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Sample records for active signaling state

  1. Conformational transition in signal transduction: metastable states and transition pathways in the activation of a signaling protein.

    PubMed

    Banerjee, Rahul; Yan, Honggao; Cukier, Robert I

    2015-06-01

    Signal transduction is of vital importance to the growth and adaptation of living organisms. The key to understand mechanisms of biological signal transduction is elucidation of the conformational dynamics of its signaling proteins, as the activation of a signaling protein is fundamentally a process of conformational transition from an inactive to an active state. A predominant form of signal transduction for bacterial sensing of environmental changes in the wild or inside their hosts is a variety of two-component systems, in which the conformational transition of a response regulator (RR) from an inactive to an active state initiates responses to the environmental changes. Here, RR activation has been investigated using RR468 as a model system by extensive unbiased all-atom molecular dynamics (MD) simulations in explicit solvent, starting from snapshots along a targeted MD trajectory that covers the conformational transition. Markov state modeling, transition path theory, and geometric analyses of the wealth of the MD data have provided a comprehensive description of the RR activation. It involves a network of metastable states, with one metastable state essentially the same as the inactive state and another very similar to the active state that are connected via a small set of intermediates. Five major pathways account for >75% of the fluxes of the conformational transition from the inactive to the active-like state. The thermodynamic stability of the states and the activation barriers between states are found, to identify rate-limiting steps. The conformal transition is initiated predominantly by movements of the β3α3 loop, followed by movements of the β4α4-loop and neighboring α4 helix region, and capped by additional movements of the β3α3 loop. A number of transient hydrophobic and hydrogen bond interactions are revealed, and they may be important for the conformational transition. PMID:25945797

  2. Neuropeptidergic Signaling and Active Feeding State Inhibit Nociception in Caenorhabditis elegans.

    PubMed

    Ezcurra, Marina; Walker, Denise S; Beets, Isabel; Swoboda, Peter; Schafer, William R

    2016-03-16

    Food availability and nutritional status are important cues affecting behavioral states. Here we report that, in Caenorhabditis elegans, a cascade of dopamine and neuropeptide signaling acts to inhibit nociception in food-poor environments. In the absence of food, animals show decreased sensitivity and increased adaptation to soluble repellents sensed by the polymodal ASH nociceptors. The effects of food on adaptation are affected by dopamine and neuropeptide signaling; dopamine acts via the DOP-1 receptor to decrease adaptation on food, whereas the neuropeptide receptors NPR-1 and NPR-2 act to increase adaptation off food. NPR-1 and NPR-2 function cell autonomously in the ASH neurons to increase adaptation off food, whereas the DOP-1 receptor controls neuropeptide release from interneurons that modulate ASH activity indirectly. These results indicate that feeding state modulates nociception through the interaction of monoamine and neuropeptide signaling pathways. PMID:26985027

  3. Neuropeptidergic Signaling and Active Feeding State Inhibit Nociception in Caenorhabditis elegans

    PubMed Central

    Ezcurra, Marina; Walker, Denise S.; Beets, Isabel; Swoboda, Peter

    2016-01-01

    Food availability and nutritional status are important cues affecting behavioral states. Here we report that, in Caenorhabditis elegans, a cascade of dopamine and neuropeptide signaling acts to inhibit nociception in food-poor environments. In the absence of food, animals show decreased sensitivity and increased adaptation to soluble repellents sensed by the polymodal ASH nociceptors. The effects of food on adaptation are affected by dopamine and neuropeptide signaling; dopamine acts via the DOP-1 receptor to decrease adaptation on food, whereas the neuropeptide receptors NPR-1 and NPR-2 act to increase adaptation off food. NPR-1 and NPR-2 function cell autonomously in the ASH neurons to increase adaptation off food, whereas the DOP-1 receptor controls neuropeptide release from interneurons that modulate ASH activity indirectly. These results indicate that feeding state modulates nociception through the interaction of monoamine and neuropeptide signaling pathways. PMID:26985027

  4. Signaling Pathways That Control Rho Kinase Activity Maintain the Embryonic Epicardial Progenitor State

    PubMed Central

    Artamonov, Mykhaylo V.; Jin, Li; Franke, Aaron S.; Momotani, Ko; Ho, Ruoya; Dong, Xiu Rong; Majesky, Mark W.; Somlyo, Avril V.

    2015-01-01

    This study identifies signaling pathways that play key roles in the formation and maintenance of epicardial cells, a source of progenitors for coronary smooth muscle cells (SMCs). After epithelial to mesenchymal transition (EMT), mesenchymal cells invade the myocardium to form coronary SMCs. RhoA/Rho kinase activity is required for EMT and for differentiation into coronary SMCs, whereas cAMP activity is known to inhibit EMT in epithelial cells by an unknown mechanism. We use outgrowth of epicardial cells from E9.5 isolated mouse proepicardium (PE) explants, wild type and Epac1 null E12.5 mouse heart explants, adult rat epicardial cells, and immortalized mouse embryonic epicardial cells as model systems to identify signaling pathways that regulate RhoA activity to maintain the epicardial progenitor state. We demonstrate that RhoA activity is suppressed in the epicardial progenitor state, that the cAMP-dependent Rap1 GTP exchange factor (GEF), Epac, known to down-regulate RhoA activity through activation of Rap1 GTPase activity increased, that Rap1 activity increased, and that expression of the RhoA antagonistic Rnd proteins known to activate p190RhoGAP increased and associated with p190RhoGAP. Finally, EMT is associated with increased p63RhoGEF and RhoGEF-H1 protein expression, increased GEF-H1 activity, with a trend in increased p63RhoGEF activity. EMT is suppressed by partial silencing of p63RhoGEF and GEF-H1. In conclusion, we have identified new signaling molecules that act together to control RhoA activity and play critical roles in the maintenance of coronary smooth muscle progenitor cells in the embryonic epicardium. We suggest that their eventual manipulation could promote revascularization after myocardial injury. PMID:25733666

  5. The two active X chromosomes in female ESCs block exit from the pluripotent state by modulating the ESC signaling network.

    PubMed

    Schulz, Edda G; Meisig, Johannes; Nakamura, Tomonori; Okamoto, Ikuhiro; Sieber, Anja; Picard, Christel; Borensztein, Maud; Saitou, Mitinori; Blüthgen, Nils; Heard, Edith

    2014-02-01

    During early development of female mouse embryos, both X chromosomes are transiently active. X gene dosage is then equalized between the sexes through the process of X chromosome inactivation (XCI). Whether the double dose of X-linked genes in females compared with males leads to sex-specific developmental differences has remained unclear. Using embryonic stem cells with distinct sex chromosome compositions as a model system, we show that two X chromosomes stabilize the naive pluripotent state by inhibiting MAPK and Gsk3 signaling and stimulating the Akt pathway. Since MAPK signaling is required to exit the pluripotent state, differentiation is paused in female cells as long as both X chromosomes are active. By preventing XCI or triggering it precociously, we demonstrate that this differentiation block is released once XX cells have undergone X inactivation. We propose that double X dosage interferes with differentiation, thus ensuring a tight coupling between X chromosome dosage compensation and development. PMID:24506884

  6. Chemogenetic and Optogenetic Activation of Gαs Signaling in the Basolateral Amygdala Induces Acute and Social Anxiety-Like States.

    PubMed

    Siuda, Edward R; Al-Hasani, Ream; McCall, Jordan G; Bhatti, Dionnet L; Bruchas, Michael R

    2016-07-01

    Anxiety disorders are debilitating psychiatric illnesses with detrimental effects on human health. These heightened states of arousal are often in the absence of obvious threatening cues and are difficult to treat owing to a lack of understanding of the neural circuitry and cellular machinery mediating these conditions. Activation of noradrenergic circuitry in the basolateral amygdala is thought to have a role in stress, fear, and anxiety, and the specific cell and receptor types responsible is an active area of investigation. Here we take advantage of two novel cellular approaches to dissect the contributions of G-protein signaling in acute and social anxiety-like states. We used a chemogenetic approach utilizing the Gαs DREADD (rM3Ds) receptor and show that selective activation of generic Gαs signaling is sufficient to induce acute and social anxiety-like behavioral states in mice. Second, we use a recently characterized chimeric receptor composed of rhodopsin and the β2-adrenergic receptor (Opto-β2AR) with in vivo optogenetic techniques to selectively activate Gαs β-adrenergic signaling exclusively within excitatory neurons of the basolateral amygdala. We found that optogenetic induction of β-adrenergic signaling in the basolateral amygdala is sufficient to induce acute and social anxiety-like behavior. These findings support the conclusion that activation of Gαs signaling in the basolateral amygdala has a role in anxiety. These data also suggest that acute and social anxiety-like states may be mediated through signaling pathways identical to β-adrenergic receptors, thus providing support that inhibition of this system may be an effective anxiolytic therapy. PMID:26725834

  7. Signal focusing through active transport

    NASA Astrophysics Data System (ADS)

    Godec, Aljaž; Metzler, Ralf

    2015-07-01

    The accuracy of molecular signaling in biological cells and novel diagnostic devices is ultimately limited by the counting noise floor imposed by the thermal diffusion. Motivated by the fact that messenger RNA and vesicle-engulfed signaling molecules transiently bind to molecular motors and are actively transported in biological cells, we show here that the random active delivery of signaling particles to within a typical diffusion distance to the receptor generically reduces the correlation time of the counting noise. Considering a variety of signaling particle sizes from mRNA to vesicles and cell sizes from prokaryotic to eukaryotic cells, we show that the conditions for active focusing—faster and more precise signaling—are indeed compatible with observations in living cells. Our results improve the understanding of molecular cellular signaling and novel diagnostic devices.

  8. The Fatty Acid Signaling Molecule cis-2-Decenoic Acid Increases Metabolic Activity and Reverts Persister Cells to an Antimicrobial-Susceptible State

    PubMed Central

    Morozov, Aleksey; Planzos, Penny; Zelaya, Hector M.

    2014-01-01

    Persister cells, which are tolerant to antimicrobials, contribute to biofilm recalcitrance to therapeutic agents. In turn, the ability to kill persister cells is believed to significantly improve efforts in eradicating biofilm-related, chronic infections. While much research has focused on elucidating the mechanism(s) by which persister cells form, little is known about the mechanism or factors that enable persister cells to revert to an active and susceptible state. Here, we demonstrate that cis-2-decenoic acid (cis-DA), a fatty acid signaling molecule, is able to change the status of Pseudomonas aeruginosa and Escherichia coli persister cells from a dormant to a metabolically active state without an increase in cell number. This cell awakening is supported by an increase of the persister cells' respiratory activity together with changes in protein abundance and increases of the transcript expression levels of several metabolic markers, including acpP, 16S rRNA, atpH, and ppx. Given that most antimicrobials target actively growing cells, we also explored the effect of cis-DA on enhancing antibiotic efficacy in killing persister cells due to their inability to keep a persister cell state. Compared to antimicrobial treatment alone, combinational treatments of persister cell subpopulations with antimicrobials and cis-DA resulted in a significantly greater decrease in cell viability. In addition, the presence of cis-DA led to a decrease in the number of persister cells isolated. We thus demonstrate the ability of a fatty acid signaling molecule to revert bacterial cells from a tolerant phenotype to a metabolically active, antimicrobial-sensitive state. PMID:25192989

  9. A P-loop mutation in Gα subunits prevents transition to the active state: implications for G-protein signaling in fungal pathogenesis.

    PubMed

    Bosch, Dustin E; Willard, Francis S; Ramanujam, Ravikrishna; Kimple, Adam J; Willard, Melinda D; Naqvi, Naweed I; Siderovski, David P

    2012-02-01

    Heterotrimeric G-proteins are molecular switches integral to a panoply of different physiological responses that many organisms make to environmental cues. The switch from inactive to active Gαβγ heterotrimer relies on nucleotide cycling by the Gα subunit: exchange of GTP for GDP activates Gα, whereas its intrinsic enzymatic activity catalyzes GTP hydrolysis to GDP and inorganic phosphate, thereby reverting Gα to its inactive state. In several genetic studies of filamentous fungi, such as the rice blast fungus Magnaporthe oryzae, a G42R mutation in the phosphate-binding loop of Gα subunits is assumed to be GTPase-deficient and thus constitutively active. Here, we demonstrate that Gα(G42R) mutants are not GTPase deficient, but rather incapable of achieving the activated conformation. Two crystal structure models suggest that Arg-42 prevents a typical switch region conformational change upon Gα(i1)(G42R) binding to GDP·AlF(4)(-) or GTP, but rotameric flexibility at this locus allows for unperturbed GTP hydrolysis. Gα(G42R) mutants do not engage the active state-selective peptide KB-1753 nor RGS domains with high affinity, but instead favor interaction with Gβγ and GoLoco motifs in any nucleotide state. The corresponding Gα(q)(G48R) mutant is not constitutively active in cells and responds poorly to aluminum tetrafluoride activation. Comparative analyses of M. oryzae strains harboring either G42R or GTPase-deficient Q/L mutations in the Gα subunits MagA or MagB illustrate functional differences in environmental cue processing and intracellular signaling outcomes between these two Gα mutants, thus demonstrating the in vivo functional divergence of G42R and activating G-protein mutants. PMID:22383884

  10. A P-loop Mutation in Gα Subunits Prevents Transition to the Active State: Implications for G-protein Signaling in Fungal Pathogenesis

    PubMed Central

    Ramanujam, Ravikrishna; Kimple, Adam J.; Willard, Melinda D.; Naqvi, Naweed I.; Siderovski, David P.

    2012-01-01

    Heterotrimeric G-proteins are molecular switches integral to a panoply of different physiological responses that many organisms make to environmental cues. The switch from inactive to active Gαβγ heterotrimer relies on nucleotide cycling by the Gα subunit: exchange of GTP for GDP activates Gα, whereas its intrinsic enzymatic activity catalyzes GTP hydrolysis to GDP and inorganic phosphate, thereby reverting Gα to its inactive state. In several genetic studies of filamentous fungi, such as the rice blast fungus Magnaporthe oryzae, a G42R mutation in the phosphate-binding loop of Gα subunits is assumed to be GTPase-deficient and thus constitutively active. Here, we demonstrate that Gα(G42R) mutants are not GTPase deficient, but rather incapable of achieving the activated conformation. Two crystal structure models suggest that Arg-42 prevents a typical switch region conformational change upon Gαi1(G42R) binding to GDP·AlF4− or GTP, but rotameric flexibility at this locus allows for unperturbed GTP hydrolysis. Gα(G42R) mutants do not engage the active state-selective peptide KB-1753 nor RGS domains with high affinity, but instead favor interaction with Gβγ and GoLoco motifs in any nucleotide state. The corresponding Gαq(G48R) mutant is not constitutively active in cells and responds poorly to aluminum tetrafluoride activation. Comparative analyses of M. oryzae strains harboring either G42R or GTPase-deficient Q/L mutations in the Gα subunits MagA or MagB illustrate functional differences in environmental cue processing and intracellular signaling outcomes between these two Gα mutants, thus demonstrating the in vivo functional divergence of G42R and activating G-protein mutants. PMID:22383884

  11. A P-loop Mutation in G[alpha] Subunits Prevents Transition to the Active State: Implications for G-protein Signaling in Fungal Pathogenesis

    SciTech Connect

    Bosch, Dustin E.; Willard, Francis S.; Ramanujam, Ravikrishna; Kimple, Adam J.; Willard, Melinda D.; Naqvi, Naweed I.; Siderovski, David P.

    2012-10-23

    Heterotrimeric G-proteins are molecular switches integral to a panoply of different physiological responses that many organisms make to environmental cues. The switch from inactive to active G{alpha}{beta}{gamma} heterotrimer relies on nucleotide cycling by the G{alpha} subunit: exchange of GTP for GDP activates G{alpha}, whereas its intrinsic enzymatic activity catalyzes GTP hydrolysis to GDP and inorganic phosphate, thereby reverting G{alpha} to its inactive state. In several genetic studies of filamentous fungi, such as the rice blast fungus Magnaporthe oryzae, a G42R mutation in the phosphate-binding loop of G{alpha} subunits is assumed to be GTPase-deficient and thus constitutively active. Here, we demonstrate that G{alpha}(G42R) mutants are not GTPase deficient, but rather incapable of achieving the activated conformation. Two crystal structure models suggest that Arg-42 prevents a typical switch region conformational change upon G{alpha}{sub i1}(G42R) binding to GDP {center_dot} AlF{sub 4}{sup -} or GTP, but rotameric flexibility at this locus allows for unperturbed GTP hydrolysis. G{alpha}(G42R) mutants do not engage the active state-selective peptide KB-1753 nor RGS domains with high affinity, but instead favor interaction with G{beta}{gamma} and GoLoco motifs in any nucleotide state. The corresponding G{alpha}{sub q}(G48R) mutant is not constitutively active in cells and responds poorly to aluminum tetrafluoride activation. Comparative analyses of M. oryzae strains harboring either G42R or GTPase-deficient Q/L mutations in the G{alpha} subunits MagA or MagB illustrate functional differences in environmental cue processing and intracellular signaling outcomes between these two G{alpha} mutants, thus demonstrating the in vivo functional divergence of G42R and activating G-protein mutants.

  12. [Xinfeng capsule improves hypercoagulative state by inhibiting miR-155/NF-κB signaling pathway in patients with active ankylosing spondylitis].

    PubMed

    Fang, Li; Liu, Jian; Wan, Lei; Zhu, Fubing; Tan, Bing; Zhang, Pingheng

    2016-08-01

    Objective To observe the effect of Xinfeng capsule (XFC) on miR-155, nuclear factor kappa B (NF-κB) signal pathway, and indexes related to hypercoagulative state in patients with active ankylosing spondylitis (AS), and investigate the possible mechanism. Methods Fifty-six cases in active AS were randomly divided into XFC group and sulfasalazine (SASP) group. All cases in the XFC group took three capsules three times daily for twelve consecutive weeks. The ones in the SASP group took four tablets two times daily for twelve consecutive weeks. The expression of miR-155 was detected by real-time PCR. The mRNA expressions of nuclear factor κB activator 1(Act1), NF-κB inhibitor-alpha (IκBα), inhibitor of kappa-B kinase beta (IKKβ), NF-κB p65, and NF-κB p50 were tested by reverse transcription PCR (RT-PCR). Meanwhile, the protein expressions of NF-κB P65 and NF-κB P50 were determined by Western blotting. Tumor necrosis factor-alpha (TNF-α), interleukin (IL)-4, IL-10, IL-17, thromboxane B2 (TXB2), 6-ketone-prostaglandin F1 (6-keto-PGF1), platelet granular membrane protein 140 (GMP140), platelet activation factor (PAF), and plasminogen activator inhibitor-2 (PAI-2) were determined by ELISA. Clinical efficacy was evaluated in the two groups. Results Compared with the SASP group, 50% Bath ankylosing spondylitis disease activity index (BASDAI50) was significantly higher in the XFC group. Compared with the SASP group after treatment, platelet (PLT), fibrinogen (FBG) and D-D dimer (D-D), TXB2, GMP140, PAF, PAI-2, IL-17, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), visual analog scale (VAS), BASDAI, BASFI, and BAS-G were reduced more obviously in the XFC group after treatment; meanwhile, 6-keto-PGF1, IL-4, and IL-10 significantly increased. Compared with the SASP group after treatment, the expressions of IKKβ mRNA, IκBα mRNA, NF-κB p65 mRNA, NF-κB p50 mRNA, NF-κB P65 protein, NF-κB P50 protein, and miR-155 were lower in the XFC group after

  13. The Use of Audible Traffic Signals in the United States.

    ERIC Educational Resources Information Center

    Peck, A. F.; Uslan, M.

    1990-01-01

    This paper discusses audible traffic signals (ATS) and their use by visually impaired pedestrians in the United States and other countries. Areas of concern are noted, including the types of intersections at which ATS should be installed, the locations of poles and buttons for activating the system, and the specific type of device used.…

  14. Tautomeric states of the active-site histidines of phosphorylated and unphosphorylated IIIGlc, a signal-transducing protein from Escherichia coli, using two-dimensional heteronuclear NMR techniques.

    PubMed Central

    Pelton, J. G.; Torchia, D. A.; Meadow, N. D.; Roseman, S.

    1993-01-01

    IIIGlc is an 18.1-kDa signal-transducing phosphocarrier protein of the phosphoenolpyruvate:glycose phosphotransferase system from Escherichia coli. The 1H, 15N, and 13C histidine ring NMR signals of both the phosphorylated and unphosphorylated forms of IIIGlc have been assigned using two-dimensional 1H-15N and 1H-13C heteronuclear multiple-quantum coherence (HMQC) experiments and a two-dimensional 13C-13C-1H correlation spectroscopy via JCC coupling experiment. The data were acquired on uniformly 15N-labeled and uniformly 15N/13C-labeled protein samples. The experiments rely on one-bond and two-bond J couplings that allowed for assignment of the signals without the need for the analysis of through-space (nuclear Overhauser effect spectroscopy) correlations. The 15N and 13C chemical shifts were used to determine that His-75 exists predominantly in the N epsilon 2-H tautomeric state in both the phosphorylated and unphosphorylated forms of IIIGlc, and that His-90 exists primarily in the N delta 1-H state in the unphosphorylated protein. Upon phosphorylation of the N epsilon 2 nitrogen of His-90, the N delta 1 nitrogen remains protonated, resulting in the formation of a charged phospho-His-90 moiety. The 1H, 15N, and 13C signals of the phosphorylated and unphosphorylated proteins showed only minor shifts in the pH range from 6.0 to 9.0. These data indicate that the pK alpha values for both His-75 and His-90 in IIIGlc and His-75 in phospho-IIIGlc are less than 5.0, and that the pK alpha value for phospho-His-90 is greater than 10. The results are presented in relation to previously obtained structural data on IIIGlc, and implications for proposed mechanisms of phosphoryl transfer are discussed. PMID:8518729

  15. Signaling during platelet adhesion and activation

    PubMed Central

    Li, Zhenyu; Delaney, M. Keegan; O’Brien, Kelly A.; Du, Xiaoping

    2011-01-01

    Upon vascular injury, platelets are activated by adhesion to adhesive proteins like von Willebrand factor and collagen, or by soluble platelet agonists like ADP, thrombin, and thromboxane A2. These adhesive proteins and soluble agonists induce signal transduction via their respective receptors. The various receptor-specific platelet activation signaling pathways converge into common signaling events, which stimulate platelet shape change, granule secretion, and ultimately induce the “inside-out” signaling process leading to activation of the ligand binding function of integrin αIIbβ3. Ligand binding to integrin αIIbβ3 mediates platelet adhesion and aggregation and triggers “outside-in” signaling, resulting in platelet spreading, additional granule secretion, stabilization of platelet adhesion and aggregation, and clot retraction. It has become increasingly evident that agonist-induced platelet activation signals also crosstalk with integrin “outside-in” signals to regulate platelet responses. Platelet activation involves a series of rapid positive feedback loops that greatly amplify initial activation signals, and enable robust platelet recruitment and thrombus stabilization. Recent studies have provided novel insight into the molecular mechanisms of these processes. PMID:21071698

  16. Heat dissipation guides activation in signaling proteins

    PubMed Central

    Weber, Jeffrey K.; Shukla, Diwakar; Pande, Vijay S.

    2015-01-01

    Life is fundamentally a nonequilibrium phenomenon. At the expense of dissipated energy, living things perform irreversible processes that allow them to propagate and reproduce. Within cells, evolution has designed nanoscale machines to do meaningful work with energy harnessed from a continuous flux of heat and particles. As dictated by the Second Law of Thermodynamics and its fluctuation theorem corollaries, irreversibility in nonequilibrium processes can be quantified in terms of how much entropy such dynamics produce. In this work, we seek to address a fundamental question linking biology and nonequilibrium physics: can the evolved dissipative pathways that facilitate biomolecular function be identified by their extent of entropy production in general relaxation processes? We here synthesize massive molecular dynamics simulations, Markov state models (MSMs), and nonequilibrium statistical mechanical theory to probe dissipation in two key classes of signaling proteins: kinases and G-protein–coupled receptors (GPCRs). Applying machinery from large deviation theory, we use MSMs constructed from protein simulations to generate dynamics conforming to positive levels of entropy production. We note the emergence of an array of peaks in the dynamical response (transient analogs of phase transitions) that draw the proteins between distinct levels of dissipation, and we see that the binding of ATP and agonist molecules modifies the observed dissipative landscapes. Overall, we find that dissipation is tightly coupled to activation in these signaling systems: dominant entropy-producing trajectories become localized near important barriers along known biological activation pathways. We go on to classify an array of equilibrium and nonequilibrium molecular switches that harmonize to promote functional dynamics. PMID:26240354

  17. Heat dissipation guides activation in signaling proteins.

    PubMed

    Weber, Jeffrey K; Shukla, Diwakar; Pande, Vijay S

    2015-08-18

    Life is fundamentally a nonequilibrium phenomenon. At the expense of dissipated energy, living things perform irreversible processes that allow them to propagate and reproduce. Within cells, evolution has designed nanoscale machines to do meaningful work with energy harnessed from a continuous flux of heat and particles. As dictated by the Second Law of Thermodynamics and its fluctuation theorem corollaries, irreversibility in nonequilibrium processes can be quantified in terms of how much entropy such dynamics produce. In this work, we seek to address a fundamental question linking biology and nonequilibrium physics: can the evolved dissipative pathways that facilitate biomolecular function be identified by their extent of entropy production in general relaxation processes? We here synthesize massive molecular dynamics simulations, Markov state models (MSMs), and nonequilibrium statistical mechanical theory to probe dissipation in two key classes of signaling proteins: kinases and G-protein-coupled receptors (GPCRs). Applying machinery from large deviation theory, we use MSMs constructed from protein simulations to generate dynamics conforming to positive levels of entropy production. We note the emergence of an array of peaks in the dynamical response (transient analogs of phase transitions) that draw the proteins between distinct levels of dissipation, and we see that the binding of ATP and agonist molecules modifies the observed dissipative landscapes. Overall, we find that dissipation is tightly coupled to activation in these signaling systems: dominant entropy-producing trajectories become localized near important barriers along known biological activation pathways. We go on to classify an array of equilibrium and nonequilibrium molecular switches that harmonize to promote functional dynamics. PMID:26240354

  18. Signal peptides are allosteric activators of the protein translocase.

    PubMed

    Gouridis, Giorgos; Karamanou, Spyridoula; Gelis, Ioannis; Kalodimos, Charalampos G; Economou, Anastassios

    2009-11-19

    Extra-cytoplasmic polypeptides are usually synthesized as 'preproteins' carrying amino-terminal, cleavable signal peptides and secreted across membranes by translocases. The main bacterial translocase comprises the SecYEG protein-conducting channel and the peripheral ATPase motor SecA. Most proteins destined for the periplasm and beyond are exported post-translationally by SecA. Preprotein targeting to SecA is thought to involve signal peptides and chaperones like SecB. Here we show that signal peptides have a new role beyond targeting: they are essential allosteric activators of the translocase. On docking on their binding groove on SecA, signal peptides act in trans to drive three successive states: first, 'triggering' that drives the translocase to a lower activation energy state; second, 'trapping' that engages non-native preprotein mature domains docked with high affinity on the secretion apparatus; and third, 'secretion' during which trapped mature domains undergo several turnovers of translocation in segments. A significant contribution by mature domains renders signal peptides less critical in bacterial secretory protein targeting than currently assumed. Rather, it is their function as allosteric activators of the translocase that renders signal peptides essential for protein secretion. A role for signal peptides and targeting sequences as allosteric activators may be universal in protein translocases. PMID:19924216

  19. Adenosine Signaling During Acute and Chronic Disease States

    PubMed Central

    Karmouty-Quintana, Harry; Xia, Yang; Blackburn, Michael R.

    2013-01-01

    Adenosine is a signaling nucleoside that is produced following tissue injury, particularly injury involving ischemia and hypoxia. The production of extracellular adenosine and its subsequent signaling through adenosine receptors plays an important role in orchestrating injury responses in multiple organs. There are four adenosine receptors that are widely distributed on immune, epithelial, endothelial, neuronal and stromal cells throughout the body. Interestingly, these receptors are subject to altered regulation following injury. Studies in mouse models and human cells and tissues have identified that the production of adenosine and its subsequent signaling through its receptors plays largely beneficial roles in acute disease states, with the exception of brain injury. In contrast, if elevated adenosine levels are sustained beyond the acute injury phase, adenosine responses can become detrimental by activating pathways that promote tissue injury and fibrosis. Understanding when during the course of disease adenosine signaling is beneficial as opposed to detrimental and defining the mechanisms involved will be critical for the advancement of adenosine based therapies for acute and chronic diseases. The purpose of this review is to discuss key observations that define the beneficial and detrimental aspects of adenosine signaling during acute and chronic disease states with an emphasis on cellular processes such as inflammatory cell regulation, vascular barrier function and tissue fibrosis. PMID:23340998

  20. Preparation protocols for high-activity photosystem II membrane particles of green algae and higher plants, pH dependence of oxygen evolution and comparison of the S2-state multiline signal by X-band EPR spectroscopy.

    PubMed

    Schiller, H; Dau, H

    2000-01-01

    Photosystem II (PS II) membrane particles are particularly well suited for various types of spectroscopic investigations on the PS II manganese complex. Here we present: (1) a preparation protocol for PS II membrane particles of higher plants, which yields exceptionally high oxygen-evolution activity due to the use of glycinebetaine as a PS II-stabilizing agent; (2) preparation protocols for highly active PS II membrane particles for the green algae Scenedesmus obliquus and Chlamydomonas reinhardtii; (3) a determination of pH dependence of oxygen evolution for spinach and Scenedesmus; (4) a comparison of the EPR multiline signal observed in the S2-state of green algae and higher plants of PS II membrane particles. A clearly broader type of multiline EPR signal is observed in green algae. PMID:10942078

  1. Paired inhibitory and activating receptor signals.

    PubMed

    Taylor, L S; Paul, S P; McVicar, D W

    2000-01-01

    The immunological literature has become inundated with reports regarding paired inhibitory receptors. Paired inhibitory receptor systems are highly conserved families that contain receptors involved in either cellular inhibition or activation. In most cases the paired putative biochemical antagonists are co-expressed on a given cell and thought to bind similar, if not identical, ligands making their biological role difficult to understand. Examples of these systems include immunoglobulin (Ig)-like receptors (Killer Ig Receptors, Immunoglobulin-like Transcripts/Leukocyte Ig-like Receptors/Monocyte Macrophage Ig Receptors, and Paired Ig-like Receptors), and type II lectin-like receptor systems (NKG2 and Ly49). General characteristics of these inhibitory receptors include a cytoplasmic immunoreceptor tyrosine-based inhibitory motif (ITIM). The ITIM is phosphorylated upon engagement and recruits protein tyrosine phosphatases that dephosphorylate cellular substrates that would otherwise mediate activation. In contrast, the activating receptors of these pairs use charged residues within their transmembrane domains to associate with various signal transduction chains including the gamma chain of the receptor for the Fc portion of IgE, DAP12 or DAP10. Once phosphorylated, these chains direct the signal transduction cascade resulting in cellular activation. Here we review the signaling of several paired systems and present the current models for their signal transduction cascades. PMID:11258418

  2. Subject identification through standard EEG signals during resting states.

    PubMed

    De Vico Fallani, F; Vecchiato, G; Toppi, J; Astolfi, L; Babiloni, F

    2011-01-01

    In the present work, we used the brain electroencephalografic activity as an alternative means to identify individuals. 50 healthy subjects participated to the study and 56 EEG signals were recorded through a high-density cap during one minute of resting state either with eyes open and eyes closed. By computing the power spectrum density (PSD) on segments of 10 seconds, we obtained a feature vector of 40 points, notably the PSD values in the standard frequency range (1-40 Hz), for each EEG channel. By using a naive Bayes classifier and K-fold cross-validations, we observed high correct recognition rates (CRR) at the parieto-occipital electrodes (~78% during eyes open, ~89% during eyes closed). Notably, the eyes closed resting state elicited the highest CRRs at the occipital electrodes (92% O2, 91% O1), suggesting these biometric characteristics as the most suitable, among those investigated here, for identifying individuals. PMID:22254808

  3. Compressibility of Quantum Mixed-State Signals

    SciTech Connect

    Koashi, Masato; Imoto, Nobuyuki

    2001-07-02

    We present a formula that determines the optimal number of qubits per message that allows asymptotically faithful compression of the quantum information carried by an ensemble of mixed states. The set of mixed states determines a decomposition of the Hilbert space into the redundant part and the irreducible part. After removing the redundancy, the optimal compression rate is shown to be given by the von Neumann entropy of the reduced ensemble.

  4. Notum deacylates Wnts to suppress signalling activity

    PubMed Central

    Howell, Steve; Chang, Tao-Hsin; Liu, Yan; Feizi, Ten; Bineva, Ganka; O’Reilly, Nicola; Snijders, Ambrosius P.; Jones, E. Yvonne; Vincent, Jean-Paul

    2015-01-01

    Signalling by Wnts is finely balanced to ensure normal development and tissue homeostasis while avoiding diseases such as cancer. This is achieved in part by Notum, a highly conserved secreted feedback antagonist. Notum has been thought to act as a phospholipase, shedding glypicans and associated Wnts from the cell surface. However, this view fails to explain specificity since glypicans bind many extracellular ligands. Here we provide genetic evidence in Drosophila that Notum requires glypicans to suppress Wnt signalling, but does not cleave their glycophosphatidylinositol anchor. Structural analyses reveal glycosaminoglycan binding sites on Notum, which likely help Notum colocalise with Wnts. They also identify, at the active site of human and Drosophila Notum, a large hydrophobic pocket that accommodates palmitoleate. Kinetic and mass spectrometric analyses of human proteins show that Notum is a carboxylesterase that removes an essential palmitoleate moiety from Wnts and thus constitutes the first known extracellular protein deacylase. PMID:25731175

  5. Modeling of cortical signals using echo state networks

    NASA Astrophysics Data System (ADS)

    Zhou, Hanying; Wang, Yongji; Huang, Jiangshuai

    2009-10-01

    Diverse modeling frameworks have been utilized with the ultimate goal of translating brain cortical signals into prediction of visible behavior. The inputs to these models are usually multidimensional neural recordings collected from relevant regions of a monkey's brain while the outputs are the associated behavior which is typically the 2-D or 3-D hand position of a primate. Here our task is to set up a proper model in order to figure out the move trajectories by input the neural signals which are simultaneously collected in the experiment. In this paper, we propose to use Echo State Networks (ESN) to map the neural firing activities into hand positions. ESN is a newly developed recurrent neural network(RNN) model. Besides its dynamic property and short term memory just as other recurrent neural networks have, it has a special echo state property which endows it with the ability to model nonlinear dynamic systems powerfully. What distinguished it from transitional recurrent neural networks most significantly is its special learning method. In this paper we train this net with a refined version of its typical training method and get a better model.

  6. Thiol/disulfide redox states in signaling and sensing

    PubMed Central

    Go, Young-Mi; Jones, Dean P.

    2015-01-01

    Rapid advances in redox systems biology are creating new opportunities to understand complexities of human disease and contributions of environmental exposures. New understanding of thiol-disulfide systems have occurred during the past decade as a consequence of the discoveries that thiol and disulfide systems are maintained in kinetically controlled steady-states displaced from thermodynamic equilibrium, that a widely distributed family of NADPH oxidases produces oxidants that function in cell signaling, and that a family of peroxiredoxins utilize thioredoxin as a reductant to complement the well-studied glutathione antioxidant system for peroxide elimination and redox regulation. This review focuses on thiol/disulfide redox state in biologic systems and the knowledge base available to support development of integrated redox systems biology models to better understand the function and dysfunction of thiol-disulfide redox systems. In particular, central principles have emerged concerning redox compartmentalization and utility of thiol/disulfide redox measures as indicators of physiologic function. Advances in redox proteomics show that, in addition to functioning in protein active sites and cell signaling, cysteine residues also serve as redox sensors to integrate biologic functions. These advances provide a framework for translation of redox systems biology concepts to practical use in understanding and treating human disease. Biological responses to cadmium, a widespread environmental agent, are used to illustrate the utility of these advances to the understanding of complex pleiotropic toxicities. PMID:23356510

  7. A verification logic representation of indeterministic signal states

    NASA Technical Reports Server (NTRS)

    Gambles, J. W.; Windley, P. J.

    1991-01-01

    The integration of modern CAD tools with formal verification environments require translation from hardware description language to verification logic. A signal representation including both unknown state and a degree of strength indeterminacy is essential for the correct modeling of many VLSI circuit designs. A higher-order logic theory of indeterministic logic signals is presented.

  8. Activators of G Protein Signaling in the Kidney

    PubMed Central

    2015-01-01

    Heterotrimeric G proteins play a crucial role in regulating signal processing to maintain normal cellular homeostasis, and subtle perturbations in its activity can potentially lead to the pathogenesis of renal disorders or diseases. Cell-surface receptors and accessory proteins, which normally modify and organize the coupling of individual G protein subunits, contribute to the regulation of heterotrimeric G protein activity and their convergence and/or divergence of downstream signaling initiated by effector systems. Activators of G protein signaling (AGS) are a family of accessory proteins that intervene at multiple distinct points during the activation–inactivation cycle of G proteins, even in the absence of receptor stimulation. Perturbations in the expression of individual AGS proteins have been reported to modulate signal transduction pathways in a wide array of diseases and disorders within the brain, heart, immune system, and more recently, the kidney. This review will provide an overview of the expression profile, localization, and putative biologic role of the AGS family in the context of normal and diseased states of the kidney. PMID:25628392

  9. The Signaling State of Orange Carotenoid Protein

    PubMed Central

    Maksimov, Eugene G.; Shirshin, Evgeny A.; Sluchanko, Nikolai N.; Zlenko, Dmitry V.; Parshina, Evgenia Y.; Tsoraev, Georgy V.; Klementiev, Konstantin E.; Budylin, Gleb S.; Schmitt, Franz-Josef; Friedrich, Thomas; Fadeev, Victor V.; Paschenko, Vladimir Z.; Rubin, Andrew B.

    2015-01-01

    Orange carotenoid protein (OCP) is the photoactive protein that is responsible for high light tolerance in cyanobacteria. We studied the kinetics of the OCP photocycle by monitoring changes in its absorption spectrum, intrinsic fluorescence, and fluorescence of the Nile red dye bound to OCP. It was demonstrated that all of these three methods provide the same kinetic parameters of the photocycle, namely, the kinetics of OCP relaxation in darkness was biexponential with a ratio of two components equal to 2:1 independently of temperature. Whereas the changes of the absorption spectrum of OCP characterize the geometry and environment of its chromophore, the intrinsic fluorescence of OCP reveals changes in its tertiary structure, and the fluorescence properties of Nile red indicate the exposure of hydrophobic surface areas of OCP to the solvent following the photocycle. The results of molecular-dynamics studies indicated the presence of two metastable conformations of 3′-hydroxyechinenone, which is consistent with characteristic changes in the Raman spectra. We conclude that rotation of the β-ionylidene ring in the C-terminal domain of OCP could be one of the first conformational rearrangements that occur during photoactivation. The obtained results suggest that the photoactivated form of OCP represents a molten globule-like state that is characterized by increased mobility of tertiary structure elements and solvent accessibility. PMID:26244741

  10. Update: Influenza Activity - United States.

    PubMed

    Smith, Sophie; Blanton, Lenee; Kniss, Krista; Mustaquim, Desiree; Steffens, Craig; Reed, Carrie; Bramley, Anna; Flannery, Brendan; Fry, Alicia M; Grohskopf, Lisa A; Bresee, Joseph; Wallis, Teresa; Garten, Rebecca; Xu, Xiyan; Elal, Anwar Isa Abd; Gubareva, Larisa; Barnes, John; Wentworth, David E; Burns, Erin; Katz, Jacqueline; Jernigan, Daniel; Brammer, Lynnette

    2015-12-11

    CDC collects, compiles, and analyzes data on influenza activity year-round in the United States. The influenza season generally begins in the fall and continues through the winter and spring months; however, the timing and severity of circulating influenza viruses can vary by geographic location and season. Influenza activity in the United States remained low through October and November in 2015. Influenza A viruses have been most frequently identified, with influenza A (H3) viruses predominating. This report summarizes U.S. influenza activity for the period October 4-November 28, 2015. PMID:26656182

  11. Sleep Loss Activates Cellular Inflammatory Signaling

    PubMed Central

    Irwin, Michael R.; Wang, Minge; Ribeiro, Denise; Cho, Hyong Jin; Olmstead, Richard; Breen, Elizabeth Crabb; Martinez-Maza, Otoniel; Cole, Steve

    2008-01-01

    Background Accumulating evidence suggests that sleep disturbance is associated with inflammation and related disorders including cardiovascular disease, arthritis, and diabetes mellitus. This study was undertaken to test the effects of sleep loss on activation of nuclear factor (NF) -κB, a transcription factor that serves a critical role in the inflammatory signaling cascade. Methods In 14 healthy adults (7 females; 7 males), peripheral blood mononuclear cell NF-κB was repeatedly assessed, along with enumeration of lymphocyte subpopulations, in the morning after baseline sleep, partial sleep deprivation (awake from 23:00 h to 03:00 h), and recovery sleep. Results In the morning after a night of sleep loss, mononuclear cell NF-κB activation was significantly greater compared with morning levels following uninterrupted baseline or recovery sleep, in which the response was found in females but not in males. Conclusions These results identify NF-κB activation as a molecular pathway by which sleep disturbance may influence leukocyte inflammatory gene expression and the risk of inflammation-related disease. PMID:18561896

  12. Active voltammetric microsensors with neural signal processing.

    SciTech Connect

    Vogt, M. C.

    1998-12-11

    Many industrial and environmental processes, including bioremediation, would benefit from the feedback and control information provided by a local multi-analyte chemical sensor. For most processes, such a sensor would need to be rugged enough to be placed in situ for long-term remote monitoring, and inexpensive enough to be fielded in useful numbers. The multi-analyte capability is difficult to obtain from common passive sensors, but can be provided by an active device that produces a spectrum-type response. Such new active gas microsensor technology has been developed at Argonne National Laboratory. The technology couples an electrocatalytic ceramic-metallic (cermet) microsensor with a voltammetric measurement technique and advanced neural signal processing. It has been demonstrated to be flexible, rugged, and very economical to produce and deploy. Both narrow interest detectors and wide spectrum instruments have been developed around this technology. Much of this technology's strength lies in the active measurement technique employed. The technique involves applying voltammetry to a miniature electrocatalytic cell to produce unique chemical ''signatures'' from the analytes. These signatures are processed with neural pattern recognition algorithms to identify and quantify the components in the analyte. The neural signal processing allows for innovative sampling and analysis strategies to be employed with the microsensor. In most situations, the whole response signature from the voltammogram can be used to identify, classify, and quantify an analyte, without dissecting it into component parts. This allows an instrument to be calibrated once for a specific gas or mixture of gases by simple exposure to a multi-component standard rather than by a series of individual gases. The sampled unknown analytes can vary in composition or in concentration, the calibration, sensing, and processing methods of these active voltammetric microsensors can detect, recognize, and

  13. Robust Indoor Human Activity Recognition Using Wireless Signals.

    PubMed

    Wang, Yi; Jiang, Xinli; Cao, Rongyu; Wang, Xiyang

    2015-01-01

    Wireless signals-based activity detection and recognition technology may be complementary to the existing vision-based methods, especially under the circumstance of occlusions, viewpoint change, complex background, lighting condition change, and so on. This paper explores the properties of the channel state information (CSI) of Wi-Fi signals, and presents a robust indoor daily human activity recognition framework with only one pair of transmission points (TP) and access points (AP). First of all, some indoor human actions are selected as primitive actions forming a training set. Then, an online filtering method is designed to make actions' CSI curves smooth and allow them to contain enough pattern information. Each primitive action pattern can be segmented from the outliers of its multi-input multi-output (MIMO) signals by a proposed segmentation method. Lastly, in online activities recognition, by selecting proper features and Support Vector Machine (SVM) based multi-classification, activities constituted by primitive actions can be recognized insensitive to the locations, orientations, and speeds. PMID:26184231

  14. Regulators of G-protein signaling accelerate GPCR signaling kinetics and govern sensitivity solely by accelerating GTPase activity.

    PubMed

    Lambert, Nevin A; Johnston, Christopher A; Cappell, Steven D; Kuravi, Sudhakiranmayi; Kimple, Adam J; Willard, Francis S; Siderovski, David P

    2010-04-13

    G-protein heterotrimers, composed of a guanine nucleotide-binding G alpha subunit and an obligate G betagamma dimer, regulate signal transduction pathways by cycling between GDP- and GTP-bound states. Signal deactivation is achieved by G alpha-mediated GTP hydrolysis (GTPase activity) which is enhanced by the GTPase-accelerating protein (GAP) activity of "regulator of G-protein signaling" (RGS) proteins. In a cellular context, RGS proteins have also been shown to speed up the onset of signaling, and to accelerate deactivation without changing amplitude or sensitivity of the signal. This latter paradoxical activity has been variably attributed to GAP/enzymatic or non-GAP/scaffolding functions of these proteins. Here, we validated and exploited a G alpha switch-region point mutation, known to engender increased GTPase activity, to mimic in cis the GAP function of RGS proteins. While the transition-state, GDP x AlF(4)(-)-bound conformation of the G202A mutant was found to be nearly identical to wild-type, G alpha(i1)(G202A) x GDP assumed a divergent conformation more closely resembling the GDP x AlF(4)(-)-bound state. When placed within Saccharomyces cerevisiae G alpha subunit Gpa1, the fast-hydrolysis mutation restored appropriate dose-response behaviors to pheromone signaling in the absence of RGS-mediated GAP activity. A bioluminescence resonance energy transfer (BRET) readout of heterotrimer activation with high temporal resolution revealed that fast intrinsic GTPase activity could recapitulate in cis the kinetic sharpening (increased onset and deactivation rates) and blunting of sensitivity also engendered by RGS protein action in trans. Thus G alpha-directed GAP activity, the first biochemical function ascribed to RGS proteins, is sufficient to explain the activation kinetics and agonist sensitivity observed from G-protein-coupled receptor (GPCR) signaling in a cellular context. PMID:20351284

  15. Method of machine technical state assessment on the basis of joint signal analysis

    NASA Astrophysics Data System (ADS)

    Fidali, Marek

    2011-04-01

    Joint analysis of two signals which are observed during machine operation allows us to acquire information on such phenomena occurring within the machine which cannot be obtained as the results of an analysis of single signals. This knowledge makes it purposeful to assume that the joint analysis of a major number of signals allows us also to acquire new information on the machine state. In this paper the concept of joint signal analysis based on a signal analysis in both "micro" and "macro" time domains was described. In order to calculate values of joint features of signals and determine the machine state on the basis of the joint analysis results the generalized data window was introduced. In order to limit a number of simultaneously considered signals and determine a relation between signal feature values and machine states, the procedure based on an application of additional virtual signals was proposed. In order to verify the elaborated method an active diagnostic experiment was carried out. The experiment result was a set of learning data, which enables us to construct a diagnostic classifier. Exemplary results of classification of technical state of a machine were also presented.

  16. New Constitutively Active Phytochromes Exhibit Light-Independent Signaling Activity.

    PubMed

    Jeong, A-Reum; Lee, Si-Seok; Han, Yun-Jeong; Shin, Ah-Young; Baek, Ayoung; Ahn, Taeho; Kim, Min-Gon; Kim, Young Soon; Lee, Keun Woo; Nagatani, Akira; Kim, Jeong-Il

    2016-08-01

    Plant phytochromes are photoreceptors that mediate a variety of photomorphogenic responses. There are two spectral photoisomers, the red light-absorbing Pr and far-red light-absorbing Pfr forms, and the photoreversible transformation between the two forms is important for the functioning of phytochromes. In this study, we isolated a Tyr-268-to-Val mutant of Avena sativa phytochrome A (AsYVA) that displayed little photoconversion. Interestingly, transgenic plants of AsYVA showed light-independent phytochrome signaling with a constitutive photomorphogenic (cop) phenotype that is characterized by shortened hypocotyls and open cotyledons in the dark. In addition, the corresponding Tyr-303-to-Val mutant of Arabidopsis (Arabidopsis thaliana) phytochrome B (AtYVB) exhibited nuclear localization and interaction with phytochrome-interacting factor 3 (PIF3) independently of light, conferring a constitutive photomorphogenic development to its transgenic plants, which is comparable to the first constitutively active version of phytochrome B (YHB; Tyr-276-to-His mutant). We also found that chromophore ligation was required for the light-independent interaction of AtYVB with PIF3. Moreover, we demonstrated that AtYVB did not exhibit phytochrome B activity when it was localized in the cytosol by fusion with the nuclear export signal and that AsYVA exhibited the full activity of phytochrome A when localized in the nucleus by fusion with the nuclear localization signal. Furthermore, the corresponding Tyr-269-to-Val mutant of Arabidopsis phytochrome A (AtYVA) exhibited similar cop phenotypes in transgenic plants to AsYVA. Collectively, these results suggest that the conserved Tyr residues in the chromophore-binding pocket play an important role during the Pr-to-Pfr photoconversion of phytochromes, providing new constitutively active alleles of phytochromes by the Tyr-to-Val mutation. PMID:27325667

  17. Signal integration by Ca2+ regulates intestinal stem cell activity

    PubMed Central

    Deng, Hansong; Gerencser, Akos A.; Jasper, Heinrich

    2015-01-01

    Summary Somatic stem cells (SCs) maintain tissue homeostasis by dynamically adjusting proliferation and differentiation in response to stress and metabolic cues. Here, we identify Ca2+ signaling as a central regulator of intestinal SC (ISC) activity in Drosophila. We find that dietary L-glutamate stimulates ISC division and gut growth. The metabotropic glutamate receptor (mGluR) is required in ISCs for this response and for an associated modulation of cytosolic Ca2+ oscillations that results in sustained high cytosolic Ca2+ concentrations. High cytosolic Ca2+ induces ISC proliferation by regulating Calcineurin and CREB - regulated transcriptional co-activator (CRTC). In response to a wide range of dietary and stress stimuli, ISCs reversibly transition between Ca2+ oscillation states that represent poised or activated modes of proliferation, respectively. We propose that the dynamic regulation of intracellular Ca2+ levels allows effective integration of diverse mitogenic signals in ISCs to tailor their proliferative activity to the needs of the tissue. PMID:26633624

  18. Robust Indoor Human Activity Recognition Using Wireless Signals

    PubMed Central

    Wang, Yi; Jiang, Xinli; Cao, Rongyu; Wang, Xiyang

    2015-01-01

    Wireless signals–based activity detection and recognition technology may be complementary to the existing vision-based methods, especially under the circumstance of occlusions, viewpoint change, complex background, lighting condition change, and so on. This paper explores the properties of the channel state information (CSI) of Wi-Fi signals, and presents a robust indoor daily human activity recognition framework with only one pair of transmission points (TP) and access points (AP). First of all, some indoor human actions are selected as primitive actions forming a training set. Then, an online filtering method is designed to make actions’ CSI curves smooth and allow them to contain enough pattern information. Each primitive action pattern can be segmented from the outliers of its multi-input multi-output (MIMO) signals by a proposed segmentation method. Lastly, in online activities recognition, by selecting proper features and Support Vector Machine (SVM) based multi-classification, activities constituted by primitive actions can be recognized insensitive to the locations, orientations, and speeds. PMID:26184231

  19. Kinase active Misshapen regulates Notch signaling in Drosophila melanogaster.

    PubMed

    Mishra, Abhinava K; Sachan, Nalani; Mutsuddi, Mousumi; Mukherjee, Ashim

    2015-11-15

    Notch signaling pathway represents a principal cellular communication system that plays a pivotal role during development of metazoans. Drosophila misshapen (msn) encodes a protein kinase, which is related to the budding yeast Ste20p (sterile 20 protein) kinase. In a genetic screen, using candidate gene approach to identify novel kinases involved in Notch signaling, we identified msn as a novel regulator of Notch signaling. Data presented here suggest that overexpression of kinase active form of Msn exhibits phenotypes similar to Notch loss-of-function condition and msn genetically interacts with components of Notch signaling pathway. Kinase active form of Msn associates with Notch receptor and regulate its signaling activity. We further show that kinase active Misshapen leads to accumulation of membrane-tethered form of Notch. Moreover, activated Msn also depletes Armadillo and DE-Cadherin from adherens junctions. Thus, this study provides a yet unknown mode of regulation of Notch signaling by Misshapen. PMID:26431585

  20. Parallel states of pathological Wnt signaling in neonatal brain injury and colon cancer.

    PubMed

    Fancy, Stephen P J; Harrington, Emily P; Baranzini, Sergio E; Silbereis, John C; Shiow, Lawrence R; Yuen, Tracy J; Huang, Eric J; Lomvardas, Stavros; Rowitch, David H

    2014-04-01

    In colon cancer, mutation of the Wnt repressor APC (encoding adenomatous polyposis coli) leads to a state of aberrant and unrestricted high-activity signaling. However, the relevance of high Wnt tone in non-genetic human disease is unknown. Here we demonstrate that distinct functional states of Wnt activity determine oligodendrocyte precursor cell (OPC) differentiation and myelination. Mouse OPCs with genetic Wnt dysregulation (high tone) express multiple genes in common with colon cancer, including Lef1, Sp5, Ets2, Rnf43 and Dusp4. Surprisingly, we found that OPCs in lesions of hypoxic human neonatal white matter injury upregulated markers of high Wnt activity and lacked expression of APC. We also found that lack of Wnt repressor tone promoted permanent white matter injury after mild hypoxic insult. These findings suggest a state of pathological high-activity Wnt signaling in human disease tissues that lack predisposing genetic mutation. PMID:24609463

  1. Insulin Receptor Signaling in Normal and Insulin-Resistant States

    PubMed Central

    Boucher, Jérémie; Kleinridders, André; Kahn, C. Ronald

    2014-01-01

    In the wake of the worldwide increase in type-2 diabetes, a major focus of research is understanding the signaling pathways impacting this disease. Insulin signaling regulates glucose, lipid, and energy homeostasis, predominantly via action on liver, skeletal muscle, and adipose tissue. Precise modulation of this pathway is vital for adaption as the individual moves from the fed to the fasted state. The positive and negative modulators acting on different steps of the signaling pathway, as well as the diversity of protein isoform interaction, ensure a proper and coordinated biological response to insulin in different tissues. Whereas genetic mutations are causes of rare and severe insulin resistance, obesity can lead to insulin resistance through a variety of mechanisms. Understanding these pathways is essential for development of new drugs to treat diabetes, metabolic syndrome, and their complications. PMID:24384568

  2. Human ECG signal parameters estimation during controlled physical activity

    NASA Astrophysics Data System (ADS)

    Maciejewski, Marcin; Surtel, Wojciech; Dzida, Grzegorz

    2015-09-01

    ECG signal parameters are commonly used indicators of human health condition. In most cases the patient should remain stationary during the examination to decrease the influence of muscle artifacts. During physical activity, the noise level increases significantly. The ECG signals were acquired during controlled physical activity on a stationary bicycle and during rest. Afterwards, the signals were processed using a method based on Pan-Tompkins algorithms to estimate their parameters and to test the method.

  3. State Transitions in the TORC1 Signaling Pathway and Information Processing in Saccharomyces cerevisiae

    PubMed Central

    Hughes Hallett, James E.; Luo, Xiangxia; Capaldi, Andrew P.

    2014-01-01

    TOR kinase complex I (TORC1) is a key regulator of cell growth and metabolism in all eukaryotes. Previous studies in yeast have shown that three GTPases—Gtr1, Gtr2, and Rho1—bind to TORC1 in nitrogen and amino acid starvation conditions to block phosphorylation of the S6 kinase Sch9 and activate protein phosphatase 2A (PP2A). This leads to downregulation of 450 Sch9-dependent protein and ribosome synthesis genes and upregulation of 100 PP2A-dependent nitrogen assimilation and amino acid synthesis genes. Here, using bandshift assays and microarray measurements, we show that the TORC1 pathway also populates three other stress/starvation states. First, in glucose starvation conditions, the AMP-activated protein kinase (AMPK/Snf1) and at least one other factor push the TORC1 pathway into an off state, in which Sch9-branch signaling and PP2A-branch signaling are both inhibited. Remarkably, the TORC1 pathway remains in the glucose starvation (PP2A inhibited) state even when cells are simultaneously starved for nitrogen and glucose. Second, in osmotic stress, the MAPK Hog1/p38 drives the TORC1 pathway into a different state, in which Sch9 signaling and PP2A-branch signaling are inhibited, but PP2A-branch signaling can still be activated by nitrogen starvation. Third, in oxidative stress and heat stress, TORC1-Sch9 signaling is blocked while weak PP2A-branch signaling occurs. Together, our data show that the TORC1 pathway acts as an information-processing hub, activating different genes in different conditions to ensure that available energy is allocated to drive growth, amino acid synthesis, or a stress response, depending on the needs of the cell. PMID:25085507

  4. Free energy landscape of activation in a signalling protein at atomic resolution

    NASA Astrophysics Data System (ADS)

    Pontiggia, F.; Pachov, D. V.; Clarkson, M. W.; Villali, J.; Hagan, M. F.; Pande, V. S.; Kern, D.

    2015-06-01

    The interconversion between inactive and active protein states, traditionally described by two static structures, is at the heart of signalling. However, how folded states interconvert is largely unknown due to the inability to experimentally observe transition pathways. Here we explore the free energy landscape of the bacterial response regulator NtrC by combining computation and nuclear magnetic resonance, and discover unexpected features underlying efficient signalling. We find that functional states are defined purely in kinetic and not structural terms. The need of a well-defined conformer, crucial to the active state, is absent in the inactive state, which comprises a heterogeneous collection of conformers. The transition between active and inactive states occurs through multiple pathways, facilitated by a number of nonnative transient hydrogen bonds, thus lowering the transition barrier through both entropic and enthalpic contributions. These findings may represent general features for functional conformational transitions within the folded state.

  5. 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.

  6. The satiety signaling neuropeptide perisulfakinin inhibits the activity of central neurons promoting general activity.

    PubMed

    Wicher, Dieter; Derst, Christian; Gautier, Hélène; Lapied, Bruno; Heinemann, Stefan H; Agricola, Hans-Jürgen

    2007-01-01

    The metabolic state is one of the determinants of the general activity level. Satiety is related to resting or sleep whereas hunger correlates to wakefulness and activity. The counterpart to the mammalian satiety signal cholecystokinin (CCK) in insects are the sulfakinins. The aim of this study was to resolve the mechanism by which the antifeedant activity of perisulfakinin (PSK) in Periplaneta americana is mediated. We identified the sources of PSK which is used both as hormone and as paracrine messenger. PSK is found in the neurohemal organ of the brain and in nerve endings throughout the central nervous system. To correlate the distributions of PSK and its receptor (PSKR), we cloned the gene coding for PSKR and provide evidence for its expression within the nervous system. It occurs only in a few neurons, among them are the dorsal unpaired median (DUM) neurons which release octopamine thereby regulating the general level of activity. Application of PSK to DUM neurons attenuated the spiking frequency (EC(50)=11pM) due to reduction of a pacemaker Ca(2+) current through cAMP-inhibited pTRPgamma channels. PSK increased the intracellular cAMP level while decreasing the intracellular Ca(2+) concentration in DUM neurons. Thus, the satiety signal conferred by PSK acts antagonistically to the hunger signal, provided by the adipokinetic hormone (AKH): PSK depresses the electrical activity of DUM neurons by inhibiting the pTRPgamma channel that is activated by AKH under conditions of food shortage. PMID:18946521

  7. The Satiety Signaling Neuropeptide Perisulfakinin Inhibits the Activity of Central Neurons Promoting General Activity

    PubMed Central

    Wicher, Dieter; Derst, Christian; Gautier, Hélène; Lapied, Bruno; Heinemann, Stefan H.; Agricola, Hans-Jürgen

    2007-01-01

    The metabolic state is one of the determinants of the general activity level. Satiety is related to resting or sleep whereas hunger correlates to wakefulness and activity. The counterpart to the mammalian satiety signal cholecystokinin (CCK) in insects are the sulfakinins. The aim of this study was to resolve the mechanism by which the antifeedant activity of perisulfakinin (PSK) in Periplaneta americana is mediated. We identified the sources of PSK which is used both as hormone and as paracrine messenger. PSK is found in the neurohemal organ of the brain and in nerve endings throughout the central nervous system. To correlate the distributions of PSK and its receptor (PSKR), we cloned the gene coding for PSKR and provide evidence for its expression within the nervous system. It occurs only in a few neurons, among them are the dorsal unpaired median (DUM) neurons which release octopamine thereby regulating the general level of activity. Application of PSK to DUM neurons attenuated the spiking frequency (EC50=11pM) due to reduction of a pacemaker Ca2+ current through cAMP-inhibited pTRPγ channels. PSK increased the intracellular cAMP level while decreasing the intracellular Ca2+ concentration in DUM neurons. Thus, the satiety signal conferred by PSK acts antagonistically to the hunger signal, provided by the adipokinetic hormone (AKH): PSK depresses the electrical activity of DUM neurons by inhibiting the pTRPγ channel that is activated by AKH under conditions of food shortage. PMID:18946521

  8. The mobility of two kinase domains in the Escherichia coli chemoreceptor array varies with signaling state

    PubMed Central

    Briegel, Ariane; Ames, Peter; Gumbart, James C.; Oikonomou, Catherine M.; Parkinson, John S.; Jensen, Grant J.

    2013-01-01

    Summary Motile bacteria sense their physical and chemical environment through highly cooperative, ordered arrays of chemoreceptors. These signaling complexes phosphorylate a response regulator which in turn governs flagellar motor reversals, driving cells towards favorable environments. The structural changes that translate chemoeffector binding into the appropriate kinase output are not known. Here, we apply high-resolution electron cryotomography to visualize mutant chemoreceptor signaling arrays in well-defined kinase activity states. The arrays were well ordered in all signaling states, with no discernible differences in receptor conformation at 2-3 nm resolution. Differences were observed, however, in a keel-like density that we identify here as CheA kinase domains P1 and P2, which are the phosphorylation site domain and the binding domain for response regulator target proteins, respectively. Mutant receptor arrays with high kinase activities all exhibited small keels and high proteolysis susceptibility, indicative of mobile P1 and P2 domains. In contrast, arrays in kinase-off signaling states exhibited a range of keel sizes. These findings confirm that chemoreceptor arrays do not undergo large structural changes during signaling, and suggest instead that kinase activity is modulated at least in part by changes in the mobility of key domains. PMID:23802570

  9. The Canonical Notch Signaling Pathway: Unfolding the Activation Mechanism

    PubMed Central

    Kopan, Raphael; Ilagan, Ma. Xenia G.

    2009-01-01

    Notch signaling regulates many aspects of metazoan development and tissue renewal. Accordingly, misregulation or loss of Notch signaling underlies multiple human disorders, from developmental syndromes to adult onset diseases and cancer. Notch receptor activation is irreversible as it involves proteolysis-mediated release of the Notch intracellular domain, translocation to the nucleus, and association with a DNA-bound protein. Even though each Notch molecule signals only once without amplification by secondary messenger cascades, Notch signaling is remarkably robust in most tissues. In this review, we highlight the recent studies that reveal new molecular details involved in regulating ligand-mediated activation, receptor proteolysis and target selection. PMID:19379690

  10. Multiscale Approach to the Determination of the Photoactive Yellow Protein Signaling State Ensemble

    PubMed Central

    A. Rohrdanz, Mary; Zheng, Wenwei; Lambeth, Bradley; Vreede, Jocelyne; Clementi, Cecilia

    2014-01-01

    The nature of the optical cycle of photoactive yellow protein (PYP) makes its elucidation challenging for both experiment and theory. The long transition times render conventional simulation methods ineffective, and yet the short signaling-state lifetime makes experimental data difficult to obtain and interpret. Here, through an innovative combination of computational methods, a prediction and analysis of the biological signaling state of PYP is presented. Coarse-grained modeling and locally scaled diffusion map are first used to obtain a rough bird's-eye view of the free energy landscape of photo-activated PYP. Then all-atom reconstruction, followed by an enhanced sampling scheme; diffusion map-directed-molecular dynamics are used to focus in on the signaling-state region of configuration space and obtain an ensemble of signaling state structures. To the best of our knowledge, this is the first time an all-atom reconstruction from a coarse grained model has been performed in a relatively unexplored region of molecular configuration space. We compare our signaling state prediction with previous computational and more recent experimental results, and the comparison is favorable, which validates the method presented. This approach provides additional insight to understand the PYP photo cycle, and can be applied to other systems for which more direct methods are impractical. PMID:25356903

  11. Wnt Signaling in Neurogenesis during Aging and Physical Activity

    PubMed Central

    Chen, Michael; Do, Huong

    2012-01-01

    Over the past decade, much progress has been made regarding our understanding of neurogenesis in both young and old animals and where it occurs throughout the lifespan, although the growth of new neurons declines with increasing age. In addition, physical activity can reverse this age-dependent decline in neurogenesis. Highly correlated with this decline is the degree of inter and intracellular Wnt signaling, the molecular mechanisms of which have only recently started to be elucidated. So far, most of what we know about intracellular signaling during/following exercise centers around the CREB/CRE initiated transcriptional events. Relatively little is known, however, about how aging and physical activity affect the Wnt signaling pathway. Herein, we briefly review the salient features of neurogenesis in young and then in old adult animals. Then, we discuss Wnt signaling and review the very few in vitro and in vivo studies that have examined the Wnt signaling pathways in aging and physical activity. PMID:24961268

  12. Cellular Cholesterol Directly Activates Smoothened in Hedgehog Signaling.

    PubMed

    Huang, Pengxiang; Nedelcu, Daniel; Watanabe, Miyako; Jao, Cindy; Kim, Youngchang; Liu, Jing; Salic, Adrian

    2016-08-25

    In vertebrates, sterols are necessary for Hedgehog signaling, a pathway critical in embryogenesis and cancer. Sterols activate the membrane protein Smoothened by binding its extracellular, cysteine-rich domain (CRD). Major unanswered questions concern the nature of the endogenous, activating sterol and the mechanism by which it regulates Smoothened. We report crystal structures of CRD complexed with sterols and alone, revealing that sterols induce a dramatic conformational change of the binding site, which is sufficient for Smoothened activation and is unique among CRD-containing receptors. We demonstrate that Hedgehog signaling requires sterol binding to Smoothened and define key residues for sterol recognition and activity. We also show that cholesterol itself binds and activates Smoothened. Furthermore, the effect of oxysterols is abolished in Smoothened mutants that retain activation by cholesterol and Hedgehog. We propose that the endogenous Smoothened activator is cholesterol, not oxysterols, and that vertebrate Hedgehog signaling controls Smoothened by regulating its access to cholesterol. PMID:27545348

  13. Activation of endothelial β-catenin signaling induces heart failure

    PubMed Central

    Nakagawa, Akito; Naito, Atsuhiko T.; Sumida, Tomokazu; Nomura, Seitaro; Shibamoto, Masato; Higo, Tomoaki; Okada, Katsuki; Sakai, Taku; Hashimoto, Akihito; Kuramoto, Yuki; Oka, Toru; Lee, Jong-Kook; Harada, Mutsuo; Ueda, Kazutaka; Shiojima, Ichiro; Limbourg, Florian P.; Adams, Ralf H.; Noda, Tetsuo; Sakata, Yasushi; Akazawa, Hiroshi; Komuro, Issei

    2016-01-01

    Activation of β-catenin-dependent canonical Wnt signaling in endothelial cells plays a key role in angiogenesis during development and ischemic diseases, however, other roles of Wnt/β-catenin signaling in endothelial cells remain poorly understood. Here, we report that sustained activation of β-catenin signaling in endothelial cells causes cardiac dysfunction through suppressing neuregulin-ErbB pathway in the heart. Conditional gain-of-function mutation of β-catenin, which activates Wnt/β-catenin signaling in Bmx-positive arterial endothelial cells (Bmx/CA mice) led to progressive cardiac dysfunction and 100% mortality at 40 weeks after tamoxifen treatment. Electron microscopic analysis revealed dilatation of T-tubules and degeneration of mitochondria in cardiomyocytes of Bmx/CA mice, which are similar to the changes observed in mice with decreased neuregulin-ErbB signaling. Endothelial expression of Nrg1 and cardiac ErbB signaling were suppressed in Bmx/CA mice. The cardiac dysfunction of Bmx/CA mice was ameliorated by administration of recombinant neuregulin protein. These results collectively suggest that sustained activation of Wnt/β-catenin signaling in endothelial cells might be a cause of heart failure through suppressing neuregulin-ErbB signaling, and that the Wnt/β-catenin/NRG axis in cardiac endothelial cells might become a therapeutic target for heart failure. PMID:27146149

  14. Activation of endothelial β-catenin signaling induces heart failure.

    PubMed

    Nakagawa, Akito; Naito, Atsuhiko T; Sumida, Tomokazu; Nomura, Seitaro; Shibamoto, Masato; Higo, Tomoaki; Okada, Katsuki; Sakai, Taku; Hashimoto, Akihito; Kuramoto, Yuki; Oka, Toru; Lee, Jong-Kook; Harada, Mutsuo; Ueda, Kazutaka; Shiojima, Ichiro; Limbourg, Florian P; Adams, Ralf H; Noda, Tetsuo; Sakata, Yasushi; Akazawa, Hiroshi; Komuro, Issei

    2016-01-01

    Activation of β-catenin-dependent canonical Wnt signaling in endothelial cells plays a key role in angiogenesis during development and ischemic diseases, however, other roles of Wnt/β-catenin signaling in endothelial cells remain poorly understood. Here, we report that sustained activation of β-catenin signaling in endothelial cells causes cardiac dysfunction through suppressing neuregulin-ErbB pathway in the heart. Conditional gain-of-function mutation of β-catenin, which activates Wnt/β-catenin signaling in Bmx-positive arterial endothelial cells (Bmx/CA mice) led to progressive cardiac dysfunction and 100% mortality at 40 weeks after tamoxifen treatment. Electron microscopic analysis revealed dilatation of T-tubules and degeneration of mitochondria in cardiomyocytes of Bmx/CA mice, which are similar to the changes observed in mice with decreased neuregulin-ErbB signaling. Endothelial expression of Nrg1 and cardiac ErbB signaling were suppressed in Bmx/CA mice. The cardiac dysfunction of Bmx/CA mice was ameliorated by administration of recombinant neuregulin protein. These results collectively suggest that sustained activation of Wnt/β-catenin signaling in endothelial cells might be a cause of heart failure through suppressing neuregulin-ErbB signaling, and that the Wnt/β-catenin/NRG axis in cardiac endothelial cells might become a therapeutic target for heart failure. PMID:27146149

  15. THE STATE TOBACCO ACTIVITIES TRACKING AND EVALUATION (STATE) SYSTEM

    EPA Science Inventory

    The State Tobacco Activities Tracking and Evaluation (STATE) System is an electronic data warehouse containing up-to-date and historical state-level data on tobacco use prevention and control. The STATE System is designed to integrate many data sources to provide comprehensive su...

  16. Quantifying bursting neuron activity from calcium signals using blind deconvolution.

    PubMed

    Park, In Jun; Bobkov, Yuriy V; Ache, Barry W; Principe, Jose C

    2013-09-15

    Advances in calcium imaging have enabled studies of the dynamic activity of both individual neurons and neuronal assemblies. However, challenges, such as unknown nonlinearities in the spike-calcium relationship, noise, and the often relatively low temporal resolution of the calcium signal compared to the time-scale of spike generation, restrict the accurate estimation of action potentials from the calcium signal. Complex neuronal discharge, such as the activity demonstrated by bursting and rhythmically active neurons, represents an even greater challenge for reconstructing spike trains based on calcium signals. We propose a method using blind calcium signal deconvolution based on an information-theoretic approach. This model is meant to maximise the output entropy of a nonlinear filter where the nonlinearity is defined by the cumulative distribution function of the spike signal. We tested our maximum entropy (ME) algorithm using bursting olfactory receptor neurons (bORNs) of the lobster olfactory organ. The advantage of the ME algorithm is that the filter can be trained online based only on the statistics of the spike signal, without any assumptions regarding the unknown transfer function characterizing the relation between the spike and calcium signal. We show that the ME method is able to more accurately reconstruct the timing of the first and last spikes of a burst compared to other methods and that it improves the temporal precision fivefold compared to direct timing resolution of calcium signal. PMID:23711821

  17. Activation of Notch-Mediated Protective Signaling in the Myocardium

    PubMed Central

    Gude, Natalie A.; Emmanuel, Gregory; Wu, Weitao; Cottage, Christopher T.; Fischer, Kimberlee; Quijada, Pearl; Muraski, John A.; Alvarez, Roberto; Rubio, Marta; Schaefer, Eric; Sussman, Mark A.

    2013-01-01

    The Notch network regulates multiple cellular processes, including cell fate determination, development, differentiation, proliferation, apoptosis, and regeneration. These processes are regulated via Notch-mediated activity that involves hepatocyte growth factor (HGF)/c-Met receptor and phosphatidylinositol 3-kinase/Akt signaling cascades. The impact of HGF on Notch signaling was assessed following myocardial infarction as well as in cultured cardiomyocytes. Notch1 is activated in border zone cardiomyocytes coincident with nuclear c-Met following infarction. Intramyocardial injection of HGF enhances Notch1 and Akt activation in adult mouse myocardium. Corroborating evidence in cultured cardiomyocytes shows treatment with HGF or insulin increases levels of Notch effector Hes1 in immunoblots, whereas overexpression of activated Notch intracellular domain prompts a 3-fold increase in phosphorylated Akt. Infarcted hearts injected with adenoviral vector expressing Notch intracellular domain treatment exhibit improved hemodynamic function in comparison with control mice after 4 weeks, implicating Notch signaling in a cardioprotective role following cardiac injury. These results indicate Notch activation in cardiomyocytes is mediated through c-Met and Akt survival signaling pathways, and Notch1 signaling in turn enhances Akt activity. This mutually supportive crosstalk suggests a positive survival feedback mechanism between Notch and Akt signaling in adult myocardium following injury. PMID:18369158

  18. Endocytosis of Seven-Transmembrane RGS Protein Activates G- protein Coupled Signaling in Arabidopsis

    PubMed Central

    Urano, Daisuke; Phan, Nguyen; Jones, Janice C.; Yang, Jing; Huang, Jirong; Grigston, Jeffrey; Taylor, J. Philip; Jones, Alan M.

    2012-01-01

    Signal transduction typically begins by ligand-dependent activation of a concomitant partner which is otherwise in its resting state. However, in cases where signal activation is constitutive by default, the mechanism of regulation is unknown. The Arabidopsis thaliana heterotrimeric Gα protein self-activates without accessory proteins, and is kept in its resting state by the negative regulator, AtRGS1 (Regulator of G protein Signaling 1), which is the prototype of a seven transmembrane receptor fused with an RGS domain. Endocytosis of AtRGS1 by ligand-dependent endocytosis physically uncouples the GTPase accelerating activity of AtRGS1 from the Gα protein, permitting sustained activation. Phosphorylation of AtRGS1 by AtWNK8 kinase causes AtRGS1 endocytosis, required both for G protein-mediated sugar signaling and cell proliferation. In animals, receptor endocytosis results in signal desensitization, whereas in plants, endocytosis results in signal activation. These findings reveal how different organisms rearrange a regulatory system to result in opposite outcomes using similar phosphorylation-dependent endocytosis. PMID:22940907

  19. Cell-Autonomous Gβ Signaling Defines Neuron-Specific Steady State Serotonin Synthesis in Caenorhabditis elegans

    PubMed Central

    Xu, Lu; Choi, Sunju; Xie, Yusu; Sze, Ji Ying

    2015-01-01

    Heterotrimeric G proteins regulate a vast array of cellular functions via specific intracellular effectors. Accumulating pharmacological and biochemical studies implicate Gβ subunits as signaling molecules interacting directly with a wide range of effectors to modulate downstream cellular responses, in addition to their role in regulating Gα subunit activities. However, the native biological roles of Gβ-mediated signaling pathways in vivo have been characterized only in a few cases. Here, we identified a Gβ GPB-1 signaling pathway operating in specific serotonergic neurons to the define steady state serotonin (5-HT) synthesis, through a genetic screen for 5-HT synthesis mutants in Caenorhabditis elegans. We found that signaling through cell autonomous GPB-1 to the OCR-2 TRPV channel defines the baseline expression of 5-HT synthesis enzyme tryptophan hydroxylase tph-1 in ADF chemosensory neurons. This Gβ signaling pathway is not essential for establishing the serotonergic cell fates and is mechanistically separated from stress-induced tph-1 upregulation. We identified that ADF-produced 5-HT controls specific innate rhythmic behaviors. These results revealed a Gβ-mediated signaling operating in differentiated cells to specify intrinsic functional properties, and indicate that baseline TPH expression is not a default generic serotonergic fate, but is programmed in a cell-specific manner in the mature nervous system. Cell-specific regulation of TPH expression could be a general principle for tailored steady state 5-HT synthesis in functionally distinct neurons and their regulation of innate behavior. PMID:26402365

  20. Cell-Autonomous Gβ Signaling Defines Neuron-Specific Steady State Serotonin Synthesis in Caenorhabditis elegans.

    PubMed

    Xu, Lu; Choi, Sunju; Xie, Yusu; Sze, Ji Ying

    2015-09-01

    Heterotrimeric G proteins regulate a vast array of cellular functions via specific intracellular effectors. Accumulating pharmacological and biochemical studies implicate Gβ subunits as signaling molecules interacting directly with a wide range of effectors to modulate downstream cellular responses, in addition to their role in regulating Gα subunit activities. However, the native biological roles of Gβ-mediated signaling pathways in vivo have been characterized only in a few cases. Here, we identified a Gβ GPB-1 signaling pathway operating in specific serotonergic neurons to the define steady state serotonin (5-HT) synthesis, through a genetic screen for 5-HT synthesis mutants in Caenorhabditis elegans. We found that signaling through cell autonomous GPB-1 to the OCR-2 TRPV channel defines the baseline expression of 5-HT synthesis enzyme tryptophan hydroxylase tph-1 in ADF chemosensory neurons. This Gβ signaling pathway is not essential for establishing the serotonergic cell fates and is mechanistically separated from stress-induced tph-1 upregulation. We identified that ADF-produced 5-HT controls specific innate rhythmic behaviors. These results revealed a Gβ-mediated signaling operating in differentiated cells to specify intrinsic functional properties, and indicate that baseline TPH expression is not a default generic serotonergic fate, but is programmed in a cell-specific manner in the mature nervous system. Cell-specific regulation of TPH expression could be a general principle for tailored steady state 5-HT synthesis in functionally distinct neurons and their regulation of innate behavior. PMID:26402365

  1. State-dependent firing determines intrinsic dendritic Ca2+ signaling in thalamocortical neurons.

    PubMed

    Errington, Adam C; Renger, John J; Uebele, Victor N; Crunelli, Vincenzo

    2010-11-01

    Activity-dependent dendritic Ca(2+) signals play a critical role in multiple forms of nonlinear cellular output and plasticity. In thalamocortical neurons, despite the well established spatial separation of sensory and cortical inputs onto proximal and distal dendrites, respectively, little is known about the spatiotemporal dynamics of intrinsic dendritic Ca(2+) signaling during the different state-dependent firing patterns that are characteristic of these neurons. Here we demonstrate that T-type Ca(2+) channels are expressed throughout the entire dendritic tree of rat thalamocortical neurons and that they mediate regenerative propagation of low threshold spikes, typical of, but not exclusive to, sleep states, resulting in global dendritic Ca(2+) influx. In contrast, actively backpropagating action potentials, typical of wakefulness, result in smaller Ca(2+) influxes that can temporally summate to produce dendritic Ca(2+) accumulations that are linearly related to firing frequency but spatially confined to proximal dendritic regions. Furthermore, dendritic Ca(2+) transients evoked by both action potentials and low-threshold spikes are shaped by Ca(2+) uptake by sarcoplasmic/endoplasmic reticulum Ca(2+) ATPases but do not rely on Ca(2+)-induced Ca(2+) release. Our data demonstrate that thalamocortical neurons are endowed with intrinsic dendritic Ca(2+) signaling properties that are spatially and temporally modified in a behavioral state-dependent manner and suggest that backpropagating action potentials faithfully inform proximal sensory but not distal corticothalamic synapses of neuronal output, whereas corticothalamic synapses only "detect" Ca(2+) signals associated with low-threshold spikes. PMID:21048143

  2. Activation of the Canonical Wnt Signaling Pathway Induces Cementum Regeneration.

    PubMed

    Han, Pingping; Ivanovski, Saso; Crawford, Ross; Xiao, Yin

    2015-07-01

    Canonical Wnt signaling is important in tooth development but it is unclear whether it can induce cementogenesis and promote the regeneration of periodontal tissues lost because of disease. Therefore, the aim of this study is to investigate the influence of canonical Wnt signaling enhancers on human periodontal ligament cell (hPDLCs) cementogenic differentiation in vitro and cementum repair in a rat periodontal defect model. Canonical Wnt signaling was induced by (1) local injection of lithium chloride; (2) local injection of sclerostin antibody; and (3) local injection of a lentiviral construct overexpressing β-catenin. The results showed that the local activation of canonical Wnt signaling resulted in significant new cellular cementum deposition and the formation of well-organized periodontal ligament fibers, which was absent in the control group. In vitro experiments using hPDLCs showed that the Wnt signaling pathway activators significantly increased mineralization, alkaline phosphatase (ALP) activity, and gene and protein expression of the bone and cementum markers osteocalcin (OCN), osteopontin (OPN), cementum protein 1 (CEMP1), and cementum attachment protein (CAP). Our results show that the activation of the canonical Wnt signaling pathway can induce in vivo cementum regeneration and in vitro cementogenic differentiation of hPDLCs. PMID:25556853

  3. Coco is a dual activity modulator of TGFβ signaling

    PubMed Central

    Deglincerti, Alessia; Haremaki, Tomomi; Warmflash, Aryeh; Sorre, Benoit; Brivanlou, Ali H.

    2015-01-01

    The TGFβ signaling pathway is a crucial regulator of developmental processes and disease. The activity of TGFβ ligands is modulated by various families of soluble inhibitors that interfere with the interactions between ligands and receptors. In an unbiased, genome-wide RNAi screen to identify genes involved in ligand-dependent signaling, we unexpectedly identified the BMP/Activin/Nodal inhibitor Coco as an enhancer of TGFβ1 signaling. Coco synergizes with TGFβ1 in both cell culture and Xenopus explants. Molecularly, Coco binds to TGFβ1 and enhances TGFβ1 binding to its receptor Alk5. Thus, Coco acts as both an inhibitor and an enhancer of signaling depending on the ligand it binds. This finding raises the need for a global reconsideration of the molecular mechanisms regulating TGFβ signaling. PMID:26116664

  4. RELIEF OF PROFOUND FEEDBACK INHIBITION OF MITOGENIC SIGNALING BY RAF INHIBITORS ATTENUATES THEIR ACTIVITY IN BRAFV600E MELANOMAS

    PubMed Central

    Lito, Piro; Pratilas, Christine A.; Joseph, Eric W.; Tadi, Madhavi; Halilovic, Ensar; Zubrowski, Matthew; Huang, Alan; Wong, Wai Lin; Callahan, Margaret K.; Merghoub, Taha; Wolchok, Jedd D.; de Stanchina, Elisa; Chandarlapaty, Sarat; Poulikakos, Poulikos I.; Fagin, James A.; Rosen, Neal

    2012-01-01

    SUMMARY BRAFV600E drives tumors by dysregulating ERK signaling. In these tumors, we show that high levels of ERK-dependent negative feedback potently suppress ligand-dependent mitogenic signaling and Ras function. BRAFV600E activation is Ras-independent and it signals as a RAF-inhibitor sensitive monomer. RAF inhibitors potently inhibit RAF monomers and ERK signaling, causing relief of ERK-dependent feedback, reactivation of ligand-dependent signal transduction, increased Ras-GTP and generation of RAF inhibitor-resistant RAF dimers. This results in a rebound in ERK activity and culminates in a new steady state, wherein ERK signaling is elevated compared to its initial nadir after RAF inhibition. In this state, ERK signaling is RAF inhibitor resistant, and MEK inhibitor sensitive, and combined inhibition results in enhancement of ERK-pathway inhibition and antitumor activity. PMID:23153539

  5. Cellular phosphatases facilitate combinatorial processing of receptor-activated signals

    PubMed Central

    Kumar, Dhiraj; Dua, Raina; Srikanth, Ravichandran; Jayaswal, Shilpi; Siddiqui, Zaved; Rao, Kanury VS

    2008-01-01

    Background Although reciprocal regulation of protein phosphorylation represents a key aspect of signal transduction, a larger perspective on how these various interactions integrate to contribute towards signal processing is presently unclear. For example, a key unanswered question is that of how phosphatase-mediated regulation of phosphorylation at the individual nodes of the signaling network translates into modulation of the net signal output and, thereby, the cellular phenotypic response. Results To address the above question we, in the present study, examined the dynamics of signaling from the B cell antigen receptor (BCR) under conditions where individual cellular phosphatases were selectively depleted by siRNA. Results from such experiments revealed a highly enmeshed structure for the signaling network where each signaling node was linked to multiple phosphatases on the one hand, and each phosphatase to several nodes on the other. This resulted in a configuration where individual signaling intermediates could be influenced by a spectrum of regulatory phosphatases, but with the composition of the spectrum differing from one intermediate to another. Consequently, each node differentially experienced perturbations in phosphatase activity, yielding a unique fingerprint of nodal signals characteristic to that perturbation. This heterogeneity in nodal experiences, to a given perturbation, led to combinatorial manipulation of the corresponding signaling axes for the downstream transcription factors. Conclusion Our cumulative results reveal that it is the tight integration of phosphatases into the signaling network that provides the plasticity by which perturbation-specific information can be transmitted in the form of a multivariate output to the downstream transcription factor network. This output in turn specifies a context-defined response, when translated into the resulting gene expression profile. PMID:18798986

  6. Activation of cell signaling via optical manipulation of gold-coated liposomes encapsulating signaling molecules

    NASA Astrophysics Data System (ADS)

    Orsinger, Gabriel V.; Leung, Sarah J.; Romanowski, Marek

    2013-02-01

    Many diseases involve changes in cell signaling cascades, as seen commonly in drug resistant cancers. To better understand these intricate signaling events in diseased cells and tissues, experimental methods of probing cellular communication at a single to multi-cell level are required. We recently introduced a general platform for activation of selected signaling pathways by optically controlled delivery and release of water soluble factors using gold-coated liposomes. In the example presented here, we encapsulated inositol trisphosphate (IP3), a ubiquitous intracellular secondary messenger involved in GPCR and Akt signaling cascades, within 100 nm gold-coated liposomes. The high polarizability of the liposome's unique gold pseudo-shell allows stable optical trapping for subcellular manipulation in the presence of cells. We take this optical manipulation further by optically injecting IP3-containing liposomes into the cytosol of a single cell to initiate localized cell signaling. Upon optical injection of liposomal IP3 into a single ovarian carcinoma cell, we observed localized activation as reported by changes in Indo-1 fluorescence intensity. With established gap junctions between the injected cell and neighboring cells, we monitored propagation of this signaling to and through nearby cells.

  7. Intrinsic excitability state of local neuronal population modulates signal propagation in feed-forward neural networks.

    PubMed

    Han, Ruixue; Wang, Jiang; Yu, Haitao; Deng, Bin; Wei, Xilei; Qin, Yingmei; Wang, Haixu

    2015-04-01

    Reliable signal propagation across distributed brain areas is an essential requirement for cognitive function, and it has been investigated extensively in computational studies where feed-forward network (FFN) is taken as a generic model. But it is still unclear how distinct local network states, which are intrinsically generated by synaptic interactions within each layer, would affect the ability of FFN to transmit information. Here we investigate the impact of such network states on propagating transient synchrony (synfire) and firing rate by a combination of numerical simulations and analytical approach. Specifically, local network dynamics is attributed to the competition between excitatory and inhibitory neurons within each layer. Our results show that concomitant with different local network states, the performance of signal propagation differs dramatically. For both synfire propagation and firing rate propagation, there exists an optimal local excitability state, respectively, that optimizes the performance of signal propagation. Furthermore, we find that long-range connections strongly change the dependence of spiking activity propagation on local network state and propose that these two factors work jointly to determine information transmission across distributed networks. Finally, a simple mean field approach that bridges response properties of long-range connectivity and local subnetworks is utilized to reveal the underlying mechanism. PMID:25933656

  8. Intrinsic excitability state of local neuronal population modulates signal propagation in feed-forward neural networks

    NASA Astrophysics Data System (ADS)

    Han, Ruixue; Wang, Jiang; Yu, Haitao; Deng, Bin; Wei, Xilei; Qin, Yingmei; Wang, Haixu

    2015-04-01

    Reliable signal propagation across distributed brain areas is an essential requirement for cognitive function, and it has been investigated extensively in computational studies where feed-forward network (FFN) is taken as a generic model. But it is still unclear how distinct local network states, which are intrinsically generated by synaptic interactions within each layer, would affect the ability of FFN to transmit information. Here we investigate the impact of such network states on propagating transient synchrony (synfire) and firing rate by a combination of numerical simulations and analytical approach. Specifically, local network dynamics is attributed to the competition between excitatory and inhibitory neurons within each layer. Our results show that concomitant with different local network states, the performance of signal propagation differs dramatically. For both synfire propagation and firing rate propagation, there exists an optimal local excitability state, respectively, that optimizes the performance of signal propagation. Furthermore, we find that long-range connections strongly change the dependence of spiking activity propagation on local network state and propose that these two factors work jointly to determine information transmission across distributed networks. Finally, a simple mean field approach that bridges response properties of long-range connectivity and local subnetworks is utilized to reveal the underlying mechanism.

  9. Global signal regression has complex effects on regional homogeneity of resting state fMRI signal.

    PubMed

    Qing, Zhao; Dong, Zhangye; Li, Sufang; Zang, Yufeng; Liu, Dongqiang

    2015-12-01

    Regional homogeneity (ReHo) quantifies spatially local synchronization of resting state fMRI signal and has been applied to lots of clinic studies. Accumulating evidences demonstrated that the synchronization between spatially distinct brain regions, i.e. functional connectivity, can be remarkably influenced if the global mean time course is regressed out, namely global signal regression (GSR). Very recently, it was reported GSR reduces the test-retest reliability of ReHo, and reduces the positive correlation between ReHo and head motion. In this study, we were interested in two questions: 1) how GSR affects the raw ReHo values and its spatial distribution over the brain; 2) how GSR affects the differences of ReHo between two resting states, eyes open (EO) and eyes closed (EC), in healthy individuals. We found that the ReHo values were reduced by GSR but the spatial distribution of ReHo was not changed remarkably. In addition, split-half reproducibility analysis showed reproducible ReHo difference between EO and EC in some areas (e.g., thalamus and caudate) only with GSR, but showed reproducible ReHo difference in some other area (right temporal pole) only without GSR. The effects of GSR were almost independent of regression of other nuisance covariates. Our results suggest that the influences of GSR on ReHo are remarkable, reliable and complex. For the between-condition comparison, the GSR effects are region specific. We suggest that, for application studies using ReHo approach, it would be helpful to report results both with and without GSR. PMID:26234499

  10. Correlation of nighttime MF signal strength with solar activity

    NASA Astrophysics Data System (ADS)

    Kohata, Hiroki; Kimura, Iwane; Wakai, Noboru; Ogawa, Tadahiko

    Observations of the signal strength of MF broadcasting signals (774/770 kHz) transmitted from Akita, Japan, on board the Japanese Antarctic ice breaker Fuji, bound from Japan to Syowa station, Antarctica, have revealed an interesting positive correlation between strengths of long distance signals propagating at night and solar activity. It is already known that MF propagation characteristics in North America show a negative correlation with solar activity. The present paper, interprets the results by using the multihop method with full-wave analysis. The difference in correlation with solar activity between the results of Fuji and those in North America can be elucidated if it is assumed that there is a ledge in the electron-density profile around an altitude range of 85 to 90 km and that the density of the ledge is smaller in the North American region than in the equatorial region.

  11. Recognition of forearm muscle activity by continuous classification of multi-site mechanomyogram signals.

    PubMed

    Alves, Natasha; Chau, Tom

    2010-01-01

    Recent studies on identifying multiple activation states from mechanomyogram (MMG) signals for the purpose of controlling switching interfaces have employed pattern recognition methods where MMG signal features from multiple muscle sites are extracted and classified. The purpose of this study is to determine if MMG signal features retain enough discriminatory information to allow reliable continuous classification, and to determine if there is a decline in classification accuracy over short time periods. MMG signals were recorded from two accelerometers attached to the flexor carpi radialis and extensor carpi radialis muscles of 12 able-bodied participants as participants performed three classes of forearm muscle activity. The data were collected over five recording sessions, with a ten-minute interval between each session. The data were spliced into 256 ms epochs, and a comprehensive set of signal features was extracted. A pattern classifier, trained with continuously acquired signal features from the first recording session, was tested with signals recorded from the other sessions. The average classification accuracy over the five sessions was 89 ± 2%. There was no obvious declining trend in classification accuracy with time. These results show that MMG signals recorded at the forearm retain enough discriminatory information to allow continuous recognition of hand motion across multiple (>90) repetitions, and the MMG-classifier does not show short-term degradation. These results indicate the potential of MMG as a multifunction control signal for muscle-machine interfaces. PMID:21097038

  12. Receptor tyrosine kinases: mechanisms of activation and signaling

    PubMed Central

    Hubbard, Stevan R.; Miller, W. Todd

    2008-01-01

    Receptor tyrosine kinases (RTKs) are essential components of signal transduction pathways that mediate cell-to-cell communication. These single-pass transmembrane receptors, which bind polypeptide ligands — mainly growth factors — play key roles in processes such as cellular growth, differentiation, metabolism and motility. Recent progress has been achieved towards an understanding of the precise (and varied) mechanisms by which RTKs are activated by ligand binding and by which signals are propagated from the activated receptors to downstream targets in the cell. PMID:17306972

  13. Control of macrophage metabolism and activation by mTOR and Akt signaling

    PubMed Central

    Covarrubias, Anthony J.; Aksoylar, H. Ibrahim; Horng, Tiffany

    2015-01-01

    Macrophages are pleiotropic cells that assume a variety of functions depending on their tissue of residence and tissue state. They maintain homeostasis as well as coordinate responses to stresses such as infection and metabolic challenge. The ability of macrophages to acquire diverse, context-dependent activities requires their activation (or polarization) to distinct functional states. While macrophage activation is well understood at the level of signal transduction and transcriptional regulation, the metabolic underpinnings are poorly understood. Importantly, emerging studies indicate that metabolic shifts play a pivotal role in control of macrophage activation and acquisition of context-dependent effector activities. The signals that drive macrophage activation impinge on metabolic pathways, allowing for coordinate control of macrophage activation and metabolism. Here we discuss how mTOR and Akt, major metabolic regulators and targets of such activation signals, control macrophage metabolism and activation. Dysregulated macrophage activities contribute to many diseases, including infectious, inflammatory, and metabolic diseases and cancer, thus a better understanding of metabolic control of macrophage activation could pave the way to the development of new therapeutic strategies. PMID:26360589

  14. Notch signaling promotes osteoclast maturation and resorptive activity.

    PubMed

    Ashley, Jason W; Ahn, Jaimo; Hankenson, Kurt D

    2015-11-01

    The role of Notch signaling in osteoclast differentiation is controversial with conflicting experimental evidence indicating both stimulatory and inhibitory roles. Differences in experimental protocols and in vivo versus in vitro models may explain the discrepancies between studies. In this study, we investigated cell autonomous roles of Notch signaling in osteoclast differentiation and function by altering Notch signaling during osteoclast differentiation using stimulation with immobilized ligands Jagged1 or Delta-like1 or by suppression with γ-secretase inhibitor DAPT or transcriptional inhibitor SAHM1. Stimulation of Notch signaling in committed osteoclast precursors resulted in larger osteoclasts with a greater number of nuclei and resorptive activity whereas suppression resulted in smaller osteoclasts with fewer nuclei and suppressed resorptive activity. Conversely, stimulation of Notch signaling in osteoclast precursors prior to induction of osteoclastogenesis resulted in fewer osteoclasts. Our data support a mechanism of context-specific Notch signaling effects wherein Notch stimulation inhibits commitment to osteoclast differentiation, but enhances the maturation and function of committed precursors. PMID:25914241

  15. Wnt signaling and the activation of myogenesis in mammals.

    PubMed

    Cossu, G; Borello, U

    1999-12-15

    In the amniote embryos, specification of skeletal myoblasts occurs in the paraxial mesoderm in response to a number of signaling molecules produced by neighboring tissues such as neural tube, notochord and dorsal ectoderm. Candidate molecules for this complex signaling activity include Sonic hedgehog, Wnts and Noggin as positive activators and BMP4 as a possible inhibitor. Recently, the receptors and the post-receptor pathways for Sonic hedgehog and Wnts have been characterized, and this has opened up the possibility of linking these signaling events to the activation of myogenic regulatory factor genes such as Myf5 and MyoD and functionally related genes such as Pax3. Here we focus on the role of Wnts, their putative receptors Frizzled and the soluble antagonist Frzb1 in regulating mammalian myogenesis. Although it is becoming evident that the signaling downstream of Frizzled receptors is much more complex than anticipated, it is conceivable that it may lead to transcriptional activation of Myf5 and MyoD and to initiation of myogenesis. However, the fact that both Wnts and Sonic hedgehog have a strong effect on cell proliferation and survival suggests that they may contribute to the overall process of myogenesis by a combination of these different biological activities. PMID:10601008

  16. Wnt signaling and the activation of myogenesis in mammals.

    PubMed Central

    Cossu, G; Borello, U

    1999-01-01

    In the amniote embryos, specification of skeletal myoblasts occurs in the paraxial mesoderm in response to a number of signaling molecules produced by neighboring tissues such as neural tube, notochord and dorsal ectoderm. Candidate molecules for this complex signaling activity include Sonic hedgehog, Wnts and Noggin as positive activators and BMP4 as a possible inhibitor. Recently, the receptors and the post-receptor pathways for Sonic hedgehog and Wnts have been characterized, and this has opened up the possibility of linking these signaling events to the activation of myogenic regulatory factor genes such as Myf5 and MyoD and functionally related genes such as Pax3. Here we focus on the role of Wnts, their putative receptors Frizzled and the soluble antagonist Frzb1 in regulating mammalian myogenesis. Although it is becoming evident that the signaling downstream of Frizzled receptors is much more complex than anticipated, it is conceivable that it may lead to transcriptional activation of Myf5 and MyoD and to initiation of myogenesis. However, the fact that both Wnts and Sonic hedgehog have a strong effect on cell proliferation and survival suggests that they may contribute to the overall process of myogenesis by a combination of these different biological activities. PMID:10601008

  17. The HAMP Signal Relay Domain Adopts Multiple Conformational States through Collective Piston and Tilt Motions

    PubMed Central

    Zhu, Lizhe; Bolhuis, Peter G.; Vreede, Jocelyne

    2013-01-01

    The HAMP domain is a linker region in prokaryotic sensor proteins and relays input signals to the transmitter domain and vice versa. Functional as a dimer, the structure of HAMP shows a parallel coiled-coil motif comprising four helices. To date, it is unclear how HAMP can relay signals from one domain to another, although several models exist. In this work, we use molecular simulation to test the hypothesis that HAMP adopts different conformations, one of which represents an active, signal-relaying configuration, and another an inactive, resting state. We first performed molecular dynamics simulation on the prototype HAMP domain Af1503 from Archaeoglobus fulgidus. We explored its conformational space by taking the structure of the A291F mutant disabling HAMP activity as a starting point. These simulations revealed additional conformational states that differ in the tilt angles between the helices as well as the relative piston shifts of the helices relative to each other. By enhancing the sampling in a metadynamics set up, we investigated three mechanistic models for HAMP signal transduction. Our results indicate that HAMP can access additional conformational states characterized by piston motion. Furthermore, the piston motion of the N-terminal helix of one monomer is directly correlated with the opposite piston motion of the C-terminal helix of the other monomer. The change in piston motion is accompanied by a change in tilt angle between the monomers, thus revealing that HAMP exhibits a collective motion, i.e. a combination of changes in tilt angles and a piston-like displacement. Our results provide insights into the conformational changes that underlie the signaling mechanism involving HAMP. PMID:23468603

  18. Signaling pathways activated by a protease allergen in basophils

    PubMed Central

    Rosenstein, Rachel K.; Bezbradica, Jelena S.; Yu, Shuang; Medzhitov, Ruslan

    2014-01-01

    Allergic diseases represent a significant burden in industrialized countries, but why and how the immune system responds to allergens remain largely unknown. Because many clinically significant allergens have proteolytic activity, and many helminths express proteases that are necessary for their life cycles, host mechanisms likely have evolved to detect the proteolytic activity of helminth proteases, which may be incidentally activated by protease allergens. A cysteine protease, papain, is a prototypic protease allergen that can directly activate basophils and mast cells, leading to the production of cytokines, including IL-4, characteristic of the type 2 immune response. The mechanism of papain’s immunogenic activity remains unknown. Here we have characterized the cellular response activated by papain in basophils. We find that papain-induced IL-4 production requires calcium flux and activation of PI3K and nuclear factor of activated T cells. Interestingly, papain-induced IL-4 production was dependent on the immunoreceptor tyrosine-based activation motif (ITAM) adaptor protein Fc receptor γ-chain, even though the canonical ITAM signaling was not activated by papain. Collectively, these data characterize the downstream signaling pathway activated by a protease allergen in basophils. PMID:25369937

  19. Response and fluctuations of a two-state signaling module with feedback

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, Manoj; Borowski, Peter; Jülicher, Frank; Zapotocky, Martin

    2007-08-01

    We study the stochastic kinetics of a signaling module consisting of a two-state stochastic point process with negative feedback. In the active state, a product is synthesized which increases the active-to-inactive transition rate of the process. We analyze this simple autoregulatory module using a path-integral technique based on the temporal statistics of state flips of the process. We develop a systematic framework to calculate averages, autocorrelations, and response functions by treating the feedback as a weak perturbation. Explicit analytical results are obtained to first order in the feedback strength. Monte Carlo simulations are performed to test the analytical results in the weak feedback limit and to investigate the strong feedback regime. We conclude by relating some of our results to experimental observations in the olfactory and visual sensory systems.

  20. A Temporal Window for Signal Activation Dictates the Dimensions of a Nodal Signaling Domain

    PubMed Central

    van Boxtel, Antonius L.; Chesebro, John E.; Heliot, Claire; Ramel, Marie-Christine; Stone, Richard K.; Hill, Caroline S.

    2015-01-01

    Summary Morphogen signaling is critical for the growth and patterning of tissues in embryos and adults, but how morphogen signaling gradients are generated in tissues remains controversial. The morphogen Nodal was proposed to form a long-range signaling gradient via a reaction-diffusion system, on the basis of differential diffusion rates of Nodal and its antagonist Lefty. Here we use a specific zebrafish Nodal biosensor combined with immunofluorescence for phosphorylated Smad2 to demonstrate that endogenous Nodal is unlikely to diffuse over a long range. Instead, short-range Nodal signaling activation in a temporal window is sufficient to determine the dimensions of the Nodal signaling domain. The size of this temporal window is set by the differentially timed production of Nodal and Lefty, which arises mainly from repression of Lefty translation by the microRNA miR-430. Thus, temporal information is transformed into spatial information to define the dimensions of the Nodal signaling domain and, consequently, to specify mesendoderm. PMID:26506307

  1. A Temporal Window for Signal Activation Dictates the Dimensions of a Nodal Signaling Domain.

    PubMed

    van Boxtel, Antonius L; Chesebro, John E; Heliot, Claire; Ramel, Marie-Christine; Stone, Richard K; Hill, Caroline S

    2015-10-26

    Morphogen signaling is critical for the growth and patterning of tissues in embryos and adults, but how morphogen signaling gradients are generated in tissues remains controversial. The morphogen Nodal was proposed to form a long-range signaling gradient via a reaction-diffusion system, on the basis of differential diffusion rates of Nodal and its antagonist Lefty. Here we use a specific zebrafish Nodal biosensor combined with immunofluorescence for phosphorylated Smad2 to demonstrate that endogenous Nodal is unlikely to diffuse over a long range. Instead, short-range Nodal signaling activation in a temporal window is sufficient to determine the dimensions of the Nodal signaling domain. The size of this temporal window is set by the differentially timed production of Nodal and Lefty, which arises mainly from repression of Lefty translation by the microRNA miR-430. Thus, temporal information is transformed into spatial information to define the dimensions of the Nodal signaling domain and, consequently, to specify mesendoderm. PMID:26506307

  2. State Court Law-Related Education Activities.

    ERIC Educational Resources Information Center

    American Bar Association, Chicago, IL. Special Committee on Youth Education for Citizenship.

    This document lists the law-related education activities conducted by state courts. The listings are arranged by state. Entries list the name of the court, a list of activities provided, descriptions of unusual programs, guidelines for programs that some of the courts have developed, and the name, title or committee, address, and phone number of a…

  3. Metabolic signals and innate immune activation in obesity and exercise.

    PubMed

    Ringseis, Robert; Eder, Klaus; Mooren, Frank C; Krüger, Karsten

    2015-01-01

    The combination of a sedentary lifestyle and excess energy intake has led to an increased prevalence of obesity which constitutes a major risk factor for several co-morbidities including type 2 diabetes and cardiovascular diseases. Intensive research during the last two decades has revealed that a characteristic feature of obesity linking it to insulin resistance is the presence of chronic low-grade inflammation being indicative of activation of the innate immune system. Recent evidence suggests that activation of the innate immune system in the course of obesity is mediated by metabolic signals, such as free fatty acids (FFAs), being elevated in many obese subjects, through activation of pattern recognition receptors thereby leading to stimulation of critical inflammatory signaling cascades, like IκBα kinase/nuclear factor-κB (IKK/NF- κB), endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) and NOD-like receptor P3 (NLRP3) inflammasome pathway, that interfere with insulin signaling. Exercise is one of the main prescribed interventions in obesity management improving insulin sensitivity and reducing obesity- induced chronic inflammation. This review summarizes current knowledge of the cellular recognition mechanisms for FFAs, the inflammatory signaling pathways triggered by excess FFAs in obesity and the counteractive effects of both acute and chronic exercise on obesity-induced activation of inflammatory signaling pathways. A deeper understanding of the effects of exercise on inflammatory signaling pathways in obesity is useful to optimize preventive and therapeutic strategies to combat the increasing incidence of obesity and its comorbidities. PMID:25825956

  4. Activation of signalling by the activin receptor complex.

    PubMed Central

    Attisano, L; Wrana, J L; Montalvo, E; Massagué, J

    1996-01-01

    Activin exerts its effects by simultaneously binding to two types of p rotein serine/threonine kinase receptors, each type existing in various isoforms. Using the ActR-IB and ActR-IIB receptor isoforms, we have investigated the mechanism of activin receptor activation. ActR-IIB are phosphoproteins with demonstrable affinity for each other. However, activin addition strongly promotes an interaction between these two proteins. Activin binds directly to ActR-IIB, and this complex associates with ActR-IB, which does not bind ligand on its own. In the resulting complex, ActR-IB becomes hyperphosphorylated, and this requires the kinase activity of ActR-IIB. Mutation of conserved serines and threonines in the GS domain, a region just upstream of the kinase domain in ActR-IB, abrogates both phosphorylation and signal propagation, suggesting that this domain contains phosphorylation sites required for signalling. ActR-IB activation can be mimicked by mutation of Thr-206 to aspartic acid, which yields a construct, ActR-IB(T206D), that signals in the absence of ligand. Furthermore, the signalling activity of this mutant construct is undisturbed by overexpression of a dominant negative kinase-defective ActR-IIB construct, indicating that ActR-IB(T206D) can signal independently of ActR-IIB. The evidence suggests that ActR-IIB acts as a primary activin receptor and ActR-IB acts as a downstream transducer of activin signals. PMID:8622651

  5. Imaging the coordination of multiple signaling activities in living cells

    PubMed Central

    Welch, Christopher M.; Elliott, Hunter; Danuser, Gaudenz; Hahn, Klaus M.

    2013-01-01

    Preface Cellular signal transduction occurs in complex and redundant interaction networks that are best examined at the level of single cells by simultaneously monitoring the activation dynamics of multiple components. Recent advances in biosensor technology have made it possible to visualize and quantify the activation of multiple network nodes in the same living cell. The precision and scope of this approach has been greatly extended by novel computational approaches to determine the relationships between different networks, studied in separate cells. PMID:22016058

  6. Crosstalk and Signaling Switches in Mitogen-Activated Protein Kinase Cascades

    PubMed Central

    Fey, Dirk; Croucher, David R.; Kolch, Walter; Kholodenko, Boris N.

    2012-01-01

    Mitogen-activated protein kinase (MAPK) cascades control cell fate decisions, such as proliferation, differentiation, and apoptosis by integrating and processing intra- and extracellular cues. However, similar MAPK kinetic profiles can be associated with opposing cellular decisions depending on cell type, signal strength, and dynamics. This implies that signaling by each individual MAPK cascade has to be considered in the context of the entire MAPK network. Here, we develop a dynamic model of feedback and crosstalk for the three major MAPK cascades; extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (p38), c-Jun N-terminal kinase (JNK), and also include input from protein kinase B (AKT) signaling. Focusing on the bistable activation characteristics of the JNK pathway, this model explains how pathway crosstalk harmonizes different MAPK responses resulting in pivotal cell fate decisions. We show that JNK can switch from a transient to sustained activity due to multiple positive feedback loops. Once activated, positive feedback locks JNK in a highly active state and promotes cell death. The switch is modulated by the ERK, p38, and AKT pathways. ERK activation enhances the dual specificity phosphatase (DUSP) mediated dephosphorylation of JNK and shifts the threshold of the apoptotic switch to higher inputs. Activation of p38 restores the threshold by inhibiting ERK activity via the PP1 or PP2A phosphatases. Finally, AKT activation inhibits the JNK positive feedback, thus abrogating the apoptotic switch and allowing only proliferative signaling. Our model facilitates understanding of how cancerous deregulations disturb MAPK signal processing and provides explanations for certain drug resistances. We highlight a critical role of DUSP1 and DUSP2 expression patterns in facilitating the switching of JNK activity and show how oncogene induced ERK hyperactivity prevents the normal apoptotic switch explaining the failure of certain drugs to

  7. MECHANISTIC PATHWAYS AND BIOLOGICAL ROLES FOR RECEPTOR-INDEPENDENT ACTIVATORS OF G-PROTEIN SIGNALING

    PubMed Central

    Blumer, Joe B.; Smrcka, Alan V.; Lanier, S.M.

    2007-01-01

    Signal processing via heterotrimeric G-proteins in response to cell surface receptors is a central and much investigated aspect of how cells integrate cellular stimuli to produce coordinated biological responses. The system is a target of numerous therapeutic agents, plays an important role in adaptive processes of organs, and aberrant processing of signals through these transducing systems is a component of various disease states. In addition to GPCR-mediated activation of G-protein signaling, nature has evolved creative ways to manipulate and utilize the Gαβγ heterotrimer or Gα and Gαβγ subunits independent of the cell surface receptor stimuli. In such situations, the G-protein subunits (Gα and Gαβγ) may actually be complexed with alternative binding partners independent of the typical heterotrimeric Gαβγ. Such regulatory accessory proteins include the family of RGS proteins that accelerate the GTPase activity of Gα and various entities that influence nucleotide binding properties and/or subunit interaction. The latter group of proteins includes receptor independent activators of G-protein signaling or AGS proteins that play surprising roles in signal processing. This review provides an overview of our current knowledge regarding AGS proteins. AGS proteins are indicative of a growing number of accessory proteins that influence signal propagation, facilitate cross talk between various types of signaling pathways and provide a platform for diverse functions of both the heterotrimeric Gαβγ and the individual Gα and Gαβγ subunits. PMID:17240454

  8. Protein kinase A activity and Hedgehog signaling pathway.

    PubMed

    Kotani, Tomoya

    2012-01-01

    Protein kinase A (PKA) is a well-known kinase that plays fundamental roles in a variety of biological processes. In Hedgehog-responsive cells, PKA plays key roles in proliferation and fate specification by modulating the transduction of Hedgehog signaling. In the absence of Hedgehog, a basal level of PKA activity represses the transcription of Hedgehog target genes. The main substrates of PKA in this process are the Ci/Gli family of bipotential transcription factors, which activate and repress Hedgehog target gene expression. PKA phosphorylates Ci/Gli, promoting the production of the repressor forms of Ci/Gli and thus repressing Hedgehog target gene expression. In contrast, the activation of Hedgehog signaling in response to Hedgehog increases the active forms of Ci/Gli, resulting in Hedgehog target gene expression. Because both decreased and increased levels of PKA activity cause abnormal cell proliferation and alter cell fate specification, the basal level of PKA activity in Hedgehog-responsive cells should be precisely regulated. However, the mechanism by which PKA activity is regulated remains obscure and appears to vary between cell types, tissues, and organisms. To date, two mechanisms have been proposed. One is a classical mechanism in which PKA activity is regulated by a small second messenger, cAMP; the other is a novel mechanism in which PKA activity is regulated by a protein, Misty somites. PMID:22391308

  9. Activation of B cells by non-canonical helper signals

    PubMed Central

    Cerutti, Andrea; Cols, Montserrat; Puga, Irene

    2012-01-01

    Cognate interaction between T and B lymphocytes of the adaptive immune system is essential for the production of high-affinity antibodies against microbes, and for the establishment of long-term immunological memory. Growing evidence shows that—in addition to presenting antigens to T and B cells—macrophages, dendritic cells and other cells of the innate immune system provide activating signals to B cells, as well as survival signals to antibody-secreting plasma cells. Here, we discuss how these innate immune cells contribute to the induction of highly diversified and temporally sustained antibody responses, both systemically and at mucosal sites of antigen entry. PMID:22868664

  10. Molecular hydrogen suppresses activated Wnt/β-catenin signaling.

    PubMed

    Lin, Yingni; Ohkawara, Bisei; Ito, Mikako; Misawa, Nobuaki; Miyamoto, Kentaro; Takegami, Yasuhiko; Masuda, Akio; Toyokuni, Shinya; Ohno, Kinji

    2016-01-01

    Molecular hydrogen (H2) is effective for many diseases. However, molecular bases of H2 have not been fully elucidated. Cumulative evidence indicates that H2 acts as a gaseous signal modulator. We found that H2 suppresses activated Wnt/β-catenin signaling by promoting phosphorylation and degradation οf β-catenin. Either complete inhibition of GSK3 or mutations at CK1- and GSK3-phosphorylation sites of β-catenin abolished the suppressive effect of H2. H2 did not increase GSK3-mediated phosphorylation of glycogen synthase, indicating that H2 has no direct effect on GSK3 itself. Knock-down of adenomatous polyposis coli (APC) or Axin1, which form the β-catenin degradation complex, minimized the suppressive effect of H2 on β-catenin accumulation. Accordingly, the effect of H2 requires CK1/GSK3-phosphorylation sites of β-catenin, as well as the β-catenin degradation complex comprised of CK1, GSK3, APC, and Axin1. We additionally found that H2 reduces the activation of Wnt/β-catenin signaling in human osteoarthritis chondrocytes. Oral intake of H2 water tended to ameliorate cartilage degradation in a surgery-induced rat osteoarthritis model through attenuating β-catenin accumulation. We first demonstrate that H2 suppresses abnormally activated Wnt/β-catenin signaling, which accounts for the protective roles of H2 in a fraction of diseases. PMID:27558955

  11. Spatial Regulation and the Rate of Signal Transduction Activation

    PubMed Central

    Batada, Nizar N; Shepp, Larry A; Siegmund, David O; Levitt, Michael

    2006-01-01

    Of the many important signaling events that take place on the surface of a mammalian cell, activation of signal transduction pathways via interactions of cell surface receptors is one of the most important. Evidence suggests that cell surface proteins are not as freely diffusible as implied by the classic fluid mosaic model and that their confinement to membrane domains is regulated. It is unknown whether these dynamic localization mechanisms function to enhance signal transduction activation rate or to minimize cross talk among pathways that share common intermediates. To determine which of these two possibilities is more likely, we derive an explicit equation for the rate at which cell surface membrane proteins interact based on a Brownian motion model in the presence of endocytosis and exocytosis. We find that in the absence of any diffusion constraints, cell surface protein interaction rate is extremely high relative to cytoplasmic protein interaction rate even in a large mammalian cell with a receptor abundance of a mere two hundred molecules. Since a larger number of downstream signaling events needs to take place, each occurring at a much slower rate than the initial activation via association of cell surface proteins, we conclude that the role of co-localization is most likely that of cross-talk reduction rather than coupling efficiency enhancement. PMID:16699596

  12. Molecular hydrogen suppresses activated Wnt/β-catenin signaling

    PubMed Central

    Lin, Yingni; Ohkawara, Bisei; Ito, Mikako; Misawa, Nobuaki; Miyamoto, Kentaro; Takegami, Yasuhiko; Masuda, Akio; Toyokuni, Shinya; Ohno, Kinji

    2016-01-01

    Molecular hydrogen (H2) is effective for many diseases. However, molecular bases of H2 have not been fully elucidated. Cumulative evidence indicates that H2 acts as a gaseous signal modulator. We found that H2 suppresses activated Wnt/β-catenin signaling by promoting phosphorylation and degradation οf β-catenin. Either complete inhibition of GSK3 or mutations at CK1- and GSK3-phosphorylation sites of β-catenin abolished the suppressive effect of H2. H2 did not increase GSK3-mediated phosphorylation of glycogen synthase, indicating that H2 has no direct effect on GSK3 itself. Knock-down of adenomatous polyposis coli (APC) or Axin1, which form the β-catenin degradation complex, minimized the suppressive effect of H2 on β-catenin accumulation. Accordingly, the effect of H2 requires CK1/GSK3-phosphorylation sites of β-catenin, as well as the β-catenin degradation complex comprised of CK1, GSK3, APC, and Axin1. We additionally found that H2 reduces the activation of Wnt/β-catenin signaling in human osteoarthritis chondrocytes. Oral intake of H2 water tended to ameliorate cartilage degradation in a surgery-induced rat osteoarthritis model through attenuating β-catenin accumulation. We first demonstrate that H2 suppresses abnormally activated Wnt/β-catenin signaling, which accounts for the protective roles of H2 in a fraction of diseases. PMID:27558955

  13. BMP2 Transfer to Neighboring Cells and Activation of Signaling.

    PubMed

    Alborzinia, Hamed; Shaikhkarami, Marjan; Hortschansky, Peter; Wölfl, Stefan

    2016-09-01

    Morphogen gradients and concentration are critical features during early embryonic development and cellular differentiation. Previously we reported the preparation of biologically active, fluorescently labeled BMP2 and quantitatively analyzed their binding to the cell surface and followed BMP2 endocytosis over time on the level of single endosomes. Here we show that this internalized BMP2 can be transferred to neighboring cells and, moreover, also activates downstream BMP signaling in adjacent cells, indicated by Smad1/5/8 phosphorylation and activation of the downstream target gene id1. Using a 3D matrix to modulate cell-cell contacts in culture we could show that direct cell-cell contact significantly increased BMP2 transfer. Using inhibitors of vesicular transport, transfer was strongly inhibited. Interestingly, cotreatment with the physiological BMP inhibitor Noggin increased BMP2 uptake and transfer, albeit activation of Smad signaling in neighboring cells was completely suppressed. Our findings present a novel and interesting mechanism by which morphogens such as BMP2 can be transferred between cells and how this is modulated by BMP antagonists such as Noggin, and how this influences activation of Smad signaling by BMP2 in neighboring cells. PMID:27306974

  14. G Protein Activation Stimulates Phospholipase D Signaling in Plants.

    PubMed Central

    Munnik, T.; Arisz, S. A.; De Vrije, T.; Musgrave, A.

    1995-01-01

    We provide direct evidence for phospholipase D (PLD) signaling in plants by showing that this enzyme is stimulated by the G protein activators mastoparan, ethanol, and cholera toxin. An in vivo assay for PLD activity in plant cells was developed based on the use of a "reporter alcohol" rather than water as a transphosphatidylation substrate. The product was a phosphatidyl alcohol, which, in contrast to the normal product phosphatidic acid, is a specific measure of PLD activity. When 32P-labeled cells were treated with 0.1% n-butanol, 32P-phosphatidyl butanol (32P-PtdBut) was formed in a time-dependent manner. In cells treated with any of the three G protein activators, the production of 32P-PtdBut was increased in a dose-dependent manner. The G protein involved was pertussis toxin insensitive. Ethanol could activate PLD but was itself consumed by PLD as transphosphatidylation substrate. In contrast, secondary alcohols (e.g., sec-butyl alcohol) activated PLD but did not function as substrate, whereas tertiary alcohols did neither. Although most of the experiments were performed with the green alga Chlamydomonas eugametos, the relevance for higher plants was demonstrated by showing that PLD in carnation petals could also be activated by mastoparan. The results indicate that PLD activation must be considered as a potential signal transduction mechanism in plants, just as in animals. PMID:12242371

  15. Purmorphamine induces osteogenesis by activation of the hedgehog signaling pathway.

    PubMed

    Wu, Xu; Walker, John; Zhang, Jie; Ding, Sheng; Schultz, Peter G

    2004-09-01

    Previously, a small molecule, purmorphamine, was identified that selectively induces osteogenesis in multipotent mesenchymal progenitor cells. In order to gain insights into the mechanism of action of purmorphamine, high-density oligonucleotide microarrays were used to profile gene expression in multipotent mesenchymal progenitor cells treated with either purmorphamine or bone morphogenetic protein-4 (BMP-4). In contrast to BMP-4 treatment, purmorphamine activates the Hedgehog (Hh) signaling pathway, resulting in the up- and downregulation of its downstream target genes, including Gli1 and Patched. Moreover, the known Hh signaling antagonists, cyclopamine and forskolin, completely block the osteogenesis and Glimediated transcription induced by purmorphamine. These results demonstrate that purmorphamine is a small molecule agonist of Hedgehog signaling, and it may ultimately be useful in the treatment of bone-related disease and neurodegenerative disease. PMID:15380183

  16. Chemical activation of a food deprivation signal extends lifespan.

    PubMed

    Lucanic, Mark; Garrett, Theo; Yu, Ivan; Calahorro, Fernando; Asadi Shahmirzadi, Azar; Miller, Aaron; Gill, Matthew S; Hughes, Robert E; Holden-Dye, Lindy; Lithgow, Gordon J

    2016-10-01

    Model organisms subject to dietary restriction (DR) generally live longer. Accompanying this lifespan extension are improvements in overall health, based on multiple metrics. This indicates that pharmacological treatments that mimic the effects of DR could improve health in humans. To find new chemical structures that extend lifespan, we screened 30 000 synthetic, diverse drug-like chemicals in Caenorhabditis elegans and identified several structurally related compounds that acted through DR mechanisms. The most potent of these NP1 impinges upon a food perception pathway by promoting glutamate signaling in the pharynx. This results in the overriding of a GPCR pathway involved in the perception of food and which normally acts to decrease glutamate signals. Our results describe the activation of a dietary restriction response through the pharmacological masking of a novel sensory pathway that signals the presence of food. This suggests that primary sensory pathways may represent novel targets for human pharmacology. PMID:27220516

  17. Quantum detection of coherent-state signals in the presence of noise

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V. A.; Lau, C. W.

    2003-01-01

    A general method for solving an important class of quantum detection problems will be presented and evaluated. The quantum theory for detecting pure states for communications purposes has been developed over two decades ago, however the mixed state problem representing signal plus noise states has received little attention due to its great complexity. Here we develop a practical model for solving the mixed-state problem using a discrete approximation to the coherent-state representation of signal plus noise density operators.

  18. Small molecule activation of NOTCH signaling inhibits acute myeloid leukemia

    PubMed Central

    Ye, Qi; Jiang, Jue; Zhan, Guanqun; Yan, Wanyao; Huang, Liang; Hu, Yufeng; Su, Hexiu; Tong, Qingyi; Yue, Ming; Li, Hua; Yao, Guangmin; Zhang, Yonghui; Liu, Hudan

    2016-01-01

    Aberrant activation of the NOTCH signaling pathway is crucial for the onset and progression of T cell leukemia. Yet recent studies also suggest a tumor suppressive role of NOTCH signaling in acute myeloid leukemia (AML) and reactivation of this pathway offers an attractive opportunity for anti-AML therapies. N-methylhemeanthidine chloride (NMHC) is a novel Amaryllidaceae alkaloid that we previously isolated from Zephyranthes candida, exhibiting inhibitory activities in a variety of cancer cells, particularly those from AML. Here, we report NMHC not only selectively inhibits AML cell proliferation in vitro but also hampers tumor development in a human AML xenograft model. Genome-wide gene expression profiling reveals that NMHC activates the NOTCH signaling. Combination of NMHC and recombinant human NOTCH ligand DLL4 achieves a remarkable synergistic effect on NOTCH activation. Moreover, pre-inhibition of NOTCH by overexpression of dominant negative MAML alleviates NMHC-mediated cytotoxicity in AML. Further mechanistic analysis using structure-based molecular modeling as well as biochemical assays demonstrates that NMHC docks in the hydrophobic cavity within the NOTCH1 negative regulatory region (NRR), thus promoting NOTCH1 proteolytic cleavage. Our findings thus establish NMHC as a potential NOTCH agonist that holds great promises for future development as a novel agent beneficial to patients with AML. PMID:27211848

  19. Activation of a signaling cascade by cytoskeleton stretch.

    PubMed

    Tamada, Masako; Sheetz, Michael P; Sawada, Yasuhiro

    2004-11-01

    Cells sense and respond to mechanical force. However, the mechanisms of transduction of extracellular matrix (ECM) forces to biochemical signals are not known. After removing the cell membrane and soluble proteins by Triton X-100 extraction, we found that the remaining complex (Triton cytoskeletons) activated Rap1 upon stretch. Rap1 guanine nucleotide exchange factor, C3G, was required for this activation; C3G as well as the adaptor protein, CrkII, in cell extract bound to Triton cytoskeletons in a stretch-dependent manner. CrkII binding, which was Cas dependent, correlated with stretch-dependent tyrosine phosphorylation of proteins in Triton cytoskeletons including Cas at the contacts with ECM. These in vitro findings were compatible with in vivo observations of stretch-enhanced phosphotyrosine signals, accumulation of CrkII at cell-ECM contacts, and CrkII-Cas colocalization. We suggest that mechanical force on Triton cytoskeletons activates local tyrosine phosphorylation, which provides docking sites for cytosolic proteins, and initiates signaling to activate Rap1. PMID:15525532

  20. Small molecule activation of NOTCH signaling inhibits acute myeloid leukemia.

    PubMed

    Ye, Qi; Jiang, Jue; Zhan, Guanqun; Yan, Wanyao; Huang, Liang; Hu, Yufeng; Su, Hexiu; Tong, Qingyi; Yue, Ming; Li, Hua; Yao, Guangmin; Zhang, Yonghui; Liu, Hudan

    2016-01-01

    Aberrant activation of the NOTCH signaling pathway is crucial for the onset and progression of T cell leukemia. Yet recent studies also suggest a tumor suppressive role of NOTCH signaling in acute myeloid leukemia (AML) and reactivation of this pathway offers an attractive opportunity for anti-AML therapies. N-methylhemeanthidine chloride (NMHC) is a novel Amaryllidaceae alkaloid that we previously isolated from Zephyranthes candida, exhibiting inhibitory activities in a variety of cancer cells, particularly those from AML. Here, we report NMHC not only selectively inhibits AML cell proliferation in vitro but also hampers tumor development in a human AML xenograft model. Genome-wide gene expression profiling reveals that NMHC activates the NOTCH signaling. Combination of NMHC and recombinant human NOTCH ligand DLL4 achieves a remarkable synergistic effect on NOTCH activation. Moreover, pre-inhibition of NOTCH by overexpression of dominant negative MAML alleviates NMHC-mediated cytotoxicity in AML. Further mechanistic analysis using structure-based molecular modeling as well as biochemical assays demonstrates that NMHC docks in the hydrophobic cavity within the NOTCH1 negative regulatory region (NRR), thus promoting NOTCH1 proteolytic cleavage. Our findings thus establish NMHC as a potential NOTCH agonist that holds great promises for future development as a novel agent beneficial to patients with AML. PMID:27211848

  1. Androgen activates β-catenin signaling in bladder cancer cells.

    PubMed

    Li, Yi; Zheng, Yichun; Izumi, Koji; Ishiguro, Hitoshi; Ye, Bo; Li, Faqian; Miyamoto, Hiroshi

    2013-06-01

    Androgen receptor (AR) signals have been implicated in bladder carcinogenesis and tumor progression. Activation of Wnt/β-catenin signaling has also been reported to correlate with bladder cancer progression and poor patients' outcomes. However, cross talk between AR and β-catenin pathways in bladder cancer remains uncharacterized. In radical cystectomy specimens, we immunohistochemically confirmed aberrant expression of β-catenin especially in aggressive tumors. There was a strong association between nuclear expressions of AR and β-catenin in bladder tumors (P=0.0215). Kaplan-Meier and log-rank tests further revealed that reduced membranous β-catenin expression (P=0.0276), nuclear β-catenin expression (P=0.0802), and co-expression of nuclear AR and β-catenin (P=0.0043) correlated with tumor progression after cystectomy. We then assessed the effects of androgen on β-catenin in AR-positive and AR-negative bladder cancer cell lines. A synthetic androgen R1881 increased the expression of an active form of β-catenin and its downstream target c-myc only in AR-positive lines. R1881 also enhanced the activity of β-catenin-mediated transcription, which was abolished by an AR antagonist hydroxyflutamide. Using western blotting and immunofluorescence, R1881 was found to induce nuclear translocation of β-catenin when co-localized with AR. Finally, co-immunoprecipitation revealed androgen-induced associations of AR with β-catenin or T-cell factor (TCF) in bladder cancer cells. Thus, it was likely that androgen was able to activate β-catenin signaling through the AR pathway in bladder cancer cells. Our results also suggest that activation of β-catenin signaling possibly via formation of AR/β-catenin/TCF complex contributes to the progression of bladder cancer, which may enhance the feasibility of androgen deprivation as a potential therapeutic approach. PMID:23447569

  2. Analysis of signal degradation in an integrated active crossbar switch

    NASA Astrophysics Data System (ADS)

    Probst, David K.; Sodergren, Clifford C.; Krainak, Michael A.

    1996-01-01

    One of the most desirable features for a modern systems architecture is reconfigurability. It facilitates the sharing of various processing and memory resources among many different subsystems, thereby reducing the need for each subsystem to duplicate these resources. Reducing duplication also reduces size, weight, power consumption, and cost; all important considerations, especially in modern military systems. Sensor data requires very-wide- bandwidth, point-to-point connections, which are easily provided by fiber optics with good noise immunity, but the switching of such wide-bandwidth signals is problematic because electrical switches have both limited bandwidth and limited switching times. A wide- bandwidth, reconfigurable optical switch is required that overcomes coupling and splitting losses experienced by the optical signal passing through the switch so that sufficient signal- fidelity is maintained. In this paper, we investigate an integrated, active (i.e. amplifying) photonic crossbar switch to determine the signal degradation incurred for intensity modulation and direct detection using an NRZ data format and an ideal, matched-filter receiver. Various device configurations are analyzed in order to determine which produces the smallest degradation of the signal-to-noise ratio.

  3. Correlation of hemodynamic and fluorescence signals under resting state conditions in mice's barrel field cortex.

    PubMed

    Bélanger, Samuel; de Souza, Bruno Oliveira Ferreira; Casanova, Christian; Lesage, Frédéric

    2016-03-11

    Both neurons and astrocytes are known to affect local vascular response in the brain following neuronal activity. In order to differentiate the contributions of each cell type to the hemodynamic response during stimulation and resting state, intrinsic optical signal (IOI) was recorded synchronized with fluorescence imaging of calcium concentration sensitive dye Oregon Green BAPTA-1 AM. By changing the stimulation parameters (frequency and duration), it was possible to individually promote neuronal and glial responses and to compare them to levels of oxy (HbO), deoxy (HbR) and total (HbT) hemoglobin concentrations. Finally, resting state recordings were done to investigate the possible correlation between hemoglobin fluctuation and calcium transients, based on different frequency bands associated either with neuronal or glial activity. PMID:26850574

  4. Cooperativity between MAPK and PI3K signaling activation is required for glioblastoma pathogenesis

    PubMed Central

    Vitucci, Mark; Karpinich, Natalie O.; Bash, Ryan E.; Werneke, Andrea M.; Schmid, Ralf S.; White, Kristen K.; McNeill, Robert S.; Huff, Byron; Wang, Sophie; Van Dyke, Terry; Miller, C. Ryan

    2013-01-01

    Background Glioblastoma (GBM) genomes feature recurrent genetic alterations that dysregulate core intracellular signaling pathways, including the G1/S cell cycle checkpoint and the MAPK and PI3K effector arms of receptor tyrosine kinase (RTK) signaling. Elucidation of the phenotypic consequences of activated RTK effectors is required for the design of effective therapeutic and diagnostic strategies. Methods Genetically defined, G1/S checkpoint-defective cortical murine astrocytes with constitutively active Kras and/or Pten deletion mutations were used to systematically investigate the individual and combined roles of these 2 RTK signaling effectors in phenotypic hallmarks of glioblastoma pathogenesis, including growth, migration, and invasion in vitro. A novel syngeneic orthotopic allograft model system was used to examine in vivo tumorigenesis. Results Constitutively active Kras and/or Pten deletion mutations activated both MAPK and PI3K signaling. Their combination led to maximal growth, migration, and invasion of G1/S-defective astrocytes in vitro and produced progenitor-like transcriptomal profiles that mimic human proneural GBM. Activation of both RTK effector arms was required for in vivo tumorigenesis and produced highly invasive, proneural-like GBM. Conclusions These results suggest that cortical astrocytes can be transformed into GBM and that combined dysregulation of MAPK and PI3K signaling revert G1/S-defective astrocytes to a primitive gene expression state. This genetically-defined, immunocompetent model of proneural GBM will be useful for preclinical development of MAPK/PI3K-targeted, subtype-specific therapies. PMID:23814263

  5. Diversity of Active States in TMT Opsins

    PubMed Central

    Sakai, Kazumi; Yamashita, Takahiro; Imamoto, Yasushi; Shichida, Yoshinori

    2015-01-01

    Opn3/TMT opsins belong to one of the opsin groups with vertebrate visual and non-visual opsins, and are widely distributed in eyes, brains and other internal organs in various vertebrates and invertebrates. Vertebrate Opn3/TMT opsins are further classified into four groups on the basis of their amino acid identities. However, there is limited information about molecular properties of these groups, due to the difficulty in preparing the recombinant proteins. Here, we successfully expressed recombinant proteins of TMT1 and TMT2 opsins of medaka fish (Oryzias latipes) in cultured cells and characterized their molecular properties. Spectroscopic and biochemical studies demonstrated that TMT1 and TMT2 opsins functioned as blue light-sensitive Gi/Go-coupled receptors, but exhibited spectral properties and photo-convertibility of the active state different from each other. TMT1 opsin forms a visible light-absorbing active state containing all-trans-retinal, which can be photo-converted to 7-cis- and 9-cis-retinal states in addition to the original 11-cis-retinal state. In contrast, the active state of TMT2 opsin is a UV light-absorbing state having all-trans-retinal and does not photo-convert to any other state, including the original 11-cis-retinal state. Thus, TMT opsins are diversified so as to form a different type of active state, which may be responsible for their different functions. PMID:26491964

  6. Correspondence between Resting-State Activity and Brain Gene Expression.

    PubMed

    Wang, Guang-Zhong; Belgard, T Grant; Mao, Deng; Chen, Leslie; Berto, Stefano; Preuss, Todd M; Lu, Hanzhang; Geschwind, Daniel H; Konopka, Genevieve

    2015-11-18

    The relationship between functional brain activity and gene expression has not been fully explored in the human brain. Here, we identify significant correlations between gene expression in the brain and functional activity by comparing fractional amplitude of low-frequency fluctuations (fALFF) from two independent human fMRI resting-state datasets to regional cortical gene expression from a newly generated RNA-seq dataset and two additional gene expression datasets to obtain robust and reproducible correlations. We find significantly more genes correlated with fALFF than expected by chance and identify specific genes correlated with the imaging signals in multiple expression datasets in the default mode network. Together, these data support a population-level relationship between regional steady-state brain gene expression and resting-state brain activity. PMID:26590343

  7. Systematic identification of signal-activated stochastic gene regulation.

    PubMed

    Neuert, Gregor; Munsky, Brian; Tan, Rui Zhen; Teytelman, Leonid; Khammash, Mustafa; van Oudenaarden, Alexander

    2013-02-01

    Although much has been done to elucidate the biochemistry of signal transduction and gene regulatory pathways, it remains difficult to understand or predict quantitative responses. We integrate single-cell experiments with stochastic analyses, to identify predictive models of transcriptional dynamics for the osmotic stress response pathway in Saccharomyces cerevisiae. We generate models with varying complexity and use parameter estimation and cross-validation analyses to select the most predictive model. This model yields insight into several dynamical features, including multistep regulation and switchlike activation for several osmosensitive genes. Furthermore, the model correctly predicts the transcriptional dynamics of cells in response to different environmental and genetic perturbations. Because our approach is general, it should facilitate a predictive understanding for signal-activated transcription of other genes in other pathways or organisms. PMID:23372015

  8. Gq signaling causes glomerular injury by activating TRPC6

    PubMed Central

    Wang, Liming; Jirka, Grant; Rosenberg, Paul B.; Buckley, Anne F.; Gomez, Jose A.; Fields, Timothy A.; Winn, Michelle P.; Spurney, Robert F.

    2015-01-01

    Familial forms of focal segmental glomerulosclerosis (FSGS) have been linked to gain-of-function mutations in the gene encoding the transient receptor potential channel C6 (TRPC6). GPCRs coupled to Gq signaling activate TRPC6, suggesting that Gq-dependent TRPC6 activation underlies glomerular diseases. Here, we developed a murine model in which a constitutively active Gq α subunit (GqQ209L, referred to herein as GqQ>L) is specifically expressed in podocytes and examined the effects of this mutation in response to puromycin aminonucleoside (PAN) nephrosis. We found that compared with control animals, animals expressing GqQ>L exhibited robust albuminuria, structural features of FSGS, and reduced numbers of glomerular podocytes. Gq activation stimulated calcineurin (CN) activity, resulting in CN-dependent upregulation of TRPC6 in murine kidneys. Deletion of TRPC6 in GqQ>L-expressing mice prevented FSGS development and inhibited both tubular damage and podocyte loss induced by PAN nephrosis. Similarly, administration of the CN inhibitor FK506 reduced proteinuria and tubular injury but had more modest effects on glomerular pathology and podocyte numbers in animals with constitutive Gq activation. Moreover, these Gq-dependent effects on podocyte injury were generalizable to diabetic kidney disease, as expression of GqQ>L promoted albuminuria, mesangial expansion, and increased glomerular basement membrane width in diabetic mice. Together, these results suggest that targeting Gq/TRPC6 signaling may have therapeutic benefits for the treatment of glomerular diseases. PMID:25844902

  9. Akt-mTORC1 signaling regulates Acly to integrate metabolic input to control of macrophage activation

    PubMed Central

    Covarrubias, Anthony J; Aksoylar, Halil Ibrahim; Yu, Jiujiu; Snyder, Nathaniel W; Worth, Andrew J; Iyer, Shankar S; Wang, Jiawei; Ben-Sahra, Issam; Byles, Vanessa; Polynne-Stapornkul, Tiffany; Espinosa, Erika C; Lamming, Dudley; Manning, Brendan D; Zhang, Yijing; Blair, Ian A; Horng, Tiffany

    2016-01-01

    Macrophage activation/polarization to distinct functional states is critically supported by metabolic shifts. How polarizing signals coordinate metabolic and functional reprogramming, and the potential implications for control of macrophage activation, remains poorly understood. Here we show that IL-4 signaling co-opts the Akt-mTORC1 pathway to regulate Acly, a key enzyme in Ac-CoA synthesis, leading to increased histone acetylation and M2 gene induction. Only a subset of M2 genes is controlled in this way, including those regulating cellular proliferation and chemokine production. Moreover, metabolic signals impinge on the Akt-mTORC1 axis for such control of M2 activation. We propose that Akt-mTORC1 signaling calibrates metabolic state to energetically demanding aspects of M2 activation, which may define a new role for metabolism in supporting macrophage activation. DOI: http://dx.doi.org/10.7554/eLife.11612.001 PMID:26894960

  10. Chemical Signaling and Functional Activation in Colloidosome-Based Protocells.

    PubMed

    Sun, Shiyong; Li, Mei; Dong, Faqin; Wang, Shengjie; Tian, Liangfei; Mann, Stephen

    2016-04-13

    An aqueous-based microcompartmentalized model involving the integration of partially hydrophobic Fe(III)-rich montmorillonite (FeM) clay particles as structural and catalytic building blocks for colloidosome membrane assembly, self-directed membrane remodeling, and signal-induced protocell communication is described. The clay colloidosomes exhibit size- and charge-selective permeability, and show dual catalytic functions involving spatially confined enzyme-mediated dephosphorylation and peroxidase-like membrane activity. The latter is used for the colloidosome-mediated synthesis and assembly of a temperature-responsive poly(N-isopropylacrylamide)(PNIPAM)/clay-integrated hybrid membrane. In situ PNIPAM elaboration of the membrane is coupled to a glucose oxidase (GOx)-mediated signaling pathway to establish a primitive model of chemical communication and functional activation within a synthetic "protocell community" comprising a mixed population of GOx-containing silica colloidosomes and alkaline phosphatase (ALP)-containing FeM-clay colloidosomes. Triggering the enzyme reaction in the silica colloidosomes gives a hydrogen peroxide signal that induces polymer wall formation in a coexistent population of the FeM-clay colloidosomes, which in turn generates self-regulated membrane-gated ALP-activity within the clay microcompartments. The emergence of new functionalities in inorganic colloidosomes via chemical communication between different protocell populations provides a first step toward the realization of interacting communities of synthetic functional microcompartments. PMID:26923794

  11. Cortical membrane potential signature of optimal states for sensory signal detection

    PubMed Central

    McGinley, Matthew J.; David, Stephen V.; McCormick, David A.

    2015-01-01

    The neural correlates of optimal states for signal detection task performance are largely unknown. One hypothesis holds that optimal states exhibit tonically depolarized cortical neurons with enhanced spiking activity, such as occur during movement. We recorded membrane potentials of auditory cortical neurons in mice trained on a challenging tone-in-noise detection task while assessing arousal with simultaneous pupillometry and hippocampal recordings. Arousal measures accurately predicted multiple modes of membrane potential activity, including: rhythmic slow oscillations at low arousal, stable hyperpolarization at intermediate arousal, and depolarization during phasic or tonic periods of hyper-arousal. Walking always occurred during hyper-arousal. Optimal signal detection behavior and sound-evoked responses, at both sub-threshold and spiking levels, occurred at intermediate arousal when pre-decision membrane potentials were stably hyperpolarized. These results reveal a cortical physiological signature of the classically-observed inverted-U relationship between task performance and arousal, and that optimal detection exhibits enhanced sensory-evoked responses and reduced background synaptic activity. PMID:26074005

  12. Wnt Signaling Activates Shh Signaling in Early Postnatal Intervertebral Discs, and Re-Activates Shh Signaling in Old Discs in the Mouse

    PubMed Central

    Sinner, Debora; Wylie, Christopher C.; Dahia, Chitra Lekha

    2014-01-01

    Intervertebral discs (IVDs) are strong fibrocartilaginous joints that connect adjacent vertebrae of the spine. As discs age they become prone to failure, with neurological consequences that are often severe. Surgical repair of discs treats the result of the disease, which affects as many as one in seven people, rather than its cause. An ideal solution would be to repair degenerating discs using the mechanisms of their normal differentiation. However, these mechanisms are poorly understood. Using the mouse as a model, we previously showed that Shh signaling produced by nucleus pulposus cells activates the expression of differentiation markers, and cell proliferation, in the postnatal IVD. In the present study, we show that canonical Wnt signaling is required for the expression of Shh signaling targets in the IVD. We also show that Shh and canonical Wnt signaling pathways are down-regulated in adult IVDs. Furthermore, this down-regulation is reversible, since re-activation of the Wnt or Shh pathways in older discs can re-activate molecular markers of the IVD that are lost with age. These data suggest that biological treatments targeting Wnt and Shh signaling pathways may be feasible as a therapeutic for degenerative disc disease. PMID:24892825

  13. Exploiting the yeast stress-activated signaling network to inform on stress biology and disease signaling

    PubMed Central

    Ho, Yi-Hsuan

    2016-01-01

    Healthy cells utilize intricate systems to monitor their environment and mount robust responses in the event of cellular stress. Whether stress arises from external insults or defects due to mutation and disease, cells must be able to respond precisely to mount the appropriate defenses. Multi-faceted stress responses are generally coupled with arrest of growth and cell-cycle progression, which both limits the transmission of damaged materials and serves to reallocate limited cellular resources toward defense. Therefore, stress defense versus rapid growth represent competing interests in the cell. How eukaryotic cells set the balance between defense versus proliferation, and in particular knowledge of the regulatory networks that control this decision, are poorly understood. In this perspective, we expand upon our recent work inferring the stress-activated signaling network in budding yeast, which captures pathways controlling stress defense and regulators of growth and cell-cycle progression. We highlight similarities between the yeast and mammalian stress responses and explore how stress-activated signaling networks in yeast can inform on signaling defects in human cancers. PMID:25957506

  14. Single Particle Tracking Reveals that EGFR Signaling Activity Is Amplified in Clathrin-Coated Pits

    PubMed Central

    Ibach, Jenny; Radon, Yvonne; Gelléri, Márton; Sonntag, Michael H.; Brunsveld, Luc; Bastiaens, Philippe I. H.; Verveer, Peter J.

    2015-01-01

    Signaling from the epidermal growth factor receptor (EGFR) via phosphorylation on its C-terminal tyrosine residues requires self-association, which depends on the diffusional properties of the receptor and its density in the plasma membrane. Dimerization is a key event for EGFR activation, but the role of higher order clustering is unknown. We employed single particle tracking to relate the mobility and aggregation of EGFR to its signaling activity. EGFR mobility alternates between short-lived free, confined and immobile states. In the immobile state, EGFR tends to aggregate in clathrin-coated pits, which is further enhanced in a phosphorylation-dependent manner and does not require ligand binding. EGFR phosphorylation is further amplified by cross-phosphorylation in clathrin-coated pits. Because phosphorylated receptors can escape from the pits, local gradients of signaling active EGFR are formed. These results show that amplification of EGFR phosphorylation by receptor clustering in clathrin-coated pits supports signal activation at the plasma membrane. PMID:26575183

  15. Single molecule analysis of B cell receptor motion during signaling activation

    NASA Astrophysics Data System (ADS)

    Rey Suarez, Ivan; Koo, Peter; Mochrie, Simon; Song, Wenxia; Upadhyaya, Arpita

    B cells are an essential part of the adaptive immune system. They patrol the body looking for signs of infection in the form of antigen on the surface of antigen presenting cells. The binding of the B cell receptor (BCR) to antigen induces signaling cascades that lead to B cell activation and eventual production of high affinity antibodies. During activation, BCR organize into signaling microclusters, which are platforms for signal amplification. The physical processes underlying receptor movement and aggregation are not well understood. Here we study the dynamics of single BCRs on activated murine primary B cells using TIRF imaging and single particle tracking. The tracks obtained are analyzed using perturbation expectation-maximization (pEM) a systems-level analysis that allows the identification of different short-time diffusive states from a set of single particle tracks. We identified five different diffusive states on wild type cells, which correspond to different molecular states of the BCR. By using actin polymerization inhibitors and mutant cells lacking important actin regulators we were able to identify the BCR molecule configuration associated with each diffusive state.

  16. Light activated solid-state opening switches

    SciTech Connect

    Petr, R.A.; Kachen, G.I.; Reilly, J.P.; Schaefer, R.B. ); Heyse, M.W. )

    1993-01-01

    Light-activated solid-state opening switches are shown to be a viable approach for switching inductive circuits. Measured photoswitch performance indicates that light-activated opening switches have the power density ratings needed to develop compact inductive power systems.

  17. Light activated solid-state opening switches

    NASA Astrophysics Data System (ADS)

    Petr, R. A.; Kachen, G. I.; Reilly, J. P.; Schaefer, R. B.; Heyse, M. W.

    1993-01-01

    The paper shows light-activated solid-state opening switches to be a viable approach for switching inductive circuits. Measured photoswitch performance indicates that light-activated opening switches have the power density ratings required to develop compact inductive power systems.

  18. Notum deacylates Wnt proteins to suppress signalling activity.

    PubMed

    Kakugawa, Satoshi; Langton, Paul F; Zebisch, Matthias; Howell, Steven A; Chang, Tao-Hsin; Liu, Yan; Feizi, Ten; Bineva, Ganka; O'Reilly, Nicola; Snijders, Ambrosius P; Jones, E Yvonne; Vincent, Jean-Paul

    2015-03-12

    Signalling by Wnt proteins is finely balanced to ensure normal development and tissue homeostasis while avoiding diseases such as cancer. This is achieved in part by Notum, a highly conserved secreted feedback antagonist. Notum has been thought to act as a phospholipase, shedding glypicans and associated Wnt proteins from the cell surface. However, this view fails to explain specificity, as glypicans bind many extracellular ligands. Here we provide genetic evidence in Drosophila that Notum requires glypicans to suppress Wnt signalling, but does not cleave their glycophosphatidylinositol anchor. Structural analyses reveal glycosaminoglycan binding sites on Notum, which probably help Notum to co-localize with Wnt proteins. They also identify, at the active site of human and Drosophila Notum, a large hydrophobic pocket that accommodates palmitoleate. Kinetic and mass spectrometric analyses of human proteins show that Notum is a carboxylesterase that removes an essential palmitoleate moiety from Wnt proteins and thus constitutes the first known extracellular protein deacylase. PMID:25731175

  19. Pathway connectivity and signaling coordination in the yeast stress-activated signaling network

    PubMed Central

    Chasman, Deborah; Ho, Yi-Hsuan; Berry, David B; Nemec, Corey M; MacGilvray, Matthew E; Hose, James; Merrill, Anna E; Lee, M Violet; Will, Jessica L; Coon, Joshua J; Ansari, Aseem Z; Craven, Mark; Gasch, Audrey P

    2014-01-01

    Stressed cells coordinate a multi-faceted response spanning many levels of physiology. Yet knowledge of the complete stress-activated regulatory network as well as design principles for signal integration remains incomplete. We developed an experimental and computational approach to integrate available protein interaction data with gene fitness contributions, mutant transcriptome profiles, and phospho-proteome changes in cells responding to salt stress, to infer the salt-responsive signaling network in yeast. The inferred subnetwork presented many novel predictions by implicating new regulators, uncovering unrecognized crosstalk between known pathways, and pointing to previously unknown ‘hubs’ of signal integration. We exploited these predictions to show that Cdc14 phosphatase is a central hub in the network and that modification of RNA polymerase II coordinates induction of stress-defense genes with reduction of growth-related transcripts. We find that the orthologous human network is enriched for cancer-causing genes, underscoring the importance of the subnetwork's predictions in understanding stress biology. PMID:25411400

  20. Angiotensin II activates different calcium signaling pathways in adipocytes.

    PubMed

    Dolgacheva, Lyudmila P; Turovskaya, Maria V; Dynnik, Vladimir V; Zinchenko, Valery P; Goncharov, Nikolay V; Davletov, Bazbek; Turovsky, Egor A

    2016-03-01

    Angiotensin II (Ang II) is an important mammalian neurohormone involved in reninangiotensin system. Ang II is produced both constitutively and locally by RAS systems, including white fat adipocytes. The influence of Ang II on adipocytes is complex, affecting different systems of signal transduction from early Са(2+) responses to cell proliferation and differentiation, triglyceride accumulation, expression of adipokine-encoding genes and adipokine secretion. It is known that white fat adipocytes express all RAS components and Ang II receptors (АТ1 and АТ2). The current work was carried out with the primary white adipocytes culture, and Са(2+) signaling pathways activated by Ang II were investigated using fluorescent microscopy. Са(2+)-oscillations and transient responses of differentiated adipocytes to Ang II were registered in cells with both small and multiple lipid inclusions. Using inhibitory analysis and selective antagonists, we now show that Ang II initiates periodic Са(2+)-oscillations and transient responses by activating АТ1 and АТ2 receptors and involving branched signaling cascades: 1) Ang II → Gq → PLC → IP3 → IP3Rs → Ca(2+) 2) Gβγ → PI3Kγ → PKB 3) PKB → eNOS → NO → PKG 4) CD38 → cADPR → RyRs → Ca(2+) In these cascades, AT1 receptors play the leading role. The results of the present work open a perspective of using Ang II for correction of signal resistance of adipocytes often observed during obesity and type 2 diabetes. PMID:26850364

  1. Mitogen Activated Protein kinase signal transduction pathways in the prostate

    PubMed Central

    Maroni, Paul D; Koul, Sweaty; Meacham, Randall B; Koul, Hari K

    2004-01-01

    The biochemistry of the mitogen activated protein kinases ERK, JNK, and p38 have been studied in prostate physiology in an attempt to elucidate novel mechanisms and pathways for the treatment of prostatic disease. We reviewed articles examining mitogen-activated protein kinases using prostate tissue or cell lines. As with other tissue types, these signaling modules are links/transmitters for important pathways in prostate cells that can result in cellular survival or apoptosis. While the activation of the ERK pathway appears to primarily result in survival, the roles of JNK and p38 are less clear. Manipulation of these pathways could have important implications for the treatment of prostate cancer and benign prostatic hypertrophy. PMID:15219238

  2. Digital signaling decouples activation probability and population heterogeneity

    PubMed Central

    Kellogg, Ryan A; Tian, Chengzhe; Lipniacki, Tomasz; Quake, Stephen R; Tay, Savaş

    2015-01-01

    Digital signaling enhances robustness of cellular decisions in noisy environments, but it is unclear how digital systems transmit temporal information about a stimulus. To understand how temporal input information is encoded and decoded by the NF-κB system, we studied transcription factor dynamics and gene regulation under dose- and duration-modulated inflammatory inputs. Mathematical modeling predicted and microfluidic single-cell experiments confirmed that integral of the stimulus (or area, concentration × duration) controls the fraction of cells that activate NF-κB in the population. However, stimulus temporal profile determined NF-κB dynamics, cell-to-cell variability, and gene expression phenotype. A sustained, weak stimulation lead to heterogeneous activation and delayed timing that is transmitted to gene expression. In contrast, a transient, strong stimulus with the same area caused rapid and uniform dynamics. These results show that digital NF-κB signaling enables multidimensional control of cellular phenotype via input profile, allowing parallel and independent control of single-cell activation probability and population heterogeneity. DOI: http://dx.doi.org/10.7554/eLife.08931.001 PMID:26488364

  3. Digital signaling decouples activation probability and population heterogeneity.

    PubMed

    Kellogg, Ryan A; Tian, Chengzhe; Lipniacki, Tomasz; Quake, Stephen R; Tay, Savaş

    2015-01-01

    Digital signaling enhances robustness of cellular decisions in noisy environments, but it is unclear how digital systems transmit temporal information about a stimulus. To understand how temporal input information is encoded and decoded by the NF-κB system, we studied transcription factor dynamics and gene regulation under dose- and duration-modulated inflammatory inputs. Mathematical modeling predicted and microfluidic single-cell experiments confirmed that integral of the stimulus (or area, concentration × duration) controls the fraction of cells that activate NF-κB in the population. However, stimulus temporal profile determined NF-κB dynamics, cell-to-cell variability, and gene expression phenotype. A sustained, weak stimulation lead to heterogeneous activation and delayed timing that is transmitted to gene expression. In contrast, a transient, strong stimulus with the same area caused rapid and uniform dynamics. These results show that digital NF-κB signaling enables multidimensional control of cellular phenotype via input profile, allowing parallel and independent control of single-cell activation probability and population heterogeneity. PMID:26488364

  4. Activity-Based Probe for Histidine Kinase Signaling

    PubMed Central

    Wilke, Kaelyn E.; Francis, Samson; Carlson, Erin E.

    2012-01-01

    Bacterial two-component systems (TCSs) are signaling pathways composed of two proteins, a histidine kinase (HK) and a response regulator (RR). Upon stimulation, the HK autophosphorylates at a conserved histidine. The phosphoryl group is subsequently transferred to an aspartate on a RR, eliciting an adaptive response, often up- or downregulation of gene expression. TCS signaling controls many functions in bacteria including development, virulence and antibiotic resistance, making the proteins involved in these systems potential therapeutic targets. Efficient methods for the profiling of HKs are currently lacking. For direct readout of HK activity, we sought to design a probe that enables detection of the phosphotransfer event; however, analysis of the phosphohistidine species is made difficult by the instability of the P-N bond. We anticipated that use of a γ-thiophosphorylated ATP analog, which would yield a thiophosphorylated histidine intermediate, could overcome this challenge. We determined that the fluorophore-conjugated probe, ATPγS-BODIPY, labels active HK proteins and is competitive for the ATP-binding site. This activity-based probe provides a new strategy for analysis of TCSs and other HK-mediated processes and will facilitate both functional studies and inhibitor identification. PMID:22606938

  5. Digital Signal Processing System for Active Noise Reduction

    NASA Astrophysics Data System (ADS)

    Edmonson, William W.; Tucker, Jerry

    2002-12-01

    Over the years there has been a need to improve the comfort of passengers in flight. One avenue for increasing comfort is to reduce cabin noise that is attributed to the engine and the vibration of fuselage panels that radiate sound. High frequency noise can be abated using sound absorbing material. Though, for low frequency noise the sound absorption material would have to very thick, thereby reducing the cabin size. To reduce these low frequency disturbances, active noise control systems (ANC) is being developed that utilizes feedback for cancellation of the disturbance. The active noise control system must be small in size, be a low power device, and operate in real-time. It must also be numerically stable i.e. insensitive to temperature and pressure variations. The ANC system will be a module that consists of digital signal processor (DSP), analog-digital and digital-analog converters, power converters, an actuator and sensors. The DSP will implement the feedback control algorithm that controls the actuators. This module will be attached to panels on the inside of the fuselage for actively eliminating resonant modes of the structure caused by turbulent flow across the fuselage Skin. A hardware prototype of the ANC system must be able to eliminate broadband noise consisting of a bandwidth between 100 Hz and 1500 Hz, which requires a sample rate of 5000 Hz. The analog/digital converters output accuracy is 16 bits with a 2's-compliment format and a very short acquisition time. This will also yield the appropriate dynamic range. Similar specifications are required of the digital/analog converter. The processor section of the system integrates a digital signal processor (TI TMS320C33) with analog/digital (Burr-Brown ADS8320) and digital/analog signal (DAC853 1) converters. The converters with associated power conditioning circuitry and test points reside on a daughter board that sits on top of a Spectrum Digital evaluation module. This will have the ability to test

  6. The role of the Janus kinase family/signal transducer and activator of transcription signaling pathway in fibrotic renal disease

    PubMed Central

    Matsui, Futoshi; Meldrum, Kirstan K.

    2012-01-01

    Over the past several years, a number of cytokines and growth factors including transforming growth factor β1, tumor necrosis factor α, and angiotensin II have been shown to play a crucial role in renal fibrosis. The Janus kinase family (JAK) and signal transducers and activators of transcription (STATs) constitute one of the primary signaling pathways that regulate cytokine expression, and the JAK/STAT signaling pathway has increasingly been implicated in the pathophysiology of renal disease. This review examines the role of the JAK/STAT signaling pathway in fibrotic renal disease. The JAK/STAT signaling pathway is activated in a variety of renal diseases and has been implicated in the pathophysiology of renal fibrosis. Experimental evidence suggests that inhibition of the JAK/STAT signaling pathway, in particular JAK2 and STAT3, may suppress renal fibrosis and protect renal function. However, it is incompletely understood which cells activate the JAK/STAT signaling pathway and which JAK/STAT signaling pathway is activated in each renal disease. Research regarding JAK/STAT signaling and its contribution to renal disease is still ongoing in humans. Future studies are required to elucidate the potential role of JAK/STAT signaling inhibition as a therapeutic strategy in the attenuation of renal fibrosis. PMID:22883438

  7. Role of Calcium Signaling in B Cell Activation and Biology.

    PubMed

    Baba, Yoshihiro; Kurosaki, Tomohiro

    2016-01-01

    Increase in intracellular levels of calcium ions (Ca2+) is one of the key triggering signals for the development of B cell response to the antigen. The diverse Ca2+ signals finely controlled by multiple factors participate in the regulation of gene expression, B cell development, and effector functions. B cell receptor (BCR)-initiated Ca2+ mobilization is sourced from two pathways: one is the release of Ca2+ from the intracellular stores, endoplasmic reticulum (ER), and other is the prolonged influx of extracellular Ca2+ induced by depleting the stores via store-operated calcium entry (SOCE) and calcium release-activated calcium (CRAC) channels. The identification of stromal interaction molecule 1(STIM1), the ER Ca2+ sensor, and Orai1, a key subunit of the CRAC channel pore, has now provided the tools to understand the mode of Ca2+ influx regulation and physiological relevance. Herein, we discuss our current understanding of the molecular mechanisms underlying BCR-triggered Ca2+ signaling as well as its contribution to the B cell biological processes and diseases. PMID:26369772

  8. Personalizing energy expenditure estimation using physiological signals normalization during activities of daily living.

    PubMed

    Altini, Marco; Penders, Julien; Vullers, Ruud; Amft, Oliver

    2014-09-01

    In this paper we propose a generic approach to reduce inter-individual variability of different physiological signals (HR, GSR and respiration) by automatically estimating normalization parameters (e.g. baseline and range). The proposed normalization procedure does not require a dedicated personal calibration during system setup. On the other hand, normalization parameters are estimated at system runtime from sedentary and low intensity activities of daily living (ADLs), such as lying and walking. When combined with activity-specific energy expenditure (EE) models, our normalization procedure improved EE estimation by 15 to 33% in a study group of 18 participants, compared to state of the art activity-specific EE models combining accelerometer and non-normalized physiological signals. PMID:25120177

  9. Calcium-Oxidant Signaling Network Regulates AMP-activated Protein Kinase (AMPK) Activation upon Matrix Deprivation*

    PubMed Central

    Sundararaman, Ananthalakshmy; Amirtham, Usha; Rangarajan, Annapoorni

    2016-01-01

    The AMP-activated protein kinase (AMPK) has recently been implicated in anoikis resistance. However, the molecular mechanisms that activate AMPK upon matrix detachment remain unexplored. In this study, we show that AMPK activation is a rapid and sustained phenomenon upon matrix deprivation, whereas re-attachment to the matrix leads to its dephosphorylation and inactivation. Because matrix detachment leads to loss of integrin signaling, we investigated whether integrin signaling negatively regulates AMPK activation. However, modulation of focal adhesion kinase or Src, the major downstream components of integrin signaling, failed to cause a corresponding change in AMPK signaling. Further investigations revealed that the upstream AMPK kinases liver kinase B1 (LKB1) and Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ) contribute to AMPK activation upon detachment. In LKB1-deficient cells, we found AMPK activation to be predominantly dependent on CaMKKβ. We observed no change in ATP levels under detached conditions at early time points suggesting that rapid AMPK activation upon detachment was not triggered by energy stress. We demonstrate that matrix deprivation leads to a spike in intracellular calcium as well as oxidant signaling, and both these intracellular messengers contribute to rapid AMPK activation upon detachment. We further show that endoplasmic reticulum calcium release-induced store-operated calcium entry contributes to intracellular calcium increase, leading to reactive oxygen species production, and AMPK activation. We additionally show that the LKB1/CaMKK-AMPK axis and intracellular calcium levels play a critical role in anchorage-independent cancer sphere formation. Thus, the Ca2+/reactive oxygen species-triggered LKB1/CaMKK-AMPK signaling cascade may provide a quick, adaptable switch to promote survival of metastasizing cancer cells. PMID:27226623

  10. Biomechanical Signals Suppress TAK1 Activation to Inhibit NF-κB Transcriptional Activation in Fibrochondrocytes

    PubMed Central

    Madhavan, Shashi; Anghelina, Mirela; Sjostrom, Danen; Dossumbekova, Anar; Guttridge, Denis C.; Agarwal, Sudha

    2016-01-01

    Exercise/joint mobilization is therapeutic for inflammatory joint diseases like rheumatoid and osteoarthritis, but the mechanisms underlying its actions remain poorly understood. We report that biomechanical signals at low/physiological magnitudes are potent inhibitors of inflammation induced by diverse proinflammatory activators like IL-1β, TNF-α, and lipopolysaccharides, in fibrochondrocytes. These signals exert their anti-inflammatory effects by inhibiting phosphorylation of TAK1, a critical point where signals generated by IL-1β, TNF-α, and LPS converge to initiate NF-κB signaling cascade and proinflammatory gene induction. Additionally, biomechanical signals inhibit multiple steps in the IL-1β-induced proinflammatory cascade downstream of IκB kinase activation to regulate IκBα and IκBβ degradation and synthesis, and promote IκBα shuttling to export nuclear NF-κB and terminate its transcriptional activity. The findings demonstrate that biomechanical forces are but another important signal that uses NF-κB pathway to regulate inflammation by switching the molecular activation of discrete molecules involved in proinflammatory gene transcription. PMID:17947700

  11. Transsynaptic signaling by activity-dependent cleavage of neuroligin-1.

    PubMed

    Peixoto, Rui T; Kunz, Portia A; Kwon, Hyungbae; Mabb, Angela M; Sabatini, Bernardo L; Philpot, Benjamin D; Ehlers, Michael D

    2012-10-18

    Adhesive contact between pre- and postsynaptic neurons initiates synapse formation during brain development and provides a natural means of transsynaptic signaling. Numerous adhesion molecules and their role during synapse development have been described in detail. However, once established, the mechanisms of adhesive disassembly and its function in regulating synaptic transmission have been unclear. Here, we report that synaptic activity induces acute proteolytic cleavage of neuroligin-1 (NLG1), a postsynaptic adhesion molecule at glutamatergic synapses. NLG1 cleavage is triggered by NMDA receptor activation, requires Ca2+ /calmodulin-dependent protein kinase, and is mediated by proteolytic activity of matrix metalloprotease 9 (MMP9). Cleavage of NLG1 occurs at single activated spines, is regulated by neural activity in vivo, and causes rapid destabilization of its presynaptic partner neurexin-1β (NRX1β). In turn, NLG1 cleavage depresses synaptic transmission by abruptly reducing presynaptic release probability. Thus, local proteolytic control of synaptic adhesion tunes synaptic transmission during brain development and plasticity. PMID:23083741

  12. An apodized Kepler periodogram for separating planetary and stellar activity signals

    NASA Astrophysics Data System (ADS)

    Gregory, Philip C.

    2016-05-01

    A new apodized Keplerian (AK) model is proposed for the analysis of precision radial velocity (RV) data to model both planetary and stellar activity (SA) induced RV signals. A symmetrical Gaussian apodization function with unknown width and centre can distinguish planetary signals from SA signals on the basis of the span of the apodization window. The general model for m AK signals includes a linear regression term between RV and the SA diagnostic log (R'hk), as well as an extra Gaussian noise term with unknown standard deviation. The model parameters are explored using a Bayesian fusion Markov chain Monte Carlo code. A differential version of the generalized Lomb-Scargle periodogram that employs a control diagnostic provides an additional way of distinguishing SA signals and helps guide the choice of new periods. Results are reported for a recent international RV blind challenge which included multiple state-of-the-art simulated data sets supported by a variety of SA diagnostics. In the current implementation, the AK method achieved a reduction in SA noise by a factor of approximately 6. Final parameter estimates for the planetary candidates are derived from fits that include AK signals to model the SA components and simple Keplerians to model the planetary candidates. Preliminary results are also reported for AK models augmented by a moving average component that allows for correlations in the residuals.

  13. An apodized Kepler periodogram for separating planetary and stellar activity signals

    PubMed Central

    Gregory, Philip C.

    2016-01-01

    A new apodized Keplerian (AK) model is proposed for the analysis of precision radial velocity (RV) data to model both planetary and stellar activity (SA) induced RV signals. A symmetrical Gaussian apodization function with unknown width and centre can distinguish planetary signals from SA signals on the basis of the span of the apodization window. The general model for m AK signals includes a linear regression term between RV and the SA diagnostic log (R′hk), as well as an extra Gaussian noise term with unknown standard deviation. The model parameters are explored using a Bayesian fusion Markov chain Monte Carlo code. A differential version of the generalized Lomb–Scargle periodogram that employs a control diagnostic provides an additional way of distinguishing SA signals and helps guide the choice of new periods. Results are reported for a recent international RV blind challenge which included multiple state-of-the-art simulated data sets supported by a variety of SA diagnostics. In the current implementation, the AK method achieved a reduction in SA noise by a factor of approximately 6. Final parameter estimates for the planetary candidates are derived from fits that include AK signals to model the SA components and simple Keplerians to model the planetary candidates. Preliminary results are also reported for AK models augmented by a moving average component that allows for correlations in the residuals. PMID:27346979

  14. IL-1 signaling modulates STAT activation to antagonize retinoic acid signaling and control Th17–iTreg balance

    PubMed Central

    Basu, Rajatava; Whitley, Sarah K.; Bhaumik, Suniti; Zindl, Carlene L.; Schoeb, Trenton R.; Benveniste, Etty N.; Pear, Warren S.; Hatton, Robin D.; Weaver, Casey T.

    2016-01-01

    Interleukin 17 (IL-17)-producing helper (TH17) and inducible regulatory CD4+ T (iTreg) cells emerge from an overlapping developmental program. In the intestines, the vitamin A metabolite retinoic acid (RA) is produced at steady state and acts as an important cofactor to induce iTreg cell development while potently inhibiting TH17 development. Here, we found that IL-1 was required to fully override RA-mediated Foxp3 expression and induce protective TH17 responses. Through induction of an NF-κB-dependent repression of SOCS3 expression, IL-1 increased the amplitude and duration of STAT3 phosphorylation induced by TH17-polarizing cytokines, leading to an altered balance of STAT3–STAT5 binding to shared consensus sequences in developing T cells. Thus, IL-1 signaling differentially modulated STAT activation downstream of cytokine receptors to control TH17–iTreg developmental fate. PMID:25642823

  15. Ceramide Signaling and Metabolism in Pathophysiological States of the Lung.

    PubMed

    Petrache, Irina; Berdyshev, Evgeny V

    2016-01-01

    Following the discovery of ceramide as the central signaling and metabolic relay among sphingolipids, studies of its involvement in lung health and pathophysiology have exponentially increased. In this review, we highlight key studies in the context of recent progress in metabolomics and translational research methodologies. Evidence points toward an important role for the ceramide/sphingosine-1-phosphate rheostat in maintaining lung cell survival, vascular barrier function, and proper host response to airway microbial infections. Sphingosine kinase 1 has emerged as an important determinant of sphingosine-1-phosphate lung levels, which, when aberrantly high, contribute to lung fibrosis, maladaptive vascular remodeling, and allergic asthma. New sphingolipid metabolites have been discovered as potential biomarkers of several lung diseases. Although multiple acute and chronic lung pathological conditions involve perturbations in sphingolipid signaling and metabolism, there are specific patterns, unique sphingolipid species, enzymes, metabolites, and receptors, which have emerged that deepen our understanding of lung pathophysiology and inform the development of new therapies for lung diseases. PMID:26667073

  16. A novel nuclear export signal in Smad1 is essential for its signaling activity.

    PubMed

    Xiao, Zhan; Brownawell, Amy M; Macara, Ian G; Lodish, Harvey F

    2003-09-01

    To investigate the subcellular distributions of Smad proteins, the intracellular mediators of transforming growth factor-beta family cytokines, we examined their sequences for nuclear export signals (NES). We found a leucine-rich NES-like motif (termed NES2) in the central linker region of the receptor-regulated Smads that is absent from the other two classes of Smads (Co-Smads and I-Smads). In microinjection assays, NES2 peptide caused nuclear export of a fused glutathione S-transferase protein. Mutations in NES2 converted Smad1 from an even distribution throughout the cells into an exclusive nuclear localization in both transiently and stably expressing cell lines, and this nuclear enrichment was more pronounced than that induced by mutations in NES1. Furthermore, overexpression of CRM1, the cellular export receptor, transforms Smad1 into a mostly cytoplasmic profile by enhancing its nuclear export. The Smad1 NES2 mutant but not the Smad1 NES1 mutant is mostly resistant to this cytoplasmic targeting, indicating that NES2, not NES1, is the major target for CRM1 in Smad1. We further confirmed the functionality of NES2 by a heterokaryon assay. The Smad1 NES1 mutant displays good ligand responsiveness and moderately lowered transcriptional activity compared with wild type Smad1. In contrast, the Smad1 NES2 mutant shows a severe disruption in reporter gene activation, minimal response to bone morphogenetic protein stimulation, and significantly lowered bone morphogenetic protein-induced phosphorylation, which may be the reason for its deficient transcription activity. Thus, we have defined a major NES in Smad1 that is essential for its ligand-induced coupling with cell surface receptors and hence, transcriptional activity. Our study, along with recent studies of the nucleocytoplasmic shuttling of Smad2 and Smad3 proteins, demonstrate that continued nucleocytoplasmic shuttling is a common requisite for the active signaling of R-Smads. Although conserved in other R

  17. Signal Transducer and Activator of Transcription-3, Inflammation, and Cancer

    PubMed Central

    Aggarwal, Bharat B.; Kunnumakkara, Ajaikumar B.; Harikumar, Kuzhuvelil B.; Gupta, Shan R.; Tharakan, Sheeja T.; Koca, Cemile; Dey, Sanjit; Sung, Bokyung

    2011-01-01

    Signal transducer and activator of transcription-3 (STAT-3) is one of six members of a family of transcription factors. It was discovered almost 15 years ago as an acute-phase response factor. This factor has now been associated with inflammation, cellular transformation, survival, proliferation, invasion, angiogenesis, and metastasis of cancer. Various types of carcinogens, radiation, viruses, growth factors, oncogenes, and inflammatory cytokines have been found to activate STAT-3. STAT-3 is constitutively active in most tumor cells but not in normal cells. Phosphorylation of STAT-3 at tyrosine 705 leads to its dimerization, nuclear translocation, DNA binding, and gene transcription. The phosphorylation of STAT-3 at serine 727 may regulate its activity negatively or positively. STAT-3 regulates the expression of genes that mediate survival (survivin, bcl-xl, mcl-1, cellular FLICE-like inhibitory protein), proliferation (c-fos, c-myc, cyclin D1), invasion (matrix metalloproteinase-2), and angiogenesis (vascular endothelial growth factor). STAT-3 activation has also been associated with both chemoresistance and radioresistance. STAT-3 mediates these effects through its collaboration with various other transcription factors, including nuclear factor-κB, hypoxia-inducible factor-1, and peroxisome proliferator activated receptor-γ. Because of its critical role in tumorigenesis, inhibitors of this factor’s activation are being sought for both prevention and therapy of cancer. This has led to identification of small peptides, oligonucleotides, and small molecules as potential STAT-3 inhibitors. Several of these small molecules are chemo-preventive agents derived from plants. This review discusses the intimate relationship between STAT-3, inflammation, and cancer in more detail. PMID:19723038

  18. Dynamic neural activity during stress signals resilient coping.

    PubMed

    Sinha, Rajita; Lacadie, Cheryl M; Constable, R Todd; Seo, Dongju

    2016-08-01

    Active coping underlies a healthy stress response, but neural processes supporting such resilient coping are not well-known. Using a brief, sustained exposure paradigm contrasting highly stressful, threatening, and violent stimuli versus nonaversive neutral visual stimuli in a functional magnetic resonance imaging (fMRI) study, we show significant subjective, physiologic, and endocrine increases and temporally related dynamically distinct patterns of neural activation in brain circuits underlying the stress response. First, stress-specific sustained increases in the amygdala, striatum, hypothalamus, midbrain, right insula, and right dorsolateral prefrontal cortex (DLPFC) regions supported the stress processing and reactivity circuit. Second, dynamic neural activation during stress versus neutral runs, showing early increases followed by later reduced activation in the ventrolateral prefrontal cortex (VLPFC), dorsal anterior cingulate cortex (dACC), left DLPFC, hippocampus, and left insula, suggested a stress adaptation response network. Finally, dynamic stress-specific mobilization of the ventromedial prefrontal cortex (VmPFC), marked by initial hypoactivity followed by increased VmPFC activation, pointed to the VmPFC as a key locus of the emotional and behavioral control network. Consistent with this finding, greater neural flexibility signals in the VmPFC during stress correlated with active coping ratings whereas lower dynamic activity in the VmPFC also predicted a higher level of maladaptive coping behaviors in real life, including binge alcohol intake, emotional eating, and frequency of arguments and fights. These findings demonstrate acute functional neuroplasticity during stress, with distinct and separable brain networks that underlie critical components of the stress response, and a specific role for VmPFC neuroflexibility in stress-resilient coping. PMID:27432990

  19. Functional Near-Infrared Spectroscopy Signals Measure Neuronal Activity in the Cortex

    NASA Technical Reports Server (NTRS)

    Harrivel, Angela; Hearn, Tristan

    2013-01-01

    Functional near infrared spectroscopy (fNIRS) is an emerging optical neuroimaging technology that indirectly measures neuronal activity in the cortex via neurovascular coupling. It quantifies hemoglobin concentration ([Hb]) and thus measures the same hemodynamic response as functional magnetic resonance imaging (fMRI), but is portable, non-confining, relatively inexpensive, and is appropriate for long-duration monitoring and use at the bedside. Like fMRI, it is noninvasive and safe for repeated measurements. Patterns of [Hb] changes are used to classify cognitive state. Thus, fNIRS technology offers much potential for application in operational contexts. For instance, the use of fNIRS to detect the mental state of commercial aircraft operators in near real time could allow intelligent flight decks of the future to optimally support human performance in the interest of safety by responding to hazardous mental states of the operator. However, many opportunities remain for improving robustness and reliability. It is desirable to reduce the impact of motion and poor optical coupling of probes to the skin. Such artifacts degrade signal quality and thus cognitive state classification accuracy. Field application calls for further development of algorithms and filters for the automation of bad channel detection and dynamic artifact removal. This work introduces a novel adaptive filter method for automated real-time fNIRS signal quality detection and improvement. The output signal (after filtering) will have had contributions from motion and poor coupling reduced or removed, thus leaving a signal more indicative of changes due to hemodynamic brain activations of interest. Cognitive state classifications based on these signals reflect brain activity more reliably. The filter has been tested successfully with both synthetic and real human subject data, and requires no auxiliary measurement. This method could be implemented as a real-time filtering option or bad channel

  20. Activation of MAP kinase signaling pathway in the mussel Mytilus galloprovincialis as biomarker of environmental pollution.

    PubMed

    Châtel, A; Hamer, B; Talarmin, H; Dorange, G; Schröder, H C; Müller, W E G

    2010-03-01

    Stimulation of MAP kinase signal transduction pathway by various stressful stimuli was investigated in the marine bivalve Mytilus galloprovincialis. Analyses were performed in animals exposed in laboratory to selected pollutants and in mussels collected in winter and summer along the eastern Adriatic coast (Croatia). Effects of oxidative stress, induced by tributyltin, hydrogen peroxide and water soluble fraction of diesel fuel on the activation/phosphorylation of the three Mitogen-Activated Protein Kinases (MAPKs) p38, JNK and ERK using a newly developed ELISA procedure were evaluated. MAP kinase activation was analyzed 1h after exposure of mussels to chemical agents, and after recovery periods of 6 and 24h. Our results clearly indicated that pollutants generated different patterns of induction of the MAPK phosphorylation. Indeed, only pp38 and pJNK were activated with 11, 33 and 100 microg/L TBT, reaching a maximum activation after 6h in seawater following treatment of mussels with 11 microg/L TBT. Treatment with 0.074 and 0.222 mM H2O2 enhanced activation of both p38 and ERK. These two kinases were activated after 1h exposure, followed by a diminution after 6h of recovery in seawater and a reactivation after 24h. The levels of phosphorylated P38 and JNK were increased after mussel exposure with 7.5, 15 and 30% of water soluble fraction of diesel oil. P38 was activated concentration dependently at 1h exposure. Additionally, field study pointed out seasonal differences in MAP kinases activation as mussels collected during summer had a higher enzyme activation state than in winter, as well as sampling site differences which could be correlated to the industrial/tourism activity and environmental stresses (salinity). All the results converge towards MAP kinase signaling pathway being induced by various pollutants in M. galloprovincialis. This signaling cascade should be considered as a possible biomarker of environmental stress and pollution. PMID:19948362

  1. Accelerated Lactate Dehydrogenase Activity Potentiates Osteoclastogenesis via NFATc1 Signaling

    PubMed Central

    Kim, Jin Man; Kwon, So Hyun; Lee, Seoung Hoon; Lee, Soo Young; Jeong, Daewon

    2016-01-01

    Osteoclasts seem to be metabolic active during their differentiation and bone-resorptive activation. However, the functional role of lactate dehydrogenase (LDH), a tetrameric enzyme consisting of an A and/or B subunit that catalyzes interconversion of pyruvate to lactate, in RANKL-induced osteoclast differentiation is not known. In this study, RANKL treatment induced gradual gene expression and activation of the LDH A2B2 isotype during osteoclast differentiation as well as the LDH A1B3 and B4 isotypes during osteoclast maturation after pre-osteoclast formation. Glucose consumption and lactate production in growth media were accelerated during osteoclast differentiation, together with enhanced expression of H+-lactate co-transporter and increased extracellular acidification, demonstrating that glycolytic metabolism was stimulated during differentiation. Further, oxygen consumption via mitochondria was stimulated during osteoclast differentiation. On the contrary, depletion of LDH-A or LDH-B subunit suppressed both glycolytic and mitochondrial metabolism, resulting in reduced mature osteoclast formation via decreased osteoclast precursor fusion and down-regulation of the osteoclastogenic critical transcription factor NFATc1 and its target genes. Collectively, our findings suggest that RANKL-induced LDH activation stimulates glycolytic and mitochondrial respiratory metabolism, facilitating mature osteoclast formation via osteoclast precursor fusion and NFATc1 signaling. PMID:27077737

  2. Aurora A kinase activity influences calcium signaling in kidney cells.

    PubMed

    Plotnikova, Olga V; Pugacheva, Elena N; Golemis, Erica A

    2011-06-13

    Most studies of Aurora A (AurA) describe it as a mitotic centrosomal kinase. However, we and others have recently identified AurA functions as diverse as control of ciliary resorption, cell differentiation, and cell polarity control in interphase cells. In these activities, AurA is transiently activated by noncanonical signals, including Ca(2+)-dependent calmodulin binding. These and other observations suggested that AurA might be involved in pathological conditions, such as polycystic kidney disease (PKD). In this paper, we show that AurA is abundant in normal kidney tissue but is also abnormally expressed and activated in cells lining PKD-associated renal cysts. PKD arises from mutations in the PKD1 or PKD2 genes, encoding polycystins 1 and 2 (PC1 and PC2). AurA binds, phosphorylates, and reduces the activity of PC2, a Ca(2+)-permeable nonselective cation channel and, thus, limits the amplitude of Ca(2+) release from the endoplasmic reticulum. These and other findings suggest AurA may be a relevant new biomarker or target in the therapy of PKD. PMID:21670214

  3. Signal-to-noise ratio in neuro activation PET studies

    SciTech Connect

    Votaw, J.R.

    1996-04-01

    It has become commonplace to compare scanner sensitivity characteristics by comparing noise equivalent count rate curves. However, because a 20-cm diameter uniform phantom is drastically difference from a human brain, these curves give misleading information when planning a neuro activation PET experiment. Signal-to-noise ratio (SNR) calculations have been performed using measured data (Siemens 921 scanner) from the three-dimensional (3-D) Hoffman brain phantom for the purpose of determining the optimal injection and scanning protocol for [{sup 15}O] labeled activation experiments. Region of interest (ROI) values along with the variance due to prompt (trues plus randoms) and random events were determined for various regions and radioactivity concentrations. Calculated attenuation correction was used throughout. Scatter correction was not used when calculating the SNR in activation studies because the number of scattered events is almost identical in each data acquisition and hence cancels. The results indicate that randoms correction should not be performed and that rather than being limited by the scanner capabilities, neuro activation experiments are limited by the amount of radioactivity that can be injected and the length of time the patient can stay in the scanner.

  4. Classification of emotional states from electrocardiogram signals: a non-linear approach based on hurst

    PubMed Central

    2013-01-01

    Background Identifying the emotional state is helpful in applications involving patients with autism and other intellectual disabilities; computer-based training, human computer interaction etc. Electrocardiogram (ECG) signals, being an activity of the autonomous nervous system (ANS), reflect the underlying true emotional state of a person. However, the performance of various methods developed so far lacks accuracy, and more robust methods need to be developed to identify the emotional pattern associated with ECG signals. Methods Emotional ECG data was obtained from sixty participants by inducing the six basic emotional states (happiness, sadness, fear, disgust, surprise and neutral) using audio-visual stimuli. The non-linear feature ‘Hurst’ was computed using Rescaled Range Statistics (RRS) and Finite Variance Scaling (FVS) methods. New Hurst features were proposed by combining the existing RRS and FVS methods with Higher Order Statistics (HOS). The features were then classified using four classifiers – Bayesian Classifier, Regression Tree, K- nearest neighbor and Fuzzy K-nearest neighbor. Seventy percent of the features were used for training and thirty percent for testing the algorithm. Results Analysis of Variance (ANOVA) conveyed that Hurst and the proposed features were statistically significant (p < 0.001). Hurst computed using RRS and FVS methods showed similar classification accuracy. The features obtained by combining FVS and HOS performed better with a maximum accuracy of 92.87% and 76.45% for classifying the six emotional states using random and subject independent validation respectively. Conclusions The results indicate that the combination of non-linear analysis and HOS tend to capture the finer emotional changes that can be seen in healthy ECG data. This work can be further fine tuned to develop a real time system. PMID:23680041

  5. Physiological state gates acquisition and expression of mesolimbic reward prediction signals

    PubMed Central

    Cone, Jackson J.; Fortin, Samantha M.; McHenry, Jenna A.; Stuber, Garret D.; McCutcheon, James E.; Roitman, Mitchell F.

    2016-01-01

    Phasic dopamine signaling participates in associative learning by reinforcing associations between outcomes (unconditioned stimulus; US) and their predictors (conditioned stimulus; CS). However, prior work has always engendered these associations with innately rewarding stimuli. Thus, whether dopamine neurons can acquire prediction signals in the absence of appetitive experience and update them when the value of the outcome changes remains unknown. Here, we used sodium depletion to reversibly manipulate the appetitive value of a hypertonic sodium solution while measuring phasic dopamine signaling in rat nucleus accumbens. Dopamine responses to the NaCl US following sodium depletion updated independent of prior experience. In contrast, prediction signals were only acquired through extensive experience with a US that had positive affective value. Once learned, dopamine prediction signals were flexibly expressed in a state-dependent manner. Our results reveal striking differences with respect to how physiological state shapes dopamine signals evoked by outcomes and their predictors. PMID:26831116

  6. A novel pathway spatiotemporally activates Rac1 and redox signaling in response to fluid shear stress

    PubMed Central

    Liu, Yunhao; Collins, Caitlin; Kiosses, William B.; Murray, Ann M.; Joshi, Monika; Shepherd, Tyson R.; Fuentes, Ernesto J.

    2013-01-01

    Hemodynamic forces regulate embryonic organ development, hematopoiesis, vascular remodeling, and atherogenesis. The mechanosensory stimulus of blood flow initiates a complex network of intracellular pathways, including activation of Rac1 GTPase, establishment of endothelial cell (EC) polarity, and redox signaling. The activity of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase can be modulated by the GTP/GDP state of Rac1; however, the molecular mechanisms of Rac1 activation by flow are poorly understood. Here, we identify a novel polarity complex that directs localized Rac1 activation required for downstream reactive oxygen species (ROS) production. Vav2 is required for Rac1 GTP loading, whereas, surprisingly, Tiam1 functions as an adaptor in a VE-cadherin–p67phox–Par3 polarity complex that directs localized activation of Rac1. Furthermore, loss of Tiam1 led to the disruption of redox signaling both in vitro and in vivo. Our results describe a novel molecular cascade that regulates redox signaling by the coordinated regulation of Rac1 and by linking components of the polarity complex to the NADPH oxidase. PMID:23733346

  7. Stochastic resonance at a subharmonic of a periodic modulation signal in solid-state lasers

    SciTech Connect

    Kravtsov, N V; Lariontsev, E G; Chekina, S N

    2013-10-31

    The stochastic excitation of a subharmonic of a periodic modulation signal in the intensity spectrum of a solid-state laser is experimentally studied upon modulation of the pump rate by the noise and periodic signal. The stochastic resonance (SR) is observed in the presence of bistability in the laser. The conditions for SR at a subharmonic of the periodic modulation signal are determined. (control of laser radiation parameters)

  8. Bisphenol A (BPA) stimulates the interferon signaling and activates the inflammasome activity in myeloid cells.

    PubMed

    Panchanathan, Ravichandran; Liu, Hongzhu; Leung, Yuet-Kin; Ho, Shuk-mei; Choubey, Divaker

    2015-11-01

    Environmental factors contribute to the development of autoimmune diseases, including systemic lupus erythematosus (SLE), which exhibits a strong female bias (female-to-male ratio 9:1). However, the molecular mechanisms remain largely unknown. Because a feedforward loop between the female sex hormone estrogen (E2) and type I interferon (IFN-α/β)-signaling induces the expression of certain p200-family proteins (such as murine p202 and human IFI16) that regulate innate immune responses and modify lupus susceptibility, we investigated whether treatment of myeloid cells with bisphenol A (BPA), an environmental estrogen, could regulate the p200-family proteins and activate innate immune responses. We found that treatment of murine bone marrow-derived cells (BMCs) and human peripheral blood mononuclear cells with BPA induced the expression of ERα and IFN-β, activated the IFN-signaling, and stimulated the expression of the p202 and IFI16 proteins. Further, the treatment increased levels of the NLRP3 inflammasome and stimulated its activity. Accordingly, BPA-treatment of BMCs from non lupus-prone C57BL/6 and the lupus-prone (NZB×NZW)F1 mice activated the type I IFN-signaling, induced the expression of p202, and activated an inflammasome activity. Our study demonstrates that BPA-induced signaling in the murine and human myeloid cells stimulates the type I IFN-signaling that results in an induction of the p202 and IFI16 innate immune sensors for the cytosolic DNA and activates an inflammasome activity. These observations provide novel molecular insights into the role of environmental BPA exposures in potentiating the development of certain autoimmune diseases such as SLE. PMID:26277401

  9. Lipoicmethylenedioxyphenol Reduces Experimental Atherosclerosis through Activation of Nrf2 Signaling

    PubMed Central

    Ying, Zhekang; Chen, Minjie; Xie, Xiaoyun; Wang, Xiaoke; Kherada, Nisharahmed; Desikan, Rajagopal; Mihai, Georgeta; Burns, Patrick; Sun, Qinghua; Rajagopalan, Sanjay

    2016-01-01

    Objective Oxidative stress is implicated in the pathogenesis of atherosclerosis, and Nrf2 is the transcriptional factor central in cellular antioxidant responses. In the present study, we investigate the effect of a dihydrolipoic acid derivative lipoicmethylenedioxyphenol (LMDP) on the progression of atherosclerosis and test whether its effect on atherosclerosis is mediated by Nrf2. Methods and Results Both magnetic resonance imaging (MRI) scanning and en face analysis reveal that 14 weeks of treatment with LMDP markedly reduced atherosclerotic burden in a rabbit balloon vascular injury model. Myograph analyses show decreased aortic contractile response to phenylephrine and increased aortic response to acetylcholine and insulin in LMDP-treated animals, suggesting that LMDP inhibits atherosclerosis through improving vascular function. A role of Nrf2 signaling in mediating the amelioration of vascular function by LMDP was supported by increased Nrf2 translocation into nuclear and increased expression of Nrf2 target genes. Furthermore, chemotaxis analysis with Boydem chamber shows that leukocytes isolated from LMDP-treated rabbits had reduced chemotaxis, and knock-down of Nrf2 significantly reduced the effect of LMDP on the chemotaxis of mouse macrophages. Conclusion Our results support that LMDP has an anti-atherosclerotic effect likely through activation of Nrf2 signaling and subsequent inhibition of macrophage chemotaxis. PMID:26859892

  10. Transmembrane signaling in Saccharomyces cerevisiae as a model for signaling in metazoans: state of the art after 25 years.

    PubMed

    Engelberg, David; Perlman, Riki; Levitzki, Alexander

    2014-12-01

    In the very first article that appeared in Cellular Signalling, published in its inaugural issue in October 1989, we reviewed signal transduction pathways in Saccharomyces cerevisiae. Although this yeast was already a powerful model organism for the study of cellular processes, it was not yet a valuable instrument for the investigation of signaling cascades. In 1989, therefore, we discussed only two pathways, the Ras/cAMP and the mating (Fus3) signaling cascades. The pivotal findings concerning those pathways undoubtedly contributed to the realization that yeast is a relevant model for understanding signal transduction in higher eukaryotes. Consequently, the last 25 years have witnessed the discovery of many signal transduction pathways in S. cerevisiae, including the high osmotic glycerol (Hog1), Stl2/Mpk1 and Smk1 mitogen-activated protein (MAP) kinase pathways, the TOR, AMPK/Snf1, SPS, PLC1 and Pkr/Gcn2 cascades, and systems that sense and respond to various types of stress. For many cascades, orthologous pathways were identified in mammals following their discovery in yeast. Here we review advances in the understanding of signaling in S. cerevisiae over the last 25 years. When all pathways are analyzed together, some prominent themes emerge. First, wiring of signaling cascades may not be identical in all S. cerevisiae strains, but is probably specific to each genetic background. This situation complicates attempts to decipher and generalize these webs of reactions. Secondly, the Ras/cAMP and the TOR cascades are pivotal pathways that affect all processes of the life of the yeast cell, whereas the yeast MAP kinase pathways are not essential. Yeast cells deficient in all MAP kinases proliferate normally. Another theme is the existence of central molecular hubs, either as single proteins (e.g., Msn2/4, Flo11) or as multisubunit complexes (e.g., TORC1/2), which are controlled by numerous pathways and in turn determine the fate of the cell. It is also apparent that

  11. PKCζ regulates Notch receptor routing and activity in a Notch signaling-dependent manner

    PubMed Central

    Sjöqvist, Marika; Antfolk, Daniel; Ferraris, Saima; Rraklli, Vilma; Haga, Cecilia; Antila, Christian; Mutvei, Anders; Imanishi, Susumu Y; Holmberg, Johan; Jin, Shaobo; Eriksson, John E; Lendahl, Urban; Sahlgren, Cecilia

    2014-01-01

    Activation of Notch signaling requires intracellular routing of the receptor, but the mechanisms controlling the distinct steps in the routing process is poorly understood. We identify PKCζ as a key regulator of Notch receptor intracellular routing. When PKCζ was inhibited in the developing chick central nervous system and in cultured myoblasts, Notch-stimulated cells were allowed to undergo differentiation. PKCζ phosphorylates membrane-tethered forms of Notch and regulates two distinct routing steps, depending on the Notch activation state. When Notch is activated, PKCζ promotes re-localization of Notch from late endosomes to the nucleus and enhances production of the Notch intracellular domain, which leads to increased Notch activity. In the non-activated state, PKCζ instead facilitates Notch receptor internalization, accompanied with increased ubiquitylation and interaction with the endosomal sorting protein Hrs. Collectively, these data identify PKCζ as a key regulator of Notch trafficking and demonstrate that distinct steps in intracellular routing are differentially modulated depending on Notch signaling status. PMID:24662486

  12. Active site coupling in PDE:PKA complexes promotes resetting of mammalian cAMP signaling.

    PubMed

    Krishnamurthy, Srinath; Moorthy, Balakrishnan Shenbaga; Xin Xiang, Lim; Xin Shan, Lim; Bharatham, Kavitha; Tulsian, Nikhil Kumar; Mihalek, Ivana; Anand, Ganesh S

    2014-09-16

    Cyclic 3'5' adenosine monophosphate (cAMP)-dependent-protein kinase (PKA) signaling is a fundamental regulatory pathway for mediating cellular responses to hormonal stimuli. The pathway is activated by high-affinity association of cAMP with the regulatory subunit of PKA and signal termination is achieved upon cAMP dissociation from PKA. Although steps in the activation phase are well understood, little is known on how signal termination/resetting occurs. Due to the high affinity of cAMP to PKA (KD ∼ low nM), bound cAMP does not readily dissociate from PKA, thus begging the question of how tightly bound cAMP is released from PKA to reset its signaling state to respond to subsequent stimuli. It has been recently shown that phosphodiesterases (PDEs) can catalyze dissociation of bound cAMP and thereby play an active role in cAMP signal desensitization/termination. This is achieved through direct interactions with the regulatory subunit of PKA, thereby facilitating cAMP dissociation and hydrolysis. In this study, we have mapped direct interactions between a specific cyclic nucleotide phosphodiesterase (PDE8A) and a PKA regulatory subunit (RIα isoform) in mammalian cAMP signaling, by a combination of amide hydrogen/deuterium exchange mass spectrometry, peptide array, and computational docking. The interaction interface of the PDE8A:RIα complex, probed by peptide array and hydrogen/deuterium exchange mass spectrometry, brings together regions spanning the phosphodiesterase active site and cAMP-binding sites of RIα. Computational docking combined with amide hydrogen/deuterium exchange mass spectrometry provided a model for parallel dissociation of bound cAMP from the two tandem cAMP-binding domains of RIα. Active site coupling suggests a role for substrate channeling in the PDE-dependent dissociation and hydrolysis of cAMP bound to PKA. This is the first instance, to our knowledge, of PDEs directly interacting with a cAMP-receptor protein in a mammalian system, and

  13. Activation of the Extracellular Signal-Regulated Kinase Signaling Is Critical for Human Umbilical Cord Mesenchymal Stem Cell Osteogenic Differentiation

    PubMed Central

    Li, Chen-Shuang; Zheng, Zhong; Su, Xiao-Xia; Wang, Fei; Ling, Michelle; Zou, Min; Zhou, Hong

    2016-01-01

    Human umbilical cord mesenchymal stem cells (hUCMSCs) are recognized as candidate progenitor cells for bone regeneration. However, the mechanism of hUCMSC osteogenesis remains unclear. In this study, we revealed that mitogen-activated protein kinases (MAPKs) signaling is involved in hUCMSC osteogenic differentiation in vitro. Particularly, the activation of c-Jun N-terminal kinases (JNK) and p38 signaling pathways maintained a consistent level in hUCMSCs through the entire 21-day osteogenic differentiation period. At the same time, the activation of extracellular signal-regulated kinases (ERK) signaling significantly increased from day 5, peaked at day 9, and declined thereafter. Moreover, gene profiling of osteogenic markers, alkaline phosphatase (ALP) activity measurement, and alizarin red staining demonstrated that the application of U0126, a specific inhibitor for ERK activation, completely prohibited hUCMSC osteogenic differentiation. However, when U0126 was removed from the culture at day 9, ERK activation and osteogenic differentiation of hUCMSCs were partially recovered. Together, these findings demonstrate that the activation of ERK signaling is essential for hUCMSC osteogenic differentiation, which points out the significance of ERK signaling pathway to regulate the osteogenic differentiation of hUCMSCs as an alternative cell source for bone tissue engineering. PMID:26989682

  14. Polyomavirus T Antigens Activate an Antiviral State

    PubMed Central

    Giacobbi, Nicholas S.; Gupta, Tushar; Coxon, Andrew; Pipas, James M.

    2014-01-01

    Ectopic expression of Simian Virus 40 (SV40) large T antigen (LT) in mouse embryonic fibroblasts (MEFs) increased levels of mRNAs encoding interferon stimulated genes (ISGs). The mechanism by which T antigen increases levels of ISGs in MEFs remains unclear. We present evidence that expression of T antigen from SV40, Human Polyomaviruses BK (BKV) or JC (JCV) upregulate production of ISGs in MEFs, and subsequently result in an antiviral state, as determined by inhibition of VSV or EMCV growth. The first 136 amino acids of LT are sufficient for these activities. Furthermore, increased ISG expression and induction of the antiviral state requires STAT1. Finally, the RB binding motif of LT is necessary for activation of STAT1. We conclude that the induction of the STAT1 mediated innate immune response in MEFs is a common feature shared by SV40, BKV and JCV. PMID:25589241

  15. An FGFR1-SPRY2 Signaling Axis Limits Basal Cell Proliferation in the Steady-State Airway Epithelium

    PubMed Central

    Balasooriya, Gayan I.; Johnson, Jo-Anne; Basson, M. Albert; Rawlins, Emma L.

    2016-01-01

    Summary The steady-state airway epithelium has a low rate of stem cell turnover but can nevertheless mount a rapid proliferative response following injury. This suggests a mechanism to restrain proliferation at steady state. One such mechanism has been identified in skeletal muscle in which pro-proliferative FGFR1 signaling is antagonized by SPRY1 to maintain satellite cell quiescence. Surprisingly, we found that deletion of Fgfr1 or Spry2 in basal cells of the adult mouse trachea caused an increase in steady-state proliferation. We show that in airway basal cells, SPRY2 is post-translationally modified in response to FGFR1 signaling. This allows SPRY2 to inhibit intracellular signaling downstream of other receptor tyrosine kinases and restrain basal cell proliferation. An FGFR1-SPRY2 signaling axis has previously been characterized in cell lines in vitro. We now demonstrate an in vivo biological function of this interaction and thus identify an active signaling mechanism that maintains quiescence in the airway epithelium. PMID:27046834

  16. Antithrombotic activities of ferulic acid via intracellular cyclic nucleotide signaling.

    PubMed

    Hong, Qian; Ma, Zeng-Chun; Huang, Hao; Wang, Yu-Guang; Tan, Hong-Ling; Xiao, Cheng-Rong; Liang, Qian-De; Zhang, Han-Ting; Gao, Yue

    2016-04-15

    Ferulic acid (FA) produces protective effects against cardiovascular dysfunctions. However, the mechanisms of FA is still not known. Here we examined the antithrombotic effects of FA and its potential mechanisms. Anticoagulation assays and platelet aggregation was evaluated in vitro and in vivo. Thromboxane B2 (TXB2), cyclic adenosine monophosphate(cAMP), and cyclic guanosine monophosphate (cGMP) was determined using enzyme immunoassay kits. Nitric oxide (NO) production was measured using the Griess reaction. Protein expression was detected by Western blotting analysis. Oral administration of FA prevented death caused by pulmonary thrombosis and prolonged the tail bleeding and clotting time in mice,while, it did not alter the coagulation parameters, including the activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). In addition, FA (50-200µM) dose-dependently inhibited platelet aggregation induced by various platelet agonists, including adenosine diphosphate (ADP), thrombin, collagen, arachidonic acid (AA), and U46619. Further, FA attenuated intracellular Ca(2)(+) mobilization and TXB2 production induced by the platelet agonists. FA increased the levels of cAMP and cGMP and phosphorylated vasodilator-stimulated phosphoprotein (VASP) while decreased phospho-MAPK (mitogen-activated protein kinase) and phosphodiesterase (PDE) in washed rat platelets, VASP is a substrate of cyclic nucleotide and PDE is an enzyme family responsible for hydrolysis of cAMP/cGMP. These results suggest that antithrombotic activities of FA may be regulated by inhibition of platelet aggregation, rather than through inhibiting the release of thromboplastin or formation of thrombin. The mechanism of this action may involve activation of cAMP and cGMP signaling. PMID:26948317

  17. Mesolimbic neuronal activity across behavioral states.

    PubMed

    Woodward, D J; Chang, J Y; Janak, P; Azarov, A; Anstrom, K

    1999-06-29

    A goal of neurophysiology of the mesolimbic system is to determine the activity patterns within the regions in the prefrontal cortex, ventral neostriatum, and amygdala that regulate behavioral patterns to seek rewards. A new technology has been introduced in which arrays of microwires are implanted in different brain regions while activity patterns of ensembles of neurons are recorded for long periods of time during freely moving behaviors. Multichannel instrumentation and software is used for data acquisition and analysis. An initial hypothesis was that neural signals would be encountered in the nucleus accumbens and associated regions specifically related to reward. However, an initial study of neural activity and behavioral patterns during a simple lever press for intravenous cocaine (1 mg/kg) revealed that phasic excitatory or inhibitory neural activity patterns often appear prior to the reward phase. Individual neurons throughout the mesolimbic system appear to code information specific to sensory and motor events, tones, or lever presses in the chain of tasks leading to all rewards so far studied. Different spatial temporal patterns also appear within the same neural populations, as reward is changed from injected cocaine to heroin, from ingested pure water to ethanol in water or sucrose. Overall, patterns of activity for each neuron are found to shift dynamically during the operant task as changes are made in the target reward. Significant shifts in activity of mesolimbic neurons that are unrelated to specific sensory-motor events also appear during complex sessions, such as during a bout of ethanol consumption to reach satiation or during progressive ratio tasks with increasing difficulty. An emerging hypothesis is that some candidate neural elements in the mesolimbic system code the anticipated reward, whereas others serve internal logic functions of motivation that mediate extinction or resumption of specific goal-directed behaviors. PMID:10415645

  18. Quantum minimax receiver for ternary coherent state signal in the presence of thermal noise

    NASA Astrophysics Data System (ADS)

    Kato, Kentaro

    2013-02-01

    This paper is concerned with the minimax strategy in quantum signal detection theory. First we show a numerical calculation method for finding a solution to the quantum minimax decision problem in the case that the average probability of decision errors is used as the quality function of a quantum communication system. To verify the numerical calculation method, ternary coherent state signal is considered in the absence of thermal noise. After that, the error probability of the quantum minimax receiver for the ternary coherent state signal in the pressure of thermal noise is computed by using this numerical calculation method.

  19. Key gravity-sensitive signaling pathways drive T cell activation.

    PubMed

    Boonyaratanakornkit, J B; Cogoli, A; Li, C-F; Schopper, T; Pippia, P; Galleri, G; Meloni, M A; Hughes-Fulford, M

    2005-12-01

    Returning astronauts have experienced altered immune function and increased vulnerability to infection during spaceflights dating back to Apollo and Skylab. Lack of immune response in microgravity occurs at the cellular level. We analyzed differential gene expression to find gravity-dependent genes and pathways. We found inhibited induction of 91 genes in the simulated freefall environment of the random positioning machine. Altered induction of 10 genes regulated by key signaling pathways was verified using real-time RT-PCR. We discovered that impaired induction of early genes regulated primarily by transcription factors NF-kappaB, CREB, ELK, AP-1, and STAT after crosslinking the T-cell receptor contributes to T-cell dysfunction in altered gravity environments. We have previously shown that PKA and PKC are key early regulators in T-cell activation. Since the majority of the genes were regulated by NF-kappaB, CREB, and AP-1, we studied the pathways that regulated these transcription factors. We found that the PKA pathway was down-regulated in vg. In contrast, PI3-K, PKC, and its upstream regulator pLAT were not significantly down-regulated by vectorless gravity. Since NF-kappaB, AP-1, and CREB are all regulated by PKA and are transcription factors predicted by microarray analysis to be involved in the altered gene expression in vectorless gravity, the data suggest that PKA is a key player in the loss of T-cell activation in altered gravity. PMID:16210397

  20. A phenylalanine rotameric switch for signal-state control in bacterial chemoreceptors

    PubMed Central

    Ortega, Davi R.; Yang, Chen; Ames, Peter; Baudry, Jerome; Parkinson, John S.; Zhulin, Igor B.

    2015-01-01

    Bacterial chemoreceptors are widely used as a model system for elucidating the molecular mechanisms of transmembrane signaling and have provided a detailed understanding of how ligand binding by the receptor modulates the activity of its associated kinase CheA. However, the mechanisms by which conformational signals move between signaling elements within a receptor dimer and how they control kinase activity remain unknown. Here, using long molecular dynamics simulations, we show that the kinase-activating cytoplasmic tip of the chemoreceptor fluctuates between two stable conformations in a signal-dependent manner. A highly conserved residue, Phe396, appears to serve as the conformational switch, because flipping of the stacked aromatic rings of an interacting F396-F396' pair in the receptor homodimer takes place concomitantly with the signal-related conformational changes. We suggest that interacting aromatic residues, which are common stabilizers of protein tertiary structure, might serve as rotameric molecular switches in other biological processes as well. PMID:24335957

  1. Astrocyte activation is suppressed in both normal and injured brain by FGF signaling.

    PubMed

    Kang, Wenfei; Balordi, Francesca; Su, Nan; Chen, Lin; Fishell, Gordon; Hébert, Jean M

    2014-07-22

    In the brain, astrocytes are multifunctional cells that react to insults and contain damage. However, excessive or sustained reactive astrocytes can be deleterious to functional recovery or contribute to chronic inflammation and neuronal dysfunction. Therefore, astrocyte activation in response to damage is likely to be tightly regulated. Although factors that activate astrocytes have been identified, whether factors also exist that maintain astrocytes as nonreactive or reestablish their nonreactive state after containing damage remains unclear. By using loss- and gain-of-function genetic approaches, we show that, in the unperturbed adult neocortex, FGF signaling is required in astrocytes to maintain their nonreactive state. Similarly, after injury, FGF signaling delays the response of astrocytes and accelerates their deactivation. In addition, disrupting astrocytic FGF receptors results in reduced scar size without affecting neuronal survival. Overall, this study reveals that the activation of astrocytes in the normal and injured neocortex is not only regulated by proinflammatory factors, but also by factors such as FGFs that suppress activation, providing alternative therapeutic targets. PMID:25002516

  2. Astrocyte activation is suppressed in both normal and injured brain by FGF signaling

    PubMed Central

    Kang, Wenfei; Balordi, Francesca; Su, Nan; Chen, Lin; Fishell, Gordon; Hébert, Jean M.

    2014-01-01

    In the brain, astrocytes are multifunctional cells that react to insults and contain damage. However, excessive or sustained reactive astrocytes can be deleterious to functional recovery or contribute to chronic inflammation and neuronal dysfunction. Therefore, astrocyte activation in response to damage is likely to be tightly regulated. Although factors that activate astrocytes have been identified, whether factors also exist that maintain astrocytes as nonreactive or reestablish their nonreactive state after containing damage remains unclear. By using loss- and gain-of-function genetic approaches, we show that, in the unperturbed adult neocortex, FGF signaling is required in astrocytes to maintain their nonreactive state. Similarly, after injury, FGF signaling delays the response of astrocytes and accelerates their deactivation. In addition, disrupting astrocytic FGF receptors results in reduced scar size without affecting neuronal survival. Overall, this study reveals that the activation of astrocytes in the normal and injured neocortex is not only regulated by proinflammatory factors, but also by factors such as FGFs that suppress activation, providing alternative therapeutic targets. PMID:25002516

  3. The role of protease-activated receptor type 2 in nociceptive signaling and pain.

    PubMed

    Mrozkova, P; Palecek, J; Spicarova, D

    2016-07-18

    Protease-activated receptors (PARs) belong to the G-protein-coupled receptor family, that are expressed in many body tissues especially in different epithelial cells, mast cells and also in neurons and astrocytes. PARs play different physiological roles according to the location of their expression. Increased evidence supports the importance of PARs activation during nociceptive signaling and in the development of chronic pain states. This short review focuses on the role of PAR2 receptors in nociceptive transmission with the emphasis on the modulation at the spinal cord level. PAR2 are cleaved and subsequently activated by endogenous proteases such as tryptase and trypsin. In vivo, peripheral and intrathecal administration of PAR2 agonists induces thermal and mechanical hypersensitivity that is thought to be mediated by PAR2-induced release of pronociceptive neuropeptides and modulation of different receptors. PAR2 activation leads also to sensitization of transient receptor potential channels (TRP) that are crucial for nociceptive signaling and modulation. PAR2 receptors may play an important modulatory role in the development and maintenance of different pathological pain states and could represent a potential target for new analgesic treatments. PMID:27070742

  4. Deriving stellar inclination of slow rotators using stellar activity signal

    NASA Astrophysics Data System (ADS)

    Dumusque, Xavier

    2015-01-01

    Stellar inclination is an important parameter for many astrophysical studies. In the context of exoplanets, this allows us to derive the true obliquity of a system if the projected stellar spin-planetary orbit angle can measured via the Rossiter-Mclaughlin effect. Although different techniques allow us to estimate stellar inclination for fast rotators, it becomes much more difficult when stars are rotating slower than 2-2.5 km.s-1. By using the new activity simulation SOAP 2.0 that can reproduce the photometric and spectroscopic variations induced by stellar activity, we are able to fit the activity variation of solar-type stars and derive their inclination. The case of the equator-on star HD189733 will be presented, as well as the case of Alpha Centauri B, which present an inclination of 45+9-19 degrees, implying that the earth-mass orbiting planet is not transiting if aligned with its host star. Other exemples will also demonstrate the power of the technique, that can infer a stellar inclination, even for slow rotators like Alpha Centauri B, that present a projected rotational velocity smaller than 1.15 km.s-1. In addition, the SOAP 2.0 simulation can be used to correct for the effect of activity when one major active region is dominating the RV signal. This could enhance the detection of small mass exoplanets orbiting slightly active stars.This project is funded by ETAEARTH (European Union Seventh Framework Programme (FP7/2007-2013) under Grant Agreement n. 313014), a transnational collaboration between European countries and the US (the Swiss Space Office, the Harvard Origin of Life Initiative, the Scottish Universities Physics Alliance, the University of Geneva, the Smithsonian Astrophysical Observatory, the Italian National Astrophysical Institute, the University of St. Andrews, Queens University Belfast, and the University of Edinburgh) setup to optimize the synergy between space-and ground-based data whose scientific potential for the characterization of

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  6. Hypoxia promotes drug resistance in osteosarcoma cells via activating AMP-activated protein kinase (AMPK) signaling

    PubMed Central

    Zhao, Changfu; Zhang, Qiao; Yu, Tao; Sun, Shudong; Wang, Wenjun; Liu, Guangyao

    2016-01-01

    Purpose Drug resistance has been recognized to be a major obstacle to the chemotherapy for osteosarcoma. And the potential importance of hypoxia as a target to reverse drug resistance in osteosarcoma has been indicated, though the mechanism underlining such role is not clarified. The present study aims to investigate the role of hypoxia in the drug resistance in osteosarcoma cells via activating AMP-activated protein kinase (AMPK) signaling. Experimental design We investigated the promotion of the resistance to doxorubicin of osteosarcoma MG-63 and U2-os cells in vitro, and then determined the role of hypoxia-inducible factor-1 (HIF-1)α and HIF-1β, the activation and regulatory role of AMPK in the osteosarcoma U2-os cells which were treated with doxorubicin under hypoxia. Results It was demonstrated that hypoxia significantly reduced the sensitivity of MG-63 and U2-os cells to doxorubicin, indicating an inhibited viability reduction and a reduced apoptosis promotion. And such reduced sensitivity was not associated with HIF-1α, though it was promoted by hypoxia in U2-os cells. Interestingly, the AMPK signaling was significantly promoted by hypoxia in the doxorubicin-treated U2-os cells, with a marked upregulation of phosphorylated AMPK (Thr 172) and phosphorylated acetyl-CoA carboxylase (ACC) (Ser 79), which were sensitive to the AMPK activator, AICAR and the AMPK inhibitor, Compound C. Moreover, the promoted AMPK activity by AICAR or the downregulated AMPK activity by Compound C significantly reduced or promoted the sensitivity of U2-os cells to doxorubicin. Conclusion The present study confirmed the AMPK signaling activation in the doxorubicin-treated osteosarcoma cells, in response to hypoxia, and the chemical upregulation or downregulation of AMPK signaling reduced or increased the chemo-sensitivity of osteosarcoma U2-os cells in vitro. Our study implies that AMPK inhibition might be a effective strategy to sensitize osteocarcoma cells to chemotherapy. PMID

  7. An MENC Bicentennial Commission Report on State Activities

    ERIC Educational Resources Information Center

    Music Educators Journal, 1976

    1976-01-01

    The MENC Bicentennial Commission requested each state chairman to submit a list of projects that were representative of the activities in that state. Included here are 27 states and the music activities appropriate for the Bicentennial year. (Editor/RK)

  8. Premature senescence involving p53 and p16 is activated in response to constitutive MEK/MAPK mitogenic signaling

    PubMed Central

    Lin, Athena W.; Barradas, Marta; Stone, James C.; van Aelst, Linda; Serrano, Manuel; Lowe, Scott W.

    1998-01-01

    Oncogenic Ras transforms immortal rodent cells to a tumorigenic state, in part, by constitutively transmitting mitogenic signals through the mitogen-activated protein kinase (MAPK) cascade. In primary cells, Ras is initially mitogenic but eventually induces premature senescence involving the p53 and p16INK4a tumor suppressors. Constitutive activation of MEK (a component of the MAPK cascade) induces both p53 and p16, and is required for Ras-induced senescence of normal human fibroblasts. Furthermore, activated MEK permanently arrests primary murine fibroblasts but forces uncontrolled mitogenesis and transformation in cells lacking either p53 or INK4a. The precisely opposite response of normal and immortalized cells to constitutive activation of the MAPK cascade implies that premature senescence acts as a fail-safe mechanism to limit the transforming potential of excessive Ras mitogenic signaling. Consequently, constitutive MAPK signaling activates p53 and p16 as tumor suppressors. PMID:9765203

  9. Biomechanical Signals Inhibit IKK Activity to Attenuate NF-κB Transcription Activity in Inflamed Chondrocytes

    PubMed Central

    Dossumbekova, Anar; Anghelina, Mirela; Madhavan, Shashi; He, Lingli; Quan, Ning; Knobloch, Thomas; Agarwal, Sudha

    2016-01-01

    Objective While the effects of biomechanical signals in the form of joint movement and exercise are known to be beneficial to inflamed joints, limited information is available regarding the intracellular mechanisms of their actions. This study was undertaken to examine the intracellular mechanisms by which biomechanical signals suppress proinflammatory gene induction by the interleukin-1-β (IL-1β)–induced NF-κB signaling cascade in articular chondrocytes. Methods Primary rat articular chondrocytes were exposed to biomechanical signals in the form of cyclic tensile strain, and the effects on the NF-κB signaling cascade were examined by Western blot analysis, real-time polymerase chain reaction, and immunofluorescence. Results Cyclic tensile strain rapidly inhibited the IL-1β–induced nuclear translocation of NF-κB, but not its IL-1β–induced phosphorylation at serine 276 and serine 536, which are necessary for its transactivation and transcriptional efficacy, respectively. Examination of upstream events revealed that cyclic tensile strain also inhibited the cytoplasmic protein degradation of IκBβ and IκBα, as well as repressed their gene transcription. Additionally, cyclic tensile strain induced a rapid nuclear translocation of IκBα to potentially prevent NF-κB binding to DNA. Furthermore, the inhibition of IL-1β–induced degradation of IκB by cyclic tensile strain was mediated by down-regulation of IκB kinase activity. Conclusion These results indicate that the signals generated by cyclic tensile strain act at multiple sites within the NF-κB signaling cascade to inhibit IL-1β–induced proinflammatory gene induction. Taken together, these findings provide insight into how biomechanical signals regulate and reduce inflammation, and underscore their potential in enhancing the ability of chondrocytes to curb inflammation in diseased joints. PMID:17907174

  10. Resistance of Cancer Cells to Targeted Therapies Through the Activation of Compensating Signaling Loops.

    PubMed

    von Manstein, Viktoria; Yang, Chul Min; Richter, Diane; Delis, Natalia; Vafaizadeh, Vida; Groner, Bernd

    2013-12-01

    The emergence of low molecular weight kinase inhibitors as "targeted" drugs has led to remarkable advances in the treatment of cancer patients. The clinical benefits of these tumor therapies, however, vary widely in patient populations and with duration of treatment. Intrinsic and acquired resistance against such drugs limits their efficacy. In addition to the well studied mechanisms of resistance based upon drug transport and metabolism, genetic alterations in drug target structures and the activation of compensatory cell signaling have received recent attention. Adaptive responses can be triggered which counteract the initial dependence of tumor cells upon a particular signaling molecule and allow only a transient inhibition of tumor cell growth. These compensating signaling mechanisms are often based upon the relief of repression of regulatory feedback loops. They might involve cell autonomous, intracellular events or they can be mediated via the secretion of growth factor receptor ligands into the tumor microenvironment and signal induction in an auto- or paracrine fashion. The transcription factors Stat3 and Stat5 mediate the biological functions of cytokines, interleukins and growth factors and can be considered as endpoints of multiple signaling pathways. In normal cells this activation is transient and the Stat molecules return to their non-phosphorylated state within a short time period. In tumor cells the balance between activating and de-activating signals is disturbed resulting in the persistent activation of Stat3 or Stat5. The constant activation of Stat3 induces the expression of target genes, which cause the proliferation and survival of cancer cells, as well as their migration and invasive behavior. Activating components of the Jak-Stat pathway have been recognized as potentially valuable drug targets and important principles of compensatory signaling circuit induction during targeted drug treatment have been discovered in the context of kinase

  11. Signal transducer and activator of transcription 3 limits Epstein-Barr virus lytic activation in B lymphocytes.

    PubMed

    Hill, Erik R; Koganti, Siva; Zhi, Jizu; Megyola, Cynthia; Freeman, Alexandra F; Palendira, Umaimainthan; Tangye, Stuart G; Farrell, Paul J; Bhaduri-McIntosh, Sumita

    2013-11-01

    Lytic activation of Epstein-Barr virus (EBV) is central to its life cycle and to most EBV-related diseases. However, not every EBV-infected B cell is susceptible to lytic activation. This lack of uniform susceptibility to lytic activation also directly impacts the success of viral oncolytic therapy for EBV cancers, yet determinants of susceptibility to lytic induction signals are not well understood. To determine if host factors influence susceptibility to EBV lytic activation, we developed a technique to separate lytic from refractory cells and reported that EBV lytic activation occurs preferentially in cells with lower levels of signal transducer and activator of transcription 3 (STAT3). Using this tool to detect single cells, we now extend the correlation between STAT3 and lytic versus refractory states to EBV-infected circulating B cells in patients with primary EBV infection, leading us to investigate whether STAT3 controls susceptibility to EBV lytic activation. In loss-of-function and gain-of-function studies in EBV-positive B lymphoma and lymphoblastoid cells, we found that the levels of functional STAT3 regulate susceptibility to EBV lytic activation. This prompted us to identify a pool of candidate cellular genes that might be regulated by STAT3 to limit EBV lytic activation. From this pool, we confirmed increases in transcript levels in refractory cells of a set of genes known to participate in transcription repression. Taken together, our findings place STAT3 at a critical crossroads between EBV latency and lytic activation, processes fundamental to EBV lymphomagenesis. PMID:23966384

  12. Crystal structure of the GTPase domain and the bundle signalling element of dynamin in the GDP state.

    PubMed

    Anand, Roopsee; Eschenburg, Susanne; Reubold, Thomas F

    2016-01-01

    Dynamin is the prototype of a family of large multi-domain GTPases. The 100 kDa protein is a key player in clathrin-mediated endocytosis, where it cleaves off vesicles from membranes using the energy from GTP hydrolysis. We have solved the high resolution crystal structure of a fusion protein of the GTPase domain and the bundle signalling element (BSE) of dynamin 1 liganded with GDP. The structure provides a hitherto missing snapshot of the GDP state of the hydrolytic cycle of dynamin and reveals how the switch I region moves away from the active site after GTP hydrolysis and release of inorganic phosphate. Comparing our structure of the GDP state with the known structures of the GTP state, the transition state and the nucleotide-free state of dynamin 1 we describe the structural changes through the hydrolytic cycle. PMID:26612256

  13. Allosteric Activation of the RNF146 Ubiquitin Ligase by a Poly(ADP-ribosyl)ation Signal

    PubMed Central

    DaRosa, Paul A.; Wang, Zhizhi; Jiang, Xiaomo; Pruneda, Jonathan N.; Cong, Feng; Klevit, Rachel E.; Xu, Wenqing

    2014-01-01

    Protein poly(ADP-ribosyl)ation (PARylation) plays a role in diverse cellular processes such as DNA repair, transcription, Wnt signaling, and cell death1–6. Recent studies have shown that PARylation can serve as a signal for the polyubiquitination and degradation of several critical regulatory proteins, including Axin and 3BP2 (refs 7–9). The RING-type E3 ubiquitin ligase RNF146 (a.k.a. Iduna) is responsible for PARylation-dependent ubiquitination (PARdU)10–12. Here we provide a structural basis for RNF146 catalyzed PARdU and how PARdU specificity is achieved. First, we show that iso-ADPr, the smallest internal poly(ADP-ribose) (PAR) structural unit, binds between the WWE and RING domains of RNF146 and functions as an allosteric signal that switches the RING domain from a catalytically inactive state to an active one. In the absence of PAR, the RING domain is unable to efficiently bind and activate an E2. Binding of PAR/iso-ADPr induces a major conformational change that creates a functional RING structure. Thus RNF146 represents a new mechanistic class of RING E3 ligases whose activities are regulated by non-covalent ligand binding, which may provide a template for designing inducible protein-degradation systems. Second, we found that RNF146 directly interacts with the PAR polymerase tankyrase (TNKS). Disruption of the RNF146/TNKS interaction inhibits turnover of the substrate Axin in cells. Thus, both substrate PARylation and PARdU are catalyzed by enzymes within the same protein complex, and PARdU substrate specificity may be primarily determined by the substrate-TNKS interaction. We propose that maintenance of unliganded RNF146 in an inactive state may serve to maintain the stability of the RNF146-TNKS complex, which in turn regulates the homeostasis of PARdU activity in the cell. PMID:25327252

  14. Cortical energy demands of signaling and nonsignaling components in brain are conserved across mammalian species and activity levels

    PubMed Central

    Hyder, Fahmeed; Rothman, Douglas L.; Bennett, Maxwell R.

    2013-01-01

    The continuous need for ion gradient restoration across the cell membrane, a prerequisite for synaptic transmission and conduction, is believed to be a major factor for brain’s high oxidative demand. However, do energy requirements of signaling and nonsignaling components of cortical neurons and astrocytes vary with activity levels and across species? We derived oxidative ATP demand associated with signaling (Ps) and nonsignaling (Pns) components in the cerebral cortex using species-specific physiologic and anatomic data. In rat, we calculated glucose oxidation rates from layer-specific neuronal activity measured across different states, spanning from isoelectricity to awake and sensory stimulation. We then compared these calculated glucose oxidation rates with measured glucose metabolic data for the same states as reported by 2-deoxy-glucose autoradiography. Fixed values for Ps and Pns were able to predict the entire range of states in the rat. We then calculated glucose oxidation rates from human EEG data acquired under various conditions using fixed Ps and Pns values derived for the rat. These calculated metabolic data in human cerebral cortex compared well with glucose metabolism measured by PET. Independent of species, linear relationship was established between neuronal activity and neuronal oxidative demand beyond isoelectricity. Cortical signaling requirements dominated energy demand in the awake state, whereas nonsignaling requirements were ∼20% of awake value. These predictions are supported by 13C magnetic resonance spectroscopy results. We conclude that mitochondrial energy support for signaling and nonsignaling components in cerebral cortex are conserved across activity levels in mammalian species. PMID:23319606

  15. Edge states in confined active fluids

    NASA Astrophysics Data System (ADS)

    Souslov, Anton; Vitelli, Vincenzo

    Recently, topologically protected edge modes have been proposed and realized in both mechanical and acoustic metamaterials. In one class of such metamaterials, Time-Reversal Symmetry is broken, and, to achieve this TRS breaking in mechanical and acoustic systems, an external energy input must be used. For example, motors provide a driving force that uses energy and, thus, explicitly break TRS. As a result, motors have been used as an essential component in the design of topological metamaterials. By contrast, we explore the design of topological metamaterials that use a class of far-from-equilibrium liquids, called polar active liquids, that spontaneously break TRS. We thus envision the confinement of a polar active liquid to a prescribed geometry in order to realize topological order with broken time-reversal symmetry. We address the design of the requisite geometries, for example a regular honeycomb lattice composed of annular channels, in which the active liquid may be confined. We also consider the physical character of the active liquid that, when introduced into the prescribed geometry, will spontaneously form the flow pattern of a metamaterial with topologically protected edge states. Finally, we comment on potential experimental realizations of such metamaterials.

  16. Signal Activation and Inactivation by the Gα Helical Domain: A Long-Neglected Partner in G Protein Signaling

    PubMed Central

    Dohlman, Henrik G.; Jones, Janice C.

    2013-01-01

    Heterotrimeric guanine nucleotide–binding proteins (G proteins) are positioned at the top of many signal transduction pathways. The G protein α subunit is composed of two domains, one that resembles Ras and another that is composed entirely of α helices. Historically, most attention has focused on the Ras-like domain, but emerging evidence reveals that the helical domain is an active participant in G protein signaling. PMID:22649098

  17. CD28 costimulatory signals in T lymphocyte activation: Emerging functions beyond a qualitative and quantitative support to TCR signalling.

    PubMed

    Porciello, Nicla; Tuosto, Loretta

    2016-04-01

    CD28 is one of the most important co-stimulatory receptors necessary for full T lymphocyte activation. By binding its cognate ligands, B7.1/CD80 or B7.2/CD86, expressed on the surface of professional antigen presenting cells (APC), CD28 initiates several signalling cascades, which qualitatively and quantitatively support T cell receptor (TCR) signalling. More recent data evidenced that human CD28 can also act as a TCR-independent signalling unit, by delivering specific signals, which regulate the expression of pro-inflammatory cytokine/chemokines. Despite the enormous progresses made in identifying the mechanisms and molecules involved in CD28 signalling properties, much remains to be elucidated, especially in the light of the functional differences observed between human and mouse CD28. In this review we provide an overview of the current mechanisms and molecules through which CD28 support TCR signalling and highlight recent findings on the specific signalling motifs that regulate the unique pro-inflammatory activity of human CD28. PMID:26970725

  18. Akt1 signaling coordinates BMP signaling and β-catenin activity to regulate second heart field progenitor development.

    PubMed

    Luo, Wen; Zhao, Xia; Jin, Hengwei; Tao, Lichan; Zhu, Jingai; Wang, Huijuan; Hemmings, Brian A; Yang, Zhongzhou

    2015-02-15

    Second heart field (SHF) progenitors exhibit continued proliferation and delayed differentiation, which are modulated by FGF4/8/10, BMP and canonical Wnt/β-catenin signaling. PTEN-Akt signaling regulates the stem cell/progenitor cell homeostasis in several systems, such as hematopoietic stem cells, intestinal stem cells and neural progenitor cells. To address whether PTEN-Akt signaling is involved in regulating cardiac progenitors, we deleted Pten in SHF progenitors. Deletion of Pten caused SHF expansion and increased the size of the SHF derivatives, the right ventricle and the outflow tract. Cell proliferation of cardiac progenitors was enhanced, whereas cardiac differentiation was unaffected by Pten deletion. Removal of Akt1 rescued the phenotype and early lethality of Pten deletion mice, suggesting that Akt1 was the key downstream target that was negatively regulated by PTEN in cardiac progenitors. Furthermore, we found that inhibition of FOXO by Akt1 suppressed the expression of the gene encoding the BMP ligand (BMP7), leading to dampened BMP signaling in the hearts of Pten deletion mice. Cardiac activation of Akt also increased the Ser552 phosphorylation of β-catenin, thus enhancing its activity. Reducing β-catenin levels could partially rescue heart defects of Pten deletion mice. We conclude that Akt signaling regulates the cell proliferation of SHF progenitors through coordination of BMP signaling and β-catenin activity. PMID:25670795

  19. Improvement of EEG Signal Acquisition: An Electrical Aspect for State of the Art of Front End

    PubMed Central

    Usakli, Ali Bulent

    2010-01-01

    The aim of this study is to present some practical state-of-the-art considerations in acquiring satisfactory signals for electroencephalographic signal acquisition. These considerations are important for users and system designers. Especially choosing correct electrode and design strategy of the initial electronic circuitry front end plays an important role in improving the system's measurement performance. Considering the pitfalls in the design of biopotential measurement system and recording session conditions creates better accuracy. In electroencephalogram (EEG) recording electrodes, system electronics including filtering, amplifying, signal conversion, data storing, and environmental conditions affect the recording performance. In this paper, EEG electrode principles and main points of electronic noise reduction methods in EEG signal acquisition front end are discussed, and some suggestions for improving signal acquisition are presented. PMID:20148074

  20. Optimal quantum state estimation with use of the no-signaling principle

    SciTech Connect

    Han, Yeong-Deok; Bae, Joonwoo; Wang Xiangbin; Hwang, Won-Young

    2010-12-15

    A simple derivation of the optimal state estimation of a quantum bit was obtained by using the no-signaling principle. In particular, the no-signaling principle determines a unique form of the guessing probability independent of figures of merit, such as the fidelity or information gain. This proves that the optimal estimation for a quantum bit can be achieved by the same measurement for almost all figures of merit.

  1. On-line, adaptive state estimator for active noise control

    NASA Technical Reports Server (NTRS)

    Lim, Tae W.

    1994-01-01

    Dynamic characteristics of airframe structures are expected to vary as aircraft flight conditions change. Accurate knowledge of the changing dynamic characteristics is crucial to enhancing the performance of the active noise control system using feedback control. This research investigates the development of an adaptive, on-line state estimator using a neural network concept to conduct active noise control. In this research, an algorithm has been developed that can be used to estimate displacement and velocity responses at any locations on the structure from a limited number of acceleration measurements and input force information. The algorithm employs band-pass filters to extract from the measurement signal the frequency contents corresponding to a desired mode. The filtered signal is then used to train a neural network which consists of a linear neuron with three weights. The structure of the neural network is designed as simple as possible to increase the sampling frequency as much as possible. The weights obtained through neural network training are then used to construct the transfer function of a mode in z-domain and to identify modal properties of each mode. By using the identified transfer function and interpolating the mode shape obtained at sensor locations, the displacement and velocity responses are estimated with reasonable accuracy at any locations on the structure. The accuracy of the response estimates depends on the number of modes incorporated in the estimates and the number of sensors employed to conduct mode shape interpolation. Computer simulation demonstrates that the algorithm is capable of adapting to the varying dynamic characteristics of structural properties. Experimental implementation of the algorithm on a DSP (digital signal processing) board for a plate structure is underway. The algorithm is expected to reach the sampling frequency range of about 10 kHz to 20 kHz which needs to be maintained for a typical active noise control

  2. Unfolding the relationship between secreted molecular chaperones and macrophage activation states

    PubMed Central

    Henderson, Samantha

    2008-01-01

    Over the last 20 years, it has emerged that many molecular chaperones and protein-folding catalysts are secreted from cells and function, somewhat in the manner of cytokines, as pleiotropic signals for a variety of cells, with much attention being focused on the macrophage. During the last decade, it has become clear that macrophages respond to bacterial, protozoal, parasitic and host signals to generate phenotypically distinct states of activation. These activation states have been termed ‘classical’ and ‘alternative’ and represent not a simple bifurcation in response to external signals but a range of cellular phenotypes. From an examination of the literature, the hypothesis is propounded that mammalian molecular chaperones are able to induce a wide variety of alternative macrophage activation states, and this may be a system for relating cellular or tissue stress to appropriate macrophage responses to restore homeostatic equilibrium. PMID:18958583

  3. Dermatophytes Activate Skin Keratinocytes via Mitogen-Activated Protein Kinase Signaling and Induce Immune Responses

    PubMed Central

    Achterman, Rebecca R.; Moyes, David L.; Thavaraj, Selvam; Smith, Adam R.; Blair, Kris M.

    2015-01-01

    Dermatophytes cause superficial and cutaneous fungal infections in immunocompetent hosts and invasive disease in immunocompromised hosts. However, the host mechanisms that regulate innate immune responses against these fungi are largely unknown. Here, we utilized commercially available epidermal tissues and primary keratinocytes to assess (i) damage induction by anthropophilic, geophilic, and zoophilic dermatophyte strains and (ii) the keratinocyte signaling pathways, transcription factors, and proinflammatory responses induced by a representative dermatophyte, Trichophyton equinum. Initially, five dermatophyte species were tested for their ability to invade, cause tissue damage, and induce cytokines, with Microsporum gypseum inducing the greatest level of damage and cytokine release. Using T. equinum as a representative dermatophyte, we found that the mitogen-activated protein kinase (MAPK) pathways were predominantly affected, with increased levels of phospho-p38 and phospho-Jun N-terminal protein kinase (JNK) but decreased levels of phospho-extracellular signal-regulated kinases 1 and 2 (ERK1/2). Notably, the NF-κB and PI3K pathways were largely unaffected. T. equinum also significantly increased expression of the AP-1-associated transcription factor, c-Fos, and the MAPK regulatory phosphatase, MKP1. Importantly, the ability of T. equinum to invade, cause tissue damage, activate signaling and transcription factors, and induce proinflammatory responses correlated with germination, indicating that germination may be important for dermatophyte virulence and host immune activation. PMID:25667269

  4. Episodes of Ionospheric Disturbances caused by Solar Activity probed using Long Wave Terrestrial Radio Signals

    NASA Astrophysics Data System (ADS)

    Shanmugha Sundaram, GA; Shaik, Manoj

    2016-07-01

    The dynamic spectral record of long wave (LW) radio signals (kHz band) had registered a disturbed condition of the ionosphere region involved with propagation of these signals. The reason for such signatures in the dynamic spectrogram can be accredited to the impact of Solar Energetic Particles (SEP) on the ionosphere along the propagation path of terrestrial long wave radiation, studied using the Multi-Hop propagation model. Points of reflection in the ionosphere directly above specific locations above the Earth where determined. Total Electron Content (TEC) values for such regions were obtained from interpretation of the global positioning system (GPS) data. From a comparisons of such results during periods when the Sun was quiet and active, the magnitude of ionosphere disturbance contributed by the various active solar phenomenae has been determined. The work reported here is based on the impact of Geomagnetic storm (K_{p}=6) on the TEC, that occurred on 16 April 2015. LW radio signals from transmitter locations operated by the United States Navy near Lualualei, Hawaii (Geomagnetic lat 21°25'13.38"}N, Geomagnetic long 158°09'14.35"W) and by France at Rosnay (Geomagnetic lat 46°42'47"N, Geomagnetic long 1°14'39"E) were monitored closely to know the extent of ionospheric impact.

  5. Abnormal Activation of BMP Signaling Causes Myopathy in Fbn2 Null Mice.

    PubMed

    Sengle, Gerhard; Carlberg, Valerie; Tufa, Sara F; Charbonneau, Noe L; Smaldone, Silvia; Carlson, Eric J; Ramirez, Francesco; Keene, Douglas R; Sakai, Lynn Y

    2015-06-01

    Fibrillins are large extracellular macromolecules that polymerize to form the backbone structure of connective tissue microfibrils. Mutations in the gene for fibrillin-1 cause the Marfan syndrome, while mutations in the gene for fibrillin-2 cause Congenital Contractural Arachnodactyly. Both are autosomal dominant disorders, and both disorders affect musculoskeletal tissues. Here we show that Fbn2 null mice (on a 129/Sv background) are born with reduced muscle mass, abnormal muscle histology, and signs of activated BMP signaling in skeletal muscle. A delay in Myosin Heavy Chain 8, a perinatal myosin, was found in Fbn2 null forelimb muscle tissue, consistent with the notion that muscle defects underlie forelimb contractures in these mice. In addition, white fat accumulated in the forelimbs during the early postnatal period. Adult Fbn2 null mice are already known to demonstrate persistent muscle weakness. Here we measured elevated creatine kinase levels in adult Fbn2 null mice, indicating ongoing cycles of muscle injury. On a C57Bl/6 background, Fbn2 null mice showed severe defects in musculature, leading to neonatal death from respiratory failure. These new findings demonstrate that loss of fibrillin-2 results in phenotypes similar to those found in congenital muscular dystrophies and that FBN2 should be considered as a candidate gene for recessive congenital muscular dystrophy. Both in vivo and in vitro evidence associated muscle abnormalities and accumulation of white fat in Fbn2 null mice with abnormally activated BMP signaling. Genetic rescue of reduced muscle mass and accumulation of white fat in Fbn2 null mice was accomplished by deleting a single allele of Bmp7. In contrast to other reports that activated BMP signaling leads to muscle hypertrophy, our findings demonstrate the exquisite sensitivity of BMP signaling to the fibrillin-2 extracellular environment during early postnatal muscle development. New evidence presented here suggests that fibrillin-2 can

  6. Sunitinib activates Axl signaling in renal cell cancer.

    PubMed

    van der Mijn, Johannes C; Broxterman, Henk J; Knol, Jaco C; Piersma, Sander R; De Haas, Richard R; Dekker, Henk; Pham, Thang V; Van Beusechem, Victor W; Halmos, Balazs; Mier, James W; Jiménez, Connie R; Verheul, Henk M W

    2016-06-15

    Mass spectrometry-based phosphoproteomics provides a unique unbiased approach to evaluate signaling network in cancer cells. The tyrosine kinase inhibitor sunitinib is registered as treatment for patients with renal cell cancer (RCC). We investigated the effect of sunitinib on tyrosine phosphorylation in RCC tumor cells to get more insight in its mechanism of action and thereby to find potential leads for combination treatment strategies. Sunitinib inhibitory concentrations of proliferation (IC50) of 786-O, 769-p and A498 RCC cells were determined by MTT-assays. Global tyrosine phosphorylation was measured by LC-MS/MS after immunoprecipitation with the antiphosphotyrosine antibody p-TYR-100. Phosphoproteomic profiling of 786-O cells yielded 1519 phosphopeptides, corresponding to 675 unique proteins including 57 different phosphorylated protein kinases. Compared to control, incubation with sunitinib at its IC50 of 2 µM resulted in downregulation of 86 phosphopeptides including CDK5, DYRK3, DYRK4, G6PD, PKM and LDH-A, while 94 phosphopeptides including Axl, FAK, EPHA2 and p38α were upregulated. Axl- (y702), FAK- (y576) and p38α (y182) upregulation was confirmed by Western Blot in 786-O and A498 cells. Subsequent proliferation assays revealed that inhibition of Axl with a small molecule inhibitor (R428) sensitized 786-O RCC cells and immortalized endothelial cells to sunitinib up to 3 fold. In conclusion, incubation with sunitinib of RCC cells causes significant upregulation of multiple phosphopeptides including Axl. Simultaneous inhibition of Axl improves the antitumor activity of sunitinib. We envision that evaluation of phosphoproteomic changes by TKI treatment enables identification of new targets for combination treatment strategies. PMID:26815723

  7. Signal integration by Ca(2+) regulates intestinal stem-cell activity.

    PubMed

    Deng, Hansong; Gerencser, Akos A; Jasper, Heinrich

    2015-12-10

    Somatic stem cells maintain tissue homeostasis by dynamically adjusting proliferation and differentiation in response to stress and metabolic cues. Here we identify Ca(2+) signalling as a central regulator of intestinal stem cell (ISC) activity in Drosophila. We show that dietary L-glutamate stimulates ISC division and gut growth. The metabotropic glutamate receptor (mGluR) is required in ISCs for this response, and for an associated modulation of cytosolic Ca(2+) oscillations that results in sustained high cytosolic Ca(2+) concentrations. High cytosolic Ca(2+) concentrations induce ISC proliferation by regulating Calcineurin and CREB-regulated transcriptional co-activator (Crtc). In response to a wide range of dietary and stress stimuli, ISCs reversibly transition between Ca(2+) oscillation states that represent poised or activated modes of proliferation, respectively. We propose that the dynamic regulation of intracellular Ca(2+) levels allows effective integration of diverse mitogenic signals in ISCs to adapt their proliferative activity to the needs of the tissue. PMID:26633624

  8. Suppressing background signals in solid state NMR via the Electronic Mixing-Mediated Annihilation (EMMA) method

    NASA Astrophysics Data System (ADS)

    Mollica, Giulia; Ziarelli, Fabio; Tintaru, Aura; Thureau, Pierre; Viel, Stéphane

    2012-05-01

    A simple procedure to effectively suppress background signals arising from various probe head components (e.g. stator, rotors, inserts) in solid state NMR is presented. Similarly to the ERETIC™ method, which uses an electronic signal as an internal standard for quantification, the proposed scheme is based on an electronically generated time-dependent signal that is injected into the receiver coil of the NMR probe head during signal acquisition. More specifically, the line shape, width and frequency of this electronic signal are determined by deconvoluting the background signal in the frequency domain. This deconvoluted signal is then converted into a time-dependent function through inverse Fourier Transform, which is used to generate the shaped pulse that is fed into the receiver coil during the acquisition of the Free Induction Decay. The power of the shaped pulse is adjusted to match the intensity of the background signal, and its phase is shifted by 180° with respect to the receiver reference phase. This so-called Electronic Mixing-Mediated Annihilation (EMMA) methodology is demonstrated here with a 13C Single Pulse Magic Angle Spinning spectrum of an isotopically enriched 13C histidine solid sample recorded under quantitative conditions.

  9. Calcium signaling and the secretory activity of bile duct epithelia.

    PubMed

    Amaya, Maria Jimena; Nathanson, Michael H

    2014-06-01

    Cytosolic calcium (Cai(2+)) is a second messenger that is important for the regulation of secretion in many types of tissues. Bile duct epithelial cells, or cholangiocytes, are polarized epithelia that line the biliary tree in liver and are responsible for secretion of bicarbonate and other solutes into bile. Cai(2+) signaling plays an important role in the regulation of secretion by cholangiocytes, and this review discusses the machinery involved in the formation of Ca(2+) signals in cholangiocytes, along with the evidence that these signals regulate ductular secretion. Finally, this review discusses the evidence that impairments in cholangiocyte Ca(2+) signaling play a primary role in the pathogenesis of cholestatic disorders, in which hepatic bile secretion is impaired. PMID:24612866

  10. Ammonium Activates Ouabain-Activated Signalling Pathway in Astrocytes: Therapeutic Potential of Ouabain Antagonist

    PubMed Central

    Song, Dan; Du, Ting

    2014-01-01

    The causal role of ammonium in hepatic encephalopathy was identified in 1930s. Astroglial cells are primary cellular elements of hepatic encephalopathy which conceptually, can be considered a toxic astrogliopathology. Previously we have reported that acute exposure to ammonium activated ouabain/Na,K-ATPase signalling pathway, which includes Src, EGF receptor, Raf, Ras, MEK and ERK1/2. Chronic incubation of astrocytes with ammonium increased production of endogenous ouabain-like compound. Ouabain antagonist canrenone abolished effects of ammonium on astrocytic swelling, ROS production, and upregulation of gene expression and function of TRPC1 and Cav1.2. However, ammonium induces multiple pathological modifications in astrocytes, and some of them may be not related to this signalling pathway. In this review, we focus on the effect of ammonium on ouabain/Na,K-ATPase signalling pathway and its involvement in ammonium-induced ROS production, cell swelling and aberration of Ca2+ signals in astrocytes. We also briefly discuss Na,K-ATPase, EGF receptor, endogenous ouabain and ouabain antagonist. PMID:25342941

  11. Active State Model for Autonomous Systems

    NASA Technical Reports Server (NTRS)

    Park, Han; Chien, Steve; Zak, Michail; James, Mark; Mackey, Ryan; Fisher, Forest

    2003-01-01

    The concept of the active state model (ASM) is an architecture for the development of advanced integrated fault-detection-and-isolation (FDI) systems for robotic land vehicles, pilotless aircraft, exploratory spacecraft, or other complex engineering systems that will be capable of autonomous operation. An FDI system based on the ASM concept would not only provide traditional diagnostic capabilities, but also integrate the FDI system under a unified framework and provide mechanism for sharing of information between FDI subsystems to fully assess the overall health of the system. The ASM concept begins with definitions borrowed from psychology, wherein a system is regarded as active when it possesses self-image, self-awareness, and an ability to make decisions itself, such that it is able to perform purposeful motions and other transitions with some degree of autonomy from the environment. For an engineering system, self-image would manifest itself as the ability to determine nominal values of sensor data by use of a mathematical model of itself, and selfawareness would manifest itself as the ability to relate sensor data to their nominal values. The ASM for such a system may start with the closed-loop control dynamics that describe the evolution of state variables. As soon as this model was supplemented with nominal values of sensor data, it would possess self-image. The ability to process the current sensor data and compare them with the nominal values would represent self-awareness. On the basis of self-image and self-awareness, the ASM provides the capability for self-identification, detection of abnormalities, and self-diagnosis.

  12. PROKR2 missense mutations associated with Kallmann syndrome impair receptor signalling activity.

    PubMed

    Monnier, Carine; Dodé, Catherine; Fabre, Ludovic; Teixeira, Luis; Labesse, Gilles; Pin, Jean-Philippe; Hardelin, Jean-Pierre; Rondard, Philippe

    2009-01-01

    Kallmann syndrome (KS) combines hypogonadism due to gonadotropin-releasing hormone deficiency, and anosmia or hyposmia, related to defective olfactory bulb morphogenesis. In a large series of KS patients, ten different missense mutations (p.R85C, p.R85H, p.R164Q, p.L173R, p.W178S, p.Q210R, p.R268C, p.P290S, p.M323I, p.V331M) have been identified in the gene encoding the G protein-coupled receptor prokineticin receptor-2 (PROKR2), most often in the heterozygous state. Many of these mutations were, however, also found in clinically unaffected individuals, thus raising the question of their actual implication in the KS phenotype. We reproduced each of the ten mutations in a recombinant murine Prokr2, and tested their effects on the signalling activity in transfected HEK-293 cells, by measuring intracellular calcium release upon ligand-activation of the receptor. We found that all mutated receptors except one (M323I) had decreased signalling activities. These could be explained by different defective mechanisms. Three mutations (L173R, W178S, P290S) impaired cell surface-targeting of the receptor. One mutation (Q210R) abolished ligand-binding. Finally, five mutations (R85C, R85H, R164Q, R268C, V331M) presumably impaired G protein-coupling of the receptor. In addition, when wild-type and mutant receptors were coexpressed in HEK-293 cells, none of the mutant receptors that were retained within the cells did affect cell surface-targeting of the wild-type receptor, and none of the mutant receptors properly addressed at the plasma membrane did affect wild-type receptor signalling activity. This argues against a dominant negative effect of the mutations in vivo. PMID:18826963

  13. PROKR2 missense mutations associated with Kallmann syndrome impair receptor signalling activity

    PubMed Central

    Monnier, Carine; Dodé, Catherine; Fabre, Ludovic; Teixeira, Luis; Labesse, Gilles; Pin, Jean-Philippe; Hardelin, Jean-Pierre; Rondard, Philippe

    2009-01-01

    Kallmann syndrome (KS) combines hypogonadism due to gonadotropin-releasing hormone deficiency, and anosmia or hyposmia, related to defective olfactory bulb morphogenesis. In a large series of KS patients, ten different missense mutations (p.R85C, p.R85H, p.R164Q, p.L173R, p.W178S, p.Q210R, p.R268C, p.P290S, p.M323I, p.V331M) have been identified in the gene encoding the G protein-coupled receptor prokineticin receptor-2 (PROKR2), most often in the heterozygous state. Many of these mutations were, however, also found in clinically unaffected individuals, thus raising the question of their actual implication in the KS phenotype. We reproduced each of the ten mutations in a recombinant murine Prokr2, and tested their effects on the signalling activity in transfected HEK-293 cells, by measuring intracellular calcium release upon ligand-activation of the receptor. We found that all mutated receptors except one (M323I) had decreased signalling activities. These could be explained by different defective mechanisms. Three mutations (L173R, W178S, P290S) impaired cell surface-targeting of the receptor. One mutation (Q210R) abolished ligand-binding. Finally, five mutations (R85C, R85H, R164Q, R268C, V331M) presumably impaired G protein-coupling of the receptor. In addition, when wild-type and mutant receptors were coexpressed in HEK-293 cells, none of the mutant receptors that were retained within the cells did affect cell surface-targeting of the wild-type receptor, and none of the mutant receptors properly addressed at the plasma membrane did affect wild-type receptor signalling activity. This argues against a dominant negative effect of the mutations in vivo. PMID:18826963

  14. New Constitutively Active Phytochromes Exhibit Light-Independent Signaling Activity1[OPEN

    PubMed Central

    Jeong, A-Reum; Lee, Si-Seok; Han, Yun-Jeong; Shin, Ah-Young; Baek, Ayoung; Ahn, Taeho; Kim, Min-Gon; Kim, Young Soon; Lee, Keun Woo; Nagatani, Akira

    2016-01-01

    Plant phytochromes are photoreceptors that mediate a variety of photomorphogenic responses. There are two spectral photoisomers, the red light-absorbing Pr and far-red light-absorbing Pfr forms, and the photoreversible transformation between the two forms is important for the functioning of phytochromes. In this study, we isolated a Tyr-268-to-Val mutant of Avena sativa phytochrome A (AsYVA) that displayed little photoconversion. Interestingly, transgenic plants of AsYVA showed light-independent phytochrome signaling with a constitutive photomorphogenic (cop) phenotype that is characterized by shortened hypocotyls and open cotyledons in the dark. In addition, the corresponding Tyr-303-to-Val mutant of Arabidopsis (Arabidopsis thaliana) phytochrome B (AtYVB) exhibited nuclear localization and interaction with phytochrome-interacting factor 3 (PIF3) independently of light, conferring a constitutive photomorphogenic development to its transgenic plants, which is comparable to the first constitutively active version of phytochrome B (YHB; Tyr-276-to-His mutant). We also found that chromophore ligation was required for the light-independent interaction of AtYVB with PIF3. Moreover, we demonstrated that AtYVB did not exhibit phytochrome B activity when it was localized in the cytosol by fusion with the nuclear export signal and that AsYVA exhibited the full activity of phytochrome A when localized in the nucleus by fusion with the nuclear localization signal. Furthermore, the corresponding Tyr-269-to-Val mutant of Arabidopsis phytochrome A (AtYVA) exhibited similar cop phenotypes in transgenic plants to AsYVA. Collectively, these results suggest that the conserved Tyr residues in the chromophore-binding pocket play an important role during the Pr-to-Pfr photoconversion of phytochromes, providing new constitutively active alleles of phytochromes by the Tyr-to-Val mutation. PMID:27325667

  15. Passive resting state and history of antagonist muscle activity shape active extensions in an insect limb.

    PubMed

    Ache, Jan M; Matheson, Thomas

    2012-05-01

    Limb movements can be driven by muscle contractions, external forces, or intrinsic passive forces. For lightweight limbs like those of insects or small vertebrates, passive forces can be large enough to overcome the effects of gravity and may even generate limb movements in the absence of active muscle contractions. Understanding the sources and actions of such forces is therefore important in understanding motor control. We describe passive properties of the femur-tibia joint of the locust hind leg. The resting angle is determined primarily by passive properties of the relatively large extensor tibiae muscle and is influenced by the history of activation of the fast extensor tibiae motor neuron. The resting angle is therefore better described as a history-dependent resting state. We selectively stimulated different flexor tibiae motor neurons to generate a range of isometric contractions of the flexor tibiae muscle and then stimulated the fast extensor tibiae motor neuron to elicit active tibial extensions. Residual forces in the flexor muscle have only a small effect on subsequent active extensions, but the effect is larger for distal than for proximal flexor motor neurons and varies with the strength of flexor activation. We conclude that passive properties of a lightweight limb make substantial and complex contributions to the resting state of the limb that must be taken into account in the patterning of neuronal control signals driving its active movements. Low variability in the effects of the passive forces may permit the nervous system to accurately predict their contributions to behavior. PMID:22357791

  16. Notch Signaling Activation in Pediatric Low-Grade Astrocytoma

    PubMed Central

    Brandt, William D.; Schreck, Karisa C.; Bar, Eli E.; Taylor, Isabella; Marchionni, Luigi; Raabe, Eric; Eberhart, Charles G.; Rodriguez, Fausto J.

    2014-01-01

    Pilocytic astrocytoma (PA) is the most common primary brain tumor in children; various signaling pathways have been implicated in its biology. The Notch signaling pathway has been found to play a role in development, stem cell biology, and the pathogenesis of several cancers but its role in PA has not been investigated. We studied alterations in Notch signaling components in tumor tissue from 18 patients with PA and 4 with other low-grade astrocytomas to identify much needed therapeutic targets. We found that Notch pathway members were overexpressed at the mRNA (NOTCH1, NOTCH2, HEY1, HEY2) and protein (HES1) levels in PAs at various anatomical sites compared to non-neoplastic brain samples. These changes were not associated with specific BRAF alterations. Inhibiting the Notch pathway in the pediatric low-grade astrocytoma cell lines Res 186 and Res 259 using either RNA interference or a γ-secretase inhibitor resulted in variable but significant reduction in cell growth and migration. This study suggests a potential role for Notch signaling in pediatric low-grade astrocytoma tumorigenesis and that Notch signaling may be a viable pathway therapeutic target. PMID:25575134

  17. Notch signaling activation in pediatric low-grade astrocytoma.

    PubMed

    Brandt, William D; Schreck, Karisa C; Bar, Eli E; Taylor, Isabella; Marchionni, Luigi; Raabe, Eric; Eberhart, Charles G; Rodriguez, Fausto J

    2015-02-01

    Pilocytic astrocytoma (PA) is the most common primary brain tumor in children; various signaling pathways have been implicated in its biology. The Notch signaling pathway has been found to play a role in the development, stem cell biology, and pathogenesis of several cancers, but its role in PA has not been investigated. We studied alterations in Notch signaling components in tumor tissue from 18 patients with PA and 4 with other low-grade astrocytomas to identify much needed therapeutic targets. We found that Notch pathway members were overexpressed at the mRNA (NOTCH1, NOTCH2, HEY1, HEY2) and protein (HES1) levels in PAs at various anatomic sites compared with non-neoplastic brain samples. These changes were not associated with specific BRAF alterations. Inhibiting the Notch pathway in the pediatric low-grade astrocytoma cell lines Res186 and Res259 using either RNA interference or a γ-secretase inhibitor resulted in variable, but significant, reduction in cell growth and migration. This study suggests a potential role for Notch signaling in pediatric low-grade astrocytoma tumorigenesis and that Notch signaling may be a viable pathway therapeutic target. PMID:25575134

  18. Steady-state ab initio theory of lasers with injected signals

    NASA Astrophysics Data System (ADS)

    Cerjan, Alexander; Stone, A. Douglas

    2014-07-01

    We present an ab initio treatment of the steady-state of lasers with injected signals that describes a regime, valid for microlasers, in which the locking transition is dominated by cross saturation and spatial hole burning. The theory goes beyond standard approaches and treats multimode lasing with injected signals and finds the possibility of partially locked states and as well as repulsion of the free-running frequencies from the injected signal. The theory agrees well with exact integration of the full wave and matter equations for the system. It can also describe accurately complex modern lasers structures and is applied to the example of deformed disk lasers. We show that in the case of a one-dimensional cavity in the locked or regenerative amplifier regime the theory reduces to an improved version of the Adler equations in the appropriate limit.

  19. GSK621 Targets Glioma Cells via Activating AMP-Activated Protein Kinase Signalings

    PubMed Central

    Jiang, Hong; Liu, Wei; Zhan, Shi-Kun; Pan, Yi-Xin; Bian, Liu-Guan; Sun, Bomin; Sun, Qing-Fang; Pan, Si-Jian

    2016-01-01

    Here, we studied the anti-glioma cell activity by a novel AMP-activated protein kinase (AMPK) activator GSK621. We showed that GSK621 was cytotoxic to human glioma cells (U87MG and U251MG lines), possibly via provoking caspase-dependent apoptotic cell death. Its cytotoxicity was alleviated by caspase inhibitors. GSK621 activated AMPK to inhibit mammalian target of rapamycin (mTOR) and downregulate Tetraspanin 8 (Tspan8) in glioma cells. AMPK inhibition, through shRNA knockdown of AMPKα or introduction of a dominant negative (T172A) AMPKα, almost reversed GSK621-induced AMPK activation, mTOR inhibition and Tspan8 degradation. Consequently, GSK621’s cytotoxicity in glioma cells was also significantly attenuated by AMPKα knockdown or mutation. Further studies showed that GSK621, at a relatively low concentration, significantly potentiated temozolomide (TMZ)’s sensitivity and lethality against glioma cells. We summarized that GSK621 inhibits human glioma cells possibly via activating AMPK signaling. This novel AMPK activator could be a novel and promising anti-glioma cell agent. PMID:27532105

  20. Multiplexing free-space optical signals using superimposed collinear orbital angular momentum states

    NASA Astrophysics Data System (ADS)

    Lin, J.; Yuan, X.-C.; Tao, S. H.; Burge, R. E.

    2007-07-01

    As a proof of concept, we experimentally demonstrate multiplexing of free-space optical signals in multiple channels labeled with different states of orbital angular momentum. The multiplexing process is carried out by a dynamic liquid-crystal spatial light modulator, while the phase function is calculated by an iterative algorithm. A binary amplitude computer-generated hologram serves as a demultiplexer.

  1. PKCδ activated by c-MET enhances infiltration of human glioblastoma cells through NOTCH2 signaling

    PubMed Central

    Kang, Seok-Gu; Kim, Rae-Kwon; Cui, Yan-Hong; Lee, Hae-June; Kim, Min-Jung; Lee, Jae-Seong; Kim, In-Gyu; Suh, Yongjoon; Lee, Su-Jae

    2016-01-01

    Poor prognosis of glioblastoma (GBM) is attributable to the propensity of tumor cells to infiltrate into the brain parenchyma. Protein kinase C (PKC) isozymes are highly expressed or aberrantly activated in GBM. However, how this signaling node translates to GBM cell invasiveness remains unknown. Here, we report that among PKC isoforms, PKCδ is strongly associated with infiltration of GBM cells. Notably, PKCδ enhanced Tyr418 phosphorylation of the non-receptor tyrosine kinase SRC, which in turn activated STAT3 and subsequent NOTCH2 signaling, ultimately leading to GBM cell invasiveness. Furthermore, we showed that PKCδ was aberrantly activated in GBM cells by c-MET, a receptor tyrosine kinase hyperactivated in GBM. In agreement, inhibition either component in the c-MET/PKCδ/SRC/STAT3 signaling axis effectively blocked the NOTCH2 signaling and invasiveness of GBM cells. Taken together, our findings shed a light on the signaling mechanisms behind the constitutive activation of PKCδ signaling in GBM. PMID:26700818

  2. Methamphetamine-induced neurotoxicity and microglial activation are not mediated by fractalkine receptor signaling

    PubMed Central

    Thomas, David M.; Francescutti-Verbeem, Dina M.; Kuhn, Donald M.

    2009-01-01

    Methamphetamine (METH) damages dopamine (DA) nerve endings by a process that has been linked to microglial activation but the signaling pathways that mediate this response have not yet been delineated. Cardona et al. [Nat. Neurosci. 9 (2006), 917] recently identified the microglial-specific fractalkine receptor (CX3CR1) as an important mediator of MPTP-induced neurodegeneration of DA neurons. Because the CNS damage caused by METH and MPTP is highly selective for the DA neuronal system in mouse models of neurotoxicity, we hypothesized that the CX3CR1 plays a role in METH-induced neurotoxicity and microglial activation. Mice in which the CX3CR1 gene has been deleted and replaced with a cDNA encoding enhanced green fluorescent protein (eGFP) were treated with METH and examined for striatal neurotoxicity. METH depleted DA, caused microglial activation, and increased body temperature in CX3CR1 knockout mice to the same extent and over the same time course seen in wild-type controls. The effects of METH in CX3CR1 knockout mice were not gender-dependent and did not extend beyond the striatum. Striatal microglia expressing eGFP constitutively show morphological changes after METH that are characteristic of activation. This response was restricted to the striatum and contrasted sharply with unresponsive eGFP-microglia in surrounding brain areas that are not damaged by METH. We conclude from these studies that CX3CR1 signaling does not modulate METH neurotoxicity or microglial activation. Furthermore, it appears that striatal-resident microglia respond to METH with an activation cascade and then return to a surveying state without undergoing apoptosis or migration. PMID:18410508

  3. Chloroplast Activity and 3'phosphadenosine 5'phosphate Signaling Regulate Programmed Cell Death in Arabidopsis.

    PubMed

    Bruggeman, Quentin; Mazubert, Christelle; Prunier, Florence; Lugan, Raphaël; Chan, Kai Xun; Phua, Su Yin; Pogson, Barry James; Krieger-Liszkay, Anja; Delarue, Marianne; Benhamed, Moussa; Bergounioux, Catherine; Raynaud, Cécile

    2016-03-01

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

  4. Cell signaling through protein kinase C oxidation and activation.

    PubMed

    Cosentino-Gomes, Daniela; Rocco-Machado, Nathália; Meyer-Fernandes, José Roberto

    2012-01-01

    Due to the growing importance of cellular signaling mediated by reactive oxygen species (ROS), proteins that are reversibly modulated by these reactant molecules are of high interest. In this context, protein kinases and phosphatases, which act coordinately in the regulation of signal transduction through the phosphorylation and dephosphorylation of target proteins, have been described to be key elements in ROS-mediated signaling events. The major mechanism by which these proteins may be modified by oxidation involves the presence of key redox-sensitive cysteine residues. Protein kinase C (PKC) is involved in a variety of cellular signaling pathways. These proteins have been shown to contain a unique structural feature that is susceptible to oxidative modification. A large number of scientific studies have highlighted the importance of ROS as a second messenger in numerous cellular processes, including cell proliferation, gene expression, adhesion, differentiation, senescence, and apoptosis. In this context, the goal of this review is to discuss the mechanisms by which PKCs are modulated by ROS and how these processes are involved in the cellular response. PMID:23109817

  5. Phosphoproteomic analysis of anaplastic lymphoma kinase (ALK) downstream signaling pathways identifies signal transducer and activator of transcription 3 as a functional target of activated ALK in neuroblastoma cells

    PubMed Central

    Sattu, Kamaraj; Hochgräfe, Falko; Wu, Jianmin; Umapathy, Ganesh; Schönherr, Christina; Ruuth, Kristina; Chand, Damini; Witek, Barbara; Fuchs, James; Li, Pui-Kai; Hugosson, Fredrik; Daly, Roger J; Palmer, Ruth H; Hallberg, Bengt

    2013-01-01

    Activation of the anaplastic lymphoma kinase (ALK) receptor tyrosine kinase is a key oncogenic mechanism in a growing number of tumor types. In the majority of cases, ALK is activated by fusion with a dimerizing partner protein as a result of chromosomal translocation events, most studied in the case of the nucleophosmin–ALK and echinoderm microtubule-associated protein-like 4–ALK oncoproteins. It is now also appreciated that the full-length ALK receptor can be activated by point mutations and by deletions within the extracellular domain, such as those observed in neuroblastoma. Several studies have employed phosphoproteomics approaches to find substrates of ALK fusion proteins. In this study, we used MS-based phosphotyrosine profiling to characterize phosphotyrosine signaling events associated with the full-length ALK receptor. A number of previously identified and novel targets were identified. One of these, signal transducer and activator of transcription 3 (STAT3), has previously been observed to be activated in response to oncogenic ALK signaling, but the significance of this in signaling from the full-length ALK receptor has not been explored further. We show here that activated ALK robustly activates STAT3 on Tyr705 in a number of independent neuroblastoma cell lines. Furthermore, knockdown of STAT3 by RNA interference resulted in a reduction in myelocytomatosis neuroblastom (MYCN) protein levels downstream of ALK signaling. These observations, together with a decreased level of MYCN and inhibition of neuroblastoma cell growth in the presence of STAT3 inhibitors, suggest that activation of STAT3 is important for ALK signaling activity in neuroblastoma. PMID:23889739

  6. AMP-activated Protein Kinase Signaling Activation by Resveratrol Modulates Amyloid-β Peptide Metabolism*

    PubMed Central

    Vingtdeux, Valérie; Giliberto, Luca; Zhao, Haitian; Chandakkar, Pallavi; Wu, Qingli; Simon, James E.; Janle, Elsa M.; Lobo, Jessica; Ferruzzi, Mario G.; Davies, Peter; Marambaud, Philippe

    2010-01-01

    Alzheimer disease is an age-related neurodegenerative disorder characterized by amyloid-β (Aβ) peptide deposition into cerebral amyloid plaques. The natural polyphenol resveratrol promotes anti-aging pathways via the activation of several metabolic sensors, including the AMP-activated protein kinase (AMPK). Resveratrol also lowers Aβ levels in cell lines; however, the underlying mechanism responsible for this effect is largely unknown. Moreover, the bioavailability of resveratrol in the brain remains uncertain. Here we show that AMPK signaling controls Aβ metabolism and mediates the anti-amyloidogenic effect of resveratrol in non-neuronal and neuronal cells, including in mouse primary neurons. Resveratrol increased cytosolic calcium levels and promoted AMPK activation by the calcium/calmodulin-dependent protein kinase kinase-β. Direct pharmacological and genetic activation of AMPK lowered extracellular Aβ accumulation, whereas AMPK inhibition reduced the effect of resveratrol on Aβ levels. Furthermore, resveratrol inhibited the AMPK target mTOR (mammalian target of rapamycin) to trigger autophagy and lysosomal degradation of Aβ. Finally, orally administered resveratrol in mice was detected in the brain where it activated AMPK and reduced cerebral Aβ levels and deposition in the cortex. These data suggest that resveratrol and pharmacological activation of AMPK have therapeutic potential against Alzheimer disease. PMID:20080969

  7. Kurarinol induces hepatocellular carcinoma cell apoptosis through suppressing cellular signal transducer and activator of transcription 3 signaling

    SciTech Connect

    Shu, Guangwen; Yang, Jing; Zhao, Wenhao; Xu, Chan; Hong, Zongguo; Mei, Zhinan; Yang, Xinzhou

    2014-12-01

    Kurarinol is a flavonoid isolated from roots of the medical plant Sophora flavescens. However, its cytotoxic activity against hepatocellular carcinoma (HCC) cells and toxic effects on mammalians remain largely unexplored. Here, the pro-apoptotic activities of kurarinol on HCC cells and its toxic impacts on tumor-bearing mice were evaluated. The molecular mechanisms underlying kurarinol-induced HCC cell apoptosis were also investigated. We found that kurarinol dose-dependently provoked HepG2, Huh-7 and H22 HCC cell apoptosis. In addition, kurarinol gave rise to a considerable decrease in the transcriptional activity of signal transducer and activator of transcription 3 (STAT3) in HCC cells. Suppression of STAT3 signaling is involved in kurarinol-induced HCC cell apoptosis. In vivo studies showed that kurarinol injection substantially induced transplanted H22 cell apoptosis with low toxic impacts on tumor-bearing mice. Similarly, the transcriptional activity of STAT3 in transplanted tumor tissues was significantly suppressed after kurarinol treatment. Collectively, our current research demonstrated that kurarinol has the capacity of inducing HCC cell apoptosis both in vitro and in vivo with undetectable toxic impacts on the host. Suppressing STAT3 signaling is implicated in kurarinol-mediated HCC cell apoptosis. - Highlights: • Kurarinol induces hepatocellular carcinoma (HCC) cell apoptosis. • Kurarinol induces HCC cell apoptosis via inhibiting STAT3. • Kurarinol exhibits low toxic effects on tumor-bearing animals.

  8. Parallels between immune driven-hematopoiesis and T cell activation: 3 signals that relay inflammatory stress to the bone marrow

    SciTech Connect

    Libregts, Sten F.W.M.; Nolte, Martijn A.

    2014-12-10

    Quiescence, self-renewal, lineage commitment and differentiation of hematopoietic stem cells (HSCs) towards fully mature blood cells are a complex process that involves both intrinsic and extrinsic signals. During steady-state conditions, most hematopoietic signals are provided by various resident cells inside the bone marrow (BM), which establish the HSC micro-environment. However, upon infection, the hematopoietic process is also affected by pathogens and activated immune cells, which illustrates an effective feedback mechanism to hematopoietic stem and progenitor cells (HSPCs) via immune-mediated signals. Here, we review the impact of pathogen-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs), costimulatory molecules and pro-inflammatory cytokines on the quiescence, proliferation and differentiation of HSCs and more committed progenitors. As modulation of HSPC function via these immune-mediated signals holds an interesting parallel with the “three-signal-model” described for the activation and differentiation of naïve T-cells, we propose a novel “three-signal” concept for immune-driven hematopoiesis. In this model, the recognition of PAMPs and DAMPs will activate HSCs and induce proliferation, while costimulatory molecules and pro-inflammatory cytokines confer a second and third signal, respectively, which further regulate expansion, lineage commitment and differentiation of HSPCs. We review the impact of inflammatory stress on hematopoiesis along these three signals and we discuss whether they act independently from each other or that concurrence of these signals is important for an adequate response of HSPCs upon infection. - Highlights: • Inflammation and infection have a direct impact on hematopoiesis in the bone marrow. • We draw a striking parallel between immune-driven hematopoiesis and T cell activation. • We review how PAMPs and DAMPs, costimulation and cytokines influence HSPC function.

  9. Multi-State Transition Kinetics of Intracellular Signaling Molecules by Single-Molecule Imaging Analysis.

    PubMed

    Matsuoka, Satomi; Miyanaga, Yukihiro; Ueda, Masahiro

    2016-01-01

    The chemotactic signaling of eukaryotic cells is based on a chain of interactions between signaling molecules diffusing on the cell membrane and those shuttling between the membrane and cytoplasm. In this chapter, we describe methods to quantify lateral diffusion and reaction kinetics on the cell membrane. By the direct visualization and statistic analyses of molecular Brownian movement achieved by single-molecule imaging techniques, multiple states of membrane-bound molecules are successfully revealed with state transition kinetics. Using PTEN, a phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5)P3) 3'-phosphatase, in Dictyostelium discoideum undergoing chemotaxis as a model, each process of the analysis is described in detail. The identified multiple state kinetics provides an essential clue to elucidating the molecular mechanism of chemoattractant-induced dynamic redistribution of the signaling molecule asymmetrically on the cell membrane. Quantitative parameters for molecular reactions and diffusion complement a conventional view of the chemotactic signaling system, where changing a static network of molecules connected by causal relationships into a spatiotemporally dynamic one permits a mathematical description of stochastic migration of the cell along a shallow chemoattractant gradient. PMID:27271914

  10. Msx2 promotes cardiovascular calcification by activating paracrine Wnt signals.

    PubMed

    Shao, Jian-Su; Cheng, Su-Li; Pingsterhaus, Joyce M; Charlton-Kachigian, Nichole; Loewy, Arleen P; Towler, Dwight A

    2005-05-01

    In diabetic LDLR-/- mice, an ectopic BMP2-Msx2 gene regulatory program is upregulated in association with vascular calcification. We verified the procalcific actions of aortic Msx2 expression in vivo. CMV-Msx2 transgenic (CMV-Msx2Tg(+)) mice expressed 3-fold higher levels of aortic Msx2 than nontransgenic littermates. On high-fat diets, CMV-Msx2Tg(+) mice exhibited marked cardiovascular calcification involving aortic and coronary tunica media. This corresponded to regions of Msx2 immunoreactivity in adjacent adventitial myofibroblasts, suggesting a potential paracrine osteogenic signal. To better understand Msx2-regulated calcification, we studied actions in 10T1/2 cells. We found that conditioned media from Msx2-transduced 10T1/2 cells (Msx2-CM) is both pro-osteogenic and adipostatic; these features are characteristic of Wnt signaling. Msx2-CM stimulated Wnt-dependent TCF/LEF transcription, and Msx2-transduced cells exhibited increased nuclear beta-catenin localization with concomitant alkaline phosphatase induction. Msx2 upregulated Wnt3a and Wnt7a but downregulated expression of the canonical inhibitor Dkk1. Dkk1 treatment reversed osteogenic and adipostatic actions of Msx2. Teriparatide, a PTH1R agonist that inhibits murine vascular calcification, suppressed vascular BMP2-Msx2-Wnt signaling. Analyses of CMV-Msx2Tg(+) mice confirmed that Msx2 suppresses aortic Dkk1 and upregulates vascular Wnts; moreover, TOPGAL(+) (Wnt reporter); CMV-Msx2Tg(+) mice exhibited augmented aortic LacZ expression. Thus, Msx2-expressing cells elaborated an osteogenic milieu that promotes vascular calcification in part via paracrine Wnt signals. PMID:15841209

  11. Noise exposure immediately activates cochlear mitogen-activated protein kinase signaling

    PubMed Central

    Alagramam, Kumar N.; Stepanyan, Ruben; Jamesdaniel, Samson; Chen, Daniel H.-C.; Davis, Rickie R.

    2015-01-01

    Noise-induced hearing loss (NIHL) is a major public health issue worldwide. Uncovering the early molecular events associated with NIHL would reveal mechanisms leading to the hearing loss. Our aim is to investigate the immediate molecular responses after different levels of noise exposure and identify the common and distinct pathways that mediate NIHL. Previous work showed mice exposed to 116 decibels sound pressure level (dB SPL) broadband noise for 1 h had greater threshold shifts than the mice exposed to 110 dB SPL broadband noise, hence we used these two noise levels in this study. Groups of 4–8-week-old CBA/CaJ mice were exposed to no noise (control) or to broadband noise for 1 h, followed by transcriptome analysis of total cochlear RNA isolated immediately after noise exposure. Previously identified and novel genes were found in all data sets. Following exposure to noise at 116 dB SPL, the earliest responses included up-regulation of 243 genes and down-regulation of 61 genes, while a similar exposure at 110 dB SPL up-regulated 155 genes and down-regulated 221 genes. Bioinformatics analysis indicated that mitogen-activated protein kinase (MAPK) signaling was the major pathway in both levels of noise exposure. Nevertheless, both qualitative and quantitative differences were noticed in some MAPK signaling genes, after exposure to different noise levels. Cacna1b, Cacna1g, and Pla2g6, related to calcium signaling were down-regulated after 110 dB SPL exposure, while the fold increase in the expression of Fos was relatively lower than what was observed after 116 dB SPL exposure. These subtle variations provide insight on the factors that may contribute to the differences in NIHL despite the activation of a common pathway. PMID:25387536

  12. LAF1, a MYB transcription activator for phytochrome A signaling

    PubMed Central

    Ballesteros, María L.; Bolle, Cordelia; Lois, Luisa M.; Moore, James M.; Vielle-Calzada, Jean-Philippe; Grossniklaus, Ueli; Chua, Nam-Hai

    2001-01-01

    The photoreceptor phytochrome (phy) A has a well-defined role in regulating gene expression in response to specific light signals. Here, we describe a new Arabidopsis mutant, laf1 (long after far-red light 1) that has an elongated hypocotyl specifically under far-red light. Gene expression studies showed that laf1 has reduced responsiveness to continuous far-red light but retains wild-type responses to other light wavelengths. As far-red light is only perceived by phyA, our results suggest that LAF1 is specifically involved in phyA signal transduction. Further analyses revealed that laf1 is affected in a subset of phyA-dependent responses and the phenotype is more severe at low far-red fluence rates. LAF1 encodes a nuclear protein with strong homology with the R2R3–MYB family of DNA-binding proteins. Experiments using yeast cells identified a transactivation domain in the C-terminal portion of the protein. LAF1 is constitutively targeted to the nucleus by signals in its N-terminal portion, and the full-length protein accumulates in distinct nuclear speckles. This accumulation in speckles is abolished by a point mutation in a lysine residue (K258R), which might serve as a modification site by a small ubiquitin-like protein (SUMO). PMID:11581165

  13. Temporal protein expression pattern in intracellular signalling cascade during T-cell activation: a computational study.

    PubMed

    Ganguli, Piyali; Chowdhury, Saikat; Bhowmick, Rupa; Sarkar, Ram Rup

    2015-10-01

    Various T-cell co-receptor molecules and calcium channel CRAC play a pivotal role in the maintenance of cell's functional responses by regulating the production of effector molecules (mostly cytokines) that aids in immune clearance and also maintaining the cell in a functionally active state. Any defect in these co-receptor signalling pathways may lead to an altered expression pattern of the effector molecules. To study the propagation of such defects with time and their effect on the intracellular protein expression patterns, a comprehensive and largest pathway map of T-cell activation network is reconstructed manually. The entire pathway reactions are then translated using logical equations and simulated using the published time series microarray expression data as inputs. After validating the model, the effect of in silico knock down of co-receptor molecules on the expression patterns of their downstream proteins is studied and simultaneously the changes in the phenotypic behaviours of the T-cell population are predicted, which shows significant variations among the proteins expression and the signalling routes through which the response is propagated in the cytoplasm. This integrative computational approach serves as a valuable technique to study the changes in protein expression patterns and helps to predict variations in the cellular behaviour. PMID:26564978

  14. Smelling chemosensory signals of males in anxious versus nonanxious condition increases state anxiety of female subjects.

    PubMed

    Albrecht, Jessica; Demmel, Maria; Schöpf, Veronika; Kleemann, Anna Maria; Kopietz, Rainer; May, Johanna; Schreder, Tatjana; Zernecke, Rebekka; Brückmann, Hartmut; Wiesmann, Martin

    2011-01-01

    The hypothesis of this experiment was that humans in an anxious state compared with a nonanxious state are able to increase anxiety levels in other humans via their body odors. Specifically, we hypothesized that male chemosensory anxiety signals compared with neutral chemosignals increase state anxiety of female subjects. Thirteen male subjects participated in 2 different sweat donation sessions: chemosignals were collected during participation in a high rope course (anxiety condition) and in an ergometer workout (neutral condition). State and trait anxiety were evaluated in 20 female odor recipients using Spielberger's state-trait anxiety inventory in a double-blind design. Comparison of state anxiety of odor donors between control and anxiety condition differed significantly indicating that our model of anxiety induction successfully led to the expected change in emotion. Comparison of state anxiety of odor recipients showed a trend toward higher state anxiety in the anxiety condition compared with the neutral condition after 5 min of odor exposure. After 20 min of odor exposure, state anxiety of female subjects was significantly higher during the perception of sweat collected during the anxiety condition in comparison with the perception of sweat collected during the neutral condition. This experiment gives evidence that male anxiety chemosignals compared with neutral chemosignals are capable of inducing an increased state anxiety in female subjects. PMID:20929974

  15. Proton transfer to flavin stabilizes the signaling state of the blue light receptor plant cryptochrome.

    PubMed

    Hense, Anika; Herman, Elena; Oldemeyer, Sabine; Kottke, Tilman

    2015-01-16

    Plant cryptochromes regulate the circadian rhythm, flowering time, and photomorphogenesis in higher plants as responses to blue light. In the dark, these photoreceptors bind oxidized FAD in the photolyase homology region (PHR). Upon blue light absorption, FAD is converted to the neutral radical state, the likely signaling state, by electron transfer via a conserved tryptophan triad and proton transfer from a nearby aspartic acid. Here we demonstrate, by infrared and time-resolved UV-visible spectroscopy on the PHR domain, that replacement of the aspartic acid Asp-396 with cysteine prevents proton transfer. The lifetime of the radical is decreased by 6 orders of magnitude. This short lifetime does not permit to drive conformational changes in the C-terminal extension that have been associated with signal transduction. Only in the presence of ATP do both the wild type and mutant form a long-lived radical state. However, in the mutant, an anion radical is formed instead of the neutral radical, as found previously in animal type I cryptochromes. Infrared spectroscopic experiments demonstrate that the light-induced conformational changes of the PHR domain are conserved in the mutant despite the lack of proton transfer. These changes are not detected in the photoreduction of the non-photosensory d-amino acid oxidase to the anion radical. In conclusion, formation of the anion radical is sufficient to generate a protein response in plant cryptochromes. Moreover, the intrinsic proton transfer is required for stabilization of the signaling state in the absence of ATP. PMID:25471375

  16. Proton Transfer to Flavin Stabilizes the Signaling State of the Blue Light Receptor Plant Cryptochrome*

    PubMed Central

    Hense, Anika; Herman, Elena; Oldemeyer, Sabine; Kottke, Tilman

    2015-01-01

    Plant cryptochromes regulate the circadian rhythm, flowering time, and photomorphogenesis in higher plants as responses to blue light. In the dark, these photoreceptors bind oxidized FAD in the photolyase homology region (PHR). Upon blue light absorption, FAD is converted to the neutral radical state, the likely signaling state, by electron transfer via a conserved tryptophan triad and proton transfer from a nearby aspartic acid. Here we demonstrate, by infrared and time-resolved UV-visible spectroscopy on the PHR domain, that replacement of the aspartic acid Asp-396 with cysteine prevents proton transfer. The lifetime of the radical is decreased by 6 orders of magnitude. This short lifetime does not permit to drive conformational changes in the C-terminal extension that have been associated with signal transduction. Only in the presence of ATP do both the wild type and mutant form a long-lived radical state. However, in the mutant, an anion radical is formed instead of the neutral radical, as found previously in animal type I cryptochromes. Infrared spectroscopic experiments demonstrate that the light-induced conformational changes of the PHR domain are conserved in the mutant despite the lack of proton transfer. These changes are not detected in the photoreduction of the non-photosensory d-amino acid oxidase to the anion radical. In conclusion, formation of the anion radical is sufficient to generate a protein response in plant cryptochromes. Moreover, the intrinsic proton transfer is required for stabilization of the signaling state in the absence of ATP. PMID:25471375

  17. Signaling-mediated cooperativity between glycoprotein Ib-IX and protease-activated receptors in thrombin-induced platelet activation.

    PubMed

    Estevez, Brian; Kim, Kyungho; Delaney, M Keegan; Stojanovic-Terpo, Aleksandra; Shen, Bo; Ruan, Changgeng; Cho, Jaehyung; Ruggeri, Zaverio M; Du, Xiaoping

    2016-02-01

    Thrombin-induced cellular response in platelets not only requires protease-activated receptors (PARs), but also involves another thrombin receptor, the glycoprotein Ib-IX complex (GPIb-IX). It remains controversial how thrombin binding to GPIb-IX stimulates platelet responses. It was proposed that GPIb-IX serves as a dock that facilitates thrombin cleavage of protease-activated receptors, but there are also reports suggesting that thrombin binding to GPIb-IX induces platelet activation independent of PARs. Here we show that GPIb is neither a passive thrombin dock nor a PAR-independent signaling receptor. We demonstrate a novel signaling-mediated cooperativity between PARs and GPIb-IX. Low-dose thrombin-induced PAR-dependent cell responses require the cooperativity of GPIb-IX signaling, and conversely, thrombin-induced GPIb-IX signaling requires cooperativity of PARs. This mutually dependent cooperativity requires a GPIb-IX-specific 14-3-3-Rac1-LIMK1 signaling pathway, and activation of this pathway also requires PAR signaling. The cooperativity between GPIb-IX signaling and PAR signaling thus drives platelet activation at low concentrations of thrombin, which are important for in vivo thrombosis. PMID:26585954

  18. Mitochondrial Oxidative Stress Corrupts Coronary Collateral Growth by Activating Adenosine Monophosphate Activated Kinase-α Signaling

    PubMed Central

    Pung, Yuh Fen; Sam, Wai Johnn; Stevanov, Kelly; Enrick, Molly; Chen, Chwen-Lih; Kolz, Christopher; Thakker, Prashanth; Hardwick, James P.; Chen, Yeong-Renn; Dyck, Jason R.B.; Yin, Liya; Chilian, William M.

    2015-01-01

    Objective Our goal was to determine the mechanism by which mitochondrial oxidative stress impairs collateral growth in the heart. Approach and Results Rats were treated with rotenone (mitochondrial complex I inhibitor that increases reactive oxygen species production) or sham-treated with vehicle and subjected to repetitive ischemia protocol for 10 days to induce coronary collateral growth. In control rats, repetitive ischemia increased flow to the collateral-dependent zone; however, rotenone treatment prevented this increase suggesting that mitochondrial oxidative stress compromises coronary collateral growth. In addition, rotenone also attenuated mitochondrial complex I activity and led to excessive mitochondrial aggregation. To further understand the mechanistic pathway(s) involved, human coronary artery endothelial cells were treated with 50 ng/ mL vascular endothelial growth factor, 1 µmol/L rotenone, and rotenone/vascular endothelial growth factor for 48 hours. Vascular endothelial growth factor induced robust tube formation; however, rotenone completely inhibited this effect (P<0.05 rotenone versus vascular endothelial growth factor treatment). Inhibition of tube formation by rotenone was also associated with significant increase in mitochondrial superoxide generation. Immunoblot analyses of human coronary artery endothelial cells with rotenone treatment showed significant activation of adenosine monophosphate activated kinase (AMPK)-α and inhibition of mammalian target of rapamycin and p70 ribosomal S6 kinase. Activation of AMPK-α suggested impairments in energy production, which was reflected by decrease in O2 consumption and bioenergetic reserve capacity of cultured cells. Knockdown of AMPK-α (siRNA) also preserved tube formation during rotenone, suggesting the negative effects were mediated by the activation of AMPK-α. Conversely, expression of a constitutively active AMPK-α blocked tube formation. Conclusions We conclude that activation of AMPK

  19. Smoothened regulates activator and repressor functions of Hedgehog signaling via two distinct mechanisms.

    PubMed

    Ogden, Stacey K; Casso, David J; Ascano, Manuel; Yore, Mark M; Kornberg, Thomas B; Robbins, David J

    2006-03-17

    The secreted protein Hedgehog (Hh) plays an important role in metazoan development and as a survival factor for many human tumors. In both cases, Hh signaling proceeds through the activation of the seven-transmembrane protein Smoothened (Smo), which is thought to convert the Gli family of transcription factors from transcriptional repressors to transcriptional activators. Here, we provide evidence that Smo signals to the Hh signaling complex, which consists of the kinesin-related protein Costal2 (Cos2), the protein kinase Fused (Fu), and the Drosophila Gli homolog cubitus interruptus (Ci), in two distinct manners. We show that many of the commonly observed molecular events following Hh signaling are not transmitted in a linear fashion but instead are activated through two signals that bifurcate at Smo to independently affect activator and repressor pools of Ci. PMID:16423832

  20. Prion-like Polymerization Underlies Signal Transduction in Antiviral Immune Defense and Inflammasome Activation

    PubMed Central

    Cai, Xin; Chen, Jueqi; Xu, Hui; Liu, Siqi; Jiang, Qiu-Xing; Halfmann, Randal; Chen, Zhijian J.

    2014-01-01

    SUMMARY Pathogens and cellular danger signals activate sensors such as RIG-I and NLRP3 to produce robust immune and inflammatory responses through respective adaptor proteins MAVS and ASC, which harbor essential N-terminal CARD and PYRIN domains, respectively. Here, we show that CARD and PYRIN function as bona fide prions in yeast and their prion forms are inducible by their respective upstream activators. Likewise, a yeast prion domain can functionally replace CARD and PYRIN in mammalian cell signaling. Mutations in MAVS and ASC that disrupt their prion activities in yeast also abrogate their ability to signal in mammalian cells. Furthermore, fibers of recombinant PYRIN can convert ASC into functional polymers capable of activating caspase-1. Remarkably, a conserved fungal NOD-like receptor and prion pair can functionally reconstitute signaling of NLRP3 and ASC PYRINs in mammalian cells. These results indicate that prion-like polymerization is a conserved signal transduction mechanism in innate immunity and inflammation. PMID:24630723

  1. Integration of light and metabolic signals for stem cell activation at the shoot apical meristem

    PubMed Central

    Pfeiffer, Anne; Janocha, Denis; Dong, Yihan; Medzihradszky, Anna; Schöne, Stefanie; Daum, Gabor; Suzaki, Takuya; Forner, Joachim; Langenecker, Tobias; Rempel, Eugen; Schmid, Markus; Wirtz, Markus; Hell, Rüdiger; Lohmann, Jan U

    2016-01-01

    A major feature of embryogenesis is the specification of stem cell systems, but in contrast to the situation in most animals, plant stem cells remain quiescent until the postembryonic phase of development. Here, we dissect how light and metabolic signals are integrated to overcome stem cell dormancy at the shoot apical meristem. We show on the one hand that light is able to activate expression of the stem cell inducer WUSCHEL independently of photosynthesis and that this likely involves inter-regional cytokinin signaling. Metabolic signals, on the other hand, are transduced to the meristem through activation of the TARGET OF RAPAMYCIN (TOR) kinase. Surprisingly, TOR is also required for light signal dependent stem cell activation. Thus, the TOR kinase acts as a central integrator of light and metabolic signals and a key regulator of stem cell activation at the shoot apex. DOI: http://dx.doi.org/10.7554/eLife.17023.001 PMID:27400267

  2. Integration of light and metabolic signals for stem cell activation at the shoot apical meristem.

    PubMed

    Pfeiffer, Anne; Janocha, Denis; Dong, Yihan; Medzihradszky, Anna; Schöne, Stefanie; Daum, Gabor; Suzaki, Takuya; Forner, Joachim; Langenecker, Tobias; Rempel, Eugen; Schmid, Markus; Wirtz, Markus; Hell, Rüdiger; Lohmann, Jan U

    2016-01-01

    A major feature of embryogenesis is the specification of stem cell systems, but in contrast to the situation in most animals, plant stem cells remain quiescent until the postembryonic phase of development. Here, we dissect how light and metabolic signals are integrated to overcome stem cell dormancy at the shoot apical meristem. We show on the one hand that light is able to activate expression of the stem cell inducer WUSCHEL independently of photosynthesis and that this likely involves inter-regional cytokinin signaling. Metabolic signals, on the other hand, are transduced to the meristem through activation of the TARGET OF RAPAMYCIN (TOR) kinase. Surprisingly, TOR is also required for light signal dependent stem cell activation. Thus, the TOR kinase acts as a central integrator of light and metabolic signals and a key regulator of stem cell activation at the shoot apex. PMID:27400267

  3. Themis1 enhances T cell receptor signaling during thymocyte development by promoting Vav1 activity and Grb2 stability.

    PubMed

    Zvezdova, Ekaterina; Mikolajczak, Judith; Garreau, Anne; Marcellin, Marlène; Rigal, Lise; Lee, Jan; Choi, Seeyoung; Blaize, Gaëtan; Argenty, Jérémy; Familiades, Julien; Li, Liqi; Gonzalez de Peredo, Anne; Burlet-Schiltz, Odile; Love, Paul E; Lesourne, Renaud

    2016-01-01

    The T cell signaling protein Themis1 is essential for the positive and negative selection of thymocytes in the thymus. Although the developmental defect that results from the loss of Themis1 suggests that it enhances T cell receptor (TCR) signaling, Themis1 also recruits Src homology 2 domain-containing phosphatase-1 (SHP-1) to the vicinity of TCR signaling complexes, suggesting that it has an inhibitory role in TCR signaling. We used TCR signaling reporter mice and quantitative proteomics to explore the role of Themis1 in developing T cells. We found that Themis1 acted mostly as a positive regulator of TCR signaling in vivo when receptors were activated by positively selecting ligands. Proteomic analysis of the Themis1 interactome identified SHP-1, the TCR-associated adaptor protein Grb2, and the guanine nucleotide exchange factor Vav1 as the principal interacting partners of Themis1 in isolated mouse thymocytes. Analysis of TCR signaling in Themis1-deficient and Themis1-overexpressing mouse thymocytes demonstrated that Themis1 promoted Vav1 activity both in vitro and in vivo. The reduced activity of Vav1 and the impaired T cell development in Themis1(-/-) mice were due in part to increased degradation of Grb2, which suggests that Themis1 is required to maintain the steady-state abundance of Grb2 in thymocytes. Together, these data suggest that Themis1 acts as a positive regulator of TCR signaling in developing T cells, and identify a mechanism by which Themis1 regulates thymic selection. PMID:27188442

  4. Modular activation of Rho1 by GPCR signalling imparts polarized myosin II activation during morphogenesis.

    PubMed

    Kerridge, Stephen; Munjal, Akankshi; Philippe, Jean-Marc; Jha, Ankita; de las Bayonas, Alain Garcia; Saurin, Andrew J; Lecuit, Thomas

    2016-03-01

    Polarized cell shape changes during tissue morphogenesis arise by controlling the subcellular distribution of myosin II. For instance, during Drosophila melanogaster gastrulation, apical constriction and cell intercalation are mediated by medial-apical myosin II pulses that power deformations, and polarized accumulation of myosin II that stabilizes these deformations. It remains unclear how tissue-specific factors control different patterns of myosin II activation and the ratchet-like myosin II dynamics. Here we report the function of a common pathway comprising the heterotrimeric G proteins Gα12/13, Gβ13F and Gγ1 in activating and polarizing myosin II during Drosophila gastrulation. Gα12/13 and the Gβ13F/γ1 complex constitute distinct signalling modules, which regulate myosin II dynamics medial-apically and/or junctionally in a tissue-dependent manner. We identify a ubiquitously expressed GPCR called Smog required for cell intercalation and apical constriction. Smog functions with other GPCRs to quantitatively control G proteins, resulting in stepwise activation of myosin II and irreversible cell shape changes. We propose that GPCR and G proteins constitute a general pathway for controlling actomyosin contractility in epithelia and that the activity of this pathway is polarized by tissue-specific regulators. PMID:26780298

  5. Angiogenic activity of sesamin through the activation of multiple signal pathways

    SciTech Connect

    Chung, Byung-Hee; Lee, Jung Joon; Kim, Jong-Dai; Jeoung, Dooil; Lee, Hansoo; Choe, Jongseon; Ha, Kwon-Soo; Kwon, Young-Geun; Kim, Young-Myeong

    2010-01-01

    The natural product sesamin has been known to act as a potent antioxidant and prevent endothelial dysfunction. We here found that sesamin increased in vitro angiogenic processes, such as endothelial cell proliferation, migration, and tube formation, as well as neovascularization in an animal model. This compound elicited the activation of multiple angiogenic signal modulators, such as ERK, Akt, endothelial nitric oxide synthase (eNOS), NO production, FAK, and p38 MAPK, but not Src. The MEK inhibitor PD98059 and the PI3K inhibitor Wortmannin specifically inhibited sesamin-induced activation of the ERK and Akt/eNOS pathways. These inhibitors reduced angiogenic events, with high specificity for MEK/ERK-dependent cell proliferation and migration and PI3K/Akt-mediated tube formation. Moreover, inhibition of p38 MAPK effectively inhibited sesamin-induced cell migration. The angiogenic activity of sesamin was not associated with VEGF expression. Furthermore, this compound did not induce vascular permeability and upregulated ICAM-1 and VCAM-1 expression, which are hallmarks of vascular inflammation. These results suggest that sesamin stimulates angiogenesis in vitro and in vivo through the activation of MEK/ERK-, PI3K/Akt/eNOS-, p125{sup FAK}-, and p38 MAPK-dependent pathways, without increasing vascular inflammation, and may be used for treating ischemic diseases and tissue regeneration.

  6. Activation of MEK/ERK Signaling by PACAP in Guinea Pig Cardiac Neurons.

    PubMed

    Clason, Todd A; Girard, Beatrice M; May, Victor; Parsons, Rodney L

    2016-06-01

    Pituitary adenylate cyclase-activating polypeptide (PACAP) signaling can increase guinea pig cardiac neuron excitability in part through extracellular signal-regulated kinase (ERK) activation. The present study examined the PACAP receptors and signaling cascades that stimulate guinea pig cardiac neuron ERK signaling using confocal microscopy to quantify PACAP-induced neuronal phosphorylated ERK (pERK) immunoreactivity. PACAP and maxadilan, but not vasoactive intestinal polypeptide (VIP), increased cardiac neuron pERK, implicating primary roles for PACAP-selective PAC1 receptor (Adcyap1r1) signaling rather than VPAC receptors (Vipr1 and Vipr2) in the generation of cardiac neuron pERK. The adenylyl cyclase (AC) activator forskolin, but not the protein kinase C (PKC) activator phorbol myristate acetate (PMA), increased pERK. Also, Bim1 did not blunt PACAP activation of pERK. Together, the results suggest PAC1 receptor signal transduction via Gs/adenylyl cyclase (AC)/cAMP rather than Gq/phospholipase C (PLC) generated neuronal pERK. Activator and inhibitor studies suggested that the PACAP-mediated pERK activation was PKA-dependent rather than an exchange protein directly activated by a cAMP (EPAC), PKA-independent mechanism. The PACAP-induced pERK was inhibited by the clathrin inhibitor Pitstop2 to block receptor internalization and endosomal signaling. We propose that the PACAP-mediated MEK/ERK activation in cardiac neurons involves both AC/cAMP/PKA signaling and PAC1 receptor internalization/activation of signaling endosomes. PMID:27194157

  7. Asymmetric activation of Dll4-Notch signaling by Foxn4 and proneural factors activates BMP/TGFβ signaling to specify V2b interneurons in the spinal cord

    PubMed Central

    Misra, Kamana; Luo, Huijun; Li, Shengguo; Matise, Michael; Xiang, Mengqing

    2014-01-01

    During development of the ventral spinal cord, the V2 interneurons emerge from p2 progenitors and diversify into two major subtypes, V2a and V2b, that play key roles in locomotor coordination. Dll4-mediated Notch activation in a subset of p2 precursors constitutes the crucial first step towards generating neuronal diversity in this domain. The mechanism behind the asymmetric Notch activation and downstream signaling events are, however, unknown at present. We show here that the Ascl1 and Neurog basic helix-loop-helix (bHLH) proneural factors are expressed in a mosaic pattern in p2 progenitors and that Foxn4 is required for setting and maintaining this expression mosaic. By binding directly to a conserved Dll4 enhancer, Foxn4 and Ascl1 activate Dll4 expression, whereas Neurog proteins prevent this effect, thereby resulting in asymmetric activation of Dll4 expression in V2 precursors expressing different combinations of proneural and Foxn4 transcription factors. Lineage tracing using the Cre-LoxP system reveals selective expression of Dll4 in V2a precursors, whereas Dll4 expression is initially excluded from V2b precursors. We provide evidence that BMP/TGFβ signaling is activated in V2b precursors and that Dll4-mediated Notch signaling is responsible for this activation. Using a gain-of-function approach and by inhibiting BMP/TGFβ signal transduction with pathway antagonists and RNAi knockdown, we further demonstrate that BMP/TGFβ signaling is both necessary and sufficient for V2b fate specification. Our data together thus suggest that the mosaic expression of Foxn4 and proneural factors may serve as the trigger to initiate asymmetric Dll4-Notch and subsequent BMP/TGFβ signaling events required for neuronal diversity in the V2 domain. PMID:24257627

  8. Characterizing and differentiating task-based and resting state fMRI signals via two-stage sparse representations.

    PubMed

    Zhang, Shu; Li, Xiang; Lv, Jinglei; Jiang, Xi; Guo, Lei; Liu, Tianming

    2016-03-01

    A relatively underexplored question in fMRI is whether there are intrinsic differences in terms of signal composition patterns that can effectively characterize and differentiate task-based or resting state fMRI (tfMRI or rsfMRI) signals. In this paper, we propose a novel two-stage sparse representation framework to examine the fundamental difference between tfMRI and rsfMRI signals. Specifically, in the first stage, the whole-brain tfMRI or rsfMRI signals of each subject were composed into a big data matrix, which was then factorized into a subject-specific dictionary matrix and a weight coefficient matrix for sparse representation. In the second stage, all of the dictionary matrices from both tfMRI/rsfMRI data across multiple subjects were composed into another big data-matrix, which was further sparsely represented by a cross-subjects common dictionary and a weight matrix. This framework has been applied on the recently publicly released Human Connectome Project (HCP) fMRI data and experimental results revealed that there are distinctive and descriptive atoms in the cross-subjects common dictionary that can effectively characterize and differentiate tfMRI and rsfMRI signals, achieving 100% classification accuracy. Moreover, our methods and results can be meaningfully interpreted, e.g., the well-known default mode network (DMN) activities can be recovered from the very noisy and heterogeneous aggregated big-data of tfMRI and rsfMRI signals across all subjects in HCP Q1 release. PMID:25732072

  9. 34 CFR 300.704 - State-level activities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 34 Education 2 2012-07-01 2012-07-01 false State-level activities. 300.704 Section 300.704... Allotments, Grants, and Use of Funds § 300.704 State-level activities. (a) State administration. (1) For the... may be used for the administration of Part C of the Act, if the SEA is the lead agency for the...

  10. 34 CFR 300.704 - State-level activities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 34 Education 2 2011-07-01 2010-07-01 true State-level activities. 300.704 Section 300.704... Allotments, Grants, and Use of Funds § 300.704 State-level activities. (a) State administration. (1) For the... may be used for the administration of Part C of the Act, if the SEA is the lead agency for the...

  11. Choline-releasing glycerophosphodiesterase EDI3 links the tumor metabolome to signaling network activities.

    PubMed

    Marchan, Rosemarie; Lesjak, Michaela S; Stewart, Joanna D; Winter, Roland; Seeliger, Janine; Hengstler, Jan G

    2012-12-15

    Recently, EDI3 was identified as a key factor for choline metabolism that controls tumor cell migration and is associated with metastasis in endometrial carcinomas. EDI3 cleaves glycerophosphocholine (GPC) to form choline and glycerol-3-phosphate (G3P). Choline is then further metabolized to phosphatidylcholine (PtdC), the major lipid in membranes and a key player in membrane-mediated cell signaling. The second product, G3P, is a precursor molecule for several lipids with central roles in signaling, for example lysophosphatidic acid (LPA), phosphatidic acid (PA) and diacylglycerol (DAG). LPA activates intracellular signaling pathways by binding to specific LPA receptors, including membrane-bound G protein-coupled receptors and the intracellular nuclear receptor, PPARγ. Conversely, PA and DAG mediate signaling by acting as lipid anchors that bind and activate several signaling proteins. For example, binding of GTPases and PKC to PA and DAG, respectively, increases the activation of signaling networks, mediating processes such as migration, adhesion, proliferation or anti-apoptosis-all relevant for tumor development. We present a concept by which EDI3 either directly generates signaling molecules or provides "membrane anchors" for downstream signaling factors. As a result, EDI3 links choline metabolism to signaling activities resulting in a more malignant phenotype. PMID:23114620

  12. Signal transduction controls heterogeneous NF-κB dynamics and target gene expression through cytokine-specific refractory states

    PubMed Central

    Adamson, Antony; Boddington, Christopher; Downton, Polly; Rowe, William; Bagnall, James; Lam, Connie; Maya-Mendoza, Apolinar; Schmidt, Lorraine; Harper, Claire V.; Spiller, David G.; Rand, David A.; Jackson, Dean A.; White, Michael R. H.; Paszek, Pawel

    2016-01-01

    Cells respond dynamically to pulsatile cytokine stimulation. Here we report that single, or well-spaced pulses of TNFα (>100 min apart) give a high probability of NF-κB activation. However, fewer cells respond to shorter pulse intervals (<100 min) suggesting a heterogeneous refractory state. This refractory state is established in the signal transduction network downstream of TNFR and upstream of IKK, and depends on the level of the NF-κB system negative feedback protein A20. If a second pulse within the refractory phase is IL-1β instead of TNFα, all of the cells respond. This suggests a mechanism by which two cytokines can synergistically activate an inflammatory response. Gene expression analyses show strong correlation between the cellular dynamic response and NF-κB-dependent target gene activation. These data suggest that refractory states in the NF-κB system constitute an inherent design motif of the inflammatory response and we suggest that this may avoid harmful homogenous cellular activation. PMID:27381163

  13. Feeding state-dependent regulation of developmental plasticity via CaMKI and neuroendocrine signaling

    PubMed Central

    Neal, Scott J; Takeishi, Asuka; O'Donnell, Michael P; Park, JiSoo; Hong, Myeongjin; Butcher, Rebecca A; Kim, Kyuhyung; Sengupta, Piali

    2015-01-01

    Information about nutrient availability is assessed via largely unknown mechanisms to drive developmental decisions, including the choice of Caenorhabditis elegans larvae to enter into the reproductive cycle or the dauer stage. In this study, we show that CMK-1 CaMKI regulates the dauer decision as a function of feeding state. CMK-1 acts cell-autonomously in the ASI, and non cell-autonomously in the AWC, sensory neurons to regulate expression of the growth promoting daf-7 TGF-β and daf-28 insulin-like peptide (ILP) genes, respectively. Feeding state regulates dynamic subcellular localization of CMK-1, and CMK-1-dependent expression of anti-dauer ILP genes, in AWC. A food-regulated balance between anti-dauer ILP signals from AWC and pro-dauer signals regulates neuroendocrine signaling and dauer entry; disruption of this balance in cmk-1 mutants drives inappropriate dauer formation under well-fed conditions. These results identify mechanisms by which nutrient information is integrated in a small neuronal network to modulate neuroendocrine signaling and developmental plasticity. DOI: http://dx.doi.org/10.7554/eLife.10110.001 PMID:26335407

  14. Enhanced magnetic flux density mapping using coherent steady state equilibrium signal in MREIT

    NASA Astrophysics Data System (ADS)

    Jeong, Woo Chul; Lee, Mun Bae; Sajib, Saurav Z. K.; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2016-03-01

    Measuring the z-component of magnetic flux density B = (Bx, By, Bz) induced by transversally injected current, magnetic resonance electrical impedance tomography (MREIT) aims to visualize electrical property (current density and/or conductivity distribution) in a three-dimensional imaging object. For practical implementations of MREIT technique, it is critical to reduce injection of current pulse within safety requirements. With the goal of minimizing the noise level in measured Bz data, we propose a new method to enhance the measure Bz data using steady-state coherent gradient multi-echo (SSC-GME) MR pulse sequence combining with injection current nonlinear encoding (ICNE) method in MREIT, where the ICNE technique injects current during a readout gradient to maximize the signal intensity of phase signal including Bz. The total phase offset in SSC-GME includes additional magnetic flux density due to the injected current, which is different from the phase signal for the conventional spoiled MR pulse sequence. We decompose the magnetization precession phase from the total phase offset including Bz and optimize Bz data using the steady-state equilibrium signal. Results from a real phantom experiment including different kinds of anomalies demonstrated that the proposed method enhanced Bz comparing to a conventional spoiled pulse sequence.

  15. Imaging Odor-Evoked Activities in the Mouse Olfactory Bulb using Optical Reflectance and Autofluorescence Signals

    PubMed Central

    Chery, Romain; L'Heureux, Barbara; Bendahmane, Mounir; Renaud, Rémi; Martin, Claire; Pain, Frédéric; Gurden, Hirac

    2011-01-01

    In the brain, sensory stimulation activates distributed populations of neurons among functional modules which participate to the coding of the stimulus. Functional optical imaging techniques are advantageous to visualize the activation of these modules in sensory cortices with high spatial resolution. In this context, endogenous optical signals that arise from molecular mechanisms linked to neuroenergetics are valuable sources of contrast to record spatial maps of sensory stimuli over wide fields in the rodent brain. Here, we present two techniques based on changes of endogenous optical properties of the brain tissue during activation. First the intrinsic optical signals (IOS) are produced by a local alteration in red light reflectance due to: (i) absorption by changes in blood oxygenation level and blood volume (ii) photon scattering. The use of in vivo IOS to record spatial maps started in the mid 1980's with the observation of optical maps of whisker barrels in the rat and the orientation columns in the cat visual cortex1. IOS imaging of the surface of the rodent main olfactory bulb (OB) in response to odorants was later demonstrated by Larry Katz's group2. The second approach relies on flavoprotein autofluorescence signals (FAS) due to changes in the redox state of these mitochondrial metabolic intermediates. More precisely, the technique is based on the green fluorescence due to oxidized state of flavoproteins when the tissue is excited with blue light. Although such signals were probably among the first fluorescent molecules recorded for the study of brain activity by the pioneer studies of Britton Chances and colleagues3, it was not until recently that they have been used for mapping of brain activation in vivo. FAS imaging was first applied to the somatosensory cortex in rodents in response to hindpaw stimulation by Katsuei Shibuki's group4. The olfactory system is of central importance for the survival of the vast majority of living species because it

  16. Suppression of Epithelial Signal Transducer and Activator of Transcription 1 Activation by Extracts of Aspergillus fumigatus

    PubMed Central

    Bhushan, Bharat; Homma, Tetsuya; Norton, James E.; Sha, Quan; Siebert, Jason; Gupta, Dave S.; Schroeder, James W.

    2015-01-01

    Aspergillus fumigatus (AF) is often pathogenic in immune-deficient individuals and can cause life-threatening infections such as invasive aspergillosis. The pulmonary epithelial response to AF infection and the signaling pathways associated with it have not been completely studied. BEAS-2B cells or primary human bronchial epithelial cells were exposed to extracts of AF and challenged with IFN-β or the Toll-like receptor 3 agonist double-stranded RNA (dsRNA). Cytokine release (B-cell activating factor of the TNF family [BAFF], IFN-γ–induced protein-10 [IP-10], etc.) was assessed. AF extract was separated into low-molecular-weight (LMW) and high-molecular-weight (HMW) fractions using ultra 4 centrifugal force filters to characterize the activity. Real-time PCR was performed with a TaqMan method, and protein estimation was performed using ELISA techniques. Western blot was performed to assess phosphorylation of signal transducer and activator of transcription 1 (STAT1). IFN-β and dsRNA induced messenger RNA (mRNA) expression of BAFF (350- and 452-fold, respectively [n = 3]) and IP-10 (1,081- and 3,044-fold, respectively [n = 3]) in BEAS-2B cells. When cells were pretreated with AF extract for 1 hour and then stimulated with IFN-β or dsRNA for 6 hours, induction of BAFF and IP-10 mRNA was strongly suppressed relative to levels produced by IFN-β and dsRNA alone. When compared with control, soluble BAFF and IP-10 protein levels were maximally suppressed in dsRNA-stimulated wells treated with 1:320 wt/vol AF extract (P < 0.005). Upon molecular size fractionation, a LMW fraction of AF extract had no measurable suppressive effect on IP-10 mRNA expression. However, a HMW fraction of the AF extract significantly suppressed IP-10 expression in BEAS-2B cells that were stimulated with dsRNA or IFN-β. When BEAS-2B cells were pretreated with AF extract and then stimulated with IFN-β, reduced levels of pSTAT1 were observed, with maximum suppression at 4 and 6

  17. Suppression of epithelial signal transducer and activator of transcription 1 activation by extracts of Aspergillus fumigatus.

    PubMed

    Bhushan, Bharat; Homma, Tetsuya; Norton, James E; Sha, Quan; Siebert, Jason; Gupta, Dave S; Schroeder, James W; Schleimer, Robert P

    2015-07-01

    Aspergillus fumigatus (AF) is often pathogenic in immune-deficient individuals and can cause life-threatening infections such as invasive aspergillosis. The pulmonary epithelial response to AF infection and the signaling pathways associated with it have not been completely studied. BEAS-2B cells or primary human bronchial epithelial cells were exposed to extracts of AF and challenged with IFN-β or the Toll-like receptor 3 agonist double-stranded RNA (dsRNA). Cytokine release (B-cell activating factor of the TNF family [BAFF], IFN-γ-induced protein-10 [IP-10], etc.) was assessed. AF extract was separated into low-molecular-weight (LMW) and high-molecular-weight (HMW) fractions using ultra 4 centrifugal force filters to characterize the activity. Real-time PCR was performed with a TaqMan method, and protein estimation was performed using ELISA techniques. Western blot was performed to assess phosphorylation of signal transducer and activator of transcription 1 (STAT1). IFN-β and dsRNA induced messenger RNA (mRNA) expression of BAFF (350- and 452-fold, respectively [n = 3]) and IP-10 (1,081- and 3,044-fold, respectively [n = 3]) in BEAS-2B cells. When cells were pretreated with AF extract for 1 hour and then stimulated with IFN-β or dsRNA for 6 hours, induction of BAFF and IP-10 mRNA was strongly suppressed relative to levels produced by IFN-β and dsRNA alone. When compared with control, soluble BAFF and IP-10 protein levels were maximally suppressed in dsRNA-stimulated wells treated with 1:320 wt/vol AF extract (P < 0.005). Upon molecular size fractionation, a LMW fraction of AF extract had no measurable suppressive effect on IP-10 mRNA expression. However, a HMW fraction of the AF extract significantly suppressed IP-10 expression in BEAS-2B cells that were stimulated with dsRNA or IFN-β. When BEAS-2B cells were pretreated with AF extract and then stimulated with IFN-β, reduced levels of pSTAT1 were observed, with maximum suppression at 4 and 6

  18. 12 CFR 362.3 - Activities of insured State banks.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 5 2013-01-01 2013-01-01 false Activities of insured State banks. 362.3 Section 362.3 Banks and Banking FEDERAL DEPOSIT INSURANCE CORPORATION REGULATIONS AND STATEMENTS OF GENERAL POLICY ACTIVITIES OF INSURED STATE BANKS AND INSURED SAVINGS ASSOCIATIONS Activities of...

  19. 12 CFR 362.3 - Activities of insured State banks.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 4 2010-01-01 2010-01-01 false Activities of insured State banks. 362.3 Section 362.3 Banks and Banking FEDERAL DEPOSIT INSURANCE CORPORATION REGULATIONS AND STATEMENTS OF GENERAL POLICY ACTIVITIES OF INSURED STATE BANKS AND INSURED SAVINGS ASSOCIATIONS Activities of...

  20. No signaling and strong subadditivity condition for tomographic q-entropy of single qudit states

    NASA Astrophysics Data System (ADS)

    Chernega, Vladimir N.; Man'ko, Olga V.

    2015-06-01

    The single-qudit state tomograms are shown to have the no-signaling property. The known and new entropic and information inequalities for Shannon, von Neumann, and q-entropies of the composite and noncomposite systems characterizing correlations in these systems are discussed. The spin tomographic probability distributions determining the single qudit states are demonstrated to satisfy the strong subadditivity condition for Tsallis q-entropy. Examples of the new entropic inequalities for q-entropy are considered for qudits with j=5/2, j=7/2.

  1. Validity Evidence for the State Mindfulness Scale for Physical Activity

    ERIC Educational Resources Information Center

    Cox, Anne E.; Ullrich-French, Sarah; French, Brian F.

    2016-01-01

    Being attentive to and aware of one's experiences in the present moment with qualities of acceptance and openness reflects the state of mindfulness. Positive associations exist between state mindfulness and state autonomous motivation for everyday activities. Though this suggests that state mindfulness links with adaptive motivational experiences,…

  2. Dynamic characteristics of two-state lasing quantum dot lasers under large signal modulation

    SciTech Connect

    Lv, Zun-Ren; Ji, Hai-Ming Luo, Shuai; Gao, Feng; Xu, Feng; Yang, Tao; Xiao, De-Hang

    2015-10-15

    Large signal modulation characteristics of the simultaneous ground-state (GS) and excited-state (ES) lasing quantum dot lasers are theoretically investigated. Relaxation oscillations of ‘0 → 1’ and ‘1 → 0’ in the GS lasing region (Region I), the transition region from GS lasing to two-state lasing (Region II) and the two-state lasing region (Region III) are compared and analyzed. It is found that the overshooting power and settling time in both Regions I and III decrease as the bias current increases. However, there exist abnormal behaviors of the overshooting power and settling time in Region II owing to the occurrence of ES lasing, which lead to fuzzy eye diagrams of the GS and ES lasing. Moreover, the ES lasing in Region III possesses much better eye diagrams because of its shorter settling time and smaller overshooting power over the GS lasing in Region I.

  3. Extracellular signal-regulated kinase 1/2 signalling in SLE T cells is influenced by oestrogen and disease activity.

    PubMed

    Gorjestani, S; Rider, V; Kimler, B F; Greenwell, C; Abdou, N I

    2008-06-01

    Systemic lupus erythematosus (SLE) is an autoimmune disease that occurs primarily in women of reproductive age. The disease is characterized by exaggerated T-cell activity and abnormal T-cell signalling. The mitogen-activated protein kinase (MAPK) pathway is involved in the maintenance of T-cell tolerance that fails in patients with SLE. Oestrogen is a female sex hormone that binds to nuclear receptors and alters the rate of gene transcription. Oestrogen can also act through the plasma membrane and rapidly stimulate second messengers including calcium flux and kinase activation. In this study, we investigated whether oestrogen influences the activation of MAPK signalling through the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) in activated SLE T cells. SLE and control T cells were cultured in serum-free medium without and with oestradiol (10(-7) M) for 18 h. The T cells were activated with phorbol 12 myristate 13-acetate and ionomycin for various time points (0-60 min), and the amount of phosphorylated ERK1/2 was measured by immunoblotting. There were no differences in ERK1/2 phosphorylation between SLE and control T cells at 5 and 15 min after the activation stimulus. However, comparison between the amount of phosphorylated ERK1/2 in SLE T cells from the same patients cultured without and with oestradiol showed a significant oestrogen-dependent suppression (P=0.48) of ERK1/2 in patients with inactive/mild systemic lupus erythematosus disease activity index (SLEDAI) (0-2) compared with patients with moderate (4-6) or active (8-12) SLEDAI scores. These results suggest that the suppression of MAPK through ERK1/2 phosphorylation is sensitive to oestradiol in patients with inactive or mild disease, but the sensitivity is not maintained when disease activity increases. Furthermore, studies are now necessary to understand the mechanisms by which oestrogen influences MAPK activation in SLE T cells. PMID:18539708

  4. Asphyxia-activated corticocardiac signaling accelerates onset of cardiac arrest

    PubMed Central

    Li, Duan; Mabrouk, Omar S.; Liu, Tiecheng; Tian, Fangyun; Xu, Gang; Rengifo, Santiago; Choi, Sarah J.; Mathur, Abhay; Crooks, Charles P.; Kennedy, Robert T.; Wang, Michael M.; Ghanbari, Hamid; Borjigin, Jimo

    2015-01-01

    The mechanism by which the healthy heart and brain die rapidly in the absence of oxygen is not well understood. We performed continuous electrocardiography and electroencephalography in rats undergoing experimental asphyxia and analyzed cortical release of core neurotransmitters, changes in brain and heart electrical activity, and brain–heart connectivity. Asphyxia stimulates a robust and sustained increase of functional and effective cortical connectivity, an immediate increase in cortical release of a large set of neurotransmitters, and a delayed activation of corticocardiac functional and effective connectivity that persists until the onset of ventricular fibrillation. Blocking the brain’s autonomic outflow significantly delayed terminal ventricular fibrillation and lengthened the duration of detectable cortical activities despite the continued absence of oxygen. These results demonstrate that asphyxia activates a brainstorm, which accelerates premature death of the heart and the brain. PMID:25848007

  5. Physical coupling of activation and derepression activities to maintain an active transcriptional state at FLC.

    PubMed

    Yang, Hongchun; Howard, Martin; Dean, Caroline

    2016-08-16

    Establishment and maintenance of gene expression states is central to development and differentiation. Transcriptional and epigenetic mechanisms interconnect in poorly understood ways to determine these states. We explore these mechanisms through dissection of the regulation of Arabidopsis thaliana FLOWERING LOCUS C (FLC). FLC can be present in a transcriptionally active state marked by H3K36me3 or a silent state marked by H3K27me3. Here, we investigate the trans factors modifying these opposing histone states and find a physical coupling in vivo between the H3K36 methyltransferase, SDG8, and the H3K27me3 demethylase, ELF6. Previous modeling has predicted this coupling would exist as it facilitates bistability of opposing histone states. We also find association of SDG8 with the transcription machinery, namely RNA polymerase II and the PAF1 complex. Delivery of the active histone modifications is therefore likely to be through transcription at the locus. SDG8 and ELF6 were found to influence the localization of each other on FLC chromatin, showing the functional importance of the interaction. In addition, both influenced accumulation of the associated H3K27me3 and H3K36me3 histone modifications at FLC We propose the physical coupling of activation and derepression activities coordinates transcriptional activity and prevents ectopic silencing. PMID:27482092

  6. Physical coupling of activation and derepression activities to maintain an active transcriptional state at FLC

    PubMed Central

    Yang, Hongchun; Howard, Martin; Dean, Caroline

    2016-01-01

    Establishment and maintenance of gene expression states is central to development and differentiation. Transcriptional and epigenetic mechanisms interconnect in poorly understood ways to determine these states. We explore these mechanisms through dissection of the regulation of Arabidopsis thaliana FLOWERING LOCUS C (FLC). FLC can be present in a transcriptionally active state marked by H3K36me3 or a silent state marked by H3K27me3. Here, we investigate the trans factors modifying these opposing histone states and find a physical coupling in vivo between the H3K36 methyltransferase, SDG8, and the H3K27me3 demethylase, ELF6. Previous modeling has predicted this coupling would exist as it facilitates bistability of opposing histone states. We also find association of SDG8 with the transcription machinery, namely RNA polymerase II and the PAF1 complex. Delivery of the active histone modifications is therefore likely to be through transcription at the locus. SDG8 and ELF6 were found to influence the localization of each other on FLC chromatin, showing the functional importance of the interaction. In addition, both influenced accumulation of the associated H3K27me3 and H3K36me3 histone modifications at FLC. We propose the physical coupling of activation and derepression activities coordinates transcriptional activity and prevents ectopic silencing. PMID:27482092

  7. Efficient Activation of Apoptotic Signaling during Mitotic Arrest with AK301

    PubMed Central

    Bleiler, Marina; Yeagley, Michelle; Wright, Dennis; Giardina, Charles

    2016-01-01

    Mitotic inhibitors are widely utilized chemotherapeutic agents that take advantage of mitotic defects in cancer cells. We have identified a novel class of piperazine-based mitotic inhibitors, of which AK301 is the most potent derivative identified to date (EC50 < 200 nM). Colon cancer cells arrested in mitosis with AK301 readily underwent a p53-dependent apoptosis following compound withdrawal and arrest release. This apoptotic response was significantly higher for AK301 than for other mitotic inhibitors tested (colchicine, vincristine, and BI 2536). AK301-treated cells exhibited a robust mitosis-associated DNA damage response, including ATM activation, γH2AX phosphorylation and p53 stabilization. The association between mitotic signaling and the DNA damage response was supported by the finding that Aurora B inhibition reduced the level of γH2AX staining. Confocal imaging of AK301-treated cells revealed multiple γ-tubulin microtubule organizing centers attached to microtubules, but with limited centrosome migration, raising the possibility that aberrant microtubule pulling may underlie DNA breakage. AK301 selectively targeted APC-mutant colonocytes and promoted TNF-induced apoptosis in p53-mutant colon cancer cells. Our findings indicate that AK301 induces a mitotic arrest state with a highly active DNA damage response. Together with a reversible arrest state, AK301 is a potent promoter of a mitosis-to-apoptosis transition that can target cancer cells with mitotic defects. PMID:27097159

  8. Alternative splicing of MALT1 controls signalling and activation of CD4+ T cells

    PubMed Central

    Meininger, Isabel; Griesbach, Richard A.; Hu, Desheng; Gehring, Torben; Seeholzer, Thomas; Bertossi, Arianna; Kranich, Jan; Oeckinghaus, Andrea; Eitelhuber, Andrea C.; Greczmiel, Ute; Gewies, Andreas; Schmidt-Supprian, Marc; Ruland, Jürgen; Brocker, Thomas; Heissmeyer, Vigo; Heyd, Florian; Krappmann, Daniel

    2016-01-01

    MALT1 channels proximal T-cell receptor (TCR) signalling to downstream signalling pathways. With MALT1A and MALT1B two conserved splice variants exist and we demonstrate here that MALT1 alternative splicing supports optimal T-cell activation. Inclusion of exon7 in MALT1A facilitates the recruitment of TRAF6, which augments MALT1 scaffolding function, but not protease activity. Naive CD4+ T cells express almost exclusively MALT1B and MALT1A expression is induced by TCR stimulation. We identify hnRNP U as a suppressor of exon7 inclusion. Whereas selective depletion of MALT1A impairs T-cell signalling and activation, downregulation of hnRNP U enhances MALT1A expression and T-cell activation. Thus, TCR-induced alternative splicing augments MALT1 scaffolding to enhance downstream signalling and to promote optimal T-cell activation. PMID:27068814

  9. Shuttle extravehicular activity signal processor pulse amplitude modulation decommutator

    NASA Technical Reports Server (NTRS)

    Noble, D. E.; Conrad, W. M.

    1974-01-01

    To provide data with long-term stability and accuracy, the pulse amplitude modulation (PAM) decommutator was synchronized to the PAM-return to zero wavetrain, and each channel was sampled with a common sample and hold circuit and digitized sequentially. The digital value of each channel was then scaled by the digital value of the calibration channels. The corrected digital value of each channel was stored for one complete frame and then transferred to the multiplexer-demultiplexer at a high rate in one block of serial digital data. A test model was built to demonstrate this design approach taken for the PAM decom and performance data was provided. The accuracies obtained with various signal to noise ratios are shown.

  10. Pleiotropic patterning response to activation of Shh signaling in the limb Apical Ectodermal Ridge

    PubMed Central

    Wang, Chi-Kuang Leo; Tsugane, Mizuyo H.; Scranton, Victoria; Kosher, Robert A.; Pierro, Louis J.; Upholt, William B.; Dealy, Caroline N.

    2012-01-01

    Sonic hedgehog (Shh) signaling in the limb plays a central role in coordination of limb patterning and outgrowth. Shh expression in the limb is limited to the cells of the Zone of Polarizing Activity (ZPA), located in posterior limb bud mesoderm. Shh is not expressed by limb ectoderm or AER, but recent studies suggest a role for AER-Shh signaling in limb patterning. Here, we have examined the effects of activation of Shh signaling in the AER. We find that targeted expression of Shh in the AER activates constitutive Shh signaling throughout the AER and subjacent limb mesoderm, and causes a range of limb patterning defects with progressive severity from mild polydactyly, to polysyndactyly with proximal defects, to severe oligodactyly with phocomelia and partial limb ventralization. Our studies emphasize the importance of control of the timing, level and location of Shh pathway signaling for limb AP, PD and DV patterning. PMID:21465622

  11. GPCR-like signaling mediated by smoothened contributes to acquired chemoresistance through activating Gli

    PubMed Central

    2014-01-01

    Background Smoothened (Smo), which possesses a structural similarity with classic G-protein coupled receptors (GPCR), is the most important molecular target in Hedgehog (Hh) signaling system for developing anticancer drugs; however, whether Smo may transmit GPCR-like signaling to activate the canonical transcriptional factor Gli of Hh signaling system and consequently to be involved in the Gli-dependent biological events remains controversial. Results In this study, using the acquired chemoresistant cancer cell lines and their respective parental cells, we found that Smo may activate Gli through Gαi, Gβγ-JNK signaling axis, thereby promoting the Gli-dependent acquired chemoresistance. These observations were further complementarily strengthened by data obtained from chemosensitive cancer cells with artificially elevated Hh pathway activity. Conclusions Hence, our data demonstrate that GPCR-like signaling mediated by Smo contributes to the acquired chemoresistance through activating the canonical Hh transcriptional factor Gli; therefore improving our knowledge of the nature of the signal transduction of Smo and the molecular mechanisms responsible for the acquired chemoresistance maintained by Hh pathway. Moreover, our data that JNK after activated by Smo-Gβγ signaling axis may stimulate the Gli activity and consequently promotes acquired chemoresistance expose a promising and potential target for developing anti-cancer drugs aimed at Hh pathway and for combating the acquired resistance raised by using of anti-cancer drugs targeting Smo. PMID:24393163

  12. Discovery of Novel Small Molecule Activators of β-Catenin Signaling

    PubMed Central

    Verkaar, Folkert; van der Stelt, Mario; Blankesteijn, W. Matthijs; van der Doelen, Antoon A.; Zaman, Guido J. R.

    2011-01-01

    Wnt/β-catenin signaling plays a major role in embryonic development and adult stem cell maintenance. Reduced activation of the Wnt/β-catenin pathway underlies neurodegenerative disorders and aberrations in bone formation. Screening of a small molecule compound library with a β-galactosidase fragment complementation assay measuring β-catenin nuclear entry revealed bona fide activators of β-catenin signaling. The compounds stabilized cytoplasmic β-catenin and activated β–catenin-dependent reporter gene activity. Although the mechanism through which the compounds activate β-catenin signaling has yet to be determined, several key regulators of Wnt/β-catenin signaling, including glycogen synthase kinase 3 and Frizzled receptors, were excluded as the molecular target. The compounds displayed remarkable selectivity, as they only induced β-catenin signaling in a human osteosarcoma U2OS cell line and not in a variety of other cell lines examined. Our data indicate that differences in cellular Wnt/β-catenin signaling machinery can be exploited to identify cell type-specific activators of Wnt/β-catenin signaling. PMID:21559429

  13. Lipopolysaccharide activated TLR4/NF-κB signaling pathway of fibroblasts from uterine fibroids.

    PubMed

    Guo, Jing; Zheng, Lihua; Chen, Li; Luo, Ning; Yang, Weihong; Qu, Xiaoyan; Liu, Mingmin; Cheng, Zhongping

    2015-01-01

    Uterine fibroids (UF) are the most common benign tumor of the female reproductive tract. The aim of this study was to explore the role of lipopolysaccharide (LPS)-induced activation of TLR4/NF-κB signaling pathway on stromal fibroblasts in the pathogenesis of UF. Here, TLR4/NF-κB signaling pathway was more activated in UF, and UF cells (UFC) and UF derived fibroblasts (TAF) than in smooth muscle tissues, smooth muscle cell (SMC) and myometrial fibroblasts (fib) respectively. After lipopolysaccharide (LPS) stimulation, the activity of fib was enhanced, characterized by the increased expression of fibroblast activation protein (FAP), and increased secretion of collagen I and transforming growth factor-β (TGF-β). Moreover, TLR4 inhibitor (VIPER) and siTLR4 can represses LPS-activated fibroblasts and TLR4/NF-κB signaling transduction pathways in fib and UFC cells. Co-cultured with LPS-activated fibroblast enhanced fibroblast activation and TLR4/NF-κB signaling. In conclusion, LPS treatment activated TLR4/NF-κB signaling pathway on fibroblasts, which may involve in the development of UF. Our study indicated reproductive tract infection may be associated with fibroid pathogenesis through TLR4/NF-κB signaling. Targeting NF-κB with inhibitors may hold promises of treating uterine fibroid. PMID:26617709

  14. Lipopolysaccharide activated TLR4/NF-κB signaling pathway of fibroblasts from uterine fibroids

    PubMed Central

    Guo, Jing; Zheng, Lihua; Chen, Li; Luo, Ning; Yang, Weihong; Qu, Xiaoyan; Liu, Mingmin; Cheng, Zhongping

    2015-01-01

    Uterine fibroids (UF) are the most common benign tumor of the female reproductive tract. The aim of this study was to explore the role of lipopolysaccharide (LPS)-induced activation of TLR4/NF-κB signaling pathway on stromal fibroblasts in the pathogenesis of UF. Here, TLR4/NF-κB signaling pathway was more activated in UF, and UF cells (UFC) and UF derived fibroblasts (TAF) than in smooth muscle tissues, smooth muscle cell (SMC) and myometrial fibroblasts (fib) respectively. After lipopolysaccharide (LPS) stimulation, the activity of fib was enhanced, characterized by the increased expression of fibroblast activation protein (FAP), and increased secretion of collagen I and transforming growth factor-β (TGF-β). Moreover, TLR4 inhibitor (VIPER) and siTLR4 can represses LPS-activated fibroblasts and TLR4/NF-κB signaling transduction pathways in fib and UFC cells. Co-cultured with LPS-activated fibroblast enhanced fibroblast activation and TLR4/NF-κB signaling. In conclusion, LPS treatment activated TLR4/NF-κB signaling pathway on fibroblasts, which may involve in the development of UF. Our study indicated reproductive tract infection may be associated with fibroid pathogenesis through TLR4/NF-κB signaling. Targeting NF-κB with inhibitors may hold promises of treating uterine fibroid. PMID:26617709

  15. Extracellular signal-regulated protein kinases 1 and 2 activation by addictive drugs: a signal toward pathological adaptation.

    PubMed

    Pascoli, Vincent; Cahill, Emma; Bellivier, Frank; Caboche, Jocelyne; Vanhoutte, Peter

    2014-12-15

    Addiction is a chronic and relapsing psychiatric disorder that is thought to occur in vulnerable individuals. Synaptic plasticity evoked by drugs of abuse in the so-called neuronal circuits of reward has been proposed to underlie behavioral adaptations that characterize addiction. By increasing dopamine in the striatum, addictive drugs alter the balance of dopamine and glutamate signals converging onto striatal medium-sized spiny neurons (MSNs) and activate intracellular events involved in long-term behavioral alterations. Our laboratory contributed to the identification of salient molecular changes induced by administration of addictive drugs to rodents. We pioneered the observation that a common feature of addictive drugs is to activate, by a double tyrosine/threonine phosphorylation, the extracellular signal-regulated kinases 1 and 2 (ERK1/2) in the striatum, which control a plethora of substrates, some of them being critically involved in cocaine-mediated molecular and behavioral adaptations. Herein, we review how the interplay between dopamine and glutamate signaling controls cocaine-induced ERK1/2 activation in MSNs. We emphasize the key role of N-methyl-D-aspartate receptor potentiation by D1 receptor to trigger ERK1/2 activation and its subsequent nuclear translocation where it modulates both epigenetic and genetic processes engaged by cocaine. We discuss how cocaine-induced long-term synaptic and structural plasticity of MSNs, as well as behavioral adaptations, are influenced by ERK1/2-controlled targets. We conclude that a better knowledge of molecular mechanisms underlying ERK1/2 activation by drugs of abuse and/or its role in long-term neuronal plasticity in the striatum may provide a new route for therapeutic treatment in addiction. PMID:24844603

  16. Allostery through the computational microscope: cAMP activation of a canonical signalling domain

    NASA Astrophysics Data System (ADS)

    Malmstrom, Robert D.; Kornev, Alexandr P.; Taylor, Susan S.; Amaro, Rommie E.

    2015-07-01

    Ligand-induced protein allostery plays a central role in modulating cellular signalling pathways. Here using the conserved cyclic nucleotide-binding domain of protein kinase A's (PKA) regulatory subunit as a prototype signalling unit, we combine long-timescale, all-atom molecular dynamics simulations with Markov state models to elucidate the conformational ensembles of PKA's cyclic nucleotide-binding domain A for the cAMP-free (apo) and cAMP-bound states. We find that both systems exhibit shallow free-energy landscapes that link functional states through multiple transition pathways. This observation suggests conformational selection as the general mechanism of allostery in this canonical signalling domain. Further, we expose the propagation of the allosteric signal through key structural motifs in the cyclic nucleotide-binding domain and explore the role of kinetics in its function. Our approach integrates disparate lines of experimental data into one cohesive framework to understand structure, dynamics and function in complex biological systems.

  17. Neuronal activity regulates remyelination via glutamate signalling to oligodendrocyte progenitors

    PubMed Central

    Gautier, Hélène O. B.; Evans, Kimberley A.; Volbracht, Katrin; James, Rachel; Sitnikov, Sergey; Lundgaard, Iben; James, Fiona; Lao-Peregrin, Cristina; Reynolds, Richard; Franklin, Robin J. M.; Káradóttir, Ragnhildur T

    2015-01-01

    Myelin regeneration can occur spontaneously in demyelinating diseases such as multiple sclerosis (MS). However, the underlying mechanisms and causes of its frequent failure remain incompletely understood. Here we show, using an in-vivo remyelination model, that demyelinated axons are electrically active and generate de novo synapses with recruited oligodendrocyte progenitor cells (OPCs), which, early after lesion induction, sense neuronal activity by expressing AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)/kainate receptors. Blocking neuronal activity, axonal vesicular release or AMPA receptors in demyelinated lesions results in reduced remyelination. In the absence of neuronal activity there is a ∼6-fold increase in OPC number within the lesions and a reduced proportion of differentiated oligodendrocytes. These findings reveal that neuronal activity and release of glutamate instruct OPCs to differentiate into new myelinating oligodendrocytes that recover lost function. Co-localization of OPCs with the presynaptic protein VGluT2 in MS lesions implies that this mechanism may provide novel targets to therapeutically enhance remyelination. PMID:26439639

  18. Neuronal activity regulates remyelination via glutamate signalling to oligodendrocyte progenitors.

    PubMed

    Gautier, Hélène O B; Evans, Kimberley A; Volbracht, Katrin; James, Rachel; Sitnikov, Sergey; Lundgaard, Iben; James, Fiona; Lao-Peregrin, Cristina; Reynolds, Richard; Franklin, Robin J M; Káradóttir, Ragnhildur T

    2015-01-01

    Myelin regeneration can occur spontaneously in demyelinating diseases such as multiple sclerosis (MS). However, the underlying mechanisms and causes of its frequent failure remain incompletely understood. Here we show, using an in-vivo remyelination model, that demyelinated axons are electrically active and generate de novo synapses with recruited oligodendrocyte progenitor cells (OPCs), which, early after lesion induction, sense neuronal activity by expressing AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)/kainate receptors. Blocking neuronal activity, axonal vesicular release or AMPA receptors in demyelinated lesions results in reduced remyelination. In the absence of neuronal activity there is a ∼6-fold increase in OPC number within the lesions and a reduced proportion of differentiated oligodendrocytes. These findings reveal that neuronal activity and release of glutamate instruct OPCs to differentiate into new myelinating oligodendrocytes that recover lost function. Co-localization of OPCs with the presynaptic protein VGluT2 in MS lesions implies that this mechanism may provide novel targets to therapeutically enhance remyelination. PMID:26439639

  19. Mapping Neuronal Activation and the Influence of Adrenergic Signaling during Contextual Memory Retrieval

    ERIC Educational Resources Information Center

    Zhang, Wei-Ping; Guzowski, John F.; Thomas, Steven A.

    2005-01-01

    We recently described a critical role for adrenergic signaling in the hippocampus during contextual and spatial memory retrieval. To determine which neurons are activated by contextual memory retrieval and its sequelae in the presence and absence of adrenergic signaling, transcriptional imaging for the immediate-early gene "Arc" was used in…

  20. Cdc42 Regulation of Kinase Activity and Signaling by the Yeast p21-Activated Kinase Ste20

    PubMed Central

    Lamson, Rachel E.; Winters, Matthew J.; Pryciak, Peter M.

    2002-01-01

    The Saccharomyces cerevisiae kinase Ste20 is a member of the p21-activated kinase (PAK) family with several functions, including pheromone-responsive signal transduction. While PAKs are usually activated by small G proteins and Ste20 binds Cdc42, the role of Cdc42-Ste20 binding has been controversial, largely because Ste20 lacking its entire Cdc42-binding (CRIB) domain retains kinase activity and pheromone response. Here we show that, unlike CRIB deletion, point mutations in the Ste20 CRIB domain that disrupt Cdc42 binding also disrupt pheromone signaling. We also found that Ste20 kinase activity is stimulated by GTP-bound Cdc42 in vivo and this effect is blocked by the CRIB point mutations. Moreover, the Ste20 CRIB and kinase domains bind each other, and mutations that disrupt this interaction cause hyperactive kinase activity and bypass the requirement for Cdc42 binding. These observations demonstrate that the Ste20 CRIB domain is autoinhibitory and that this negative effect is antagonized by Cdc42 to promote Ste20 kinase activity and signaling. Parallel results were observed for filamentation pathway signaling, suggesting that the requirement for Cdc42-Ste20 interaction is not qualitatively different between the mating and filamentation pathways. While necessary for pheromone signaling, the role of the Cdc42-Ste20 interaction does not require regulation by pheromone or the pheromone-activated Gβγ complex, because the CRIB point mutations also disrupt signaling by activated forms of the kinase cascade scaffold protein Ste5. In total, our observations indicate that Cdc42 converts Ste20 to an active form, while pathway stimuli regulate the ability of this active Ste20 to trigger signaling through a particular pathway. PMID:11940652

  1. De novo RRAGC mutation activates mTORC1 signaling in syndromic fetal dilated cardiomyopathy.

    PubMed

    Long, Pamela A; Zimmermann, Michael T; Kim, Maengjo; Evans, Jared M; Xu, Xiaolei; Olson, Timothy M

    2016-08-01

    Idiopathic dilated cardiomyopathy (DCM) is a heritable, genetically heterogeneous disorder with variable age-dependent penetrance. We sought to identify the genetic underpinnings of syndromic, sporadic DCM in a newborn female diagnosed in utero. Postnatal evaluation revealed ventricular dilation and systolic dysfunction, bilateral cataracts, and mild facial dysmorphisms. Comprehensive metabolic and genetic testing, including chromosomal microarray, mitochondrial DNA and targeted RASopathy gene sequencing, and clinical whole exome sequencing for known cardiomyopathy genes was non-diagnostic. Following exclusion of asymptomatic DCM in the parents, trio-based whole exome sequencing was carried out on a research basis, filtering for rare, predicted deleterious de novo and recessive variants. An unreported de novo S75Y mutation was discovered in RRAGC, encoding Ras-related GTP binding C, an essential GTPase in nutrient-activated mechanistic target of rapamycin complex 1 (mTORC1) signaling. In silico protein modeling and molecular dynamics simulation predicted the mutation to disrupt ligand interactions and increase the GDP-bound state. Overexpression of RagC(S75Y) rendered AD293 cells partially insensitive to amino acid deprivation, resulting in increased mTORC1 signaling compared to wild-type RagC. These findings implicate mTORC1 dysregulation through a gain-of-function mutation in RagC as a novel molecular basis for syndromic forms of pediatric heart failure, and expand genotype-phenotype correlation in RASopathy-related syndromes. PMID:27234373

  2. Fumarate hydratase deficiency and cancer: activation of hypoxia signaling?

    PubMed

    Ratcliffe, Peter J

    2007-04-01

    Molecular genetic analysis of hereditary leiomyomatosis and renal cell cancer (HLRCC) unexpectedly revealed germline defects in the gene encoding the Krebs cycle enzyme fumarate hydratase (FH), stimulating great interest in the underlying mechanism of oncogenesis. It has been proposed that the associated accumulation of fumarate competitively inhibits the 2-oxoglutarate-dependent dioxygenases that regulate hypoxia-inducible factor (HIF), thus activating oncogenic hypoxia pathways. In this issue of Cancer Cell, Pollard and colleagues describe a genetic mouse model of FH deficiency that recapitulates aspects of the human disease, including HIF activation and renal cysts, enabling further insights into this unusual cancer syndrome. PMID:17418405

  3. Active output state of the Synechococcus Kai circadian oscillator

    PubMed Central

    Paddock, Mark L.; Boyd, Joseph S.; Adin, Dawn M.; Golden, Susan S.

    2013-01-01

    The mechanisms by which cellular oscillators keep time and transmit temporal information are poorly understood. In cyanobacteria, the timekeeping aspect of the circadian oscillator, composed of the KaiA, KaiB, and KaiC proteins, involves a cyclic progression of phosphorylation states at Ser431 and Thr432 of KaiC. Elucidating the mechanism that uses this temporal information to modulate gene expression is complicated by unknowns regarding the number, structure, and regulatory effects of output components. To identify oscillator signaling states without a complete description of the output machinery, we defined a simple metric, Kai-complex output activity (KOA), that represents the difference in expression of reporter genes between strains that carry specific variants of KaiC and baseline strains that lack KaiC. In the absence of the oscillator, expression of the class 1 paradigm promoter PkaiBC was locked at its usual peak level; conversely, that of the class 2 paradigm promoter PpurF was locked at its trough level. However, for both classes of promoters, peak KOA in wild-type strains coincided late in the circadian cycle near subjective dawn, when KaiC-pST becomes most prevalent (Ser431 is phosphorylated and Thr432 is not). Analogously, peak KOA was detected specifically for the phosphomimetic of KaiC-pST (KaiC-ET). Notably, peak KOA required KaiB, indicating that a KaiBC complex is involved in the output activity. We also found evidence that phosphorylated RpaA (regulator of phycobilisome associated) represses an RpaA-independent output of KOA. A simple mathematical expression successfully simulated two key features of the oscillator—the time of peak KOA and the peak-to-trough amplitude changes. PMID:24043774

  4. Queen signals in a stingless bee: suppression of worker ovary activation and spatial distribution of active compounds

    PubMed Central

    Nunes, Túlio M.; Mateus, Sidnei; Favaris, Arodi P.; Amaral, Mônica F. Z. J.; von Zuben, Lucas G.; Clososki, Giuliano C.; Bento, José M. S.; Oldroyd, Benjamin P.; Silva, Ricardo; Zucchi, Ronaldo; Silva, Denise B.; Lopes, Norberto P.

    2014-01-01

    In most species of social insect the queen signals her presence to her workers via pheromones. Worker responses to queen pheromones include retinue formation around the queen, inhibition of queen cell production and suppression of worker ovary activation. Here we show that the queen signal of the Brazilian stingless bee Friesella schrottkyi is a mixture of cuticular hydrocarbons. Stingless bees are therefore similar to ants, wasps and bumble bees, but differ from honey bees in which the queen's signal mostly comprises volatile compounds originating from the mandibular glands. This shows that cuticular hydrocarbons have independently evolved as the queen's signal across multiple taxa, and that the honey bees are exceptional. We also report the distribution of four active queen-signal compounds by Matrix-assisted laser desorption/ionization (MALDI) imaging. The results indicate a relationship between the behavior of workers towards the queen and the likely site of secretion of the queen's pheromones. PMID:25502598

  5. Ubiquitination in Signaling to and Activation of IKK

    PubMed Central

    Chen, Zhijian J.

    2013-01-01

    A role of polyubiquitination in the activation of IκB kinase (IKK) through a proteasome-independent mechanism was first reported in 1996, but the physiological significance of this finding was not clear until 2000 when TRAF6 was found to be a ubiquitin E3 ligase that catalyzes lysine-63 (K63) polyubiquitination. Since then, several proteins known to regulate IKK have been linked to the ubiquitin pathway. These include the deubiquitination enzymes CYLD and A20 that inhibit IKK, and the ubiquitin binding proteins NEMO and TAB2 which are the regulatory subunits of IKK and TAK1 kinase complexes, respectively. Now accumulating evidence strongly supports a central role of K63 polyubiquitination in IKK activation by multiple immune and inflammatory pathways. Interestingly, recent research suggests that some alternative ubiquitin chains such as linear or K11 ubiquitin chains may also play a role in certain pathways such as the TNF pathway. Here I present a historical narrative of the discovery of the role of ubiquitin in IKK activation, review recent advances in understanding the role and mechanism of ubiquitin-mediated IKK activation, and raise some questions to be resolved in future research. PMID:22435549

  6. Activated AKT/PKB signaling in C. elegans uncouples temporally distinct outputs of DAF-2/insulin-like signaling

    PubMed Central

    Gami, Minaxi S; Iser, Wendy B; Hanselman, Keaton B; Wolkow, Catherine A

    2006-01-01

    Background In the nematode, Caenorhabditis elegans, a conserved insulin-like signaling pathway controls larval development, stress resistance and adult lifespan. AGE-1, a homolog of the p110 catalytic subunit of phosphoinositide 3-kinases (PI3K) comprises the major known effector pathway downstream of the insulin receptor, DAF-2. Phospholipid products of AGE-1/PI3K activate AKT/PKB kinase signaling via PDK-1. AKT/PKB signaling antagonizes nuclear translocation of the DAF-16/FOXO transcription factor. Reduced AGE-1/PI3K signaling permits DAF-16 to direct dauer larval arrest and promote long lifespan in adult animals. In order to study the downstream effectors of AGE-1/PI3K signaling in C. elegans, we conducted a genetic screen for mutations that suppress the constitutive dauer arrest phenotype of age-1(mg109) animals. Results This report describes mutations recovered in a screen for suppressors of the constitutive dauer arrest (daf-C) phenotype of age-1(mg109). Two mutations corresponded to alleles of daf-16. Two mutations were gain-of-function alleles in the genes, akt-1 and pdk-1, encoding phosphoinositide-dependent serine/threonine kinases. A fifth mutation, mg227, located on chromosome X, did not correspond to any known dauer genes, suggesting that mg227 may represent a new component of the insulin pathway. Genetic epistasis analysis by RNAi showed that reproductive development in age-1(mg109);akt-1(mg247) animals was dependent on the presence of pdk-1. Similarly, reproductive development in age-1(mg109);pdk-1(mg261) animals was dependent on akt-1. However, reproductive development in age-1(mg109); mg227 animals required only akt-1, and pdk-1 activity was dispensable in this background. Interestingly, while mg227 suppressed dauer arrest in age-1(mg109) animals, it enhanced the long lifespan phenotype. In contrast, akt-1(mg247) and pdk-1(mg261) did not affect lifespan or stress resistance, while both daf-16 alleles fully suppressed these phenotypes. Conclusion A

  7. Notch2 signaling promotes osteoclast resorption via activation of PYK2.

    PubMed

    Jin, Won Jong; Kim, Bongjun; Kim, Jung-Wook; Kim, Hong-Hee; Ha, Hyunil; Lee, Zang Hee

    2016-05-01

    Notch signaling plays a central role in various cell fate decisions, including skeletal development. Recently, Notch signaling was implicated in osteoclast differentiation and maturation, including the resorption activity of osteoclasts. However, the specific involvement of notch signaling in resorption activity was not fully investigated. Here, we investigated the roles of Notch signaling in the resorption activity of osteoclasts by use of the gamma-secretase inhibitor dibenzazepine (DBZ). Attenuating Notch signaling by DBZ suppressed the expression of NFATc1, a master transcription factor for osteoclast differentiation. However, overexpression of a constitutively active form of NFATc1 did not fully rescue the effects of DBZ. DBZ suppressed the autophosphorylation of PYK2, which is essential for the formation of the podosome belt and sealing zone, with reduced c-Src/PYK2 interaction. We found that RANKL increases PYK2 activation accompanied by increased NICD2 production in osteoclasts. Overexpression of NICD2 in osteoclasts rescued DBZ-mediated suppression of resorption activity with promotion of PYK2 autophosphorylation and microtubule acetylation. Consistent with the in vitro results, DBZ strongly suppressed bone destruction in an interleukin-1-induced bone loss model. Collectively, these results demonstrate that Notch2 in osteoclasts plays a role in the control of resorption activity via the PYK2-c-Src-microtubule signaling pathway. PMID:26829213

  8. Body Morphology, Energy Stores, and Muscle Enzyme Activity Explain Cricket Acoustic Mate Attraction Signaling Variation

    PubMed Central

    Thomson, Ian R.; Darveau, Charles-A.; Bertram, Susan M.

    2014-01-01

    High mating success in animals is often dependent on males signalling attractively with high effort. Since males should be selected to maximize their reproductive success, female preferences for these traits should result in minimal signal variation persisting in the population. However, extensive signal variation persists. The genic capture hypothesis proposes genetic variation persists because fitness-conferring traits depend on an individual's basic processes, including underlying physiological, morphological, and biochemical traits, which are themselves genetically variable. To explore the traits underlying signal variation, we quantified among-male differences in signalling, morphology, energy stores, and the activities of key enzymes associated with signalling muscle metabolism in two species of crickets, Gryllus assimilis (chirper: <20 pulses/chirp) and G. texensis (triller: >20 pulses/chirp). Chirping G. assimilis primarily fuelled signalling with carbohydrate metabolism: smaller individuals and individuals with increased thoracic glycogen stores signalled for mates with greater effort; individuals with greater glycogen phosphorylase activity produced more attractive mating signals. Conversely, the more energetic trilling G. texensis fuelled signalling with both lipid and carbohydrate metabolism: individuals with increased β-hydroxyacyl-CoA dehydrogenase activity and increased thoracic free carbohydrate content signalled for mates with greater effort; individuals with higher thoracic and abdominal carbohydrate content and higher abdominal lipid stores produced more attractive signals. Our findings suggest variation in male reproductive success may be driven by hidden physiological trade-offs that affect the ability to uptake, retain, and use essential nutrients, although the results remain correlational in nature. Our findings indicate that a physiological perspective may help us to understand some of the causes of variation in behaviour. PMID:24608102

  9. Modulation of spontaneous fMRI activity in human visual cortex by behavioral state

    PubMed Central

    Bianciardi, Marta; Fukunaga, Masaki; van Gelderen, Peter; Horovitz, Silvina G.; de Zwart, Jacco A.; Duyn, Jeff H.

    2009-01-01

    The phenomenon of spontaneous fMRI activity is increasingly being exploited to investigate the connectivity of functional networks in human brain with high spatial-resolution. Although mounting evidence points towards a neuronal contribution to this activity, its functional role and dependence on behavioral state remain unclear. In this work, we used BOLD fMRI at 7 T to study the modulation of spontaneous activity in occipital areas by various behavioral conditions, including resting with eyes closed, eyes open with visual fixation, and eyes open with fixation and focal visual stimulation. Spontaneous activity was separated from evoked activity and from signal fluctuations related to cardiac and respiratory cycles. We found that spontaneous activity in visual areas was substantially reduced (amplitude (44%) and coherence (25%)) with the fixation conditions relative to the eyes-closed condition. No significant further modulation was observed when the visual stimulus was added. The observed dependence on behavioral condition suggests that part of spontaneous fMRI signal fluctuations represents neuronal activity. Possible mechanisms for the modulation of spontaneous activity by behavioral state are discussed. The observed linear superposition of spontaneous fMRI activity with focal evoked activity related to visual processing has important implications for fMRI studies, which ideally should take into account the effect of spontaneous activity to properly define brain activations during task conditions. PMID:19028588

  10. Nandrolone reduces activation of Notch signaling in denervated muscle associated with increased Numb expression

    SciTech Connect

    Liu, Xin-Hua; Yao, Shen; Qiao, Rui-Fang; Levine, Alice C.; Kirschenbaum, Alexander; Pan, Jiangping; Wu, Yong; Qin, Weiping; Bauman, William A.; Cardozo, Christopher P.

    2011-10-14

    Highlights: {yields} Nerve transection increased Notch signaling in paralyzed muscle. {yields} Nandrolone prevented denervation-induced Notch signaling. {yields} Nandrolone induced the expression of an inhibitor of the Notch signaling, Numb. {yields} Reduction of denervation-induced Notch signaling by nandrolone is likely through upregulation of Numb. -- Abstract: Nandrolone, an anabolic steroid, slows denervation-atrophy in rat muscle. The molecular mechanisms responsible for this effect are not well understood. Androgens and anabolic steroids activate Notch signaling in animal models of aging and thereby mitigate sarcopenia. To explore the molecular mechanisms by which nandrolone prevents denervation-atrophy, we investigated the effects of nandrolone on Notch signaling in denervated rat gastrocnemius muscle. Denervation significantly increased Notch activity reflected by elevated levels of nuclear Notch intracellular domain (NICD) and expression of Hey1 (a Notch target gene). Activation was greatest at 7 and 35 days after denervation but remained present at 56 days after denervation. Activation of Notch in denervated muscle was prevented by nandrolone associated with upregulated expression of Numb mRNA and protein. These data demonstrate that denervation activates Notch signaling, and that nandrolone abrogates this response associated with increased expression of Numb, suggesting a potential mechanism by which nandrolone reduces denervation-atrophy.

  11. Using neurophysiological signals that reflect cognitive or affective state: six recommendations to avoid common pitfalls

    PubMed Central

    Brouwer, Anne-Marie; Zander, Thorsten O.; van Erp, Jan B. F.; Korteling, Johannes E.; Bronkhorst, Adelbert W.

    2015-01-01

    Estimating cognitive or affective state from neurophysiological signals and designing applications that make use of this information requires expertise in many disciplines such as neurophysiology, machine learning, experimental psychology, and human factors. This makes it difficult to perform research that is strong in all its aspects as well as to judge a study or application on its merits. On the occasion of the special topic “Using neurophysiological signals that reflect cognitive or affective state” we here summarize often occurring pitfalls and recommendations on how to avoid them, both for authors (researchers) and readers. They relate to defining the state of interest, the neurophysiological processes that are expected to be involved in the state of interest, confounding factors, inadvertently “cheating” with classification analyses, insight on what underlies successful state estimation, and finally, the added value of neurophysiological measures in the context of an application. We hope that this paper will support the community in producing high quality studies and well-validated, useful applications. PMID:25983676

  12. ASBESTOS-INDUCED ACTIVATION OF CELL SIGNALING PATHWAYS IN HUMAN BRONCHIAL EPITHELIAL CELLS

    EPA Science Inventory

    Using respiratory epithelial cells transfected with either superoxide dismutase (SOD) or catalase, the authors tested the hypothesis that the activation of the epidermal growth factor (EGF) receptor signal pathway after asbestos exposure involves an oxidative stress. Western blot...

  13. Erythropoietin Synthesis in Renal Myofibroblasts Is Restored by Activation of Hypoxia Signaling.

    PubMed

    Souma, Tomokazu; Nezu, Masahiro; Nakano, Daisuke; Yamazaki, Shun; Hirano, Ikuo; Sekine, Hiroki; Dan, Takashi; Takeda, Kotaro; Fong, Guo-Hua; Nishiyama, Akira; Ito, Sadayoshi; Miyata, Toshio; Yamamoto, Masayuki; Suzuki, Norio

    2016-02-01

    Erythropoietin (Epo) is produced by renal Epo-producing cells (REPs) in a hypoxia-inducible manner. The conversion of REPs into myofibroblasts and coincident loss of Epo-producing ability are the major cause of renal fibrosis and anemia. However, the hypoxic response of these transformed myofibroblasts remains unclear. Here, we used complementary in vivo transgenic and live imaging approaches to better understand the importance of hypoxia signaling in Epo production. Live imaging of REPs in transgenic mice expressing green fluorescent protein from a modified Epo-gene locus revealed that healthy REPs tightly associated with endothelium by wrapping processes around capillaries. However, this association was hampered in states of renal injury-induced inflammation previously shown to correlate with the transition to myofibroblast-transformed renal Epo-producing cells (MF-REPs). Furthermore, activation of hypoxia-inducible factors (HIFs) by genetic inactivation of HIF-prolyl hydroxylases (PHD1, PHD2, and PHD3) selectively in Epo-producing cells reactivated Epo production in MF-REPs. Loss of PHD2 in REPs restored Epo-gene expression in injured kidneys but caused polycythemia. Notably, combined deletions of PHD1 and PHD3 prevented loss of Epo expression without provoking polycythemia. Mice with PHD-deficient REPs also showed resistance to LPS-induced Epo repression in kidneys, suggesting that augmented HIF signaling counterbalances inflammatory stimuli in regulation of Epo production. Thus, augmentation of HIF signaling may be an attractive therapeutic strategy for treating renal anemia by reactivating Epo synthesis in MF-REPs. PMID:26054543

  14. Endothelial juxtaposition of distinct adult stem cells activates angiogenesis signaling molecules in endothelial cells.

    PubMed

    Mohammadi, Elham; Nassiri, Seyed Mahdi; Rahbarghazi, Reza; Siavashi, Vahid; Araghi, Atefeh

    2015-12-01

    Efficacy of therapeutic angiogenesis needs a comprehensive understanding of endothelial cell (EC) function and biological factors and cells that interplay with ECs. Stem cells are considered the key components of pro- and anti-angiogenic milieu in a wide variety of physiopathological states, and interactions of EC-stem cells have been the subject of controversy in recent years. In this study, the potential effects of three tissue-specific adult stem cells, namely rat marrow-derived mesenchymal stem cells (rBMSCs), rat adipose-derived stem cells (rADSCs) and rat muscle-derived satellite cells (rSCs), on the endothelial activation of key angiogenic signaling molecules, including VEGF, Ang-2, VEGFR-2, Tie-2, and Tie2-pho, were investigated. Human umbilical vein endothelial cells (HUVECs) and rat lung microvascular endothelial cells (RLMECs) were cocultured with the stem cells or incubated with the stem cell-derived conditioned media on Matrigel. Following HUVEC-stem cell coculture, CD31-positive ECs were flow sorted and subjected to western blotting to analyze potential changes in the expression of the pro-angiogenic signaling molecules. Elongation and co-alignment of the stem cells were seen along the EC tubes in the EC-stem cell cocultures on Matrigel, with cell-to-cell dye communication in the EC-rBMSC cocultures. Moreover, rBMSCs and rADSCs significantly improved endothelial tubulogenesis in both juxtacrine and paracrine manners. These two latter stem cells dynamically up-regulated VEGF, Ang-2, VREGR-2, and Tie-2 but down-regulated Tie2-pho and the Tie2-pho/Tie-2 ratio in HUVECs. Induction of pro-angiogenic signaling in ECs by marrow- and adipose-derived MSCs further indicates the significance of stem cell milieu in angiogenesis dynamics. PMID:26068799

  15. Renal tubular Notch signaling triggers a prosenescent state after acute kidney injury.

    PubMed

    Sörensen-Zender, Inga; Rong, Song; Susnik, Nathan; Zender, Steffen; Pennekamp, Petra; Melk, Anette; Haller, Hermann; Schmitt, Roland

    2014-04-15

    The aging kidney has a diminished regenerative potential and an increased tendency to develop tubular atrophy and fibrosis after acute injury. In this study, we found that activation of tubular epithelial Notch1 signaling was prolonged in the aging kidney after ischemia/reperfusion (IR) damage. To analyze the consequences of sustained Notch activation, we generated mice with conditional inducible expression of Notch1 intracellular domain (NICD) in proximal tubules. NICD kidneys were analyzed 1 and 4 wk after renal IR. Conditional NICD expression was associated with aggravated tubular damage, a fibrotic phenotype, and the expression of cellular senescence markers p21 and p16(INK4a). In wild-type mice pharmacological inhibition of Notch using the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) improved tubulo-interstitial damage and antagonized the prosenescent pathway activation after IR. In vitro, activation of Notch signaling with delta-like-ligand-4 caused prosenescent changes in tubular cells while inhibition with DAPT attenuated these changes. In conclusion, our data suggest that sustained epithelial Notch activation after IR might contribute to the inferior outcome of old kidneys after injury. Sustained epithelial activation of Notch is associated with a prosenescent phenotype and maladaptive repair. PMID:24573392

  16. Notch signals positively regulate activity of the mTOR pathway in T-cell acute lymphoblastic leukemia

    PubMed Central

    Chan, Steven M.; Weng, Andrew P.; Tibshirani, Robert; Aster, Jon C.

    2007-01-01

    Constitutive Notch activation is required for the proliferation of a subgroup of T-cell acute lymphoblastic leukemia (T-ALL). Downstream pathways that transmit pro-oncogenic signals are not well characterized. To identify these pathways, protein microarrays were used to profile the phosphorylation state of 108 epitopes on 82 distinct signaling proteins in a panel of 13 T-cell leukemia cell lines treated with a gamma-secretase inhibitor (GSI) to inhibit Notch signals. The microarray screen detected GSI-induced hypophosphorylation of multiple signaling proteins in the mTOR pathway. This effect was rescued by expression of the intracellular domain of Notch and mimicked by dominant negative MAML1, confirming Notch specificity. Withdrawal of Notch signals prevented stimulation of the mTOR pathway by mitogenic factors. These findings collectively suggest that the mTOR pathway is positively regulated by Notch in T-ALL cells. The effect of GSI on the mTOR pathway was independent of changes in phosphatidylinositol-3 kinase and Akt activity, but was rescued by expression of c-Myc, a direct transcriptional target of Notch, implicating c-Myc as an intermediary between Notch and mTOR. T-ALL cell growth was suppressed in a highly synergistic manner by simultaneous treatment with the mTOR inhibitor rapamycin and GSI, which represents a rational drug combination for treating this aggressive human malignancy. PMID:17363738

  17. Processing and Analysis of Multichannel Extracellular Neuronal Signals: State-of-the-Art and Challenges

    PubMed Central

    Mahmud, Mufti; Vassanelli, Stefano

    2016-01-01

    In recent years multichannel neuronal signal acquisition systems have allowed scientists to focus on research questions which were otherwise impossible. They act as a powerful means to study brain (dys)functions in in-vivo and in in-vitro animal models. Typically, each session of electrophysiological experiments with multichannel data acquisition systems generate large amount of raw data. For example, a 128 channel signal acquisition system with 16 bits A/D conversion and 20 kHz sampling rate will generate approximately 17 GB data per hour (uncompressed). This poses an important and challenging problem of inferring conclusions from the large amounts of acquired data. Thus, automated signal processing and analysis tools are becoming a key component in neuroscience research, facilitating extraction of relevant information from neuronal recordings in a reasonable time. The purpose of this review is to introduce the reader to the current state-of-the-art of open-source packages for (semi)automated processing and analysis of multichannel extracellular neuronal signals (i.e., neuronal spikes, local field potentials, electroencephalogram, etc.), and the existing Neuroinformatics infrastructure for tool and data sharing. The review is concluded by pinpointing some major challenges that are being faced, which include the development of novel benchmarking techniques, cloud-based distributed processing and analysis tools, as well as defining novel means to share and standardize data. PMID:27313507

  18. Processing and Analysis of Multichannel Extracellular Neuronal Signals: State-of-the-Art and Challenges.

    PubMed

    Mahmud, Mufti; Vassanelli, Stefano

    2016-01-01

    In recent years multichannel neuronal signal acquisition systems have allowed scientists to focus on research questions which were otherwise impossible. They act as a powerful means to study brain (dys)functions in in-vivo and in in-vitro animal models. Typically, each session of electrophysiological experiments with multichannel data acquisition systems generate large amount of raw data. For example, a 128 channel signal acquisition system with 16 bits A/D conversion and 20 kHz sampling rate will generate approximately 17 GB data per hour (uncompressed). This poses an important and challenging problem of inferring conclusions from the large amounts of acquired data. Thus, automated signal processing and analysis tools are becoming a key component in neuroscience research, facilitating extraction of relevant information from neuronal recordings in a reasonable time. The purpose of this review is to introduce the reader to the current state-of-the-art of open-source packages for (semi)automated processing and analysis of multichannel extracellular neuronal signals (i.e., neuronal spikes, local field potentials, electroencephalogram, etc.), and the existing Neuroinformatics infrastructure for tool and data sharing. The review is concluded by pinpointing some major challenges that are being faced, which include the development of novel benchmarking techniques, cloud-based distributed processing and analysis tools, as well as defining novel means to share and standardize data. PMID:27313507

  19. Structure–Activity Relationships for Side Chain Oxysterol Agonists of the Hedgehog Signaling Pathway

    PubMed Central

    2012-01-01

    Oxysterols (OHCs) are byproducts of cholesterol oxidation that are known to activate the Hedeghog (Hh) signaling pathway. While OHCs that incorporate hydroxyl groups throughout the scaffold are known, those that act as agonists of Hh signaling primarily contain a single hydroxyl on the alkyl side chain. We sought to further explore how side chain hydroxylation patterns affect oxysterol-mediated Hh activation, by performing a structure–activity relationship study on a series of synthetic OHCs. The most active analogue, 23(R)-OHC (35), demonstrated potent activation of Hh signaling in two Hh-dependent cell lines (EC50 values 0.54–0.65 μM). In addition, OHC 35 was approximately 3-fold selective for the Hh pathway as compared to the liver X receptor, a nuclear receptor that is also activated by endogenous OHCs. Finally, 35 induced osteogenic differentiation and osteoblast formation in cultured cells, indicating functional agonism of the Hh pathway. PMID:24900386

  20. Stromal TGF-β signaling induces AR activation in prostate cancer

    PubMed Central

    Yang, Feng; Chen, Yizhen; Shen, Tao; Guo, Dan; Dakhova, Olga; Ittmann, Michael M.; Creighton, Chad J.; Zhang, Yiqun; Dang, Truong D.; Rowley, David R.

    2014-01-01

    AR signaling is essential for the growth and survival of prostate cancer (PCa), including most of the lethal castration-resistant PCa (CRPC). We previously reported that TGF-β signaling in prostate stroma promotes prostate tumor angiogenesis and growth. By using a PCa/stroma co-culture model, here we show that stromal TGF-β signaling induces comprehensive morphology changes of PCa LNCaP cells. Furthermore, it induces AR activation in LNCaP cells in the absence of significant levels of androgen, as evidenced by induction of several AR target genes including PSA, TMPRSS2, and KLK4. SD-208, a TGF-β receptor 1 specific inhibitor, blocks this TGF-β induced biology. Importantly, stromal TGF-β signaling together with DHT induce robust activation of AR. MDV3100 effectively blocks DHT-induced, but not stromal TGF-β signaling induced AR activation in LNCaP cells, indicating that stromal TGF-β signaling induces both ligand-dependent and ligand-independent AR activation in PCa. TGF-β induces the expression of several growth factors and cytokines in prostate stromal cells, including IL-6, and BMP-6. Interestingly, BMP-6 and IL-6 together induces robust AR activation in these co-cultures, and neutralizing antibodies against BMP-6 and IL-6 attenuate this action. Altogether, our study strongly suggests tumor stromal microenvironment induced AR activation as a direct mechanism of CRPC. PMID:25333263

  1. Active transport improves the precision of linear long distance molecular signalling

    NASA Astrophysics Data System (ADS)

    Godec, Aljaž; Metzler, Ralf

    2016-09-01

    Molecular signalling in living cells occurs at low copy numbers and is thereby inherently limited by the noise imposed by thermal diffusion. The precision at which biochemical receptors can count signalling molecules is intimately related to the noise correlation time. In addition to passive thermal diffusion, messenger RNA and vesicle-engulfed signalling molecules can transiently bind to molecular motors and are actively transported across biological cells. Active transport is most beneficial when trafficking occurs over large distances, for instance up to the order of 1 metre in neurons. Here we explain how intermittent active transport allows for faster equilibration upon a change in concentration triggered by biochemical stimuli. Moreover, we show how intermittent active excursions induce qualitative changes in the noise in effectively one-dimensional systems such as dendrites. Thereby they allow for significantly improved signalling precision in the sense of a smaller relative deviation in the concentration read-out by the receptor. On the basis of linear response theory we derive the exact mean field precision limit for counting actively transported molecules. We explain how intermittent active excursions disrupt the recurrence in the molecular motion, thereby facilitating improved signalling accuracy. Our results provide a deeper understanding of how recurrence affects molecular signalling precision in biological cells and novel medical-diagnostic devices.

  2. Active regulation of receptor ratios controls integration of quorum-sensing signals in Vibrio harveyi

    PubMed Central

    Teng, Shu-Wen; Schaffer, Jessica N; Tu, Kimberly C; Mehta, Pankaj; Lu, Wenyun; Ong, N P; Bassler, Bonnie L; Wingreen, Ned S

    2011-01-01

    Quorum sensing is a chemical signaling mechanism used by bacteria to communicate and orchestrate group behaviors. Multiple feedback loops exist in the quorum-sensing circuit of the model bacterium Vibrio harveyi. Using fluorescence microscopy of individual cells, we assayed the activity of the quorum-sensing circuit, with a focus on defining the functions of the feedback loops. We quantitatively investigated the signaling input–output relation both in cells with all feedback loops present as well as in mutants with specific feedback loops disrupted. We found that one of the feedback loops regulates receptor ratios to control the integration of multiple signals. Together, the feedback loops affect the input–output dynamic range of signal transmission and the noise in the output. We conclude that V. harveyi employs multiple feedback loops to simultaneously control quorum-sensing signal integration and to ensure signal transmission fidelity. PMID:21613980

  3. Detection of Bidirectional Signaling During Integrin Activation and Neutrophil Adhesion

    PubMed Central

    Altman, Stuart M.; Dixit, Neha; Simon, Scott I.

    2014-01-01

    Neutrophil arrest and migration on inflamed endothelium is dependent upon a conformational shift in CD11a/CD18 (LFA-1) from a low to high affinity and clustered state which determines the strength and lifetime of bond formation with intracellular adhesion molecule 1 (ICAM-1). Cytoskeletal adaptor proteins kindlin-3 and talin-1 anchor clustered LFA-1 to the cytoskeleton and support the transition from neutrophil rolling to arrest. We employ microfluidic flow channels and total internal reflection fluorescence microscopy to evaluate the spatiotemporal regulation of LFA-1 affinity and bond formation that facilitate the transition from neutrophil rolling to arrest. Methodology is presented to correlate the relationship between integrin conformation, bond formation with ICAM-1, and cytoskeletal engagement and adhesion strengthening necessary to achieve a migratory phenotype. PMID:24504956

  4. Global and structured waves of rs-fMRI signal identified as putative propagation of spontaneous neural activity.

    PubMed

    Amemiya, Shiori; Takao, Hidemasa; Hanaoka, Shohei; Ohtomo, Kuni

    2016-06-01

    Conventional resting-state fMRI (rs-fMRI) studies have focused on investigating the synchronous neural activity in functionally relevant distant regions that are termed as resting-state networks. On the other hand, less is known about the spatiotemporal dynamics of the spontaneous activity of the brain. By examining the characteristics of both rs-fMRI and vascular time lag that was measured using dynamic susceptibility contrast-enhanced perfusion weighted imaging, the present study identifies several structured propagation of the rs-fMRI signal as putative neural streams. Temporal shift of both rs-fMRI and perfusion imaging data in each voxel compared with the averaged whole-brain signal was computed using cross-correlation analysis. In contrast to the uniformity of the vascular time lag across subjects, whole-brain rs-fMRI time lag was estimated to be composed of three independent components. After regression of vascular time lag, independent component analysis was applied to rs-fMRI data. The putative neural streams showed slow propagation of the signal from task-positive regions to main nodes of the default mode network, which may represent a mode of transmission underlying the interactions among the resting-state networks. PMID:27012499

  5. Detection of dark states in two-dimensional electronic photon-echo signals via ground-state coherence

    SciTech Connect

    Egorova, Dassia

    2015-06-07

    Several recent experiments report on possibility of dark-state detection by means of so called beating maps of two-dimensional photon-echo spectroscopy [Ostroumov et al., Science 340, 52 (2013); Bakulin et al., Ultrafast Phenomena XIX (Springer International Publishing, 2015)]. The main idea of this detection scheme is to use coherence induced upon the laser excitation as a very sensitive probe. In this study, we investigate the performance of ground-state coherence in the detection of dark electronic states. For this purpose, we simulate beating maps of several models where the excited-state coherence can be hardly detected and is assumed not to contribute to the beating maps. The models represent strongly coupled electron-nuclear dynamics involving avoided crossings and conical intersections. In all the models, the initially populated optically accessible excited state decays to a lower-lying dark state within few hundreds femtoseconds. We address the role of Raman modes and of interstate-coupling nature. Our findings suggest that the presence of low-frequency Raman active modes significantly increases the chances for detection of dark states populated via avoided crossings, whereas conical intersections represent a more challenging task.

  6. Amplification and attenuation of a probe signal by doubly dressed states

    NASA Astrophysics Data System (ADS)

    Shevchenko, S. N.; Oelsner, G.; Greenberg, Ya. S.; Macha, P.; Karpov, D. S.; Grajcar, M.; Hübner, U.; Omelyanchouk, A. N.; Il'ichev, E.

    2014-05-01

    We analyze a system composed of a qubit coupled to the electromagnetic fields in two high quality quantum oscillators. A particular realization of such a system is the superconducting qubit coupled to a transmission-line resonator driven by two signals with frequencies close to the resonator's harmonics. This doubly driven system can be described in terms of the doubly dressed qubit states. Our calculations demonstrate the possibility to change the number of photons in the resonator and the transmission of the fundamental-mode signal over a wide parameter range exploiting resonances with the dressed qubit. Experiments show that in the case of high quality resonators the dressed energy levels and corresponding resonance conditions can be probed, even for high driving amplitudes. The interaction of the qubit with photons of two harmonics can be used for the creation of quantum amplifiers or attenuators.

  7. New Insights into Glomerular Parietal Epithelial Cell Activation and Its Signaling Pathways in Glomerular Diseases

    PubMed Central

    Su, Hua; Chen, Shan; He, Fang-Fang; Wang, Yu-Mei; Bondzie, Philip; Zhang, Chun

    2015-01-01

    The glomerular parietal epithelial cells (PECs) have aroused an increasing attention recently. The proliferation of PECs is the main feature of crescentic glomerulonephritis; besides that, in the past decade, PEC activation has been identified in several types of noninflammatory glomerulonephropathies, such as focal segmental glomerulosclerosis, diabetic glomerulopathy, and membranous nephropathy. The pathogenesis of PEC activation is poorly understood; however, a few studies delicately elucidate the potential mechanisms and signaling pathways implicated in these processes. In this review we will focus on the latest observations and concepts about PEC activation in glomerular diseases and the newest identified signaling pathways in PEC activation. PMID:25866774

  8. Active control of shocks and sonic boom ground signal

    NASA Astrophysics Data System (ADS)

    Yagiz, Bedri

    The manipulation of a flow field to obtain a desired change is a much heightened subject. Active flow control has been the subject of the major research areas in fluid mechanics for the past two decades. It offers new solutions for mitigation of shock strength, sonic boom alleviation, drag minimization, reducing blade-vortex interaction noise in helicopters, stall control and the performance maximization of existing designs to meet the increasing requirements of the aircraft industries. Despite the wide variety of the potential applications of active flow control, the majority of studies have been performed at subsonic speeds. The active flow control cases were investigated in transonic speed in this study. Although the active flow control provides significant improvements, the sensibility of aerodynamic performance to design parameters makes it a nontrivial and expensive problem, so the designer has to optimize a number of different parameters. For the purpose of gaining understanding of the active flow control concepts, an automated optimization cycle process was generated. Also, the optimization cycle reduces cost and turnaround time. The mass flow coefficient, location, width and angle were chosen as design parameters to maximize the aerodynamic performance of an aircraft. As the main contribution of this study, a detailed parametric study and optimization process were presented. The second step is to appraise the practicability of weakening the shock wave and thereby reducing the wave drag in transonic flight regime using flow control devices such as two dimensional contour bump, individual jet actuator, and also the hybrid control which includes both control devices together, thereby gaining the desired improvements in aerodynamic performance of the air-vehicle. After this study, to improve the aerodynamic performance, the flow control and shape parameters are optimized separately, combined, and in a serial combination. The remarkable part of all these

  9. K+ efflux agonists induce NLRP3 inflammasome activation independently of Ca2+ signaling1

    PubMed Central

    Katsnelson, Michael A.; Rucker, L. Graham; Russo, Hana M.; Dubyak, George R.

    2015-01-01

    Perturbation of intracellular ion homeostasis is a major cellular stress signal for activation of NLRP3 inflammasome signaling that results in caspase-1 mediated production of IL-1β and pyroptosis. However, the relative contributions of decreased cytosolic [K+] versus increased cytosolic [Ca2+] remain disputed and incompletely defined. We investigated roles for elevated cytosolic [Ca2+] in NLRP3 activation and downstream inflammasome signaling responses in primary murine dendritic cells and macrophages in response to two canonical NLRP3 agonists (ATP and nigericin) that facilitate primary K+ efflux by mechanistically distinct pathways or the lysosome-destabilizing agonist Leu-Leu-O-methyl ester (LLME). The study provides three major findings relevant to this unresolved area of NLRP3 regulation. First, increased cytosolic [Ca2+] was neither a necessary nor sufficient signal for the NLRP3 inflammasome cascade during activation by endogenous ATP-gated P2X7 receptor channels, the exogenous bacterial ionophore nigericin, or the lysosomotropic agent LLME. Second, agonists for three Ca2+-mobilizing G protein-coupled receptors (formyl peptide receptor/FPR; P2Y2 purinergic receptor/P2Y2R; calcium-sensing receptor/CaSR) expressed in murine dendritic cells were ineffective as activators of rapidly induced NLRP3 signaling when directly compared to the K+ efflux agonists. Third, the intracellular Ca2+ buffer, BAPTA, and the channel blocker, 2-aminoethoxydiphenyl borate (2-APB), widely used reagents for disruption of Ca2+-dependent signaling pathways, strongly suppressed nigericin-induced NLRP3 inflammasome signaling via mechanisms dissociated from their canonical or expected effects on Ca2+ homeostasis. The results indicate that the ability of K+ efflux agonists to activate NLRP3 inflammasome signaling can be dissociated from changes in cytosolic [Ca2+] as a necessary or sufficient signal. PMID:25762778

  10. Insulin Signaling in Insulin Resistance States and Cancer: A Modeling Analysis

    PubMed Central

    Bertuzzi, Alessandro; Conte, Federica; Mingrone, Geltrude; Papa, Federico; Salinari, Serenella

    2016-01-01

    Insulin resistance is the common denominator of several diseases including type 2 diabetes and cancer, and investigating the mechanisms responsible for insulin signaling impairment is of primary importance. A mathematical model of the insulin signaling network (ISN) is proposed and used to investigate the dose-response curves of components of this network. Experimental data of C2C12 myoblasts with phosphatase and tensin homologue (PTEN) suppressed and data of L6 myotubes with induced insulin resistance have been analyzed by the model. We focused particularly on single and double Akt phosphorylation and pointed out insulin signaling changes related to insulin resistance. Moreover, a new characterization of the upstream signaling of the mammalian target of rapamycin complex 2 (mTORC2) is presented. As it is widely recognized that ISN proteins have a crucial role also in cell proliferation and death, the ISN model was linked to a cell population model and applied to data of a cell line of acute myeloid leukemia treated with a mammalian target of rapamycin inhibitor with antitumor activity. The analysis revealed simple relationships among the concentrations of ISN proteins and the parameters of the cell population model that characterize cell cycle progression and cell death. PMID:27149630

  11. Deoxycholic acid mediates non-canonical EGFR-MAPK activation through the induction of calcium signaling in colon cancer cells.

    PubMed

    Centuori, Sara M; Gomes, Cecil J; Trujillo, Jesse; Borg, Jamie; Brownlee, Joshua; Putnam, Charles W; Martinez, Jesse D

    2016-07-01

    Obesity and a western diet have been linked to high levels of bile acids and the development of colon cancer. Specifically, increased levels of the bile acid deoxycholic acid (DCA), an established tumor promoter, has been shown to correlate with increased development of colorectal adenomas and progression to carcinoma. Herein we investigate the mechanism by which DCA leads to EGFR-MAPK activation, a candidate mechanism by which DCA may promote colorectal tumorigenesis. DCA treated colon cancer cells exhibited strong and prolonged activation of ERK1/2 when compared to EGF treatment alone. We also showed that DCA treatment prevents EGFR degradation as opposed to the canonical EGFR recycling observed with EGF treatment. Moreover, the combination of DCA and EGF treatment displayed synergistic activity, suggesting DCA activates MAPK signaling in a non-canonical manner. Further evaluation showed that DCA treatment increased intracellular calcium levels and CAMKII phosphorylation, and that blocking calcium with BAPTA-AM abrogated MAPK activation induced by DCA, but not by EGF. Finally we showed that DCA-induced CAMKII leads to MAPK activation through the recruitment of c-Src. Taken together, we demonstrated that DCA regulates MAPK activation through calcium signaling, an alternative mechanism not previously recognized in human colon cancer cells. Importantly, this mechanism allows for EGFR to escape degradation and thus achieve a constitutively active state, which may explain its tumor promoting effects. PMID:27086143

  12. Signal processing techniques for damage detection with piezoelectric wafer active sensors and embedded ultrasonic structural radar

    NASA Astrophysics Data System (ADS)

    Yu, Lingyu; Bao, Jingjing; Giurgiutiu, Victor

    2004-07-01

    Embedded ultrasonic structural radar (EUSR) algorithm is developed for using piezoelectric wafer active sensor (PWAS) array to detect defects within a large area of a thin-plate specimen. Signal processing techniques are used to extract the time of flight of the wave packages, and thereby to determine the location of the defects with the EUSR algorithm. In our research, the transient tone-burst wave propagation signals are generated and collected by the embedded PWAS. Then, with signal processing, the frequency contents of the signals and the time of flight of individual frequencies are determined. This paper starts with an introduction of embedded ultrasonic structural radar algorithm. Then we will describe the signal processing methods used to extract the time of flight of the wave packages. The signal processing methods being used include the wavelet denoising, the cross correlation, and Hilbert transform. Though hardware device can provide averaging function to eliminate the noise coming from the signal collection process, wavelet denoising is included to ensure better signal quality for the application in real severe environment. For better recognition of time of flight, cross correlation method is used. Hilbert transform is applied to the signals after cross correlation in order to extract the envelope of the signals. Signal processing and EUSR are both implemented by developing a graphical user-friendly interface program in LabView. We conclude with a description of our vision for applying EUSR signal analysis to structural health monitoring and embedded nondestructive evaluation. To this end, we envisage an automatic damage detection application utilizing embedded PWAS, EUSR, and advanced signal processing.

  13. Nandrolone reduces activation of Notch signaling in denervated muscle associated with increased Numb expression.

    PubMed

    Liu, Xin-Hua; Yao, Shen; Qiao, Rui-Fang; Levine, Alice C; Kirschenbaum, Alexander; Pan, Jiangping; Wu, Yong; Qin, Weiping; Bauman, William A; Cardozo, Christopher P

    2011-10-14

    Nandrolone, an anabolic steroid, slows denervation-atrophy in rat muscle. The molecular mechanisms responsible for this effect are not well understood. Androgens and anabolic steroids activate Notch signaling in animal models of aging and thereby mitigate sarcopenia. To explore the molecular mechanisms by which nandrolone prevents denervation-atrophy, we investigated the effects of nandrolone on Notch signaling in denervated rat gastrocnemius muscle. Denervation significantly increased Notch activity reflected by elevated levels of nuclear Notch intracellular domain (NICD) and expression of Hey1 (a Notch target gene). Activation was greatest at 7 and 35 days after denervation but remained present at 56 days after denervation. Activation of Notch in denervated muscle was prevented by nandrolone associated with upregulated expression of Numb mRNA and protein. These data demonstrate that denervation activates Notch signaling, and that nandrolone abrogates this response associated with increased expression of Numb, suggesting a potential mechanism by which nandrolone reduces denervation-atrophy. PMID:21945932

  14. Activation of Symbiosis Signaling by Arbuscular Mycorrhizal Fungi in Legumes and Rice[OPEN

    PubMed Central

    Sun, Jongho; Miller, J. Benjamin; Granqvist, Emma; Wiley-Kalil, Audrey; Gobbato, Enrico; Maillet, Fabienne; Cottaz, Sylvain; Samain, Eric; Venkateshwaran, Muthusubramanian; Fort, Sébastien; Morris, Richard J.; Ané, Jean-Michel; Dénarié, Jean; Oldroyd, Giles E.D.

    2015-01-01

    Establishment of arbuscular mycorrhizal interactions involves plant recognition of diffusible signals from the fungus, including lipochitooligosaccharides (LCOs) and chitooligosaccharides (COs). Nitrogen-fixing rhizobial bacteria that associate with leguminous plants also signal to their hosts via LCOs, the so-called Nod factors. Here, we have assessed the induction of symbiotic signaling by the arbuscular mycorrhizal (Myc) fungal-produced LCOs and COs in legumes and rice (Oryza sativa). We show that Myc-LCOs and tetra-acetyl chitotetraose (CO4) activate the common symbiosis signaling pathway, with resultant calcium oscillations in root epidermal cells of Medicago truncatula and Lotus japonicus. The nature of the calcium oscillations is similar for LCOs produced by rhizobial bacteria and by mycorrhizal fungi; however, Myc-LCOs activate distinct gene expression. Calcium oscillations were activated in rice atrichoblasts by CO4, but not the Myc-LCOs, whereas a mix of CO4 and Myc-LCOs activated calcium oscillations in rice trichoblasts. In contrast, stimulation of lateral root emergence occurred following treatment with Myc-LCOs, but not CO4, in M. truncatula, whereas both Myc-LCOs and CO4 were active in rice. Our work indicates that legumes and non-legumes differ in their perception of Myc-LCO and CO signals, suggesting that different plant species respond to different components in the mix of signals produced by arbuscular mycorrhizal fungi. PMID:25724637

  15. Constraining the neutron star equation of state with gravitational wave signals from coalescing binary neutron stars

    NASA Astrophysics Data System (ADS)

    Agathos, M.; Meidam, J.; Del Pozzo, W.; Li, T. G. F.; Tompitak, M.; Veitch, J.; Vitale, S.; Van Den Broeck, C.

    2015-07-01

    Recently exploratory studies were performed on the possibility of constraining the neutron star equation of state (EOS) using signals from coalescing binary neutron stars, or neutron star-black hole systems, as they will be seen in upcoming advanced gravitational wave detectors such as Advanced LIGO and Advanced Virgo. In particular, it was estimated to what extent the combined information from multiple detections would enable one to distinguish between different equations of state through hypothesis ranking or parameter estimation. Under the assumption of zero neutron star spins both in signals and in template waveforms and considering tidal effects to 1 post-Newtonian (1PN) order, it was found that O (20 ) sources would suffice to distinguish between a stiff, moderate, and soft equation of state. Here we revisit these results, this time including neutron star tidal effects to the highest order currently known, termination of gravitational waveforms at the contact frequency, neutron star spins, and the resulting quadrupole-monopole interaction. We also take the masses of neutron stars in simulated sources to be distributed according to a relatively strongly peaked Gaussian, as hinted at by observations, but without assuming that the data analyst will necessarily have accurate knowledge of this distribution for use as a mass prior. We find that especially the effect of the latter is dramatic, necessitating many more detections to distinguish between different EOSs and causing systematic biases in parameter estimation, on top of biases due to imperfect understanding of the signal model pointed out in earlier work. This would get mitigated if reliable prior information about the mass distribution could be folded into the analyses.

  16. A proteomic approach reveals integrin activation state-dependent control of microtubule cortical targeting.

    PubMed

    Byron, Adam; Askari, Janet A; Humphries, Jonathan D; Jacquemet, Guillaume; Koper, Ewa J; Warwood, Stacey; Choi, Colin K; Stroud, Matthew J; Chen, Christopher S; Knight, David; Humphries, Martin J

    2015-01-01

    Integrin activation, which is regulated by allosteric changes in receptor conformation, enables cellular responses to the chemical, mechanical and topological features of the extracellular microenvironment. A global view of how activation state converts the molecular composition of the region proximal to integrins into functional readouts is, however, lacking. Here, using conformation-specific monoclonal antibodies, we report the isolation of integrin activation state-dependent complexes and their characterization by mass spectrometry. Quantitative comparisons, integrating network, clustering, pathway and image analyses, define multiple functional protein modules enriched in a conformation-specific manner. Notably, active integrin complexes are specifically enriched for proteins associated with microtubule-based functions. Visualization of microtubules on micropatterned surfaces and live cell imaging demonstrate that active integrins establish an environment that stabilizes microtubules at the cell periphery. These data provide a resource for the interrogation of the global molecular connections that link integrin activation to adhesion signalling. PMID:25609142

  17. A proteomic approach reveals integrin activation state-dependent control of microtubule cortical targeting

    PubMed Central

    Byron, Adam; Askari, Janet A.; Humphries, Jonathan D.; Jacquemet, Guillaume; Koper, Ewa J.; Warwood, Stacey; Choi, Colin K.; Stroud, Matthew J.; Chen, Christopher S.; Knight, David; Humphries, Martin J.

    2015-01-01

    Integrin activation, which is regulated by allosteric changes in receptor conformation, enables cellular responses to the chemical, mechanical and topological features of the extracellular microenvironment. A global view of how activation state converts the molecular composition of the region proximal to integrins into functional readouts is, however, lacking. Here, using conformation-specific monoclonal antibodies, we report the isolation of integrin activation state-dependent complexes and their characterization by mass spectrometry. Quantitative comparisons, integrating network, clustering, pathway and image analyses, define multiple functional protein modules enriched in a conformation-specific manner. Notably, active integrin complexes are specifically enriched for proteins associated with microtubule-based functions. Visualization of microtubules on micropatterned surfaces and live cell imaging demonstrate that active integrins establish an environment that stabilizes microtubules at the cell periphery. These data provide a resource for the interrogation of the global molecular connections that link integrin activation to adhesion signalling. PMID:25609142

  18. Hedgehog signal activation coordinates proliferation and differentiation of fetal liver progenitor cells

    SciTech Connect

    Hirose, Yoshikazu; Itoh, Tohru; Miyajima, Atsushi

    2009-09-10

    Hedgehog (Hh) signaling plays crucial roles in development and homeostasis of various organs. In the adult liver, it regulates proliferation and/or viability of several types of cells, particularly under injured conditions, and is also implicated in stem/progenitor cell maintenance. However, the role of this signaling pathway during the normal developmental process of the liver remains elusive. Although Sonic hedgehog (Shh) is expressed in the ventral foregut endoderm from which the liver derives, the expression disappears at the onset of the liver bud formation, and its possible recurrence at the later stages has not been investigated. Here we analyzed the activation and functional relevance of Hh signaling during the mouse fetal liver development. At E11.5, Shh and an activation marker gene for Hh signaling, Gli1, were expressed in Dlk{sup +} hepatoblasts, the fetal liver progenitor cells, and the expression was rapidly decreased thereafter as the development proceeded. In the culture of Dlk{sup +} hepatoblasts isolated from the E11.5 liver, activation of Hh signaling stimulated their proliferation and this effect was cancelled by a chemical Hh signaling inhibitor, cyclopamine. In contrast, hepatocyte differentiation of Dlk{sup +} hepatoblasts in vitro as manifested by the marker gene expression and acquisition of ammonia clearance activity was significantly inhibited by forced activation of Hh signaling. Taken together, these results demonstrate the temporally restricted manner of Hh signal activation and its role in promoting the hepatoblast proliferation, and further suggest that the pathway needs to be shut off for the subsequent hepatic differentiation of hepatoblasts to proceed normally.

  19. Pterygium epithelium abnormal differentiation related to activation of extracellular signal-regulated kinase signaling pathway in vitro

    PubMed Central

    Peng, Juan; Sha, Xiang-Yin; Liu, Yi; Yang, Rui-Ming; Wen, Ye

    2015-01-01

    AIM To investigate whether the abnormal differentiation of the pterygium epithelium is related to the extracellular signal-regulated kinase (ERK) signaling pathway in vitro. METHODS The expression levels of phosphorylated ERK (P-ERK), keratin family members including K19 and K10 and the ocular master control gene Pax-6 were measured in 16 surgically excised pterygium tissues and 12 eye bank conjunctiva. In colony-forming cell assays, the differences in clone morphology and in K10, K19, P-ERK and Pax-6 expression between the head and body were investigated. When cocultured with the ERK signaling pathway inhibitor PD98059, the changes in clone morphology, colony-forming efficiency, differentiated marker K10, K19 and Pax-6 expression and P-ERK protein expression level were examined by immunoreactivity and Western blot analysis. RESULTS The expression of K19 and Pax-6 decreased in the pterygium, especially in the head. No staining of K10 was found in the normal conjunctiva epithelium, but it was found to be expressed in the superficial cells in the head of the pterygium. Characteristic upregulation of P-ERK was observed by immunohistochemistry. The clone from the head with more differentiated cells in the center expressed more K10, and the clone from the body expressed more K19. The P-ERK protein level increased in the pterygium epithelium compared with conjunctiva and decreased when cocultured with PD98059. The same medium with the ERK inhibitor PD98059 was more effective in promoting clonal growth than conventional medium with 3T3 murine feeder layers. It was observed that the epithelium clone co-cultured with the inhibitor had decreased K10 expression and increased K19 and Pax-6 expression. CONCLUSION We suggest ERK signaling pathway activation might play a role in the pterygium epithelium abnormal differentiation. PMID:26682158

  20. Hepatic Glycogen Supercompensation Activates AMP-Activated Protein Kinase, Impairs Insulin Signaling, and Reduces Glycogen Deposition in the Liver

    PubMed Central

    Winnick, Jason J.; An, Zhibo; Ramnanan, Christopher J.; Smith, Marta; Irimia, Jose M.; Neal, Doss W.; Moore, Mary Courtney; Roach, Peter J.; Cherrington, Alan D.

    2011-01-01

    OBJECTIVE The objective of this study was to determine how increasing the hepatic glycogen content would affect the liver’s ability to take up and metabolize glucose. RESEARCH DESIGN AND METHODS During the first 4 h of the study, liver glycogen deposition was stimulated by intraportal fructose infusion in the presence of hyperglycemic-normoinsulinemia. This was followed by a 2-h hyperglycemic-normoinsulinemic control period, during which the fructose infusion was stopped, and a 2-h experimental period in which net hepatic glucose uptake (NHGU) and disposition (glycogen, lactate, and CO2) were measured in the absence of fructose but in the presence of a hyperglycemic-hyperinsulinemic challenge including portal vein glucose infusion. RESULTS Fructose infusion increased net hepatic glycogen synthesis (0.7 ± 0.5 vs. 6.4 ± 0.4 mg/kg/min; P < 0.001), causing a large difference in hepatic glycogen content (62 ± 9 vs. 100 ± 3 mg/g; P < 0.001). Hepatic glycogen supercompensation (fructose infusion group) did not alter NHGU, but it reduced the percent of NHGU directed to glycogen (79 ± 4 vs. 55 ± 6; P < 0.01) and increased the percent directed to lactate (12 ± 3 vs. 29 ± 5; P = 0.01) and oxidation (9 ± 3 vs. 16 ± 3; P = NS). This change was associated with increased AMP-activated protein kinase phosphorylation, diminished insulin signaling, and a shift in glycogenic enzyme activity toward a state discouraging glycogen accumulation. CONCLUSIONS These data indicate that increases in hepatic glycogen can generate a state of hepatic insulin resistance, which is characterized by impaired glycogen synthesis despite preserved NHGU. PMID:21270252

  1. State-dependent changes in astrocyte regulation of extrasynaptic NMDA receptor signalling in neurosecretory neurons.

    PubMed

    Fleming, Tiffany M; Scott, Victoria; Naskar, Krishna; Joe, Natalie; Brown, Colin H; Stern, Javier E

    2011-08-15

    Despite the long-established presence of glutamate NMDA receptors at extrasynaptic sites (eNMDARs), their functional roles remain poorly understood. Factors influencing the concentration and time course of glutamate in the extrasynaptic space, such as the topography of the neuronal–glial microenvironment, as well as glial glutamate transporters, are expected to affect eNMDAR-mediated signalling strength. In this study, we used in vitro and in vivo electrophysiological recordings to assess the properties, functional relevance and modulation of a persistent excitatory current mediated by activation of eNMDARs in hypothalamic supraoptic nucleus (SON) neurons. We found that ambient glutamate of a non-synaptic origin activates eNMDARs to mediate a persistent excitatory current (termed tonic I(NMDA)), which tonically stimulates neuronal activity. Pharmacological blockade of GLT1 astrocyte glutamate transporters, as well as the gliotoxin α-aminodadipic acid, enhanced tonic I(NMDA) and neuronal activity, supporting an astrocyte regulation of tonic I(NMDA) strength. Dehydration, a physiological challenge known to increase SON firing activity and to induce neuroglial remodelling, including reduced neuronal ensheathment by astrocyte processes, resulted in blunted GLT1 efficacy, enhanced tonic I(NMDA) strength, and increased neuronal activity. Taken together, our studies support the view that glial modulation of tonic I(NMDA) activation contributes to regulation of SON neuronal activity, contributing in turn to neuronal homeostatic responses during a physiological challenge. PMID:21690192

  2. [Music-Acoustic Signals Controlled by Subject's Brain Potentials in the Correction of Unfavorable Functional States].

    PubMed

    Fedotchev, A I; Bondar, A T; Bakhchina, A V; Parin, S B; Polevaya, S A; Radchenko, G S

    2016-01-01

    Literature review and the results of own studies on the development and experimental testing of musical EEG neurofeedback technology are presented. The technology is based on exposure of subjects to music or music-like signals that are organized in strict accordance with the current values of brain potentials of the patient. The main attention is paid to the analysis of the effectiveness of several versions of the technology, using specific and meaningful for the individual narrow-frequency EEG oscillators during the correction of unfavorable changes of the functional state. PMID:27149824

  3. Tritium activities in the United States

    SciTech Connect

    Anderson, J.L.; LaMarche, P.

    1995-07-01

    There have been many significant changes in the status of tritium activities in the US since the 4th Tritium Conference in October, 1991. The replacement Tritium Facility (RTF) at Savannah River Site and the Weapons Engineering Tritium Facility (WETF) at the Los Alamos National Laboratory are now operational with tritium. The Tokamak Fusion Test Reactor (TFTR) has initiated a highly successful experimental campaign studying DT plasmas, and has produced more than 10 Megawatts (MW) of fusion power in a D-T plasma. Sandia National Laboratory has ceased tritium operations at the Tritium Research Laboratory (TRL) and many of the activities previously performed there have been transferred to Los Alamos and Savannah River. The tritium laboratory at Lawrence Livermore National Laboratory has reduced the tritium inventory to <5 grams. The Tritium Systems Test Assembly (TSTA) at Los Alamos continues to be at the forefront of tritium technology and safety development for the fusion energy program.

  4. Calcium signaling in mammalian egg activation and embryo development: Influence of subcellular localization

    PubMed Central

    Miao, Yi-Liang; Williams, Carmen J.

    2012-01-01

    Calcium (Ca2+) signals drive the fundamental events surrounding fertilization and the activation of development in all species examined to date. Initial studies of Ca2+ signaling at fertilization in marine animals were tightly linked to new discoveries of bioluminescent proteins and their use as fluorescent Ca2+ sensors. Since that time, there has been rapid progress in our understanding of the key functions for Ca2+ in many cell types and the impact of cellular localization on Ca2+ signaling pathways. In this review, which focuses on mammalian egg activation, we consider how Ca2+ is regulated and stored at different stages of oocyte development and examine the functions of molecules that serve as both regulators of Ca2+ release and effectors of Ca2+ signals. We then summarize studies exploring how Ca2+ directs downstream effectors mediating both egg activation and later signaling events required for successful preimplantation embryo development. Throughout this review, we focus attention on how localization of Ca2+ signals influences downstream signaling events, and attempt to highlight gaps in our knowledge that are ripe areas for future research. PMID:22888043

  5. Hyperactivated Wnt signaling induces synthetic lethal interaction with Rb inactivation by elevating TORC1 activities.

    PubMed

    Zhang, Tianyi; Liao, Yang; Hsu, Fu-Ning; Zhang, Robin; Searle, Jennifer S; Pei, Xun; Li, Xuan; Ryoo, Hyung Don; Ji, Jun-Yuan; Du, Wei

    2014-05-01

    Inactivation of the Rb tumor suppressor can lead to increased cell proliferation or cell death depending on specific cellular context. Therefore, identification of the interacting pathways that modulate the effect of Rb loss will provide novel insights into the roles of Rb in cancer development and promote new therapeutic strategies. Here, we identify a novel synthetic lethal interaction between Rb inactivation and deregulated Wg/Wnt signaling through unbiased genetic screens. We show that a weak allele of axin, which deregulates Wg signaling and increases cell proliferation without obvious effects on cell fate specification, significantly alters metabolic gene expression, causes hypersensitivity to metabolic stress induced by fasting, and induces synergistic apoptosis with mutation of fly Rb ortholog, rbf. Furthermore, hyperactivation of Wg signaling by other components of the Wg pathway also induces synergistic apoptosis with rbf. We show that hyperactivated Wg signaling significantly increases TORC1 activity and induces excessive energy stress with rbf mutation. Inhibition of TORC1 activity significantly suppressed synergistic cell death induced by hyperactivated Wg signaling and rbf inactivation, which is correlated with decreased energy stress and decreased induction of apoptotic regulator expression. Finally the synthetic lethality between Rb and deregulated Wnt signaling is conserved in mammalian cells and that inactivation of Rb and APC induces synergistic cell death through a similar mechanism. These results suggest that elevated TORC1 activity and metabolic stress underpin the evolutionarily conserved synthetic lethal interaction between hyperactivated Wnt signaling and inactivated Rb tumor suppressor. PMID:24809668

  6. Activation of Akt Signaling in Prostate Induces a TGFβ Mediated Restraint on Cancer Progression and Metastasis

    PubMed Central

    Bjerke, Glen A.; Yang, Chun-Song; Frierson, Henry F.; Paschal, Bryce M.; Wotton, David

    2014-01-01

    Mutations in the PTEN tumor suppressor gene are found in a high proportion of human prostate cancers, and in mice, Pten deletion induces high-grade prostate intra-epithelial neoplasia (HGPIN). However, progression from HGPIN to invasive cancer occurs slowly, suggesting that tumorigenesis is subject to restraint. We show that Pten deletion, or constitutive activation of the downstream kinase AKT, activates the transforming growth factor (TGF) β pathway in prostate epithelial cells. TGFβ signaling is known to play a tumor suppressive role in many cancer types, and reduced expression of TGFβ receptors correlates with advanced human prostate cancer. We demonstrate that in combination either with loss of Pten, or expression of constitutively active AKT1, inactivation of TGFβ signaling by deletion of the TGFβ type II receptor gene relieves a restraint on tumorigenesis. This results in rapid progession to lethal prostate cancer, including metastasis to lymph node and lung. In prostate epithelium, inactivation of TGFβ signaling alone is insufficient to initiate tumorigenesis, but greatly accelerates cancer progression. The activation of TGFβ signaling by Pten loss or AKT activation suggests that the same signaling events that play key roles in tumor initiation also induce the activity of a pathway that restrains disease progression. PMID:23995785

  7. Activation Dynamics and Signaling Properties of Notch3 Receptor in the Developing Pulmonary Artery*

    PubMed Central

    Ghosh, Shamik; Paez-Cortez, Jesus R.; Boppidi, Karthik; Vasconcelos, Michelle; Roy, Monideepa; Cardoso, Wellington; Ai, Xingbin; Fine, Alan

    2011-01-01

    Notch3 signaling is fundamental for arterial specification of systemic vascular smooth muscle cells (VSMCs). However, the developmental role and signaling properties of the Notch3 receptor in the mouse pulmonary artery remain unknown. Here, we demonstrate that Notch3 is expressed selectively in pulmonary artery VSMCs, is activated from late fetal to early postnatal life, and is required to maintain the morphological characteristics and smooth muscle gene expression profile of the pulmonary artery after birth. Using a conditional knock-out mouse model, we show that Notch3 receptor activation in VSMCs is Jagged1-dependent. In vitro VSMC lentivirus-mediated Jagged1 knockdown, confocal localization analysis, and co-culture experiments revealed that Notch3 activation is cell-autonomous and occurs through the physical engagement of Notch3 and VSMC-derived Jagged1 in the interior of the same cell. Although the current models of mammalian Notch signaling involve a two-cell system composed of a signal-receiving cell that expresses a Notch receptor on its surface and a neighboring signal-sending cell that provides membrane-bound activating ligand, our data suggest that pulmonary artery VSMC Notch3 activation is cell-autonomous. This unique mechanism of Notch activation may play an important role in the maturation of the pulmonary artery during the transition to air breathing. PMID:21536678

  8. Carbon nanotube-assisted optical activation of TGF-β signalling by near-infrared light

    NASA Astrophysics Data System (ADS)

    Lin, Liang; Liu, Ling; Zhao, Bing; Xie, Ran; Lin, Wei; Li, He; Li, Yaya; Shi, Minlong; Chen, Ye-Guang; Springer, Timothy A.; Chen, Xing

    2015-05-01

    Receptor-mediated signal transduction modulates complex cellular behaviours such as cell growth, migration and differentiation. Although photoactivatable proteins have emerged as a powerful tool for controlling molecular interactions and signalling cascades at precise times and spaces using light, many of these light-sensitive proteins are activated by ultraviolent or visible light, which has limited tissue penetration. Here, we report a single-walled carbon nanotube (SWCNT)-assisted approach that enables near-infrared light-triggered activation of transforming growth factor β (TGF-β) signal transduction, an important signalling pathway in embryonic development and cancer progression. The protein complex of TGF-β and its latency-associated peptide is conjugated onto SWCNTs, where TGF-β is inactive. Upon near-infrared irradiation, TGF-β is released through the photothermal effect of SWCNTs and becomes active. The released TGF-β activates downstream signal transduction in live cells and modulates cellular behaviours. Furthermore, preliminary studies show that the method can be used to mediate TGF-β signalling in living mice.

  9. Carbon nanotube-assisted optical activation of TGF-β signalling by near-infrared light.

    PubMed

    Lin, Liang; Liu, Ling; Zhao, Bing; Xie, Ran; Lin, Wei; Li, He; Li, Yaya; Shi, Minlong; Chen, Ye-Guang; Springer, Timothy A; Chen, Xing

    2015-05-01

    Receptor-mediated signal transduction modulates complex cellular behaviours such as cell growth, migration and differentiation. Although photoactivatable proteins have emerged as a powerful tool for controlling molecular interactions and signalling cascades at precise times and spaces using light, many of these light-sensitive proteins are activated by ultraviolent or visible light, which has limited tissue penetration. Here, we report a single-walled carbon nanotube (SWCNT)-assisted approach that enables near-infrared light-triggered activation of transforming growth factor β (TGF-β) signal transduction, an important signalling pathway in embryonic development and cancer progression. The protein complex of TGF-β and its latency-associated peptide is conjugated onto SWCNTs, where TGF-β is inactive. Upon near-infrared irradiation, TGF-β is released through the photothermal effect of SWCNTs and becomes active. The released TGF-β activates downstream signal transduction in live cells and modulates cellular behaviours. Furthermore, preliminary studies show that the method can be used to mediate TGF-β signalling in living mice. PMID:25775150

  10. ACTIVATION OF THE EGF RECEPTOR SIGNALING PATHWAY IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO METALS

    EPA Science Inventory

    We have previously shown that exposure to combustion-derived metals rapidly (within 20 min) activated mitogen-activated protein kinases (MAPK), including extracellular signal-regulated kinase (ERK), in the human bronchial epithelial cell line BEAS. To study the mechanisms respons...

  11. Endoplasmic reticulum stress triggers ROS signalling, changes the redox state, and regulates the antioxidant defence of Arabidopsis thaliana

    PubMed Central

    Turkan, Ismail

    2014-01-01

    Inefficient chaperone activity in endoplasmic reticulum (ER) causes accumulation of unfolded proteins and is called ER stress, which triggers the unfolded protein response. For proper oxidative protein folding, reactive oxygen species (ROS) such as H2O2 are produced in the ER. Although the role of ROS during abiotic stresses such as salinity is well documented, the role of ER-related ROS production and its signalling is not yet known. Moreover, how H2O2 production, redox regulation, and antioxidant defence are affected in salt-treated plants when ER protein-folding machinery is impaired needs to be elucidated. For this aim, changes in NADPH-oxidase-dependent ROS signalling and H2O2 content at sequential time intervals and after 48h of ER stress, induced by tunicamycin (Tm), salinity, and their combination were determined in Arabidopsis thaliana. The main root growth was inhibited by ER stress, while low levels of Tm caused an increase in lateral root density. Salt stress and Tm induced the expression of ER-stress-related genes (bZIP17, bZIP28, bZIP60, TIN1, BiP1, BiP3) and ERO1. Tm induced expression of RBOHD and RBOHF, which led to an early increase in H2O2 and triggered ROS signalling. This study is the first report that ER stress induces the antioxidant system and the Asada–Halliwell pathway of A. thaliana in a similar way to salinity. ER stress caused oxidative damage, as evident by increased H2O2 accumulation, lipid peroxidation, and protein oxidation. As a result, this study shows that ER stress triggers ROS signalling, changes the redox state, and regulates the antioxidant defence of A. thaliana. PMID:24558072

  12. Presynaptic spinophilin tunes neurexin signalling to control active zone architecture and function

    PubMed Central

    Muhammad, Karzan; Reddy-Alla, Suneel; Driller, Jan H; Schreiner, Dietmar; Rey, Ulises; Böhme, Mathias A.; Hollmann, Christina; Ramesh, Niraja; Depner, Harald; Lützkendorf, Janine; Matkovic, Tanja; Götz, Torsten; Bergeron, Dominique D.; Schmoranzer, Jan; Goettfert, Fabian; Holt, Mathew; Wahl, Markus C.; Hell, Stefan W.; Scheiffele, Peter; Walter, Alexander M.; Loll, Bernhard; Sigrist, Stephan J.

    2015-01-01

    Assembly and maturation of synapses at the Drosophila neuromuscular junction (NMJ) depend on trans-synaptic neurexin/neuroligin signalling, which is promoted by the scaffolding protein Syd-1 binding to neurexin. Here we report that the scaffold protein spinophilin binds to the C-terminal portion of neurexin and is needed to limit neurexin/neuroligin signalling by acting antagonistic to Syd-1. Loss of presynaptic spinophilin results in the formation of excess, but atypically small active zones. Neuroligin-1/neurexin-1/Syd-1 levels are increased at spinophilin mutant NMJs, and removal of single copies of the neurexin-1, Syd-1 or neuroligin-1 genes suppresses the spinophilin-active zone phenotype. Evoked transmission is strongly reduced at spinophilin terminals, owing to a severely reduced release probability at individual active zones. We conclude that presynaptic spinophilin fine-tunes neurexin/neuroligin signalling to control active zone number and functionality, thereby optimizing them for action potential-induced exocytosis. PMID:26471740

  13. B cell activation involves nanoscale receptor reorganizations and inside-out signaling by Syk

    PubMed Central

    Kläsener, Kathrin; Maity, Palash C; Hobeika, Elias; Yang, Jianying; Reth, Michael

    2014-01-01

    Binding of antigen to the B cell antigen receptor (BCR) initiates a multitude of events resulting in B cell activation. How the BCR becomes signaling-competent upon antigen binding is still a matter of controversy. Using a high-resolution proximity ligation assay (PLA) to monitor the conformation of the BCR and its interactions with co-receptors at a 10–20 nm resolution, we provide direct evidence for the opening of BCR dimers during B cell activation. We also show that upon binding Syk opens the receptor by an inside-out signaling mechanism that amplifies BCR signaling. Furthermore, we found that on resting B cells, the coreceptor CD19 is in close proximity with the IgD-BCR and on activated B cells with the IgM-BCR, indicating nanoscale reorganization of receptor clusters during B cell activation. DOI: http://dx.doi.org/10.7554/eLife.02069.001 PMID:24963139

  14. Presynaptic spinophilin tunes neurexin signalling to control active zone architecture and function.

    PubMed

    Muhammad, Karzan; Reddy-Alla, Suneel; Driller, Jan H; Schreiner, Dietmar; Rey, Ulises; Böhme, Mathias A; Hollmann, Christina; Ramesh, Niraja; Depner, Harald; Lützkendorf, Janine; Matkovic, Tanja; Götz, Torsten; Bergeron, Dominique D; Schmoranzer, Jan; Goettfert, Fabian; Holt, Mathew; Wahl, Markus C; Hell, Stefan W; Scheiffele, Peter; Walter, Alexander M; Loll, Bernhard; Sigrist, Stephan J

    2015-01-01

    Assembly and maturation of synapses at the Drosophila neuromuscular junction (NMJ) depend on trans-synaptic neurexin/neuroligin signalling, which is promoted by the scaffolding protein Syd-1 binding to neurexin. Here we report that the scaffold protein spinophilin binds to the C-terminal portion of neurexin and is needed to limit neurexin/neuroligin signalling by acting antagonistic to Syd-1. Loss of presynaptic spinophilin results in the formation of excess, but atypically small active zones. Neuroligin-1/neurexin-1/Syd-1 levels are increased at spinophilin mutant NMJs, and removal of single copies of the neurexin-1, Syd-1 or neuroligin-1 genes suppresses the spinophilin-active zone phenotype. Evoked transmission is strongly reduced at spinophilin terminals, owing to a severely reduced release probability at individual active zones. We conclude that presynaptic spinophilin fine-tunes neurexin/neuroligin signalling to control active zone number and functionality, thereby optimizing them for action potential-induced exocytosis. PMID:26471740

  15. The regulation and function of the striated muscle activator of rho signaling (STARS) protein

    PubMed Central

    Wallace, Marita A.; Lamon, Séverine; Russell, Aaron P.

    2012-01-01

    Healthy living throughout the lifespan requires continual growth and repair of cardiac, smooth, and skeletal muscle. To effectively maintain these processes muscle cells detect extracellular stress signals and efficiently transmit them to activate appropriate intracellular transcriptional programs. The striated muscle activator of Rho signaling (STARS) protein, also known as Myocyte Stress-1 (MS1) protein and Actin-binding Rho-activating protein (ABRA) is highly enriched in cardiac, skeletal, and smooth muscle. STARS binds actin, co-localizes to the sarcomere and is able to stabilize the actin cytoskeleton. By regulating actin polymerization, STARS also controls an intracellular signaling cascade that stimulates the serum response factor (SRF) transcriptional pathway; a pathway controlling genes involved in muscle cell proliferation, differentiation, and growth. Understanding the activation, transcriptional control and biological roles of STARS in cardiac, smooth, and skeletal muscle, will improve our understanding of physiological and pathophysiological muscle development and function. PMID:23248604

  16. Pituitary Adenylate Cyclase-activating Polypeptide (PACAP)/PAC1HOP1 Receptor Activation Coordinates Multiple Neurotrophic Signaling Pathways

    PubMed Central

    May, Victor; Lutz, Eve; MacKenzie, Christopher; Schutz, Kristin C.; Dozark, Kate; Braas, Karen M.

    2010-01-01

    MAPK and Akt pathways are predominant mediators of trophic signaling for many neuronal systems. Among the vasoactive intestinal peptide/secretin/glucagon family of related peptides, pituitary adenylate cyclase-activating polypeptide (PACAP) binding to specific PAC1 receptor isoforms can engage multiple signaling pathways and promote neuroprotection through mechanisms that are not well understood. Using a primary sympathetic neuronal system, the current studies demonstrate that PACAP activation of PAC1HOP1 receptors engages both MAPK and Akt neurotrophic pathways in an integrated program to facilitate neuronal survival after growth factor withdrawal. PACAP not only stimulated prosurvival ERK1/2 and ERK5 activation but also abrogated SAPK/JNK and p38 MAPK signaling in parallel. In contrast to the potent and rapid effects of PACAP in ERK1/2 phosphorylation, PACAP stimulated Akt phosphorylation in a late phase of PAC1HOP1 receptor signaling. From inhibitor and immunoprecipitation analyses, the PACAP/PAC1HOP1 receptor-mediated Akt responses did not represent transactivation mechanisms but appeared to depend on Gαq/phosphatidylinositol 3-kinase γ activity and vesicular internalization pathways. Phosphatidylinositol 3-kinase γ-selective inhibitors blocked PACAP-stimulated Akt phosphorylation in primary neuronal cultures and in PAC1HOP1-overexpressing cell lines; RNA interference-mediated knockdown of the receptor effectors attenuated PACAP-mediated Akt activation. Similarly, perturbation of endocytic pathways also blocked Akt phosphorylation. Between ERK and Akt pathways, PACAP-stimulated Akt signaling was the primary cascade that attenuated cultured neuron apoptosis after growth factor withdrawal. The partitioning of PACAP-mediated Akt signaling in endosomes may be a key mechanism contributing to the high spatial and temporal specificity in signal transduction necessary for survival pathways. PMID:20093365

  17. Supramolecular organizing centers (SMOCs) as signaling machines in innate immune activation

    PubMed Central

    Qi, QIAO; Hao, WU

    2016-01-01

    Innate immunity offers the first line of defense against infections and other types of danger such as tumorigenesis. Its discovery provides tremendous therapeutic opportunities for numerous human diseases. Delving into the structural basis of signal transduction by innate immune receptors, our lab has recently helped to establish the new paradigm in which innate immune receptors transduce ligand-binding signals through formation of higher-order assemblies containing intracellular adapters, signaling enzymes and their substrates. These large signalosome assemblies may be visible under light microscopy as punctate structures in the μm scale, connecting to the underlying molecular structures in the nm scale. They drive proximity-induced enzyme activation, and provide a mechanism for signaling amplification by nucleated polymerization. These supramolecular signaling complexes also open new questions on their cellular organization and mode of regulation, pose challenges to our methodology, and afford valuable implications in drug discovery against these medically important pathways. PMID:26511517

  18. Supramolecular organizing centers (SMOCs) as signaling machines in innate immune activation.

    PubMed

    Qiao, Qi; Wu, Hao

    2015-11-01

    Innate immunity offers the first line of defense against infections and other types of danger such as tumorigenesis. Its discovery provides tremendous therapeutic opportunities for numerous human diseases. Delving into the structural basis of signal transduction by innate immune receptors, our lab has recently helped to establish the new paradigm in which innate immune receptors transduce ligand-binding signals through formation of higher-order assemblies containing intracellular adapters, signaling enzymes and their substrates. These large signalosome assemblies may be visible under light microscopy as punctate structures in the µm scale, connecting to the underlying molecular structures in the nm scale. They drive proximity-induced enzyme activation, and provide a mechanism for signaling amplification by nucleated polymerization. These supramolecular signaling complexes also open new questions on their cellular organization and mode of regulation, pose challenges to our methodology, and afford valuable implications in drug discovery against these medically important pathways. PMID:26511517

  19. Observed multivariable signals of late 20th and early 21st century volcanic activity

    NASA Astrophysics Data System (ADS)

    Santer, Benjamin D.; Solomon, Susan; Bonfils, Céline; Zelinka, Mark D.; Painter, Jeffrey F.; Beltran, Francisco; Fyfe, John C.; Johannesson, Gardar; Mears, Carl; Ridley, David A.; Vernier, Jean-Paul; Wentz, Frank J.

    2015-01-01

    The relatively muted warming of the surface and lower troposphere since 1998 has attracted considerable attention. One contributory factor to this "warming hiatus" is an increase in volcanically induced cooling over the early 21st century. Here we identify the signals of late 20th and early 21st century volcanic activity in multiple observed climate variables. Volcanic signals are statistically discernible in spatial averages of tropical and near-global SST, tropospheric temperature, net clear-sky short-wave radiation, and atmospheric water vapor. Signals of late 20th and early 21st century volcanic eruptions are also detectable in near-global averages of rainfall. In tropical average rainfall, however, only a Pinatubo-caused drying signal is identifiable. Successful volcanic signal detection is critically dependent on removal of variability induced by the El Niño-Southern Oscillation.

  20. Fluorescence/bioluminescence resonance energy transfer techniques to study G-protein-coupled receptor activation and signaling.

    PubMed

    Lohse, Martin J; Nuber, Susanne; Hoffmann, Carsten

    2012-04-01

    Fluorescence and bioluminescence resonance energy transfer (FRET and BRET) techniques allow the sensitive monitoring of distances between two labels at the nanometer scale. Depending on the placement of the labels, this permits the analysis of conformational changes within a single protein (for example of a receptor) or the monitoring of protein-protein interactions (for example, between receptors and G-protein subunits). Over the past decade, numerous such techniques have been developed to monitor the activation and signaling of G-protein-coupled receptors (GPCRs) in both the purified, reconstituted state and in intact cells. These techniques span the entire spectrum from ligand binding to the receptors down to intracellular second messengers. They allow the determination and the visualization of signaling processes with high temporal and spatial resolution. With these techniques, it has been demonstrated that GPCR signals may show spatial and temporal patterning. In particular, evidence has been provided for spatial compartmentalization of GPCRs and their signals in intact cells and for distinct physiological consequences of such spatial patterning. We review here the FRET and BRET technologies that have been developed for G-protein-coupled receptors and their signaling proteins (G-proteins, effectors) and the concepts that result from such experiments. PMID:22407612

  1. A simple geometrical description of the TrueFISP ideal transient and steady-state signal.

    PubMed

    Schmitt, P; Griswold, M A; Gulani, V; Haase, A; Flentje, M; Jakob, P M

    2006-01-01

    An intuitive approach is presented for assessment of the TrueFISP signal behavior in the transient phase and the steady state, based on geometrical considerations in combination with the Bloch equations. Short formulations are derived for the zenith and phase angle determining the direction of the magnetization vector for which a smooth monoexponential decay is obtained even at considerable off-resonance frequencies, thus compactly defining the target of various preparation schemes proposed in literature. A pictorial explanation is provided to illustrate how the interplay between RF excitation and relaxation governs the TrueFISP transient phase and steady state. Closed form expressions are developed that describe the signal evolution, accounting for the influence of T(1), T(2), flip angle, and resonance frequency offset in agreement with recently published studies. These results are obtained directly from basic assumptions, without the need for abstract mathematical treatment or further approximations. The validity of the conceptual framework and the analytical description is verified by simulations based on the Bloch equations as well as with MR phantom experiments. The theory may be used for contrast calculations and has the potential to facilitate improved parameter quantification with magnetization prepared TrueFISP experiments accounting for off-resonance effects. PMID:16323155

  2. The Mitogen-Activated Protein Kinase (MAPK) Signaling Pathway as a Discovery Target in Stroke.

    PubMed

    Sun, Jing; Nan, Guangxian

    2016-05-01

    Protein kinases are critical modulators of a variety of intracellular and extracellular signal transduction pathways, and abnormal phosphorylation events can contribute to disease progression in a variety of diseases. As a result, protein kinases have emerged as important new drug targets for small molecule therapeutics. The mitogen-activated protein kinase (MAPK) signaling pathway transmits signals from the cell membrane to the nucleus in response to a variety of different stimuli. Because this pathway controls a broad spectrum of cellular processes, including growth, inflammation, and stress responses, it is accepted as a therapeutic target for cancer and peripheral inflammatory disorders. There is also increasing evidence that MAPK is an important regulator of ischemic and hemorrhagic cerebral vascular disease, raising the possibility that it might be a drug discovery target for stroke. In this review, we discuss the MAPK signaling pathway in association with its activation in stroke-induced brain injury. PMID:26842916

  3. Extraction of motion strength and motor activity signals from video recordings of neonatal seizures.

    PubMed

    Karayiannis, N B; Srinivasan, S; Bhattacharya, R; Wise, M S; Frost, J D; Mizrahi, E M

    2001-09-01

    This paper presents two methods developed to extract quantitative information from video recordings of neonatal seizures in the form of temporal motion strength and motor activity signals. Motion strength signals are extracted by measuring the area of the body parts that move during the seizure and the relative speed of motion using a combination of spatiotemporal subband decomposition of video, nonlinear filtering, and segmentation. Motor activity signals are extracted by tracking selected anatomical sites during the seizure using a modified version of a feature-tracking procedure developed for video, known as the Kanade-Lucas-Tomasi (KLT) algorithm. The experiments indicate that the temporal signals produced by the proposed methods provide the basis for differentiating myoclonic from focal clonic seizures and distinguishing these types of neonatal seizures from normal infant behaviors. PMID:11585212

  4. miR-302 Attenuates Amyloid-β-Induced Neurotoxicity through Activation of Akt Signaling.

    PubMed

    Li, Hsin-Hua; Lin, Shi-Lung; Huang, Chien-Ning; Lu, Fung-Jou; Chiu, Pai-Yi; Huang, Wen-Nung; Lai, Te-Jen; Lin, Chih-Li

    2016-01-01

    Deficiency of insulin signaling has been linked to diabetes and ageing-related neurodegenerative diseases such as Alzheimer's disease (AD). In this regard, brains exhibit defective insulin receptor substrate-1 (IRS-1) and hence result in alteration of insulin signaling in progression of AD, the most common cause of dementia. Consequently, dysregulation of insulin signaling plays an important role in amyloid-β (Aβ)-induced neurotoxicity. As the derivation of induced pluripotent stem cells (iPSC) involves cell reprogramming, it may provide a means for regaining the control of ageing-associated dysfunction and neurodegeneration via affecting insulin-related signaling. To this, we found that an embryonic stem cell (ESC)-specific microRNA, miR-302, silences phosphatase and tensin homolog (PTEN) to activate Akt signaling, which subsequently stimulates nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) elevation and hence inhibits Aβ-induced neurotoxicity. miR-302 is predominantly expressed in iPSCs and is known to regulate several important biological processes of anti-oxidative stress, anti-apoptosis, and anti-aging through activating Akt signaling. In addition, we also found that miR-302-mediated Akt signaling further stimulates Nanog expression to suppress Aβ-induced p-Ser307 IRS-1 expression and thus enhances tyrosine phosphorylation and p-Ser 473-Akt/p-Ser 9-GSK3β formation. Furthermore, our in vivo studies revealed that the mRNA expression levels of both Nanog and miR-302-encoding LARP7 genes were significantly reduced in AD patients' blood cells, providing a novel diagnosis marker for AD. Taken together, our findings demonstrated that miR-302 is able to inhibit Aβ-induced cytotoxicity via activating Akt signaling to upregulate Nrf2 and Nanog expressions, leading to a marked restoration of insulin signaling in AD neurons. PMID:26890744

  5. Integrin-Dependent Activation of the JNK Signaling Pathway by Mechanical Stress

    PubMed Central

    Kanger, Johannes S.; Subramaniam, Vinod; Martin-Blanco, Enrique

    2011-01-01

    Mechanical force is known to modulate the activity of the Jun N-terminal kinase (JNK) signaling cascade. However, the effect of mechanical stresses on JNK signaling activation has previously only been analyzed by in vitro detection methods. It still remains unknown how living cells activate the JNK signaling cascade in response to mechanical stress and what its functions are in stretched cells. We assessed in real-time the activity of the JNK pathway in Drosophila cells by Fluorescence Lifetime Imaging Microscopy (FLIM), using an intramolecular phosphorylation-dependent dJun-FRET (Fluorescence Resonance Energy Transfer) biosensor. We found that quantitative FRET-FLIM analysis and confocal microscopy revealed sustained dJun-FRET biosensor activation and stable morphology changes in response to mechanical stretch for Drosophila S2R+ cells. Further, these cells plated on different substrates showed distinct levels of JNK activity that associate with differences in cell morphology, integrin expression and focal adhesion organization. These data imply that alterations in the cytoskeleton and matrix attachments may act as regulators of JNK signaling, and that JNK activity might feed back to modulate the cytoskeleton and cell adhesion. We found that this dynamic system is highly plastic; at rest, integrins at focal adhesions and talin are key factors suppressing JNK activity, while multidirectional static stretch leads to integrin-dependent, and probably talin-independent, Jun sensor activation. Further, our data suggest that JNK activity has to coordinate with other signaling elements for the regulation of the cytoskeleton and cell shape remodeling associated with stretch. PMID:22180774

  6. State opportunities for action: Update of states' combined heat and power activities

    SciTech Connect

    Brown, Elizabeth; Elliott, R. Neal

    2003-10-01

    This report updates the review of state policies with regard to CHP that the American Council for and Energy Efficient Economy completed in 2002. It describes the current activities of states with programs during the initial survey and also reviews new programs offered by the states.

  7. 34 CFR 403.70 - How must funds be used under the State Programs and State Leadership Activities?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... State Leadership Activities? 403.70 Section 403.70 Education Regulations of the Offices of the... the Basic Programs? State Programs and State Leadership Activities § 403.70 How must funds be used under the State Programs and State Leadership Activities? A State shall use funds reserved under...

  8. 34 CFR 403.70 - How must funds be used under the State Programs and State Leadership Activities?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... State Leadership Activities? 403.70 Section 403.70 Education Regulations of the Offices of the... the Basic Programs? State Programs and State Leadership Activities § 403.70 How must funds be used under the State Programs and State Leadership Activities? A State shall use funds reserved under...

  9. 34 CFR 403.70 - How must funds be used under the State Programs and State Leadership Activities?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... State Leadership Activities? 403.70 Section 403.70 Education Regulations of the Offices of the... the Basic Programs? State Programs and State Leadership Activities § 403.70 How must funds be used under the State Programs and State Leadership Activities? A State shall use funds reserved under...

  10. 34 CFR 403.70 - How must funds be used under the State Programs and State Leadership Activities?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... State Leadership Activities? 403.70 Section 403.70 Education Regulations of the Offices of the... the Basic Programs? State Programs and State Leadership Activities § 403.70 How must funds be used under the State Programs and State Leadership Activities? A State shall use funds reserved under...

  11. Evaluation of the effect of signalment and body conformation on activity monitoring in companion dogs

    PubMed Central

    Brown, Dorothy Cimino; Michel, Kathryn E.; Love, Molly; Dow, Caitlin

    2015-01-01

    Objective To evaluate the effect of signalment and body conformation on activity monitoring in companion dogs. Animals 104 companion dogs. Procedures While wearing an activity monitor, each dog was led through a series of standard activities: lying down, walking laps, trotting laps, and trotting up and down stairs. Linear regression analysis was used to determine which signalment and body conformation factors were associated with activity counts. Results There was no significant effect of signalment or body conformation on activity counts when dogs were lying down, walking laps, and trotting laps. However, when dogs were trotting up and down stairs, there was a significant effect of age and body weight such that, for every 1-kg increase in body weight, there was a 1.7% (95% confidence interval, 1.1% to 2.4%) decrease in activity counts and for every 1-year increase in age, there was a 4.2% (95% confidence interval, 1.4% to 6.9%) decrease in activity counts. Conclusions and Clinical Relevance When activity was well controlled, there was no significant effect of signalment or body conformation on activity counts recorded by the activity monitor. However, when activity was less controlled, older dogs and larger dogs had lower activity counts than younger and smaller dogs. The wide range in body conformation (eg, limb or body length) among dogs did not appear to significantly impact the activity counts recorded by the monitor, but age and body weight did and must be considered in analysis of data collected from the monitors. PMID:20187834

  12. Biased signalling from the glucocorticoid receptor: Renewed opportunity for tailoring glucocorticoid activity.

    PubMed

    Keenan, Christine R; Lew, Michael J; Stewart, Alastair G

    2016-07-15

    Recent landmark studies applying analytical pharmacology approaches to the glucocorticoid receptor (GR) have demonstrated that different ligands can cause differential activation of distinct GR-regulated genes. Drawing on concepts of signalling bias from the field of G protein-coupled receptor (GPCR) biology, we speculate that ligand-dependent differences in GR signalling can be considered analogous to GPCR biased signalling, and thus can be quantitatively analysed in a similar way. This type of approach opens up the possibility of using rational structure-based drug optimisation strategies to improve the therapeutic selectivity of glucocorticoid drugs to maximise their efficacy and minimise adverse effects. PMID:26898958

  13. The functional activity of hypothalamic signaling systems in rats with neonatal diabetes mellitus treated with metformin.

    PubMed

    Derkach, K V; Sukhov, I B; Kuznetsova, L A; Buzanakov, D M; Shpakov, A O

    2016-03-01

    The effect of the two-month metformin treatment (200 mg/kg/day) of rats with the neonatal model of type 2 diabetes mellitus on the functional activity of hypothalamic signaling systems was studied. It was shown that metformin treatment restored the sensitivity of hypothalamic adenylyl cyclase signaling system to agonists of the type 4 melanocortin receptor and the type 2 dopamine receptor but did not influence significantly the functions of the insulin signaling system. These data suggest new targets and mechanisms of metformin action in the CNS, which may mediate its restoring effect on energy homeostasis impaired in diabetic pathology. PMID:27193707

  14. A Gaussian process framework for modelling stellar activity signals in radial velocity data

    NASA Astrophysics Data System (ADS)

    Rajpaul, V.; Aigrain, S.; Osborne, M. A.; Reece, S.; Roberts, S.

    2015-09-01

    To date, the radial velocity (RV) method has been one of the most productive techniques for detecting and confirming extrasolar planetary candidates. Unfortunately, stellar activity can induce RV variations which can drown out or even mimic planetary signals - and it is notoriously difficult to model and thus mitigate the effects of these activity-induced nuisance signals. This is expected to be a major obstacle to using next-generation spectrographs to detect lower mass planets, planets with longer periods, and planets around more active stars. Enter Gaussian processes (GPs) which, we note, have a number of attractive features that make them very well suited to disentangling stellar activity signals from planetary signals. We present here a GP framework we developed to model RV time series jointly with ancillary activity indicators (e.g. bisector velocity spans, line widths, chromospheric activity indices), allowing the activity component of RV time series to be constrained and disentangled from e.g. planetary components. We discuss the mathematical details of our GP framework, and present results illustrating its encouraging performance on both synthetic and real RV data sets, including the publicly available Alpha Centauri B data set.

  15. Fn14, a Downstream Target of the TGF-β Signaling Pathway, Regulates Fibroblast Activation

    PubMed Central

    Yang, Min; Lai, Wen; Ye, Litong; Chen, Jing; Hou, Xinghua; Ding, Hong; Zhang, Wenwei; Wu, Yueheng; Liu, Xiaoying; Huang, Shufang; Yu, Xiyong; Xiao, Dingzhang

    2015-01-01

    Fibrosis, the hallmark of human injuries and diseases such as serious burns, is characterized by excessive collagen synthesis and myofibroblast accumulation. Transforming growth factor-β (TGF-β), a potent inducer of collagen synthesis, has been implicated in fibrosis in animals. In addition to TGF-β, fibroblast growth factor-inducible molecule 14 (Fn14) has been reported to play an important role in fibrotic diseases, such as cardiac fibrosis. However, the function and detailed regulatory mechanism of Fn14 in fibrosis are unclear. Here, we investigated the effect of Fn14 on the activation of human dermal fibroblasts. In normal dermal fibroblasts, TGF-β signaling increased collagen production and Fn14 expression. Furthermore, Fn14 siRNA blocked extracellular matrix gene expression; even when TGF-β signaling was activated by TGF-β1, fibroblast activation remained blocked in the presence of Fn14 siRNA. Overexpressing Fn14 increased extracellular matrix gene expression. In determining the molecular regulatory mechanism, we discovered that SMAD4, an important TGF-β signaling co-mediator, bound to the Fn14 promoter and activated Fn14 transcription. Taken together, these results indicate that the TGF-β signaling pathway activates Fn14 expression through the transcription factor SMAD4 and that activated Fn14 expression increases extracellular matrix synthesis and fibroblast activation. Therefore, Fn14 may represent a promising approach to preventing the excessive accumulation of collagen or ECM in skin fibrosis. PMID:26625141

  16. Subcellular optogenetic activation of Cdc42 controls local and distal signaling to drive immune cell migration

    PubMed Central

    O’Neill, Patrick R.; Kalyanaraman, Vani; Gautam, N.

    2016-01-01

    Migratory immune cells use intracellular signaling networks to generate and orient spatially polarized responses to extracellular cues. The monomeric G protein Cdc42 is believed to play an important role in controlling the polarized responses, but it has been difficult to determine directly the consequences of localized Cdc42 activation within an immune cell. Here we used subcellular optogenetics to determine how Cdc42 activation at one side of a cell affects both cell behavior and dynamic molecular responses throughout the cell. We found that localized Cdc42 activation is sufficient to generate polarized signaling and directional cell migration. The optically activated region becomes the leading edge of the cell, with Cdc42 activating Rac and generating membrane protrusions driven by the actin cytoskeleton. Cdc42 also exerts long-range effects that cause myosin accumulation at the opposite side of the cell and actomyosin-mediated retraction of the cell rear. This process requires the RhoA-activated kinase ROCK, suggesting that Cdc42 activation at one side of a cell triggers increased RhoA signaling at the opposite side. Our results demonstrate how dynamic, subcellular perturbation of an individual signaling protein can help to determine its role in controlling polarized cellular responses. PMID:26941336

  17. Subcellular optogenetic activation of Cdc42 controls local and distal signaling to drive immune cell migration.

    PubMed

    O'Neill, Patrick R; Kalyanaraman, Vani; Gautam, N

    2016-05-01

    Migratory immune cells use intracellular signaling networks to generate and orient spatially polarized responses to extracellular cues. The monomeric G protein Cdc42 is believed to play an important role in controlling the polarized responses, but it has been difficult to determine directly the consequences of localized Cdc42 activation within an immune cell. Here we used subcellular optogenetics to determine how Cdc42 activation at one side of a cell affects both cell behavior and dynamic molecular responses throughout the cell. We found that localized Cdc42 activation is sufficient to generate polarized signaling and directional cell migration. The optically activated region becomes the leading edge of the cell, with Cdc42 activating Rac and generating membrane protrusions driven by the actin cytoskeleton. Cdc42 also exerts long-range effects that cause myosin accumulation at the opposite side of the cell and actomyosin-mediated retraction of the cell rear. This process requires the RhoA-activated kinase ROCK, suggesting that Cdc42 activation at one side of a cell triggers increased RhoA signaling at the opposite side. Our results demonstrate how dynamic, subcellular perturbation of an individual signaling protein can help to determine its role in controlling polarized cellular responses. PMID:26941336

  18. Active Solid State Dosimetry for Lunar EVA

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Fralick, Gustave C.; Wrbanek, Susan Y.; Chen, Liang-Yu.

    2006-01-01

    The primary threat to astronauts from space radiation is high-energy charged particles, such as electrons, protons, alpha and heavier particles, originating from galactic cosmic radiation (GCR), solar particle events (SPEs) and trapped radiation belts in Earth orbit. There is also the added threat of secondary neutrons generated as the space radiation interacts with atmosphere, soil and structural materials.[1] For Lunar exploration missions, the habitats and transfer vehicles are expected to provide shielding from standard background radiation. Unfortunately, the Lunar Extravehicular Activity (EVA) suit is not expected to afford such shielding. Astronauts need to be aware of potentially hazardous conditions in their immediate area on EVA before a health and hardware risk arises. These conditions would include fluctuations of the local radiation field due to changes in the space radiation field and unknown variations in the local surface composition. Should undue exposure occur, knowledge of the dynamic intensity conditions during the exposure will allow more precise diagnostic assessment of the potential health risk to the exposed individual.[2

  19. [Nonequilibrium state of electrochemically activated water and its biological activity].

    PubMed

    Petrushanko, I Iu; Lobyshev, V I

    2001-01-01

    Changes in the physicochemical parameters (pH, redox potential and electroconductivity) of catholyte and anolyte produced by membrane electrolysis of distilled water and dilute (c < 10(-3) M) sodium chloride solutions were studied. The relaxation of these parameters after electrolysis and the influence of catholyte and anolyte on the growth of roots of Tradescantia viridis grafts, the development of duckweed, and the motive activity of infusoria Spirostomum ambiguum were investigated. It was found that the anolyte of distilled water stimulated development of these biological objects. The direction of shift of physicochemical parameters of catholyte and anolyte from equilibrium values and the type of their biological activity (stimulation or inhibition) depend on salt concentration in initial solution. Barbotage of initial distilled water with argon or nitrogen leads to a greater decrease in the redox potential of catholyte during electrolysis. The physicochemical parameters relax to equilibrium values, and the biological activity of catholite and anolyte decreases with time and practically disappears by the end of the day. It was found that the oxidation of reducing agent by atmospheric oxygen is not the sole cause of the relaxation of catalyte redox potential. The increase in the ionic strength of catholite and anolyte by the addition of concentrated sodium chloride after electrolysis decreases the rate of redox potential relaxation several times. The redox potential can be maintained for long periods by freezing. PMID:11449536

  20. Metastable primordial germ cell-like state induced from mouse embryonic stem cells by Akt activation

    SciTech Connect

    Yamano, Noriko; Kimura, Tohru; Watanabe-Kushima, Shoko; Shinohara, Takashi; Nakano, Toru

    2010-02-12

    Specification to primordial germ cells (PGCs) is mediated by mesoderm-induction signals during gastrulation. We found that Akt activation during in vitro mesodermal differentiation of embryonic stem cells (ESCs) generated self-renewing spheres with differentiation states between those of ESCs and PGCs. Essential regulators for PGC specification and their downstream germ cell-specific genes were expressed in the spheres, indicating that the sphere cells had commenced differentiation to the germ lineage. However, the spheres did not proceed to spermatogenesis after transplantation into testes. Sphere cell transfer to the original feeder-free ESC cultures resulted in chaotic differentiation. In contrast, when the spheres were cultured on mouse embryonic fibroblasts or in the presence of ERK-cascade and GSK3 inhibitors, reversion to the ESC-like state was observed. These results indicate that Akt signaling promotes a novel metastable and pluripotent state that is intermediate to those of ESCs and PGCs.

  1. Intrinsic Brain Activity in Altered States of Consciousness

    PubMed Central

    Boly, M.; Phillips, C.; Tshibanda, L.; Vanhaudenhuyse, A.; Schabus, M.; Dang-Vu, T.T.; Moonen, G.; Hustinx, R.; Maquet, P.; Laureys, S.

    2010-01-01

    Spontaneous brain activity has recently received increasing interest in the neuroimaging community. However, the value of resting-state studies to a better understanding of brain–behavior relationships has been challenged. That altered states of consciousness are a privileged way to study the relationships between spontaneous brain activity and behavior is proposed, and common resting-state brain activity features observed in various states of altered consciousness are reviewed. Early positron emission tomography studies showed that states of extremely low or high brain activity are often associated with unconsciousness. However, this relationship is not absolute, and the precise link between global brain metabolism and awareness remains yet difficult to assert. In contrast, voxel-based analyses identified a systematic impairment of associative frontoparieto–cingulate areas in altered states of consciousness, such as sleep, anesthesia, coma, vegetative state, epileptic loss of consciousness, and somnambulism. In parallel, recent functional magnetic resonance imaging studies have identified structured patterns of slow neuronal oscillations in the resting human brain. Similar coherent blood oxygen level–dependent (BOLD) systemwide patterns can also be found, in particular in the default-mode network, in several states of unconsciousness, such as coma, anesthesia, and slow-wave sleep. The latter results suggest that slow coherent spontaneous BOLD fluctuations cannot be exclusively a reflection of conscious mental activity, but may reflect default brain connectivity shaping brain areas of most likely interactions in a way that transcends levels of consciousness, and whose functional significance remains largely in the dark. PMID:18591474

  2. Recombinant TCR ligand induces early TCR signaling and a unique pattern of downstream activation.

    PubMed

    Wang, Chunhe; Mooney, Jeffery L; Meza-Romero, Roberto; Chou, Yuan K; Huan, Jianya; Vandenbark, Arthur A; Offner, Halina; Burrows, Gregory G

    2003-08-15

    Recombinant TCR ligands (RTLs) consisting of covalently linked alpha(1) and beta(1) domains of MHC class II molecules tethered to specific antigenic peptides represent minimal TCR ligands. In a previous study we reported that the rat RTL201 construct, containing RT1.B MHC class II domains covalently coupled to the encephalitogenic guinea pig myelin basic protein (Gp-MBP(72-89)) peptide, could prevent and treat actively and passively induced experimental autoimmune encephalomyelitis in vivo by selectively inhibiting Gp-MBP(72-89) peptide-specific CD4(+) T cells. To evaluate the inhibitory signaling pathway, we tested the effects of immobilized RTL201 on T cell activation of the Gp-MBP(72-89)-specific A1 T cell hybridoma. Activation was exquisitely Ag-specific and could not be induced by RTL200 containing the rat MBP(72-89) peptide that differed by a threonine for serine substitution at position 80. Partial activation by RTL201 included a CD3zeta p23/p21 ratio shift, ZAP-70 phosphorylation, calcium mobilization, NFAT activation, and transient IL-2 production. In comparison, anti-CD3epsilon treatment produced stronger activation of these cellular events with additional activation of NF-kappaB and extracellular signal-regulated kinases as well as long term increased IL-2 production. These results demonstrate that RTLs can bind directly to the TCR and modify T cell behavior through a partial activation mechanism, triggering specific downstream signaling events that deplete intracellular calcium stores without fully activating T cells. The resulting Ag-specific activation of the transcription factor NFAT uncoupled from the activation of NF-kappaB or extracellular signal-regulated kinases constitutes a unique downstream activation pattern that accounts for the inhibitory effects of RTL on encephalitogenic CD4(+) T cells. PMID:12902496

  3. Monitoring and predicting cognitive state and performance via physiological correlates of neuronal signals.

    PubMed

    Russo, Michael B; Stetz, Melba C; Thomas, Maria L

    2005-07-01

    Judgment, decision making, and situational awareness are higher-order mental abilities critically important to operational cognitive performance. Higher-order mental abilities rely on intact functioning of multiple brain regions, including the prefrontal, thalamus, and parietal areas. Real-time monitoring of individuals for cognitive performance capacity via an approach based on sampling multiple neurophysiologic signals and integrating those signals with performance prediction models potentially provides a method of supporting warfighters' and commanders' decision making and other operationally relevant mental processes and is consistent with the goals of augmented cognition. Cognitive neurophysiological assessments that directly measure brain function and subsequent cognition include positron emission tomography, functional magnetic resonance imaging, mass spectroscopy, near-infrared spectroscopy, magnetoencephalography, and electroencephalography (EEG); however, most direct measures are not practical to use in operational environments. More practical, albeit indirect measures that are generated by, but removed from the actual neural sources, are movement activity, oculometrics, heart rate, and voice stress signals. The goal of the papers in this section is to describe advances in selected direct and indirect cognitive neurophysiologic monitoring techniques as applied for the ultimate purpose of preventing operational performance failures. These papers present data acquired in a wide variety of environments, including laboratory, simulator, and clinical arenas. The papers discuss cognitive neurophysiologic measures such as digital signal processing wrist-mounted actigraphy; oculometrics including blinks, saccadic eye movements, pupillary movements, the pupil light reflex; and high-frequency EEG. These neurophysiological indices are related to cognitive performance as measured through standard test batteries and simulators with conditions including sleep loss

  4. Fatty acid-induced NLRP3-PYCARD inflammasome activation interferes with insulin signaling

    PubMed Central

    Wen, Haitao; Gris, Denis; Lei, Yu; Jha, Sushmita; Zhang, Lu; Huang, Max Tze-Han; Brickey, Willie June; Ting, Jenny P.-Y.

    2014-01-01

    High-fat diet (HFD) and inflammation are key contributors to insulin resistance and type 2 diabetes (T2D). Interleukin (IL)-1β plays a role in insulin resistance; yet, how IL-1β is induced by fatty acid with HFD, and how this alters insulin signaling is unclear. We show that the saturated fatty acid, palmitate, but not unsaturated oleate, induces the activation of NLRP3-PYCARD inflammasome, causing caspase-1, IL-1β, and IL-18 production. This involves mitochondrial reactive oxygen species and the AMP-activated protein kinase and ULK1 autophagy signaling cascade. Inflammasome activation in hematopoietic cells impairs insulin signaling in several target tissues to reduce glucose tolerance and insulin sensitivity. Furthermore, IL-1β affects insulin sensitivity via TNF-independent and dependent pathways. These findings provide insights into the association of inflammation, diet and T2D. PMID:21478880

  5. Phagocyte respiratory burst activates macrophage erythropoietin signalling to promote acute inflammation resolution.

    PubMed

    Luo, Bangwei; Wang, Jinsong; Liu, Zongwei; Shen, Zigang; Shi, Rongchen; Liu, Yu-Qi; Liu, Yu; Jiang, Man; Wu, Yuzhang; Zhang, Zhiren

    2016-01-01

    Inflammation resolution is an active process, the failure of which causes uncontrolled inflammation which underlies many chronic diseases. Therefore, endogenous pathways that regulate inflammation resolution are fundamental and of wide interest. Here, we demonstrate that phagocyte respiratory burst-induced hypoxia activates macrophage erythropoietin signalling to promote acute inflammation resolution. This signalling is activated following acute but not chronic inflammation. Pharmacological or genetical inhibition of the respiratory burst suppresses hypoxia and macrophage erythropoietin signalling. Macrophage-specific erythropoietin receptor-deficient mice and chronic granulomatous disease (CGD) mice, which lack the capacity for respiratory burst, display impaired inflammation resolution, and exogenous erythropoietin enhances this resolution in WT and CGD mice. Mechanistically, erythropoietin increases macrophage engulfment of apoptotic neutrophils via PPARγ, promotes macrophage removal of debris and enhances macrophage migration to draining lymph nodes. Together, our results provide evidences of an endogenous pathway that regulates inflammation resolution, with important implications for treating inflammatory conditions. PMID:27397585

  6. PAK1 is a breast cancer oncogene that coordinately activates MAPK and MET signaling

    PubMed Central

    Shrestha, Yashaswi; Schafer, Eric J.; Boehm, Jesse S.; Thomas, Sapana R.; He, Frank; Du, Jinyan; Wang, Shumei; Barretina, Jordi; Weir, Barbara A.; Zhao, Jean J.; Polyak, Kornelia; Golub, Todd R.; Beroukhim, Rameen; Hahn, William C.

    2011-01-01

    Activating mutations in the RAS family or BRAF frequently occur in many types of human cancers but are rarely detected in breast tumors. However, activation of the RAS-RAF-MEK-ERK Mitogen-Activated Protein Kinase (MAPK) pathway is commonly observed in human breast cancers, suggesting that other genetic alterations lead to activation of this signaling pathway. To identify breast cancer oncogenes that activate the MAPK pathway, we screened a library of human kinases for their ability to induce anchorage-independent growth in a derivative of immortalized human mammary epithelial cells (HMLE). We identified PAK1 as a kinase that permitted HMLE cells to form anchorage-independent colonies. PAK1 is amplified in several human cancer types, including 33% of breast tumor samples and cancer cell lines. The kinase activity of PAK1 is necessary for PAK1-induced transformation. Moreover, we show that PAK1 simultaneously activates MAPK and MET signaling; the latter via inhibition of Merlin. Disruption of these activities inhibits PAK1-driven anchorage-independent growth. These observations establish PAK1 amplification as an alternative mechanism for MAPK activation in human breast cancer and credential PAK1 as a breast cancer oncogene that coordinately regulates multiple signaling pathways, the cooperation of which leads to malignant transformation. PMID:22105362

  7. Ras-activated Dsor1 promotes Wnt signaling in Drosophila development.

    PubMed

    Hall, Eric T; Verheyen, Esther M

    2015-12-15

    Wnt/Wingless (Wg) and Ras-MAPK signaling both play fundamental roles in growth and cell fate determination, and when dysregulated, can lead to tumorigenesis. Several conflicting modes of interaction between Ras-MAPK and Wnt signaling have been identified in specific cellular contexts, causing synergistic or antagonistic effects on target genes. We find novel evidence that the Drosophila homolog of the dual specificity kinases MEK1/2 (also known as MAP2K1/2), Downstream of Raf1 (Dsor1), is required for Wnt signaling. Knockdown of Dsor1 results in loss of Wg target gene expression, as well as reductions in stabilized Armadillo (Arm; Drosophila β-catenin). We identify a close physical interaction between Dsor1 and Arm, and find that catalytically inactive Dsor1 causes a reduction in active Arm. These results suggest that Dsor1 normally counteracts the Axin-mediated destruction of Arm. We find that Ras-Dsor1 activity is independent of upstream activation by EGFR, and instead it appears to be activated by the insulin-like growth factor receptor to promote Wg signaling. Taken together, our results suggest that there is a new crosstalk pathway between insulin and Wg signaling that is mediated by Dsor1. PMID:26542023

  8. A high-content screening assay in transgenic zebrafish identifies two novel activators of fgf signaling.

    PubMed

    Saydmohammed, Manush; Vollmer, Laura L; Onuoha, Ezenwa Obi; Vogt, Andreas; Tsang, Michael

    2011-09-01

    Zebrafish have become an invaluable vertebrate animal model to interrogate small molecule libraries for modulators of complex biological pathways and phenotypes. We have recently described the implementation of a quantitative, high-content imaging assay in multi-well plates to analyze the effects of small molecules on Fibroblast Growth Factor (FGF) signaling in vivo. Here we have evaluated the capability of the assay to identify compounds that hyperactivate FGF signaling from a test cassette of agents with known biological activities. Using a transgenic zebrafish reporter line for FGF activity, we screened 1040 compounds from an annotated library of known bioactive agents, including FDA-approved drugs. The assay identified two molecules, 8-hydroxyquinoline sulfate and pyrithione zinc, that enhanced FGF signaling in specific areas of the brain. Subsequent studies revealed that both compounds specifically expanded FGF target gene expression. Furthermore, treatment of early stage embryos with either compound resulted in dorsalized phenotypes characteristic of hyperactivation of FGF signaling in early development. Documented activities for both agents included activation of extracellular signal-related kinase (ERK), consistent with FGF hyperactivation. To conclude, we demonstrate the power of automated quantitative high-content imaging to identify small molecule modulators of FGF. PMID:21932436

  9. Differential Signaling by Protease-Activated Receptors: Implications for Therapeutic Targeting

    PubMed Central

    Sidhu, Tejminder S.; French, Shauna L.; Hamilton, Justin R.

    2014-01-01

    Protease-activated receptors (PARs) are a family of four G protein-coupled receptors that exhibit increasingly appreciated differences in signaling and regulation both within and between the receptor class. By nature of their proteolytic self-activation mechanism, PARs have unique processes of receptor activation, “ligand” binding, and desensitization/resensitization. These distinctive aspects have presented both challenges and opportunities in the targeting of PARs for therapeutic benefit—the most notable example of which is inhibition of PAR1 on platelets for the prevention of arterial thrombosis. However, more recent studies have uncovered further distinguishing features of PAR-mediated signaling, revealing mechanisms by which identical proteases elicit distinct effects in the same cell, as well as how distinct proteases produce different cellular consequences via the same receptor. Here we review this differential signaling by PARs, highlight how important distinctions between PAR1 and PAR4 are impacting on the progress of a new class of anti-thrombotic drugs, and discuss how these more recent insights into PAR signaling may present further opportunities for manipulating PAR activation and signaling in the development of novel therapies. PMID:24733067

  10. Ionizing Radiation Shifts the PAI-1/ID-1 Balance and Activates Notch Signaling in Endothelial Cells

    SciTech Connect

    Scharpfenecker, Marion; Kruse, Jacqueline; Sprong, Debbie; Russell, Nicola S.; Dijke, Peter ten; Stewart, Fiona A.

    2009-02-01

    Purpose: Transforming growth factor-{beta} (TGF-{beta}) and Notch signaling pathways are important regulators of vascular homeostasis and vessel remodeling; mutations in these pathways can lead to vascular disorders. Similar vascular phenotypes develop in the normal tissues of cancer patients as a long-term effect of radiotherapy. Irradiation most severely affects the capillaries, which become leaky and dilated and might eventually rupture. To investigate the mechanism of such capillary damage, we studied the effect of TGF-{beta} and Notch signaling in microvascular endothelial cells. Methods and Materials: Human microvascular endothelial cells were irradiated with 5 or 10 Gy and activation of TGF-{beta} and Notch signaling pathways was assessed by biochemical methods and a cell migration assay. Results: Ionizing radiation induced Smad2 phosphorylation and nuclear translocation and increased mRNA and protein expression of the activin-like kinase 5 (ALK5) target gene plasminogen activator inhibitor-1 (PAI-1). At the same time, we observed diminished Smad1/5/8 activation and downregulation of the ALK1 downstream target, inhibitor of DNA binding-1 (ID-1). We also measured an upregulation of the Notch ligand Jagged-1 and the target gene Hey1. Decreased inhibitor of DNA binding-1 levels coincided with a reduced ability of the cells to migrate. Conclusion: Ionizing radiation shifts the balance from ALK1 to ALK5 signaling and activates the Notch pathway in endothelial cells. This combination of anti-angiogenic signals contributes to reduced cell migration after irradiation.

  11. A Study of Position-Sensitive Solid-State Photomultiplier Signal Properties

    PubMed Central

    Schmall, Jeffrey P.; Du, Junwei; Judenhofer, Martin S.; Dokhale, Purushottam; Christian, James; McClish, Mickel; Shah, Kanai S.; Cherry, Simon R.

    2014-01-01

    We present an analysis of the signal properties of a position-sensitive solid-state photomultiplier (PS-SSPM) that has an integrated resistive network for position sensing. Attractive features of PS-SSPMs are their large area and ability to resolve small scintillator crystals. However, the large area leads to a high detector capacitance, and in order to achieve high spatial resolution a large network resistor value is required. These inevitably create a low-pass filter that drastically slows what would be a fast micro-cell discharge pulse. Significant changes in the signal shape of the PS-SSPM cathode output as a function of position are observed, which result in a position-dependent time delay when using traditional time pick-off methods such as leading edge discrimination and constant fraction discrimination. The timing resolution and time delay, as a function of position, were characterized for two different PS-SSPM designs, a continuous 10 mm × 10 mm PS-SSPM and a tiled 2 × 2 array of 5 mm × 5 mm PS-SSPMs. After time delay correction, the block timing resolution, measured with a 6 × 6 array of 1.3 × 1.3 × 20 mm3 LSO crystals, was 8.6 ns and 8.5 ns, with the 10 mm PS-SSPM and 5 mm PS-SSPM respectively. The effect of crystal size on timing resolution was also studied, and contrary to expectation, a small improvement was measured when reducing the crystal size from 1.3 mm to 0.5 mm. Digital timing methods were studied and showed great promise for allowing accurate timing by implementation of a leading edge time pick-off. Position-dependent changes in signal shape on the anode side also are present, which complicates peak height data acquisition methods used for positioning. We studied the effect of trigger position on signal amplitude, flood histogram quality, and depth-of-interaction resolution in a dual-ended readout detector configuration. We conclude that detector timing and positioning can be significantly improved by implementation of digital timing

  12. A Study of Position-Sensitive Solid-State Photomultiplier Signal Properties.

    PubMed

    Schmall, Jeffrey P; Du, Junwei; Judenhofer, Martin S; Dokhale, Purushottam; Christian, James; McClish, Mickel; Shah, Kanai S; Cherry, Simon R

    2014-06-12

    We present an analysis of the signal properties of a position-sensitive solid-state photomultiplier (PS-SSPM) that has an integrated resistive network for position sensing. Attractive features of PS-SSPMs are their large area and ability to resolve small scintillator crystals. However, the large area leads to a high detector capacitance, and in order to achieve high spatial resolution a large network resistor value is required. These inevitably create a low-pass filter that drastically slows what would be a fast micro-cell discharge pulse. Significant changes in the signal shape of the PS-SSPM cathode output as a function of position are observed, which result in a position-dependent time delay when using traditional time pick-off methods such as leading edge discrimination and constant fraction discrimination. The timing resolution and time delay, as a function of position, were characterized for two different PS-SSPM designs, a continuous 10 mm × 10 mm PS-SSPM and a tiled 2 × 2 array of 5 mm × 5 mm PS-SSPMs. After time delay correction, the block timing resolution, measured with a 6 × 6 array of 1.3 × 1.3 × 20 mm(3) LSO crystals, was 8.6 ns and 8.5 ns, with the 10 mm PS-SSPM and 5 mm PS-SSPM respectively. The effect of crystal size on timing resolution was also studied, and contrary to expectation, a small improvement was measured when reducing the crystal size from 1.3 mm to 0.5 mm. Digital timing methods were studied and showed great promise for allowing accurate timing by implementation of a leading edge time pick-off. Position-dependent changes in signal shape on the anode side also are present, which complicates peak height data acquisition methods used for positioning. We studied the effect of trigger position on signal amplitude, flood histogram quality, and depth-of-interaction resolution in a dual-ended readout detector configuration. We conclude that detector timing and positioning can be significantly improved by implementation of digital timing

  13. Head direction cell activity in mice: robust directional signal depends on intact otolith organs.

    PubMed

    Yoder, Ryan M; Taube, Jeffrey S

    2009-01-28

    The head direction (HD) cell signal is a representation of an animal's perceived directional heading with respect to its environment. This signal appears to originate in the vestibular system, which includes the semicircular canals and otolith organs. Preliminary studies indicate the semicircular canals provide a necessary component of the HD signal, but involvement of otolithic information in the HD signal has not been tested. The present study was designed to determine the otolithic contribution to the HD signal, as well as to compare HD cell activity of mice with that of rats. HD cell activity in the anterodorsal thalamus was assessed in wild-type C57BL/6J and otoconia-deficient tilted mice during locomotion within a cylinder containing a prominent visual landmark. HD cell firing properties in C57BL/6J mice were generally similar to those in rats. However, in C57BL/6J mice, landmark rotation failed to demonstrate dominant control of the HD signal in 36% of the sessions. In darkness, directional firing became unstable during 42% of the sessions, but landmark control was not associated with HD signal stability in darkness. HD cells were identified in tilted mice, but directional firing properties were not as robust as those of C57BL/6J mice. Most HD cells in tilted mice were controlled by landmark rotation but showed substantial signal degradation across trials. These results support current models that suggest otolithic information is involved in the perception of directional heading. Furthermore, compared with rats, the HD signal in mice appears to be less reliably anchored to prominent environmental cues. PMID:19176815

  14. Canonical Wnt Signaling Activity in Early Stages of Chick Lung Development

    PubMed Central

    daMota, Paulo; Correia-Pinto, Jorge

    2014-01-01

    Wnt signaling pathway is an essential player during vertebrate embryonic development which has been associated with several developmental processes such as gastrulation, body axis formation and morphogenesis of numerous organs, namely the lung. Wnt proteins act through specific transmembrane receptors, which activate intracellular pathways that regulate cellular processes such as cell proliferation, differentiation and death. Morphogenesis of the fetal lung depends on epithelial-mesenchymal interactions that are governed by several growth and transcription factors that regulate cell proliferation, fate, migration and differentiation. This process is controlled by different signaling pathways such as FGF, Shh and Wnt among others. Wnt signaling is recognized as a key molecular player in mammalian pulmonary development but little is known about its function in avian lung development. The present work characterizes, for the first time, the expression pattern of several Wnt signaling members, such as wnt-1, wnt-2b, wnt-3a, wnt-5a, wnt-7b, wnt-8b, wnt-9a, lrp5, lrp6, sfrp1, dkk1, β-catenin and axin2 at early stages of chick lung development. In general, their expression is similar to their mammalian counterparts. By assessing protein expression levels of active/total β-catenin and phospho-LRP6/LRP6 it is revealed that canonical Wnt signaling is active in this embryonic tissue. In vitro inhibition studies were performed in order to evaluate the function of Wnt signaling pathway in lung branching. Lung explants treated with canonical Wnt signaling inhibitors (FH535 and PK115-584) presented an impairment of secondary branch formation after 48 h of culture along with a decrease in axin2 expression levels. Branching analysis confirmed this inhibition. Wnt-FGF crosstalk assessment revealed that this interaction is preserved in the chick lung. This study demonstrates that Wnt signaling is crucial for precise chick lung branching and further supports the avian lung as a good

  15. 17β-Oestradiol enhances the expansion and activation of myeloid-derived suppressor cells via signal transducer and activator of transcription (STAT)-3 signalling in human pregnancy.

    PubMed

    Pan, T; Zhong, L; Wu, S; Cao, Y; Yang, Q; Cai, Z; Cai, X; Zhao, W; Ma, N; Zhang, W; Zhang, H; Zhou, J

    2016-07-01

    During a successful pregnancy, the maternal immune system plays a critical role in maintaining immunotolerance towards semi-allogeneic fetal antigens. Recent studies have indicated that myeloid-derived suppressor cells (MDSCs) are active players in establishing fetal-maternal tolerance; however, the underlying mechanism remains poorly understood. In this study, we observed a significant expansion of monocytic MDSCs (M-MDSCs) in the peripheral blood of pregnant women, which suppressed T cell responses in a reactive oxygen species-dependent manner and required cell-cell contact. The number of M-MDSCs correlated positively with serum oestrogen and progesterone levels. Administration of 17β-oestradiol, but not progesterone, enhanced both the expansion and suppressive activity of M-MDSCs through signal transducer and activator of transcription (STAT)-3. Pretreatment with STAT-3 inhibitor JSI-124 almost completely abrogated the effects of 17β-oestradiol on MDSCs. Collectively, these results demonstrate that 17β-oestradiol-induced STAT-3 signalling plays an important role in both the expansion and activation of MDSCs during human pregnancy, which may benefit the development of novel therapeutic strategies for prevention of immune-related miscarriage. PMID:26969967

  16. Voltage-gated Na+ Channel Activity Increases Colon Cancer Transcriptional Activity and Invasion Via Persistent MAPK Signaling

    NASA Astrophysics Data System (ADS)

    House, Carrie D.; Wang, Bi-Dar; Ceniccola, Kristin; Williams, Russell; Simaan, May; Olender, Jacqueline; Patel, Vyomesh; Baptista-Hon, Daniel T.; Annunziata, Christina M.; Silvio Gutkind, J.; Hales, Tim G.; Lee, Norman H.

    2015-06-01

    Functional expression of voltage-gated Na+ channels (VGSCs) has been demonstrated in multiple cancer cell types where channel activity induces invasive activity. The signaling mechanisms by which VGSCs promote oncogenesis remain poorly understood. We explored the signal transduction process critical to VGSC-mediated invasion on the basis of reports linking channel activity to gene expression changes in excitable cells. Coincidentally, many genes transcriptionally regulated by the SCN5A isoform in colon cancer have an over-representation of cis-acting sites for transcription factors phosphorylated by ERK1/2 MAPK. We hypothesized that VGSC activity promotes MAPK activation to induce transcriptional changes in invasion-related genes. Using pharmacological inhibitors/activators and siRNA-mediated gene knockdowns, we correlated channel activity with Rap1-dependent persistent MAPK activation in the SW620 human colon cancer cell line. We further demonstrated that VGSC activity induces downstream changes in invasion-related gene expression via a PKA/ERK/c-JUN/ELK-1/ETS-1 transcriptional pathway. This is the first study illustrating a molecular mechanism linking functional activity of VGSCs to transcriptional activation of invasion-related genes.

  17. A novel reporter of notch signalling indicates regulated and random notch activation during vertebrate neurogenesis

    PubMed Central

    2011-01-01

    Background Building the complex vertebrate nervous system involves the regulated production of neurons and glia while maintaining a progenitor cell population. Neurogenesis starts asynchronously in different regions of the embryo and occurs over a long period of time, allowing progenitor cells to be exposed to multiple extrinsic signals that regulate the production of different cell types. Notch-mediated cell-cell signalling is one of the mechanisms that maintain the progenitor pool, however, little is known about how the timing of Notch activation is related to the cell cycle and the distinct modes of cell division that generate neurons. An essential tool with which to investigate the role of Notch signalling on cell by cell basis is the development a faithful reporter of Notch activity. Results Here we present a novel reporter for Notch activity based on the promoter of the well characterised Notch target chick Hes5-1, coupled with multiple elements that confer instability, including a destabilized nuclear Venus fluorescent protein and the 3' untranslated region (UTR) of Hes5-1. We demonstrate that this reporter faithfully recapitulates the endogenous expression of Hes5-1 and that it robustly responds to Notch activation in the chick neural tube. Analysis of the patterns of Notch activity revealed by this reporter indicates that although Notch is most frequently activated prior to mitosis it can be activated at any time within the cell cycle. Notch active progenitors undergoing mitosis generate two daughters that both continue to experience Notch signalling. However, cells lacking Notch activity before and during mitosis generate daughters with dissimilar Notch activity profiles. Conclusions A novel Notch reporter with multiple destabilisation elements provides a faithful read-out of endogenous Notch activity on a cell-by-cell basis, as neural progenitors progress through the cell cycle in the chick neural tube. Notch activity patterns in this cell population

  18. Exploring the Tensions between State Activism and School Autonomy.

    ERIC Educational Resources Information Center

    Malen, Betty; Muncey, Donna

    Since the 1970s, states have substantially and dramatically increased their involvement in education while simultaneously endorsing notions of local control. This paper focuses on the impact of such persistent and pervasive state activism on school autonomy. It describes how the proliferation and accumulation of education policies enacted at the…

  19. Monitoring Affect States during Effortful Problem Solving Activities

    ERIC Educational Resources Information Center

    D'Mello, Sidney K.; Lehman, Blair; Person, Natalie

    2010-01-01

    We explored the affective states that students experienced during effortful problem solving activities. We conducted a study where 41 students solved difficult analytical reasoning problems from the Law School Admission Test. Students viewed videos of their faces and screen captures and judged their emotions from a set of 14 states (basic…

  20. Education Finance Legislative Activity and Trends at the State Level.

    ERIC Educational Resources Information Center

    Crampton, Faith E.

    1999-01-01

    Reviews 1997 school finance legislation, comparing legislative activity levels from 1994 to 1997. In 1997, 32 states passed legislation pertaining to capital-outlay funding, tax bases, and taxation for education funding. Half passed legislation for state aid, technology, special-purpose education, budgeting/fiscal management, and school personnel…

  1. 34 CFR 300.704 - State-level activities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false State-level activities. 300.704 Section 300.704 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION ASSISTANCE TO STATES FOR THE EDUCATION OF CHILDREN WITH DISABILITIES Authorization,...

  2. 34 CFR 300.814 - Other State-level activities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Other State-level activities. 300.814 Section 300.814 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION ASSISTANCE TO STATES FOR THE EDUCATION...

  3. 34 CFR 300.812 - Reservation for State activities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 2 2010-07-01 2010-07-01 false Reservation for State activities. 300.812 Section 300.812 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF SPECIAL EDUCATION AND REHABILITATIVE SERVICES, DEPARTMENT OF EDUCATION ASSISTANCE TO STATES FOR THE EDUCATION...

  4. State Activism in School Funding: Goals and Approaches.

    ERIC Educational Resources Information Center

    Theobald, Neil D.

    2000-01-01

    State activism in school funding extends far beyond increasing states' percentage of public-school revenues. However, local districts' share of funding has fallen dramatically over the last 7 decades. Equity-, efficiency-, and liberty-enhancing goals are explained, along with assistance-oriented, persuasive, and regulatory policy approaches.…

  5. Aurora A drives early signalling and vesicle dynamics during T-cell activation

    PubMed Central

    Blas-Rus, Noelia; Bustos-Morán, Eugenio; Pérez de Castro, Ignacio; de Cárcer, Guillermo; Borroto, Aldo; Camafeita, Emilio; Jorge, Inmaculada; Vázquez, Jesús; Alarcón, Balbino; Malumbres, Marcos; Martín-Cófreces, Noa B.; Sánchez-Madrid, Francisco

    2016-01-01

    Aurora A is a serine/threonine kinase that contributes to the progression of mitosis by inducing microtubule nucleation. Here we have identified an unexpected role for Aurora A kinase in antigen-driven T-cell activation. We find that Aurora A is phosphorylated at the immunological synapse (IS) during TCR-driven cell contact. Inhibition of Aurora A with pharmacological agents or genetic deletion in human or mouse T cells severely disrupts the dynamics of microtubules and CD3ζ-bearing vesicles at the IS. The absence of Aurora A activity also impairs the activation of early signalling molecules downstream of the TCR and the expression of IL-2, CD25 and CD69. Aurora A inhibition causes delocalized clustering of Lck at the IS and decreases phosphorylation levels of tyrosine kinase Lck, thus indicating Aurora A is required for maintaining Lck active. These findings implicate Aurora A in the propagation of the TCR activation signal. PMID:27091106

  6. Aurora A drives early signalling and vesicle dynamics during T-cell activation.

    PubMed

    Blas-Rus, Noelia; Bustos-Morán, Eugenio; Pérez de Castro, Ignacio; de Cárcer, Guillermo; Borroto, Aldo; Camafeita, Emilio; Jorge, Inmaculada; Vázquez, Jesús; Alarcón, Balbino; Malumbres, Marcos; Martín-Cófreces, Noa B; Sánchez-Madrid, Francisco

    2016-01-01

    Aurora A is a serine/threonine kinase that contributes to the progression of mitosis by inducing microtubule nucleation. Here we have identified an unexpected role for Aurora A kinase in antigen-driven T-cell activation. We find that Aurora A is phosphorylated at the immunological synapse (IS) during TCR-driven cell contact. Inhibition of Aurora A with pharmacological agents or genetic deletion in human or mouse T cells severely disrupts the dynamics of microtubules and CD3ζ-bearing vesicles at the IS. The absence of Aurora A activity also impairs the activation of early signalling molecules downstream of the TCR and the expression of IL-2, CD25 and CD69. Aurora A inhibition causes delocalized clustering of Lck at the IS and decreases phosphorylation levels of tyrosine kinase Lck, thus indicating Aurora A is required for maintaining Lck active. These findings implicate Aurora A in the propagation of the TCR activation signal. PMID:27091106

  7. Are Auditory Hallucinations Related to the Brain's Resting State Activity? A 'Neurophenomenal Resting State Hypothesis'

    PubMed Central

    2014-01-01

    While several hypotheses about the neural mechanisms underlying auditory verbal hallucinations (AVH) have been suggested, the exact role of the recently highlighted intrinsic resting state activity of the brain remains unclear. Based on recent findings, we therefore developed what we call the 'resting state hypotheses' of AVH. Our hypothesis suggest that AVH may be traced back to abnormally elevated resting state activity in auditory cortex itself, abnormal modulation of the auditory cortex by anterior cortical midline regions as part of the default-mode network, and neural confusion between auditory cortical resting state changes and stimulus-induced activity. We discuss evidence in favour of our 'resting state hypothesis' and show its correspondence with phenomenal, i.e., subjective-experiential features as explored in phenomenological accounts. Therefore I speak of a 'neurophenomenal resting state hypothesis' of auditory hallucinations in schizophrenia. PMID:25598821

  8. Activation of aryl hydrocarbon receptor signaling by extracts of teak and other wood dusts.

    PubMed

    Wilson, Mark J; Sabbioni, Gabriele; Rando, Roy; Miller, Charles A

    2015-12-01

    Wood dusts, as a group, are categorized as known human carcinogens, but the risks of exposure to specific types of wood dusts and the carcinogenic chemicals they contain are not well studied. Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is linked to the carcinogenic action of specific classes of chemicals. Here we examined whether chemicals in various wood dusts had the potential to activate AhR signaling as a potential toxic mechanism of action. We found that methanol extracts of teak, walnut, mahogany, and poplar dusts contained a wide range of AhR ligand activity, whereas extracts of oak, pine, and other softwoods did not contain appreciable activity. Teak dust extract, being particularly potent, was subjected to chemical analysis. The 2-methylanthraquinone (2-MAQ) accounted for the AhR ligand activity and was present at an average concentration of 0.27 parts per hundred in teak dust. Pure 2-MAQ potently induced AhR signaling (EC50 115 nM), confirming that this was the active ligand. Aqueous extracts of teak dust made using yeast or mammalian cell culture medium also contained robust AhR activity, suggesting the 2-MAQ ligand is soluble at bioactive concentrations in physiologically relevant fluids. The high concentration and potency of 2-MAQ in teak wood suggest it may mediate toxic effects through activation of AhR signaling in exposed wood workers. PMID:24898320

  9. Clicks, whistles and pulses: Passive and active signal use in dolphin communication

    NASA Astrophysics Data System (ADS)

    Herzing, Denise L.

    2014-12-01

    The search for signals out of noise is a problem not only with radio signals from the sky but in the study of animal communication. Dolphins use multiple modalities to communicate including body postures, touch, vision, and most elaborately sound. Like SETI radio signal searches, dolphin sound analysis includes the detection, recognition, analysis, and interpretation of signals. Dolphins use both passive listening and active production to communicate. Dolphins use three main types of acoustic signals: frequency modulated whistles (narrowband with harmonics), echolocation (broadband clicks) and burst pulsed sounds (packets of closely spaced broadband clicks). Dolphin sound analysis has focused on frequency-modulated whistles, yet the most commonly used signals are burst-pulsed sounds which, due to their graded and overlapping nature and bimodal inter-click interval (ICI) rates are hard to categorize. We will look at: 1) the mechanism of sound production and categories of sound types, 2) sound analysis techniques and information content, and 3) examples of lessons learned in the study of dolphin acoustics. The goal of this paper is to provide perspective on how animal communication studies might provide insight to both passive and active SETI in the larger context of searching for life signatures.

  10. Boehmenan, a lignan from Hibiscus ficulneus, showed Wnt signal inhibitory activity.

    PubMed

    Shono, Takumi; Ishikawa, Naoki; Toume, Kazufumi; Arai, Midori A; Ahmed, Firoj; Sadhu, Samir K; Ishibashi, Masami

    2015-07-15

    The Wnt signal pathway modulates numerous biological processes, and its aberrant activation is related to various diseases. Therefore, inhibition of the Wnt signal may provide an effective (or efficient) strategy for these diseases. Cell-based luciferase assay targeting the Wnt signal (TOP assay) revealed that Hibiscus ficulneus extract inhibited the Wnt signal. The activity-guided isolation of the MeOH extract of H. ficulneus stems yielded four known (1-4) lignans along with myriceric acid (5). Compounds 1-4 potently inhibited the Wnt signal with TOPflash IC50 values of 1.0, 4.5, 6.3, and 1.9 μM, respectively. Compound 1 exhibited cytotoxicity against both Wnt-dependent (HCT116) and Wnt-independent (RKO) cells. Western blot analysis showed that 1 decreased the expression of full, cytosolic and nuclear β-catenin along with c-myc in STF/293 cells. Our results suggested that 1 may have inhibited the Wnt signal by decreasing β-catenin levels. PMID:26026364

  11. Hedgehog signaling activation induces stem cell proliferation and hormone release in the adult pituitary gland

    PubMed Central

    Pyczek, Joanna; Buslei, Rolf; Schult, David; Hölsken, Annett; Buchfelder, Michael; Heß, Ina; Hahn, Heidi; Uhmann, Anja

    2016-01-01

    Hedgehog (HH) signaling is known to be essential during the embryonal development of the pituitary gland but the knowledge about its role in the adult pituitary and in associated tumors is sparse. In this report we investigated the effect of excess Hh signaling activation in murine pituitary explants and analyzed the HH signaling status of human adenopituitary lobes and a large cohort of pituitary adenomas. Our data show that excess Hh signaling led to increased proliferation of Sox2+ and Sox9+ adult pituitary stem cells and to elevated expression levels of adrenocorticotropic hormone (Acth), growth hormone (Gh) and prolactin (Prl) in the adult gland. Inhibition of the pathway by cyclopamine reversed these effects indicating that active Hh signaling positively regulates proliferative processes of adult pituitary stem cells and hormone production in the anterior pituitary. Since hormone producing cells of the adenohypophysis as well as ACTH-, GH- and PRL-immunopositive adenomas express SHH and its target GLI1, we furthermore propose that excess HH signaling is involved in the development/maintenance of hormone-producing pituitary adenomas. These findings advance the understanding of physiological hormone regulation and may open new treatment options for pituitary tumors. PMID:27109116

  12. Hedgehog signaling activation induces stem cell proliferation and hormone release in the adult pituitary gland.

    PubMed

    Pyczek, Joanna; Buslei, Rolf; Schult, David; Hölsken, Annett; Buchfelder, Michael; Heß, Ina; Hahn, Heidi; Uhmann, Anja

    2016-01-01

    Hedgehog (HH) signaling is known to be essential during the embryonal development of the pituitary gland but the knowledge about its role in the adult pituitary and in associated tumors is sparse. In this report we investigated the effect of excess Hh signaling activation in murine pituitary explants and analyzed the HH signaling status of human adenopituitary lobes and a large cohort of pituitary adenomas. Our data show that excess Hh signaling led to increased proliferation of Sox2(+) and Sox9(+) adult pituitary stem cells and to elevated expression levels of adrenocorticotropic hormone (Acth), growth hormone (Gh) and prolactin (Prl) in the adult gland. Inhibition of the pathway by cyclopamine reversed these effects indicating that active Hh signaling positively regulates proliferative processes of adult pituitary stem cells and hormone production in the anterior pituitary. Since hormone producing cells of the adenohypophysis as well as ACTH-, GH- and PRL-immunopositive adenomas express SHH and its target GLI1, we furthermore propose that excess HH signaling is involved in the development/maintenance of hormone-producing pituitary adenomas. These findings advance the understanding of physiological hormone regulation and may open new treatment options for pituitary tumors. PMID:27109116

  13. TRIM5 Retroviral Restriction Activity Correlates with the Ability To Induce Innate Immune Signaling

    PubMed Central

    Lascano, Josefina; Uchil, Pradeep D.; Mothes, Walther

    2015-01-01

    ABSTRACT Host restriction factor TRIM5 inhibits retroviral transduction in a species-specific manner by binding to and destabilizing the retroviral capsid lattice before reverse transcription is completed. However, the restriction mechanism may not be that simple since TRIM5 E3 ubiquitin ligase activity, the proteasome, autophagy, and TAK1-dependent AP-1 signaling have been suggested to contribute to restriction. Here, we show that, among a panel of seven primate and Carnivora TRIM5 orthologues, each of which has potential for potent retroviral restriction activity, all activated AP-1 signaling. In contrast, TRIM family paralogues most closely related to TRIM5 did not. While each primate species has a single TRIM5 gene, mice have at least seven TRIM5 homologues that cluster into two groups, Trim12a, -b, and -c and Trim30a, -b, -c, and -d. The three Trim12 proteins activated innate immune signaling, while the Trim30 proteins did not, though none of the murine Trim5 homologues restricted any of a panel of cloned retroviruses. To determine if any mouse TRIM5 homologues had potential for restriction activity, each was fused to the human immunodeficiency virus type 1 (HIV-1) CA binding protein cyclophilin A (CypA). The three Trim12-CypA fusions all activated AP-1 and restricted HIV-1 transduction, whereas the Trim30-CypA fusions did neither. AP-1 activation and HIV-1 restriction by the Trim12-CypA fusions were inhibited by disruption of TAK1. Overall then, these experiments demonstrate that there is a strong correlation between TRIM5 retroviral restriction activity and the ability to activate TAK1-dependent innate immune signaling. IMPORTANCE The importance of retroviruses for the evolution of susceptible host organisms cannot be overestimated. Eight percent of the human genome is retrovirus sequence, fixed in the germ line during past infection. Understanding how metazoa protect their genomes from mutagenic retrovirus infection is therefore of fundamental importance to

  14. 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

  15. ASPP1 and ASPP2 bind active RAS, potentiate RAS signalling and enhance p53 activity in cancer cells

    PubMed Central

    Wang, Y; Godin-Heymann, N; Dan Wang, X; Bergamaschi, D; Llanos, S; Lu, X

    2013-01-01

    RAS mutations occur frequently in human cancer and activated RAS signalling contributes to tumour development and progression. Apart from its oncogenic effects on cell growth, active RAS has tumour-suppressive functions via its ability to induce cellular senescence and apoptosis. RAS is known to induce p53-dependent cell cycle arrest, yet its effect on p53-dependent apoptosis remains unclear. We report here that apoptosis-stimulating protein of p53 (ASPP) 1 and 2, two activators of p53, preferentially bind active RAS via their N-terminal RAS-association domains (RAD). Additionally, ASPP2 colocalises with and contributes to RAS cellular membrane localisation and potentiates RAS signalling. In cancer cells, ASPP1 and ASPP2 cooperate with oncogenic RAS to enhance the transcription and apoptotic function of p53. Thus, loss of ASPP1 and ASPP2 in human cancer cells may contribute to the full transforming property of RAS oncogene. PMID:23392125

  16. False alarm reduction in BSN-based cardiac monitoring using signal quality and activity type information.

    PubMed

    Tanantong, Tanatorn; Nantajeewarawat, Ekawit; Thiemjarus, Surapa

    2015-01-01

    False alarms in cardiac monitoring affect the quality of medical care, impacting on both patients and healthcare providers. In continuous cardiac monitoring using wireless Body Sensor Networks (BSNs), the quality of ECG signals can be deteriorated owing to several factors, e.g., noises, low battery power, and network transmission problems, often resulting in high false alarm rates. In addition, body movements occurring from activities of daily living (ADLs) can also create false alarms. This paper presents a two-phase framework for false arrhythmia alarm reduction in continuous cardiac monitoring, using signals from an ECG sensor and a 3D accelerometer. In the first phase, classification models constructed using machine learning algorithms are used for labeling input signals. ECG signals are labeled with heartbeat types and signal quality levels, while 3D acceleration signals are labeled with ADL types. In the second phase, a rule-based expert system is used for combining classification results in order to determine whether arrhythmia alarms should be accepted or suppressed. The proposed framework was validated on datasets acquired using BSNs and the MIT-BIH arrhythmia database. For the BSN dataset, acceleration and ECG signals were collected from 10 young and 10 elderly subjects while they were performing ADLs. The framework reduced the false alarm rate from 9.58% to 1.43% in our experimental study, showing that it can potentially assist physicians in diagnosing a vast amount of data acquired from wireless sensors and enhance the performance of continuous cardiac monitoring. PMID:25671512

  17. False Alarm Reduction in BSN-Based Cardiac Monitoring Using Signal Quality and Activity Type Information

    PubMed Central

    Tanantong, Tanatorn; Nantajeewarawat, Ekawit; Thiemjarus, Surapa

    2015-01-01

    False alarms in cardiac monitoring affect the quality of medical care, impacting on both patients and healthcare providers. In continuous cardiac monitoring using wireless Body Sensor Networks (BSNs), the quality of ECG signals can be deteriorated owing to several factors, e.g., noises, low battery power, and network transmission problems, often resulting in high false alarm rates. In addition, body movements occurring from activities of daily living (ADLs) can also create false alarms. This paper presents a two-phase framework for false arrhythmia alarm reduction in continuous cardiac monitoring, using signals from an ECG sensor and a 3D accelerometer. In the first phase, classification models constructed using machine learning algorithms are used for labeling input signals. ECG signals are labeled with heartbeat types and signal quality levels, while 3D acceleration signals are labeled with ADL types. In the second phase, a rule-based expert system is used for combining classification results in order to determine whether arrhythmia alarms should be accepted or suppressed. The proposed framework was validated on datasets acquired using BSNs and the MIT-BIH arrhythmia database. For the BSN dataset, acceleration and ECG signals were collected from 10 young and 10 elderly subjects while they were performing ADLs. The framework reduced the false alarm rate from 9.58% to 1.43% in our experimental study, showing that it can potentially assist physicians in diagnosing a vast amount of data acquired from wireless sensors and enhance the performance of continuous cardiac monitoring. PMID:25671512

  18. Mitogen Activated Protein Kinase Family Proteins and c-jun Signaling in Injury-induced Schwann Cell Plasticity.

    PubMed

    Lee, Hye Jeong; Shin, Yoon Kyung; Park, Hwan Tae

    2014-06-01

    Schwann cells (SCs) in the peripheral nerves myelinate axons during postnatal development to allow saltatory conduction of nerve impulses. Well-organized structures of myelin sheathes are maintained throughout life unless nerves are insulted. After peripheral nerve injury, unidentified signals from injured nerves drive SC dedifferentiation into an immature state. Dedifferentiated SCs participate in axonal regeneration by producing neurotrophic factors and removing degenerating nerve debris. In this review, we focus on the role of mitogen activated protein kinase family proteins (MAP kinases) in SC dedifferentiation. In addition, we will highlight neuregulin 1 and the transcription factor c-jun as upstream and downstream signals for MAP kinases in SC responses to nerve injury. PMID:24963277

  19. A receptor state space model of the insulin signalling system in glucose transport.

    PubMed

    Gray, Catheryn W; Coster, Adelle C F

    2015-12-01

    Insulin is a potent peptide hormone that regulates glucose levels in the blood. Insulin-sensitive cells respond to insulin stimulation with the translocation of glucose transporter 4 (GLUT4) to the plasma membrane (PM), enabling the clearance of glucose from the blood. Defects in this process can give rise to insulin resistance and ultimately diabetes. One widely cited model of insulin signalling leading to glucose transport is that of Sedaghat et al. (2002) Am. J. Physiol. Endocrinol. Metab. 283, E1084-E1101. Consisting of 20 deterministic ordinary differential equations (ODEs), it is the most comprehensive model of insulin signalling to date. However, the model possesses some major limitations, including the non-conservation of key components. In the current work, we detail mathematical and sensitivity analyses of the Sedaghat model. Based on the results of these analyses, we propose a reduced state space model of the insulin receptor subsystem. This reduced model maintains the input-output relation of the original model but is computationally more efficient, analytically tractable and resolves some of the limitations of the Sedaghat model. PMID:25673317

  20. Effects of anesthesia on BOLD signal and neuronal activity in the somatosensory cortex.

    PubMed

    Aksenov, Daniil P; Li, Limin; Miller, Michael J; Iordanescu, Gheorghe; Wyrwicz, Alice M

    2015-11-01

    Most functional magnetic resonance imaging (fMRI) animal studies rely on anesthesia, which can induce a variety of drug-dependent physiological changes, including depression of neuronal activity and cerebral metabolism as well as direct effects on the vasculature. The goal of this study was to characterize the effects of anesthesia on the BOLD signal and neuronal activity. Simultaneous fMRI and electrophysiology were used to measure changes in single units (SU), multi-unit activity (MUA), local field potentials (LFP), and the blood oxygenation level-dependent (BOLD) response in the somatosensory cortex during whisker stimulation of rabbits before, during and after anesthesia with fentanyl or isoflurane. Our results indicate that anesthesia modulates the BOLD signal as well as both baseline and stimulus-evoked neuronal activity, and, most significantly, that the relationship between the BOLD and electrophysiological signals depends on the type of anesthetic. Specifically, the behavior of LFP observed under isoflurane did not parallel the behavior of BOLD, SU, or MUA. These findings suggest that the relationship between these signals may not be straightforward. BOLD may scale more closely with the best measure of the excitatory subcomponents of the underlying neuronal activity, which may vary according to experimental conditions that alter the excitatory/inhibitory balance in the cortex. PMID:26104288

  1. 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

  2. Calmodulin activity regulates group I metabotropic glutamate receptor-mediated signal transduction and synaptic depression.

    PubMed

    Sethna, Ferzin; Zhang, Ming; Kaphzan, Hanoch; Klann, Eric; Autio, Dawn; Cox, Charles L; Wang, Hongbing

    2016-05-01

    Group I metabotropic glutamate receptors (mGluR), including mGluR1 and mGluR 5 (mGluR1/5), are coupled to Gq and modulate activity-dependent synaptic plasticity. Direct activation of mGluR1/5 causes protein translation-dependent long-term depression (LTD). Although it has been established that intracellular Ca(2+) and the Gq-regulated signaling molecules are required for mGluR1/5 LTD, whether and how Ca(2+) regulates Gq signaling and upregulation of protein expression remain unknown. Through pharmacological inhibition, we tested the function of the Ca(2+) sensor calmodulin (CaM) in intracellular signaling triggered by the activation of mGluR1/5. CaM inhibitor N-[4-aminobutyl]-5-chloro-2-naphthalenesulfonamide hydrochloride (W13) suppressed the mGluR1/5-stimulated activation of extracellular signal-regulated kinase 1/2 (ERK1/2) and p70-S6 kinase 1 (S6K1) in hippocampal neurons. W13 also blocked the mGluR1/5 agonist-induced synaptic depression in hippocampal slices and in anesthetized mice. Consistent with the function of CaM, inhibiting the downstream targets Ca(2+) /CaM-dependent protein kinases (CaMK) blocked ERK1/2 and S6K1 activation. Furthermore, disruption of the CaM-CaMK-ERK1/2 signaling cascade suppressed the mGluR1/5-stimulated upregulation of Arc expression. Altogether, our data suggest CaM as a new Gq signaling component for coupling Ca(2+) and protein upregulation and regulating mGluR1/5-mediated synaptic modification. PMID:26864654

  3. Surfactant protein A integrates activation signal strength to differentially modulate T cell proliferation.

    PubMed

    Mukherjee, Sambuddho; Giamberardino, Charles; Thomas, Joseph; Evans, Kathy; Goto, Hisatsugu; Ledford, Julie G; Hsia, Bethany; Pastva, Amy M; Wright, Jo Rae

    2012-02-01

    Pulmonary surfactant lipoproteins lower the surface tension at the alveolar-airway interface of the lung and participate in host defense. Previous studies reported that surfactant protein A (SP-A) inhibits lymphocyte proliferation. We hypothesized that SP-A-mediated modulation of T cell activation depends upon the strength, duration, and type of lymphocyte activating signals. Modulation of T cell signal strength imparted by different activating agents ex vivo and in vivo in different mouse models and in vitro with human T cells shows a strong correlation between strength of signal (SoS) and functional effects of SP-A interactions. T cell proliferation is enhanced in the presence of SP-A at low SoS imparted by exogenous mitogens, specific Abs, APCs, or in homeostatic proliferation. Proliferation is inhibited at higher SoS imparted by different doses of the same T cell mitogens or indirect stimuli such as LPS. Importantly, reconstitution with exogenous SP-A into the lungs of SP-A(-/-) mice stimulated with a strong signal also resulted in suppression of T cell proliferation while elevating baseline proliferation in unstimulated T cells. These signal strength and SP-A-dependent effects are mediated by changes in intracellular Ca(2+) levels over time, involving extrinsic Ca(2+)-activated channels late during activation. These effects are intrinsic to the global T cell population and are manifested in vivo in naive as well as memory phenotype T cells. Thus, SP-A appears to integrate signal thresholds to control T cell proliferation. PMID:22219327

  4. Two Drosophila suppressors of cytokine signaling (SOCS) differentially regulate JAK and EGFR pathway activities

    PubMed Central

    Rawlings, Jason S; Rennebeck, Gabriela; Harrison, Susan MW; Xi, Rongwen; Harrison, Douglas A

    2004-01-01

    Background The Janus kinase (JAK) cascade is an essential and well-conserved pathway required to transduce signals for a variety of ligands in both vertebrates and invertebrates. While activation of the pathway is essential to many processes, mutations from mammals and Drosophila demonstrate that regulation is also critical. The SOCS (Suppressor Of Cytokine Signaling) proteins in mammals are regulators of the JAK pathway that participate in a negative feedback loop, as they are transcriptionally activated by JAK signaling. Examination of one Drosophila SOCS homologue, Socs36E, demonstrated that its expression is responsive to JAK pathway activity and it is capable of downregulating JAK signaling, similar to the well characterized mammalian SOCS. Results Based on sequence analysis of the Drosophila genome, there are three identifiable SOCS homologues in flies. All three are most similar to mammalian SOCS that have not been extensively characterized: Socs36E is most similar to mammalian SOCS5, while Socs44A and Socs16D are most similar to mammalian SOCS6 and 7. Although Socs44A is capable of repressing JAK activity in some tissues, its expression is not regulated by the pathway. Furthermore, Socs44A can enhance the activity of the EGFR/MAPK signaling cascade, in contrast to Socs36E. Conclusions Two Drosophila SOCS proteins have some overlapping and some distinct capabilities. While Socs36E behaves similarly to the canonical vertebrate SOCS, Socs44A is not part of a JAK pathway negative feedback loop. Nonetheless, both SOCS regulate JAK and EGFR signaling pathways, albeit differently. The non-canonical properties of Socs44A may be representative of the class of less characterized vertebrate SOCS with which it shares greatest similarity. PMID:15488148

  5. Role of Nongenomic Signaling Pathways Activated by Aldosterone During Cardiac Reperfusion Injury.

    PubMed

    Ashton, Anthony W; Le, Thi Y L; Gomez-Sanchez, Celso E; Morel-Kopp, Marie-Christine; McWhinney, Brett; Hudson, Amanda; Mihailidou, Anastasia S

    2015-08-01

    Aldosterone (Aldo) activates both genomic and nongenomic signaling pathways in the cardiovascular system. Activation of genomic signaling pathways contributes to the adverse cardiac actions of Aldo during reperfusion injury; however, the extent nongenomic signaling pathways contribute has been difficult to identify due to lack of a specific ligand that activates only nongenomic signaling pathways. Using a pegylated aldosterone analog, aldosterone-3-carboxymethoxylamine-TFP ester conjugated to methoxypegylated amine (Aldo-PEG), we are able for the first time to distinguish between nongenomic and genomic cardiac actions of Aldo. We confirm Aldo-PEG activates phosphorylation of ERK1/2 in rat cardiomyocyte H9c2 cells similar to Aldo and G protein-coupled receptor 30 (GPR30 or GPER) agonist G1. GPER antagonist, G36, but not mineralocorticoid receptor (MR) antagonist spironolactone, prevented ERK1/2 phosphorylation by Aldo, Aldo-PEG, and G1. The selective nongenomic actions of Aldo-PEG are confirmed, with Aldo-PEG increasing superoxide production in H9c2 cells to similar levels as Aldo but having no effect on subcellular localization of MR. Striatin serves as a scaffold for GPER and MR, with GPER antagonist G36, but not spironolactone, restoring MR-striatin complexes. Aldo-PEG had no effect on MR-dependent transcriptional activation, whereas Aldo increased transcript levels of serum-regulated kinase 1 and plasminogen activator inhibitor-1. Using our ex vivo experimental rat model of myocardial infarction, we found aggravated infarct size and apoptosis by Aldo but not Aldo-PEG. Our studies confirm that in the heart, activation of nongenomic signaling pathways alone are not sufficient to trigger the deleterious effects of aldosterone during myocardial reperfusion injury. PMID:26121234

  6. Swelling-Activated Ca2+ Channels Trigger Ca2+ Signals in Merkel Cells

    PubMed Central

    Haeberle, Henry; Bryan, Leigh A.; Vadakkan, Tegy J.; Dickinson, Mary E.; Lumpkin, Ellen A.

    2008-01-01

    Merkel cell-neurite complexes are highly sensitive touch receptors comprising epidermal Merkel cells and sensory afferents. Based on morphological and molecular studies, Merkel cells are proposed to be mechanosensory cells that signal afferents via neurotransmission; however, functional studies testing this hypothesis in intact skin have produced conflicting results. To test this model in a simplified system, we asked whether purified Merkel cells are directly activated by mechanical stimulation. Cell shape was manipulated with anisotonic solution changes and responses were monitored by Ca2+ imaging with fura-2. We found that hypotonic-induced cell swelling, but not hypertonic solutions, triggered cytoplasmic Ca2+ transients. Several lines of evidence indicate that these signals arise from swelling-activated Ca2+-permeable ion channels. First, transients were reversibly abolished by chelating extracellular Ca2+, demonstrating a requirement for Ca2+ influx across the plasma membrane. Second, Ca2+ transients were initially observed near the plasma membrane in cytoplasmic processes. Third, voltage-activated Ca2+ channel (VACC) antagonists reduced transients by half, suggesting that swelling-activated channels depolarize plasma membranes to activate VACCs. Finally, emptying internal Ca2+ stores attenuated transients by 80%, suggesting Ca2+ release from stores augments swelling-activated Ca2+ signals. To identify candidate mechanotransduction channels, we used RT-PCR to amplify ion-channel transcripts whose pharmacological profiles matched those of hypotonic-evoked Ca2+ signals in Merkel cells. We found 11 amplicons, including PKD1, PKD2, and TRPC1, channels previously implicated in mechanotransduction in other cells. Collectively, these results directly demonstrate that Merkel cells are activated by hypotonic-evoked swelling, identify cellular signaling mechanisms that mediate these responses, and support the hypothesis that Merkel cells contribute to touch reception

  7. Low-cost detection of RC-IED activation signals in VHF band

    NASA Astrophysics Data System (ADS)

    Camargo Suarez, Victor Hugo; Marulanda B., Jose Ignacio

    2014-05-01

    The proliferation of Radio Controlled Improvised Explosive Devices (RC-IED) is a growing threat around the world. The ease of construction and low cost of these devices are transforming common things in lethal tramps. The fight against this threats normally involves the use of sophisticated and expensive equipment of Electronic Warfare based on high speed DSP systems, just to detect the presence of detonation signals. In this work is showed how to find activation signals based on the characteristic of the power in a specific band and the previous knowledge about the detonation signals. As proof of concept we have taken the information about the RC-IEDs used in the Colombian conflict and develop an algorithm to find detonation signals based on the measured power in frequencies between 136 MHz and 174 MHz (2 meter civil band)

  8. Opposing activities of Notch and Wnt signaling regulate intestinal stem cells and gut homeostasis.

    PubMed

    Tian, Hua; Biehs, Brian; Chiu, Cecilia; Siebel, Christian W; Wu, Yan; Costa, Mike; de Sauvage, Frederic J; Klein, Ophir D

    2015-04-01

    Proper organ homeostasis requires tight control of adult stem cells and differentiation through the integration of multiple inputs. In the mouse small intestine, Notch and Wnt signaling are required both for stem cell maintenance and for a proper balance of differentiation between secretory and absorptive cell lineages. In the absence of Notch signaling, stem cells preferentially generate secretory cells at the expense of absorptive cells. Here, we use function-blocking antibodies against Notch receptors to demonstrate that Notch blockade perturbs intestinal stem cell function by causing a derepression of the Wnt signaling pathway, leading to misexpression of prosecretory genes. Importantly, attenuation of the Wnt pathway rescued the phenotype associated with Notch blockade. These studies bring to light a negative regulatory mechanism that maintains stem cell activity and balanced differentiation, and we propose that the interaction between Wnt and Notch signaling described here represents a common theme in adult stem cell biology. PMID:25818302

  9. Signaling gradients in cascades of two-state reaction-diffusion systems.

    PubMed

    Berezhkovskii, Alexander M; Coppey, Mathieu; Shvartsman, Stanislav Y

    2009-01-27

    Biological networks frequently use cascades, generally defined as chain-like arrangements of similar modules. Spatially lumped cascades can serve as noise filters, time-delay, or thresholding elements. The operation and functional capabilities of spatially distributed cascades are much less understood. Motivated by studies of pattern formation in the early Drosophila embryo, we analyze cascades of 2-state reaction-diffusion systems. At each stage within such as a cascade, a diffusible particle is reversibly bound by immobile traps and can be annihilated in both mobile and immobile states. When trapped, these particles drive the next stage by converting mobile particles of a different type from a passive to active form. The cascade initiated by injection of mobile particles into the first stage. We derive analytical expressions for the steady-state concentration profiles of mobile and immobile particles and analyze how the output of a cascade is controlled by properties of the constituent stages. PMID:19147842

  10. Palmitoylation controls DLK localization, interactions and activity to ensure effective axonal injury signaling

    PubMed Central

    Holland, Sabrina M.; Collura, Kaitlin M.; Ketschek, Andrea; Noma, Kentaro; Ferguson, Toby A.; Jin, Yishi; Gallo, Gianluca; Thomas, Gareth M.

    2016-01-01

    Dual leucine-zipper kinase (DLK) is critical for axon-to-soma retrograde signaling following nerve injury. However, it is unknown how DLK, a predicted soluble kinase, conveys long-distance signals and why homologous kinases cannot compensate for loss of DLK. Here, we report that DLK, but not homologous kinases, is palmitoylated at a conserved site adjacent to its kinase domain. Using short-hairpin RNA knockdown/rescue, we find that palmitoylation is critical for DLK-dependent retrograde signaling in sensory axons. This functional importance is because of three novel cellular and molecular roles of palmitoylation, which targets DLK to trafficking vesicles, is required to assemble DLK signaling complexes and, unexpectedly, is essential for DLK’s kinase activity. By simultaneously controlling DLK localization, interactions, and activity, palmitoylation ensures that only vesicle-bound DLK is active in neurons. These findings explain how DLK specifically mediates nerve injury responses and reveal a novel cellular mechanism that ensures the specificity of neuronal kinase signaling. PMID:26719418

  11. The Viral Oncoprotein LMP1 Exploits TRADD for Signaling by Masking Its Apoptotic Activity

    PubMed Central

    Schneider, Frank; Neugebauer, Julia; Griese, Janine; Liefold, Nicola; Kutz, Helmut; Briseño, Cinthia; Kieser, Arnd

    2008-01-01

    The tumor necrosis factor (TNF)-receptor 1–associated death domain protein (TRADD) mediates induction of apoptosis as well as activation of NF-κB by cellular TNF-receptor 1 (TNFR1). TRADD is also recruited by the latent membrane protein 1 (LMP1) oncoprotein of Epstein-Barr virus, but its role in LMP1 signaling has remained enigmatic. In human B lymphocytes, we have generated, to our knowledge, the first genetic knockout of TRADD to investigate TRADD's role in LMP1 signal transduction. Our data from TRADD-deficient cells demonstrate that TRADD is a critical signaling mediator of LMP1 that is required for LMP1 to recruit and activate I-κB kinase β (IKKβ). However, in contrast to TNFR1, LMP1-induced TRADD signaling does not induce apoptosis. Searching for the molecular basis for this observation, we characterized the 16 C-terminal amino acids of LMP1 as an autonomous and unique virus-derived TRADD-binding domain. Replacing the death domain of TNFR1 by LMP1′s TRADD-binding domain converts TNFR1 into a nonapoptotic receptor that activates NF-κB through a TRAF6-dependent pathway, like LMP1 but unlike wild-type TNFR1. Thus, the unique interaction of LMP1 with TRADD encodes the transforming phenotype of viral TRADD signaling and masks TRADD's pro-apoptotic function. PMID:18198944

  12. A Phosphatase Activity of Sts-1 Contributes to the Suppression of TCR Signaling

    SciTech Connect

    Mikhailik,A.; Ford, B.; Keller, J.; Chen, Y.; Nassar, N.; Carpino, N.

    2007-01-01

    Precise signaling by the T cell receptor (TCR) is crucial for a proper immune response. To ensure that T cells respond appropriately to antigenic stimuli, TCR signaling pathways are subject to multiple levels of regulation. Sts-1 negatively regulates signaling pathways downstream of the TCR by an unknown mechanism(s). Here, we demonstrate that Sts-1 is a phosphatase that can target the tyrosine kinase Zap-70 among other proteins. The X-ray structure of the Sts-1 C terminus reveals that it has homology to members of the phosphoglycerate mutase/acid phosphatase (PGM/AcP) family of enzymes, with residues known to be important for PGM/AcP catalytic activity conserved in nature and position in Sts-1. Point mutations that impair Sts-1 phosphatase activity in vitro also impair the ability of Sts-1 to regulate TCR signaling in T cells. These observations reveal a PGM/AcP-like enzyme activity involved in the control of antigen receptor signaling.

  13. Focal Activation of Cells by Plasmon Resonance Assisted Optical Injection of Signaling Molecules

    PubMed Central

    2015-01-01

    Experimental methods for single cell intracellular delivery are essential for probing cell signaling dynamics within complex cellular networks, such as those making up the tumor microenvironment. Here, we show a quantitative and general method of interrogation of signaling pathways. We applied highly focused near-infrared laser light to optically inject gold-coated liposomes encapsulating bioactive molecules into single cells for focal activation of cell signaling. For this demonstration, we encapsulated either inositol trisphosphate (IP3), an endogenous cell signaling second messenger, or adenophostin A (AdA), a potent analogue of IP, within 100 nm gold-coated liposomes, and injected these gold-coated liposomes and their contents into the cytosol of single ovarian carcinoma cells to initiate calcium (Ca2+) release from intracellular stores. Upon optical injection of IP3 or AdA at doses above the activation threshold, we observed increases in cytosolic Ca2+ concentration within the injected cell initiating the propagation of a Ca2+ wave throughout nearby cells. As confirmed by octanol-induced inhibition, the intercellular Ca2+ wave traveled via gap junctions. Optical injection of gold-coated liposomes represents a quantitative method of focal activation of signaling cascades of broad interest in biomedical research. PMID:24877558

  14. Graded boosting of synaptic signals by low-threshold voltage-activated calcium conductance.

    PubMed

    Carbó Tano, Martín; Vilarchao, María Eugenia; Szczupak, Lidia

    2015-07-01

    Low-threshold voltage-activated calcium conductances (LT-VACCs) play a substantial role in shaping the electrophysiological attributes of neurites. We have investigated how these conductances affect synaptic integration in a premotor nonspiking (NS) neuron of the leech nervous system. These cells exhibit an extensive neuritic tree, do not fire Na(+)-dependent spikes, but express an LT-VACC that was sensitive to 250 μM Ni(2+) and 100 μM NNC 55-0396 (NNC). NS neurons responded to excitation of mechanosensory pressure neurons with depolarizing responses for which amplitude was a linear function of the presynaptic firing frequency. NNC decreased these synaptic responses and abolished the concomitant widespread Ca(2+) signals. Coherent with the interpretation that the LT-VACC amplified signals at the postsynaptic level, this conductance also amplified the responses of NS neurons to direct injection of sinusoidal current. Synaptic amplification thus is achieved via a positive feedback in which depolarizing signals activate an LT-VACC that, in turn, boosts these signals. The wide distribution of LT-VACC could support the active propagation of depolarizing signals, turning the complex NS neuritic tree into a relatively compact electrical compartment. PMID:25972583

  15. Glucose deprivation activates a metabolic and signaling amplification loop leading to cell death

    PubMed Central

    Graham, Nicholas A; Tahmasian, Martik; Kohli, Bitika; Komisopoulou, Evangelia; Zhu, Maggie; Vivanco, Igor; Teitell, Michael A; Wu, Hong; Ribas, Antoni; Lo, Roger S; Mellinghoff, Ingo K; Mischel, Paul S; Graeber, Thomas G

    2012-01-01

    The altered metabolism of cancer can render cells dependent on the availability of metabolic substrates for viability. Investigating the signaling mechanisms underlying cell death in cells dependent upon glucose for survival, we demonstrate that glucose withdrawal rapidly induces supra-physiological levels of phospho-tyrosine signaling, even in cells expressing constitutively active tyrosine kinases. Using unbiased mass spectrometry-based phospho-proteomics, we show that glucose withdrawal initiates a unique signature of phospho-tyrosine activation that is associated with focal adhesions. Building upon this observation, we demonstrate that glucose withdrawal activates a positive feedback loop involving generation of reactive oxygen species (ROS) by NADPH oxidase and mitochondria, inhibition of protein tyrosine phosphatases by oxidation, and increased tyrosine kinase signaling. In cells dependent on glucose for survival, glucose withdrawal-induced ROS generation and tyrosine kinase signaling synergize to amplify ROS levels, ultimately resulting in ROS-mediated cell death. Taken together, these findings illustrate the systems-level cross-talk between metabolism and signaling in the maintenance of cancer cell homeostasis. PMID:22735335

  16. Mechanical Stretch-Induced Activation of ROS/RNS Signaling in Striated Muscle

    PubMed Central

    Ward, Christopher W.; Prosser, Benjamin L.

    2014-01-01

    Significance: Mechanical activation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) occurs in striated muscle and affects Ca2+ signaling and contractile function. ROS/RNS signaling is tightly controlled, spatially compartmentalized, and source specific. Recent Advances: Here, we review the evidence that within the contracting myocyte, the trans-membrane protein NADPH oxidase 2 (Nox2) is the primary source of ROS generated during contraction. We also review a newly characterized signaling cascade in cardiac and skeletal muscle in which the microtubule network acts as a mechanotransduction element that activates Nox2-dependent ROS generation during mechanical stretch, a pathway termed X-ROS signaling. Critical Issues: In the heart, X-ROS acts locally and affects the sarcoplasmic reticulum (SR) Ca2+ release channels (ryanodine receptors) and tunes Ca2+ signaling during physiological behavior, but excessive X-ROS can promote Ca2+-dependent arrhythmias in pathology. In skeletal muscle, X-ROS sensitizes Ca2+-permeable sarcolemmal “transient receptor potential” channels, a pathway that is critical for sustaining SR load during repetitive contractions, but when in excess, it is maladaptive in diseases such as Duchenne Musclar dystrophy. Future Directions: New advances in ROS/RNS detection as well as molecular manipulation of signaling pathways will provide critical new mechanistic insights into the details of X-ROS signaling. These efforts will undoubtedly reveal new avenues for therapeutic intervention in the numerous diseases of striated muscle in which altered mechanoactivation of ROS/RNS production has been identified. Antioxid. Redox Signal. 20, 929–936. PMID:23971496

  17. The Very Young and Education: 1974 State Activity.

    ERIC Educational Resources Information Center

    Hayas, Denise Kale; Ross, Doris M.

    This booklet contains more than 100 brief descriptions of early childhood projects, activities, studies, and legislation obtained from newsletters, bulletins, and the Education Commission of the States' (ECS) 1974 Annual Survey. Only legislation and activities that have been validated or newly reported are included. Bills which failed or were…

  18. Light-activated solid-state opening switch

    NASA Astrophysics Data System (ADS)

    Heyse, Mark W.; Petr, Rodney A.; Kachen, George I.; Reilly, James P.; Schaefer, Raymond B.

    1993-01-01

    Light-activated solid-state opening switches are shown to be a viable approach for switching inductive circuits. Measured photoswitch performance indicates that light-activated opening switches have the power density ratings needed to develop compact inductive power systems.

  19. Activation of murine microglial N9 cells is attenuated through cannabinoid receptor CB2 signaling.

    PubMed

    Ma, Lei; Jia, Ji; Liu, Xiangyu; Bai, Fuhai; Wang, Qiang; Xiong, Lize

    2015-02-27

    Inhibition of microglial activation is effective in treating various neurological disorders. Activation of microglial cannabinoid CB2 receptor induces anti-inflammatory effects, and the mechanism, however, is still elusive. Microglia could be activated into the classic activated state (M1 state) or the alternative activated state (M2 state), the former is cytotoxic, and the latter is neurotrophic. In this study, we used lipopolysaccharide (LPS) plus interferon-γ (IFNγ) to activate N9 microglia and hypothesized the pretreatment with cannabinoid CB2 receptor agonist AM1241 attenuates microglial activation by shifting microglial M1 to M2 state. We found that pretreatment with 5 μM AM1241 at 1 h before microglia were exposed to LPS plus IFNγ decreased the expression of inducible nitric oxide synthase (iNOS) and the release of pro-inflammatory factors, increased the expression of arginase 1 (Arg-1) and the release of anti-inflammatory and neurotrophic factors in microglia. However, these effects induced by AM1241 pretreatment were significantly reversed in the presence of 10 μM cannabinoid CB2 receptor antagonist AM630 or 10 μM protein kinase C (PKC) inhibitor chelerythrine. These findings indicated that AM1241 pretreatment attenuates microglial activation by shifting M1 to M2 activated state via CB2 receptor, and the AM1241-induced anti-inflammatory effects may be mediated by PKC. PMID:25637536

  20. Activation of the wnt/β-Catenin Signaling Pathway in Polymyositis, Dermatomyositis and Duchenne Muscular Dystrophy

    PubMed Central

    Liu, Fuchen; Liang, Zonglai; Xu, Jingwen; Li, Wei; Zhao, Dandan; Zhao, Yuying

    2016-01-01

    Background and Purpose The wnt/β-catenin signaling pathway plays a critical role in embryonic development and adult-tissue homeostasis. Recent investigations implicate the importance of wnt/β-catenin signaling in normal wound healing and its sustained activation being associated with fibrogenesis. We investigated the immunolocalization and activation of wnt/β-catenin in polymyositis (PM), dermatomyositis (DM), and Duchenne muscular dystrophy (DMD). Methods Immunofluorescence staining and Western blot analysis of β-catenin were performed in muscle specimens from 6 PM, 8 DM, and 6 DMD subjects. The β-catenin/Tcf4 DNA-binding activity in muscle was studied using an electrophoretic mobility shift assay (EMSA), and serum wnt/β-catenin/Tcf transcriptional activity was measured using a luciferase reporter gene assay. Results Immunoreactivity for β-catenin was found in the cytoplasm and nuclei of muscle fibers in PM, DM, and DMD. The protein level of β-catenin was elevated, and EMSA analysis confirmed the activation of wnt/β-catenin signaling. The transcriptional activities of β-catenin/Tcf in the circulation were increased in patients with PM, DM, and DMD, especially in those with interstitial lung disease, and these transcriptional activities decreased when PM or DM patients exhibited obvious clinical improvements. Conclusions Our findings indicate that wnt/β-catenin signaling is activated in PM, DM, and DMD. Its activation in muscle tissue and the circulation may play a role in modulating muscle regeneration and be at least partly involved in the process of muscle and pulmonary fibrosis. PMID:27165423

  1. Rapid estrogen signaling negatively regulates PTEN activity through phosphorylation in endometrial cancer cells

    PubMed Central

    Scully, Melanie M.; Palacios-Helgeson, Leslie K.; Wah, Lah S.; Jackson, Twila A.

    2014-01-01

    Hyperestrogenicity is a risk factor for endometrial cancer. 17β-estradiol (E2) is known to stimulate both genomic and nongenomic estrogen receptor-α (ERα) actions in a number of reproductive tissues. However, the contributions of transcription-independent ERα signaling on normal and malignant endometrium are not fully understood. Phosphatase and tensin homolog (PTEN) is a tumor suppressor that decreases cellular mitosis primarily through negative regulation of the phosphoinositide 3-kinase/AKT signaling axis. PTEN levels are elevated during the E2 dominated, mitotically active, proliferative phase of the menstrual cycle, indicating possible hormonal regulation of PTEN in the uterus. In order to determine if rapid E2 signaling regulates PTEN, we used ERα positive, PTEN positive, endometrial cells. We show that cytosolic E2/ERα signaling leads to increased phosphorylation of PTEN at key regulatory residues. Importantly, E2 stimulation decreased PTEN lipid phosphatase activity and caused consequent increases in phospho-AKT. We further demonstrate that cytosolic ERα forms a complex with PTEN in an E2-dependent manner, and that ERα constitutively complexes with protein kinase2-α (CK2α), a kinase previously shown to phosphorylate the C-terminal tail of PTEN. These results provide mechanistic support for an E2-dependent, ERα cytosolic signaling complex that negatively regulates PTEN activity through carboxy terminus phosphorylation. Using an animal model, we show that sustained E2 signaling results in increased phospho-PTEN (S380, T382, T383), total PTEN and phospho-AKT (S473). Taken together, we provide a novel mechanism in which transcription-independent E2/ERα signaling may promote a pro-tumorigenic environment in the endometrium. PMID:24844349

  2. Alternative Activation Mechanisms of Protein Kinase B Trigger Distinct Downstream Signaling Responses.

    PubMed

    Balzano, Deborah; Fawal, Mohamad-Ali; Velázquez, Jose V; Santiveri, Clara M; Yang, Joshua; Pastor, Joaquín; Campos-Olivas, Ramón; Djouder, Nabil; Lietha, Daniel

    2015-10-01

    Protein kinase B (PKB/Akt) is an important mediator of signals that control various cellular processes including cell survival, growth, proliferation, and metabolism. PKB promotes these processes by phosphorylating many cellular targets, which trigger distinct downstream signaling events. However, how PKB is able to selectively target its substrates to induce specific cellular functions remains elusive. Here we perform a systematic study to dissect mechanisms that regulate intrinsic kinase activity versus mechanisms that specifically regulate activity toward specific substrates. We demonstrate that activation loop phosphorylation and the C-terminal hydrophobic motif are essential for high PKB activity in general. On the other hand, we identify membrane targeting, which for decades has been regarded as an essential step in PKB activation, as a mechanism mainly affecting substrate selectivity. Further, we show that PKB activity in cells can be triggered independently of PI3K by initial hydrophobic motif phosphorylation, presumably through a mechanism analogous to other AGC kinases. Importantly, different modes of PKB activation result in phosphorylation of distinct downstream targets. Our data indicate that specific mechanisms have evolved for signaling nodes, like PKB, to select between various downstream events. Targeting such mechanisms selectively could facilitate the development of therapeutics that might limit toxic side effects. PMID:26286748

  3. Phosphatidylserine enhances IKBKAP transcription by activating the MAPK/ERK signaling pathway.

    PubMed

    Donyo, Maya; Hollander, Dror; Abramovitch, Ziv; Naftelberg, Shiran; Ast, Gil

    2016-04-01

    Familial dysautonomia (FD) is a genetic disorder manifested due to abnormal development and progressive degeneration of the sensory and autonomic nervous system. FD is caused by a point mutation in the IKBKAP gene encoding the IKAP protein, resulting in decreased protein levels. A promising potential treatment for FD is phosphatidylserine (PS); however, the manner by which PS elevates IKAP levels has yet to be identified. Analysis of ChIP-seq results of the IKBKAP promoter region revealed binding of the transcription factors CREB and ELK1, which are regulated by the mitogen-activated protein kinase (MAPK)/extracellular-regulated kinase (ERK) signaling pathway. We show that PS treatment enhanced ERK phosphorylation in cells derived from FD patients. ERK activation resulted in elevated IKBKAP transcription and IKAP protein levels, whereas pretreatment with the MAPK inhibitor U0126 blocked elevation of the IKAP protein level. Overexpression of either ELK1 or CREB activated the IKBKAP promoter, whereas downregulation of these transcription factors resulted in a decrease of the IKAP protein. Additionally, we show that PS improves cell migration, known to be enhanced by MAPK/ERK activation and abrogated in FD cells. In conclusion, our results demonstrate that PS activates the MAPK/ERK signaling pathway, resulting in activation of transcription factors that bind the promoter region of IKBKAP and thus enhancing its transcription. Therefore, compounds that activate the MAPK/ERK signaling pathway could constitute potential treatments for FD. PMID:26769675

  4. On the way of classifying new states of active matter

    NASA Astrophysics Data System (ADS)

    Menzel, Andreas M.

    2016-07-01

    With ongoing research into the collective behavior of self-propelled particles, new states of active matter are revealed. Some of them are entirely based on the non-equilibrium character and do not have an immediate equilibrium counterpart. In their recent work, Romanczuk et al (2016 New J. Phys. 18 063015) concentrate on the characterization of smectic-like states of active matter. A new type, referred to by the authors as smectic P, is described. In this state, the active particles form stacked layers and self-propel along them. Identifying and classifying states and phases of non-equilibrium matter, including the transitions between them, is an up-to-date effort that will certainly extend for a longer period into the future.

  5. Signal transducer and activator of transcription 5 is implicated in disease activity in adult and juvenile onset systemic lupus erythematosus.

    PubMed

    Meshaal, Safa; El Refai, Rasha; El Saie, Ahmed; El Hawary, Rabab

    2016-06-01

    The Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway is one of a handful of pleiotropic cascades used to transduce a multitude of signals for development and homeostasis in humans. It is the principal signaling mechanism for a wide array of cytokines and growth factors. Dysregulated cytokine action on immune cells plays an important role in the initiation and progress of systemic lupus erythematosus (SLE). In this study, we tried to assess the role of STAT5 in systemic lupus erythematosus and correlate its phosphorylation level with the disease activity. The activation of the STAT5 was assessed by measuring the level of expression of phosphorylated STAT5 (pSTAT5) using flow cytometry on the peripheral blood T and B cells in 58 SLE patients (40 adult and 18 juvenile onset) and on 23 healthy age- and sex-matched controls for both groups. Serum prolactin level was also assessed in the patients and control by ELISA. The study revealed that the level of pSTAT5 was higher in adult SLE patients than in healthy control (p = 0.001) and in juvenile-onset SLE patients versus age-matched control (p = 0.031). A positive correlation existed between the pSTAT5 levels and Systemic Lupus Activity Measure (SLAM) score and also with multiple clinical manifestations indicating a potential role of STAT5 signaling in pathogenesis SLE. The pSTAT5 signaling is implicated in the disease activity of SLE and may be a useful target of therapy by correcting the dysregulation of cytokines involved in the disease pathogenesis. PMID:27041383

  6. Continuous tooth generation in mouse is induced by activated epithelial Wnt/β-catenin signaling

    PubMed Central

    Järvinen, Elina; Salazar-Ciudad, Isaac; Birchmeier, Walter; Taketo, Makoto M.; Jernvall, Jukka; Thesleff, Irma

    2006-01-01

    The single replacement from milk teeth to permanent teeth makes mammalian teeth different from teeth of most nonmammalian vertebrates and other epithelial organs such as hair and feathers, whose continuous replacement has been linked to Wnt signaling. Here we show that mouse tooth buds expressing stabilized β-catenin in epithelium give rise to dozens of teeth. The molar crowns, however, are typically simplified unicusped cones. We demonstrate that the supernumerary teeth develop by a renewal process where new signaling centers, the enamel knots, bud off from the existing dental epithelium. The basic aspects of the unlocked tooth renewal can be reproduced with a computer model on tooth development by increasing the intrinsic level of activator production, supporting the role of β-catenin pathway as an upstream activator of enamel knot formation. These results may implicate Wnt signaling in tooth renewal, a capacity that was all but lost when mammals evolved progressively more complicated tooth shapes. PMID:17121988

  7. Using activation status of signaling pathways as mechanism-based biomarkers to predict drug sensitivity

    PubMed Central

    Amadoz, Alicia; Sebastian-Leon, Patricia; Vidal, Enrique; Salavert, Francisco; Dopazo, Joaquin

    2015-01-01

    Many complex traits, as drug response, are associated with changes in biological pathways rather than being caused by single gene alterations. Here, a predictive framework is presented in which gene expression data are recoded into activity statuses of signal transduction circuits (sub-pathways within signaling pathways that connect receptor proteins to final effector proteins that trigger cell actions). Such activity values are used as features by a prediction algorithm which can efficiently predict a continuous variable such as the IC50 value. The main advantage of this prediction method is that the features selected by the predictor, the signaling circuits, are themselves rich-informative, mechanism-based biomarkers which provide insight into or drug molecular mechanisms of action (MoA). PMID:26678097

  8. Continuous tooth generation in mouse is induced by activated epithelial Wnt/beta-catenin signaling.

    PubMed

    Järvinen, Elina; Salazar-Ciudad, Isaac; Birchmeier, Walter; Taketo, Makoto M; Jernvall, Jukka; Thesleff, Irma

    2006-12-01

    The single replacement from milk teeth to permanent teeth makes mammalian teeth different from teeth of most nonmammalian vertebrates and other epithelial organs such as hair and feathers, whose continuous replacement has been linked to Wnt signaling. Here we show that mouse tooth buds expressing stabilized beta-catenin in epithelium give rise to dozens of teeth. The molar crowns, however, are typically simplified unicusped cones. We demonstrate that the supernumerary teeth develop by a renewal process where new signaling centers, the enamel knots, bud off from the existing dental epithelium. The basic aspects of the unlocked tooth renewal can be reproduced with a computer model on tooth development by increasing the intrinsic level of activator production, supporting the role of beta-catenin pathway as an upstream activator of enamel knot formation. These results may implicate Wnt signaling in tooth renewal, a capacity that was all but lost when mammals evolved progressively more complicated tooth shapes. PMID:17121988

  9. Electrical Activation of Dark Excitonic States in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Uda, Takushi; Yoshida, Masahiro; Ishii, Akihiro; Kato, Yuichiro K.

    Electrical activation of optical transitions to parity-forbidden dark excitonic states in individual carbon nanotubes is reported. We examine electric field effects on various excitonic states by simultaneously measuring both photocurrent and photoluminescence. As the applied field increases, we observe an emergence of new absorption peaks in the excitation spectra. From the diameter dependence of the energy separation between the new peaks and the ground state of E11 excitons, we attribute the peaks to the dark excited states which became optically active due to the applied field. A simple field-induced exciton dissociation model is introduced to explain the photocurrent threshold fields, and the edge of the E11 continuum states have been identified using this model. Work supported by JSPS (KAKENHI 24340066, 26610080), MEXT (Photon Frontier Network Program, Nanotechnology Platform), Canon Foundation, and Asahi Glass Foundation.

  10. Ultraviolet radiation-induced inflammation activates β-catenin signaling in mouse skin and skin tumors.

    PubMed

    Prasad, Ram; Katiyar, Santosh K

    2014-04-01

    UVB-induced inflammation, in particular the overexpression of cyclooxygenase-2 (COX-2) and prostaglandin (PG) E2, has been implicated in photocarcinogenesis. UVB-induced COX-2 has been associated with β-catenin signaling in keratinocytes. However, a definitive role for COX-2 in the activation of β-catenin signaling as well as its role in UVB-induced skin tumors has not been established. We report that exposure of the skin to UVB resulted in a time- and dose-dependent activation of β-catenin in C3H/HeN mice. This response was COX-2-dependent as UVB-exposed COX-2-deficient mice exhibited significantly lower levels of UVB-induced activation of β-catenin. Moreover, treatment of mice with indomethacin, a COX-2 inhibitor, and an EP2 antagonist inhibited UVB-induced β-catenin signaling. Exposure of SKH-1 hairless mice to UVB radiation (180 mJ/cm2) 3 times a week for 24 weeks resulted in activation of β-catenin signaling in UVB-irradiated skin as well as UVB-induced skin tumors. Concomitantly, the levels of CK1α and GSK-3β, which are responsible for β-catenin signaling, were reduced while the levels of c-Myc and cyclin D1, which are downstream targets of β-catenin, were increased. To further verify the role of UVB-induced inflammation in activation of β-catenin signaling, a high-fat-diet model was used. Administration of high-fat diet exacerbated UVB-induced inflammation. Administration of the high-fat diet enhanced β-catenin signaling and the levels of its downstream targets (c-Myc, cyclin D1, cyclin D2, MMP-2 and MMP-9) in UVB-exposed skin and skin tumors in SKH-1 mice. These data suggest that UV-induced COX-2/PGE2 stimulates β-catenin signaling, and that β-catenin activation may contribute to skin carcinogenesis. PMID:24481495

  11. Wnt signaling activation in adipose progenitors promotes insulin-independent muscle glucose uptake

    PubMed Central

    Zeve, Daniel; Seo, Jin; Suh, Jae Myoung; Stenesen, Drew; Tang, Wei; Berglund, Eric D.; Wan, Yihong; Williams, Linda J.; Lim, Ajin; Martinez, Myrna J.; McKay, Renée M.; Millay, Douglas P.; Olson, Eric N.; Graff, Jonathan M.

    2012-01-01

    SUMMARY Adipose tissues provide circulating nutrients and hormones. We present in vivo mouse studies highlighting roles for Wnt signals in both aspects of metabolism. β-catenin activation in PPARγ–expressing fat progenitors (PBCA) decreased fat mass and induced fibrotic replacement of subcutaneous fat specifically. In spite of lipodystrophy, PBCA mice did not develop the expected diabetes and hepatosteatosis, but rather exhibited improved glucose metabolism and normal insulin sensitivity. Glucose uptake was increased in muscle independently of insulin, associated with cell surface translocation of glucose transporters and AMPK activation. Ex vivo assays showed these effects were likely secondary to blood-borne signals since PBCA sera or conditioned media from PBCA fat progenitors enhanced glucose uptake and activated AMPK in muscle cultures. Thus, adipose progenitor Wnt activation dissociates lipodystrophy from dysfunctional metabolism and highlights a fat-muscle endocrine axis, which may represent a potential therapy to lower blood glucose and improve metabolism. PMID:22482731

  12. Chemical Signals of Synthetic Disaccharide Derivatives Dominate Rhamnolipids at Controlling Multiple Bacterial Activities.

    PubMed

    Singh, Nischal; Shetye, Gauri S; Zheng, Hewen; Sun, Jiayue; Luk, Yan-Yeung

    2016-01-01

    Microbes secrete molecules that modify their environment. Here, we demonstrate a class of synthetic disaccharide derivatives (DSDs) that mimics and dominates the activity of naturally secreted rhamnolipids by Pseudomonas aeruginosa. The DSDs exhibit the dual function of activating and inhibiting the swarming motility through a concentration-dependent activity reversal that is characteristic of signaling molecules. Whereas DSDs tethered with a saturated farnesyl group exhibit inhibition of both biofilm formation and swarming motility, with higher activities than rhamnolipids, a saturated farnesyl tethered with a sulfonate group only inhibits swarming motility but promote biofilm formation. These results identified important structural elements for controlling swarming motility, biofilm formation, and bacterial adhesion and suggest an effective chemical approach to control intertwined signaling processes that are important for biofilm formation and motilities. PMID:26511780

  13. Identification of key residues involved in the activation and signaling properties of dopamine D3 receptor.

    PubMed

    Kota, Kokila; Kuzhikandathil, Eldo V; Afrasiabi, Milad; Lacy, Brett; Kontoyianni, Maria; Crider, A Michael; Song, Daniel

    2015-09-01

    The dopamine D3 receptor exhibits agonist-dependent tolerance and slow response termination (SRT) signaling properties that distinguish it from the closely-related D2 receptors. While amino acid residues important for D3 receptor ligand binding have been identified, the residues involved in activation of D3 receptor signaling and induction of signaling properties have not been determined. In this paper, we used cis and trans isomers of a novel D3 receptor agonist, 8-OH-PBZI, and site-directed mutagenesis to identify key residues involved in D3 receptor signaling function. Our results show that trans-8-OH-PBZI, but not cis-8-OH-PBZI, elicit the D3 receptor tolerance and SRT properties. We show that while both agonists require a subset of residues in the orthosteric binding site of D3 receptors for activation of the receptor, the ability of the two isomers to differentially induce tolerance and SRT is mediated by interactions with specific residues in the sixth transmembrane helix and third extracellular loop of the D3 receptor. We also show that unlike cis-8-OH-PBZI, which is a partial agonist at the dopamine D2S receptor and full agonist at dopamine D2L receptor, trans-8-OH-PBZI is a full agonist at both D2S and D2L receptors. The different effect of the two isomers on D3 receptor signaling properties and D2S receptor activation correlated with differential effects of the isomers on agonist-induced mouse locomotor activity. The two isomers of 8-OH-PBZI represent novel pharmacological tools for in silico D3 and D2 receptor homology modeling and for determining the role of D3 receptor tolerance and SRT properties in signaling and behavior. PMID:26116441

  14. Pressure is not a state function for generic active fluids

    NASA Astrophysics Data System (ADS)

    Solon, A. P.; Fily, Y.; Baskaran, A.; Cates, M. E.; Kafri, Y.; Kardar, M.; Tailleur, J.

    2015-08-01

    Pressure is the mechanical force per unit area that a confined system exerts on its container. In thermal equilibrium, it depends only on bulk properties--such as density and temperature--through an equation of state. Here we show that in a wide class of active systems the pressure depends on the precise interactions between the active particles and the confining walls. In general, therefore, active fluids have no equation of state. Their mechanical pressure exhibits anomalous properties that defy the familiar thermodynamic reasoning that holds in equilibrium. The pressure remains a function of state, however, in some specific and well-studied active models that tacitly restrict the character of the particle-wall and/or particle-particle interactions.

  15. Long-range intramolecular signaling in a tRNA synthetase complex revealed by pre-steady-state kinetics.

    PubMed

    Uter, Nathan T; Perona, John J

    2004-10-01

    Pre-steady-state kinetic studies of Escherichia coli glutaminyl-tRNA synthetase conclusively demonstrate the existence of long-distance pathways of communication through the protein-RNA complex. Measurements of aminoacyl-tRNA synthesis reveal a rapid burst of product formation followed by a slower linear increase corresponding to k(cat). Thus, a step after chemistry but before regeneration of active enzyme is rate-limiting for synthesis of Gln-tRNA(Gln). Single-turnover kinetics validates these observations, confirming that the rate of the chemical step for tRNA aminoacylation (k(chem)) exceeds the steady-state rate by nearly 10-fold. The concentration dependence of the single-turnover reaction further reveals that the glutamine K(d) is significantly higher than the steady-state K(m) value. The separation of binding from catalytic events by transient kinetics now allows precise interpretation of how alterations in tRNA structure affect the aminoacylation reaction. Mutation of U35 in the tRNA anticodon loop decreases k(chem) by 30-fold and weakens glutamine binding affinity by 20-fold, demonstrating that the active-site configuration depends on enzyme-tRNA contacts some 40 A distant. By contrast, mutation of the adjacent G36 has very small effects on k(chem) and K(d) for glutamine. Together with x-ray crystallographic data, these findings allow a comparative evaluation of alternative long-range signaling pathways and lay the groundwork for systematic exploration of how induced-fit conformational transitions may control substrate selection in this model enzyme-RNA complex. PMID:15452355

  16. Reduced endogenous Ca2+ buffering speeds active zone Ca2+ signaling.

    PubMed

    Delvendahl, Igor; Jablonski, Lukasz; Baade, Carolin; Matveev, Victor; Neher, Erwin; Hallermann, Stefan

    2015-06-01

    Fast synchronous neurotransmitter release at the presynaptic active zone is triggered by local Ca(2+) signals, which are confined in their spatiotemporal extent by endogenous Ca(2+) buffers. However, it remains elusive how rapid and reliable Ca(2+) signaling can be sustained during repetitive release. Here, we established quantitative two-photon Ca(2+) imaging in cerebellar mossy fiber boutons, which fire at exceptionally high rates. We show that endogenous fixed buffers have a surprisingly low Ca(2+)-binding ratio (∼ 15) and low affinity, whereas mobile buffers have high affinity. Experimentally constrained modeling revealed that the low endogenous buffering promotes fast clearance of Ca(2+) from the active zone during repetitive firing. Measuring Ca(2+) signals at different distances from active zones with ultra-high-resolution confirmed our model predictions. Our results lead to the concept that reduced Ca(2+) buffering enables fast active zone Ca(2+) signaling, suggesting that the strength of endogenous Ca(2+) buffering limits the rate of synchronous synaptic transmission. PMID:26015575

  17. Jasmonate signaling in plant stress responses and development - active and inactive compounds.

    PubMed

    Wasternack, Claus; Strnad, Miroslav

    2016-09-25

    Jasmonates (JAs) are lipid-derived signals mediating plant responses to biotic and abiotic stresses and in plant development. Following the elucidation of each step in their biosynthesis and the important components of perception and signaling, several activators, repressors and co-repressors have been identified which contribute to fine-tuning the regulation of JA-induced gene expression. Many of the metabolic reactions in which JA participates, such as conjugation with amino acids, glucosylation, hydroxylation, carboxylation, sulfation and methylation, lead to numerous compounds with different biological activities. These metabolites may be highly active, partially active in specific processes or inactive. Hydroxylation, carboxylation and sulfation inactivate JA signaling. The precursor of JA biosynthesis, 12-oxo-phytodienoic acid (OPDA), has been identified as a JA-independent signaling compound. An increasing number of OPDA-specific processes is being identified. To conclude, the numerous JA compounds and their different modes of action allow plants to respond specifically and flexibly to alterations in the environment. PMID:26581489

  18. ASBESTOS-INDUCED ACTIVATION OF SIGNALING PATHWAYS IN HUMAN BRONCHIAL EPITHELIAL CELLS

    EPA Science Inventory

    Title: Asbestos-Induced Activation of Signaling Pathways in Human
    Bronchial Epithelial Cells

    X. Wang, MD 1, J. M. Samet, PhD 2 and A. J. Ghio, MD 2. 1 Center for
    Environmental Medicine, Asthma and Lung Biology, University of North
    Carolina, Chapel Hill, NC, Uni...

  19. 78 FR 28801 - Foreign-Trade Zone 117-Orange, TX, Authorization of Production Activity, Signal International...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-16

    ... notice in the Federal Register inviting public comment (78 FR 4383, 1-22-2013). The FTZ Board has... Foreign-Trade Zones Board Foreign-Trade Zone 117--Orange, TX, Authorization of Production Activity, Signal International Texas GP, LLC (Shipbuilding), Orange, TX On January 10, 2013, the Foreign Trade Zone of...

  20. Epigenetic regulator Lid maintains germline stem cells through regulating JAK-STAT signaling pathway activity

    PubMed Central

    Tarayrah, Lama; Li, Yuping; Gan, Qiang; Chen, Xin

    2015-01-01

    ABSTRACT Signaling pathways and epigenetic mechanisms have both been shown to play essential roles in regulating stem cell activity. While the role of either mechanism in this regulation is well established in multiple stem cell lineages, how the two mechanisms interact to regulate stem cell activity is not as well understood. Here we report that in the Drosophila testis, an H3K4me3-specific histone demethylase encoded by little imaginal discs (lid) maintains germline stem cell (GSC) mitotic index and prevents GSC premature differentiation. Lid is required in germ cells for proper expression of the Stat92E transcription factor, the downstream effector of the Janus kinase signal transducer and activator of transcription (JAK-STAT) signaling pathway. Our findings support a germ cell autonomous role for the JAK-STAT pathway in maintaining GSCs and place Lid as an upstream regulator of this pathway. Our study provides new insights into the biological functions of a histone demethylase in vivo and sheds light on the interaction between epigenetic mechanisms and signaling pathways in regulating stem cell activities. PMID:26490676

  1. 78 FR 4383 - Foreign-Trade Zone 117-Orange, Texas; Notification of Proposed Production Activity; Signal...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE Foreign-Trade Zones Board Foreign-Trade Zone 117--Orange, Texas; Notification of Proposed Production Activity; Signal International Texas GP, LLC (Shipbuilding), Orange, TX The Foreign Trade Zone of Southeast Texas, Inc., grantee of FTZ 117, submitted...

  2. Reduced endogenous Ca2+ buffering speeds active zone Ca2+ signaling

    PubMed Central

    Delvendahl, Igor; Jablonski, Lukasz; Baade, Carolin; Matveev, Victor; Neher, Erwin; Hallermann, Stefan

    2015-01-01

    Fast synchronous neurotransmitter release at the presynaptic active zone is triggered by local Ca2+ signals, which are confined in their spatiotemporal extent by endogenous Ca2+ buffers. However, it remains elusive how rapid and reliable Ca2+ signaling can be sustained during repetitive release. Here, we established quantitative two-photon Ca2+ imaging in cerebellar mossy fiber boutons, which fire at exceptionally high rates. We show that endogenous fixed buffers have a surprisingly low Ca2+-binding ratio (∼15) and low affinity, whereas mobile buffers have high affinity. Experimentally constrained modeling revealed that the low endogenous buffering promotes fast clearance of Ca2+ from the active zone during repetitive firing. Measuring Ca2+ signals at different distances from active zones with ultra-high-resolution confirmed our model predictions. Our results lead to the concept that reduced Ca2+ buffering enables fast active zone Ca2+ signaling, suggesting that the strength of endogenous Ca2+ buffering limits the rate of synchronous synaptic transmission. PMID:26015575

  3. Endogenous heparan sulfate and heparin modulate bone morphogenetic protein-4 signaling and activity.

    PubMed

    Khan, Shaukat A; Nelson, Matthew S; Pan, Chendong; Gaffney, Patrick M; Gupta, Pankaj

    2008-06-01

    Bone morphogenetic proteins (BMPs) and their endogenous antagonists are important for brain and bone development and tumor initiation and progression. Heparan sulfate (HS) proteoglycans (HSPG) modulate the activities of BMPs and their antagonists. How glycosaminoglycans (GAGs) influence BMP activity in various malignancies and in inherited abnormalities of GAG metabolism, and the structural features of GAGs essential for modulation of BMP signaling, remain incompletely defined. We examined whether chemically modified soluble heparins, the endogenous HS in malignant cells and the HS accumulated in Hurler syndrome cells influence BMP-4 signaling and activity. We show that both exogenous (soluble) and endogenous GAGs modulate BMP-4 signaling and activity, and that this effect is dependent on specific sulfate residues of GAGs. Our studies suggest that endogenous sulfated GAGs promote the proliferation and impair differentiation of malignant human cells, providing the rationale for investigating whether pharmacological agents that inhibit GAG synthesis or function might reverse this effect. Our demonstration of impairment of BMP-4 signaling by GAGs in multipotent stem cells in human Hurler syndrome identifies a mechanism that might contribute to the progressive neurological and skeletal abnormalities in Hurler syndrome and related mucopolysaccharidoses. PMID:18385288

  4. Electrochemical detection of protein kinase activity based on carboxypeptidase Y digestion triggered signal amplification.

    PubMed

    Yin, Huanshun; Wang, Xinxu; Guo, Yunlong; Zhou, Yunlei; Ai, Shiyun

    2015-04-15

    An effective assay method for monitoring protein kinase activity and screening inhibitors is greatly beneficial to kinase-related drug discovery, early diagnosis of diseases, and therapeutic effect evaluation. Herein, we develop a simple electrochemical method for detecting the activity of casein kinase II (CK2) based on phosphorylation against carboxypeptidase Y (CPY) digestion triggered signal amplification, where CK2 catalyzed phosphorylation event protects the substrate peptide from the digestion of CPY, maintains the repulsive force of the substrate peptide towards the redox probe, and results in a weak electrochemical signal. Whereas, without phosphorylation, the substrate peptide is digested by CPY and a strong electrochemical signal is obtained. The detection feasibility is demonstrated for the assay of CK2 activity with low detection limit of 0.047unit/mL. Moreover, the biosensor was used for the analysis of kinase inhibition. Based on the electrochemical signal dependent inhibitor concentration, the IC50 value of ellagic acid was estimated to be 39.77nM. The proposed method is also successfully applied to analyze CK2 activity in cell lysates, proving the applicability in complex biological samples. PMID:25460885

  5. Phyllostachys edulis extract induces apoptosis signaling in osteosarcoma cells, associated with AMPK activation

    PubMed Central

    Chou, Chi-Wen; Cheng, Ya-Wen; Tsai, Chung-Hung

    2014-01-01

    Objective Bamboo is distributed worldwide, and its different parts are used as foods or as a traditional herb. Recently, antitumoral effects of bamboo extracts on several tumors have been increasingly reported; however, antitumoral activity of bamboo extracts on osteosarcoma remains unclear. In the present study, we investigated effects of an aqueous Phyllostachys edulis leaf extract (PEE) on osteosarcoma cells and the underlying mechanism of inhibition. Methods The growth of human osteosarcoma cell lines 143B and MG-63 and lung fibroblast MRC-5 cells was determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Apoptosis was demonstrated using TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay and flow cytometric analysis. Phosphorylation and protein levels were determined by immunoblotting. Results After treatment with PEE, viability of 143B and MG-63 cells was dose-dependently reduced to 36.3%±1.6% of control values, which were similar to AICAR (5-aminoimidazole-4-carboxamide 1-β-D-ribofuranoside) treatments. In parallel, ratios of apoptotic cells and cells in the sub-G1 phase were significantly increased. Further investigation showed that PEE treatments led to activation of caspase cascades and changes of apoptotic mediators Bcl2, Bax, and p53. Consistently, our results revealed that PEE activated adenosine monophosphate-activated protein kinase (AMPK) signaling, and the AMPK activation was associated with the induction of apoptotic signaling. Conclusion Our results indicated that PEE suppressed the growth of 143B and MG-63 cells but moderately affected MRC-5 cells. PEE-induced apoptosis may attribute to AMPK activation and the following activation of apoptotic signaling cascades. These findings revealed that PEE possesses antitumoral activity on human osteosarcoma cells by manipulating AMPK signaling, suggesting that PEE alone or combined with regular antitumor drugs may be beneficial as osteosarcoma

  6. State-dependent signaling by Cav1.2 regulates hair follicle stem cell function.

    PubMed

    Yucel, Gozde; Altindag, Banu; Gomez-Ospina, Natalia; Rana, Anshul; Panagiotakos, Georgia; Lara, Maria Fernanda; Dolmetsch, Ricardo; Oro, Anthony E

    2013-06-01

    The signals regulating stem cell activation during tissue regeneration remain poorly understood. We investigated the baldness associated with mutations in the voltage-gated calcium channel (VGCC) Cav1.2 underlying Timothy syndrome (TS). While hair follicle stem cells express Cav1.2, they lack detectable voltage-dependent calcium currents. Cav1.2(TS) acts in a dominant-negative manner to markedly delay anagen, while L-type channel blockers act through Cav1.2 to induce anagen and overcome the TS phenotype. Cav1.2 regulates production of the bulge-derived BMP inhibitor follistatin-like1 (Fstl1), derepressing stem cell quiescence. Our findings show how channels act in nonexcitable tissues to regulate stem cells and may lead to novel therapeutics for tissue regeneration. PMID:23752588

  7. Robustness of cortical topography across fields, laminae, anesthetic states, and neurophysiological signal types.

    PubMed

    Guo, Wei; Chambers, Anna R; Darrow, Keith N; Hancock, Kenneth E; Shinn-Cunningham, Barbara G; Polley, Daniel B

    2012-07-01

    Topographically organized maps of the sensory receptor epithelia are regarded as cornerstones of cortical organization as well as valuable readouts of diverse biological processes ranging from evolution to neural plasticity. However, maps are most often derived from multiunit activity recorded in the thalamic input layers of anesthetized animals using near-threshold stimuli. Less distinct topography has been described by studies that deviated from the formula above, which brings into question the generality of the principle. Here, we explicitly compared the strength of tonotopic organization at various depths within core and belt regions of the auditory cortex using electrophysiological measurements ranging from single units to delta-band local field potentials (LFP) in the awake and anesthetized mouse. Unit recordings in the middle cortical layers revealed a precise tonotopic organization in core, but not belt, regions of auditory cortex that was similarly robust in awake and anesthetized conditions. In core fields, tonotopy was degraded outside the middle layers or when LFP signals were substituted for unit activity, due to an increasing proportion of recording sites with irregular tuning for pure tones. However, restricting our analysis to clearly defined receptive fields revealed an equivalent tonotopic organization in all layers of the cortical column and for LFP activity ranging from gamma to theta bands. Thus, core fields represent a transition between topographically organized simple receptive field arrangements that extend throughout all layers of the cortical column and the emergence of nontonotopic representations outside the input layers that are further elaborated in the belt fields. PMID:22764225

  8. Robustness of cortical topography across fields, laminae, anesthetic states, and neurophysiological signal types

    PubMed Central

    Guo, Wei; Chambers, Anna R.; Darrow, Keith N.; Hancock, Kenneth E.; Shinn-Cunningham, Barbara G.; Polley, Daniel B.

    2012-01-01

    Topographically organized maps of the sensory receptor epithelia are regarded as cornerstones of cortical organization as well as valuable readouts of diverse biological processes ranging from evolution to neural plasticity. However, maps are most often derived from multiunit activity recorded in the thalamic input layers of anesthetized animals using near-threshold stimuli. Less distinct topography has been described by studies that deviated from the formula above, which brings into question the generality of the principle. Here, we explicitly compared the strength of tonotopic organization at various depths within core and belt regions of the auditory cortex using electrophysiological measurements ranging from single units to delta-band local field potentials (LFP) in the awake and anesthetized mouse. Unit recordings in the middle cortical layers revealed a precise tonotopic organization in core, but not belt, regions of auditory cortex that was similarly robust in awake and anesthetized conditions. In core fields, tonotopy was degraded outside the middle layers or when LFP signals were substituted for unit activity, due to an increasing proportion of recording sites with irregular tuning for pure tones. However, restricting our analysis to clearly defined receptive fields revealed an equivalent tonotopic organization in all layers of the cortical column and for LFP activity ranging from gamma to theta bands. Thus, core fields represent a transition between topographically organized simple receptive field arrangements that extend throughout all layers of the cortical column and the emergence of non-tonotopic representations outside the input layers that are further elaborated in the belt fields. PMID:22764225

  9. The interferon signaling antagonist function of yellow fever virus NS5 protein is activated by Type I interferon

    PubMed Central

    Rajsbaum, Ricardo; Macleod, Jesica M. Levingston; Pisanelli, Giuseppe; Pham, Alissa; Ayllon, Juan; Miorin, Lisa; Martinez, Carles; tenOever, Benjamin R; García-Sastre, Adolfo

    2014-01-01

    Summary To successfully establish infection Flaviviruses have to overcome the antiviral state induced by type I interferon (IFN-I). The nonstructural NS5 proteins of several flaviviruses antagonize IFN-I signaling. Here we show that yellow fever virus (YFV) inhibits IFN-I signaling through a unique mechanism that involves binding of YFV NS5 to the IFN-activated transcription factor STAT2 only in cells that have been stimulated with IFN-I. This NS5-STAT2 interaction requires IFN-I-induced tyrosine phosphorylation of STAT1 and the K63-linked polyubiquitination at a lysine in the N-terminal region of YFV NS5. We identified TRIM23 as the E3 ligase that interacts with and polyubiquitinates YFV NS5 to promote its binding to STAT2 and trigger IFN-I signaling inhibition. Our results demonstrate the importance of YFV NS5 in overcoming the antiviral action of IFN-I and offer a unique example of a viral protein that is activated by the same host pathway that it inhibits. PMID:25211074

  10. Cadmium Activates Multiple Signaling Pathways That Coordinately Stimulate Akt Activity to Enhance c-Myc mRNA Stability

    PubMed Central

    Tsai, Jia-Shiuan; Chao, Cheng-Han; Lin, Lih-Yuan

    2016-01-01

    Cadmium is a known environmental carcinogen. Exposure of Cd leads to the activation of several proto-oncogenes in cells. We investigated here the mechanism of c-Myc expression in hepatic cells under Cd treatment. The c-Myc protein and mRNA levels increased in dose- and time-dependent manners in HepG2 cells with Cd treatment. This increase was due to an increase in c-Myc mRNA stability. To explore the mechanism involved in enhancing the mRNA stability, several cellular signaling factors that evoked by Cd treatment were analyzed. PI3K, p38, ERK and JNK were activated by Cd. However, ERK did not participate in the Cd-induced c-Myc expression. Further analysis revealed that mTORC2 was a downstream factor of p38. PI3K, JNK and mTORC2 coordinately activated Akt. Akt was phosphorylated at Thr450 in the untreated cells. Cd treatment led to additional phosphorylation at Thr308 and Ser473. Blocking any of the three signaling factors resulted in the reduction of phosphorylation level at all three Akt sites. The activated Akt phosphorylated Foxo1 and allowed the modified protein to translocate into the cytoplasm. We conclude that Cd-induced accumulation of c-Myc requires the activation of several signaling pathways. The signals act coordinately for Akt activation and drive the Foxo1 from the nucleus to the cytoplasm. Reduction of Foxo1 in the nucleus reduces the transcription of its target genes that may affect c-Myc mRNA stability, resulting in a higher accumulation of the c-Myc proteins. PMID:26751215

  11. Ventral Tegmental Area Neurotensin Signaling Links the Lateral Hypothalamus to Locomotor Activity and Striatal Dopamine Efflux in Male Mice

    PubMed Central

    Patterson, Christa M.; Wong, Jenny-Marie T.; Leinninger, Gina M.; Allison, Margaret B.; Mabrouk, Omar S.; Kasper, Chelsea L.; Gonzalez, Ian E.; Mackenzie, Alexander; Jones, Justin C.

    2015-01-01

    Projections from the lateral hypothalamic area (LHA) innervate components of the mesolimbic dopamine (MLDA) system, including the ventral tegmental area (VTA) and nucleus accumbens (NAc), to modulate motivation appropriately for physiologic state. Neurotensin (NT)-containing LHA neurons respond to multiple homeostatic challenges and project to the VTA, suggesting that these neurons could link such signals to MLDA function. Indeed, we found that pharmacogenetic activation of LHA NT neurons promoted prolonged DA-dependent locomotor activity and NAc DA efflux, suggesting the importance of VTA neurotransmitter release by LHA NT neurons for the control of MLDA function. Using a microdialysis-mass spectrometry technique that we developed to detect endogenous NT in extracellular fluid in the mouse brain, we found that activation of LHA NT cells acutely increased the extracellular concentration of NT (a known activator of VTA DA cells) in the VTA. In contrast to the prolonged elevation of extracellular NAc DA, however, VTA NT concentrations rapidly returned to baseline. Intra-VTA infusion of NT receptor antagonist abrogated the ability of LHA NT cells to increase extracellular DA in the NAc, demonstrating that VTA NT promotes NAc DA release. Thus, transient LHA-derived NT release in the VTA couples LHA signaling to prolonged changes in DA efflux and MLDA function. PMID:25734363

  12. Resting state activity in patients with disorders of consciousness

    PubMed Central

    Soddu, Andrea; Vanhaudenhuyse, Audrey; Demertzi, Athena; Bruno, Marie-Aurélie; Tshibanda, Luaba; Di, Haibo; Boly, Mélanie; Papa, Michele; Laureys, Steven; Noirhomme, Quentin

    Summary Recent advances in the study of spontaneous brain activity have demonstrated activity patterns that emerge with no task performance or sensory stimulation; these discoveries hold promise for the study of higher-order associative network functionality. Additionally, such advances are argued to be relevant in pathological states, such as disorders of consciousness (DOC), i.e., coma, vegetative and minimally conscious states. Recent studies on resting state activity in DOC, measured with functional magnetic resonance imaging (fMRI) techniques, show that functional connectivity is disrupted in the task-negative or the default mode network. However, the two main approaches employed in the analysis of resting state functional connectivity data (i.e., hypothesis-driven seed-voxel and data-driven independent component analysis) present multiple methodological difficulties, especially in non-collaborative DOC patients. Improvements in motion artifact removal and spatial normalization are needed before fMRI resting state data can be used as proper biomarkers in severe brain injury. However, we anticipate that such developments will boost clinical resting state fMRI studies, allowing for easy and fast acquisitions and ultimately improve the diagnosis and prognosis in the absence of DOC patients’ active collaboration in data acquisition. PMID:21693087

  13. Resting state activity in patients with disorders of consciousness.

    PubMed

    Soddu, Andrea; Vanhaudenhuyse, Audrey; Demertzi, Athena; Bruno, Marie-Aurélie; Tshibanda, Luaba; Di, Haibo; Mélanie, Boly; Papa, Michele; Laureys, Steven; Noirhomme, Quentin

    2011-01-01

    Recent advances in the study of spontaneous brain activity have demonstrated activity patterns that emerge with no task performance or sensory stimulation; these discoveries hold promise for the study of higher-order associative network functionality. Additionally, such advances are argued to be relevant in pathological states, such as disorders of consciousness (DOC), i.e., coma, vegetative and minimally conscious states. Recent studies on resting state activity in DOC, measured with functional magnetic resonance imaging (fMRI) techniques, show that functional connectivity is disrupted in the task-negative or the default mode network. However, the two main approaches employed in the analysis of resting state functional connectivity data (i.e., hypothesis-driven seed-voxel and data-driven independent component analysis) present multiple methodological difficulties, especially in non-collaborative DOC patients. Improvements in motion artifact removal and spatial normalization are needed before fMRI resting state data can be used as proper biomarkers in severe brain injury. However, we anticipate that such developments will boost clinical resting state fMRI studies, allowing for easy and fast acquisitions and ultimately improve the diagnosis and prognosis in the absence of DOC patients' active collaboration in data acquisition. PMID:21693087

  14. mTOR signaling promotes stem cell activation via counterbalancing BMP-mediated suppression during hair regeneration.

    PubMed

    Deng, Zhili; Lei, Xiaohua; Zhang, Xudong; Zhang, Huishan; Liu, Shuang; Chen, Qi; Hu, Huimin; Wang, Xinyue; Ning, Lina; Cao, Yujing; Zhao, Tongbiao; Zhou, Jiaxi; Chen, Ting; Duan, Enkui

    2015-02-01

    Hair follicles (HFs) undergo cycles of degeneration (catagen), rest (telogen), and regeneration (anagen) phases. Anagen begins when the hair follicle stem cells (HFSCs) obtain sufficient activation cues to overcome suppressive signals, mainly the BMP pathway, from their niche cells. Here, we unveil that mTOR complex 1 (mTORC1) signaling is activated in HFSCs, which coincides with the HFSC activation at the telogen-to-anagen transition. By using both an inducible conditional gene targeting strategy and a pharmacological inhibition method to ablate or inhibit mTOR signaling in adult skin epithelium before anagen initiation, we demonstrate that HFs that cannot respond to mTOR signaling display significantly delayed HFSC activation and extended telogen. Unexpectedly, BMP signaling activity is dramatically prolonged in mTOR signaling-deficient HFs. Through both gain- and loss-of-function studies in vitro, we show that mTORC1 signaling negatively affects BMP signaling, which serves as a main mechanism whereby mTORC1 signaling facilitates HFSC activation. Indeed, in vivo suppression of BMP by its antagonist Noggin rescues the HFSC activation defect in mTORC1-null skin. Our findings reveal a critical role for mTOR signaling in regulating stem cell activation through counterbalancing BMP-mediated repression during hair regeneration. PMID:25609845

  15. Toll-like receptor 9 trafficking and signaling for type I interferons requires PIKfyve activity.

    PubMed

    Hayashi, Kachiko; Sasai, Miwa; Iwasaki, Akiko

    2015-09-01

    Toll-like receptors (TLRs) traffic to distinct membranes for signaling. TLR7 and TLR9 recognize viral nucleic acids in the endosomes and induce robust anti-viral program. Signaling from these TLRs bifurcate at the level of distinct endosomal compartments, namely VAMP3(+) and LAMP(+) endosomes, to mediate the induction of cytokine and type I interferon (IFN) genes, respectively. The formation of the TLR9 endosome competent for IFNs induction requires AP-3. Phosphoinositides (PIs) mark distinct subcellular membranes and control membrane trafficking. However, their role in TLR trafficking and signaling in different dendritic cell (DC) subsets remains unclear. Here, we examined the role of phosphatidylinositol 3P 5-kinase, PIKfyve, in TLR9 trafficking and signaling. We demonstrate that inhibition of PIKfyve activity preferentially blocks TLR9 signaling for type I IFN induction in FLT3L-bone marrow-derived DCs. By confocal microscopy using RAW264.7 cells, we show that trafficking of both TLR9 and CpG to the LAMP1(+) compartment was blocked by PIKfyve inhibitor treatment, whereas their trafficking to the VAMP3(+) endosome remained intact. Further, AP-3 recruitment to TLR9 endosomes was impaired by PIKfyve inhibition. These data indicate that PIKfyve provides critical PIs necessary for the formation of endosome from which TLR9 signals to induce type I IFNs. PMID:25925170

  16. Zinc Chloride Transiently Maintains Mouse Embryonic Stem Cell Pluripotency by Activating Stat3 Signaling

    PubMed Central

    Hu, Jing; Yang, Zhiyong; Wang, Jinbo; Yu, Jia; Guo, Jing; Liu, Shiying; Qian, Chunmei; Song, Liwen; Wu, Yi; Cheng, Jiajing

    2016-01-01

    An improved understanding of the pluripotency maintenance of embryonic stem (ES) cells is important for investigations of early embryo development and for cell replacement therapy, but the mechanism behind pluripotency is still incompletely understood. Recent findings show that zinc, an essential trace element in humans, is critically involved in regulating various signaling pathways and genes expression. However, its role in ES cell fate determination remains to be further explored. Here we showed that 2μM zinc chloride (ZnCl2) transiently maintained mouse ES cell pluripotency in vitro. The cultured mouse ES cells remained undifferentiated under 2μM ZnCl2 treatment in leukemia inhibitory factor (LIF) withdrawal, retinoic acid (RA) or embryoid bodies (EBs) differentiation assays. In addition, ZnCl2 increased pluripotency genes expression and inhibited differentiation genes expression. Further mechanistic studies revealed that ZnCl2 transiently activated signal transducers and activators of transcription 3 (Stat3) signaling through promoting Stat3 phosphorylation. Inhibition of Stat3 signaling abrogated the effects of ZnCl2 on mouse ES cell pluripotency. Taken together, this study demonstrated a critical role of zinc in the pluripotency maintenance of mouse ES cells, as well as an important regulator of Stat3 signaling. PMID:26910359

  17. Dishevelled attenuates the repelling activity of Wnt signaling during neurite outgrowth in Caenorhabditis elegans.

    PubMed

    Zheng, Chaogu; Diaz-Cuadros, Margarete; Chalfie, Martin

    2015-10-27

    Wnt proteins regulate axonal outgrowth along the anterior-posterior axis, but the intracellular mechanisms that modulate the strength of Wnt signaling in axon guidance are largely unknown. Using the Caenorhabditis elegans mechanosensory PLM neurons, we found that posteriorly enriched LIN-44/Wnt acts as a repellent to promote anteriorly directed neurite outgrowth through the LIN-17/Frizzled receptor, instead of controlling neuronal polarity as previously thought. Dishevelled (Dsh) proteins DSH-1 and MIG-5 redundantly mediate the repulsive activity of the Wnt signals to induce anterior outgrowth, whereas DSH-1 also provides feedback inhibition to attenuate the signaling to allow posterior outgrowth against the Wnt gradient. This inhibitory function of DSH-1, which requires its dishevelled, Egl-10, and pleckstrin (DEP) domain, acts by promoting LIN-17 phosphorylation and is antagonized by planar cell polarity signaling components Van Gogh (VANG-1) and Prickle (PRKL-1). Our results suggest that Dsh proteins both respond to Wnt signals to shape neuronal projections and moderate its activity to fine-tune neuronal morphology. PMID:26460008

  18. Quorum activation at a distance: spatiotemporal patterns of gene regulation from diffusion of an autoinducer signal

    NASA Astrophysics Data System (ADS)

    Dilanji, Gabriel; Langebrake, Jessica; Deleenheer, Patrick; Hagen, Stephen J.

    2012-02-01

    Bacteria in colonies coordinate gene regulation through the exchange of diffusible signal molecules known as autoinducers (AI). This ``quorum signaling'' often occurs in physically heterogeneous and spatially extended environments such as biofilms. Under these conditions the space and time scales for diffusion of the signal limit the range and timing of effective gene regulation. We expect that spatial and temporal patterns of gene expression will reflect physical environmental constraints as well as nonlinear transcriptional activation and feedback within the gene regulatory system. We have combined experiments and modeling to investigate how these spatiotemporal patterns develop. We embed engineered plasmid/GFP quorum sensor strains or wild type strains in a long narrow agar lane, and then introduce AI signal at one terminus of the lane. Diffusion of the AI initiates reporter expression along the length of the lane, extending to macroscopic distances of mm-cm. Resulting patterns are captured quantitatively by a mathematical model that incorporates logistic growth of the population, diffusion of AI, and nonlinear transcriptional activation. Our results show that a diffusing quorum signal can coordinate gene expression over distances of order 1cm on time scales of order 10 hrs.

  19. Dishevelled attenuates the repelling activity of Wnt signaling during neurite outgrowth in Caenorhabditis elegans

    PubMed Central

    Zheng, Chaogu; Diaz-Cuadros, Margarete; Chalfie, Martin

    2015-01-01

    Wnt proteins regulate axonal outgrowth along the anterior–posterior axis, but the intracellular mechanisms that modulate the strength of Wnt signaling in axon guidance are largely unknown. Using the Caenorhabditis elegans mechanosensory PLM neurons, we found that posteriorly enriched LIN-44/Wnt acts as a repellent to promote anteriorly directed neurite outgrowth through the LIN-17/Frizzled receptor, instead of controlling neuronal polarity as previously thought. Dishevelled (Dsh) proteins DSH-1 and MIG-5 redundantly mediate the repulsive activity of the Wnt signals to induce anterior outgrowth, whereas DSH-1 also provides feedback inhibition to attenuate the signaling to allow posterior outgrowth against the Wnt gradient. This inhibitory function of DSH-1, which requires its dishevelled, Egl-10, and pleckstrin (DEP) domain, acts by promoting LIN-17 phosphorylation and is antagonized by planar cell polarity signaling components Van Gogh (VANG-1) and Prickle (PRKL-1). Our results suggest that Dsh proteins both respond to Wnt signals to shape neuronal projections and moderate its activity to fine-tune neuronal morphology. PMID:26460008

  20. Organ-specific adaptive signaling pathway activation in metastatic breast cancer cells

    PubMed Central

    Burnett, Riesa M.; Craven, Kelly E.; Krishnamurthy, Purna; Goswami, Chirayu P.; Badve, Sunil; Crooks, Peter; Mathews, William P.; Bhat-Nakshatri, Poornima; Nakshatri, Harikrishna

    2015-01-01

    Breast cancer metastasizes to bone, visceral organs, and/or brain depending on the subtype, which may involve activation of a host organ-specific signaling network in metastatic cells. To test this possibility, we determined gene expression patterns in MDA-MB-231 cells and its mammary fat pad tumor (TMD-231), lung-metastasis (LMD-231), bone-metastasis (BMD-231), adrenal-metastasis (ADMD-231) and brain-metastasis (231-BR) variants. When gene expression between metastases was compared, 231-BR cells showed the highest gene expression difference followed by ADMD-231, LMD-231, and BMD-231 cells. Neuronal transmembrane proteins SLITRK2, TMEM47, and LYPD1 were specifically overexpressed in 231-BR cells. Pathway-analyses revealed activation of signaling networks that would enable cancer cells to adapt to organs of metastasis such as drug detoxification/oxidative stress response/semaphorin neuronal pathway in 231-BR, Notch/orphan nuclear receptor signals involved in steroidogenesis in ADMD-231, acute phase response in LMD-231, and cytokine/hematopoietic stem cell signaling in BMD-231 cells. Only NF-κB signaling pathway activation was common to all except BMD-231 cells. We confirmed NF-κB activation in 231-BR and in a brain metastatic variant of 4T1 cells (4T1-BR). Dimethylaminoparthenolide inhibited NF-κB activity, LYPD1 expression, and proliferation of 231-BR and 4T1-BR cells. Thus, transcriptome change enabling adaptation to host organs is likely one of the mechanisms associated with organ-specific metastasis and could potentially be targeted therapeutically. PMID:25926557

  1. Organ-specific adaptive signaling pathway activation in metastatic breast cancer cells.

    PubMed

    Burnett, Riesa M; Craven, Kelly E; Krishnamurthy, Purna; Goswami, Chirayu P; Badve, Sunil; Crooks, Peter; Mathews, William P; Bhat-Nakshatri, Poornima; Nakshatri, Harikrishna

    2015-05-20

    Breast cancer metastasizes to bone, visceral organs, and/or brain depending on the subtype, which may involve activation of a host organ-specific signaling network in metastatic cells. To test this possibility, we determined gene expression patterns in MDA-MB-231 cells and its mammary fat pad tumor (TMD-231), lung-metastasis (LMD-231), bone-metastasis (BMD-231), adrenal-metastasis (ADMD-231) and brain-metastasis (231-BR) variants. When gene expression between metastases was compared, 231-BR cells showed the highest gene expression difference followed by ADMD-231, LMD-231, and BMD-231 cells. Neuronal transmembrane proteins SLITRK2, TMEM47, and LYPD1 were specifically overexpressed in 231-BR cells. Pathway-analyses revealed activation of signaling networks that would enable cancer cells to adapt to organs of metastasis such as drug detoxification/oxidative stress response/semaphorin neuronal pathway in 231-BR, Notch/orphan nuclear receptor signals involved in steroidogenesis in ADMD-231, acute phase response in LMD-231, and cytokine/hematopoietic stem cell signaling in BMD-231 cells. Only NF-κB signaling pathway activation was common to all except BMD-231 cells. We confirmed NF-κB activation in 231-BR and in a brain metastatic variant of 4T1 cells (4T1-BR). Dimethylaminoparthenolide inhibited NF-κB activity, LYPD1 expression, and proliferation of 231-BR and 4T1-BR cells. Thus, transcriptome change enabling adaptation to host organs is likely one of the mechanisms associated with organ-specific metastasis and could potentially be targeted therapeutically. PMID:25926557

  2. Brazilian Red Propolis Attenuates Inflammatory Signaling Cascade in LPS-Activated Macrophages

    PubMed Central

    Bueno-Silva, Bruno; Kawamoto, Dione; Ando-Suguimoto, Ellen S.; Alencar, Severino M.; Rosalen, Pedro L.; Mayer, Marcia P. A.

    2015-01-01

    Although previous studies suggested an anti-inflammatory property of Brazilian red propolis (BRP), the mechanisms involved in the anti-inflammatory effects of BRP and its activity on macrophages were still not elucidated. This study aimed to evaluate whether BRP attenuates the inflammatory effect of LPS on macrophages and to investigate its underlying mechanisms. BRP was added to RAW 264.7 murine macrophages after activation with LPS. NO production, cell viability, cytokines profile were evaluated. Activation of inflammatory signaling pathways and macrophage polarization were determined by RT-qPCR and Western blot. BRP at 50 μg/ml inhibited NO production by 78% without affecting cell viability. Cd80 and Cd86 were upregulated whereas mrc1 was down regulated by BRP indicating macrophage polarization at M1. BRP attenuated the production of pro-inflammatory mediators IL-12, GM-CSF, IFN-Ɣ, IL-1β in cell supernatants although levels of TNF- α and IL-6 were slightly increased after BRP treatment. Levels of IL-4, IL-10 and TGF-β were also reduced by BRP. BRP significantly reduced the up-regulation promoted by LPS of transcription of genes in inflammatory signaling (Pdk1, Pak1, Nfkb1, Mtcp1, Gsk3b, Fos and Elk1) and of Il1β and Il1f9 (fold-change rate > 5), which were further confirmed by the inhibition of NF-κB and MAPK signaling pathways. Furthermore, the upstream adaptor MyD88 adaptor-like (Mal), also known as TIRAP, involved in TLR2 and TLR4 signaling, was down- regulated in BRP treated LPS-activated macrophages. Given that BRP inhibited multiple signaling pathways in macrophages involved in the inflammatory process activated by LPS, our data indicated that BRP is a noteworthy food-source for the discovery of new bioactive compounds and a potential candidate to attenuate exhacerbated inflammatory diseases. PMID:26660901

  3. Accumulated source imaging of brain activity with both low and high-frequency neuromagnetic signals

    PubMed Central

    Xiang, Jing; Luo, Qian; Kotecha, Rupesh; Korman, Abraham; Zhang, Fawen; Luo, Huan; Fujiwara, Hisako; Hemasilpin, Nat; Rose, Douglas F.

    2014-01-01

    Recent studies have revealed the importance of high-frequency brain signals (>70 Hz). One challenge of high-frequency signal analysis is that the size of time-frequency representation of high-frequency brain signals could be larger than 1 terabytes (TB), which is beyond the upper limits of a typical computer workstation's memory (<196 GB). The aim of the present study is to develop a new method to provide greater sensitivity in detecting high-frequency magnetoencephalography (MEG) signals in a single automated and versatile interface, rather than the more traditional, time-intensive visual inspection methods, which may take up to several days. To address the aim, we developed a new method, accumulated source imaging, defined as the volumetric summation of source activity over a period of time. This method analyzes signals in both low- (1~70 Hz) and high-frequency (70~200 Hz) ranges at source levels. To extract meaningful information from MEG signals at sensor space, the signals were decomposed to channel-cross-channel matrix (CxC) representing the spatiotemporal patterns of every possible sensor-pair. A new algorithm was developed and tested by calculating the optimal CxC and source location-orientation weights for volumetric source imaging, thereby minimizing multi-source interference and reducing computational cost. The new method was implemented in C/C++ and tested with MEG data recorded from clinical epilepsy patients. The results of experimental data demonstrated that accumulated source imaging could effectively summarize and visualize MEG recordings within 12.7 h by using approximately 10 GB of computer memory. In contrast to the conventional method of visually identifying multi-frequency epileptic activities that traditionally took 2–3 days and used 1–2 TB storage, the new approach can quantify epileptic abnormalities in both low- and high-frequency ranges at source levels, using much less time and computer memory. PMID:24904402

  4. Correlations between the signal complexity of cerebral and cardiac electrical activity: a multiscale entropy analysis.

    PubMed

    Lin, Pei-Feng; Lo, Men-Tzung; Tsao, Jenho; Chang, Yi-Chung; Lin, Chen; Ho, Yi-Lwun

    2014-01-01

    The heart begins to beat before the brain is formed. Whether conventional hierarchical central commands sent by the brain to the heart alone explain all the interplay between these two organs should be reconsidered. Here, we demonstrate correlations between the signal complexity of brain and cardiac activity. Eighty-seven geriatric outpatients with healthy hearts and varied cognitive abilities each provided a 24-hour electrocardiography (ECG) and a 19-channel eye-closed routine electroencephalography (EEG). Multiscale entropy (MSE) analysis was applied to three epochs (resting-awake state, photic stimulation of fast frequencies (fast-PS), and photic stimulation of slow frequencies (slow-PS)) of EEG in the 1-58 Hz frequency range, and three RR interval (RRI) time series (awake-state, sleep and that concomitant with the EEG) for each subject. The low-to-high frequency power (LF/HF) ratio of RRI was calculated to represent sympatho-vagal balance. With statistics after Bonferroni corrections, we found that: (a) the summed MSE value on coarse scales of the awake RRI (scales 11-20, RRI-MSE-coarse) were inversely correlated with the summed MSE value on coarse scales of the resting-awake EEG (scales 6-20, EEG-MSE-coarse) at Fp2, C4, T6 and T4; (b) the awake RRI-MSE-coarse was inversely correlated with the fast-PS EEG-MSE-coarse at O1, O2 and C4; (c) the sleep RRI-MSE-coarse was inversely correlated with the slow-PS EEG-MSE-coarse at Fp2; (d) the RRI-MSE-coarse and LF/HF ratio of the awake RRI were correlated positively to each other; (e) the EEG-MSE-coarse at F8 was proportional to the cognitive test score; (f) the results conform to the cholinergic hypothesis which states that cognitive impairment causes reduction in vagal cardiac modulation; (g) fast-PS significantly lowered the EEG-MSE-coarse globally. Whether these heart-brain correlations could be fully explained by the central autonomic network is unknown and needs further exploration. PMID:24498375

  5. Correlations between the Signal Complexity of Cerebral and Cardiac Electrical Activity: A Multiscale Entropy Analysis

    PubMed Central

    Lin, Pei-Feng; Lo, Men-Tzung; Tsao, Jenho; Chang, Yi-Chung; Lin, Chen; Ho, Yi-Lwun

    2014-01-01

    The heart begins to beat before the brain is formed. Whether conventional hierarchical central commands sent by the brain to the heart alone explain all the interplay between these two organs should be reconsidered. Here, we demonstrate correlations between the signal complexity of brain and cardiac activity. Eighty-seven geriatric outpatients with healthy hearts and varied cognitive abilities each provided a 24-hour electrocardiography (ECG) and a 19-channel eye-closed routine electroencephalography (EEG). Multiscale entropy (MSE) analysis was applied to three epochs (resting-awake state, photic stimulation of fast frequencies (fast-PS), and photic stimulation of slow frequencies (slow-PS)) of EEG in the 1–58 Hz frequency range, and three RR interval (RRI) time series (awake-state, sleep and that concomitant with the EEG) for each subject. The low-to-high frequency power (LF/HF) ratio of RRI was calculated to represent sympatho-vagal balance. With statistics after Bonferroni corrections, we found that: (a) the summed MSE value on coarse scales of the awake RRI (scales 11–20, RRI-MSE-coarse) were inversely correlated with the summed MSE value on coarse scales of the resting-awake EEG (scales 6–20, EEG-MSE-coarse) at Fp2, C4, T6 and T4; (b) the awake RRI-MSE-coarse was inversely correlated with the fast-PS EEG-MSE-coarse at O1, O2 and C4; (c) the sleep RRI-MSE-coarse was inversely correlated with the slow-PS EEG-MSE-coarse at Fp2; (d) the RRI-MSE-coarse and LF/HF ratio of the awake RRI were correlated positively to each other; (e) the EEG-MSE-coarse at F8 was proportional to the cognitive test score; (f) the results conform to the cholinergic hypothesis which states that cognitive impairment causes reduction in vagal cardiac modulation; (g) fast-PS significantly lowered the EEG-MSE-coarse globally. Whether these heart-brain correlations could be fully explained by the central autonomic network is unknown and needs further exploration. PMID:24498375

  6. Selenium Deficiency Attenuates Chicken Duodenal Mucosal Immunity via Activation of the NF-κb Signaling Pathway.

    PubMed

    Liu, Zhe; Qu, Yanpeng; Wang, Jianfa; Wu, Rui

    2016-08-01

    Selenium (Se) deficiency can cause intestinal mucosal inflammation, which is related to activation of nuclear transcription factor kappa-B (NF-κB) signaling pathway. However, the mechanism of inflammatory response in chicken duodenal mucosa caused by Se deficiency and its relationship with the NF-κB signaling pathway remain elusive. In this study, we firstly obtained Se-deficient chickens bred with 0.01 mg/kg Se and the normal chickens bred with 0.4 mg/kg Se for 35 days. Then, NF-κB signaling pathway, secretory immunoglobulin A (SIgA), inflammatory cytokines, oxidized glutathione, glutathione peroxidase, and glutathione activities were determined. The results showed that Se deficiency obviously enhanced p50, p65, and p65 DNA-binding activities. The phosphorylation of IκB-α and phosphorylation of kappa-B kinase subunit alpha (IKKα) and IKKα were elevated, but IκB-α was decreased (P < 0.05). Moreover, Se deficiency reduced SIgA amount in the duodenal mucosa but increased the level of interleukin-1β (IL-1β), IL-17A, tumor necrosis factor-α (TNF-α), and interferon gamma (IFN-γ). In contrast, anti-inflammatory cytokines, such as TGF-β1 and IL-10, were significantly suppressed. Additionally, Se deficiency increased oxidized glutathione activity, whereas decreased glutathione peroxidase and glutathione activities (P < 0.05), suggesting that Se deficiency affected the regulation function of redox. Taken together, our results demonstrated that Se deficiency attenuated chicken duodenal mucosal immunity via activation of NF-κB signaling pathway regulated by redox activity, which suggested that Se is a crucial host factor involved in regulating inflammation. PMID:26728795

  7. Convergence of dopamine and glutamate signaling onto striatal ERK activation in response to drugs of abuse

    PubMed Central

    Cahill, Emma; Salery, Marine; Vanhoutte, Peter; Caboche, Jocelyne

    2014-01-01

    Despite their distinct targets, all addictive drugs commonly abused by humans evoke increases in dopamine (DA) concentration within the striatum. The main DA Guanine nucleotide binding protein couple receptors (GPCRs) expressed by medium-sized spiny neurons of the striatum are the D1R and D2R, which are positively and negatively coupled to cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) signaling, respectively. These two DA GPCRs are largely segregated into distinct neuronal populations, where they are co-expressed with glutamate receptors in dendritic spines. Direct and indirect interactions between DA GPCRs and glutamate receptors are the molecular basis by which DA modulates glutamate transmission and controls striatal plasticity and behavior induced by drugs of abuse. A major downstream target of striatal D1R is the extracellular signal-regulated kinase (ERK) kinase pathway. ERK activation by drugs of abuse behaves as a key integrator of D1R and glutamate NMDAR signaling. Once activated, ERK can trigger chromatin remodeling and induce gene expression that permits long-term cellular alterations and drug-induced morphological and behavioral changes. Besides the classical cAMP/PKA pathway, downstream of D1R, recent evidence implicates a cAMP-independent crosstalk mechanism by which the D1R potentiates NMDAR-mediated calcium influx and ERK activation. The mounting evidence of reciprocal modulation of DA and glutamate receptors adds further intricacy to striatal synaptic signaling and is liable to prove relevant for addictive drug-induced signaling, plasticity, and behavior. Herein, we review the evidence that built our understanding of the consequences of this synergistic signaling for the actions of drugs of abuse. PMID:24409148

  8. Epigenetic Activation of Wnt/β-Catenin Signaling in NAFLD-Associated Hepatocarcinogenesis.

    PubMed

    Tian, Yuan; Mok, Myth T S; Yang, Pengyuan; Cheng, Alfred S L

    2016-01-01

    Non-alcoholic fatty liver disease (NAFLD), characterized by fat accumulation in liver, is closely associated with central obesity, over-nutrition and other features of metabolic syndrome, which elevate the risk of developing hepatocellular carcinoma (HCC). The Wnt/β-catenin signaling pathway plays a significant role in the physiology and pathology of liver. Up to half of HCC patients have activation of Wnt/β-catenin signaling. However, the mutation frequencies of CTNNB1 (encoding β-catenin protein) or other antagonists targeting Wnt/β-catenin signaling are low in HCC patients, suggesting that genetic mutations are not the major factor driving abnormal β-catenin activities in HCC. Emerging evidence has demonstrated that obesity-induced metabolic pathways can deregulate chromatin modifiers such as histone deacetylase 8 to trigger undesired global epigenetic changes, thereby modifying gene expression program which contributes to oncogenic signaling. This review focuses on the aberrant epigenetic activation of Wnt/β-catenin in the development of NAFLD-associated HCC. A deeper understanding of the molecular mechanisms underlying such deregulation may shed light on the identification of novel druggable epigenetic targets for the prevention and/or treatment of HCC in obese and diabetic patients. PMID:27556491

  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. PMID:27581482

  10. Redundant canonical and noncanonical Caenorhabditis elegans p21-activated kinase signaling governs distal tip cell migrations.

    PubMed

    Peters, Eldon C; Gossett, Andrea J; Goldstein, Bob; Der, Channing J; Reiner, David J

    2013-02-01

    p21-activated kinases (Paks) are prominent mediators of Rac/Cdc42-dependent and -independent signaling and regulate signal transduction and cytoskeletal-based cell movements. We used the reproducible migrations of the Caenorhabditis elegans gonadal distal tip cells to show that two of the three nematode Pak proteins, MAX-2 and PAK-1, function redundantly in regulation of cell migration but are regulated by very different mechanisms. First, we suggest that MAX-2 requires CED-10/Rac function and thus functions canonically. Second, PIX-1 and GIT-1 function in the same role as PAK-1, and PAK-1 interaction with PIX-1 is required for PAK-1 activity; thus, PAK-1 functions noncanonically. The human Pak-Pix-Git complex is central to noncanonical Pak signaling and requires only modest Rac/CDC-42 input. Unlike the human complex, our results suggest that the C. elegans Pak-Pix-Git complex requires PAK-1 kinase domain activity. This study delineates signaling network relationships in this cell migration model, thus providing potential further mechanistic insights and an assessment of total Pak contribution to cell migration events. PMID:23390595

  11. F-actin polymerization and retrograde flow drive sustained PLCγ1 signaling during T cell activation

    PubMed Central

    Babich, Alexander; Li, Shuixing; O'Connor, Roddy S.; Milone, Michael C.; Freedman, Bruce D.

    2012-01-01

    Activation of T cells by antigen-presenting cells involves assembly of signaling molecules into dynamic microclusters (MCs) within a specialized membrane domain termed the immunological synapse (IS). Actin and myosin IIA localize to the IS, and depletion of F-actin abrogates MC movement and T cell activation. However, the mechanisms that coordinate actomyosin dynamics and T cell receptor signaling are poorly understood. Using pharmacological inhibitors that perturb individual aspects of actomyosin dynamics without disassembling the network, we demonstrate that F-actin polymerization is the primary driver of actin retrograde flow, whereas myosin IIA promotes long-term integrity of the IS. Disruption of F-actin retrograde flow, but not myosin IIA contraction, arrested MC centralization and inhibited sustained Ca2+ signaling at the level of endoplasmic reticulum store release. Furthermore, perturbation of retrograde flow inhibited PLCγ1 phosphorylation within MCs but left Zap70 activity intact. These studies highlight the importance of ongoing actin polymerization as a central driver of actomyosin retrograde flow, MC centralization, and sustained Ca2+ signaling. PMID:22665519

  12. 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

  13. Periostin Responds to Mechanical Stress and Tension by Activating the MTOR Signaling Pathway

    PubMed Central

    Rosselli-Murai, Luciana K.; Galindo-Moreno, Pablo; Padial-Molina, Miguel; Volk, Sarah L.; Murai, Marcelo J.; Rios, Hector F.; Squarize, Cristiane H.; Castilho, Rogerio M.

    2013-01-01

    Current knowledge about Periostin biology has expanded from its recognized functions in embryogenesis and bone metabolism to its roles in tissue repair and remodeling and its clinical implications in cancer. Emerging evidence suggests that Periostin plays a critical role in the mechanism of wound healing; however, the paracrine effect of Periostin in epithelial cell biology is still poorly understood. We found that epithelial cells are capable of producing endogenous Periostin that, unlike mesenchymal cell, cannot be secreted. Epithelial cells responded to Periostin paracrine stimuli by enhancing cellular migration and proliferation and by activating the mTOR signaling pathway. Interestingly, biomechanical stimulation of epithelial cells, which simulates tension forces that occur during initial steps of tissue healing, induced Periostin production and mTOR activation. The molecular association of Periostin and mTOR signaling was further dissected by administering rapamycin, a selective pharmacological inhibitor of mTOR, and by disruption of Raptor and Rictor scaffold proteins implicated in the regulation of mTORC1 and mTORC2 complex assembly. Both strategies resulted in ablation of Periostin-induced mitogenic and migratory activity. These results indicate that Periostin-induced epithelial migration and proliferation requires mTOR signaling. Collectively, our findings identify Periostin as a mechanical stress responsive molecule that is primarily secreted by fibroblasts during wound healing and expressed endogenously in epithelial cells resulting in the control of cellular physiology through a mechanism mediated by the mTOR signaling cascade. PMID:24349533

  14. Analysis of G Protein and β-Arrestin Activation in Chemokine Receptors Signaling.

    PubMed

    Vacchini, Alessandro; Busnelli, Marta; Chini, Bice; Locati, Massimo; Borroni, Elena Monica

    2016-01-01

    Chemokines are key regulators of leukocyte migration and play fundamental roles in immune responses. The chemokine system includes a set of over 40 ligands which engage in a promiscuous fashion a panel of over 25 receptors belonging to a distinct family of 7 transmembrane-domain receptors (7TM) widely expressed on a variety of cells. Although responses evoked by chemokine receptors have long been considered the result of balanced activation of the G protein- and β-arrestin-dependent signaling modules, evidence is accumulating showing that these receptors are capable, as other 7TMs, to activate different signaling modules in a ligand- and cell/tissue-specific manner. This biased signaling, or functional selectivity, confers a hitherto largely uncharacterized level of complexity to the chemokine system and challenges our present understanding of its redundancy. At the same time, it also provides new insights of relevance for chemokine receptors targeting drug development plans. Here, we provide current methods to study biased signaling of chemokine receptors by dissecting G proteins and β-arrestins activation upon chemokine stimulation. PMID:26921957

  15. Epigenetic Activation of Wnt/β-Catenin Signaling in NAFLD-Associated Hepatocarcinogenesis

    PubMed Central

    Tian, Yuan; Mok, Myth T.S.; Yang, Pengyuan; Cheng, Alfred S.L.

    2016-01-01

    Non-alcoholic fatty liver disease (NAFLD), characterized by fat accumulation in liver, is closely associated with central obesity, over-nutrition and other features of metabolic syndrome, which elevate the risk of developing hepatocellular carcinoma (HCC). The Wnt/β-catenin signaling pathway plays a significant role in the physiology and pathology of liver. Up to half of HCC patients have activation of Wnt/β-catenin signaling. However, the mutation frequencies of CTNNB1 (encoding β-catenin protein) or other antagonists targeting Wnt/β-catenin signaling are low in HCC patients, suggesting that genetic mutations are not the major factor driving abnormal β-catenin activities in HCC. Emerging evidence has demonstrated that obesity-induced metabolic pathways can deregulate chromatin modifiers such as histone deacetylase 8 to trigger undesired global epigenetic changes, thereby modifying gene expression program which contributes to oncogenic signaling. This review focuses on the aberrant epigenetic activation of Wnt/β-catenin in the development of NAFLD-associated HCC. A deeper understanding of the molecular mechanisms underlying such deregulation may shed light on the identification of novel druggable epigenetic targets for the prevention and/or treatment of HCC in obese and diabetic patients. PMID:27556491

  16. Regulation of Glucose Tolerance and Sympathetic Activity by MC4R Signaling in the Lateral Hypothalamus

    PubMed Central

    Morgan, Donald A.; McDaniel, Latisha N.; Yin, Terry; Khan, Michael; Jiang, Jingwei; Acevedo, Michael R.; Walsh, Susan A.; Ponto, Laura L. Boles; Norris, Andrew W.; Lutter, Michael; Rahmouni, Kamal

    2015-01-01

    Melanocortin 4 receptor (MC4R) signaling mediates diverse physiological functions, including energy balance, glucose homeostasis, and autonomic activity. Although the lateral hypothalamic area (LHA) is known to express MC4Rs and to receive input from leptin-responsive arcuate proopiomelanocortin neurons, the physiological functions of MC4Rs in the LHA are incompletely understood. We report that MC4RLHA signaling regulates glucose tolerance and sympathetic nerve activity. Restoring expression of MC4Rs specifically in the LHA improves glucose intolerance in obese MC4R-null mice without affecting body weight or circulating insulin levels. Fluorodeoxyglucose-mediated tracing of whole-body glucose uptake identifies the interscapular brown adipose tissue (iBAT) as a primary source where glucose uptake is increased in MC4RLHA mice. Direct multifiber sympathetic nerve recording further reveals that sympathetic traffic to iBAT is significantly increased in MC4RLHA mice, which accompanies a significant elevation of Glut4 expression in iBAT. Finally, bilateral iBAT denervation prevents the glucoregulatory effect of MC4RLHA signaling. These results identify a novel role for MC4RLHA signaling in the control of sympathetic nerve activity and glucose tolerance independent of energy balance. PMID:25605803

  17. Human Macrophage SCN5A Activates an Innate Immune Signaling Pathway for Antiviral Host Defense*

    PubMed Central

    Jones, Alexis; Kainz, Danielle; Khan, Faatima; Lee, Cara; Carrithers, Michael D.

    2014-01-01

    Pattern recognition receptors contain a binding domain for pathogen-associated molecular patterns coupled to a signaling domain that regulates transcription of host immune response genes. Here, a novel mechanism that links pathogen recognition to channel activation and downstream signaling is proposed. We demonstrate that an intracellular sodium channel variant, human macrophage SCN5A, initiates signaling and transcription through a calcium-dependent isoform of adenylate cyclase, ADCY8, and the transcription factor, ATF2. Pharmacological stimulation with a channel agonist or treatment with cytoplasmic poly(I:C), a mimic of viral dsRNA, activates this pathway to regulate expression of SP100-related genes and interferon β. Electrophysiological analysis reveals that the SCN5A variant mediates nonselective outward currents and a small, but detectable, inward current. Intracellular poly(I:C) markedly augments an inward voltage-sensitive sodium current and inhibits the outward nonselective current. These results suggest human macrophage SCN5A initiates signaling in an innate immune pathway relevant to antiviral host defense. It is postulated that SCN5A is a novel pathogen sensor and that this pathway represents a channel activation-dependent mechanism of transcriptional regulation. PMID:25368329

  18. Abrogating monoacylglycerol acyltransferase activity in liver improves glucose tolerance and hepatic insulin signaling in obese mice.

    PubMed

    Hall, Angela M; Soufi, Nisreen; Chambers, Kari T; Chen, Zhouji; Schweitzer, George G; McCommis, Kyle S; Erion, Derek M; Graham, Mark J; Su, Xiong; Finck, Brian N

    2014-07-01

    Monoacylglycerol acyltransferase (MGAT) enzymes convert monoacylglycerol to diacylglycerol (DAG), a lipid that has been linked to the development of hepatic insulin resistance through activation of protein kinase C (PKC). The expression of genes that encode MGAT enzymes is induced in the livers of insulin-resistant human subjects with nonalcoholic fatty liver disease, but whether MGAT activation is causal of hepatic steatosis or insulin resistance is unknown. We show that the expression of Mogat1, which encodes MGAT1, and MGAT activity are also increased in diet-induced obese (DIO) and ob/obmice. To probe the metabolic effects of MGAT1 in the livers of obese mice, we administered antisense oligonucleotides (ASOs) against Mogat1 to DIO and ob/ob mice for 3 weeks. Knockdown of Mogat1 in liver, which reduced hepatic MGAT activity, did not affect hepatic triacylglycerol content and unexpectedly increased total DAG content. Mogat1 inhibition also increased both membrane and cytosolic compartment DAG levels. However, Mogat1 ASO treatment significantly improved glucose tolerance and hepatic insulin signaling in obese mice. In summary, inactivation of hepatic MGAT activity, which is markedly increased in obese mice, improved glucose tolerance and hepatic insulin signaling independent of changes in body weight, intrahepatic DAG and TAG content, and PKC signaling. PMID:24595352

  19. Escin activates AKT-Nrf2 signaling to protect retinal pigment epithelium cells from oxidative stress.

    PubMed

    Wang, Kaijun; Jiang, Yiqian; Wang, Wei; Ma, Jian; Chen, Min

    2015-12-25

    Here we explored the anti-oxidative and cytoprotective potentials of escin, a natural triterpene-saponin, against hydrogen peroxide (H2O2) in retinal pigment epithelium (RPE) cells. We showed that escin remarkably attenuated H2O2-induced death and apoptosis of established (ARPE-19) and primary murine RPE cells. Meanwhile, ROS production and lipid peroxidation by H2O2 were remarkably inhibited by escin. Escin treatment in RPE cells resulted in NF-E2-related factor 2 (Nrf2) signaling activation, evidenced by transcription of anti-oxidant-responsive element (ARE)-regulated genes, including HO-1, NQO-1 and SRXN-1. Knockdown of Nrf2 through targeted shRNAs/siRNAs alleviated escin-mediated ARE gene transcription, and almost abolished escin-mediated anti-oxidant activity and RPE cytoprotection against H2O2. Reversely, escin was more potent against H2O2 damages in Nrf2-over-expressed ARPE-19 cells. Further studies showed that escin-induced Nrf2 activation in RPE cells required AKT signaling. AKT inhibitors (LY294002 and perifosine) blocked escin-induced AKT activation, and dramatically inhibited Nrf2 phosphorylation, its cytosol accumulation and nuclear translocation in RPE cells. Escin-induced RPE cytoprotection against H2O2 was also alleviated by the AKT inhibitors. Together, these results demonstrate that escin protects RPE cells from oxidative stress possibly through activating AKT-Nrf2 signaling. PMID:26505797

  20. Canonical transient receptor potential channels promote cardiomyocyte hypertrophy through activation of calcineurin signaling.

    PubMed

    Bush, Erik W; Hood, David B; Papst, Philip J; Chapo, Joseph A; Minobe, Wayne; Bristow, Michael R; Olson, Eric N; McKinsey, Timothy A

    2006-11-01

    The calcium/calmodulin-dependent phosphatase calcineurin plays a central role in the control of cardiomyocyte hypertrophy in response to pathological stimuli. Although calcineurin is present at high levels in normal heart, its activity appears to be unaffected by calcium during the course of a cardiac cycle. The mechanism(s) whereby calcineurin is selectively activated by calcium under pathological conditions has remained unclear. Here, we demonstrate that diverse signals for cardiac hypertrophy stimulate expression of canonical transient receptor potential (TRPC) channels. TRPC consists of a family of seven membrane-spanning nonselective cation channels that have been implicated in the nonvoltage-gated influx of calcium in response to G protein-coupled receptor signaling, receptor tyrosine kinase signaling, and depletion of internal calcium stores. TRPC3 expression is up-regulated in multiple rodent models of pathological cardiac hypertrophy, whereas TRPC5 expression is induced in failing human heart. We demonstrate that TRPC promotes cardiomyocyte hypertrophy through activation of calcineurin and its downstream effector, the nuclear factor of activated T cells transcription factor. These results define a novel role for TRPC channels in the control of cardiac growth, and suggest that a TRPC-derived pool of calcium contributes to selective activation of calcineurin in diseased heart. PMID:16950785

  1. MALT1-Ubiquitination Triggers Non-Genomic NF-κB/IKK Signaling upon Platelet Activation

    PubMed Central

    Karim, Zubair A.; Vemana, Hari Priya; Khasawneh, Fadi T.

    2015-01-01

    We have recently shown that IKK complex plays an important non-genomic role in platelet function, i.e., regulates SNARE machinery-dependent membrane fusion. In this connection, it is well known that MALT1, whose activity is modulated by proteasome, plays an important role in the regulation of IKK complex. Therefore, the present studies investigated the mechanism by which IKK signaling is regulated in the context of the platelet proteasome. It was found that platelets express a functional proteasome, and form CARMA/MALT1/Bcl10 (CBM) complex when activated. Using a pharmacological inhibitor, the proteasome was found to regulate platelet function (aggregation, integrin activation, secretion, phosphatidylserine exposure and changes in intracellular calcium). It was also found to regulate thrombogenesis and physiologic hemostasis. We also observed, upon platelet activation, that MALT1 is ubiquitinated, and this coincides with the activation of the IKK/NF-κB-signaling pathway. Finally, we observed that the proteasome inhibitor blocks CBM complex formation and the interaction of IKKγ and MALT1; abrogates SNARE formation, and the association of MALT1 with TAK1 and TAB2, which are upstream of the CBM complex. Thus, our data demonstrate that MALT1 ubiquitination is critical for the engagement of CBM and IKK complexes, thereby directing platelet signals to the NF-κB pathway. PMID:25748427

  2. Stress-activated signaling responses leading to apoptosis following photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Oleinick, Nancy L.; He, Jin; Xue, Liang-yan; Separovic, Duska

    1998-05-01

    Photodynamic treatment with the phthalocyanine Pc 4, a mitochondrially localizing photosensitizer, is an efficient inducer of cell death by apoptosis, a cell suicide pathway that can be triggered by physiological stimuli as well as by various types of cellular damage. Upon exposure of the dye- loaded cells to red light, several stress signalling pathways are rapidly activated. In murine L5178Y-R lymphoblasts, caspase activation and other hallmarks of the final phase of apoptosis are observed within a few minutes post-PDT. In Chinese hamster CHO-K1 cells, the first signs of