation is required. Here we review the progress in understanding the structural, physiological and molecular mechanisms underlying HM uptake, transport, sequestration and detoxification, as well as the regulation of these processes by signal transduction in response to HM exposure. The significance of genetic engineering for enhancing phytoremediation efficiency is also discussed. In herbaceous plants, HMs are taken up by roots and transported into the root cells via transmembrane carriers for nutritional ions. The HMs absorbed by root cells can be further translocated to the xylem vessels and unloaded into the xylem sap, thereby reaching the aerial parts of plants. HMs can be sequestered in the cell walls, vacuoles and the Golgi apparatuses. Plant roots initially perceive HM stress and trigger the signal transduction, thereby mediating changes at the molecular, physiological, and microstructural level. Signaling molecules such as phytohormones, reactive oxygen species (ROS) and nitric oxide (NO), modulate plant responses to HMs via differentially expressed genes, activation of the antioxidative system and coordinated cross talk among different signaling molecules. A number of genes participated in HM uptake, transport, sequestration and detoxification have been functionally characterized and transformed to target plants for enhancing phytoremediation efficiency. Fast growing woody plants hold an advantage over herbaceous plants for phytoremediation in terms of accumulation of high HM-amounts in their large biomass. Presumably, woody plants accumulate HMs using similar mechanisms as herbaceous counterparts, but the processes of HM accumulation and signal transduction can be more complex in woody plants. PMID

  3. The discovery of signal transduction by G proteins. A personal account and an overview of the initial findings and contributions that led to our present understanding

    PubMed Central

    Birnbaumer, Lutz

    2007-01-01

    The realization that there existed a G-protein coupled signal transduction mechanism developed gradually and was initially the result of an ill fated quest for uncovering the mechanism of action of insulin, followed by a refocused research in many laboratories, including mine, on how GTP acted to increase hormonal stimulation of adenylyl cyclase. Independent research into how light-activated rhodopsin triggers a response in photoreceptor cells of the retina and the attendant biochemical studies joined midway and, without the left hand knowing well what the right hand was doing, preceded classical G protein research in identifying the molecular players responsible for signal transduction by G proteins. PMID:17141178

  4. Manipulation of light signal transduction as a means of modifying fruit nutritional quality in tomato.

    PubMed

    Liu, Yongsheng; Roof, Sherry; Ye, Zhibiao; Barry, Cornelius; van Tuinen, Ageeth; Vrebalov, Julia; Bowler, Chris; Giovannoni, Jim

    2004-06-29

    Fruit constitutes a major component of human diets, providing fiber, vitamins, and phytonutrients. Carotenoids are a major class of compounds found in many fruits, providing nutritional benefits as precursors to essential vitamins and as antioxidants. Although recent gene isolation efforts and metabolic engineering have primarily targeted genes involved in carotenoid biosynthesis, factors that regulate flux through the carotenoid pathway remain largely unknown. Characterization of the tomato high-pigment mutations (hp1 and hp2) suggests the manipulation of light signal transduction machinery may be an effective approach toward practical manipulation of plant carotenoids. We demonstrate here that hp1 alleles represent mutations in a tomato UV-DAMAGED DNA-BINDING PROTEIN 1 (DDB1) homolog. We further demonstrate that two tomato light signal transduction genes, LeHY5 and LeCOP1LIKE, are positive and negative regulators of fruit pigmentation, respectively. Down-regulated LeHY5 plants exhibit defects in light responses, including inhibited seedling photomorphogenesis, loss of thylakoid organization, and reduced carotenoid accumulation. In contrast, repression of LeCOP1LIKE expression results in plants with exaggerated photomorphogenesis, dark green leaves, and elevated fruit carotenoid levels. These results suggest genes encoding components of light signal transduction machinery also influence fruit pigmentation and represent genetic tools for manipulation of fruit quality and nutritional value.

  5. Transcriptome Analysis of Gerbera hybrida Ray Florets: Putative Genes Associated with Gibberellin Metabolism and Signal Transduction

    PubMed Central

    Kuang, Qi; Li, Lingfei; Peng, Jianzong; Sun, Shulan; Wang, Xiaojing

    2013-01-01

    In this study, the transcriptome of the Gerbera hybrida ray floret was constructed using a high-throughput Illumina sequencing platform. All 47,104 UniGenes with an average length of 845 nt and an N50 equaling 1321 nt were generated from 72,688,546 total primary reads after filtering and assembly. A total of 36,693 transcripts were annotated by comparison with non-redundant National Center for Biotechnology Information (NCBI) protein (Nr), non-redundant NCBI nucleotide (Nt), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases after removing exogenous contaminated sequences. The majority of the genes that are associated with gibberellin metabolism and signal transduction were identified. The targets for signal transduction of other plant hormones were also enumerated. Our study provides a systematic overview of the hormone signal transduction genes that are involved in ray floral development in Asteraceae and should facilitate further understanding of the crucial roles of phytohormones in plant growth. PMID:23472101

  6. Gravity persistent signal 1 reveals a novel cytochrome P450 involved in gravitropic signal transduction

    NASA Astrophysics Data System (ADS)

    Wyatt, Sarah

    is involved in gravitropic signal transduction. (Partially support by NSF: 0618506 to SEW)

  7. Transfer functions for protein signal transduction: application to a model of striatal neural plasticity.

    PubMed

    Scheler, Gabriele

    2013-01-01

    We present a novel formulation for biochemical reaction networks in the context of protein signal transduction. The model consists of input-output transfer functions, which are derived from differential equations, using stable equilibria. We select a set of "source" species, which are interpreted as input signals. Signals are transmitted to all other species in the system (the "target" species) with a specific delay and with a specific transmission strength. The delay is computed as the maximal reaction time until a stable equilibrium for the target species is reached, in the context of all other reactions in the system. The transmission strength is the concentration change of the target species. The computed input-output transfer functions can be stored in a matrix, fitted with parameters, and even recalled to build dynamical models on the basis of state changes. By separating the temporal and the magnitudinal domain we can greatly simplify the computational model, circumventing typical problems of complex dynamical systems. The transfer function transformation of biochemical reaction systems can be applied to mass-action kinetic models of signal transduction. The paper shows that this approach yields significant novel insights while remaining a fully testable and executable dynamical model for signal transduction. In particular we can deconstruct the complex system into local transfer functions between individual species. As an example, we examine modularity and signal integration using a published model of striatal neural plasticity. The modularizations that emerge correspond to a known biological distinction between calcium-dependent and cAMP-dependent pathways. Remarkably, we found that overall interconnectedness depends on the magnitude of inputs, with higher connectivity at low input concentrations and significant modularization at moderate to high input concentrations. This general result, which directly follows from the properties of individual transfer

  8. Guard Cell Signal Transduction Network: Advances in Understanding Abscisic Acid, CO2, and Ca2+ Signaling

    PubMed Central

    Kim, Tae-Houn; Böhmer, Maik; Hu, Honghong; Nishimura, Noriyuki; Schroeder, Julian I.

    2011-01-01

    Stomatal pores are formed by pairs of specialized epidermal guard cells and serve as major gateways for both CO2 influx into plants from the atmosphere and transpirational water loss of plants. Because they regulate stomatal pore apertures via integration of both endogenous hormonal stimuli and environmental signals, guard cells have been highly developed as a model system to dissect the dynamics and mechanisms of plant-cell signaling. The stress hormone ABA and elevated levels of CO2 activate complex signaling pathways in guard cells that are mediated by kinases/phosphatases, secondary messengers, and ion channel regulation. Recent research in guard cells has led to a new hypothesis for how plants achieve specificity in intracellular calcium signaling: CO2 and ABA enhance (prime) the calcium sensitivity of downstream calcium-signaling mechanisms. Recent progress in identification of early stomatal signaling components are reviewed here, including ABA receptors and CO2-binding response proteins, as well as systems approaches that advance our understanding of guard cell-signaling mechanisms. PMID:20192751

  9. Direct sensing and signal transduction during bacterial chemotaxis toward aromatic compounds in Comamonas testosteroni.

    PubMed

    Huang, Zhou; Ni, Bin; Jiang, Cheng-Ying; Wu, Yu-Fan; He, Yun-Zhe; Parales, Rebecca E; Liu, Shuang-Jiang

    2016-07-01

    Micro-organisms sense and chemotactically respond to aromatic compounds. Although the existence of chemoreceptors that bind to aromatic attractants and subsequently trigger chemotaxis have long been speculated, such a chemoreceptor has not been demonstrated. In this report, we demonstrated that the chemoreceptor MCP2901 from Comamonas testosteroni CNB-1 binds to aromatic compounds and initiates downstream chemotactic signaling in addition to its ability to trigger chemotaxis via citrate binding. The function of gene MCP2901 was investigated by genetic deletion from CNB-1 and genetic complementation of the methyl-accepting chemotaxis protein (MCP)-null mutant CNB-1Δ20. Results showed that the expression of MCP2901 in the MCP-null mutant restored chemotaxis toward nine tested aromatic compounds and nine carboxylic acids. Isothermal titration calorimetry (ITC) analyses demonstrated that the ligand-binding domain of MCP2901 (MCP2901LBD) bound to citrate, and weakly to gentisate and 4-hydroxybenzoate. Additionally, ITC assays indicated that MCP2901LBD bound strongly to 2,6-dihydroxybenzoate and 2-hydroxybenzoate, which are isomers of gentisate and 4-hydroxybenzoate respectively that are not metabolized by CNB-1. Agarose-in-plug and capillary assays showed that these two molecules serve as chemoattractants for CNB-1. Through constructing membrane-like MCP2901-inserted Nanodiscs and phosphorelay activity assays, we demonstrated that 2,6-dihydroxybenzoate and 2-hydroxybenzoate altered kinase activity of CheA. This is the first evidence of an MCP binding to an aromatic molecule and triggering signal transduction for bacterial chemotaxis.

  10. Identification of intracellular domains in the growth hormone receptor involved in signal transduction

    SciTech Connect

    Billestrup, N.; Allevato, G.; Moldrup, A.

    1994-12-31

    The growth hormone (GH) receptor belongs to the GH/prolactin/cytokine super-family of receptors. The signal transduction mechanism utilized by this class of receptors remains largely unknown. In order to identify functional domains in the intracellular region of the GH receptor we generated a number of GH receptor mutants and analyzed their function after transfection into various cell lines. A truncated GH receptor missing 184 amino acids at the C-terminus was unable to medite GH effects on transcription of the Spi 2.1 and insulin genes. However, this mutant was fully active in mediating GH-stimulated metabolic effects such as protein synthesis and lipolysis. Furthermore, this mutant GH receptor internalized rapidly following GH binding. Another truncated GH receptor lacking all but five amino acids of the cytoplasmic domain could not mediate any effects of GH nor did it internalize. Deletion of the proline-rich region or changing the four prolines to alanines also resulted in a GH receptor deficient in signaling. Mutation of phenylalanine 346 to alanine resulted in a GH receptor which did not internalize rapidly; however, this mutant GH receptor was capable of mediating GH-stimulated transcription as well as metabolic effects. These results indicate that the intracellular part of the GH receptor can be divided into at least three functional domains: (1) for transcriptional activity, two domains are involved, one located in the C-terminal 184 amino acids and the other in the proline-rich domain; (2) for metabolic effects, a domain located in or near the proline-rich region is of importance; and (3) for internalization, phenylalanine 346 is necessary. 28 refs., 1 fig.

  11. Adaptation to Environmental Stimuli within the Host: Two-Component Signal Transduction Systems of Mycobacterium tuberculosis

    PubMed Central

    Bretl, Daniel J.; Demetriadou, Chrystalla; Zahrt, Thomas C.

    2011-01-01

    Summary: Pathogenic microorganisms encounter a variety of environmental stresses following infection of their respective hosts. Mycobacterium tuberculosis, the etiological agent of tuberculosis, is an unusual bacterial pathogen in that it is able to establish lifelong infections in individuals within granulomatous lesions that are formed following a productive immune response. Adaptation to this highly dynamic environment is thought to be mediated primarily through transcriptional reprogramming initiated in response to recognition of stimuli, including low-oxygen tension, nutrient depletion, reactive oxygen and nitrogen species, altered pH, toxic lipid moieties, cell wall/cell membrane-perturbing agents, and other environmental cues. To survive continued exposure to these potentially adverse factors, M. tuberculosis encodes a variety of regulatory factors, including 11 complete two-component signal transduction systems (TCSSs) and several orphaned response regulators (RRs) and sensor kinases (SKs). This report reviews our current knowledge of the TCSSs present in M. tuberculosis. In particular, we discuss the biochemical and functional characteristics of individual RRs and SKs, the environmental stimuli regulating their activation, the regulons controlled by the various TCSSs, and the known or postulated role(s) of individual TCSSs in the context of M. tuberculosis physiology and/or pathogenesis. PMID:22126994

  12. Remodeling the clock: coactivators and signal transduction in the circadian clockworks

    NASA Astrophysics Data System (ADS)

    Weber, Frank

    2009-03-01

    Most organisms on earth such as cyanobacteria, fungi, plants, insects, animals, and humans synchronize their physiological and behavioral activities with the environmental cycles of day and night. Significant progress has been made in unraveling the genetic components that constitute a molecular circadian clock, which facilitates the temporal control of physiology and behavior. Clock genes assemble interlocked transcriptional/translational feedback loops that underlie the circadian oscillations. Recent investigations revealed that posttranslational regulation of clock proteins is crucial for functioning of the molecular oscillator and for precise temporal control of circadian transcription. This review provides an overview of the homologous clockworks in Drosophila and mammals, with a special focus on recent insights in the posttranslational regulation of clock proteins as well as the role of coactivators, repressors, and signal transduction for circadian controlled genome-wide transcription. The emerging mechanisms of clock gene regulation provide an understanding of the temporal control of transcription in general and the circadian orchestration of physiology and behavior in particular.

  13. Regulation of mRNA export by the PI3 kinase/AKT signal transduction pathway

    PubMed Central

    Quaresma, Alexandre Jose Christino; Sievert, Rachel; Nickerson, Jeffrey A.

    2013-01-01

    UAP56, ALY/REF, and NXF1 are mRNA export factors that sequentially bind at the 5′ end of a nuclear mRNA but are also reported to associate with the exon junction complex (EJC). To screen for signal transduction pathways regulating mRNA export complex assembly, we used fluorescence recovery after photobleaching to measure the binding of mRNA export and EJC core proteins in nuclear complexes. The fraction of UAP56, ALY/REF, and NXF1 tightly bound in complexes was reduced by drug inhibition of the phosphatidylinositide 3-kinase (PI3 kinase)/AKT pathway, as was the tightly bound fraction of the core EJC proteins eIF4A3, MAGOH, and Y14. Inhibition of the mTOR mTORC1 pathway decreased the tight binding of MAGOH. Inhibition of the PI3 kinase/AKT pathway increased the export of poly(A) RNA and of a subset of candidate mRNAs. A similar effect of PI3 kinase/AKT inhibition was observed for mRNAs from both intron-containing and intronless histone genes. However, the nuclear export of mRNAs coding for proteins targeted to the endoplasmic reticulum or to mitochondria was not affected by the PI3 kinase/AKT pathway. These results show that the active PI3 kinase/AKT pathway can regulate mRNA export and promote the nuclear retention of some mRNAs. PMID:23427269

  14. Rho/Rock signal transduction pathway is required for MSC tenogenic differentiation

    PubMed Central

    Maharam, Edward; Yaport, Miguel; Villanueva, Nathaniel L; Akinyibi, Takintope; Laudier, Damien; He, Zhiyong; Leong, Daniel J; Sun, Hui B

    2015-01-01

    Mesenchymal stem cell (MSC)-based treatments have shown promise for improving tendon healing and repair. MSCs have the potential to differentiate into multiple lineages in response to select chemical and physical stimuli, including into tenocytes. Cell elongation and cytoskeletal tension have been shown to be instrumental to the process of MSC differentiation. Previous studies have shown that inhibition of stress fiber formation leads MSCs to default toward an adipogenic lineage, which suggests that stress fibers are required for MSCs to sense the environmental factors that can induce differentiation into tenocytes. As the Rho/ROCK signal transduction pathway plays a critical role in both stress fiber formation and in cell sensation, we examined whether the activation of this pathway was required when inducing MSC tendon differentiation using rope-like silk scaffolds. To accomplish this, we employed a loss-of-function approach by knocking out ROCK, actin and myosin (two other components of the pathway) using the specific inhibitors Y-27632, Latrunculin A and blebbistatin, respectively. We demonstrated that independently disrupting the cytoskeleton and the Rho/ROCK pathway abolished the expression of tendon differentiation markers and led to a loss of spindle morphology. Together, these studies suggest that the tension that is generated by MSC elongation is essential for MSC teno-differentiation and that the Rho/ROCK pathway is a critical mediator of tendon differentiation on rope-like silk scaffolds. PMID:26509098

  15. Functional characterization of WalRK: A two-component signal transduction system from Bacillus anthracis.

    PubMed

    Dhiman, Alisha; Bhatnagar, Sonika; Kulshreshtha, Parul; Bhatnagar, Rakesh

    2014-01-01

    Two-component signal transduction systems (TCS), consisting of a sensor histidine protein kinase and its cognate response regulator, are an important mode of environmental sensing in bacteria. Additionally, they have been found to regulate virulence determinants in several pathogens. Bacillus anthracis, the causative agent of anthrax and a bioterrorism agent, harbours 41 pairs of TCS. However, their role in its pathogenicity has remained largely unexplored. Here, we show that WalRK of B. anthracis forms a functional TCS which exhibits some species-specific functions. Biochemical studies showed that domain variants of WalK, the histidine kinase, exhibit classical properties of autophosphorylation and phosphotransfer to its cognate response regulator WalR. Interestingly, these domain variants also show phosphatase activity towards phosphorylated WalR, thereby making WalK a bifunctional histidine kinase/phosphatase. An in silico regulon determination approach, using a consensus binding sequence from Bacillus subtilis, provided a list of 30 genes that could form a putative WalR regulon in B. anthracis. Further, electrophoretic mobility shift assay was used to show direct binding of purified WalR to the upstream regions of three putative regulon candidates, an S-layer protein EA1, a cell division ABC transporter FtsE and a sporulation histidine kinase KinB3. Our work lends insight into the species-specific functions and mode of action of B. anthracis WalRK. PMID:24490131

  16. A Model for Carrier-Mediated Biological Signal Transduction Based on Equilibrium Ligand Binding Theory.

    PubMed

    Martini, Johannes W R; Schlather, Martin; Schütz, Stefan

    2016-05-01

    Different variants of a mathematical model for carrier-mediated signal transduction are introduced with focus on the odor dose-electrophysiological response curve of insect olfaction. The latter offers a unique opportunity to observe experimentally the effect of an alteration in the carrier molecule composition on the signal molecule-dependent response curve. Our work highlights the role of involved carrier molecules, which have largely been ignored in mathematical models for response curves in the past. The resulting model explains how the involvement of more than one carrier molecule in signal molecule transport can cause dose-response curves as observed in experiments, without the need of more than one receptor per neuron. In particular, the model has the following features: (1) An extended sensitivity range of neuronal response is implemented by a system consisting of only one receptor but several carrier molecules with different affinities for the signal molecule. (2) Given that the sensitivity range is extended by the involvement of different carrier molecules, the model implies that a strong difference in the expression levels of the carrier molecules is absolutely essential for wide range responses. (3) Complex changes in dose-response curves which can be observed when the expression levels of carrier molecules are altered experimentally can be explained by interactions between different carrier molecules. The principles we demonstrate here for electrophysiological responses can also be applied to any other carrier-mediated biological signal transduction process. The presented concept provides a framework for modeling and statistical analysis of signal transduction processes if sufficient information on the underlying biology is available.

  17. Structural insights of homotypic interaction domains in the ligand-receptor signal transduction of tumor necrosis factor (TNF)

    PubMed Central

    Park, Young-Hoon; Jeong, Mi Suk; Jang, Se Bok

    2016-01-01

    Several members of tumor necrosis factor receptor (TNFR) superfamily that these members activate caspase-8 from death-inducing signaling complex (DISC) in TNF ligand-receptor signal transduction have been identified. In the extrinsic pathway, apoptotic signal transduction is induced in death domain (DD) superfamily; it consists of a hexahelical bundle that contains 80 amino acids. The DD superfamily includes about 100 members that belong to four subfamilies: death domain (DD), caspase recruitment domain (CARD), pyrin domain (PYD), and death effector domain (DED). This superfamily contains key building blocks: with these blocks, multimeric complexes are formed through homotypic interactions. Furthermore, each DD-binding event occurs exclusively. The DD superfamily regulates the balance between death and survival of cells. In this study, the structures, functions, and unique features of DD superfamily members are compared with their complexes. By elucidating structural insights of DD superfamily members, we investigate the interaction mechanisms of DD domains; these domains are involved in TNF ligand-receptor signaling. These DD superfamily members play a pivotal role in the development of more specific treatments of cancer. [BMB Reports 2016; 49(3): 159-166] PMID:26615973

  18. Small-Molecule Inhibitors of Cytokine-Mediated STAT1 Signal Transduction In β-Cells With Improved Aqueous Solubility

    PubMed Central

    Scully, Stephen S.; Tang, Alicia J.; Lundh, Morten; Mosher, Carrie M.; Perkins, Kedar M.; Wagner, Bridget K.

    2013-01-01

    We previously reported the discovery of BRD0476 (1), a small molecule generated by diversity-oriented synthesis that suppresses cytokine-induced β-cell apoptosis. Herein, we report the synthesis and biological evaluation of 1 and analogs with improved aqueous solubility. By replacing naphthyl with quinoline moieties, we prepared active analogs with up to a 1400-fold increase in solubility from 1. In addition, we demonstrated that compound 1 and analogs inhibit STAT1 signal transduction induced by IFN-γ. PMID:23617753

  19. Cytoplasmic RNA modulators of an inside-out signal-transduction cascade

    PubMed Central

    Blind, Michael; Kolanus, Waldemar; Famulok, Michael

    1999-01-01

    A vaccinia virus-based RNA expression system enabled high-level cytoplasmic expression of RNA aptamers directed against the intracellular domain of the β2 integrin LFA-1, a transmembrane protein that mediates cell adhesion to intercellular adhesion molecule-1 (ICAM-1). In two different cell types, cytoplasmic expression of integrin-binding aptamers reduced inducible cell adhesion to ICAM-1. The aptamers specifically target, and thereby define, a functional cytoplasmic subdomain important for the regulation of cell adhesion in leukocytes. Our approach of aptamer-controlled blocking of signaling pathways in vivo could potentially be applied wherever targeted modulation of a signal-transduction cascade is desired. PMID:10097084

  20. Synaptic signal transduction aided by noise in a dynamical saturating model

    NASA Astrophysics Data System (ADS)

    Chapeau-Blondeau, François; Duan, Fabing; Abbott, Derek

    2010-02-01

    A generic dynamical model with saturation for neural signal transduction at the synaptic stage is presented. Analysis of this model of a synaptic pathway demonstrates its ability to give rise to stochastic resonance or improvement by noise, at this stage of signal transmission. Beyond the case of the intrinsic threshold nonlinearity of the neuron response, the results extend the feasibility of stochastic resonance to neural saturating dynamics at the synaptic stage. The present results also constitute the exposition of a new type of nonlinear (saturating) dynamics capable of stochastic resonance.

  1. Towards biochemical filters with a sigmoidal response to pH changes: buffered biocatalytic signal transduction

    NASA Astrophysics Data System (ADS)

    Pita, Marcos; Privman, Vladimir; Arugula, Mary A.; Melnikov, Dmitriy; Bocharova, Vera; Katz, Evgeny

    We realize a biochemical filtering process by introducing a buffer in a biocatalytic signal-transduction logic system based on the function of an enzyme, esterase. The input, ethyl butyrate, is converted into butyric acid-the output signal, which in turn is measured by the drop in the pH value. The developed approach offers a versatile "network element" for increasing the complexity of biochemical information processing systems. Evaluation of an optimal regime for quality filtering is accomplished in the framework of a kinetic rate-equation model.

  2. Near-Perfect Adaptation in the E. coli Chemotaxis Signal Transduction Network

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Setayeshgar, Sima

    2007-03-01

    Biochemical reaction networks constitute the computing language of the cell, from converting external stimuli into appropriate intracellular signals to regulating gene expression. Precise adaptation is an important property of many signaling networks, allowing compensation for continued stimulation without saturation. Furthermore, a common feature of intracellular reaction networks is the ability to operate in a noisy environment where concentrations of key components, such as signaling molecules and enzymes controlling reaction rates are typically small and therefore fluctuations in their numbers are significant. In the context of the well- characterized E. coli chemotaxis signal transduction network, we present a new computational scheme that explores surfaces in the space of total protein concentrations and reaction rates on which (near-)perfect adaptation holds. The resulting dependencies between parameters provide conditions for (near-)perfect adaptation as well as ranges of numerical values for parameters not reliably known from experiments. We generalize the applicability of this scheme to other signaling networks.

  3. Sphingosine-1-phosphate inhibits PDGF-induced chemotaxis of human arterial smooth muscle cells: spatial and temporal modulation of PDGF chemotactic signal transduction

    PubMed Central

    1995-01-01

    Activation of the PDGF receptor on human arterial smooth muscle cells (SMC) induces migration and proliferation via separable signal transduction pathways. Sphingosine-1-phosphate (Sph-1-P) can be formed following PDGF receptor activation and therefore may be implicated in PDGF-receptor signal transduction. Here we show that Sph-1-P does not significantly affect PDGF-induced DNA synthesis, proliferation, or activation of mitogenic signal transduction pathways, such as the mitogen-activated protein (MAP) kinase cascade and PI 3-kinase, in human arterial SMC. On the other hand, Sph-1-P strongly mimics PDGF receptor-induced chemotactic signal transduction favoring actin filament disassembly. Although Sph-1-P mimics PDGF, exogenously added Sph-1-P induces more prolonged and quantitatively greater PIP2 hydrolysis compared to PDGF-BB, a markedly stronger calcium mobilization and a subsequent increase in cyclic AMP levels and activation of cAMP-dependent protein kinase. This excessive and prolonged signaling favors actin filament disassembly by Sph-1-P, and results in inhibition of actin nucleation, actin filament assembly and formation of focal adhesion sites. Sph-1-P-induced interference with the dynamics of PDGF-stimulated actin filament disassembly and assembly results in a marked inhibition of cell spreading, of extension of the leading lamellae toward PDGF, and of chemotaxis toward PDGF. The results suggest that spatial and temporal changes in phosphatidylinositol turnover, calcium mobilization and actin filament disassembly may be critical to PDGF-induced chemotaxis and suggest a possible role for endogenous Sph-1-P in the regulation of PDGF receptor chemotactic signal transduction. PMID:7790372

  4. The Clickable Guard Cell, Version II: Interactive Model of Guard Cell Signal Transduction Mechanisms and Pathways.

    PubMed

    Kwak, June M; Mäser, Pascal; Schroeder, Julian I

    2008-01-01

    Guard cells are located in the leaf epidermis and pairs of guard cells surround and form stomatal pores, which regulate CO(2) influx from the atmosphere into leaves for photosynthetic carbon fixation. Stomatal guard cells also regulate water loss of plants via transpiration to the atmosphere. Signal transduction mechanisms in guard cells integrate a multitude of different stimuli to modulate stomatal apertures. Stomata open in response to light. Stomata close in response to drought stress, elevated CO(2), ozone and low humidity. In response to drought, plants synthesize the hormone abscisic acid (ABA) that triggers closing of stomatal pores. Guard cells have become a highly developed model system for dissecting signal transduction mechanisms in plants and for elucidating how individual signaling mechanisms can interact within a network in a single cell. Many new findings have been made in the last few years. This chapter is an update of an electronic interactive chapter in the previous edition of The Arabidopsis Book (Mäser et al. 2003). Here we focus on mechanisms for which genes and mutations have been characterized, including signaling components for which there is substantial signaling, biochemical and genetic evidence. Ion channels have been shown to represent targets of early signal transduction mechanisms and provide functional signaling and quantitative analysis points to determine where and how mutations affect branches within the guard cell signaling network. Although a substantial number of genes and proteins that function in guard cell signaling have been identified in recent years, there are many more left to be identified and the protein-protein interactions within this network will be an important subject of future research. A fully interactive clickable electronic version of this publication can be accessed at the following web site: http://www-biology.ucsd.edu/labs/schroeder/clickablegc2/. The interactive clickable version includes the following

  5. Nitric oxide-mediated bystander signal transduction induced by heavy-ion microbeam irradiation.

    PubMed

    Tomita, Masanori; Matsumoto, Hideki; Funayama, Tomoo; Yokota, Yuichiro; Otsuka, Kensuke; Maeda, Munetoshi; Kobayashi, Yasuhiko

    2015-07-01

    In general, a radiation-induced bystander response is known to be a cellular response induced in non-irradiated cells after receiving bystander signaling factors released from directly irradiated cells within a cell population. Bystander responses induced by high-linear energy transfer (LET) heavy ions at low fluence are an important health problem for astronauts in space. Bystander responses are mediated via physical cell-cell contact, such as gap-junction intercellular communication (GJIC) and/or diffusive factors released into the medium in cell culture conditions. Nitric oxide (NO) is a well-known major initiator/mediator of intercellular signaling within culture medium during bystander responses. In this study, we investigated the NO-mediated bystander signal transduction induced by high-LET argon (Ar)-ion microbeam irradiation of normal human fibroblasts. Foci formation by DNA double-strand break repair proteins was induced in non-irradiated cells, which were co-cultured with those irradiated by high-LET Ar-ion microbeams in the same culture plate. Foci formation was suppressed significantly by pretreatment with an NO scavenger. Furthermore, NO-mediated reproductive cell death was also induced in bystander cells. Phosphorylation of NF-κB and Akt were induced during NO-mediated bystander signaling in the irradiated and bystander cells. However, the activation of these proteins depended on the incubation time after irradiation. The accumulation of cyclooxygenase-2 (COX-2), a downstream target of NO and NF-κB, was observed in the bystander cells 6 h after irradiation but not in the directly irradiated cells. Our findings suggest that Akt- and NF-κB-dependent signaling pathways involving COX-2 play important roles in NO-mediated high-LET heavy-ion-induced bystander responses. In addition, COX-2 may be used as a molecular marker of high-LET heavy-ion-induced bystander cells to distinguish them from directly irradiated cells, although this may depend on the time

  6. Nitric oxide-mediated bystander signal transduction induced by heavy-ion microbeam irradiation

    NASA Astrophysics Data System (ADS)

    Tomita, Masanori; Matsumoto, Hideki; Funayama, Tomoo; Yokota, Yuichiro; Otsuka, Kensuke; Maeda, Munetoshi; Kobayashi, Yasuhiko

    2015-07-01

    In general, a radiation-induced bystander response is known to be a cellular response induced in non-irradiated cells after receiving bystander signaling factors released from directly irradiated cells within a cell population. Bystander responses induced by high-linear energy transfer (LET) heavy ions at low fluence are an important health problem for astronauts in space. Bystander responses are mediated via physical cell-cell contact, such as gap-junction intercellular communication (GJIC) and/or diffusive factors released into the medium in cell culture conditions. Nitric oxide (NO) is a well-known major initiator/mediator of intercellular signaling within culture medium during bystander responses. In this study, we investigated the NO-mediated bystander signal transduction induced by high-LET argon (Ar)-ion microbeam irradiation of normal human fibroblasts. Foci formation by DNA double-strand break repair proteins was induced in non-irradiated cells, which were co-cultured with those irradiated by high-LET Ar-ion microbeams in the same culture plate. Foci formation was suppressed significantly by pretreatment with an NO scavenger. Furthermore, NO-mediated reproductive cell death was also induced in bystander cells. Phosphorylation of NF-κB and Akt were induced during NO-mediated bystander signaling in the irradiated and bystander cells. However, the activation of these proteins depended on the incubation time after irradiation. The accumulation of cyclooxygenase-2 (COX-2), a downstream target of NO and NF-κB, was observed in the bystander cells 6 h after irradiation but not in the directly irradiated cells. Our findings suggest that Akt- and NF-κB-dependent signaling pathways involving COX-2 play important roles in NO-mediated high-LET heavy-ion-induced bystander responses. In addition, COX-2 may be used as a molecular marker of high-LET heavy-ion-induced bystander cells to distinguish them from directly irradiated cells, although this may depend on the time

  7. Postsynaptic Signal Transduction Models for Long-Term Potentiation and Depression

    PubMed Central

    Manninen, Tiina; Hituri, Katri; Kotaleski, Jeanette Hellgren; Blackwell, Kim T.; Linne, Marja-Leena

    2010-01-01

    More than a hundred biochemical species, activated by neurotransmitters binding to transmembrane receptors, are important in long-term potentiation (LTP) and long-term depression (LTD). To investigate which species and interactions are critical for synaptic plasticity, many computational postsynaptic signal transduction models have been developed. The models range from simple models with a single reversible reaction to detailed models with several hundred kinetic reactions. In this study, more than a hundred models are reviewed, and their features are compared and contrasted so that similarities and differences are more readily apparent. The models are classified according to the type of synaptic plasticity that is modeled (LTP or LTD) and whether they include diffusion or electrophysiological phenomena. Other characteristics that discriminate the models include the phase of synaptic plasticity modeled (induction, expression, or maintenance) and the simulation method used (deterministic or stochastic). We find that models are becoming increasingly sophisticated, by including stochastic properties, integrating with electrophysiological properties of entire neurons, or incorporating diffusion of signaling molecules. Simpler models continue to be developed because they are computationally efficient and allow theoretical analysis. The more complex models permit investigation of mechanisms underlying specific properties and experimental verification of model predictions. Nonetheless, it is difficult to fully comprehend the evolution of these models because (1) several models are not described in detail in the publications, (2) only a few models are provided in existing model databases, and (3) comparison to previous models is lacking. We conclude that the value of these models for understanding molecular mechanisms of synaptic plasticity is increasing and will be enhanced further with more complete descriptions and sharing of the published models. PMID:21188161

  8. Gravitactic signal transduction elements in Astasia longa investigated during parabolic flights.

    PubMed

    Richter, Peter R; Schuster, Martin; Lebert, Michael; Hader, Donat-P

    2003-01-01

    Euglena gracilis and its close relative Astasia longa show a pronounced negative gravitactic behavior. Many experiments revealed that gravitaxis is most likely mediated by an active physiological mechanism. The goal of the present study was to examine elements in the sensory transduction by means of inhibitors of gravitaxis and the intracellular calcium concentration during short microgravity periods. During the course of six parabolic flights (ESA 31th parabolic flight campaign and DLR 6th parabolic flight campaign) the effects of trifluoperazine (calmodulin inhibitor), caffeine (phosphodiesterase inhibitor) and gadolinium (blocks mechano-sensitive ion channels) was investigated. Due to the extreme parabolic flight maneuvers of the aircraft alternating phases of 1.8 x g(n) (about 20 s) and microgravity (about 22 s) were achieved (g(n): acceleration of Earth's gravity field). The duration of the microgravity periods was sufficient to detect a loss of cell orientation in the samples. In the presence of gadolinium impaired gravitaxis was found during acceleration, while caffeine-treated cells showed, compared to the controls, a very precise gravitaxis and faster reorientation in the 1.8 x g(n) period following microgravity. A transient increase of the intracellular calcium upon increased acceleration was detected also in inhibitor-treated samples. Additionally, it was found that the cells showed a higher calcium signal when they deviated from the vertical swimming direction. In the presence of trifluoperazine a slightly higher general calcium signal was detected compared to untreated controls, while gadolinium was found to decrease the intracellular calcium concentration. In the presence of caffeine no clear changes of intracellular calcium were detected compared to the control.

  9. Universality and diversity in the signal transduction pathway that regulates seasonal reproduction in vertebrates

    PubMed Central

    Nakane, Yusuke; Yoshimura, Takashi

    2014-01-01

    Most vertebrates living outside the tropical zone show robust physiological responses in response to seasonal changes in photoperiod, such as seasonal reproduction, molt, and migration. The highly sophisticated photoperiodic mechanism in Japanese quail has been used to uncover the mechanism of seasonal reproduction. Molecular analysis of quail mediobasal hypothalamus (MBH) revealed that local thyroid hormone activation within the MBH plays a critical role in the photoperiodic response of gonads. This activation is accomplished by two gene switches: thyroid hormone-activating (DIO2) and thyroid hormone-inactivating enzymes (DIO3). Functional genomics studies have shown that long-day induced thyroid-stimulating hormone (TSH) in the pars tuberalis (PT) of the pituitary gland regulates DIO2/3 switching. In birds, light information received directly by deep brain photoreceptors regulates PT TSH. Recent studies demonstrated that Opsin 5-positive cerebrospinal fluid (CSF)-contacting neurons are deep brain photoreceptors that regulate avian seasonal reproduction. Although the involvement of TSH and DIO2/3 in seasonal reproduction has been confirmed in various mammals, the light input pathway that regulates PT TSH in mammals differs from that of birds. In mammals, the eye is the only photoreceptor organ and light information received by the eye is transmitted to the pineal gland through the circadian pacemaker, the suprachiasmatic nucleus. Nocturnal melatonin secretion from the pineal gland indicates the length of night and regulates the PT TSH. In fish, the regulatory machinery for seasonal reproduction, from light input to neuroendocrine output, has been recently demonstrated in the coronet cells of the saccus vasculosus (SV). The SV is unique to fish and coronet cells are CSF-contacting neurons. Here, we discuss the universality and diversity of signal transduction pathways that regulate vertebrate seasonal reproduction. PMID:24959116

  10. Listeria monocytogenes induced Rac1-dependent signal transduction in endothelial cells.

    PubMed

    Schmeck, Bernd; Beermann, Wiebke; van Laak, Vincent; Opitz, Bastian; Hocke, Andreas C; Meixenberger, Karolin; Eitel, Julia; Chakraborty, Trinad; Schmidt, Gudula; Barth, Holger; Suttorp, Norbert; Hippenstiel, Stefan

    2006-11-30

    Infection of endothelial cells by Listeria monocytogenes is an essential step in the pathogenesis of listeriosis. Small GTPases of the Rho family act as molecular switches in signal transduction. We tested the hypothesis that Rho GTPases contribute to the regulation of cytokine expression following L. monocytogenes infection. L. monocytogenes induced release of distinct CC and CXC, as well as Th1 and Th2 cytokines and growth factors by endothelial cells and activated RhoA and Rac1. Inhibition of Rac1 by inhibitor Nsc23766 reduced cytokine expression, and slightly yet significantly the uptake of bacteria. Blocking of Rho proteins by Clostridium difficile toxin B-10463 (TcdB) reduced Listeria-dependent cytokine expression, whereas activating Rho proteins by Escherichia coli CNF1 increased it. We analyzed regulation of IL-8 expression in more detail: Listeria-induced IL-8 release was reduced by inhibition of RhoA, Rac1 and Cdc42 (TcdB) or Rac1 while blocking of RhoA/B/C by Clostridium limosum C3 fusion toxin (C3FT) or Rho kinase by Y27632 reduced cytokine expression only slightly. Activation of RhoA, Rac1 and Cdc42 (CNF1), but not of RhoA alone (CNF(Y)), enhanced Listeria-dependent IL-8 release significantly. Furthermore, inhibition of RhoA, Rac1 and Cdc42 (TcdB) and Rac1 (Nsc23766), but not of RhoA (C3FT) reduced Listeria-related recruitment of NF-kappaB/p65 and RNA polymerase II to the il8 promoter, as well as acetylation of histone H4 and Ser10/Lys14-phosphorylation/acetylation of histone H3 at the il8 gene promoter in HUVEC. In conclusion, Rac1 contributed to L. monocytogenes-induced cytokine expression by human endothelial cells.

  11. A Novel Signal Transduction Pathway that Modulates rhl Quorum Sensing and Bacterial Virulence in Pseudomonas aeruginosa

    PubMed Central

    Chen, Feifei; Xia, Yongjie; Lou, Jingyu; Zhang, Xue; Yang, Nana; Sun, Xiaoxu; Zhang, Qin; Zhuo, Chao; Huang, Xi; Deng, Xin; Yang, Cai-Guang; Ye, Yan; Zhao, Jing; Wu, Min; Lan, Lefu

    2014-01-01

    The rhl quorum-sensing (QS) system plays critical roles in the pathogenesis of P. aeruginosa. However, the regulatory effects that occur directly upstream of the rhl QS system are poorly understood. Here, we show that deletion of gene encoding for the two-component sensor BfmS leads to the activation of its cognate response regulator BfmR, which in turn directly binds to the promoter and decreases the expression of the rhlR gene that encodes the QS regulator RhlR, causing the inhibition of the rhl QS system. In the absence of bfmS, the Acka-Pta pathway can modulate the regulatory activity of BfmR. In addition, BfmS tunes the expression of 202 genes that comprise 3.6% of the P. aeruginosa genome. We further demonstrate that deletion of bfmS causes substantially reduced virulence in lettuce leaf, reduced cytotoxicity, enhanced invasion, and reduced bacterial survival during acute mouse lung infection. Intriguingly, specific missense mutations, which occur naturally in the bfmS gene in P. aeruginosa cystic fibrosis (CF) isolates such as DK2 strains and RP73 strain, can produce BfmS variants (BfmSL181P, BfmSL181P/E376Q, and BfmSR393H) that no longer repress, but instead activate BfmR. As a result, BfmS variants, but not the wild-type BfmS, inhibit the rhl QS system. This study thus uncovers a previously unexplored signal transduction pathway, BfmS/BfmR/RhlR, for the regulation of rhl QS in P. aeruginosa. We propose that BfmRS TCS may have an important role in the regulation and evolution of P. aeruginosa virulence during chronic infection in CF lungs. PMID:25166864

  12. Chromium stress response effect on signal transduction and expression of signaling genes in rice.

    PubMed

    Trinh, Ngoc-Nam; Huang, Tsai-Lien; Chi, Wen-Chang; Fu, Shih-Feng; Chen, Chi-Chien; Huang, Hao-Jen

    2014-02-01

    Hexavalent chromium [Cr(VI)] is a non-essential metal for normal plants and is toxic to plants at high concentrations. However, signaling pathways and molecular mechanisms of its action on cell function and gene expression remain elusive. In this study, we found that Cr(VI) induced endogenous reactive oxygen species (ROS) generation and Ca(2+) accumulation and activated NADPH oxidase and calcium-dependent protein kinase. We investigated global transcriptional changes in rice roots by microarray analysis. Gene expression profiling indicated activation of abscisic acid-, ethylene- and jasmonic acid-mediated signaling and inactivation of gibberellic acid-related pathways in Cr(VI) stress-treated rice roots. Genes encoding signaling components such as the protein kinases domain of unknown function 26, receptor-like cytoplasmic kinase, LRK10-like kinase type 2 and protein phosphatase 2C, as well as transcription factors WRKY and apetala2/ethylene response factor were predominant during Cr(VI) stress. Genes involved in vesicle trafficking were subjected to functional characterization. Pretreating rice roots with a vesicle trafficking inhibitor, brefeldin A, effectively reduced Cr(VI)-induced ROS production. Suppression of the vesicle trafficking gene, Exo70, by virus-induced gene silencing strategies revealed that vesicle trafficking is required for mediation of Cr(VI)-induced ROS production. Taken together, these findings shed light on the molecular mechanisms in signaling pathways and transcriptional regulation in response to Cr stress in plants. PMID:24033343

  13. Oxidative Stress in Fungi: Its Function in Signal Transduction, Interaction with Plant Hosts, and Lignocellulose Degradation

    PubMed Central

    Breitenbach, Michael; Weber, Manuela; Rinnerthaler, Mark; Karl, Thomas; Breitenbach-Koller, Lore

    2015-01-01

    In this review article, we want to present an overview of oxidative stress in fungal cells in relation to signal transduction, interaction of fungi with plant hosts, and lignocellulose degradation. We will discuss external oxidative stress which may occur through the interaction with other microorganisms or plant hosts as well as internally generated oxidative stress, which can for instance originate from NADPH oxidases or “leaky” mitochondria and may be modulated by the peroxiredoxin system or by protein disulfide isomerases thus contributing to redox signaling. Analyzing redox signaling in fungi with the tools of molecular genetics is presently only in its beginning. However, it is already clear that redox signaling in fungal cells often is linked to cell differentiation (like the formation of perithecia), virulence (in plant pathogens), hyphal growth and the successful passage through the stationary phase. PMID:25854186

  14. Oxidative stress in fungi: its function in signal transduction, interaction with plant hosts, and lignocellulose degradation.

    PubMed

    Breitenbach, Michael; Weber, Manuela; Rinnerthaler, Mark; Karl, Thomas; Breitenbach-Koller, Lore

    2015-01-01

    In this review article, we want to present an overview of oxidative stress in fungal cells in relation to signal transduction, interaction of fungi with plant hosts, and lignocellulose degradation. We will discuss external oxidative stress which may occur through the interaction with other microorganisms or plant hosts as well as internally generated oxidative stress, which can for instance originate from NADPH oxidases or "leaky" mitochondria and may be modulated by the peroxiredoxin system or by protein disulfide isomerases thus contributing to redox signaling. Analyzing redox signaling in fungi with the tools of molecular genetics is presently only in its beginning. However, it is already clear that redox signaling in fungal cells often is linked to cell differentiation (like the formation of perithecia), virulence (in plant pathogens), hyphal growth and the successful passage through the stationary phase. PMID:25854186

  15. The ubiquitin–proteasome system and signal transduction pathways regulating Epithelial Mesenchymal transition of cancer

    PubMed Central

    2012-01-01

    Epithelial to Mesenchymal transition (EMT) in cancer, a process permitting cancer cells to become mobile and metastatic, has a signaling hardwire forged from development. Multiple signaling pathways that regulate carcinogenesis enabling characteristics in neoplastic cells such as proliferation, resistance to apoptosis and angiogenesis are also the main players in EMT. These pathways, as almost all cellular processes, are in their turn regulated by ubiquitination and the Ubiquitin-Proteasome System (UPS). Ubiquitination is the covalent link of target proteins with the small protein ubiquitin and serves as a signal to target protein degradation by the proteasome or to other outcomes such as endocytosis, degradation by the lysosome or specification of cellular localization. This paper reviews signal transduction pathways regulating EMT and being regulated by ubiquitination. PMID:22827778

  16. Unraveling the complex regulatory relationships between metabolism and signal transduction in cancer

    PubMed Central

    Wynn, Michelle L.; Merajver, Sofia D.; Schnell, Santiago

    2013-01-01

    Cancer cells exhibit an altered metabolic phenotype, known as the Warburg effect, which is characterized by high rates of glucose uptake and glycolysis, even under aerobic conditions. The Warburg effect appears to be an intrinsic component of most cancers and there is evidence linking cancer progression to mutations, translocations, and alternative splicing of genes that directly code for or have downstream effects on key metabolic enzymes. Many of the same signaling pathways are routinely dysregulated in cancer and a number of important oncogenic signaling pathways play important regulatory roles in central carbon metabolism. Unraveling the complex regulatory relationship between cancer metabolism and signaling requires the application of systems biology approaches. Here we discuss computational approaches for modeling protein signal transduction and metabolism as well as how the regulatory relationship between these two important cellular processes can be combined into hybrid models. PMID:22161328

  17. Do signal transduction cascades influence survival in triple-negative breast cancer? A preliminary study

    PubMed Central

    Mumm, Jan-Niclas; Kölbl, Alexandra C; Jeschke, Udo; Andergassen, Ulrich

    2016-01-01

    Background Triple-negative breast cancer (TNBC) is a rather aggressive form of breast cancer, comprised by early metastasis formation and reduced overall survival of the affected patients. Steroid hormone receptors and the human epidermal growth factor receptor 2 are not overexpressed, limiting therapeutic options. Therefore, new treatment options have to be investigated. The aim of our preliminary study was to detect coherences between some molecules of intracellular signal transduction pathways and survival of patients with TNBC, in order to obtain some hints for new therapeutical solutions. Methods Thirty-one paraffin-embedded tumor tissue samples, which were determined to be negative for steroid hormone receptors as well as human epidermal growth factor receptor 2, were immunohistochemically stained for a number of signal transduction molecules from several signaling pathways. β-Catenin, HIF1α, MCL, Notch1, LRP6, XBP1, and FOXP3 were stained with specific antibodies, and their staining was correlated with patient survival by Kaplan–Meier analyses. Results Only two of the investigated molecules have shown correlation with overall survival. Cytoplasmic staining of HIF1α and centro-tumoral lymphocyte FOXP3 staining showed statistically significant correlations with survival. Conclusion The coherence of signal transduction molecules with survival of patients with TNBC is still controversially discussed in the literature. Our study comprises one more mosaic stone in the elucidation of these intracellular processes and their influences on patient outcome. Lots of research still has to be done in this field, but it would be worthwhile as it may offer new therapeutic targets for a group of patients with breast cancer, which is still hard to treat. PMID:27307757

  18. A functional TOC complex contributes to gravity signal transduction in Arabidopsis.

    PubMed

    Strohm, Allison K; Barrett-Wilt, Greg A; Masson, Patrick H

    2014-01-01

    Although plastid sedimentation has long been recognized as important for a plant's perception of gravity, it was recently shown that plastids play an additional function in gravitropism. The Translocon at the Outer envelope membrane of Chloroplasts (TOC) complex transports nuclear-encoded proteins into plastids, and a receptor of this complex, Toc132, was previously hypothesized to contribute to gravitropism either by directly functioning as a gravity signal transducer or by indirectly mediating the plastid localization of a gravity signal transducer. Here we show that mutations in multiple genes encoding TOC complex components affect gravitropism in a genetically sensitized background and that the cytoplasmic acidic domain of Toc132 is not required for its involvement in this process. Furthermore, mutations in TOC132 enhance the gravitropic defect of a mutant whose amyloplasts lack starch. Finally, we show that the levels of several nuclear-encoded root proteins are altered in toc132 mutants. These data suggest that the TOC complex indirectly mediates gravity signal transduction in Arabidopsis and support the idea that plastids are involved in gravitropism not only through their ability to sediment but also as part of the signal transduction mechanism.

  19. The Arabidopsis RGA gene encodes a transcriptional regulator repressing the gibberellin signal transduction pathway.

    PubMed

    Silverstone, A L; Ciampaglio, C N; Sun, T

    1998-02-01

    The recessive rga mutation is able to partially suppress phenotypic defects of the Arabidopsis gibberellin (GA) biosynthetic mutant ga1-3. Defects in stem elongation, flowering time, and leaf abaxial trichome initiation are suppressed by rga. This indicates that RGA is a negative regulator of the GA signal transduction pathway. We have identified 10 additional alleles of rga from a fast-neutron mutagenized ga1-3 population and used them to isolate the RGA gene by genomic subtraction. Our data suggest that RGA may be functioning as a transcriptional regulator. RGA was found to be a member of the VHIID regulatory family, which includes the radial root organizing gene SCARECROW and another GA signal transduction repressor, GAI. RGA and GAI proteins share a high degree of homology, but their N termini are more divergent. The presence of several structural features, including homopolymeric serine and threonine residues, a putative nuclear localization signal, leucine heptad repeats, and an LXXLL motif, indicates that the RGA protein may be a transcriptional regulator that represses the GA response. In support of the putative nuclear localization signal, we demonstrated that a transiently expressed green fluorescent protein-RGA fusion protein is localized to the nucleus in onion epidermal cells. Because the rga mutation abolished the high level of expression of the GA biosynthetic gene GA4 in the ga1-3 mutant background, we conclude that RGA may also play a role in controlling GA biosynthesis.

  20. PAT1, a new member of the GRAS family, is involved in phytochrome A signal transduction

    PubMed Central

    Bolle, Cordelia; Koncz, Csaba; Chua, Nam-Hai

    2000-01-01

    Light signaling via the phytochrome A (phyA) photoreceptor controls basic plant developmental processes including de-etiolation and hypocotyl elongation. We have identified a new Arabidopsis mutant, pat (phytochrome A signal transduction)1-1, which shows strongly reduced responses in continuous far-red light. Physiological and molecular data indicate that this mutant is disrupted at an early step of phyA signal transduction. The PAT1 gene encodes a cytoplasmic protein of 490 amino acids with sequence homologies to the plant-specific GRAS regulatory protein family. In the pat1-1 mutant, a T-DNA insertion introduces a premature stop codon, which likely results in the production of a truncated PAT1 protein of 341 amino acids. The semidominant phenotype of this mutant can be recapitulated by overexpression of an appropriately truncated PAT1 gene in the wild type. The results indicate that the truncated PAT1 protein acts in a dominant-negative fashion to inhibit phyA signaling. PMID:10817761

  1. Cellular release of and response to ATP as key determinants of the set-point of signal transduction pathways.

    PubMed

    Ostrom, R S; Gregorian, C; Insel, P A

    2000-04-21

    The determinants of "basal" activity of signaling pathways regulating cellular responses are poorly defined. One possibility is that cells release factors to establish the set-point of such pathways. Here we show that treatment of Madin-Darby canine kidney cells with the nucleotidase apyrase decreases basal arachidonic acid release and cAMP production 30-40% and that inhibitors of P2Y receptor action also affect basal and forskolin-stimulated cAMP accumulation. Changing medium prominently increases extracellular levels of ATP in Madin-Darby canine kidney, COS-7, and HEK-293 cells. Mechanical stimulation of ATP release likely occurs in virtually every experimental protocol with cultured cells, implicating such release and P2Y receptor activation as critical in establishing the set-point for signal transduction pathways. PMID:10766795

  2. Plasticity of the PAS domain and a potential role for signal transduction in the histidine kinase DcuS.

    PubMed

    Etzkorn, Manuel; Kneuper, Holger; Dünnwald, Pia; Vijayan, Vinesh; Krämer, Jens; Griesinger, Christian; Becker, Stefan; Unden, Gottfried; Baldus, Marc

    2008-10-01

    The mechanistic understanding of how membrane-embedded sensor kinases recognize signals and regulate kinase activity is currently limited. Here we report structure-function relationships of the multidomain membrane sensor kinase DcuS using solid-state NMR, structural modeling and mutagenesis. Experimental data of an individual cytoplasmic Per-Arnt-Sim (PAS) domain were compared to structural models generated in silico. These studies, together with previous NMR work on the periplasmic PAS domain, enabled structural investigations of a membrane-embedded 40-kDa construct by solid-state NMR, comprising both PAS segments and the membrane domain. Structural alterations are largely limited to protein regions close to the transmembrane segment. Data from isolated and multidomain constructs favor a disordered N-terminal helix in the cytoplasmic domain. Mutations of residues in this region strongly influence function, suggesting that protein flexibility is related to signal transduction toward the kinase domain and regulation of kinase activity.

  3. Cellular release of and response to ATP as key determinants of the set-point of signal transduction pathways.

    PubMed

    Ostrom, R S; Gregorian, C; Insel, P A

    2000-04-21

    The determinants of "basal" activity of signaling pathways regulating cellular responses are poorly defined. One possibility is that cells release factors to establish the set-point of such pathways. Here we show that treatment of Madin-Darby canine kidney cells with the nucleotidase apyrase decreases basal arachidonic acid release and cAMP production 30-40% and that inhibitors of P2Y receptor action also affect basal and forskolin-stimulated cAMP accumulation. Changing medium prominently increases extracellular levels of ATP in Madin-Darby canine kidney, COS-7, and HEK-293 cells. Mechanical stimulation of ATP release likely occurs in virtually every experimental protocol with cultured cells, implicating such release and P2Y receptor activation as critical in establishing the set-point for signal transduction pathways.

  4. A census of membrane-bound and intracellular signal transduction proteins in bacteria: Bacterial IQ, extroverts and introverts

    PubMed Central

    Galperin, Michael Y

    2005-01-01

    Background Analysis of complete microbial genomes showed that intracellular parasites and other microorganisms that inhabit stable ecological niches encode relatively primitive signaling systems, whereas environmental microorganisms typically have sophisticated systems of environmental sensing and signal transduction. Results This paper presents results of a comprehensive census of signal transduction proteins – histidine kinases, methyl-accepting chemotaxis receptors, Ser/Thr/Tyr protein kinases, adenylate and diguanylate cyclases and c-di-GMP phosphodiesterases – encoded in 167 bacterial and archaeal genomes, sequenced by the end of 2004. The data have been manually checked to avoid false-negative and false-positive hits that commonly arise during large-scale automated analyses and compared against other available resources. The census data show uneven distribution of most signaling proteins among bacterial and archaeal phyla. The total number of signal transduction proteins grows approximately as a square of genome size. While histidine kinases are found in representatives of all phyla and are distributed according to the power law, other signal transducers are abundant in certain phylogenetic groups but virtually absent in others. Conclusion The complexity of signaling systems differs even among closely related organisms. Still, it usually can be correlated with the phylogenetic position of the organism, its lifestyle, and typical environmental challenges it encounters. The number of encoded signal transducers (or their fraction in the total protein set) can be used as a measure of the organism's ability to adapt to diverse conditions, the 'bacterial IQ', while the ratio of transmembrane receptors to intracellular sensors can be used to define whether the organism is an 'extrovert', actively sensing the environmental parameters, or an 'introvert', more concerned about its internal homeostasis. Some of the microorganisms with the highest IQ, including the

  5. New mechanisms of signal transduction inhibitor action: receptor tyrosine kinase down-regulation and blockade of signal transactivation.

    PubMed

    Lee, Adrian V; Schiff, Rachel; Cui, Xiaojiang; Sachdev, Deepali; Yee, Douglas; Gilmore, Andrew P; Streuli, Charles H; Oesterreich, Steffi; Hadsell, Darryl L

    2003-01-01

    The explosion of signal transduction research over the last 10 years has provided a unique insight into the complexity of these intricate pathways. Whereas intermediates of multiple signaling pathways have been identified, understanding their function and, in particular, the interactions between them has become a daunting task. The increasing evidence that many of these pathways can cross-talk with each other via signal transactivation inevitably raises the question of how cells determine specificity in signaling. Despite the mind-numbing complexity of these pathways, progress has been made in developing highly specific and potent signal transduction inhibitors (STIs). STIs show promise in the treatment of cancer in preclinical studies and are currently in a number of clinical trials. Whereas many of these agents were "rationally designed," we barely understand their mechanisms of action. This review will highlight how recent studies using these STIs have elucidated novel mechanisms of STI action that may be used in the development of new therapeutic strategies for the treatment of cancer.

  6. Early abscisic acid signal transduction mechanisms: newly discovered components and newly emerging questions

    PubMed Central

    Hubbard, Katharine E.; Nishimura, Noriyuki; Hitomi, Kenichi; Getzoff, Elizabeth D.; Schroeder, Julian I.

    2010-01-01

    The plant hormone abscisic acid (ABA) regulates many key processes in plants, including seed germination and development and abiotic stress tolerance, particularly drought resistance. Understanding early events in ABA signal transduction has been a major goal of plant research. The recent identification of the PYRABACTIN (4-bromo-N-[pyridin-2-yl methyl]naphthalene-1-sulfonamide) RESISTANCE (PYR)/REGULATORY COMPONENT OF ABA RECEPTOR (RCAR) family of ABA receptors and their biochemical mode of action represents a major breakthrough in the field. The solving of PYR/RCAR structures provides a context for resolving mechanisms mediating ABA control of protein–protein interactions for downstream signaling. Recent studies show that a pathway based on PYR/RCAR ABA receptors, PROTEIN PHOSPHATASE 2Cs (PP2Cs), and SNF1-RELATED PROTEIN KINASE 2s (SnRK2s) forms the primary basis of an early ABA signaling module. This pathway interfaces with ion channels, transcription factors, and other targets, thus providing a mechanistic connection between the phytohormone and ABA-induced responses. This emerging PYR/RCAR–PP2C–SnRK2 model of ABA signal transduction is reviewed here, and provides an opportunity for testing novel hypotheses concerning ABA signaling. We address newly emerging questions, including the potential roles of different PYR/RCAR isoforms, and the significance of ABA-induced versus constitutive PYR/RCAR–PP2C interactions. We also consider how the PYR/RCAR–PP2C–SnRK2 pathway interfaces with ABA-dependent gene expression, ion channel regulation, and control of small molecule signaling. These exciting developments provide researchers with a framework through which early ABA signaling can be understood, and allow novel questions about the hormone response pathway and possible applications in stress resistance engineering of plants to be addressed. PMID:20713515

  7. [Expression and functional analyses of the Arabidopsis QUA1 gene in light signal transduction].

    PubMed

    Chen, Zhaojin; Ding, Chuanyu; Zheng, Yuan

    2016-05-01

    Plants not only use light as an energy source for photosynthesis, but also have to monitor the light quality and quantity input to execute appropriate physiological and developmental responses, such as cell differentiation, structural and functional changes, as well as the formation of tissues and organs. The process is referred to as photomorphogenesis. Arabidopsis QUA1 (QUASIMODO1), which functions in pectin synthesis, is identified as a member of glycosyltransferases. Previously, the hypocotyl elongation of the qua1-1 mutant was shown to be inhibited under dark conditions. In this study, we used the qua1-1/cry1 and qua1-1/phyB double mutants as the materials to study the function of the QUA1 gene in light signal transduction. The results showed that QUA1 not only participated in hypocotyl elongation under dark conditions, but also in blue light, red light and far red light conditions. In qua1-1 mutant seedlings, both the cell length of hypocotyl and the light-regulated gene expression were affected. Compared with cry1 and phyB mutants, qua1-1/cry1 and qua1-1/phyB double mutants had the shorter hypocotyl. Light-regulated gene expression was also affected in the double mutants. These data indicated that QUA1 might participate in the light signal transduction regulated by CRY1 and PHYB. Hence, the QUA1 gene may play multiple roles in light signal transduction by regulating the cell elongation and light-regulated gene expression. PMID:27232492

  8. [Expression and functional analyses of the Arabidopsis QUA1 gene in light signal transduction].

    PubMed

    Chen, Zhaojin; Ding, Chuanyu; Zheng, Yuan

    2016-05-01

    Plants not only use light as an energy source for photosynthesis, but also have to monitor the light quality and quantity input to execute appropriate physiological and developmental responses, such as cell differentiation, structural and functional changes, as well as the formation of tissues and organs. The process is referred to as photomorphogenesis. Arabidopsis QUA1 (QUASIMODO1), which functions in pectin synthesis, is identified as a member of glycosyltransferases. Previously, the hypocotyl elongation of the qua1-1 mutant was shown to be inhibited under dark conditions. In this study, we used the qua1-1/cry1 and qua1-1/phyB double mutants as the materials to study the function of the QUA1 gene in light signal transduction. The results showed that QUA1 not only participated in hypocotyl elongation under dark conditions, but also in blue light, red light and far red light conditions. In qua1-1 mutant seedlings, both the cell length of hypocotyl and the light-regulated gene expression were affected. Compared with cry1 and phyB mutants, qua1-1/cry1 and qua1-1/phyB double mutants had the shorter hypocotyl. Light-regulated gene expression was also affected in the double mutants. These data indicated that QUA1 might participate in the light signal transduction regulated by CRY1 and PHYB. Hence, the QUA1 gene may play multiple roles in light signal transduction by regulating the cell elongation and light-regulated gene expression.

  9. Plant gravitropic signal transduction: A network analysis leads to gene discovery

    NASA Astrophysics Data System (ADS)

    Wyatt, Sarah

    Gravity plays a fundamental role in plant growth and development. Although a significant body of research has helped define the events of gravity perception, the role of the plant growth regulator auxin, and the mechanisms resulting in the gravity response, the events of signal transduction, those that link the biophysical action of perception to a biochemical signal that results in auxin redistribution, those that regulate the gravitropic effects on plant growth, remain, for the most part, a “black box.” Using a cold affect, dubbed the gravity persistent signal (GPS) response, we developed a mutant screen to specifically identify components of the signal transduction pathway. Cloning of the GPS genes have identified new proteins involved in gravitropic signaling. We have further exploited the GPS response using a multi-faceted approach including gene expression microarrays, proteomics analysis, and bioinformatics analysis and continued mutant analysis to identified additional genes, physiological and biochemical processes. Gene expression data provided the foundation of a regulatory network for gravitropic signaling. Based on these gene expression data and related data sets/information from the literature/repositories, we constructed a gravitropic signaling network for Arabidopsis inflorescence stems. To generate the network, both a dynamic Bayesian network approach and a time-lagged correlation coefficient approach were used. The dynamic Bayesian network added existing information of protein-protein interaction while the time-lagged correlation coefficient allowed incorporation of temporal regulation and thus could incorporate the time-course metric from the data set. Thus the methods complemented each other and provided us with a more comprehensive evaluation of connections. Each method generated a list of possible interactions associated with a statistical significance value. The two networks were then overlaid to generate a more rigorous, intersected

  10. Structure-function relationships in the IL-17 receptor: Implications for signal transduction and therapy

    PubMed Central

    Shen, Fang; Gaffen, Sarah L.

    2008-01-01

    IL-17 is the defining cytokine of a newly-described “Th17” population that plays critical roles in mediating inflammation and autoimmunity. The IL-17/IL-17 receptor superfamily is the most recent class of cytokines and receptors to be described, and until recently very little was known about its function or molecular biology. However, in the last year important new insights into the composition and dynamics of the receptor complex and mechanisms of downstream signal transduction have been made, which will be reviewed here. PMID:18178098

  11. Do certain signal transduction mechanisms explain the comorbidity of epilepsy and mood disorders?

    PubMed

    Rocha, Luisa; Alonso-Vanegas, Mario; Orozco-Suárez, Sandra; Alcántara-González, David; Cruzblanca, Humberto; Castro, Elena

    2014-09-01

    It is well known that mood disorders are highly prevalent in patients with epilepsy. Although several studies have aimed to characterize alterations in different types of receptors associated with both disturbances, there is a lack of studies focused on identifying the causes of this comorbidity. Here, we described some changes at the biochemical level involving serotonin, dopamine, and γ-aminobutyric acid (GABA) receptors as well as signal transduction mechanisms that may explain the coexistence of both epilepsy and mood disorders. Finally, the identification of common pathophysiological mechanisms associated with receptor-receptor interaction (heterodimers) could allow designing new strategies for treatment of patients with epilepsy and comorbid mood disorders.

  12. A model for signal transduction during quorum sensing in Vibrio harveyi

    NASA Astrophysics Data System (ADS)

    Banik, Suman K.; Fenley, Andrew T.; Kulkarni, Rahul V.

    2009-12-01

    We present a framework for analyzing luminescence regulation during quorum sensing in the bioluminescent bacterium Vibrio harveyi. Using a simplified model for signal transduction in the quorum sensing pathway, we identify key dimensionless parameters that control the system's response. These parameters are estimated using experimental data on luminescence phenotypes for different mutant strains. The corresponding model predictions are consistent with results from other experiments which did not serve as input for determining model parameters. Furthermore, the proposed framework leads to novel testable predictions for luminescence phenotypes and for responses of the network to different perturbations.

  13. Smartphone Operated Signal Transduction by Ion Nanogating (STING) Amplifier for Nanopore Sensors: Design and Analytical Application

    PubMed Central

    Özel, Rıfat Emrah; Kahnemouyi, Sina; Fan, Hsinwen; Mak, Wai Han; Lohith, Akshar; Seger, Adam; Teodorescu, Mircea; Pourmand, Nader

    2016-01-01

    In this report, we demonstrated a handheld wireless voltage-clamp amplifier for current measurement of nanopore sensors. This amplifier interfaces a sensing probe and connects wirelessly with a computer or smartphone for the required stimulus input, data processing and storage. To test the proposed Signal Transduction by Ion Nanogating (STING) wireless amplifier, in the current study the system was tested with a nano-pH sensor to measure pH of standard buffer solutions and the performance was compared against the commercial voltage-clamp amplifier. To our best knowledge, STING amplifier is the first miniaturized wireless voltage-clamp platform operated with a customized smart-phone application (app).

  14. Signal transduction disturbance related to hepatocarcinogenesis in mouse by prolonged exposure to Nanjing drinking water.

    PubMed

    Zhang, Rui; Sun, Jie; Zhang, Yan; Cheng, Shupei; Zhang, Xiaowei

    2013-09-01

    Toxicogenomic approaches were used to investigate the potential hepatocarcinogenic effects on mice by oral exposure to Nanjing drinking water (NJDW). Changes in the hepatic transcriptome of 3 weeks male mice (Mus musculus) were monitored and dissected after oral exposure to NJDW for 90 days. No preneoplastic and neoplastic lesions were observed in the hepatic tissue by the end of NJDW exposure. However, total of 746 genes were changed transcriptionally. Thirty-one percent of differentially expressed genes (DEGs) were associated with the functional categories of cell cycle regulation, adhesion, growth, apoptosis, and signal transduction, which are closely implicated in tumorigenesis and progression. Interrogation of Kyoto Encyclopedia of Genes and Genomes revealed that 43 DEGs were mapped to several crucial signaling pathways implicated in the pathogenesis of hepatocellular carcinoma (HCC). In signal transduction network constructed via Genes2Networks software, Egfr, Akt1, Atf2, Ctnnb1, Hras, Mapk1, Smad2, and Ccnd1 were hubs. Direct gene-disease relationships obtained from Comparative Toxicogenomics Database and scientific literatures revealed that the hubs have direct mechanism or biomarker relationships with hepatocellular preneoplastic lesions or hepatocarcinogenesis. Therefore, prolonged intake of NJDW without employing any indoor water treatment strategy might predispose mouse to HCC. Furthermore, Egfr, Akt1, Ctnnb1, Hras, Mapk1, Smad2, and Ccnd1 were identified as promising biomarkers of the potential combined hepatocarcinogenicity.

  15. Target of Rapamycin Is a Key Player for Auxin Signaling Transduction in Arabidopsis

    PubMed Central

    Deng, Kexuan; Yu, Lihua; Zheng, Xianzhe; Zhang, Kang; Wang, Wanjing; Dong, Pan; Zhang, Jiankui; Ren, Maozhi

    2016-01-01

    Target of rapamycin (TOR), a master sensor for growth factors and nutrition availability in eukaryotic species, is a specific target protein of rapamycin. Rapamycin inhibits TOR kinase activity viaFK506 binding protein 12 kDa (FKBP12) in all examined heterotrophic eukaryotic organisms. In Arabidopsis, several independent studies have shown that AtFKBP12 is non-functional under aerobic condition, but one study suggests that AtFKBP12 is functional during anaerobic growth. However, the functions of AtFKBP12 have never been examined in parallel under aerobic and anaerobic growth conditions so far. To this end, we cloned the FKBP12 gene of humans, yeast, and Arabidopsis, respectively. Transgenic plants were generated, and pharmacological examinations were performed in parallel with Arabidopsis under aerobic and anaerobic conditions. ScFKBP12 conferred plants with the strongest sensitivity to rapamycin, followed by HsFKBP12, whereas AtFKBP12 failed to generate rapamycin sensitivity under aerobic condition. Upon submergence, yeast and human FKBP12 can significantly block cotyledon greening while Arabidopsis FKBP12 only retards plant growth in the presence of rapamycin, suggesting that hypoxia stress could partially restore the functions of AtFKBP12 to bridge the interaction between rapamycin and TOR. To further determine if communication between TOR and auxin signaling exists in plants, yeast FKBP12 was introduced into DR5::GUS homozygous plants. The transgenic plants DR5/BP12 were then treated with rapamycin or KU63794 (a new inhibitor of TOR). GUS staining showed that the auxin content of root tips decreased compared to the control. DR5/BP12 plants lost sensitivity to auxin after treatment with rapamycin. Auxin-defective phenotypes, including short primary roots, fewer lateral roots, and loss of gravitropism, occurred in DR5/BP12 plants when seedlings were treated with rapamycin+KU63794. This indicated that the combination of rapamycin and KU63794 can significantly

  16. Target of Rapamycin Is a Key Player for Auxin Signaling Transduction in Arabidopsis.

    PubMed

    Deng, Kexuan; Yu, Lihua; Zheng, Xianzhe; Zhang, Kang; Wang, Wanjing; Dong, Pan; Zhang, Jiankui; Ren, Maozhi

    2016-01-01

    Target of rapamycin (TOR), a master sensor for growth factors and nutrition availability in eukaryotic species, is a specific target protein of rapamycin. Rapamycin inhibits TOR kinase activity viaFK506 binding protein 12 kDa (FKBP12) in all examined heterotrophic eukaryotic organisms. In Arabidopsis, several independent studies have shown that AtFKBP12 is non-functional under aerobic condition, but one study suggests that AtFKBP12 is functional during anaerobic growth. However, the functions of AtFKBP12 have never been examined in parallel under aerobic and anaerobic growth conditions so far. To this end, we cloned the FKBP12 gene of humans, yeast, and Arabidopsis, respectively. Transgenic plants were generated, and pharmacological examinations were performed in parallel with Arabidopsis under aerobic and anaerobic conditions. ScFKBP12 conferred plants with the strongest sensitivity to rapamycin, followed by HsFKBP12, whereas AtFKBP12 failed to generate rapamycin sensitivity under aerobic condition. Upon submergence, yeast and human FKBP12 can significantly block cotyledon greening while Arabidopsis FKBP12 only retards plant growth in the presence of rapamycin, suggesting that hypoxia stress could partially restore the functions of AtFKBP12 to bridge the interaction between rapamycin and TOR. To further determine if communication between TOR and auxin signaling exists in plants, yeast FKBP12 was introduced into DR5::GUS homozygous plants. The transgenic plants DR5/BP12 were then treated with rapamycin or KU63794 (a new inhibitor of TOR). GUS staining showed that the auxin content of root tips decreased compared to the control. DR5/BP12 plants lost sensitivity to auxin after treatment with rapamycin. Auxin-defective phenotypes, including short primary roots, fewer lateral roots, and loss of gravitropism, occurred in DR5/BP12 plants when seedlings were treated with rapamycin+KU63794. This indicated that the combination of rapamycin and KU63794 can significantly

  17. Signal transduction events in aluminum-induced cell death in tomato suspension cells.

    PubMed

    Yakimova, Elena T; Kapchina-Toteva, Veneta M; Woltering, Ernst J

    2007-06-01

    In this study, some of the signal transduction events involved in AlCl(3)-induced cell death in tomato (Lycopersicon esculentum Mill.) suspension cells were elucidated. Cells treated with 100 microM AlCl(3) showed typical features of programmed cell death (PCD) such as nuclear and cytoplasmic condensation. Cell death was effectively inhibited by protease and human caspase inhibitors indicating a cell death execution mechanism with similarities to animal apoptosis. Cell death was suppressed by application of antoxidants and by inhibitors of phospholipase C (PLC), phospholipase D (PLD) and ethylene signalling pathways. The results suggest that low concentrations of heavy metal ions stimulate both PLC and PLD signalling pathways leading to the production of reactive oxygen species (ROS) and subsequent cell death executed by caspase-like proteases.

  18. Thermodynamic basis for redox regulation of the Yap1 signal transduction pathway.

    PubMed

    Mason, Jeremy T; Kim, Sung-Kun; Knaff, David B; Wood, Matthew J

    2006-11-14

    The Yap1 oxidative stress signal transduction pathway found in Saccharomyces cerevisiae is redox-regulated. We have examined the thermodynamic basis of the disulfide/dithiol couples that are involved in the regulation of this pathway. The oxidized form of the Yap1 redox domain (Yap1-RD) fragment, derived from the Yap1 transcription factor, contains two disulfide bonds, one between Cys303 and Cys598 and one between Cys310 and Cys629. Oxidation-reduction titrations reveal the presence of two separate two-electron redox couples in Yap1-RD, with redox midpoint potentials (E(m)) of -155 and -330 mV, respectively, at pH 7.0. We measured E(m) values of -275 and -265 mV for the two cytoplasmic S. cerevisiae thioredoxins, Trx1 and Trx2, respectively, both at pH 7.0. Last, we measured an E(m) value of -255 mV for the Cys36-Cys82 disulfide bond at pH 6.0 in the glutathione peroxidase-like enzyme, oxidant receptor protein (Orp1). We were unable to obtain satisfactory redox titration data for Orp1 at pH 7.0, but if the redox-active disulfide of Orp1 exhibits the -59 mV per pH unit dependence for E(m) typical of protein disulfides in this pH region, an E(m) value of -315 mV can be estimated for Orp1 at pH 7.0 by extrapolation. Together, these data suggest that, at physiological ratios of Trx(ox)/Trx(red), the reduction of both the E(m) = -315 mV disulfide of Orp1 and the E(m) = -330 mV disulfide of Yap1 by either Trx1 or Trx2 would be thermodynamically possible. PMID:17087494

  19. From stress to inflammation and major depressive disorder: a social signal transduction theory of depression.

    PubMed

    Slavich, George M; Irwin, Michael R

    2014-05-01

    Major life stressors, especially those involving interpersonal stress and social rejection, are among the strongest proximal risk factors for depression. In this review, we propose a biologically plausible, multilevel theory that describes neural, physiologic, molecular, and genomic mechanisms that link experiences of social-environmental stress with internal biological processes that drive depression pathogenesis. Central to this social signal transduction theory of depression is the hypothesis that experiences of social threat and adversity up-regulate components of the immune system involved in inflammation. The key mediators of this response, called proinflammatory cytokines, can in turn elicit profound changes in behavior, which include the initiation of depressive symptoms such as sad mood, anhedonia, fatigue, psychomotor retardation, and social-behavioral withdrawal. This highly conserved biological response to adversity is critical for survival during times of actual physical threat or injury. However, this response can also be activated by modern-day social, symbolic, or imagined threats, leading to an increasingly proinflammatory phenotype that may be a key phenomenon driving depression pathogenesis and recurrence, as well as the overlap of depression with several somatic conditions including asthma, rheumatoid arthritis, chronic pain, metabolic syndrome, cardiovascular disease, obesity, and neurodegeneration. Insights from this theory may thus shed light on several important questions including how depression develops, why it frequently recurs, why it is strongly predicted by early life stress, and why it often co-occurs with symptoms of anxiety and with certain physical disease conditions. This work may also suggest new opportunities for preventing and treating depression by targeting inflammation.

  20. From Stress to Inflammation and Major Depressive Disorder: A Social Signal Transduction Theory of Depression

    PubMed Central

    Slavich, George M.; Irwin, Michael R.

    2014-01-01

    Major life stressors, especially those involving interpersonal stress and social rejection, are among the strongest proximal risk factors for depression. In this review, we propose a biologically plausible, multilevel theory that describes neural, physiologic, molecular, and genomic mechanisms that link experiences of social-environmental stress with internal biological processes that drive depression pathogenesis. Central to this social signal transduction theory of depression is the hypothesis that experiences of social threat and adversity up-regulate components of the immune system involved in inflammation. The key mediators of this response, called proinflammatory cytokines, can in turn elicit profound changes in behavior, which include the initiation of depressive symptoms such as sad mood, anhedonia, fatigue, psychomotor retardation, and social-behavioral withdrawal. This highly conserved biological response to adversity is critical for survival during times of actual physical threat or injury. However, this response can also be activated by modern-day social, symbolic, or imagined threats, leading to an increasingly proinflammatory phenotype that may be a key phenomenon driving depression pathogenesis and recurrence, as well as the overlap of depression with several somatic conditions including asthma, rheumatoid arthritis, chronic pain, metabolic syndrome, cardiovascular disease, obesity, and neurodegeneration. Insights from this theory may thus shed light on several important questions including how depression develops, why it frequently recurs, why it is strongly predicted by early life stress, and why it often co-occurs with symptoms of anxiety and with certain physical disease conditions. This work may also suggest new opportunities for preventing and treating depression by targeting inflammation. PMID:24417575

  1. Signal transduction across cellular membranes can be mediated by coupling of the clustering of anchored proteins in both leaflets

    NASA Astrophysics Data System (ADS)

    Yue, Tongtao; Zhang, Xianren

    2012-01-01

    One key question in signal transduction is how the signal is relayed from the outer leaflet of a cellular membrane to the inner leaflet. Using a simulation model, a mechanism for the mediation of signal transduction is proposed here in which the coupling between membrane proteins in different leaflets can be achieved by the clustering of anchored proteins, without recruiting transmembrane proteins. Depending on the hydrophobic length of the anchored proteins, three coupling patterns, including face-to-face clustering, interdigitated clustering, and weak-coupled clustering, are observed in this work. This observation provides a possible explanation of how a particular downstream signaling pathway is selected.

  2. ELF3 Encodes a Circadian Clock–Regulated Nuclear Protein That Functions in an Arabidopsis PHYB Signal Transduction Pathway

    PubMed Central

    Liu, Xing Liang; Covington, Michael F.; Fankhauser, Christian; Chory, Joanne; Wagner, D. Ry

    2001-01-01

    Many aspects of plant development are regulated by photoreceptor function and the circadian clock. Loss-of-function mutations in the Arabidopsis EARLY FLOWERING 3 (ELF3) and PHYTOCHROME B (PHYB) genes cause early flowering and influence the activity of circadian clock–regulated processes. We demonstrate here that the relative abundance of the ELF3 protein, which is a novel nucleus-localized protein, displays circadian regulation that follows the pattern of circadian accumulation of ELF3 transcript. Furthermore, the ELF3 protein interacts with PHYB in the yeast two-hybrid assay and in vitro. Genetic analyses show that ELF3 requires PHYB function in early morphogenesis but not for the regulation of flowering time. This suggests that ELF3 is a component of a PHYB signaling complex that controls early events in plant development but that ELF3 and PHYB control flowering via independent signal transduction pathways. PMID:11402161

  3. Azelastine hydrochloride (Azeptin) inhibits peplomycin (PLM)-induced pulmonary fibrosis by contradicting the up-regulation of signal transduction.

    PubMed

    Yoneda, K; Yamamoto, T; Ueta, E; Osaki, T

    1997-10-01

    Inhibition of peplomycin (PLM)-induced pulmonary fibrosis by azelastine hydrochloride (Azeptin) was examined using ICR mice, and the effects of both drugs on signal transduction were investigated. Microscopically, Azeptin (a total of 56 mg/kg for 28 days) suppressed pulmonary fibrosis in mice which received an i.p. injection of a total of 60 or 75 mg/kg PLM. In parallel with the microscopic findings, smaller amounts of collagen were synthesized in the lungs of Azeptin-injected mice. PLM enhanced the expression of interleukin-1 beta- and transforming growth factor-beta-mRNA in lungs. In contrast, Azeptin suppressed the expression. Compatible with these in vivo results, Azeptin and PLM contradictively regulated protein tyrosine phosphorylation and c-myc mRNA expression in human gingival and mouse pulmonary fibroblasts. In addition, NF-kappa B was activated by fibroblast treatment with 5 micrograms/ml PLM for 1 h, but intranuclear NF-kappa B was decreased by cell treatment with 10(-5) M Azeptin. From these results, it is concluded that Azeptin inhibits PLM-induced pulmonary fibrosis by antagonizing the up-regulation of signal transduction.

  4. Alpha-1, alpha-2, and beta adrenergic signal transduction in cultured uterine myocytes.

    PubMed

    Phillippe, M; Saunders, T; Bangalore, S

    1990-04-01

    The following studies were undertaken to develop a cultured uterine myocyte model which would allow further clarification of the adrenergic signal transduction mechanisms utilized by these myocytes. After mechanical removal of the endometrium, rabbit uterine myocytes were isolated by an overnight enzymatic disaggregation using collagenase and DNase I. The isolated myocytes were maintained in culture in 75-cm2 flasks containing Waymouth's MB 751/1 medium-10% fetal bovine serum along with 10(-8) M estradiol, penicillin, streptomycin, and Fungizone. The phase contrast and electron micrographic appearance of these cells was consistent with that previously reported for smooth muscle myocytes in culture. Immunocytochemical studies utilizing monoclonal anti-alpha-smooth muscle actin antibodies confirmed the presence of smooth muscle actin in these cultured myocytes. Western blot studies similarly confirmed the presence of alpha-smooth muscle actin in rabbit myometrial tissue and the cultured myocytes, both the primary and F1 generation. After prelabeling the myocytes with [3H]inositol, adrenergic stimulation experiments demonstrated alpha-1 receptor mediated stimulation of inositol phosphates. Beta receptor stimulation experiments confirmed cAMP production in these cultured myocytes, and the ability of clonidine, an alpha-2 agonist, to inhibit forskolin stimulated cAMP production confirmed the presence of functional alpha-2 adrenergic receptors in these myocytes. In conclusion, these cultured rabbit uterine myocytes have provided an in vitro model which can be utilized to further clarify the adrenergic receptor signal transduction mechanisms in genital tract smooth muscle.

  5. Mechanism of Poly(A) Signal Transduction to RNA Polymerase II In Vitro

    PubMed Central

    Tran, Dong P.; Kim, Steven J.; Park, Noh Jin; Jew, Tiffany M.; Martinson, Harold G.

    2001-01-01

    Termination of transcription by RNA polymerase II usually requires the presence of a functional poly(A) site. How the poly(A) site signals its presence to the polymerase is unknown. All models assume that the signal is generated after the poly(A) site has been extruded from the polymerase, but this has never been tested experimentally. It is also widely accepted that a “pause” element in the DNA stops the polymerase and that cleavage at the poly(A) site then signals termination. These ideas also have never been tested. The lack of any direct tests of the poly(A) signaling mechanism reflects a lack of success in reproducing the poly(A) signaling phenomenon in vitro. Here we describe a cell-free transcription elongation assay that faithfully recapitulates poly(A) signaling in a crude nuclear extract. The assay requires the use of citrate, an inhibitor of RNA polymerase II carboxyl-terminal domain phosphorylation. Using this assay we show the following. (i) Wild-type but not mutant poly(A) signals instruct the polymerase to stop transcription on downstream DNA in a manner that parallels true transcription termination in vivo. (ii) Transcription stops without the need of downstream elements in the DNA. (iii) cis-antisense inhibition blocks signal transduction, indicating that the signal to stop transcription is generated following extrusion of the poly(A) site from the polymerase. (iv) Signaling can be uncoupled from processing, demonstrating that signaling does not require cleavage at the poly(A) site. PMID:11585929

  6. Gamma Interferon Augments Macrophage Activation by Lipopolysaccharide by Two Distinct Mechanisms, at the Signal Transduction Level and via an Autocrine Mechanism Involving Tumor Necrosis Factor Alpha and Interleukin-1

    PubMed Central

    Held, Thomas K.; Weihua, Xiao; Yuan, Liang; Kalvakolanu, Dhananjaya V.; Cross, Alan S.

    1999-01-01

    When given in the presence of gamma interferon (IFN-γ), otherwise nontoxic doses of lipopolysaccharide (LPS or endotoxin) become highly lethal for mice. The mechanisms of this synergistic toxicity are not known. We considered the possibility that an interaction between the LPS-induced NF-κB and IFN-γ-induced JAK-STAT pathways at the pretranscriptional level may enhance the LPS-induced signals. To test this hypothesis, we incubated murine macrophage RAW 264.7 cells with IFN-γ for 2 h before addition of different doses of LPS. Consistent with the synergistic induction of inducible nitric oxide synthase mRNA and nitric oxide production by a combination of LPS and IFN-γ, IFN-γ strongly augmented LPS-induced NF-κB activation and accelerated the binding of NF-κB to DNA to as early as 5 min. In agreement with this, IFN-γ pretreatment promoted rapid degradation of IκB-α but not that of IκB-β. Inhibition of protein synthesis during IFN-γ treatment suppressed LPS-initiated NF-κB binding. A rapidly induced protein appeared to be involved in IFN-γ priming. Preincubation of cells with antibodies to tumor necrosis factor alpha or the interleukin-1 receptor partially reduced the priming effect of IFN-γ. In a complementary manner, LPS enhanced the activation of signal-transducing activator of transcription 1 by IFN-γ. These data suggest novel mechanisms for the synergy between IFN-γ and LPS by which they cross-regulate the signal-transducing molecules. Through this mechanism, IFN-γ may transform a given dose of LPS into a lethal stimulus capable of causing sepsis. It may also serve a beneficial purpose by enabling the host to respond quickly to relatively low doses of LPS and thereby activating antibacterial defenses. PMID:9864217

  7. Involvement of the second messenger cAMP in gravity-signal transduction in physarum

    NASA Astrophysics Data System (ADS)

    Block, I.; Rabien, H.; Ivanova, K.

    The aim of the investigation was to clarify, whether cellular signal processing following graviperception involves second messenger pathways. The test object was a most gravisensitive free-living ameboid cell, the myxomycete (acellular slime mold) Physarum polycephalum. It was demonstrated that the motor response is related to acceleration-dependent changes in the levels of the cellular second messenger cyclic adenosine monophosphate (cAMP). Rotating Physarum plasmodia in the gravity field of the Earth about a horizontal axis increased their cAMP concentration. Depriving the cells for a few days of the acceleration stimulus (near weightlessness in a space experiment on STS-69) slightly lowered plasmodial cAMP levels. Thus, the results provide first indications that the acceleration-stimulus signal transduction chain of Physarum uses an ubiquitous second messenger pathway.

  8. A nexus for cellular homeostasis: the interplay between metabolic and signal transduction pathways.

    PubMed

    Gomes, Ana P; Blenis, John

    2015-08-01

    In multicellular organisms, individual cells have evolved to sense external and internal cues in order to maintain cellular homeostasis and survive under different environmental conditions. Cells efficiently adjust their metabolism to reflect the abundance of nutrients, energy and growth factors. The ability to rewire cellular metabolism between anabolic and catabolic processes is crucial for cells to thrive. Thus, cells have developed, through evolution, metabolic networks that are highly plastic and tightly regulated to meet the requirements necessary to maintain cellular homeostasis. The plasticity of these cellular systems is tightly regulated by complex signaling networks that integrate the intracellular and extracellular information. The coordination of signal transduction and metabolic pathways is essential in maintaining a healthy and rapidly responsive cellular state.

  9. Genomic Targets and Features of BarA-UvrY (-SirA) Signal Transduction Systems

    PubMed Central

    Zere, Tesfalem R.; Vakulskas, Christopher A.; Leng, Yuanyuan; Pannuri, Archana; Potts, Anastasia H.; Dias, Raquel; Tang, Dongjie; Kolaczkowski, Bryan; Georgellis, Dimitris; Ahmer, Brian M. M.; Romeo, Tony

    2015-01-01

    The two-component signal transduction system BarA-UvrY of Escherichia coli and its orthologs globally regulate metabolism, motility, biofilm formation, stress resistance, virulence of pathogens and quorum sensing by activating the transcription of genes for regulatory sRNAs, e.g. CsrB and CsrC in E. coli. These sRNAs act by sequestering the RNA binding protein CsrA (RsmA) away from lower affinity mRNA targets. In this study, we used ChIP-exo to identify, at single nucleotide resolution, genomic sites for UvrY (SirA) binding in E. coli and Salmonella enterica. The csrB and csrC genes were the strongest targets of crosslinking, which required UvrY phosphorylation by the BarA sensor kinase. Crosslinking occurred at two sites, an inverted repeat sequence far upstream of the promoter and a site near the -35 sequence. DNAse I footprinting revealed specific binding of UvrY in vitro only to the upstream site, indicative of additional binding requirements and/or indirect binding to the downstream site. Additional genes, including cspA, encoding the cold-shock RNA-binding protein CspA, showed weaker crosslinking and modest or negligible regulation by UvrY. We conclude that the global effects of UvrY/SirA on gene expression are primarily mediated by activating csrB and csrC transcription. We also used in vivo crosslinking and other experimental approaches to reveal new features of csrB/csrC regulation by the DeaD and SrmB RNA helicases, IHF, ppGpp and DksA. Finally, the phylogenetic distribution of BarA-UvrY was analyzed and found to be uniquely characteristic of γ-Proteobacteria and strongly anti-correlated with fliW, which encodes a protein that binds to CsrA and antagonizes its activity in Bacillus subtilis. We propose that BarA-UvrY and orthologous TCS transcribe sRNA antagonists of CsrA throughout the γ-Proteobacteria, but rarely or never perform this function in other species. PMID:26673755

  10. The Sulfiredoxin-Peroxiredoxin (Srx-Prx) Axis in Cell Signal Transduction and Cancer Development

    PubMed Central

    Mishra, Murli; Jiang, Hong; Wu, Lisha; Chawsheen, Hedy A; Wei, Qiou

    2015-01-01

    Redox signaling is a critical component of cell signaling pathways that is involved in regulation of cell growth, metabolism, hormone signaling, immune regulation and variety of other physiological functions. Peroxiredoxin (Prx) is a family of thiol-based peroxidases that acts as a regulator of redox signaling. Members of Prx family can act as antioxidants and chaperone. Sulfiredoxin (Srx) is an antioxidant protein that exclusively reduces over-oxidized typical 2-Cys Prx. Srx have different affinities for individual Prx and it also catalyzes deglutathionylation of variety of substrates. Individual components of Srx-Prx system play critical roles in carcinogenesis by modulating cell signaling pathway involved in cell proliferation, migration and metastasis. Expression levels of individual components of Srx-Prx axis has been correlated with patient survival outcome in multiple cancer types. This review will summarize the molecular basis of differences in affinity of Srx for individual Prx and the role of individual components of Srx-Prx system in tumor progression and metastasis. This enhanced understanding of molecular aspects of Srx-Prx interaction and its role in cell signal transduction will help in defining Srx-Prx system as a future therapeutic target in human cancer. PMID:26170166

  11. The Roles of Peroxiredoxin and Thioredoxin in Hydrogen Peroxide Sensing and in Signal Transduction

    PubMed Central

    Netto, Luis E. S.; Antunes, Fernando

    2016-01-01

    A challenge in the redox field is the elucidation of the molecular mechanisms, by which H2O2 mediates signal transduction in cells. This is relevant since redox pathways are disturbed in some pathologies. The transcription factor OxyR is the H2O2 sensor in bacteria, whereas Cys-based peroxidases are involved in the perception of this oxidant in eukaryotic cells. Three possible mechanisms may be involved in H2O2 signaling that are not mutually exclusive. In the simplest pathway, H2O2 signals through direct oxidation of the signaling protein, such as a phosphatase or a transcription factor. Although signaling proteins are frequently observed in the oxidized state in biological systems, in most cases their direct oxidation by H2O2 is too slow (101 M−1s−1 range) to outcompete Cys-based peroxidases and glutathione. In some particular cellular compartments (such as vicinity of NADPH oxidases), it is possible that a signaling protein faces extremely high H2O2 concentrations, making the direct oxidation feasible. Alternatively, high H2O2 levels can hyperoxidize peroxiredoxins leading to local building up of H2O2 that then could oxidize a signaling protein (floodgate hypothesis). In a second model, H2O2 oxidizes Cys-based peroxidases that then through thiol-disulfide reshuffling would transmit the oxidized equivalents to the signaling protein. The third model of signaling is centered on the reducing substrate of Cys-based peroxidases that in most cases is thioredoxin. Is this model, peroxiredoxins would signal by modulating the thioredoxin redox status. More kinetic data is required to allow the identification of the complex network of thiol switches. PMID:26813662

  12. Epidermal Growth Factor Receptor in Glioma: Signal Transduction, Neuropathology, Imaging, and Radioresistance1

    PubMed Central

    Hatanpaa, Kimmo J; Burma, Sandeep; Zhao, Dawen; Habib, Amyn A

    2010-01-01

    Aberrant epidermal growth factor receptor (EGFR) signaling is common in cancer. Increased expression of wild type and mutant EGFR is a widespread feature of diverse types of cancer. EGFR signaling in cancer has been the focus of intense investigation for decades primarily for two reasons. First, aberrant EGFR signaling is likely to play an important role in the pathogenesis of cancer, and therefore, the mechanisms of EGFR-mediated oncogenic signaling are of interest. Second, the EGFR signaling system is an attractive target for therapeutic intervention. EGFR gene amplification and overexpression are a particularly striking feature of glioblastoma (GBM), observed in approximately 40% of tumors. GBM is the most common primary malignant tumor of the central nervous system in adults. In approximately 50% of tumors with EGFR amplification, a specific EGFR mutant (EGFRvIII, also known as EGFR type III, de2-7, ΔEGFR) can be detected. This mutant is highly oncogenic and is generated from a deletion of exons 2 to 7 of the EGFR gene, which results in an in-frame deletion of 267 amino acids from the extracellular domain of the receptor. EGFRvIII is unable to bind ligand, and it signals constitutively. Although EGFRvIII has the same signaling domain as the wild type receptor, it seems to generate a distinct set of downstream signals that may contribute to an increased tumorigenicity. In this review, we discuss recent progress in key aspects of EGFR signaling in GBM, focusing on neuropathology, signal transduction, imaging of the EGFR, and the role of the EGFR in mediating resistance to radiation therapy in GBM. PMID:20824044

  13. Deuterohemin-AlaHisLys mitigates the symptoms of rats with non-insulin dependent diabetes mellitus by scavenging reactive oxygen species and activating the PI3-K/AKT signal transduction pathway.

    PubMed

    Lei, Liyan; Zhang, Guangji; Li, Pengfei; Zhang, Yuan; Guo, Youming; Zhang, Wenqi; Zhang, Wenbo; Hu, Bing; Wang, Liping

    2014-09-01

    Damage to pancreatic β-cells plays an important role in the development of type 2 diabetes, and oxidative stress is a likely contributor. In the present study, we investigated the effect of deuterohemin-AlaHisLys (DhHP-3), a microperoxidase-11 mimic, on rats with non-insulin dependent diabetes mellitus and examined the action mechanisms of DhHP-3. The induced hyperglycemia, glucose intolerance, and insulin resistance in diabetic rats were associated with increased oxidative stress and damage to pancreatic islets. DhHP-3 (3 mg/kg) ameliorated hyperglycemia and insulin resistance, protected pancreas islet, decreased the content of malondialdehyde, and increased the activity of superoxide dismutase in plasma and pancreatic tissue by reducing ROS levels. Furthermore, DhHP-3 stimulated the proliferation of INS-1 cells and inhibited apoptosis by activating the phosphatidylinositol 3-kinase/protein kinase B (PI3-K/AKT) signaling pathway. Our results demonstrated for the first time that DhHP-3 decreased blood glucose level in rats with non-insulin dependent diabetes mellitus, scavenged reactive oxygen species, activated the PI3-K/AKT signaling pathway, and protected pancreatic β-cells against apoptosis.

  14. Epidermal Growth Factor Receptor Is a Critical Mediator of Ultraviolet B Irradiation-Induced Signal Transduction in Immortalized Human Keratinocyte HaCaT Cells

    PubMed Central

    Xu, Yiru; Voorhees, John J.; Fisher, Gary J.

    2006-01-01

    Epidermal growth factor receptor (EGFR) is a critical mediator of several types of epithelial cancers. Skin cancer arising from exposure to ultraviolet B irradiation (UVB) from the sun is a prominent form of human cancer. Recent data indicate that in addition to cognate ligands, EGFR is activated by UVB irradiation. We used pharmacological and genetic approaches to investigate the function of EGFR in mediating UVB-induced signal transduction in human skin keratinocyte HaCaT cells. Pharmacological inhibition of EGFR tyrosine kinase significantly inhibited UVB-mediated induction of ERK, p38, and JNK MAP kinases, and their effectors, transcription factors c-Fos and c-Jun. Inhibition of UVB activation of EGFR also suppressed activation of AKT-, PKC-, and PKA-dependent signal transduction pathways. B82 mouse L cells devoid of EGFR were used to further investigate EGFR dependence of UVB-induced signal transduction. UVB failed to induce ERK, and JNK activation was reduced 60% in B82 cells compared to B82K+ cells, which express EGFR. In addition, UVB induced both c-Fos and c-Jun proteins in B82K+ cells, whereas neither were induced in B82 cells. Taken together, these data demonstrate that EGFR is required for UVB-mediated induction of multiple signaling pathways that are known to mediate tumor formation in skin. PMID:16936259

  15. Overexpression of PGC-1α Influences Mitochondrial Signal Transduction of Dopaminergic Neurons.

    PubMed

    Ye, Qinyong; Huang, Wanling; Li, Dongzhu; Si, Erwang; Wang, Juhua; Wang, Yingqing; Chen, Chun; Chen, Xiaochun

    2016-08-01

    Parkinson's disease (PD) is a common neurodegenerative disease in the elderly. Mitochondrial dysfunction plays an important role in the pathogenesis of PD. Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) is a powerful transcription factor, interacting with multiple transcription factors and widely involving in the regulation of mitochondrial biogenesis, oxidative stress, and other processes. The present study investigated the neuroprotective effects and signal transduction mechanisms of the overexpression of PGC-1α on N-methyl-4-phenylpyridinium ion (MPP(+))-induced mitochondrial damage in SH-SY5Y cell, establishing the cell model of overexpression of PGC-1α and the cell model of PD by using adenoviral vectors and MPP(+). 3-(4,5-Dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide thiazolyl blue (MTT) assay was used to investigate the effects of MPP(+) and adenovirus on the cell viability of SH-SY5Y cells and the cell viability of experimental groups. Western blot and real-time PCR analysis were used to detect the expression of PGC-1α. Flow cytometry and ELISA were used to detect mitochondrial membrane potential and the level of cytochrome C, respectively. The level of intracellular ATP and H2O2 was measured by multifunctional fluorescence microplate. Western blot analysis and real-time PCR were used to observe the expression of estrogen-related receptor α (ERRα), peroxisome proliferator-activated receptor γ (PPARγ), nuclear respiratory factor (NRF)-1, and NRF-2. Confocal fluorescence analysis was used to observe subcellular localization of PGC-1α in SH-SY5Y cells under the intervention of MPP(+). The expression of PGC-1α messenger RNA and protein significantly increased in Adv-PGC-1α + GFP groups, compared with the control and Adv-GFP groups (P < 0.01). The overexpression of PGC-1α could increase mitochondrial membrane potential, reduce the release of mitochondrial cytochrome C, inhibit H2O2 production, and improve the

  16. Non Linear Programming (NLP) formulation for quantitative modeling of protein signal transduction pathways.

    PubMed

    Mitsos, Alexander; Melas, Ioannis N; Morris, Melody K; Saez-Rodriguez, Julio; Lauffenburger, Douglas A; Alexopoulos, Leonidas G

    2012-01-01

    Modeling of signal transduction pathways plays a major role in understanding cells' function and predicting cellular response. Mathematical formalisms based on a logic formalism are relatively simple but can describe how signals propagate from one protein to the next and have led to the construction of models that simulate the cells response to environmental or other perturbations. Constrained fuzzy logic was recently introduced to train models to cell specific data to result in quantitative pathway models of the specific cellular behavior. There are two major issues in this pathway optimization: i) excessive CPU time requirements and ii) loosely constrained optimization problem due to lack of data with respect to large signaling pathways. Herein, we address both issues: the former by reformulating the pathway optimization as a regular nonlinear optimization problem; and the latter by enhanced algorithms to pre/post-process the signaling network to remove parts that cannot be identified given the experimental conditions. As a case study, we tackle the construction of cell type specific pathways in normal and transformed hepatocytes using medium and large-scale functional phosphoproteomic datasets. The proposed Non Linear Programming (NLP) formulation allows for fast optimization of signaling topologies by combining the versatile nature of logic modeling with state of the art optimization algorithms.

  17. A dual receptor crosstalk model of G-protein-coupled signal transduction.

    PubMed

    Flaherty, Patrick; Radhakrishnan, Mala L; Dinh, Tuan; Rebres, Robert A; Roach, Tamara I; Jordan, Michael I; Arkin, Adam P

    2008-09-26

    Macrophage cells that are stimulated by two different ligands that bind to G-protein-coupled receptors (GPCRs) usually respond as if the stimulus effects are additive, but for a minority of ligand combinations the response is synergistic. The G-protein-coupled receptor system integrates signaling cues from the environment to actuate cell morphology, gene expression, ion homeostasis, and other physiological states. We analyze the effects of the two signaling molecules complement factors 5a (C5a) and uridine diphosphate (UDP) on the intracellular second messenger calcium to elucidate the principles that govern the processing of multiple signals by GPCRs. We have developed a formal hypothesis, in the form of a kinetic model, for the mechanism of action of this GPCR signal transduction system using data obtained from RAW264.7 macrophage cells. Bayesian statistical methods are employed to represent uncertainty in both data and model parameters and formally tie the model to experimental data. When the model is also used as a tool in the design of experiments, it predicts a synergistic region in the calcium peak height dose response that results when cells are simultaneously stimulated by C5a and UDP. An analysis of the model reveals a potential mechanism for crosstalk between the Galphai-coupled C5a receptor and the Galphaq-coupled UDP receptor signaling systems that results in synergistic calcium release.

  18. Pravastatin Prevents Aortic Atherosclerosis via Modulation of Signal Transduction and Activation of Transcription 3 (STAT3) to Attenuate Interleukin-6 (IL-6) Action in ApoE Knockout Mice

    PubMed Central

    Zhou, Xiaoxu; Li, Dan; Yan, Wei; Li, Weimin

    2008-01-01

    The purpose of this study was to determine whether pravastatin’s prevention of aortic atherosclerosis via attenuation of IL-6 action depends on modulation of STAT3 activity. Male apoE knockout (apoE-/-) mice fed on a diet containing 1.25% cholesterol (wt/wt) were divided into pravastatin group provided with pravastatin (80 mg kg-1 per day) and atherosclerosis group. After eight weeks, pravastatin significantly prevented atherosclerotic lesion and reduced levels of IL-6 in serum and lesion, and significantly decreased expressions of phosphorylated STAT3 (pSTAT3) and increased suppressor of cytokine signaling 3 (SOCS3) expressions in lesions. Our results suggested that pravastatin’s aortic atherosclerosis preventing action via attenuation of IL-6 action may partially depend on modulation of STAT3 activity. PMID:19330073

  19. Opposing effects of bile acids deoxycholic acid and ursodeoxycholic acid on signal transduction pathways in oesophageal cancer cells.

    PubMed

    Abdel-Latif, Mohamed M; Inoue, Hiroyasu; Reynolds, John V

    2016-09-01

    Ursodeoxycholic acid (UDCA) was reported to reduce bile acid toxicity, but the mechanisms underlying its cytoprotective effects are not fully understood. The aim of the present study was to examine the effects of UDCA on the modulation of deoxycholic acid (DCA)-induced signal transduction in oesophageal cancer cells. Nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) activity was assessed using a gel shift assay. NF-κB activation and translocation was performed using an ELISA-based assay and immunofluorescence analysis. COX-2 expression was analysed by western blotting and COX-2 promoter activity was assessed by luciferase assay. DCA induced NF-κB and AP-1 DNA-binding activities in SKGT-4 and OE33 cells. UDCA pretreatment inhibited DCA-induced NF-κB and AP-1 activation and NF-κB translocation. This inhibitory effect was coupled with a blockade of IκB-α degradation and inhibition of phosphorylation of IKK-α/β and ERK1/2. Moreover, UDCA pretreatment inhibited COX-2 upregulation. Using transient transfection of the COX-2 promoter, UDCA pretreatment abrogated DCA-induced COX-2 promoter activation. In addition, UDCA protected oesophageal cells from the apoptotic effects of deoxycholate. Our findings indicate that UDCA inhibits DCA-induced signalling pathways in oesophageal cancer cells. These data indicate a possible mechanistic role for the chemopreventive actions of UDCA in oesophageal carcinogenesis.

  20. The α,α-Difluorinated Phosphonate L-pSer-Analogue: An Accessible Chemical Tool for Studying Kinase-Dependent Signal Transduction in Vitro, and In Living Cells

    PubMed Central

    Panigrahi, Kaushik; Eggen, MariJean; Maeng, Jun-Ho; Shen, Quanrong; Berkowitz, David B.

    2009-01-01

    SUMMARY This overview focuses on the (α,α-difluoromethylene)phosphonate mimic of phosphoserine (pCF2Ser) and its application to the study of kinase-mediated signal transduction – pathways of great interest to drug development. The most versatile modes of access to these chemical biological tools are discussed, organized by method of PCF2-C bond. The pCF2-Ser mimic may be site-specifically incorporated into peptides (SPPS) and proteins (expressed protein ligation). This isopolar, dianionic pSer mimic results in a “constitutive phosphorylation” phenotype, and is seen to support native protein-protein interactions that depend upon serine phosphorylation. Signal transduction pathways studied with this chemical biological approach include the regulation of p53 tumor suppressor protein activity, and of melatonin production. Given these successes, the future is bright for the use of such “teflon phospho-amino acid mimics” to map kinase-based signaling pathways. PMID:19778720

  1. Further evidence supporting a role for gs signal transduction in severe malaria pathogenesis.

    PubMed

    Auburn, Sarah; Fry, Andrew E; Clark, Taane G; Campino, Susana; Diakite, Mahamadou; Green, Angela; Richardson, Anna; Jallow, Muminatou; Sisay-Joof, Fatou; Pinder, Margaret; Molyneux, Malcolm E; Taylor, Terrie E; Haldar, Kasturi; Rockett, Kirk A; Kwiatkowski, Dominic P

    2010-04-01

    With the functional demonstration of a role in erythrocyte invasion by Plasmodium falciparum parasites, implications in the aetiology of common conditions that prevail in individuals of African origin, and a wealth of pharmacological knowledge, the stimulatory G protein (Gs) signal transduction pathway presents an exciting target for anti-malarial drug intervention. Having previously demonstrated a role for the G-alpha-s gene, GNAS, in severe malaria disease, we sought to identify other important components of the Gs pathway. Using meta-analysis across case-control and family trio (affected child and parental controls) studies of severe malaria from The Gambia and Malawi, we sought evidence of association in six Gs pathway candidate genes: adenosine receptor 2A (ADORA2A) and 2B (ADORA2B), beta-adrenergic receptor kinase 1 (ADRBK1), adenylyl cyclase 9 (ADCY9), G protein beta subunit 3 (GNB3), and regulator of G protein signalling 2 (RGS2). Our study amassed a total of 2278 cases and 2364 controls. Allele-based models of association were investigated in all genes, and genotype and haplotype-based models were investigated where significant allelic associations were identified. Although no significant associations were observed in the other genes, several were identified in ADORA2A. The most significant association was observed at the rs9624472 locus, where the G allele (approximately 20% frequency) appeared to confer enhanced risk to severe malaria [OR = 1.22 (1.09-1.37); P = 0.001]. Further investigation of the ADORA2A gene region is required to validate the associations identified here, and to identify and functionally characterize the responsible causal variant(s). Our results provide further evidence supporting a role of the Gs signal transduction pathway in the regulation of severe malaria, and request further exploration of this pathway in future studies.

  2. Association between insulin resistance and impairment of FGF21 signal transduction in skeletal muscles.

    PubMed

    Jeon, Ja Young; Choi, Sung-E; Ha, Eun Suk; Kim, Tae Ho; Jung, Jong Gab; Han, Seung Jin; Kim, Hae Jin; Kim, Dae Jung; Kang, Yup; Lee, Kwan-Woo

    2016-07-01

    Fibroblast growth factor (FGF) 21, was identified as a potent metabolic regulator of glucose and lipid metabolism. We investigated whether the levels and signalings of FGF21 changed in the skeletal muscle of type 2 diabetes mellitus (T2DM) patients, participants with impaired glucose tolerance (IGT), human skeletal muscle myotubes (HSMMs) under insulin-resistant conditions, and mice with diet-induced obesity (DIO). A percutaneous biopsy sample of the vastus lateralis muscle of T2DM patients, IGT subjects, and participants with normal glucose tolerance was obtained and the levels and signalings of FGF21 were assessed. We determined whether the expression and signalings of FGF21 in HSMMs altered according to palmitate concentrations and exposure time. Also, we confirmed whether changes of FGF21 signal transduction resulted in the alteration of FGF21 functions. DIO mice were treated intravenously with recombinant FGF21, and the levels and signalings of FGF21 were assessed in their soleus muscles. We checked whether or not FGF21 played a role in the gene transcription related to lipid oxidation. Levels of FGF21 increased, whereas levels of phosphorylated FGF receptor (p-FGFR), phosphorylated FGFR substrates 2α (p-FRS2α), and phosphorylated extracellular signal-regulated kinases (p-ERK) decreased in the skeletal muscle of both T2DM patients and IGT subjects. In vitro, palmitate increased the levels of FGF21 and significantly reduced the levels of β-klotho, p-FGFR, p-FRS2α, and p-ERK1/2 in HSMMs exposed to palmitate. Palmitate also decreased glucose uptake and glycogen contents of FGF21. Consistently, the levels of FGF21 were significantly higher and the levels of β-klotho and p-FGFR were lower in the DIO mice than in normal lean mice. The levels of FGF21 increased but its signal transduction and actions were impaired in skeletal muscles of T2DM patients, IGT subjects, in insulin-resistant HSMMs, and DIO mice.

  3. Systems Perturbation Analysis of a Large-Scale Signal Transduction Model Reveals Potentially Influential Candidates for Cancer Therapeutics

    PubMed Central

    Puniya, Bhanwar Lal; Allen, Laura; Hochfelder, Colleen; Majumder, Mahbubul; Helikar, Tomáš

    2016-01-01

    Dysregulation in signal transduction pathways can lead to a variety of complex disorders, including cancer. Computational approaches such as network analysis are important tools to understand system dynamics as well as to identify critical components that could be further explored as therapeutic targets. Here, we performed perturbation analysis of a large-scale signal transduction model in extracellular environments that stimulate cell death, growth, motility, and quiescence. Each of the model’s components was perturbed under both loss-of-function and gain-of-function mutations. Using 1,300 simulations under both types of perturbations across various extracellular conditions, we identified the most and least influential components based on the magnitude of their influence on the rest of the system. Based on the premise that the most influential components might serve as better drug targets, we characterized them for biological functions, housekeeping genes, essential genes, and druggable proteins. The most influential components under all environmental conditions were enriched with several biological processes. The inositol pathway was found as most influential under inactivating perturbations, whereas the kinase and small lung cancer pathways were identified as the most influential under activating perturbations. The most influential components were enriched with essential genes and druggable proteins. Moreover, known cancer drug targets were also classified in influential components based on the affected components in the network. Additionally, the systemic perturbation analysis of the model revealed a network motif of most influential components which affect each other. Furthermore, our analysis predicted novel combinations of cancer drug targets with various effects on other most influential components. We found that the combinatorial perturbation consisting of PI3K inactivation and overactivation of IP3R1 can lead to increased activity levels of apoptosis

  4. Systems Perturbation Analysis of a Large-Scale Signal Transduction Model Reveals Potentially Influential Candidates for Cancer Therapeutics.

    PubMed

    Puniya, Bhanwar Lal; Allen, Laura; Hochfelder, Colleen; Majumder, Mahbubul; Helikar, Tomáš

    2016-01-01

    Dysregulation in signal transduction pathways can lead to a variety of complex disorders, including cancer. Computational approaches such as network analysis are important tools to understand system dynamics as well as to identify critical components that could be further explored as therapeutic targets. Here, we performed perturbation analysis of a large-scale signal transduction model in extracellular environments that stimulate cell death, growth, motility, and quiescence. Each of the model's components was perturbed under both loss-of-function and gain-of-function mutations. Using 1,300 simulations under both types of perturbations across various extracellular conditions, we identified the most and least influential components based on the magnitude of their influence on the rest of the system. Based on the premise that the most influential components might serve as better drug targets, we characterized them for biological functions, housekeeping genes, essential genes, and druggable proteins. The most influential components under all environmental conditions were enriched with several biological processes. The inositol pathway was found as most influential under inactivating perturbations, whereas the kinase and small lung cancer pathways were identified as the most influential under activating perturbations. The most influential components were enriched with essential genes and druggable proteins. Moreover, known cancer drug targets were also classified in influential components based on the affected components in the network. Additionally, the systemic perturbation analysis of the model revealed a network motif of most influential components which affect each other. Furthermore, our analysis predicted novel combinations of cancer drug targets with various effects on other most influential components. We found that the combinatorial perturbation consisting of PI3K inactivation and overactivation of IP3R1 can lead to increased activity levels of apoptosis

  5. Role of medullary GABA signal transduction on parasympathetic reflex vasodilatation in the lower lip.

    PubMed

    Kawakami, So; Izumi, Hiroshi; Masaki, Eiji; Kuchiiwa, Satoshi; Mizuta, Kentaro

    2012-02-01

    significantly reduced this reflex vasodilatation. These results suggest that medullary GABA signal transduction inhibits the parasympathetic reflex vasodilatation in the rat lower lip via GABA(A) and GABA(B) receptors in the Vsp and the ISN.

  6. Signal transduction and transcriptional and posttranscriptional control of iron-regulated genes in bacteria.

    PubMed Central

    Crosa, J H

    199