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Sample records for signal regulating map

  1. Selective regulation of MAP kinase signaling by an endomembrane phosphatidylinositol 4-kinase.

    PubMed

    Cappell, Steven D; Dohlman, Henrik G

    2011-04-29

    Multiple MAP kinase pathways share components yet initiate distinct biological processes. Signaling fidelity can be maintained by scaffold proteins and restriction of signaling complexes to discreet subcellular locations. For example, the yeast MAP kinase scaffold Ste5 binds to phospholipids produced at the plasma membrane and promotes selective MAP kinase activation. Here we show that Pik1, a phosphatidylinositol 4-kinase that localizes primarily to the Golgi, also regulates MAP kinase specificity but does so independently of Ste5. Pik1 is required for full activation of the MAP kinases Fus3 and Hog1 and represses activation of Kss1. Further, we show by genetic epistasis analysis that Pik1 likely regulates Ste11 and Ste50, components shared by all three MAP kinase pathways, through their interaction with the scaffold protein Opy2. These findings reveal a new regulator of signaling specificity functioning at endomembranes rather than at the plasma membrane. PMID:21388955

  2. MAP1S Protein Regulates the Phagocytosis of Bacteria and Toll-like Receptor (TLR) Signaling.

    PubMed

    Shi, Ming; Zhang, Yifan; Liu, Leyuan; Zhang, Tingting; Han, Fang; Cleveland, Joseph; Wang, Fen; McKeehan, Wallace L; Li, Yu; Zhang, Dekai

    2016-01-15

    Phagocytosis is a critical cellular process for innate immune defense against microbial infection. The regulation of phagocytosis process is complex and has not been well defined. An intracellular molecule might regulate cell surface-initiated phagocytosis, but the underlying molecular mechanism is poorly understood (1). In this study, we found that microtubule-associated protein 1S (MAP1S), a protein identified recently that is involved in autophagy (2), is expressed primarily in macrophages. MAP1S-deficient macrophages are impaired in the phagocytosis of bacteria. Furthermore, we demonstrate that MAP1S interacts directly with MyD88, a key adaptor of Toll-like receptors (TLRs), upon TLR activation and affects the TLR signaling pathway. Intriguingly, we also observe that, upon TLR activation, MyD88 participates in autophagy processing in a MAP1S-dependent manner by co-localizing with MAP1 light chain 3 (MAP1-LC3 or LC3). Therefore, we reveal that an intracellular autophagy-related molecule of MAP1S controls bacterial phagocytosis through TLR signaling.

  3. RKIP regulates MAP kinase signaling in cells with defective B-Raf activity.

    PubMed

    Zeng, Lingchun; Ehrenreiter, Karin; Menon, Jyotsana; Menard, Ray; Kern, Florian; Nakazawa, Yoko; Bevilacqua, Elena; Imamoto, Akira; Baccarini, Manuela; Rosner, Marsha Rich

    2013-05-01

    MAP kinase (MAPK) signaling results from activation of Raf kinases in response to external or internal stimuli. Here, we demonstrate that Raf kinase inhibitory protein (RKIP) regulates the activation of MAPK when B-Raf signaling is defective. We used multiple models including mouse embryonic fibroblasts (MEFs) and primary keratinocytes from RKIP- or Raf-deficient mice as well as allografts in mice to investigate the mechanism. Loss of B-Raf protein or activity significantly reduces MAPK activation in these cells. We show that RKIP depletion can rescue the compromised ERK activation and promote proliferation, and this rescue occurs through a Raf-1 dependent mechanism. These results provide formal evidence that RKIP is a bona fide regulator of Raf-1. We propose a new model in which RKIP plays a key role in regulating the ability of cells to signal through Raf-1 to ERK in B-Raf compromised cells.

  4. Mapping and signaling of neural pathways involved in the regulation of hydromineral homeostasis

    PubMed Central

    Antunes-Rodrigues, J.; Ruginsk, S.G.; Mecawi, A.S.; Margatho, L.O.; Cruz, J.C.; Vilhena-Franco, T.; Reis, W.L.; Ventura, R.R.; Reis, L.C.; Vivas, L.M.; Elias, L.L.K.

    2013-01-01

    Several forebrain and brainstem neurochemical circuitries interact with peripheral neural and humoral signals to collaboratively maintain both the volume and osmolality of extracellular fluids. Although much progress has been made over the past decades in the understanding of complex mechanisms underlying neuroendocrine control of hydromineral homeostasis, several issues still remain to be clarified. The use of techniques such as molecular biology, neuronal tracing, electrophysiology, immunohistochemistry, and microinfusions has significantly improved our ability to identify neuronal phenotypes and their signals, including those related to neuron-glia interactions. Accordingly, neurons have been shown to produce and release a large number of chemical mediators (neurotransmitters, neurohormones and neuromodulators) into the interstitial space, which include not only classic neurotransmitters, such as acetylcholine, amines (noradrenaline, serotonin) and amino acids (glutamate, GABA), but also gaseous (nitric oxide, carbon monoxide and hydrogen sulfide) and lipid-derived (endocannabinoids) mediators. This efferent response, initiated within the neuronal environment, recruits several peripheral effectors, such as hormones (glucocorticoids, angiotensin II, estrogen), which in turn modulate central nervous system responsiveness to systemic challenges. Therefore, in this review, we shall evaluate in an integrated manner the physiological control of body fluid homeostasis from the molecular aspects to the systemic and integrated responses. PMID:23579631

  5. Mapping and signaling of neural pathways involved in the regulation of hydromineral homeostasis.

    PubMed

    Antunes-Rodrigues, J; Ruginsk, S G; Mecawi, A S; Margatho, L O; Cruz, J C; Vilhena-Franco, T; Reis, W L; Ventura, R R; Reis, L C; Vivas, L M; Elias, L L K

    2013-04-01

    Several forebrain and brainstem neurochemical circuitries interact with peripheral neural and humoral signals to collaboratively maintain both the volume and osmolality of extracellular fluids. Although much progress has been made over the past decades in the understanding of complex mechanisms underlying neuroendocrine control of hydromineral homeostasis, several issues still remain to be clarified. The use of techniques such as molecular biology, neuronal tracing, electrophysiology, immunohistochemistry, and microinfusions has significantly improved our ability to identify neuronal phenotypes and their signals, including those related to neuron-glia interactions. Accordingly, neurons have been shown to produce and release a large number of chemical mediators (neurotransmitters, neurohormones and neuromodulators) into the interstitial space, which include not only classic neurotransmitters, such as acetylcholine, amines (noradrenaline, serotonin) and amino acids (glutamate, GABA), but also gaseous (nitric oxide, carbon monoxide and hydrogen sulfide) and lipid-derived (endocannabinoids) mediators. This efferent response, initiated within the neuronal environment, recruits several peripheral effectors, such as hormones (glucocorticoids, angiotensin II, estrogen), which in turn modulate central nervous system responsiveness to systemic challenges. Therefore, in this review, we shall evaluate in an integrated manner the physiological control of body fluid homeostasis from the molecular aspects to the systemic and integrated responses. PMID:23579631

  6. Regulation of endothelial protein C receptor shedding by cytokines is mediated through differential activation of MAP kinase signaling pathways

    SciTech Connect

    Menschikowski, Mario; Hagelgans, Albert; Eisenhofer, Graeme; Siegert, Gabriele

    2009-09-10

    The endothelial protein C receptor (EPCR) plays a pivotal role in coagulation, inflammation, cell proliferation, and cancer, but its activity is markedly changed by ectodomain cleavage and release as the soluble protein (sEPCR). In this study we examined the mechanisms involved in the regulation of EPCR shedding in human umbilical endothelial cells (HUVEC). Interleukin-1{beta} (IL-1{beta}) and tumor necrosis factor-{alpha} (TNF-{alpha}), but not interferon-{gamma} and interleukin-6, suppressed EPCR mRNA transcription and cell-associated EPCR expression in HUVEC. The release of sEPCR induced by IL-1{beta} and TNF-{alpha} correlated with activation of p38 MAPK and c-Jun N-terminal kinase (JNK). EPCR shedding was also induced by phorbol 12-myristate 13-acetate, ionomycin, anisomycin, thiol oxidants or alkylators, thrombin, and disruptors of lipid rafts. Both basal and induced shedding of EPCR was blocked by the metalloproteinase inhibitors, TAPI-0 and GM6001, and by the reduced non-protein thiols, glutathione, dihydrolipoic acid, dithiothreitol, and N-acetyl-L-cysteine. Because other antioxidants and scavengers of reactive oxygen species failed to block the cleavage of EPCR, a direct suppression of metalloproteinase activity seems responsible for the observed effects of reduced thiols. In summary, the shedding of EPCR in HUVEC is effectively regulated by IL-1{beta} and TNF-{alpha}, and downstream by MAP kinase signaling pathways and metalloproteinases.

  7. miR-625-3p regulates oxaliplatin resistance by targeting MAP2K6-p38 signalling in human colorectal adenocarcinoma cells.

    PubMed

    Rasmussen, Mads Heilskov; Lyskjær, Iben; Jersie-Christensen, Rosa Rakownikow; Tarpgaard, Line Schmidt; Primdal-Bengtson, Bjarke; Nielsen, Morten Muhlig; Pedersen, Jakob Skou; Hansen, Tine Plato; Hansen, Flemming; Olsen, Jesper Velgaard; Pfeiffer, Per; Ørntoft, Torben Falck; Andersen, Claus Lindbjerg

    2016-01-01

    Oxaliplatin resistance in colorectal cancers (CRC) is a major medical problem, and predictive markers are urgently needed. Recently, miR-625-3p was reported as a promising predictive marker. Herein, we show that miR-625-3p functionally induces oxaliplatin resistance in CRC cells, and identify the signalling networks affected by miR-625-3p. We show that the p38 MAPK activator MAP2K6 is a direct target of miR-625-3p, and, accordingly, is downregulated in non-responder patients of oxaliplatin therapy. miR-625-3p-mediated resistance is reversed by anti-miR-625-3p treatment and ectopic expression of a miR-625-3p insensitive MAP2K6 variant. In addition, reduction of p38 signalling by using siRNAs, chemical inhibitors or expression of a dominant-negative MAP2K6 protein induces resistance to oxaliplatin. Transcriptome, proteome and phosphoproteome profiles confirm inactivation of MAP2K6-p38 signalling as one likely mechanism of oxaliplatin resistance. Our study shows that miR-625-3p induces oxaliplatin resistance by abrogating MAP2K6-p38-regulated apoptosis and cell cycle control networks, and corroborates the predictive power of miR-625-3p. PMID:27526785

  8. miR-625-3p regulates oxaliplatin resistance by targeting MAP2K6-p38 signalling in human colorectal adenocarcinoma cells

    PubMed Central

    Rasmussen, Mads Heilskov; Lyskjær, Iben; Jersie-Christensen, Rosa Rakownikow; Tarpgaard, Line Schmidt; Primdal-Bengtson, Bjarke; Nielsen, Morten Muhlig; Pedersen, Jakob Skou; Hansen, Tine Plato; Hansen, Flemming; Olsen, Jesper Velgaard; Pfeiffer, Per; Ørntoft, Torben Falck; Andersen, Claus Lindbjerg

    2016-01-01

    Oxaliplatin resistance in colorectal cancers (CRC) is a major medical problem, and predictive markers are urgently needed. Recently, miR-625-3p was reported as a promising predictive marker. Herein, we show that miR-625-3p functionally induces oxaliplatin resistance in CRC cells, and identify the signalling networks affected by miR-625-3p. We show that the p38 MAPK activator MAP2K6 is a direct target of miR-625-3p, and, accordingly, is downregulated in non-responder patients of oxaliplatin therapy. miR-625-3p-mediated resistance is reversed by anti-miR-625-3p treatment and ectopic expression of a miR-625-3p insensitive MAP2K6 variant. In addition, reduction of p38 signalling by using siRNAs, chemical inhibitors or expression of a dominant-negative MAP2K6 protein induces resistance to oxaliplatin. Transcriptome, proteome and phosphoproteome profiles confirm inactivation of MAP2K6-p38 signalling as one likely mechanism of oxaliplatin resistance. Our study shows that miR-625-3p induces oxaliplatin resistance by abrogating MAP2K6-p38-regulated apoptosis and cell cycle control networks, and corroborates the predictive power of miR-625-3p. PMID:27526785

  9. Nitric Oxide Affects ERK Signaling through Down-Regulation of MAP Kinase Phosphatase Levels during Larval Development of the Ascidian Ciona intestinalis

    PubMed Central

    Palumbo, Anna

    2014-01-01

    In the ascidian Ciona intestinalis larval development and metamorphosis require a complex interplay of events, including nitric oxide (NO) production, MAP kinases (ERK, JNK) and caspase-3 activation. We have previously shown that NO levels affect the rate of metamorphosis, regulate caspase activity and promote an oxidative stress pathway, resulting in protein nitration. Here, we report that NO down-regulates MAP kinase phosphatases (mkps) expression affecting positively ERK signaling. By pharmacological approach, we observed that the reduction of endogenous NO levels caused a decrease of ERK phosphorylation, whereas increasing levels of NO induced ERK activation. We have also identified the ERK gene network affected by NO, including mpk1, mpk3 and some key developmental genes by quantitative gene expression analysis. We demonstrate that NO induces an ERK-independent down-regulation of mkp1 and mkp3, responsible for maintaining the ERK phosphorylation levels necessary for transcription of key metamorphic genes, such as the hormone receptor rev-erb and the van willebrand protein vwa1c. These results add new insights into the role played by NO during larval development and metamorphosis in Ciona, highlighting the cross-talk between different signaling pathways. PMID:25058405

  10. DLK-1/p38 MAP Kinase Signaling Controls Cilium Length by Regulating RAB-5 Mediated Endocytosis in Caenorhabditis elegans.

    PubMed

    van der Vaart, Aniek; Rademakers, Suzanne; Jansen, Gert

    2015-12-01

    Cilia are sensory organelles present on almost all vertebrate cells. Cilium length is constant, but varies between cell types, indicating that cilium length is regulated. How this is achieved is unclear, but protein transport in cilia (intraflagellar transport, IFT) plays an important role. Several studies indicate that cilium length and function can be modulated by environmental cues. As a model, we study a C. elegans mutant that carries a dominant active G protein α subunit (gpa-3QL), resulting in altered IFT and short cilia. In a screen for suppressors of the gpa-3QL short cilium phenotype, we identified uev-3, which encodes an E2 ubiquitin-conjugating enzyme variant that acts in a MAP kinase pathway. Mutation of two other components of this pathway, dual leucine zipper-bearing MAPKKK DLK-1 and p38 MAPK PMK-3, also suppress the gpa-3QL short cilium phenotype. However, this suppression seems not to be caused by changes in IFT. The DLK-1/p38 pathway regulates several processes, including microtubule stability and endocytosis. We found that reducing endocytosis by mutating rabx-5 or rme-6, RAB-5 GEFs, or the clathrin heavy chain, suppresses gpa-3QL. In addition, gpa-3QL animals showed reduced levels of two GFP-tagged proteins involved in endocytosis, RAB-5 and DPY-23, whereas pmk-3 mutant animals showed accumulation of GFP-tagged RAB-5. Together our results reveal a new role for the DLK-1/p38 MAPK pathway in control of cilium length by regulating RAB-5 mediated endocytosis.

  11. DLK-1/p38 MAP Kinase Signaling Controls Cilium Length by Regulating RAB-5 Mediated Endocytosis in Caenorhabditis elegans

    PubMed Central

    van der Vaart, Aniek; Rademakers, Suzanne; Jansen, Gert

    2015-01-01

    Cilia are sensory organelles present on almost all vertebrate cells. Cilium length is constant, but varies between cell types, indicating that cilium length is regulated. How this is achieved is unclear, but protein transport in cilia (intraflagellar transport, IFT) plays an important role. Several studies indicate that cilium length and function can be modulated by environmental cues. As a model, we study a C. elegans mutant that carries a dominant active G protein α subunit (gpa-3QL), resulting in altered IFT and short cilia. In a screen for suppressors of the gpa-3QL short cilium phenotype, we identified uev-3, which encodes an E2 ubiquitin-conjugating enzyme variant that acts in a MAP kinase pathway. Mutation of two other components of this pathway, dual leucine zipper-bearing MAPKKK DLK-1 and p38 MAPK PMK-3, also suppress the gpa-3QL short cilium phenotype. However, this suppression seems not to be caused by changes in IFT. The DLK-1/p38 pathway regulates several processes, including microtubule stability and endocytosis. We found that reducing endocytosis by mutating rabx-5 or rme-6, RAB-5 GEFs, or the clathrin heavy chain, suppresses gpa-3QL. In addition, gpa-3QL animals showed reduced levels of two GFP-tagged proteins involved in endocytosis, RAB-5 and DPY-23, whereas pmk-3 mutant animals showed accumulation of GFP-tagged RAB-5. Together our results reveal a new role for the DLK-1/p38 MAPK pathway in control of cilium length by regulating RAB-5 mediated endocytosis. PMID:26657059

  12. Chloroplast retrograde signal regulates flowering.

    PubMed

    Feng, Peiqiang; Guo, Hailong; Chi, Wei; Chai, Xin; Sun, Xuwu; Xu, Xiumei; Ma, Jinfang; Rochaix, Jean-David; Leister, Dario; Wang, Haiyang; Lu, Congming; Zhang, Lixin

    2016-09-20

    Light is a major environmental factor regulating flowering time, thus ensuring reproductive success of higher plants. In contrast to our detailed understanding of light quality and photoperiod mechanisms involved, the molecular basis underlying high light-promoted flowering remains elusive. Here we show that, in Arabidopsis, a chloroplast-derived signal is critical for high light-regulated flowering mediated by the FLOWERING LOCUS C (FLC). We also demonstrate that PTM, a PHD transcription factor involved in chloroplast retrograde signaling, perceives such a signal and mediates transcriptional repression of FLC through recruitment of FVE, a component of the histone deacetylase complex. Thus, our data suggest that chloroplasts function as essential sensors of high light to regulate flowering and adaptive responses by triggering nuclear transcriptional changes at the chromatin level. PMID:27601637

  13. MAP3K19 Is a Novel Regulator of TGF-β Signaling That Impacts Bleomycin-Induced Lung Injury and Pulmonary Fibrosis

    PubMed Central

    Franz-Bacon, Karin; DiTirro, Danielle N.; Ly, Tai Wei; Bacon, Kevin B.

    2016-01-01

    Idiopathic pulmonary fibrosis (IPF) is a progressive, debilitating disease for which two medications, pirfenidone and nintedanib, have only recently been approved for treatment. The cytokine TGF-β has been shown to be a central mediator in the disease process. We investigated the role of a novel kinase, MAP3K19, upregulated in IPF tissue, in TGF-β-induced signal transduction and in bleomycin-induced pulmonary fibrosis. MAP3K19 has a very limited tissue expression, restricted primarily to the lungs and trachea. In pulmonary tissue, expression was predominantly localized to alveolar and interstitial macrophages, bronchial epithelial cells and type II pneumocytes of the epithelium. MAP3K19 was also found to be overexpressed in bronchoalveolar lavage macrophages from IPF patients compared to normal patients. Treatment of A549 or THP-1 cells with either MAP3K19 siRNA or a highly potent and specific inhibitor reduced phospho-Smad2 & 3 nuclear translocation following TGF-β stimulation. TGF-β-induced gene transcription was also strongly inhibited by both the MAP3K19 inhibitor and nintedanib, whereas pirfenidone had a much less pronounced effect. In combination, the MAP3K19 inhibitor appeared to act synergistically with either pirfenidone or nintedanib, at the level of target gene transcription or protein production. Finally, in an animal model of IPF, inhibition of MAP3K19 strongly attenuated bleomycin-induced pulmonary fibrosis when administered either prophylactically ortherapeutically. In summary, these results strongly suggest that inhibition of MAP3K19 may have a beneficial therapeutic effect in the treatment of IPF and represents a novel strategy to target this disease. PMID:27144281

  14. PfIRR Interacts with HrIGF-I and Activates the MAP-kinase and PI3-kinase Signaling Pathways to Regulate Glycogen Metabolism in Pinctada fucata

    PubMed Central

    Shi, Yu; He, Mao-xian

    2016-01-01

    The insulin-induced mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways are major intracellular signaling modules and conserved among eukaryotes that are known to regulate diverse cellular processes. However, they have not been investigated in the mollusk species Pinctada fucata. Here, we demonstrate that insulin-related peptide receptor of P. fucata (pfIRR) interacts with human recombinant insulin-like growth factor I (hrIGF-I), and stimulates the MAPK and PI3K signaling pathways in P. fucata oocytes. We also show that inhibition of pfIRR by the inhibitor PQ401 significantly attenuates the basal and hrIGF-I-induced phosphorylation of MAPK and PI3K/Akt at amino acid residues threonine 308 and serine 473. Furthermore, our experiments show that there is cross-talk between the MAPK and PI3K/Akt pathways, in which MAPK kinase positively regulates the PI3K pathway, and PI3K positively regulates the MAPK cascade. Intramuscular injection of hrIGF-I stimulates the PI3K and MAPK pathways to increase the expression of pfirr, protein phosphatase 1, glucokinase, and the phosphorylation of glycogen synthase, decreases the mRNA expression of glycogen synthase kinase-3 beta, decreases glucose levels in hemocytes, and increases glycogen levels in digestive glands. These results suggest that the MAPK and PI3K pathways in P. fucata transmit the hrIGF-I signal to regulate glycogen metabolism. PMID:26911653

  15. PfIRR Interacts with HrIGF-I and Activates the MAP-kinase and PI3-kinase Signaling Pathways to Regulate Glycogen Metabolism in Pinctada fucata.

    PubMed

    Shi, Yu; He, Mao-xian

    2016-01-01

    The insulin-induced mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) pathways are major intracellular signaling modules and conserved among eukaryotes that are known to regulate diverse cellular processes. However, they have not been investigated in the mollusk species Pinctada fucata. Here, we demonstrate that insulin-related peptide receptor of P. fucata (pfIRR) interacts with human recombinant insulin-like growth factor I (hrIGF-I), and stimulates the MAPK and PI3K signaling pathways in P. fucata oocytes. We also show that inhibition of pfIRR by the inhibitor PQ401 significantly attenuates the basal and hrIGF-I-induced phosphorylation of MAPK and PI3K/Akt at amino acid residues threonine 308 and serine 473. Furthermore, our experiments show that there is cross-talk between the MAPK and PI3K/Akt pathways, in which MAPK kinase positively regulates the PI3K pathway, and PI3K positively regulates the MAPK cascade. Intramuscular injection of hrIGF-I stimulates the PI3K and MAPK pathways to increase the expression of pfirr, protein phosphatase 1, glucokinase, and the phosphorylation of glycogen synthase, decreases the mRNA expression of glycogen synthase kinase-3 beta, decreases glucose levels in hemocytes, and increases glycogen levels in digestive glands. These results suggest that the MAPK and PI3K pathways in P. fucata transmit the hrIGF-I signal to regulate glycogen metabolism.

  16. CD28 signal transduction pathways. A comparison of B7-1 and B7-2 regulation of the map kinases: ERK2 and Jun kinases.

    PubMed

    Nunes, J A; Battifora, M; Woodgett, J R; Truneh, A; Olive, D; Cantrell, D A

    1996-01-01

    The present study compares the mitogen-activated protein (MAP) kinase responses in T cells activated with the CD28 ligands B7-1 (CD80) and B7-2/B70 (CD86). Ligands B7-1 and B7-2 do not activate the Raf-1/ERK2 cascade, but share the ability to activate related Jun kinases. These natural ligands for CD28 had no stimulatory effect alone on Jun kinase activation, but the data show that B7-1 and B7-2 could both co-operate with intracellular Ca2+ increase and protein kinase C (PKC) activation to stimulate Jun kinases. The present study shows that the interaction of CD28 with its ligands B7-1 and B7-2 can induce identical signal transduction through the MAP kinase cascades.

  17. Phosphodiesterase MoPdeH targets MoMck1 of the conserved mitogen-activated protein (MAP) kinase signalling pathway to regulate cell wall integrity in rice blast fungus Magnaporthe oryzae.

    PubMed

    Yin, Ziyi; Tang, Wei; Wang, Jingzhen; Liu, Xinyu; Yang, Lina; Gao, Chuyun; Zhang, Jinlong; Zhang, Haifeng; Zheng, Xiaobo; Wang, Ping; Zhang, Zhengguang

    2016-06-01

    In the rice blast fungus Magnaporthe oryzae, the high-affinity cyclic adenosine monophosphate (cAMP) phosphodiesterase MoPdeH is important not only for cAMP signalling and pathogenicity, but also for cell wall integrity (CWI) maintenance through an unknown mechanism. By utilizing affinity purification, we found that MoPdeH interacts with MoMck1, one of the components of the mitogen-activated protein (MAP) kinase cascade that regulates CWI. Overexpression of MoMCK1 suppressed defects in autolysis and pathogenicity of the ΔMopdeH mutant, although partially, suggesting that MoPdeH plays a critical role in CWI maintenance mediated by the MAP kinase pathway. We found that MoMck1 and two other MAP kinase cascade components, MoMkk1 and MoMps1, modulate intracellular cAMP levels by regulating the expression of MoPDEH through a feedback loop. In addition, disruption of MoMKK1 resulted in less aerial hyphal formation, defective asexual development and attenuated pathogenicity. Moreover, MoMkk1 plays a role in the response to osmotic stress via regulation of MoOsm1 phosphorylation levels, whereas endoplasmic reticulum (ER) stress enhances MoMps1 phosphorylation and loss of the MAP kinase cascade component affects the unfolded protein response (UPR) pathway. Taken together, our findings demonstrate that MoPdeH functions upstream of the MoMck1-MoMkk1-MoMps1 MAP kinase pathway to regulate CWI, and that MoPdeH also mediates crosstalk between the cAMP signalling pathway, the osmotic sensing high osmolarity glycerol (HOG) pathway and the dithiothreitol (DTT)-induced UPR pathway in M. oryzae.

  18. Phosphodiesterase MoPdeH targets MoMck1 of the conserved mitogen-activated protein (MAP) kinase signalling pathway to regulate cell wall integrity in rice blast fungus Magnaporthe oryzae.

    PubMed

    Yin, Ziyi; Tang, Wei; Wang, Jingzhen; Liu, Xinyu; Yang, Lina; Gao, Chuyun; Zhang, Jinlong; Zhang, Haifeng; Zheng, Xiaobo; Wang, Ping; Zhang, Zhengguang

    2016-06-01

    In the rice blast fungus Magnaporthe oryzae, the high-affinity cyclic adenosine monophosphate (cAMP) phosphodiesterase MoPdeH is important not only for cAMP signalling and pathogenicity, but also for cell wall integrity (CWI) maintenance through an unknown mechanism. By utilizing affinity purification, we found that MoPdeH interacts with MoMck1, one of the components of the mitogen-activated protein (MAP) kinase cascade that regulates CWI. Overexpression of MoMCK1 suppressed defects in autolysis and pathogenicity of the ΔMopdeH mutant, although partially, suggesting that MoPdeH plays a critical role in CWI maintenance mediated by the MAP kinase pathway. We found that MoMck1 and two other MAP kinase cascade components, MoMkk1 and MoMps1, modulate intracellular cAMP levels by regulating the expression of MoPDEH through a feedback loop. In addition, disruption of MoMKK1 resulted in less aerial hyphal formation, defective asexual development and attenuated pathogenicity. Moreover, MoMkk1 plays a role in the response to osmotic stress via regulation of MoOsm1 phosphorylation levels, whereas endoplasmic reticulum (ER) stress enhances MoMps1 phosphorylation and loss of the MAP kinase cascade component affects the unfolded protein response (UPR) pathway. Taken together, our findings demonstrate that MoPdeH functions upstream of the MoMck1-MoMkk1-MoMps1 MAP kinase pathway to regulate CWI, and that MoPdeH also mediates crosstalk between the cAMP signalling pathway, the osmotic sensing high osmolarity glycerol (HOG) pathway and the dithiothreitol (DTT)-induced UPR pathway in M. oryzae. PMID:27193947

  19. Cyanidin-3-glucoside inhibits UVB-induced oxidative damage and inflammation by regulating MAP kinase and NF-κB signaling pathways in SKH-1 hairless mice skin

    SciTech Connect

    Pratheeshkumar, Poyil; Son, Young-Ok; Wang, Xin; Divya, Sasidharan Padmaja; Joseph, Binoy; Hitron, John Andrew; Wang, Lei; Kim, Donghern; Yin, Yuanqin; Roy, Ram Vinod; Lu, Jian; Zhang, Zhuo; Wang, Yitao; and others

    2014-10-01

    Skin cancer is one of the most commonly diagnosed cancers in the United States. Exposure to ultraviolet-B (UVB) radiation induces inflammation and photocarcinogenesis in mammalian skin. Cyanidin-3-glucoside (C3G), a member of the anthocyanin family, is present in various vegetables and fruits especially in edible berries, and displays potent antioxidant and anticarcinogenic properties. In this study, we have assessed the in vivo effects of C3G on UVB irradiation induced chronic inflammatory responses in SKH-1 hairless mice, a well-established model for UVB-induced skin carcinogenesis. Here, we show that C3G inhibited UVB-induced skin damage and inflammation in SKH-1 hairless mice. Our results indicate that C3G inhibited glutathione depletion, lipid peroxidation and myeloperoxidation in mouse skin by chronic UVB exposure. C3G significantly decreased the production of UVB-induced pro-inflammatory cytokines, such as IL-6 and TNF-α, associated with cutaneous inflammation. Likewise, UVB-induced inflammatory responses were diminished by C3G as observed by a remarkable reduction in the levels of phosphorylated MAP kinases, Erk1/2, p38, JNK1/2 and MKK4. Furthermore, C3G also decreased UVB-induced cyclooxygenase-2 (COX-2), PGE{sub 2} and iNOS levels, which are well-known key mediators of inflammation and cancer. Treatment with C3G inhibited UVB-induced nuclear translocation of NF-κB and degradation of IκBα in mice skin. Immunofluorescence assay revealed that topical application of C3G inhibited the expression of 8-hydroxy-2′-deoxyguanosine, proliferating cell nuclear antigen, and cyclin D1 in chronic UVB exposed mouse skin. Collectively, these data indicates that C3G can provide substantial protection against the adverse effects of UVB radiation by modulating UVB-induced MAP kinase and NF-κB signaling pathways. - Highlights: • C3G inhibited UVB-induced oxidative damage and inflammation. • C3G inhibited UVB-induced COX-2, iNOS and PGE{sub 2} production. • C3G

  20. Map4k4 suppresses Srebp-1 and adipocyte lipogenesis independent of JNK signaling[S

    PubMed Central

    Danai, Laura V.; Guilherme, Adilson; Guntur, Kalyani V.; Straubhaar, Juerg; Nicoloro, Sarah M.; Czech, Michael P.

    2013-01-01

    Adipose tissue lipogenesis is paradoxically impaired in human obesity, promoting ectopic triglyceride (TG) deposition, lipotoxicity, and insulin resistance. We previously identified mitogen-activated protein kinase kinase kinase kinase 4 (Map4k4), a sterile 20 protein kinase reported to be upstream of c-Jun NH2-terminal kinase (JNK) signaling, as a novel negative regulator of insulin-stimulated glucose transport in adipocytes. Using full-genome microarray analysis we uncovered a novel role for Map4k4 as a suppressor of lipid synthesis. We further report here the surprising finding that Map4k4 suppresses adipocyte lipogenesis independently of JNK. Thus, while Map4k4 silencing in adipocytes enhances the expression of lipogenic enzymes, concomitant with increased conversion of 14C-glucose and 14C-acetate into TGs and fatty acids, JNK1 and JNK2 depletion causes the opposite effects. Furthermore, high expression of Map4k4 fails to activate endogenous JNK, while Map4k4 depletion does not attenuate JNK activation by tumor necrosis factor α. Map4k4 silencing in cultured adipocytes elevates both the total protein expression and cleavage of sterol-regulated element binding protein-1 (Srebp-1) in a rapamycin-sensitive manner, consistent with Map4k4 signaling via mechanistic target of rapamycin complex 1 (mTORC1). We show Map4k4 depletion requires Srebp-1 upregulation to increase lipogenesis and further show that Map4k4 promotes AMP-protein kinase (AMPK) signaling and the phosphorylation of mTORC1 binding partner raptor (Ser792) to inhibit mTORC1. Our results indicate that Map4k4 inhibits adipose lipogenesis by suppression of Srebp-1 in an AMPK- and mTOR-dependent but JNK-independent mechanism. PMID:23924694

  1. Fibroblast growth factor 23 regulates renal 1,25-dihydroxyvitamin D and phosphate metabolism via the MAP kinase signaling pathway in Hyp mice.

    PubMed

    Ranch, Daniel; Zhang, Martin Yh; Portale, Anthony A; Perwad, Farzana

    2011-08-01

    In X-linked hypophosphatemia (XLH) and in its murine homologue, the Hyp mouse, increased circulating concentrations of fibroblast growth factor 23 (FGF-23) are critical to the pathogenesis of disordered metabolism of phosphate (P(i)) and 1,25-dihydroxyvitamin D [1,25(OH)(2)D]. In this study, we hypothesized that in Hyp mice, FGF-23-mediated suppression of renal 1,25(OH)(2)D production and P(i) reabsorption depends on activation of mitogen-activated protein kinase (MAPK) signaling. Wild-type and Hyp mice were administered either vehicle or the MEK inhibitor PD0325901 (12.5 mg/kg) orally daily for 4 days. At baseline, the renal abundance of early growth response 1 (egr1) mRNA was approximately 2-fold greater in Hyp mice than in wild-type mice. Treatment with PD0325901 greatly suppressed egr1 mRNA abundance in both wild-type and Hyp mice. In Hyp mice, PD0325901 induced an 8-fold increase in renal 1α-hydroxylase mRNA expression and a 4-fold increase in serum 1,25(OH)(2)D concentrations compared with vehicle-treated Hyp mice. Serum P(i) levels in Hyp mice increased significantly after treatment with PD0325901, and the increase was associated with increased renal Npt2a mRNA abundance and brush-border membrane Npt2a protein expression. These findings provide evidence that in Hyp mice, MAPK signaling is constitutively activated in the kidney and support the hypothesis that the FGF-23-mediated suppression of renal 1,25(OH)(2)D production and P(i) reabsorption depends on activation of MAPK signaling via MEK/ERK1/2. These findings demonstrate the physiologic importance of MAPK signaling in the actions of FGF-23 in regulating renal 1,25(OH)(2)D and P(i) metabolism.

  2. Fibroblast Growth Factor 23 Regulates Renal 1,25-Dihydroxyvitamin D and Phosphate Metabolism via the MAP Kinase Signaling Pathway in Hyp Mice

    PubMed Central

    Ranch, Daniel; Zhang, Martin YH; Portale, Anthony A; Perwad, Farzana

    2015-01-01

    In X-linked hypophosphatemia (XLH) and in its murine homologue, the Hyp mouse, increased circulating concentrations of fibroblast growth factor 23 (FGF-23) are critical to the pathogenesis of disordered metabolism of phosphate (Pi) and 1,25-dihydroxyvitamin D [1,25(OH)2D]. In this study, we hypothesized that in Hyp mice, FGF-23-mediated suppression of renal 1,25(OH)2D production and Pi reabsorption depends on activation of mitogen-activated protein kinase (MAPK) signaling. Wild-type and Hyp mice were administered either vehicle or the MEK inhibitor PD0325901 (12.5 mg/kg) orally daily for 4 days. At baseline, the renal abundance of early growth response 1 (egr1) mRNA was approximately 2-fold greater in Hyp mice than in wild-type mice. Treatment with PD0325901 greatly suppressed egr1 mRNA abundance in both wild-type and Hyp mice. In Hyp mice, PD0325901 induced an 8-fold increase in renal 1α-hydroxylase mRNA expression and a 4-fold increase in serum 1,25(OH)2D concentrations compared with vehicle-treated Hyp mice. Serum Pi levels in Hyp mice increased significantly after treatment with PD0325901, and the increase was associated with increased renal Npt2a mRNA abundance and brush-border membrane Npt2a protein expression. These findings provide evidence that in Hyp mice, MAPK signaling is constitutively activated in the kidney and support the hypothesis that the FGF-23-mediated suppression of renal 1,25(OH)2D production and Pi reabsorption depends on activation of MAPK signaling via MEK/ERK1/2. These findings demonstrate the physiologic importance of MAPK signaling in the actions of FGF-23 in regulating renal 1,25(OH)2D and Pi metabolism. PMID:21472778

  3. Understanding splicing regulation through RNA splicing maps.

    PubMed

    Witten, Joshua T; Ule, Jernej

    2011-03-01

    Alternative splicing is a highly regulated process that greatly increases the proteome diversity and plays an important role in cellular differentiation and disease. Interactions between RNA-binding proteins (RBPs) and pre-mRNA are the principle regulator of splicing decisions. Findings from recent genome-wide studies of protein-RNA interactions have been combined with assays of the global effects of RBPs on splicing to create RNA splicing maps. These maps integrate information from all pre-mRNAs regulated by single RBPs to identify the global positioning principles guiding splicing regulation. Recent studies using this approach have identified a set of positional principles that are shared between diverse RBPs. Here, we discuss how insights from RNA splicing maps of different RBPs inform the mechanistic models of splicing regulation.

  4. MAPPING GASOLINE REQUIREMENTS, APPLICABLE REGULATIONS AND BANS

    EPA Science Inventory

    Federal and State regulations play an important role in understanding gasoline composition around the United States. Multiple sources of information on these programs were used to develop reliable, up-to-date maps showing gasoline requirements imposed by various regulations. Th...

  5. Endocannabinoid Signaling Regulates Sleep Stability

    PubMed Central

    Pava, Matthew J.; Makriyannis, Alexandros; Lovinger, David M.

    2016-01-01

    The hypnogenic properties of cannabis have been recognized for centuries, but endogenous cannabinoid (endocannabinoid) regulation of vigilance states is poorly characterized. We report findings from a series of experiments in mice measuring sleep with polysomnography after various systemic pharmacological manipulations of the endocannabinoid system. Rapid, unbiased scoring of vigilance states was achieved using an automated algorithm that we devised and validated. Increasing endocannabinoid tone with a selective inhibitor of monoacyglycerol lipase (JZL184) or fatty acid amide hydrolase (AM3506) produced a transient increase in non-rapid eye movement (NREM) sleep due to an augmentation of the length of NREM bouts (NREM stability). Similarly, direct activation of type 1 cannabinoid (CB1) receptors with CP47,497 increased NREM stability, but both CP47,497 and JZL184 had a secondary effect that reduced NREM sleep time and stability. This secondary response to these drugs was similar to the early effect of CB1 blockade with the antagonist/inverse agonist AM281, which fragmented NREM sleep. The magnitude of the effects produced by JZL184 and AM281 were dependent on the time of day this drug was administered. While activation of CB1 resulted in only a slight reduction in gamma power, CB1 blockade had dramatic effects on broadband power in the EEG, particularly at low frequencies. However, CB1 blockade did not significantly reduce the rebound in NREM sleep following total sleep deprivation. These results support the hypothesis that endocannabinoid signaling through CB1 is necessary for NREM stability but it is not necessary for sleep homeostasis. PMID:27031992

  6. Endocannabinoid Signaling Regulates Sleep Stability.

    PubMed

    Pava, Matthew J; Makriyannis, Alexandros; Lovinger, David M

    2016-01-01

    The hypnogenic properties of cannabis have been recognized for centuries, but endogenous cannabinoid (endocannabinoid) regulation of vigilance states is poorly characterized. We report findings from a series of experiments in mice measuring sleep with polysomnography after various systemic pharmacological manipulations of the endocannabinoid system. Rapid, unbiased scoring of vigilance states was achieved using an automated algorithm that we devised and validated. Increasing endocannabinoid tone with a selective inhibitor of monoacyglycerol lipase (JZL184) or fatty acid amide hydrolase (AM3506) produced a transient increase in non-rapid eye movement (NREM) sleep due to an augmentation of the length of NREM bouts (NREM stability). Similarly, direct activation of type 1 cannabinoid (CB1) receptors with CP47,497 increased NREM stability, but both CP47,497 and JZL184 had a secondary effect that reduced NREM sleep time and stability. This secondary response to these drugs was similar to the early effect of CB1 blockade with the antagonist/inverse agonist AM281, which fragmented NREM sleep. The magnitude of the effects produced by JZL184 and AM281 were dependent on the time of day this drug was administered. While activation of CB1 resulted in only a slight reduction in gamma power, CB1 blockade had dramatic effects on broadband power in the EEG, particularly at low frequencies. However, CB1 blockade did not significantly reduce the rebound in NREM sleep following total sleep deprivation. These results support the hypothesis that endocannabinoid signaling through CB1 is necessary for NREM stability but it is not necessary for sleep homeostasis. PMID:27031992

  7. Endocannabinoid Signaling Regulates Sleep Stability.

    PubMed

    Pava, Matthew J; Makriyannis, Alexandros; Lovinger, David M

    2016-01-01

    The hypnogenic properties of cannabis have been recognized for centuries, but endogenous cannabinoid (endocannabinoid) regulation of vigilance states is poorly characterized. We report findings from a series of experiments in mice measuring sleep with polysomnography after various systemic pharmacological manipulations of the endocannabinoid system. Rapid, unbiased scoring of vigilance states was achieved using an automated algorithm that we devised and validated. Increasing endocannabinoid tone with a selective inhibitor of monoacyglycerol lipase (JZL184) or fatty acid amide hydrolase (AM3506) produced a transient increase in non-rapid eye movement (NREM) sleep due to an augmentation of the length of NREM bouts (NREM stability). Similarly, direct activation of type 1 cannabinoid (CB1) receptors with CP47,497 increased NREM stability, but both CP47,497 and JZL184 had a secondary effect that reduced NREM sleep time and stability. This secondary response to these drugs was similar to the early effect of CB1 blockade with the antagonist/inverse agonist AM281, which fragmented NREM sleep. The magnitude of the effects produced by JZL184 and AM281 were dependent on the time of day this drug was administered. While activation of CB1 resulted in only a slight reduction in gamma power, CB1 blockade had dramatic effects on broadband power in the EEG, particularly at low frequencies. However, CB1 blockade did not significantly reduce the rebound in NREM sleep following total sleep deprivation. These results support the hypothesis that endocannabinoid signaling through CB1 is necessary for NREM stability but it is not necessary for sleep homeostasis.

  8. Regulation of Hippo signalling by p38 signalling.

    PubMed

    Huang, Dashun; Li, Xiaojiao; Sun, Li; Huang, Ping; Ying, Hao; Wang, Hui; Wu, Jiarui; Song, Haiyun

    2016-08-01

    The Hippo signalling pathway has a crucial role in growth control during development, and its dysregulation contributes to tumorigenesis. Recent studies uncover multiple upstream regulatory inputs into Hippo signalling, which affects phosphorylation of the transcriptional coactivator Yki/YAP/TAZ by Wts/Lats. Here we identify the p38 mitogen-activated protein kinase (MAPK) pathway as a new upstream branch of the Hippo pathway. In Drosophila, overexpression of MAPKK gene licorne (lic), or MAPKKK gene Mekk1, promotes Yki activity and induces Hippo target gene expression. Loss-of-function studies show that lic regulates Hippo signalling in ovary follicle cells and in the wing disc. Epistasis analysis indicates that Mekk1 and lic affect Hippo signalling via p38b and wts We further demonstrate that the Mekk1-Lic-p38b cascade inhibits Hippo signalling by promoting F-actin accumulation and Jub phosphorylation. In addition, p38 signalling modulates actin filaments and Hippo signalling in parallel to small GTPases Ras, Rac1, and Rho1. Lastly, we show that p38 signalling regulates Hippo signalling in mammalian cell lines. The Lic homologue MKK3 promotes nuclear localization of YAP via the actin cytoskeleton. Upregulation or downregulation of the p38 pathway regulates YAP-mediated transcription. Our work thus reveals a conserved crosstalk between the p38 MAPK pathway and the Hippo pathway in growth regulation. PMID:27402810

  9. The NO-cGMP-PKG Signaling Pathway Regulates Synaptic Plasticity and Fear Memory Consolidation in the Lateral Amygdala via Activation of ERK/MAP Kinase

    ERIC Educational Resources Information Center

    Ota, Kristie T.; Pierre, Vicki J.; Ploski, Jonathan E.; Queen, Kaila; Schafe, Glenn E.

    2008-01-01

    Recent studies have shown that nitric oxide (NO) signaling plays a crucial role in memory consolidation of Pavlovian fear conditioning and in synaptic plasticity in the lateral amygdala (LA). In the present experiments, we examined the role of the cGMP-dependent protein kinase (PKG), a downstream effector of NO, in fear memory consolidation and…

  10. Regulation of carbamoyl phosphate synthetase by MAP kinase.

    PubMed

    Graves, L M; Guy, H I; Kozlowski, P; Huang, M; Lazarowski, E; Pope, R M; Collins, M A; Dahlstrand, E N; Earp, H S; Evans, D R

    2000-01-20

    The de novo synthesis of pyrimidine nucleotides is required for mammalian cells to proliferate. The rate-limiting step in this pathway is catalysed by carbamoyl phosphate synthetase (CPS II), part of the multifunctional enzyme CAD. Here we describe the regulation of CAD by the mitogen-activated protein (MAP) kinase cascade. When phosphorylated by MAP kinase in vitro or activated by epidermal growth factor in vivo, CAD lost its feedback inhibition (which is dependent on uridine triphosphate) and became more sensitive to activation (which depends upon phosphoribosyl pyrophosphate). Both these allosteric regulatory changes favour biosynthesis of pyrimidines for growth. They were accompanied by increased epidermal growth factor-dependent phosphorylation of CAD in vivo and were prevented by inhibition of MAP kinase. Mutation of a consensus MAP kinase phosphorylation site abolished the changes in CAD allosteric regulation that were stimulated by growth factors. Finally, consistent with an effect of MAP kinase signalling on CPS II activity, epidermal growth factor increased cellular uridine triphosphate and this increase was reversed by inhibition of MAP kinase. Hence these studies may indicate a direct link between activation of the MAP kinase cascade and de novo biosynthesis of pyrimidine nucleotides. PMID:10659854

  11. Signaling Network Map of Endothelial TEK Tyrosine Kinase.

    PubMed

    Khan, Aafaque Ahmad; Sandhya, Varot K; Singh, Priyata; Parthasarathy, Deepak; Kumar, Awinav; Advani, Jayshree; Gattu, Rudrappa; Ranjit, Dhanya V; Vaidyanathan, Rama; Mathur, Premendu Prakash; Prasad, T S Keshava; Mac Gabhann, F; Pandey, Akhilesh; Raju, Rajesh; Gowda, Harsha

    2014-01-01

    TEK tyrosine kinase is primarily expressed on endothelial cells and is most commonly referred to as TIE2. TIE2 is a receptor tyrosine kinase modulated by its ligands, angiopoietins, to regulate the development and remodeling of vascular system. It is also one of the critical pathways associated with tumor angiogenesis and familial venous malformations. Apart from the vascular system, TIE2 signaling is also associated with postnatal hematopoiesis. Despite the involvement of TIE2-angiopoietin system in several diseases, the downstream molecular events of TIE2-angiopoietin signaling are not reported in any pathway repository. Therefore, carrying out a detailed review of published literature, we have documented molecular signaling events mediated by TIE2 in response to angiopoietins and developed a network map of TIE2 signaling. The pathway information is freely available to the scientific community through NetPath, a manually curated resource of signaling pathways. We hope that this pathway resource will provide an in-depth view of TIE2-angiopoietin signaling and will lead to identification of potential therapeutic targets for TIE2-angiopoietin associated disorders.

  12. Regulation of Drosophila lifespan by JNK signaling

    PubMed Central

    Biteau, Benoit; Karpac, Jason; Hwangbo, DaeSung; Jasper, Heinrich

    2010-01-01

    Cellular responses to extrinsic and intrinsic insults have to be carefully regulated to properly coordinate cytoprotection, repair processes, cell proliferation and apoptosis. Stress signaling pathways, most prominently the Jun-N-terminal Kinase (JNK) pathway, are critical regulators of such cellular responses and have accordingly been implicated in the regulation of lifespan in various organisms. JNK signaling promotes cytoprotective gene expression, but also interacts with the Insulin signaling pathway to influence growth, metabolism, stress tolerance and regeneration. Here, we review recent studies in Drosophila that elucidate the tissue-specific and systemic consequences of JNK activation that ultimately impact lifespan of the organism. PMID:21111799

  13. The NO-cGMP-PKG signaling pathway regulates synaptic plasticity and fear memory consolidation in the lateral amygdala via activation of ERK/MAP kinase.

    PubMed

    Ota, Kristie T; Pierre, Vicki J; Ploski, Jonathan E; Queen, Kaila; Schafe, Glenn E

    2008-10-01

    Recent studies have shown that nitric oxide (NO) signaling plays a crucial role in memory consolidation of Pavlovian fear conditioning and in synaptic plasticity in the lateral amygdala (LA). In the present experiments, we examined the role of the cGMP-dependent protein kinase (PKG), a downstream effector of NO, in fear memory consolidation and long-term potentiation (LTP) at thalamic and cortical input pathways to the LA. In behavioral experiments, rats given intra-LA infusions of either the PKG inhibitor Rp-8-Br-PET-cGMPS or the PKG activator 8-Br-cGMP exhibited dose-dependent impairments or enhancements of fear memory consolidation, respectively. In slice electrophysiology experiments, bath application of Rp-8-Br-PET-cGMPS or the guanylyl cyclase inhibitor LY83583 impaired LTP at thalamic, but not cortical inputs to the LA, while bath application of 8-Br-cGMP or the guanylyl cyclase activator YC-1 resulted in enhanced LTP at thalamic inputs to the LA. Interestingly, YC-1-induced enhancement of LTP in the LA was reversed by concurrent application of the MEK inhibitor U0126, suggesting that the NO-cGMP-PKG signaling pathway may promote synaptic plasticity and fear memory formation in the LA, in part by activating the ERK/MAPK signaling cascade. As a test of this hypothesis, we next showed that rats given intra-LA infusion of the PKG inhibitor Rp-8-Br-PET-cGMPS or the PKG activator 8-Br-cGMP exhibit impaired or enhanced activation, respectively, of ERK/MAPK in the LA after fear conditioning. Collectively, our findings suggest that an NO-cGMP-PKG-dependent form of synaptic plasticity at thalamic input synapses to the LA may underlie memory consolidation of Pavlovian fear conditioning, in part, via activation of the ERK/MAPK signaling cascade.

  14. A network map of Interleukin-10 signaling pathway.

    PubMed

    Verma, Renu; Balakrishnan, Lavanya; Sharma, Kusum; Khan, Aafaque Ahmad; Advani, Jayshree; Gowda, Harsha; Tripathy, Srikanth Prasad; Suar, Mrutyunjay; Pandey, Akhilesh; Gandotra, Sheetal; Prasad, T S Keshava; Shankar, Subramanian

    2016-03-01

    Interleukin-10 (IL-10) is an anti-inflammatory cytokine with important immunoregulatory functions. It is primarily secreted by antigen-presenting cells such as activated T-cells, monocytes, B-cells and macrophages. In biologically functional form, it exists as a homodimer that binds to tetrameric heterodimer IL-10 receptor and induces downstream signaling. IL-10 is associated with survival, proliferation and anti-apoptotic activities of various cancers such as Burkitt lymphoma, non-Hodgkins lymphoma and non-small scell lung cancer. In addition, it plays a central role in survival and persistence of intracellular pathogens such as Leishmania donovani, Mycobacterium tuberculosis and Trypanosoma cruzi inside the host. The signaling mechanisms of IL-10 cytokine are not well explored and a well annotated pathway map has been lacking. To this end, we developed a pathway resource by manually annotating the IL-10 induced signaling molecules derived from literature. The reactions were categorized under molecular associations, activation/inhibition, catalysis, transport and gene regulation. In all, 37 molecules and 76 reactions were annotated. The IL-10 signaling pathway can be freely accessed through NetPath, a resource of signal transduction pathways previously developed by our group. PMID:26253919

  15. How Do Gangliosides Regulate RTKs Signaling?

    PubMed Central

    Julien, Sylvain; Bobowski, Marie; Steenackers, Agata; Le Bourhis, Xuefen; Delannoy, Philippe

    2013-01-01

    Gangliosides, the glycosphingolipids carrying one or several sialic acid residues, are located on the outer leaflet of the plasma membrane in glycolipid-enriched microdomains, where they interact with molecules of signal transduction pathways including receptors tyrosine kinases (RTKs). The role of gangliosides in the regulation of signal transduction has been reported in many cases and in a large number of cell types. In this review, we summarize the current knowledge on the biosynthesis of gangliosides and the mechanism by which they regulate RTKs signaling. PMID:24709879

  16. Master Regulators in Plant Glucose Signaling Networks

    PubMed Central

    Sheen, Jen

    2014-01-01

    The daily life of photosynthetic plants revolves around sugar production, transport, storage and utilization, and the complex sugar metabolic and signaling networks integrate internal regulators and environmental cues to govern and sustain plant growth and survival. Although diverse sugar signals have emerged as pivotal regulators from embryogenesis to senescence, glucose is the most ancient and conserved regulatory signal that controls gene and protein expression, cell-cycle progression, central and secondary metabolism, as well as growth and developmental programs. Glucose signals are perceived and transduced by two principal mechanisms: direct sensing through glucose sensors and indirect sensing via a variety of energy and metabolite sensors. This review focuses on the comparative and functional analyses of three glucose-modulated master regulators in Arabidopsis thaliana, the hexokinase1 (HXK1) glucose sensor, the energy sensor kinases KIN10/KIN11 inactivated by glucose, and the glucose-activated target of rapamycin (TOR) kinase. These regulators are evolutionarily conserved, but have evolved universal and unique regulatory wiring and functions in plants and animals. They form protein complexes with multiple partners as regulators or effectors to serve distinct functions in different subcellular locales and organs, and play integrative and complementary roles from cellular signaling and metabolism to development in the plant glucose signaling networks. PMID:25530701

  17. Signaling mechanisms regulating Wallerian degeneration

    PubMed Central

    Freeman, Marc R.

    2014-01-01

    Summary Wallerian degeneration (WD) occurs after an axon is cut or crushed and entails the disintegration and clearance of the severed axon distal to the injury site. WD was initially thought to result from the passive wasting away of the distal axonal fragment, presumably because it lacked a nutrient supply from the cell body. The discovery of the slow Wallerian degeneration (Wlds) mutant mouse, in which distal severed axons survive intact for weeks rather than only 1–2 days, radically changed our thoughts on the autonomy of axon survival. Wlds taught us that under some conditions the axonal compartment can survive for weeks after axotomy without a cell body. The phenotypic and molecular characterization of Wlds and current models for Wlds molecular function are reviewed herein—the mechanism(s) by which WldS spares severed axons remains unresolved. However, recent studies inspired by Wlds have led to the identification of the first “axon death” signaling molecules whose endogenous activities promote axon destruction during WD. PMID:24907513

  18. Mitochondrial retrograde signaling regulates neuronal function

    PubMed Central

    Cagin, Umut; Duncan, Olivia F.; Gatt, Ariana P.; Dionne, Marc S.; Sweeney, Sean T.; Bateman, Joseph M.

    2015-01-01

    Mitochondria are key regulators of cellular homeostasis, and mitochondrial dysfunction is strongly linked to neurodegenerative diseases, including Alzheimer’s and Parkinson’s. Mitochondria communicate their bioenergetic status to the cell via mitochondrial retrograde signaling. To investigate the role of mitochondrial retrograde signaling in neurons, we induced mitochondrial dysfunction in the Drosophila nervous system. Neuronal mitochondrial dysfunction causes reduced viability, defects in neuronal function, decreased redox potential, and reduced numbers of presynaptic mitochondria and active zones. We find that neuronal mitochondrial dysfunction stimulates a retrograde signaling response that controls the expression of several hundred nuclear genes. We show that the Drosophila hypoxia inducible factor alpha (HIFα) ortholog Similar (Sima) regulates the expression of several of these retrograde genes, suggesting that Sima mediates mitochondrial retrograde signaling. Remarkably, knockdown of Sima restores neuronal function without affecting the primary mitochondrial defect, demonstrating that mitochondrial retrograde signaling is partly responsible for neuronal dysfunction. Sima knockdown also restores function in a Drosophila model of the mitochondrial disease Leigh syndrome and in a Drosophila model of familial Parkinson’s disease. Thus, mitochondrial retrograde signaling regulates neuronal activity and can be manipulated to enhance neuronal function, despite mitochondrial impairment. PMID:26489648

  19. Neurotrophin signalling pathways regulating neuronal apoptosis.

    PubMed

    Miller, F D; Kaplan, D R

    2001-07-01

    Recent evidence indicates that naturally occurring neuronal death in mammals is regulated by the interplay between receptor-mediated prosurvival and proapoptotic signals. The neurotrophins, a family of growth factors best known for their positive effects on neuronal biology, have now been shown to mediate both positive and negative survival signals, by signalling through the Trk and p75 neurotrophin receptors, respectively. The mechanisms whereby these two neurotrophin receptors interact to determine neuronal survival have been difficult to decipher, largely because both can signal independently or coincidentally, depending upon the cell or developmental context. Nonetheless, the past several years have seen significant advances in our understanding of this receptor signalling system. In this review, we focus on the proapoptotic actions of the p75 neurotrophin receptor (p75NTR), and on the interplay between Trk and p75NTR that determines neuronal survival.

  20. Neurotrophin signalling pathways regulating neuronal apoptosis.

    PubMed

    Miller, F D; Kaplan, D R

    2001-07-01

    Recent evidence indicates that naturally occurring neuronal death in mammals is regulated by the interplay between receptor-mediated prosurvival and proapoptotic signals. The neurotrophins, a family of growth factors best known for their positive effects on neuronal biology, have now been shown to mediate both positive and negative survival signals, by signalling through the Trk and p75 neurotrophin receptors, respectively. The mechanisms whereby these two neurotrophin receptors interact to determine neuronal survival have been difficult to decipher, largely because both can signal independently or coincidentally, depending upon the cell or developmental context. Nonetheless, the past several years have seen significant advances in our understanding of this receptor signalling system. In this review, we focus on the proapoptotic actions of the p75 neurotrophin receptor (p75NTR), and on the interplay between Trk and p75NTR that determines neuronal survival. PMID:11529497

  1. c-Jun controls the efficiency of MAP kinase signaling by transcriptional repression of MAP kinase phosphatases

    SciTech Connect

    Sprowles, Amy; Wu Yimi; Kung, H.-J.; Wisdom, Ron . E-mail: ronald.wisdom@ucdmc.ucdavis.edu

    2005-08-15

    The mammalian JNK signaling pathway regulates the transcriptional response of cells to environmental stress, including UV irradiation. This signaling pathway is composed of a classical MAP kinase cascade; activation results in phosphorylation of the transcription factor substrates c-Jun and ATF2, and leads to changes in gene expression. The defining components of this pathway are conserved in the fission yeast S. pombe, where the genetic studies have shown that the ability of the JNK homolog Spc1 to be activated in response to UV irradiation is dependent on the presence of the transcription factor substrate Atf1. We have used genetic analysis to define the role of c-Jun in activation of the mammalian JNK signaling pathway. Our results show that optimal activation of JNK requires the presence of its transcription factor substrate c-Jun. Mutational analysis shows that the ability of c-Jun to support efficient activation of JNK requires the ability of Jun to bind DNA, suggesting a transcriptional mechanism. Consistent with this, we show that c-Jun represses the expression of several MAP kinase phosphatases. In the absence of c-Jun, the increased expression of MAP kinase phosphatases leads to impaired activation of the ERK, JNK, and p38 MAP kinases after pathway activation. The results show that one function of c-Jun is to regulate the efficiency of signaling by the ERK, p38, and JNK MAP kinases, a function that is likely to affect cellular responses to many different stimuli.

  2. METABOLISM Wnt Signaling Regulates Hepatic Metabolism

    PubMed Central

    Liu, Hongjun; Fergusson, Maria M.; Wu, J. Julie; Rovira, Ilsa I.; Liu, Jie; Gavrilova, Oksana; Lu, Teng; Bao, Jianjun; Han, Donghe; Sack, Michael N.; Finkel, Toren

    2011-01-01

    The contribution of the Wnt pathway has been extensively characterized in embryogenesis, differentiation, and stem cell biology but not in mammalian metabolism. Here, using in vivo gain- and loss-of-function models, we demonstrate an important role for Wnt signaling in hepatic metabolism. In particular, β-Catenin, the downstream mediator of canonical Wnt signaling, altered serum glucose concentrations and regulated hepatic glucose production. β-catenin also modulated hepatic insulin signaling. Furthermore, β-catenin interacted with the transcription factor FoxO1 in livers from mice under starved conditions. The interaction of FoxO1 with β-catenin regulated the transcriptional activation of the genes encoding glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK), the two rate-limiting enzymes in hepatic gluconeogenesis. Moreover, starvation induced the hepatic expression of mRNAs encoding different Wnt isoforms. In addition, nutrient deprivation appeared to favor the association of β-catenin with FoxO family members, rather than with members of the T cell factor of transcriptional activators. Notably, in a model of diet-induced obesity, hepatic deletion of β-catenin improved overall metabolic homeostasis. These observations implicate Wnt signaling in the modulation of hepatic metabolism and raise the possibility that Wnt signaling may play a similar role in the metabolic regulation of other tissues. PMID:21285411

  3. Arrestins: ubiquitous regulators of cellular signaling pathways.

    PubMed

    Gurevich, Eugenia V; Gurevich, Vsevolod V

    2006-01-01

    In vertebrates, the arrestins are a family of four proteins that regulate the signaling and trafficking of hundreds of different G-protein-coupled receptors (GPCRs). Arrestin homologs are also found in insects, protochordates and nematodes. Fungi and protists have related proteins but do not have true arrestins. Structural information is available only for free (unbound) vertebrate arrestins, and shows that the conserved overall fold is elongated and composed of two domains, with the core of each domain consisting of a seven-stranded beta-sandwich. Two main intramolecular interactions keep the two domains in the correct relative orientation, but both of these interactions are destabilized in the process of receptor binding, suggesting that the conformation of bound arrestin is quite different. As well as binding to hundreds of GPCR subtypes, arrestins interact with other classes of membrane receptors and more than 20 surprisingly diverse types of soluble signaling protein. Arrestins thus serve as ubiquitous signaling regulators in the cytoplasm and nucleus.

  4. Dynamic Redox Regulation of IL-4 Signaling.

    PubMed

    Dwivedi, Gaurav; Gran, Margaret A; Bagchi, Pritha; Kemp, Melissa L

    2015-11-01

    Quantifying the magnitude and dynamics of protein oxidation during cell signaling is technically challenging. Computational modeling provides tractable, quantitative methods to test hypotheses of redox mechanisms that may be simultaneously operative during signal transduction. The interleukin-4 (IL-4) pathway, which has previously been reported to induce reactive oxygen species and oxidation of PTP1B, may be controlled by several other putative mechanisms of redox regulation; widespread proteomic thiol oxidation observed via 2D redox differential gel electrophoresis upon IL-4 treatment suggests more than one redox-sensitive protein implicated in this pathway. Through computational modeling and a model selection strategy that relied on characteristic STAT6 phosphorylation dynamics of IL-4 signaling, we identified reversible protein tyrosine phosphatase (PTP) oxidation as the primary redox regulatory mechanism in the pathway. A systems-level model of IL-4 signaling was developed that integrates synchronous pan-PTP oxidation with ROS-independent mechanisms. The model quantitatively predicts the dynamics of IL-4 signaling over a broad range of new redox conditions, offers novel hypotheses about regulation of JAK/STAT signaling, and provides a framework for interrogating putative mechanisms involving receptor-initiated oxidation.

  5. Auxin signaling modules regulate maize inflorescence architecture

    PubMed Central

    Galli, Mary; Liu, Qiujie; Moss, Britney L.; Malcomber, Simon; Li, Wei; Gaines, Craig; Federici, Silvia; Roshkovan, Jessica; Meeley, Robert; Nemhauser, Jennifer L.; Gallavotti, Andrea

    2015-01-01

    In plants, small groups of pluripotent stem cells called axillary meristems are required for the formation of the branches and flowers that eventually establish shoot architecture and drive reproductive success. To ensure the proper formation of new axillary meristems, the specification of boundary regions is required for coordinating their development. We have identified two maize genes, BARREN INFLORESCENCE1 and BARREN INFLORESCENCE4 (BIF1 and BIF4), that regulate the early steps required for inflorescence formation. BIF1 and BIF4 encode AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) proteins, which are key components of the auxin hormone signaling pathway that is essential for organogenesis. Here we show that BIF1 and BIF4 are integral to auxin signaling modules that dynamically regulate the expression of BARREN STALK1 (BA1), a basic helix-loop-helix (bHLH) transcriptional regulator necessary for axillary meristem formation that shows a striking boundary expression pattern. These findings suggest that auxin signaling directly controls boundary domains during axillary meristem formation and define a fundamental mechanism that regulates inflorescence architecture in one of the most widely grown crop species. PMID:26464512

  6. Auxin signaling modules regulate maize inflorescence architecture.

    PubMed

    Galli, Mary; Liu, Qiujie; Moss, Britney L; Malcomber, Simon; Li, Wei; Gaines, Craig; Federici, Silvia; Roshkovan, Jessica; Meeley, Robert; Nemhauser, Jennifer L; Gallavotti, Andrea

    2015-10-27

    In plants, small groups of pluripotent stem cells called axillary meristems are required for the formation of the branches and flowers that eventually establish shoot architecture and drive reproductive success. To ensure the proper formation of new axillary meristems, the specification of boundary regions is required for coordinating their development. We have identified two maize genes, BARREN INFLORESCENCE1 and BARREN INFLORESCENCE4 (BIF1 and BIF4), that regulate the early steps required for inflorescence formation. BIF1 and BIF4 encode AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) proteins, which are key components of the auxin hormone signaling pathway that is essential for organogenesis. Here we show that BIF1 and BIF4 are integral to auxin signaling modules that dynamically regulate the expression of BARREN STALK1 (BA1), a basic helix-loop-helix (bHLH) transcriptional regulator necessary for axillary meristem formation that shows a striking boundary expression pattern. These findings suggest that auxin signaling directly controls boundary domains during axillary meristem formation and define a fundamental mechanism that regulates inflorescence architecture in one of the most widely grown crop species.

  7. Regulation of microtubule-based transport by MAP4.

    PubMed

    Semenova, Irina; Ikeda, Kazuho; Resaul, Karim; Kraikivski, Pavel; Aguiar, Mike; Gygi, Steven; Zaliapin, Ilya; Cowan, Ann; Rodionov, Vladimir

    2014-10-15

    Microtubule (MT)-based transport of organelles driven by the opposing MT motors kinesins and dynein is tightly regulated in cells, but the underlying molecular mechanisms remain largely unknown. Here we tested the regulation of MT transport by the ubiquitous protein MAP4 using Xenopus melanophores as an experimental system. In these cells, pigment granules (melanosomes) move along MTs to the cell center (aggregation) or to the periphery (dispersion) by means of cytoplasmic dynein and kinesin-2, respectively. We found that aggregation signals induced phosphorylation of threonine residues in the MT-binding domain of the Xenopus MAP4 (XMAP4), thus decreasing binding of this protein to MTs. Overexpression of XMAP4 inhibited pigment aggregation by shortening dynein-dependent MT runs of melanosomes, whereas removal of XMAP4 from MTs reduced the length of kinesin-2-dependent runs and suppressed pigment dispersion. We hypothesize that binding of XMAP4 to MTs negatively regulates dynein-dependent movement of melanosomes and positively regulates kinesin-2-based movement. Phosphorylation during pigment aggregation reduces binding of XMAP4 to MTs, thus increasing dynein-dependent and decreasing kinesin-2-dependent motility of melanosomes, which stimulates their accumulation in the cell center, whereas dephosphorylation of XMAP4 during dispersion has an opposite effect.

  8. Regulation of microtubule-based transport by MAP4

    PubMed Central

    Semenova, Irina; Ikeda, Kazuho; Resaul, Karim; Kraikivski, Pavel; Aguiar, Mike; Gygi, Steven; Zaliapin, Ilya; Cowan, Ann; Rodionov, Vladimir

    2014-01-01

    Microtubule (MT)-based transport of organelles driven by the opposing MT motors kinesins and dynein is tightly regulated in cells, but the underlying molecular mechanisms remain largely unknown. Here we tested the regulation of MT transport by the ubiquitous protein MAP4 using Xenopus melanophores as an experimental system. In these cells, pigment granules (melanosomes) move along MTs to the cell center (aggregation) or to the periphery (dispersion) by means of cytoplasmic dynein and kinesin-2, respectively. We found that aggregation signals induced phosphorylation of threonine residues in the MT-binding domain of the Xenopus MAP4 (XMAP4), thus decreasing binding of this protein to MTs. Overexpression of XMAP4 inhibited pigment aggregation by shortening dynein-dependent MT runs of melanosomes, whereas removal of XMAP4 from MTs reduced the length of kinesin-2–dependent runs and suppressed pigment dispersion. We hypothesize that binding of XMAP4 to MTs negatively regulates dynein-dependent movement of melanosomes and positively regulates kinesin-2–based movement. Phosphorylation during pigment aggregation reduces binding of XMAP4 to MTs, thus increasing dynein-dependent and decreasing kinesin-2–dependent motility of melanosomes, which stimulates their accumulation in the cell center, whereas dephosphorylation of XMAP4 during dispersion has an opposite effect. PMID:25143402

  9. Testosterone signaling and the regulation of spermatogenesis.

    PubMed

    Walker, William H

    2011-04-01

    Spermatogenesis and male fertility are dependent upon the presence of testosterone in the testis. In the absence of testosterone or the androgen receptor, spermatogenesis does not proceed beyond the meiosis stage. The major cellular target and translator of testosterone signals to developing germ cells is the Sertoli cell. In the Sertoli cell, testosterone signals can be translated directly to changes in gene expression (the classical pathway) or testosterone can activate kinases that may regulate processes required to maintain spermatogenesis (the non-classical pathway). Contributions of the classical and non-classical testosterone signaling pathways to the maintenance of spermatogenesis are discussed. Studies that may further elaborate the mechanisms by with the pathways support spermatogenesis are proposed. PMID:22319659

  10. Localized signals that regulate transendothelial migration.

    PubMed

    Muller, William A

    2016-02-01

    Transendothelial migration (TEM) of leukocytes is the step in leukocyte emigration in which the leukocyte actually leaves the blood vessel to carry out its role in the inflammatory response. It is therefore, arguably the most critical step in emigration. This review focuses on two of the many aspects of this process that have seen important recent developments. The adhesion molecules, PECAM (CD31) and CD99 that regulate two major steps in TEM, do so by regulating specific signals. PECAM initiates the signaling pathway responsible for the calcium flux that is required for TEM. Calcium enters through the cation channel TRPC6 and recruits the first wave of trafficking of membrane from the lateral border recycling compartment (LBRC). CD99 signals through soluble adenylate cyclase to activate protein kinase A to recruit a second wave of LBRC trafficking. Another process that is critical for TEM is transient removal of VE-cadherin from the site of TEM. However, the local signaling pathways that are responsible for this appear to be different from those that open the junctions to increase vascular permeability. PMID:26584476

  11. Signal processing for imaging and mapping ladar

    NASA Astrophysics Data System (ADS)

    Grönwall, Christina; Tolt, Gustav

    2011-11-01

    The new generation laser-based FLASH 3D imaging sensors enable data collection at video rate. This opens up for realtime data analysis but also set demands on the signal processing. In this paper the possibilities and challenges with this new data type are discussed. The commonly used focal plane array based detectors produce range estimates that vary with the target's surface reflectance and target range, and our experience is that the built-in signal processing may not compensate fully for that. We propose a simple adjustment that can be used even if some sensor parameters are not known. The cost for the instantaneous image collection is, compared to scanning laser radar systems, lower range accuracy. By gathering range information from several frames the geometrical information of the target can be obtained. We also present an approach of how range data can be used to remove foreground clutter in front of a target. Further, we illustrate how range data enables target classification in near real-time and that the results can be improved if several frames are co-registered. Examples using data from forest and maritime scenes are shown.

  12. Fibroblast growth factor 8 organizes the neocortical area map and regulates sensory map topography.

    PubMed

    Assimacopoulos, Stavroula; Kao, Tina; Issa, Naoum P; Grove, Elizabeth A

    2012-05-23

    The concept of an "organizer" is basic to embryology. An organizer is a portion of the embryo producing signals that lead to the creation of a patterned mature structure from an embryonic primordium. Fibroblast growth factor 8 (FGF8) is a morphogen that disperses from a rostromedial source in the neocortical primordium (NP), forms a rostral-to-caudal (R/C) gradient, and regulates embryonic and neonatal R/C patterns of gene expression in neocortex. Whether FGF8 also has organizer activity that generates the postnatal neocortical area map is uncertain. To test this possibility, new sources of FGF8 were introduced into the mouse NP with in utero microelectroporation at embryonic day 10.5, close to the estimated peak of area patterning. Results differed depending on the position of ectopic FGF8. Ectopic FGF8 in the caudalmost NP could duplicate somatosensory cortex (S1) and primary visual cortex (V1). FGF8 delivered to the midlateral NP generated a sulcus separating rostral and caudal portions of the NP, in effect creating duplicate NPs. In the caudal NP, ectopic FGF8 induced a second, inclusive area map, containing frontal cortex, S1, V1, and primary auditory areas. Moreover, duplicate S1 showed plasticity to sensory deprivation, and duplicate V1 responded to visual stimuli. Our findings implicate FGF8 as an organizer signal, and its source in the rostromedial telencephalon as an organizer of the neocortical area map. PMID:22623663

  13. Regulation of Redox Signaling by Selenoproteins

    PubMed Central

    Alkan, Zeynep

    2010-01-01

    The unique chemistry of oxygen has been both a resource and threat for life on Earth for at least the last 2.4 billion years. Reduction of oxygen to water allows extraction of more metabolic energy from organic fuels than is possible through anaerobic glycolysis. On the other hand, partially reduced oxygen can react indiscriminately with biomolecules to cause genetic damage, disease, and even death. Organisms in all three superkingdoms of life have developed elaborate mechanisms to protect against such oxidative damage and to exploit reactive oxygen species as sensors and signals in myriad processes. The sulfur amino acids, cysteine and methionine, are the main targets of reactive oxygen species in proteins. Oxidative modifications to cysteine and methionine can have profound effects on a protein’s activity, structure, stability, and subcellular localization. Non-reversible oxidative modifications (oxidative damage) may contribute to molecular, cellular, and organismal aging and serve as signals for repair, removal, or programmed cell death. Reversible oxidation events can function as transient signals of physiological status, extracellular environment, nutrient availability, metabolic state, cell cycle phase, immune function, or sensory stimuli. Because of its chemical similarity to sulfur and stronger nucleophilicity and acidity, selenium is an extremely efficient catalyst of reactions between sulfur and oxygen. Most of the biological activity of selenium is due to selenoproteins containing selenocysteine, the 21st genetically encoded protein amino acid. The most abundant selenoproteins in mammals are the glutathione peroxidases (five to six genes) that reduce hydrogen peroxide and lipid hydroperoxides at the expense of glutathione and serve to limit the strength and duration of reactive oxygen signals. Thioredoxin reductases (three genes) use nicotinamide adenine dinucleotide phosphate to reduce oxidized thioredoxin and its homologs, which regulate a plethora

  14. Regulation of redox signaling by selenoproteins.

    PubMed

    Hawkes, Wayne Chris; Alkan, Zeynep

    2010-06-01

    The unique chemistry of oxygen has been both a resource and threat for life on Earth for at least the last 2.4 billion years. Reduction of oxygen to water allows extraction of more metabolic energy from organic fuels than is possible through anaerobic glycolysis. On the other hand, partially reduced oxygen can react indiscriminately with biomolecules to cause genetic damage, disease, and even death. Organisms in all three superkingdoms of life have developed elaborate mechanisms to protect against such oxidative damage and to exploit reactive oxygen species as sensors and signals in myriad processes. The sulfur amino acids, cysteine and methionine, are the main targets of reactive oxygen species in proteins. Oxidative modifications to cysteine and methionine can have profound effects on a protein's activity, structure, stability, and subcellular localization. Non-reversible oxidative modifications (oxidative damage) may contribute to molecular, cellular, and organismal aging and serve as signals for repair, removal, or programmed cell death. Reversible oxidation events can function as transient signals of physiological status, extracellular environment, nutrient availability, metabolic state, cell cycle phase, immune function, or sensory stimuli. Because of its chemical similarity to sulfur and stronger nucleophilicity and acidity, selenium is an extremely efficient catalyst of reactions between sulfur and oxygen. Most of the biological activity of selenium is due to selenoproteins containing selenocysteine, the 21st genetically encoded protein amino acid. The most abundant selenoproteins in mammals are the glutathione peroxidases (five to six genes) that reduce hydrogen peroxide and lipid hydroperoxides at the expense of glutathione and serve to limit the strength and duration of reactive oxygen signals. Thioredoxin reductases (three genes) use nicotinamide adenine dinucleotide phosphate to reduce oxidized thioredoxin and its homologs, which regulate a plethora of

  15. Astrocytes regulate adult hippocampal neurogenesis through ephrin-B signaling

    PubMed Central

    Ashton, Randolph S.; Conway, Anthony; Pangarkar, Chinmay; Bergen, Jamie; Lim, Kwang-Il; Shah, Priya; Bissell, Mina; Schaffer, David V.

    2012-01-01

    Neurogenesis in the adult hippocampus involves activation of quiescent neural stem cells (NSCs) to yield transiently amplifying NSCs and progenitors, and ultimately neurons that affect learning and memory. This process is tightly controlled by microenvironmental cues, though few endogenous factors are known to regulate neuronal differentiation. While astrocytes have been implicated, their role in juxtacrine (i.e. cell-cell contact-dependent) signaling within NSC niches has not been investigated. We show that ephrin-B2 presented from rodent hippocampal astrocytes regulates neurogenesis in vivo. Furthermore, clonal analysis in NSC fate-mapping studies reveals a novel role for ephrin-B2 in instructing neuronal differentiation. Additionally, ephrin-B2 signaling, transduced by EphB4 receptors on NSCs, activates β-catenin in vitro and in vivo independent of Wnt signaling and upregulates proneural transcription factors. Ephrin-B2+ astrocytes thus promote neuronal differentiation of adult NSCs through juxtacrine signaling, findings that advance our understanding of adult neurogenesis and may have future regenerative medicine implications. PMID:22983209

  16. Evolutionarily conserved regulation of TOR signalling.

    PubMed

    Takahara, Terunao; Maeda, Tatsuya

    2013-07-01

    The target of rapamycin (TOR) is an evolutionarily conserved protein kinase that regulates cell growth in response to various environmental as well as intracellular cues through the formation of 2 distinct TOR complexes (TORC), TORC1 and TORC2. Dysregulation of TORC1 and TORC2 activity is closely associated with various diseases, including diabetes, cancer and neurodegenerative disorders. Over the past few years, new regulatory mechanisms of TORC1 and TORC2 activity have been elucidated. Furthermore, recent advances in the study of TOR inhibitors have revealed previously unrecognized cellular functions of TORC1. In this review, we briefly summarize the current understanding of the evolutionarily conserved TOR signalling from upstream regulators to downstream events.

  17. β-Arrestin drives MAP kinase signalling from clathrin-coated structures after GPCR dissociation.

    PubMed

    Eichel, K; Jullié, D; von Zastrow, M

    2016-03-01

    β-Arrestins critically regulate G-protein-coupled receptor (GPCR) signalling, not only 'arresting' the G protein signal but also modulating endocytosis and initiating a discrete G-protein-independent signal through MAP kinase. Despite enormous recent progress towards understanding biophysical aspects of arrestin function, arrestin cell biology remains relatively poorly understood. Two key tenets underlie the prevailing current view: β-arrestin accumulates in clathrin-coated structures (CCSs) exclusively in physical complex with its activating GPCR, and MAP kinase activation requires endocytosis of formed GPCR-β-arrestin complexes. We show here, using β1-adrenergic receptors, that β-arrestin-2 (arrestin 3) accumulates robustly in CCSs after dissociating from its activating GPCR and transduces the MAP kinase signal from CCSs. Moreover, inhibiting subsequent endocytosis of CCSs enhances the clathrin- and β-arrestin-dependent MAP kinase signal. These results demonstrate β-arrestin 'activation at a distance', after dissociating from its activating GPCR, and signalling from CCSs. We propose a β-arrestin signalling cycle that is catalytically activated by the GPCR and energetically coupled to the endocytic machinery.

  18. β-arrestin drives MAP kinase signaling from clathrin-coated structures after GPCR dissociation

    PubMed Central

    Eichel, K.; Jullié, D.

    2016-01-01

    β-arrestins critically regulate G protein-coupled receptor (GPCR) signaling, not only 'arresting' the G protein signal but also modulating endocytosis and initiating a discrete G protein-independent signal via MAP kinase1–3. Despite enormous recent progress toward understanding biophysical aspects of arrestin function4,5, its cell biology remains relatively poorly understood. Two key tenets underlie the present dogma: (1) β-arrestin accumulates in clathrin-coated structures (CCSs) exclusively in physical complex with its activating GPCR, and (2) MAP kinase activation requires endocytosis of formed GPCR - β-arrestin complexes6–9. We show here, using β1-adrenergic receptors, that β-arrestin-2 (Arrestin 3) accumulates robustly in CCSs after dissociating from its activating GPCR and transduces the MAP kinase signal from CCSs. Moreover, inhibiting subsequent endocytosis of CCSs enhances the clathrin and β-arrestin -dependent MAP kinase signal. These results demonstrate β-arrestin 'activation at a distance', after dissociating from its activating GPCR, and signaling from CCSs. We propose a β-arrestin signaling cycle that is catalytically activated by the GPCR and energetically coupled to the endocytic machinery. PMID:26829388

  19. β-Arrestin drives MAP kinase signalling from clathrin-coated structures after GPCR dissociation.

    PubMed

    Eichel, K; Jullié, D; von Zastrow, M

    2016-03-01

    β-Arrestins critically regulate G-protein-coupled receptor (GPCR) signalling, not only 'arresting' the G protein signal but also modulating endocytosis and initiating a discrete G-protein-independent signal through MAP kinase. Despite enormous recent progress towards understanding biophysical aspects of arrestin function, arrestin cell biology remains relatively poorly understood. Two key tenets underlie the prevailing current view: β-arrestin accumulates in clathrin-coated structures (CCSs) exclusively in physical complex with its activating GPCR, and MAP kinase activation requires endocytosis of formed GPCR-β-arrestin complexes. We show here, using β1-adrenergic receptors, that β-arrestin-2 (arrestin 3) accumulates robustly in CCSs after dissociating from its activating GPCR and transduces the MAP kinase signal from CCSs. Moreover, inhibiting subsequent endocytosis of CCSs enhances the clathrin- and β-arrestin-dependent MAP kinase signal. These results demonstrate β-arrestin 'activation at a distance', after dissociating from its activating GPCR, and signalling from CCSs. We propose a β-arrestin signalling cycle that is catalytically activated by the GPCR and energetically coupled to the endocytic machinery. PMID:26829388

  20. MAP3K1 functionally interacts with Axin1 in the canonical Wnt signalling pathway.

    PubMed

    Sue Ng, Ser; Mahmoudi, Tokameh; Li, Vivian S W; Hatzis, Pantelis; Boersema, Paul J; Mohammed, Shabaz; Heck, Albert J; Clevers, Hans

    2010-01-01

    A central point of regulation in the Wnt/beta-catenin signalling pathway is the formation of the beta-catenin destruction complex. Axin1, an essential negative regulator of Wnt signalling, serves as a scaffold within this complex and is critical for rapid turnover of beta-catenin. To examine the mechanism by which Wnt signalling disables the destruction complex, we used an immunoprecipitation-coupled proteomics approach to identify novel endogenous binding partners of Axin1. We found mitogen-activated protein kinase kinase kinase 1 (MAP3K1) as an Axin1 interactor in Ls174T colorectal cancer (CRC) cells. Importantly, confirmation of this interaction in HEK293T cells indicated that the Axin1-MAP3K1 interaction is induced and modulated by Wnt stimulation. siRNA depletion of MAP3K1 specifically abrogated TCF/LEF-driven transcription and Wnt3A-driven endogenous gene expression in both HEK293T as well as DLD-1 CRC. Expression of ubiquitin ligase mutants of MAP3K1 abrogated TCF/LEF transcription, whereas kinase mutants had no effect in TCF-driven activity, highlighting the essential role of the MAP3K1 E3 ubiquitin ligase activity in regulation of the Wnt/beta-catenin pathway. These results suggest that MAP3K1, previously reported as an Axin1 inter-actor in c-Jun NH(2)-terminal kinase pathway, is also involved in the canonical Wnt signalling pathway and positively regulates expression of Wnt target genes. PMID:20128690

  1. Mapping the functional versatility and fragility of Ras GTPase signaling circuits through in vitro network reconstitution.

    PubMed

    Coyle, Scott M; Lim, Wendell A

    2016-01-01

    The Ras-superfamily GTPases are central controllers of cell proliferation and morphology. Ras signaling is mediated by a system of interacting molecules: upstream enzymes (GEF/GAP) regulate Ras's ability to recruit multiple competing downstream effectors. We developed a multiplexed, multi-turnover assay for measuring the dynamic signaling behavior of in vitro reconstituted H-Ras signaling systems. By including both upstream regulators and downstream effectors, we can systematically map how different network configurations shape the dynamic system response. The concentration and identity of both upstream and downstream signaling components strongly impacted the timing, duration, shape, and amplitude of effector outputs. The distorted output of oncogenic alleles of Ras was highly dependent on the balance of positive (GAP) and negative (GEF) regulators in the system. We found that different effectors interpreted the same inputs with distinct output dynamics, enabling a Ras system to encode multiple unique temporal outputs in response to a single input. We also found that different Ras-to-GEF positive feedback mechanisms could reshape output dynamics in distinct ways, such as signal amplification or overshoot minimization. Mapping of the space of output behaviors accessible to Ras provides a design manual for programming Ras circuits, and reveals how these systems are readily adapted to produce an array of dynamic signaling behaviors. Nonetheless, this versatility comes with a trade-off of fragility, as there exist numerous paths to altered signaling behaviors that could cause disease. PMID:26765565

  2. Fibroblast Growth Factor Signaling in Metabolic Regulation.

    PubMed

    Nies, Vera J M; Sancar, Gencer; Liu, Weilin; van Zutphen, Tim; Struik, Dicky; Yu, Ruth T; Atkins, Annette R; Evans, Ronald M; Jonker, Johan W; Downes, Michael Robert

    2015-01-01

    The prevalence of obesity is a growing health problem. Obesity is strongly associated with several comorbidities, such as non-alcoholic fatty liver disease, certain cancers, insulin resistance, and type 2 diabetes, which all reduce life expectancy and life quality. Several drugs have been put forward in order to treat these diseases, but many of them have detrimental side effects. The unexpected role of the family of fibroblast growth factors in the regulation of energy metabolism provides new approaches to the treatment of metabolic diseases and offers a valuable tool to gain more insight into metabolic regulation. The known beneficial effects of FGF19 and FGF21 on metabolism, together with recently discovered similar effects of FGF1 suggest that FGFs and their derivatives carry great potential as novel therapeutics to treat metabolic conditions. To facilitate the development of new therapies with improved targeting and minimal side effects, a better understanding of the molecular mechanism of action of FGFs is needed. In this review, we will discuss what is currently known about the physiological roles of FGF signaling in tissues important for metabolic homeostasis. In addition, we will discuss current concepts regarding their pharmacological properties and effector tissues in the context of metabolic disease. Also, the recent progress in the development of FGF variants will be reviewed. Our goal is to provide a comprehensive overview of the current concepts and consensuses regarding FGF signaling in metabolic health and disease and to provide starting points for the development of FGF-based therapies against metabolic conditions.

  3. Bioelectric Signaling Regulates Size in Zebrafish Fins

    PubMed Central

    Perathoner, Simon; Daane, Jacob M.; Henrion, Ulrike; Seebohm, Guiscard; Higdon, Charles W.; Johnson, Stephen L.; Nüsslein-Volhard, Christiane; Harris, Matthew P.

    2014-01-01

    The scaling relationship between the size of an appendage or organ and that of the body as a whole is tightly regulated during animal development. If a structure grows at a different rate than the rest of the body, this process is termed allometric growth. The zebrafish another longfin (alf) mutant shows allometric growth resulting in proportionally enlarged fins and barbels. We took advantage of this mutant to study the regulation of size in vertebrates. Here, we show that alf mutants carry gain-of-function mutations in kcnk5b, a gene encoding a two-pore domain potassium (K+) channel. Electrophysiological analysis in Xenopus oocytes reveals that these mutations cause an increase in K+ conductance of the channel and lead to hyperpolarization of the cell. Further, somatic transgenesis experiments indicate that kcnk5b acts locally within the mesenchyme of fins and barbels to specify appendage size. Finally, we show that the channel requires the ability to conduct K+ ions to increase the size of these structures. Our results provide evidence for a role of bioelectric signaling through K+ channels in the regulation of allometric scaling and coordination of growth in the zebrafish. PMID:24453984

  4. Fibroblast Growth Factor Signaling in Metabolic Regulation

    PubMed Central

    Nies, Vera J. M.; Sancar, Gencer; Liu, Weilin; van Zutphen, Tim; Struik, Dicky; Yu, Ruth T.; Atkins, Annette R.; Evans, Ronald M.; Jonker, Johan W.; Downes, Michael Robert

    2016-01-01

    The prevalence of obesity is a growing health problem. Obesity is strongly associated with several comorbidities, such as non-alcoholic fatty liver disease, certain cancers, insulin resistance, and type 2 diabetes, which all reduce life expectancy and life quality. Several drugs have been put forward in order to treat these diseases, but many of them have detrimental side effects. The unexpected role of the family of fibroblast growth factors in the regulation of energy metabolism provides new approaches to the treatment of metabolic diseases and offers a valuable tool to gain more insight into metabolic regulation. The known beneficial effects of FGF19 and FGF21 on metabolism, together with recently discovered similar effects of FGF1 suggest that FGFs and their derivatives carry great potential as novel therapeutics to treat metabolic conditions. To facilitate the development of new therapies with improved targeting and minimal side effects, a better understanding of the molecular mechanism of action of FGFs is needed. In this review, we will discuss what is currently known about the physiological roles of FGF signaling in tissues important for metabolic homeostasis. In addition, we will discuss current concepts regarding their pharmacological properties and effector tissues in the context of metabolic disease. Also, the recent progress in the development of FGF variants will be reviewed. Our goal is to provide a comprehensive overview of the current concepts and consensuses regarding FGF signaling in metabolic health and disease and to provide starting points for the development of FGF-based therapies against metabolic conditions. PMID:26834701

  5. Learning-regulated context relevant topographical map.

    PubMed

    Hartono, Pitoyo; Hollensen, Paul; Trappenberg, Thomas

    2015-10-01

    Kohonen's self-organizing map (SOM) is used to map high-dimensional data into a low-dimensional representation (typically a 2-D or 3-D space) while preserving their topological characteristics. A major reason for its application is to be able to visualize data while preserving their relation in the high-dimensional input data space as much as possible. Here, we are seeking to go further by incorporating semantic meaning in the low-dimensional representation. In a conventional SOM, the semantic context of the data, such as class labels, does not have any influence on the formation of the map. As an abstraction of neural function, the SOM models bottom-up self-organization but not feedback modulation which is also ubiquitous in the brain. In this paper, we demonstrate a hierarchical neural network, which learns a topographical map that also reflects the semantic context of the data. Our method combines unsupervised, bottom-up topographical map formation with top-down supervised learning. We discuss the mathematical properties of the proposed hierarchical neural network and demonstrate its abilities with empirical experiments.

  6. Learning-regulated context relevant topographical map.

    PubMed

    Hartono, Pitoyo; Hollensen, Paul; Trappenberg, Thomas

    2015-10-01

    Kohonen's self-organizing map (SOM) is used to map high-dimensional data into a low-dimensional representation (typically a 2-D or 3-D space) while preserving their topological characteristics. A major reason for its application is to be able to visualize data while preserving their relation in the high-dimensional input data space as much as possible. Here, we are seeking to go further by incorporating semantic meaning in the low-dimensional representation. In a conventional SOM, the semantic context of the data, such as class labels, does not have any influence on the formation of the map. As an abstraction of neural function, the SOM models bottom-up self-organization but not feedback modulation which is also ubiquitous in the brain. In this paper, we demonstrate a hierarchical neural network, which learns a topographical map that also reflects the semantic context of the data. Our method combines unsupervised, bottom-up topographical map formation with top-down supervised learning. We discuss the mathematical properties of the proposed hierarchical neural network and demonstrate its abilities with empirical experiments. PMID:25546864

  7. Specificity of MAP kinase signaling in yeast differentiation involves transient versus sustained MAPK activation.

    PubMed

    Sabbagh, W; Flatauer, L J; Bardwell, A J; Bardwell, L

    2001-09-01

    Signals transmitted by common components often elicit distinct (yet appropriate) outcomes. In yeast, two developmental options-mating and invasive growth-are both regulated by the same MAP kinase cascade. Specificity has been thought to result from specialized roles for the two MAP kinases, Kss1 and Fus3, and because Fus3 prevents Kss1 from gaining access to the mating pathway. Kss1 has been thought to participate in mating only when Fus3 is absent. Instead, we show that Kss1 is rapidly phosphorylated and potently activated by mating pheromone in wild-type cells, and that this is required for normal pheromone-induced gene expression. Signal identity is apparently maintained because active Fus3 limits the extent of Kss1 activation, thereby preventing inappropriate signal crossover. PMID:11583629

  8. The role of MAP4K3 in lifespan regulation of Caenorhabditiselegans

    SciTech Connect

    Khan, Maruf H.; Hart, Matthew J.; Rea, Shane L.

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Inhibition of MAP4K3 by RNAi leads to increased mean lifespan in Caenorhabditis elegans. Black-Right-Pointing-Pointer Mutation in the citron homology domain of MAP4K3 leads to increased mean lifespan. Black-Right-Pointing-Pointer Mutation in the kinase domain of MAP4K3 has no significant effect on mean lifespan. -- Abstract: The TOR pathway is a kinase signaling pathway that regulates cellular growth and proliferation in response to nutrients and growth factors. TOR signaling is also important in lifespan regulation - when this pathway is inhibited, either naturally, by genetic mutation, or by pharmacological means, lifespan is extended. MAP4K3 is a Ser/Thr kinase that has recently been found to be involved in TOR activation. Unexpectedly, the effect of this protein is not mediated via Rheb, the more widely known TOR activation pathway. Given the role of TOR in growth and lifespan control, we looked at how inhibiting MAP4K3 in Caenorhabditiselegans affects lifespan. We used both feeding RNAi and genetic mutants to look at the effect of MAP4K3 deficiency. Our results show a small but significant increase in mean lifespan in MAP4K3 deficient worms. MAP4K3 thus represents a new target in the TOR pathway that can be targeted for pharmacological intervention to control lifespan.

  9. praja2 regulates KSR1 stability and mitogenic signaling

    PubMed Central

    Rinaldi, L; Delle Donne, R; Sepe, M; Porpora, M; Garbi, C; Chiuso, F; Gallo, A; Parisi, S; Russo, L; Bachmann, V; Huber, R G; Stefan, E; Russo, T; Feliciello, A

    2016-01-01

    The kinase suppressor of Ras 1 (KSR1) has a fundamental role in mitogenic signaling by scaffolding components of the Ras/MAP kinase pathway. In response to Ras activation, KSR1 assembles a tripartite kinase complex that optimally transfers signals generated at the cell membrane to activate ERK. We describe a novel mechanism of ERK attenuation based on ubiquitin-dependent proteolysis of KSR1. Stimulation of membrane receptors by hormones or growth factors induced KSR1 polyubiquitination, which paralleled a decline of ERK1/2 signaling. We identified praja2 as the E3 ligase that ubiquitylates KSR1. We showed that praja2-dependent regulation of KSR1 is involved in the growth of cancer cells and in the maintenance of undifferentiated pluripotent state in mouse embryonic stem cells. The dynamic interplay between the ubiquitin system and the kinase scaffold of the Ras pathway shapes the activation profile of the mitogenic cascade. By controlling KSR1 levels, praja2 directly affects compartmentalized ERK activities, impacting on physiological events required for cell proliferation and maintenance of embryonic stem cell pluripotency. PMID:27195677

  10. SIGNALS AND REGULATORS THAT GOVERN STREPTOMYCES DEVELOPMENT

    PubMed Central

    McCormick, Joseph R.; Flärdh, Klas

    2012-01-01

    Streptomyces coelicolor is the genetically best characterized species of a populous genus belonging to the Gram-positive Actinobacteria. Streptomycetes are filamentous soil organisms, well known for the production of a plethora of biologically active secondary metabolic compounds. The Streptomyces developmental life cycle is uniquely complex, and involves coordinated multicellular development with both physiological and morphological differentiation of several cell types, culminating in production of secondary metabolites and dispersal of mature spores. This review presents a current appreciation of the signaling mechanisms used to orchestrate the decision to undergo morphological differentiation, and the regulators and regulatory networks that direct the intriguing development of multigenomic hyphae, first to form specialized aerial hyphae, and then to convert them into chains of dormant spores. This current view of S. coelicolor development is destined for rapid evolution as data from “-omics” studies shed light on gene regulatory networks, new genetic screens identify hitherto unknown players, and the resolution of our insights into the underlying cell biological processes steadily improve. PMID:22092088

  11. A divergent canonical WNT-signaling pathway regulates microtubule dynamics

    PubMed Central

    Ciani, Lorenza; Krylova, Olga; Smalley, Matthew J.; Dale, Trevor C.; Salinas, Patricia C.

    2004-01-01

    Dishevelled (DVL) is associated with axonal microtubules and regulates microtubule stability through the inhibition of the serine/threonine kinase, glycogen synthase kinase 3β (GSK-3β). In the canonical WNT pathway, the negative regulator Axin forms a complex with β-catenin and GSK-3β, resulting in β-catenin degradation. Inhibition of GSK-3β by DVL increases β-catenin stability and TCF transcriptional activation. Here, we show that Axin associates with microtubules and unexpectedly stabilizes microtubules through DVL. In turn, DVL stabilizes microtubules by inhibiting GSK-3β through a transcription- and β-catenin–independent pathway. More importantly, axonal microtubules are stabilized after DVL localizes to axons. Increased microtubule stability is correlated with a decrease in GSK-3β–mediated phosphorylation of MAP-1B. We propose a model in which Axin, through DVL, stabilizes microtubules by inhibiting a pool of GSK-3β, resulting in local changes in the phosphorylation of cellular targets. Our data indicate a bifurcation in the so-called canonical WNT-signaling pathway to regulate microtubule stability. PMID:14734535

  12. Mapping the functional versatility and fragility of Ras GTPase signaling circuits through in vitro network reconstitution

    PubMed Central

    Coyle, Scott M; Lim, Wendell A

    2016-01-01

    The Ras-superfamily GTPases are central controllers of cell proliferation and morphology. Ras signaling is mediated by a system of interacting molecules: upstream enzymes (GEF/GAP) regulate Ras’s ability to recruit multiple competing downstream effectors. We developed a multiplexed, multi-turnover assay for measuring the dynamic signaling behavior of in vitro reconstituted H-Ras signaling systems. By including both upstream regulators and downstream effectors, we can systematically map how different network configurations shape the dynamic system response. The concentration and identity of both upstream and downstream signaling components strongly impacted the timing, duration, shape, and amplitude of effector outputs. The distorted output of oncogenic alleles of Ras was highly dependent on the balance of positive (GAP) and negative (GEF) regulators in the system. We found that different effectors interpreted the same inputs with distinct output dynamics, enabling a Ras system to encode multiple unique temporal outputs in response to a single input. We also found that different Ras-to-GEF positive feedback mechanisms could reshape output dynamics in distinct ways, such as signal amplification or overshoot minimization. Mapping of the space of output behaviors accessible to Ras provides a design manual for programming Ras circuits, and reveals how these systems are readily adapted to produce an array of dynamic signaling behaviors. Nonetheless, this versatility comes with a trade-off of fragility, as there exist numerous paths to altered signaling behaviors that could cause disease. DOI: http://dx.doi.org/10.7554/eLife.12435.001 PMID:26765565

  13. Visual Map Development: Bidirectional Signaling, Bifunctional Guidance Molecules, and Competition

    PubMed Central

    Feldheim, David A.; O’Leary, Dennis D. M.

    2010-01-01

    Topographic maps are a two-dimensional representation of one neural structure within another and serve as the main strategy to organize sensory information. The retina’s projection via axons of retinal ganglion cells to midbrain visual centers, the optic tectum/superior colliculus, is the leading model to elucidate mechanisms of topographic map formation. Each axis of the retina is mapped independently using different mechanisms and sets of axon guidance molecules expressed in gradients to achieve the goal of representing a point in the retina onto a point within the target. An axon’s termination along the temporal-nasal mapping axis is determined by opposing gradients of EphAs and ephrin-As that act through their forward and reverse signaling, respectively, within the projecting axons, each of which inhibits interstitial branching, cooperating with a branch-promoting activity, to generate topographic specific branching along the shaft of the parent axons that overshoot their correct termination zone along the anterior-posterior axis of the target. The dorsal-ventral termination position is then determined using a gradient of ephrin-B that can act as a repellent or attractant depending on the ephrin-B concentration relative to EphB levels on the interstitial branches to guide them along the medial-lateral axis of the target to their correct termination zone, where they arborize. In both cases, axon-axon competition results in axon mapping based on relative rather than absolute levels of repellent or attractant activity. The map is subsequently refined through large-scale pruning driven in large part by patterned retinal activity. PMID:20880989

  14. Molecular basis of MAP kinase regulation

    PubMed Central

    Peti, Wolfgang; Page, Rebecca

    2013-01-01

    Mitogen-activated protein kinases (MAPKs; ERK1/2, p38, JNK, and ERK5) have evolved to transduce environmental and developmental signals (growth factors, stress) into adaptive and programmed responses (differentiation, inflammation, apoptosis). Almost 20 years ago, it was discovered that MAPKs contain a docking site in the C-terminal lobe that binds a conserved 13-16 amino acid sequence known as the D- or KIM-motif (kinase interaction motif). Recent crystal structures of MAPK:KIM-peptide complexes are leading to a precise understanding of how KIM sequences contribute to MAPK selectivity. In addition, new crystal and especially NMR studies are revealing how residues outside the canonical KIM motif interact with specific MAPKs and contribute further to MAPK selectivity and signaling pathway fidelity. In this review, we focus on these recent studies, with an emphasis on the use of NMR spectroscopy, isothermal titration calorimetry and small angle X-ray scattering to investigate these processes. PMID:24115095

  15. Caveolin-1 regulates shear stress-dependent activation of extracellular signal-regulated kinase

    NASA Technical Reports Server (NTRS)

    Park, H.; Go, Y. M.; Darji, R.; Choi, J. W.; Lisanti, M. P.; Maland, M. C.; Jo, H.

    2000-01-01

    Fluid shear stress activates a member of the mitogen-activated protein (MAP) kinase family, extracellular signal-regulated kinase (ERK), by mechanisms dependent on cholesterol in the plasma membrane in bovine aortic endothelial cells (BAEC). Caveolae are microdomains of the plasma membrane that are enriched with cholesterol, caveolin, and signaling molecules. We hypothesized that caveolin-1 regulates shear activation of ERK. Because caveolin-1 is not exposed to the outside, cells were minimally permeabilized by Triton X-100 (0.01%) to deliver a neutralizing, polyclonal caveolin-1 antibody (pCav-1) inside the cells. pCav-1 then bound to caveolin-1 and inhibited shear activation of ERK but not c-Jun NH(2)-terminal kinase. Epitope mapping studies showed that pCav-1 binds to caveolin-1 at two regions (residues 1-21 and 61-101). When the recombinant proteins containing the epitopes fused to glutathione-S-transferase (GST-Cav(1-21) or GST-Cav(61-101)) were preincubated with pCav-1, only GST-Cav(61-101) reversed the inhibitory effect of the antibody on shear activation of ERK. Other antibodies, including m2234, which binds to caveolin-1 residues 1-21, had no effect on shear activation of ERK. Caveolin-1 residues 61-101 contain the scaffolding and oligomerization domains, suggesting that binding of pCav-1 to these regions likely disrupts the clustering of caveolin-1 or its interaction with signaling molecules involved in the shear-sensitive ERK pathway. We suggest that caveolae-like domains play a critical role in the mechanosensing and/or mechanosignal transduction of the ERK pathway.

  16. Develop Advanced Nonlinear Signal Analysis Topographical Mapping System

    NASA Technical Reports Server (NTRS)

    Jong, Jen-Yi

    1997-01-01

    During the development of the SSME, a hierarchy of advanced signal analysis techniques for mechanical signature analysis has been developed by NASA and AI Signal Research Inc. (ASRI) to improve the safety and reliability for Space Shuttle operations. These techniques can process and identify intelligent information hidden in a measured signal which is often unidentifiable using conventional signal analysis methods. Currently, due to the highly interactive processing requirements and the volume of dynamic data involved, detailed diagnostic analysis is being performed manually which requires immense man-hours with extensive human interface. To overcome this manual process, NASA implemented this program to develop an Advanced nonlinear signal Analysis Topographical Mapping System (ATMS) to provide automatic/unsupervised engine diagnostic capabilities. The ATMS will utilize a rule-based Clips expert system to supervise a hierarchy of diagnostic signature analysis techniques in the Advanced Signal Analysis Library (ASAL). ASAL will perform automatic signal processing, archiving, and anomaly detection/identification tasks in order to provide an intelligent and fully automated engine diagnostic capability. The ATMS has been successfully developed under this contract. In summary, the program objectives to design, develop, test and conduct performance evaluation for an automated engine diagnostic system have been successfully achieved. Software implementation of the entire ATMS system on MSFC's OISPS computer has been completed. The significance of the ATMS developed under this program is attributed to the fully automated coherence analysis capability for anomaly detection and identification which can greatly enhance the power and reliability of engine diagnostic evaluation. The results have demonstrated that ATMS can significantly save time and man-hours in performing engine test/flight data analysis and performance evaluation of large volumes of dynamic test data.

  17. [Zinc signaling-mediated regulation of dentin and periodontal tissues].

    PubMed

    Fukada, Toshiyuki; Idaira, Yayoi; Shimoda, Shinji; Asada, Yoshinobu

    2015-12-01

    An essential trace element zinc is required for variety of cellular functions and physiological responses, therefore, downregulation of zinc homeostasis cause serious problems in health, such as growth retardation and abnormal bone formation. Recent technical advances contributed to reveal that zinc ion regulated by zinc transporters acts as a signaling mediator, called zinc signaling that involves in mammalian physiology and pathogenesis. This review will address the current understanding of the roles of zinc signaling in regulation of dentin formation and periodontal tissues homeostasis.

  18. Functional mapping of interacting regions of the photoreceptor phosphodiesterase (PDE6) γ-subunit with PDE6 catalytic dimer, transducin, and regulator of G-protein signaling9-1 (RGS9-1).

    PubMed

    Zhang, Xiu-Jun; Gao, Xiong-Zhuo; Yao, Wei; Cote, Rick H

    2012-07-27

    The cGMP phosphodiesterase (PDE6) involved in visual transduction in photoreceptor cells contains two inhibitory γ-subunits (Pγ) which bind to the catalytic core (Pαβ) to inhibit catalysis and stimulate cGMP binding to the GAF domains of Pαβ. During visual excitation, interaction of activated transducin with Pγ relieves inhibition. Pγ also participates in a complex with RGS9-1 and other proteins to accelerate the GTPase activity of activated transducin. We studied the structural determinants for these important functions of Pγ. First, we identified two important sites in the middle region of Pγ (amino acids 27-38 and 52-54) that significantly stabilize the overall binding affinity of Pγ with Pαβ. The ability of Pγ to stimulate noncatalytic cGMP binding to the GAF domains of PDE6 has been localized to amino acids 27-30 of Pγ. Transducin activation of PDE6 catalysis critically depends on the presence of Ile54 in the glycine-rich region of Pγ in order to relieve inhibition of catalysis. The central glycine-rich region of Pγ is also required for transducin to increase cGMP exchange at the GAF domains. Finally, Thr-65 and/or Val-66 of Pγ are critical residues for Pγ to stimulate GTPase activity of transducin in a complex with RGS9-1. We propose that the glycine-rich region of Pγ is a primary docking site for PDE6-interacting proteins involved in the activation/inactivation pathways of visual transduction. This functional mapping of Pγ with its binding partners demonstrates the remarkable versatility of this multifunctional protein and its central role in regulating the activation and lifetime of visual transduction.

  19. Dual role for membrane localization in yeast MAP kinase cascade activation and its contribution to signaling fidelity.

    PubMed

    Lamson, Rachel E; Takahashi, Satoe; Winters, Matthew J; Pryciak, Peter M

    2006-03-21

    Distinct MAP kinase pathways in yeast share several signaling components , including the PAK Ste20 and the MAPKKK Ste11, yet signaling is specific. Mating pheromones trigger an initial step in which Ste20 activates Ste11 , and this requires plasma membrane recruitment of the MAP kinase cascade scaffold protein, Ste5 . Here, we demonstrate an additional role for Ste5 membrane localization. Once Ste11 is activated, signaling through the mating pathway remains minimal but is substantially amplified when Ste5 is recruited to the membrane either by the Gbetagamma dimer or by direct membrane targeting, even to internal membranes. Ste11 signaling is also amplified by Ste5 oligomerization and by a hyperactivating mutation in the Ste7 binding region of Ste5. We suggest a model in which membrane recruitment of Ste5 concentrates its binding partners and thereby amplifies signaling through the kinase cascade. We find similar behavior in the osmotically responsive HOG pathway. Remarkably, while both pheromone and hyperosmotic stimuli amplify signaling from constitutively active Ste11, the resulting signaling output remains pathway specific. These findings suggest a common mode of regulation in which pathway stimuli both initiate and amplify MAP kinase cascade signaling. The regulation of rate-limiting steps that lie after a branchpoint from shared components helps ensure signaling specificity.

  20. Proinflammatory signaling regulates hematopoietic stem cell emergence

    PubMed Central

    Espín-Palazón, Raquel; Stachura, David L.; Campbell, Clyde A.; García-Moreno, Diana; Cid, Natasha Del; Kim, Albert D.; Candel, Sergio; Meseguer, José; Mulero, Victoriano; Traver, David

    2014-01-01

    Summary Hematopoietic stem cells (HSCs) underlie the production of blood and immune cells for the lifetime of an organism. In vertebrate embryos, HSCs arise from the unique transdifferentiation of hemogenic endothelium comprising the floor of the dorsal aorta during a brief developmental window. To date, this process has not been replicated in vitro from pluripotent precursors, partly because the full complement of required signaling inputs remains to be determined. Here, we show that TNFR2 via TNFα activates the Notch and NF-κB signaling pathways to establish HSC fate, indicating a requirement for inflammatory signaling in HSC generation. We determine that primitive neutrophils are the major source of TNFα, assigning a role for transient innate immune cells in establishing the HSC program. These results demonstrate that proinflammatory signaling, in the absence of infection, is utilized by the developing embryo to generate the lineal precursors of the adult hematopoietic system. PMID:25416946

  1. Regulation of cholesterol biosynthesis and cancer signaling

    PubMed Central

    Gorin, Andrey; Gabitova, Linara; Astsaturov, Igor

    2012-01-01

    Cellular growth is highly dependent on sustained production of lipids. Sterol composition of cellular membranes determines multiple biochemical and biophysical properties of membrane-based processes including vesicle traffic, receptor signaling and assembly of protein complexes. Lipid biogenesis has become an attractive biochemical target in cancer given the high level of dependency on sterols and lipids in a cancer cell. This review summarized the current knowledge of mechanisms of interaction between the metabolism of sterols and receptor signaling. PMID:22824431

  2. Proteomic and functional genomic landscape of receptor tyrosine kinase and ras to extracellular signal-regulated kinase signaling.

    PubMed

    Friedman, Adam A; Tucker, George; Singh, Rohit; Yan, Dong; Vinayagam, Arunachalam; Hu, Yanhui; Binari, Richard; Hong, Pengyu; Sun, Xiaoyun; Porto, Maura; Pacifico, Svetlana; Murali, Thilakam; Finley, Russell L; Asara, John M; Berger, Bonnie; Perrimon, Norbert

    2011-10-25

    Characterizing the extent and logic of signaling networks is essential to understanding specificity in such physiological and pathophysiological contexts as cell fate decisions and mechanisms of oncogenesis and resistance to chemotherapy. Cell-based RNA interference (RNAi) screens enable the inference of large numbers of genes that regulate signaling pathways, but these screens cannot provide network structure directly. We describe an integrated network around the canonical receptor tyrosine kinase (RTK)-Ras-extracellular signal-regulated kinase (ERK) signaling pathway, generated by combining parallel genome-wide RNAi screens with protein-protein interaction (PPI) mapping by tandem affinity purification-mass spectrometry. We found that only a small fraction of the total number of PPI or RNAi screen hits was isolated under all conditions tested and that most of these represented the known canonical pathway components, suggesting that much of the core canonical ERK pathway is known. Because most of the newly identified regulators are likely cell type- and RTK-specific, our analysis provides a resource for understanding how output through this clinically relevant pathway is regulated in different contexts. We report in vivo roles for several of the previously unknown regulators, including CG10289 and PpV, the Drosophila orthologs of two components of the serine/threonine-protein phosphatase 6 complex; the Drosophila ortholog of TepIV, a glycophosphatidylinositol-linked protein mutated in human cancers; CG6453, a noncatalytic subunit of glucosidase II; and Rtf1, a histone methyltransferase.

  3. Mapping technological and biophysical capacities of watersheds to regulate floods

    USGS Publications Warehouse

    Mogollon, Beatriz; Villamagna, Amy M.; Frimpong, Emmanuel A.; Angermeier, Paul

    2016-01-01

    Flood regulation is a widely valued and studied service provided by watersheds. Flood regulation benefits people directly by decreasing the socio-economic costs of flooding and indirectly by its positive impacts on cultural (e.g., fishing) and provisioning (e.g., water supply) ecosystem services. Like other regulating ecosystem services (e.g., pollination, water purification), flood regulation is often enhanced or replaced by technology, but the relative efficacy of natural versus technological features in controlling floods has scarcely been examined. In an effort to assess flood regulation capacity for selected urban watersheds in the southeastern United States, we: (1) used long-term flood records to assess relative influence of technological and biophysical indicators on flood magnitude and duration, (2) compared the widely used runoff curve number (RCN) approach for assessing the biophysical capacity to regulate floods to an alternative approach that acknowledges land cover and soil properties separately, and (3) mapped technological and biophysical flood regulation capacities based on indicator importance-values derived for flood magnitude and duration. We found that watersheds with high biophysical (via the alternative approach) and technological capacities lengthened the duration and lowered the peak of floods. We found the RCN approach yielded results opposite that expected, possibly because it confounds soil and land cover processes, particularly in urban landscapes, while our alternative approach coherently separates these processes. Mapping biophysical (via the alternative approach) and technological capacities revealed great differences among watersheds. Our study improves on previous mapping of flood regulation by (1) incorporating technological capacity, (2) providing high spatial resolution (i.e., 10-m pixel) maps of watershed capacities, and (3) deriving importance-values for selected landscape indicators. By accounting for technology that enhances

  4. A Pivotal Role of DELLAs in Regulating Multiple Hormone Signals.

    PubMed

    Davière, Jean-Michel; Achard, Patrick

    2016-01-01

    Plant phenotypic plasticity is controlled by diverse hormone pathways, which integrate and convey information from multiple developmental and environmental signals. Moreover, in plants many processes such as growth, development, and defense are regulated in similar ways by multiple hormones. Among them, gibberellins (GAs) are phytohormones with pleiotropic actions, regulating various growth processes throughout the plant life cycle. Previous work has revealed extensive interplay between GAs and other hormones, but the molecular mechanism became apparent only recently. Molecular and physiological studies have demonstrated that DELLA proteins, considered as master negative regulators of GA signaling, integrate multiple hormone signaling pathways through physical interactions with transcription factors or regulatory proteins from different families. In this review, we summarize the latest progress in GA signaling and its direct crosstalk with the main phytohormone signaling, emphasizing the multifaceted role of DELLA proteins with key components of major hormone signaling pathways.

  5. 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

  6. Neurotrophin signaling endosomes: biogenesis, regulation, and functions.

    PubMed

    Yamashita, Naoya; Kuruvilla, Rejji

    2016-08-01

    In the nervous system, communication between neurons and their post-synaptic target cells is critical for the formation, refinement and maintenance of functional neuronal connections. Diffusible signals secreted by target tissues, exemplified by the family of neurotrophins, impinge on nerve terminals to influence diverse developmental events including neuronal survival and axonal growth. Key mechanisms of action of target-derived neurotrophins include the cell biological processes of endocytosis and retrograde trafficking of their Trk receptors from growth cones to cell bodies. In this review, we summarize the molecular mechanisms underlying this endosome-mediated signaling, focusing on the instructive role of neurotrophin signaling itself in directing its own trafficking. Recent studies have linked impaired neurotrophin trafficking to neurodevelopmental disorders, highlighting the relevance of neurotrophin endosomes in human health. PMID:27327126

  7. Role of regulator of G protein signaling proteins in bone

    PubMed Central

    Keinan, David; Yang, Shuying; Cohen, Robert E.; Yuan, Xue; Liu, Tongjun; Li, Yi-Ping

    2014-01-01

    Regulators of G protein signaling (RGS) proteins are a family with more than 30 proteins that all contain an RGS domain. In the past decade, increasing evidence has indicated that RGS proteins play crucial roles in the regulation of G protein coupling receptors (GPCR), G proteins, and calcium signaling during cell proliferation, migration, and differentiation in a variety of tissues. In bone, those proteins modulate bone development and remodeling by influencing various signaling pathways such as GPCR-G protein signaling, Wnt, calcium oscillations and PTH. This review summarizes the recent advances in the understanding of the regulation of RGS genes expression, as well as the functions and mechanisms of RGS proteins, especially in regulating GPCR-G protein signaling, Wnt signaling, calcium oscillations signaling and PTH signaling during bone development and remodeling. This review also highlights the regulation of different RGS proteins in osteoblasts, chondrocytes and osteoclasts. The knowledge from the recent advances of RGS study summarized in the review would provide the insights into new therapies for bone diseases. PMID:24389209

  8. TGF-β activates Erk MAP kinase signalling through direct phosphorylation of ShcA

    PubMed Central

    Lee, Matt K; Pardoux, Cécile; Hall, Marie C; Lee, Pierre S; Warburton, David; Qing, Jing; Smith, Susan M; Derynck, Rik

    2007-01-01

    Erk1/Erk2 MAP kinases are key regulators of cell behaviour and their activation is generally associated with tyrosine kinase signalling. However, TGF-β stimulation also activates Erk MAP kinases through an undefined mechanism, albeit to a much lower level than receptor tyrosine kinase stimulation. We report that upon TGF-β stimulation, the activated TGF-β type I receptor (TβRI) recruits and directly phosphorylates ShcA proteins on tyrosine and serine. This dual phosphorylation results from an intrinsic TβRI tyrosine kinase activity that complements its well-defined serine-threonine kinase function. TGF-β-induced ShcA phosphorylation induces ShcA association with Grb2 and Sos, thereby initiating the well-characterised pathway linking receptor tyrosine kinases with Erk MAP kinases. We also found that TβRI is tyrosine phosphorylated in response to TGF-β. Thus, TβRI, like the TGF-β type II receptor, is a dual-specificity kinase. Recruitment of tyrosine kinase signalling pathways may account for aspects of TGF-β biology that are independent of Smad signalling. PMID:17673906

  9. Spectrin regulates Hippo signaling by modulating cortical actomyosin activity

    PubMed Central

    Deng, Hua; Wang, Wei; Yu, Jianzhong; Zheng, Yonggang; Qing, Yun; Pan, Duojia

    2015-01-01

    The Hippo pathway controls tissue growth through a core kinase cascade that impinges on the transcription of growth-regulatory genes. Understanding how this pathway is regulated in development remains a major challenge. Recent studies suggested that Hippo signaling can be modulated by cytoskeletal tension through a Rok-myosin II pathway. How cytoskeletal tension is regulated or its relationship to the other known upstream regulators of the Hippo pathway remains poorly defined. In this study, we identify spectrin, a contractile protein at the cytoskeleton-membrane interface, as an upstream regulator of the Hippo signaling pathway. We show that, in contrast to canonical upstream regulators such as Crumbs, Kibra, Expanded, and Merlin, spectrin regulates Hippo signaling in a distinct way by modulating cortical actomyosin activity through non-muscle myosin II. These results uncover an essential mediator of Hippo signaling by cytoskeleton tension, providing a new entry point to dissecting how mechanical signals regulate Hippo signaling in living tissues. DOI: http://dx.doi.org/10.7554/eLife.06567.001 PMID:25826608

  10. Signal regulators of systemic acquired resistance

    PubMed Central

    Gao, Qing-Ming; Zhu, Shifeng; Kachroo, Pradeep; Kachroo, Aardra

    2015-01-01

    Salicylic acid (SA) is an important phytohormone that plays a vital role in a number of physiological responses, including plant defense. The last two decades have witnessed a number of breakthroughs related to biosynthesis, transport, perception and signaling mediated by SA. These findings demonstrate that SA plays a crictical role in both local and systemic defense responses. Systemic acquired resistance (SAR) is one such SA-dependent response. SAR is a long distance signaling mechanism that provides broad spectrum and long-lasting resistance to secondary infections throughout the plant. This unique feature makes SAR a highly desirable trait in crop production. This review summarizes the recent advances in the role of SA in SAR and discusses its relationship to other SAR inducers. PMID:25918514

  11. Roles for Regulator of G Protein Signaling Proteins in Synaptic Signaling and Plasticity.

    PubMed

    Gerber, Kyle J; Squires, Katherine E; Hepler, John R

    2016-02-01

    The regulator of G protein signaling (RGS) family of proteins serves critical roles in G protein-coupled receptor (GPCR) and heterotrimeric G protein signal transduction. RGS proteins are best understood as negative regulators of GPCR/G protein signaling. They achieve this by acting as GTPase activating proteins (GAPs) for Gα subunits and accelerating the turnoff of G protein signaling. Many RGS proteins also bind additional signaling partners that either regulate their functions or enable them to regulate other important signaling events. At neuronal synapses, GPCRs, G proteins, and RGS proteins work in coordination to regulate key aspects of neurotransmitter release, synaptic transmission, and synaptic plasticity, which are necessary for central nervous system physiology and behavior. Accumulating evidence has revealed key roles for specific RGS proteins in multiple signaling pathways at neuronal synapses, regulating both pre- and postsynaptic signaling events and synaptic plasticity. Here, we review and highlight the current knowledge of specific RGS proteins (RGS2, RGS4, RGS7, RGS9-2, and RGS14) that have been clearly demonstrated to serve critical roles in modulating synaptic signaling and plasticity throughout the brain, and we consider their potential as future therapeutic targets.

  12. Knowing when to grow: signals regulating bud dormancy.

    PubMed

    Horvath, David P; Anderson, James V; Chao, Wun S; Foley, Michael E

    2003-11-01

    Dormancy regulation in vegetative buds is a complex process necessary for plant survival, development and architecture. Our understanding of and ability to manipulate these processes are crucial for increasing the yield and availability of much of the world's food. In many cases, release of dormancy results in increased cell division and changes in developmental programs. Much can be learned about dormancy regulation by identifying interactions of signals in these crucial processes. Internal signals such as hormones and sugar, and external signals such as light act through specific, overlapping signal transduction pathways to regulate endo-, eco- and paradormancy. Epigenetic-like regulation of endodormancy suggests a possible role for chromatin remodeling similar to that known for the vernalization responses during flowering.

  13. Overlapping functions of the MAP4K family kinases Hppy and Msn in Hippo signaling

    PubMed Central

    Li, Shuangxi; Cho, Yong Suk; Yue, Tao; Ip, Y Tony; Jiang, Jin

    2015-01-01

    The Hippo (Hpo) tumor suppressor pathway is an evolutionarily conserved signaling pathway that controls tissue growth and organ size in species ranging from Drosophila to human, and its malfunction has been implicated in many types of human cancer. In this study, we conducted a kinome screen and identified Happyhour (Hppy)/MAP4K3 as a novel player in the Hpo pathway. Our biochemical study showed that Hppy binds and phosphorylates Wts. Our genetic experiments suggest that Hppy acts in parallel and partial redundantly with Misshapen (Msn)/MAP4K4 to regulate Yki nuclear localization and Hpo target gene expression in Drosophila wing imaginal discs. Furthermore, we showed that cytoskeleton stress restricts Yki nuclear localization through Hppy and Msn when Hpo activity is compromised, thus providing an explanation for the Wts-dependent but Hpo-independent regulation of Yki in certain contexts. Our study has unraveled an additional layer of complexity in the Hpo signaling pathway and laid down a foundation for exploring how different upstream regulators feed into the core Hpo pathway. PMID:27462435

  14. Regulation of Wnt/β-Catenin Signaling by Protein Kinases

    PubMed Central

    Verheyen, Esther M.; Gottardi, Cara J.

    2011-01-01

    The Wnt/β-catenin signaling pathway plays essential roles during development and adult tissue homeostasis. Inappropriate activation of the pathway can result in a variety of malignancies. Protein kinases have emerged as key regulators at multiple steps of the Wnt pathway. In this review, we present a synthesis covering the latest information on how Wnt signaling is regulated by diverse protein kinases. PMID:19623618

  15. Functional mapping of reaction norms to multiple environmental signals.

    PubMed

    Wu, Jiasheng; Zeng, Yanru; Huang, Jianqing; Hou, Wei; Zhu, Jun; Wu, Rongling

    2007-02-01

    Whether there are different genes involved in response to different environmental signals and how these genes interact to determine the final expression of the trait are of fundamental importance in agricultural and biological research. We present a statistical framework for mapping environment-induced genes (or quantitative trait loci, QTLs) of major effects on the expression of a trait that respond to changing environments. This framework is constructed with a maximum-likelihood-based mixture model, in which the mean and covariance structure of environment-induced responses is modelled. The means for responses to continuous environmental states, referred to as reaction norms, are approximated for different QTL genotypes by mathematical equations that were derived from fundamental biological principles or based on statistical goodness-of-fit to observational data. The residual covariance between different environmental states was modelled by autoregressive processes. Such an approach to studying the genetic control of reaction norms can be expected to be advantageous over traditional mapping approaches in which no biological principles and statistical structures are considered. We demonstrate the analytical procedure and power of this approach by modelling the photosynthetic rate process as a function of temperature and light irradiance. Our approach allows for testing how a QTL affects the reaction norm of photosynthetic rate to a specific environment and whether there exist different QTLs to mediate photosynthetic responses to temperature and light irradiance, respectively. PMID:17517157

  16. IAPs: Modular regulators of cell signalling.

    PubMed

    Budhidarmo, Rhesa; Day, Catherine L

    2015-03-01

    Members of the inhibitor of apoptosis (IAP) family are characterised by the presence of at least one baculoviral IAP repeat (BIR) domain. However, during the course of evolution, other globular modules have been adopted to perform distinct functions. Consequently, the IAP family is now recognised as consisting of members that perform critical functions in different aspects of cellular regulation. In this review, the structural diversity present within the IAP protein family is presented. Known structures of individual domains are discussed and their properties are described in light of recent data. In particular the plasticity of BIR domains and their ability to accommodate different binding partners is highlighted, as well as the importance of communication between the domains in regulating the covalent attachment of ubiquitin.

  17. rMAPS: RNA map analysis and plotting server for alternative exon regulation

    PubMed Central

    Park, Juw Won; Jung, Sungbo; Rouchka, Eric C.; Tseng, Yu-Ting; Xing, Yi

    2016-01-01

    RNA-binding proteins (RBPs) play a critical role in the regulation of alternative splicing (AS), a prevalent mechanism for generating transcriptomic and proteomic diversity in eukaryotic cells. Studies have shown that AS can be regulated by RBPs in a binding-site-position dependent manner. Depending on where RBPs bind, splicing of an alternative exon can be enhanced or suppressed. Therefore, spatial analyses of RBP motifs and binding sites around alternative exons will help elucidate splicing regulation by RBPs. The development of high-throughput sequencing technologies has allowed transcriptome-wide analyses of AS and RBP–RNA interactions. Given a set of differentially regulated alternative exons obtained from RNA sequencing (RNA-seq) experiments, the rMAPS web server (http://rmaps.cecsresearch.org) performs motif analyses of RBPs in the vicinity of alternatively spliced exons and creates RNA maps that depict the spatial patterns of RBP motifs. Similarly, rMAPS can also perform spatial analyses of RBP–RNA binding sites identified by cross-linking immunoprecipitation sequencing (CLIP-seq) experiments. We anticipate rMAPS will be a useful tool for elucidating RBP regulation of alternative exon splicing using high-throughput sequencing data. PMID:27174931

  18. From tyrosine to melanin: Signaling pathways and factors regulating melanogenesis.

    PubMed

    Rzepka, Zuzanna; Buszman, Ewa; Beberok, Artur; Wrześniok, Dorota

    2016-01-01

    Melanins are natural pigments of skin, hair and eyes and can be classified into two main types: brown to black eumelanin and yellow to reddish-brown pheomelanin. Biosynthesis of melanins takes place in melanosomes, which are specialized cytoplasmic organelles of melanocytes - dendritic cells located in the basal layer of the epidermis, uveal tract of the eye, hair follicles, as well as in the inner ear, central nervous system and heart. Melanogenesis is a multistep process and begins with the conversion of amino acid L-tyrosine to DOPAquinone. The addition of cysteine or glutathione to DOPAquinone leads to the intermediates formation, followed by subsequent transformations and polymerization to the final product, pheomelanin. In the absence of thiol compounds DOPAquinone undergoes an intramolecular cyclization and oxidation to form DOPAchrome, which is then converted to 5,6-dihydroksyindole (DHI) or 5,6-dihydroxyindole-2-carboxylic acid (DHICA). Eumelanin is formed by polymerization of DHI and DHICA and their quinones. Regulation of melanogenesis is achieved by physical and biochemical factors. The article presents the intracellular signaling pathways: cAMP/PKA/CREB/MITF cascade, MAP kinases cascade, PLC/DAG/PKCβ cascade and NO/cGMP/PKG cascade, which are involved in the regulation of expression and activity of the melanogenesis-related proteins by ultraviolet radiation and endogenous agents (cytokines, hormones). Activity of the key melanogenic enzyme, tyrosinase, is also affected by pH and temperature. Many pharmacologically active substances are able to inhibit or stimulate melanin biosynthesis, as evidenced by in vitro studies on cultured pigment cells. PMID:27356601

  19. Phosphatase and Tensin Homologue: Novel Regulation by Developmental Signaling

    PubMed Central

    Jerde, Travis J.

    2015-01-01

    Phosphatase and tensin homologue (PTEN) is a critical cell endogenous inhibitor of phosphoinositide signaling in mammalian cells. PTEN dephosphorylates phosphoinositide trisphosphate (PIP3), and by so doing PTEN has the function of negative regulation of Akt, thereby inhibiting this key intracellular signal transduction pathway. In numerous cell types, PTEN loss-of-function mutations result in unopposed Akt signaling, producing numerous effects on cells. Numerous reports exist regarding mutations in PTEN leading to unregulated Akt and human disease, most notably cancer. However, less is commonly known about nonmutational regulation of PTEN. This review focuses on an emerging literature on the regulation of PTEN at the transcriptional, posttranscriptional, translational, and posttranslational levels. Specifically, a focus is placed on the role developmental signaling pathways play in PTEN regulation; this includes insulin-like growth factor, NOTCH, transforming growth factor, bone morphogenetic protein, wnt, and hedgehog signaling. The regulation of PTEN by developmental mediators affects critical biological processes including neuronal and organ development, stem cell maintenance, cell cycle regulation, inflammation, response to hypoxia, repair and recovery, and cell death and survival. Perturbations of PTEN regulation consequently lead to human diseases such as cancer, chronic inflammatory syndromes, developmental abnormalities, diabetes, and neurodegeneration. PMID:26339505

  20. Develop advanced nonlinear signal analysis topographical mapping system

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The Space Shuttle Main Engine (SSME) has been undergoing extensive flight certification and developmental testing, which involves some 250 health monitoring measurements. Under the severe temperature, pressure, and dynamic environments sustained during operation, numerous major component failures have occurred, resulting in extensive engine hardware damage and scheduling losses. To enhance SSME safety and reliability, detailed analysis and evaluation of the measurements signal are mandatory to assess its dynamic characteristics and operational condition. Efficient and reliable signal detection techniques will reduce catastrophic system failure risks and expedite the evaluation of both flight and ground test data, and thereby reduce launch turn-around time. The basic objective of this contract are threefold: (1) develop and validate a hierarchy of innovative signal analysis techniques for nonlinear and nonstationary time-frequency analysis. Performance evaluation will be carried out through detailed analysis of extensive SSME static firing and flight data. These techniques will be incorporated into a fully automated system; (2) develop an advanced nonlinear signal analysis topographical mapping system (ATMS) to generate a Compressed SSME TOPO Data Base (CSTDB). This ATMS system will convert tremendous amount of complex vibration signals from the entire SSME test history into a bank of succinct image-like patterns while retaining all respective phase information. High compression ratio can be achieved to allow minimal storage requirement, while providing fast signature retrieval, pattern comparison, and identification capabilities; and (3) integrate the nonlinear correlation techniques into the CSTDB data base with compatible TOPO input data format. Such integrated ATMS system will provide the large test archives necessary for quick signature comparison. This study will provide timely assessment of SSME component operational status, identify probable causes of

  1. Develop advanced nonlinear signal analysis topographical mapping system

    NASA Technical Reports Server (NTRS)

    Jong, Jen-Yi

    1993-01-01

    The SSME has been undergoing extensive flight certification and developmental testing, which involves some 250 health monitoring measurements. Under the severe temperature pressure, and dynamic environments sustained during operation, numerous major component failures have occurred, resulting in extensive engine hardware damage and scheduling losses. To enhance SSME safety and reliability, detailed analysis and evaluation of the measurements signal are mandatory to assess its dynamic characteristics and operational condition. Efficient and reliable signal detection techniques will reduce catastrophic system failure risks and expedite the evaluation of both flight and ground test data, and thereby reduce launch turn-around time. The basic objective of this contract are threefold: (1) Develop and validate a hierarchy of innovative signal analysis techniques for nonlinear and nonstationary time-frequency analysis. Performance evaluation will be carried out through detailed analysis of extensive SSME static firing and flight data. These techniques will be incorporated into a fully automated system. (2) Develop an advanced nonlinear signal analysis topographical mapping system (ATMS) to generate a Compressed SSME TOPO Data Base (CSTDB). This ATMS system will convert tremendous amounts of complex vibration signals from the entire SSME test history into a bank of succinct image-like patterns while retaining all respective phase information. A high compression ratio can be achieved to allow the minimal storage requirement, while providing fast signature retrieval, pattern comparison, and identification capabilities. (3) Integrate the nonlinear correlation techniques into the CSTDB data base with compatible TOPO input data format. Such integrated ATMS system will provide the large test archives necessary for a quick signature comparison. This study will provide timely assessment of SSME component operational status, identify probable causes of malfunction, and indicate

  2. Regulation of insect behavior via the insulin-signaling pathway

    PubMed Central

    Erion, Renske; Sehgal, Amita

    2013-01-01

    The insulin/insulin-like growth factor signaling (IIS) pathway is well-established as a critical regulator of growth and metabolic homeostasis across the animal kingdom. Insulin-like peptides (ILPs), the functional analogs of mammalian insulin, were initially discovered in the silkmoth Bombyx mori and subsequently identified in many other insect species. Initial research focused on the role of insulin signaling in metabolism, cell proliferation, development, reproduction and aging. More recently however, increasing attention has been given to the role of insulin in the regulation of neuronal function and behavior. Here we review the role of insulin signaling in two specific insect behaviors: feeding and locomotion. PMID:24348428

  3. Regulation of Hedgehog Signalling Inside and Outside the Cell

    PubMed Central

    Ramsbottom, Simon A.; Pownall, Mary E.

    2016-01-01

    The hedgehog (Hh) signalling pathway is conserved throughout metazoans and plays an important regulatory role in both embryonic development and adult homeostasis. Many levels of regulation exist that control the release, reception, and interpretation of the hedgehog signal. The fatty nature of the Shh ligand means that it tends to associate tightly with the cell membrane, and yet it is known to act as a morphogen that diffuses to elicit pattern formation. Heparan sulfate proteoglycans (HSPGs) play a major role in the regulation of Hh distribution outside the cell. Inside the cell, the primary cilium provides an important hub for processing the Hh signal in vertebrates. This review will summarise the current understanding of how the Hh pathway is regulated from ligand production, release, and diffusion, through to signal reception and intracellular transduction. PMID:27547735

  4. Aberrant regulation of Wnt signaling in hepatocellular carcinoma

    PubMed Central

    Liu, Li-Juan; Xie, Shui-Xiang; Chen, Ya-Tang; Xue, Jing-Ling; Zhang, Chuan-Jie; Zhu, Fan

    2016-01-01

    Hepatocellular carcinoma (HCC) is one of the most lethal malignancies in the world. Several signaling pathways, including the wingless/int-1 (Wnt) signaling pathway, have been shown to be commonly activated in HCC. The Wnt signaling pathway can be triggered via both catenin β1 (CTNNB1)-dependent (also known as “canonical”) and CTNNB1-independent (often referred to as “non-canonical”) pathways. Specifically, the canonical Wnt pathway is one of those most frequently reported in HCC. Aberrant regulation from three complexes (the cell-surface receptor complex, the cytoplasmic destruction complex and the nuclear CTNNB1/T-cell-specific transcription factor/lymphoid enhancer binding factor transcriptional complex) are all involved in HCC. Although the non-canonical Wnt pathway is rarely reported, two main non-canonical pathways, Wnt/planar cell polarity pathway and Wnt/Ca2+ pathway, participate in the regulation of hepatocarcinogenesis. Interestingly, the canonical Wnt pathway is antagonized by non-canonical Wnt signaling in HCC. Moreover, other signaling cascades have also been demonstrated to regulate the Wnt pathway through crosstalk in HCC pathogenesis. This review provides a perspective on the emerging evidence that the aberrant regulation of Wnt signaling is a critical mechanism for the development of HCC. Furthermore, crosstalk between different signaling pathways might be conducive to the development of novel molecular targets of HCC. PMID:27672271

  5. Regulation of Bone Morphogenetic Protein Signaling by ADP-ribosylation*

    PubMed Central

    Watanabe, Yukihide; Papoutsoglou, Panagiotis; Maturi, Varun; Tsubakihara, Yutaro; Hottiger, Michael O.; Heldin, Carl-Henrik; Moustakas, Aristidis

    2016-01-01

    We previously established a mechanism of negative regulation of transforming growth factor β signaling mediated by the nuclear ADP-ribosylating enzyme poly-(ADP-ribose) polymerase 1 (PARP1) and the deribosylating enzyme poly-(ADP-ribose) glycohydrolase (PARG), which dynamically regulate ADP-ribosylation of Smad3 and Smad4, two central signaling proteins of the pathway. Here we demonstrate that the bone morphogenetic protein (BMP) pathway can also be regulated by the opposing actions of PARP1 and PARG. PARG positively contributes to BMP signaling and forms physical complexes with Smad5 and Smad4. The positive role PARG plays during BMP signaling can be neutralized by PARP1, as demonstrated by experiments where PARG and PARP1 are simultaneously silenced. In contrast to PARG, ectopic expression of PARP1 suppresses BMP signaling, whereas silencing of endogenous PARP1 enhances signaling and BMP-induced differentiation. The two major Smad proteins of the BMP pathway, Smad1 and Smad5, interact with PARP1 and can be ADP-ribosylated in vitro, whereas PARG causes deribosylation. The overall outcome of this mode of regulation of BMP signal transduction provides a fine-tuning mechanism based on the two major enzymes that control cellular ADP-ribosylation. PMID:27129221

  6. Aberrant regulation of Wnt signaling in hepatocellular carcinoma.

    PubMed

    Liu, Li-Juan; Xie, Shui-Xiang; Chen, Ya-Tang; Xue, Jing-Ling; Zhang, Chuan-Jie; Zhu, Fan

    2016-09-01

    Hepatocellular carcinoma (HCC) is one of the most lethal malignancies in the world. Several signaling pathways, including the wingless/int-1 (Wnt) signaling pathway, have been shown to be commonly activated in HCC. The Wnt signaling pathway can be triggered via both catenin β1 (CTNNB1)-dependent (also known as "canonical") and CTNNB1-independent (often referred to as "non-canonical") pathways. Specifically, the canonical Wnt pathway is one of those most frequently reported in HCC. Aberrant regulation from three complexes (the cell-surface receptor complex, the cytoplasmic destruction complex and the nuclear CTNNB1/T-cell-specific transcription factor/lymphoid enhancer binding factor transcriptional complex) are all involved in HCC. Although the non-canonical Wnt pathway is rarely reported, two main non-canonical pathways, Wnt/planar cell polarity pathway and Wnt/Ca(2+) pathway, participate in the regulation of hepatocarcinogenesis. Interestingly, the canonical Wnt pathway is antagonized by non-canonical Wnt signaling in HCC. Moreover, other signaling cascades have also been demonstrated to regulate the Wnt pathway through crosstalk in HCC pathogenesis. This review provides a perspective on the emerging evidence that the aberrant regulation of Wnt signaling is a critical mechanism for the development of HCC. Furthermore, crosstalk between different signaling pathways might be conducive to the development of novel molecular targets of HCC. PMID:27672271

  7. Aberrant regulation of Wnt signaling in hepatocellular carcinoma

    PubMed Central

    Liu, Li-Juan; Xie, Shui-Xiang; Chen, Ya-Tang; Xue, Jing-Ling; Zhang, Chuan-Jie; Zhu, Fan

    2016-01-01

    Hepatocellular carcinoma (HCC) is one of the most lethal malignancies in the world. Several signaling pathways, including the wingless/int-1 (Wnt) signaling pathway, have been shown to be commonly activated in HCC. The Wnt signaling pathway can be triggered via both catenin β1 (CTNNB1)-dependent (also known as “canonical”) and CTNNB1-independent (often referred to as “non-canonical”) pathways. Specifically, the canonical Wnt pathway is one of those most frequently reported in HCC. Aberrant regulation from three complexes (the cell-surface receptor complex, the cytoplasmic destruction complex and the nuclear CTNNB1/T-cell-specific transcription factor/lymphoid enhancer binding factor transcriptional complex) are all involved in HCC. Although the non-canonical Wnt pathway is rarely reported, two main non-canonical pathways, Wnt/planar cell polarity pathway and Wnt/Ca2+ pathway, participate in the regulation of hepatocarcinogenesis. Interestingly, the canonical Wnt pathway is antagonized by non-canonical Wnt signaling in HCC. Moreover, other signaling cascades have also been demonstrated to regulate the Wnt pathway through crosstalk in HCC pathogenesis. This review provides a perspective on the emerging evidence that the aberrant regulation of Wnt signaling is a critical mechanism for the development of HCC. Furthermore, crosstalk between different signaling pathways might be conducive to the development of novel molecular targets of HCC.

  8. Feedback Regulation of Kinase Signaling Pathways by AREs and GREs

    PubMed Central

    Vlasova-St. Louis, Irina; Bohjanen, Paul R.

    2016-01-01

    In response to environmental signals, kinases phosphorylate numerous proteins, including RNA-binding proteins such as the AU-rich element (ARE) binding proteins, and the GU-rich element (GRE) binding proteins. Posttranslational modifications of these proteins lead to a significant changes in the abundance of target mRNAs, and affect gene expression during cellular activation, proliferation, and stress responses. In this review, we summarize the effect of phosphorylation on the function of ARE-binding proteins ZFP36 and ELAVL1 and the GRE-binding protein CELF1. The networks of target mRNAs that these proteins bind and regulate include transcripts encoding kinases and kinase signaling pathways (KSP) components. Thus, kinase signaling pathways are involved in feedback regulation, whereby kinases regulate RNA-binding proteins that subsequently regulate mRNA stability of ARE- or GRE-containing transcripts that encode components of KSP. PMID:26821046

  9. Oscillatory Dynamics of the Extracellular Signal-regulated Kinase Pathway

    SciTech Connect

    Shankaran, Harish; Wiley, H. S.

    2010-12-01

    The extracellular signal-regulated kinase (ERK) pathway is a central signaling pathway in development and disease and is regulated by multiple negative and positive feedback loops. Recent studies have shown negative feedback from ERK to upstream regulators can give rise to biochemical oscillations with a periodicity of between 15-30 minutes. Feedback due to the stimulated transcription of negative regulators of the ERK pathway can also give rise to transcriptional oscillations with a periodicity of 1-2h. The biological significance of these oscillations is not clear, but recent evidence suggests that transcriptional oscillations participate in developmental processes, such as somite formation. Biochemical oscillations are more enigmatic, but could provide a mechanism for encoding different types of inputs into a common signaling pathway.

  10. Signal Transduction Pathways that Regulate CAB Gene Expression

    SciTech Connect

    Chory, Joanne

    2004-12-31

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

  11. Signal Transduction Pathways that Regulate CAB Gene Expression

    SciTech Connect

    Chory, Joanne

    2006-01-16

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

  12. REGULATION OF EPHRIN-A EXPRESSION IN COMPRESSED RETINOCOLLICULAR MAPS

    PubMed Central

    Tadesse, T.; Cheng, Q.; Xu, M.; Baro, D.J.; Young, L.J.; Pallas, S.L.

    2012-01-01

    Retinotopic maps can undergo compression and expansion in response to changes in target size, but the mechanism underlying this compensatory process has remained a mystery. The discovery of ephrins as molecular mediators of Sperry’s chemoaffinity process allows a mechanistic approach to this important issue. In Syrian hamsters, neonatal, partial (PT) ablation of posterior superior colliculus (SC) leads to compression of the retinotopic map, independent of neural activity. Graded, repulsive EphA receptor/ephrin-A ligand interactions direct the formation of the retinocollicular map, but whether ephrins might also be involved in map compression is unknown. To examine whether map compression might be directed by changes in the ephrin expression pattern, we compared ephrin-A2 and ephrin-A5 mRNA expression between normal SC and PT SC using in situ hybridization and quantitative real-time PCR. We found that ephrin-A ligand expression in the compressed maps was low anteriorly and high posteriorly, as in normal animals. Consistent with our hypothesis, the steepness of the ephrin gradient increased in the lesioned colliculi. Interestingly, overall levels of ephrin-A2 and -A5 expression declined immediately after neonatal target damage, perhaps promoting axon outgrowth. These data establish a correlation between changes in ephrin-A gradients and map compression, and suggest that ephrin-A expression gradients may be regulated by target size. This in turn could lead to compression of the retinocollicular map onto the reduced target. These findings have important implications for mechanisms of recovery from traumatic brain injury. PMID:23008269

  13. The roles of signaling pathways in regulating kidney development.

    PubMed

    Xiao, Qiu; Rongfei, Wei; Lingqiang, Zhang; Fuchu, He

    2015-01-01

    The development of mammalian kidney is a complex process. The reciprocal inductive interactions between epithelial cells and metanephric mesenchymal cells determine cell fates including proliferation, growth, apoptosis, and eventually contribute to the formation of an intact kidney. Multiple signaling pathways, including the GDNF/Ret, Wnt and BMP signaling pathways, have been shown to regulate the development of kidney. A myriad of signaling pathways and their cross-talks form a precise spatiotemporal regulatory network, which ensures the kidney to be properly organized. In this review, we summarize the physiological process of kidney development as well as the involved signaling pathways and their interplay.

  14. Regulation of spermatogonial stem cell self-renewal and spermatocyte meiosis by Sertoli cell signaling.

    PubMed

    Chen, Su-Ren; Liu, Yi-Xun

    2015-04-01

    Spermatogenesis is a continuous and productive process supported by the self-renewal and differentiation of spermatogonial stem cells (SSCs), which arise from undifferentiated precursors known as gonocytes and are strictly controlled in a special 'niche' microenvironment in the seminiferous tubules. Sertoli cells, the only somatic cell type in the tubules, directly interact with SSCs to control their proliferation and differentiation through the secretion of specific factors. Spermatocyte meiosis is another key step of spermatogenesis, which is regulated by Sertoli cells on the luminal side of the blood-testis barrier through paracrine signaling. In this review, we mainly focus on the role of Sertoli cells in the regulation of SSC self-renewal and spermatocyte meiosis, with particular emphasis on paracrine and endocrine-mediated signaling pathways. Sertoli cell growth factors, such as glial cell line-derived neurotrophic factor (GDNF) and fibroblast growth factor 2 (FGF2), as well as Sertoli cell transcription factors, such as ETS variant 5 (ERM; also known as ETV5), nociceptin, neuregulin 1 (NRG1), and androgen receptor (AR), have been identified as the most important upstream factors that regulate SSC self-renewal and spermatocyte meiosis. Other transcription factors and signaling pathways (GDNF-RET-GFRA1 signaling, FGF2-MAP2K1 signaling, CXCL12-CXCR4 signaling, CCL9-CCR1 signaling, FSH-nociceptin/OPRL1, retinoic acid/FSH-NRG/ERBB4, and AR/RB-ARID4A/ARID4B) are also addressed.

  15. VESGEN Software for Mapping and Quantification of Vascular Regulators

    NASA Technical Reports Server (NTRS)

    Parsons-Wingerter, Patricia A.; Vickerman, Mary B.; Keith, Patricia A.

    2012-01-01

    VESsel GENeration (VESGEN) Analysis is an automated software that maps and quantifies effects of vascular regulators on vascular morphology by analyzing important vessel parameters. Quantification parameters include vessel diameter, length, branch points, density, and fractal dimension. For vascular trees, measurements are reported as dependent functions of vessel branching generation. VESGEN maps and quantifies vascular morphological events according to fractal-based vascular branching generation. It also relies on careful imaging of branching and networked vascular form. It was developed as a plug-in for ImageJ (National Institutes of Health, USA). VESGEN uses image-processing concepts of 8-neighbor pixel connectivity, skeleton, and distance map to analyze 2D, black-and-white (binary) images of vascular trees, networks, and tree-network composites. VESGEN maps typically 5 to 12 (or more) generations of vascular branching, starting from a single parent vessel. These generations are tracked and measured for critical vascular parameters that include vessel diameter, length, density and number, and tortuosity per branching generation. The effects of vascular therapeutics and regulators on vascular morphology and branching tested in human clinical or laboratory animal experimental studies are quantified by comparing vascular parameters with control groups. VESGEN provides a user interface to both guide and allow control over the users vascular analysis process. An option is provided to select a morphological tissue type of vascular trees, network or tree-network composites, which determines the general collections of algorithms, intermediate images, and output images and measurements that will be produced.

  16. Signaling and transcriptional regulation in osteoblast commitment and differentiation

    PubMed Central

    Huang, Wei; Yang, Shuying; Shao, Jianzhong; Li, Yi-Ping

    2013-01-01

    The major event that triggers osteogenesis is the transition of mesenchymal stem cells into bone forming, differentiating osteoblast cells. Osteoblast differentiation is the primary component of bone formation, exemplified by the synthesis, deposition and mineralization of extracellular matrix. Although not well understood, osteoblast differentiation from mesenchymal stem cells is a well-orchestrated process. Recent advances in molecular and genetic studies using gene targeting in mouse enable a better understanding of the multiple factors and signaling networks that control the differentiation process at a molecular level. Osteoblast commitment and differentiation are controlled by complex activities involving signal transduction and transcriptional regulation of gene expression. We review Wnt signaling pathway and Runx2 regulation network, which are critical for osteoblast differentiation. Many other factors and signaling pathways have been implicated in regulation of osteoblast differentiation in a network manner, such as the factors Osterix, ATF4, and SATB2 and the TGF-beta, Hedgehog, FGF, ephrin, and sympathetic signaling pathways. This review summarizes the recent advances in the studies of signaling transduction pathways and transcriptional regulation of osteoblast cell lineage commitment and differentiation. The knowledge of osteoblast commitment and differentiation should be applied towards the development of new diagnostic and therapeutic alternatives for human bone diseases. PMID:17485283

  17. MAP kinases with distinct inhibitory functions impart signaling specificity during yeast differentiation.

    PubMed

    Madhani, H D; Styles, C A; Fink, G R

    1997-11-28

    Filamentous invasive growth of S. cerevisiae requires multiple elements of the mitogen-activated protein kinase (MAPK) signaling cascade that are also components of the mating pheromone response pathway. Here we show that, despite sharing several constituents, the two pathways use different MAP kinases. The Fus3 MAPK regulates mating, whereas the Kss1 MAPK regulates filamentation and invasion. Remarkably, in addition to their kinase-dependent activation functions, Kss1 and Fus3 each have a distinct kinase-independent inhibitory function. Kss1 inhibits the filamentation pathway by interacting with its target transcription factor Ste12. Fus3 has a different inhibitory activity that prevents the inappropriate activation of invasion by the pheromone response pathway. In the absence of Fus3, there is erroneous crosstalk in which mating pheromone now activates filamentation-specific gene expression using the Kss1 MAPK. PMID:9393860

  18. Microtubules Regulate Focal Adhesion Dynamics through MAP4K4

    PubMed Central

    Yue, Jiping; Xie, Min; Gou, Xuewen; Lee, Philbert; Schneider, Michael D; Wu, Xiaoyang

    2014-01-01

    Disassembly of focal adhesions (FAs) allows cell retraction and integrin detachment from the ECM, processes critical for cell movement. Growth of MT (microtubule) can promote FA turnover by serving as tracks to deliver proteins essential for FA disassembly. The molecular nature of this FA “disassembly factor”, however, remains elusive. By quantitative proteomics, we identified MAP4K4 (mitogen-activated protein kinase kinase kinase kinase 4) as a FA regulator that associates with MTs. Conditional knockout (cKO) of MAP4K4 in skin stabilizes FAs and impairs epidermal migration. By exploring underlying mechanisms, we further show that MAP4K4 associates with EB2, a MT binding protein, and IQSEC1, a guanine nucleotide exchange factor (GEF) specific for Arf6, whose activation promotes integrin internalization. Together, our findings provide critical insights into FA disassembly, suggesting that MTs can deliver MAP4K4 toward FAs through EB2, where MAP4K4 can in turn activate Arf6 via IQSEC1 and enhance FA dissolution. PMID:25490267

  19. Microtubules regulate focal adhesion dynamics through MAP4K4.

    PubMed

    Yue, Jiping; Xie, Min; Gou, Xuewen; Lee, Philbert; Schneider, Michael D; Wu, Xiaoyang

    2014-12-01

    Disassembly of focal adhesions (FAs) allows cell retraction and integrin detachment from the extracellular matrix, processes critical for cell movement. Growth of microtubules (MTs) can promote FA turnover by serving as tracks to deliver proteins essential for FA disassembly. The molecular nature of this FA "disassembly factor," however, remains elusive. By quantitative proteomics, we identified mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) as an FA regulator that associates with MTs. Knockout of MAP4K4 stabilizes FAs and impairs cell migration. By exploring underlying mechanisms, we further show that MAP4K4 associates with ending binding 2 (EB2) and IQ motif and SEC7 domain-containing protein 1 (IQSEC1), a guanine nucleotide exchange factor specific for Arf6, whose activation promotes integrin internalization. Together, our findings provide critical insight into FA disassembly, suggesting that MTs can deliver MAP4K4 toward FAs through EB2, where MAP4K4 can, in turn, activate Arf6 via IQSEC1 and enhance FA dissolution. PMID:25490267

  20. New Insights into How Trafficking Regulates T Cell Receptor Signaling

    PubMed Central

    Lou, Jieqiong; Rossy, Jérémie; Deng, Qiji; Pageon, Sophie V.; Gaus, Katharina

    2016-01-01

    There is emerging evidence that exocytosis plays an important role in regulating T cell receptor (TCR) signaling. The trafficking molecules involved in lytic granule (LG) secretion in cytotoxic T lymphocytes (CTL) have been well-studied due to the immune disorder known as familial hemophagocytic lymphohistiocytosis (FHLH). However, the knowledge of trafficking machineries regulating the exocytosis of receptors and signaling molecules remains quite limited. In this review, we summarize the reported trafficking molecules involved in the transport of the TCR and downstream signaling molecules to the cell surface. By combining this information with the known knowledge of LG exocytosis and general exocytic trafficking machinery, we attempt to draw a more complete picture of how the TCR signaling network and exocytic trafficking matrix are interconnected to facilitate T cell activation. This also highlights how membrane compartmentalization facilitates the spatiotemporal organization of cellular responses that are essential for immune functions. PMID:27508206

  1. Hedgehog signaling regulates liver sinusoidal endothelial cell capillarisation

    PubMed Central

    Xie, Guanhua; Choi, Steve S.; Syn, Wing-Kin; Michelotti, Gregory A.; Swiderska-Syn, Marzena; Karaca, Gamze; Chan, Isaac S.; Chen, Yuping; Diehl, Anna Mae

    2013-01-01

    Objective Vascular remodeling during liver damage involves loss of healthy liver sinusoidal endothelial cell (LSEC) phenotype via capillarisation. Hedgehog (Hh) signaling regulates vascular development and increases during liver injury. Therefore, we examined its role in capillarisation. Design Primary LSEC were cultured for 5 days to induce capillarisation. Pharmacologic, antibody-mediated, and genetic approaches were used to manipulate Hh signaling. Effects on mRNA and protein expression of Hh-regulated genes and capillarisation markers were evaluated by qRT-PCR and immunoblot. Changes in LSEC function were assessed by migration and tube forming assay, and gain/loss of fenestrae was examined by electron microscopy. Mice with acute or chronic liver injury were treated with Hh inhibitors; effects on capillarisation were assessed by immunohistochemistry. Results Freshly isolated LSEC expressed Hh ligands, Hh receptors, and Hh ligand antagonist Hhip. Capillarisation was accompanied by repression of Hhip and increased expression of Hh-regulated genes. Treatment with Hh agonist further induced expression of Hh ligands and Hh-regulated genes, and up-regulated capillarisation-associated genes; whereas Hh signaling antagonist or Hh ligand neutralizing antibody each repressed expression of Hh target genes and capillarisation markers. LSEC isolated from SmoloxP/loxP transgenic mice that had been infected with adenovirus expressing Cre-recombinase to delete Smoothened showed over 75% knockdown of Smoothened. During culture, Smoothened-deficient LSEC had inhibited Hh signaling, less induction of capillarisation-associated genes, and retention of fenestrae. In mice with injured livers, inhibiting Hh signaling prevented capillarisation. Conclusions LSEC produce and respond to Hh ligands, and use Hh signaling to regulate complex phenotypic changes that occur during capillarisation. PMID:22362915

  2. ERK5 MAP Kinase Regulates Neurogenin1 during Cortical Neurogenesis

    PubMed Central

    Cundiff, Paige; Liu, Lidong; Wang, Yupeng; Zou, Junhui; Pan, Yung-Wei; Abel, Glen; Duan, Xin; Ming, Guo-li; Englund, Chris; Hevner, Robert; Xia, Zhengui

    2009-01-01

    The commitment of multi-potent cortical progenitors to a neuronal fate depends on the transient induction of the basic-helix-loop-helix (bHLH) family of transcription factors including Neurogenin 1 (Neurog1). Previous studies have focused on mechanisms that control the expression of these proteins while little is known about whether their pro-neural activities can be regulated by kinase signaling pathways. Using primary cultures and ex vivo slice cultures, here we report that both the transcriptional and pro-neural activities of Neurog1 are regulated by extracellular signal-regulated kinase (ERK) 5 signaling in cortical progenitors. Activation of ERK5 potentiated, while blocking ERK5 inhibited Neurog1-induced neurogenesis. Furthermore, endogenous ERK5 activity was required for Neurog1-initiated transcription. Interestingly, ERK5 activation was sufficient to induce Neurog1 phosphorylation and ERK5 directly phosphorylated Neurog1 in vitro. We identified S179/S208 as putative ERK5 phosphorylation sites in Neurog1. Mutations of S179/S208 to alanines inhibited the transcriptional and pro-neural activities of Neurog1. Our data identify ERK5 phosphorylation of Neurog1 as a novel mechanism regulating neuronal fate commitment of cortical progenitors. PMID:19365559

  3. Endothelial cell expression of haemoglobin α regulates nitric oxide signalling.

    PubMed

    Straub, Adam C; Lohman, Alexander W; Billaud, Marie; Johnstone, Scott R; Dwyer, Scott T; Lee, Monica Y; Bortz, Pamela Schoppee; Best, Angela K; Columbus, Linda; Gaston, Benjamin; Isakson, Brant E

    2012-11-15

    Models of unregulated nitric oxide (NO) diffusion do not consistently account for the biochemistry of NO synthase (NOS)-dependent signalling in many cell systems. For example, endothelial NOS controls blood pressure, blood flow and oxygen delivery through its effect on vascular smooth muscle tone, but the regulation of these processes is not adequately explained by simple NO diffusion from endothelium to smooth muscle. Here we report a new model for the regulation of NO signalling by demonstrating that haemoglobin (Hb) α (encoded by the HBA1 and HBA2 genes in humans) is expressed in human and mouse arterial endothelial cells and enriched at the myoendothelial junction, where it regulates the effects of NO on vascular reactivity. Notably, this function is unique to Hb α and is abrogated by its genetic depletion. Mechanistically, endothelial Hb α haem iron in the Fe(3+) state permits NO signalling, and this signalling is shut off when Hb α is reduced to the Fe(2+) state by endothelial cytochrome b5 reductase 3 (CYB5R3, also known as diaphorase 1). Genetic and pharmacological inhibition of CYB5R3 increases NO bioactivity in small arteries. These data reveal a new mechanism by which the regulation of the intracellular Hb α oxidation state controls NOS signalling in non-erythroid cells. This model may be relevant to haem-containing globins in a broad range of NOS-containing somatic cells. PMID:23123858

  4. PTP-Pez: a novel regulator of TGFbeta signaling.

    PubMed

    Wyatt, Leila; Khew-Goodall, Yeesim

    2008-08-01

    The TGFbetas are a family of pleiotropic cytokines that mediate diverse effects including the regulation of cell cycle progression, apoptosis, tissue remodelling and epithelial-mesenchymal transition (EMT). These diverse effects allow the TGFbetas to play multiple and even opposing roles in different contexts during embryonal development, tissue homeostasis and cancer progression. We recently reported that the protein tyrosine phosphatase Pez is a novel inducer of TGFbeta signaling, regulating EMT and organogenesis in developing zebrafish embryos, and leading to TGFbeta-mediated EMT when overexpressed in vitro in epithelial MDCK cells. A number of mutations in Pez have been shown to be associated with breast and colorectal cancers, although the effect of these mutations on Pez function and their contribution to cancer progression remains unclear. Our finding that Pez regulates TGFbeta signaling is therefore of interest not only in the context of identifying a novel upstream regulator of TGFbeta signaling, but also in implicating the dysregulation of TGFbeta signaling as a possible link between Pez mutation and cancer progression. Here we discuss the implications of our research, in the context of dysregulation of TGFbeta signaling in cancer and other human pathologies. PMID:18677119

  5. Regulation, Signaling, and Physiological Functions of G-Proteins.

    PubMed

    Syrovatkina, Viktoriya; Alegre, Kamela O; Dey, Raja; Huang, Xin-Yun

    2016-09-25

    Heterotrimeric guanine-nucleotide-binding regulatory proteins (G-proteins) mainly relay the information from G-protein-coupled receptors (GPCRs) on the plasma membrane to the inside of cells to regulate various biochemical functions. Depending on the targeted cell types, tissues, and organs, these signals modulate diverse physiological functions. The basic schemes of heterotrimeric G-proteins have been outlined. In this review, we briefly summarize what is known about the regulation, signaling, and physiological functions of G-proteins. We then focus on a few less explored areas such as the regulation of G-proteins by non-GPCRs and the physiological functions of G-proteins that cannot be easily explained by the known G-protein signaling pathways. There are new signaling pathways and physiological functions for G-proteins to be discovered and further interrogated. With the advancements in structural and computational biological techniques, we are closer to having a better understanding of how G-proteins are regulated and of the specificity of G-protein interactions with their regulators. PMID:27515397

  6. Regulation, Signaling, and Physiological Functions of G-Proteins.

    PubMed

    Syrovatkina, Viktoriya; Alegre, Kamela O; Dey, Raja; Huang, Xin-Yun

    2016-09-25

    Heterotrimeric guanine-nucleotide-binding regulatory proteins (G-proteins) mainly relay the information from G-protein-coupled receptors (GPCRs) on the plasma membrane to the inside of cells to regulate various biochemical functions. Depending on the targeted cell types, tissues, and organs, these signals modulate diverse physiological functions. The basic schemes of heterotrimeric G-proteins have been outlined. In this review, we briefly summarize what is known about the regulation, signaling, and physiological functions of G-proteins. We then focus on a few less explored areas such as the regulation of G-proteins by non-GPCRs and the physiological functions of G-proteins that cannot be easily explained by the known G-protein signaling pathways. There are new signaling pathways and physiological functions for G-proteins to be discovered and further interrogated. With the advancements in structural and computational biological techniques, we are closer to having a better understanding of how G-proteins are regulated and of the specificity of G-protein interactions with their regulators.

  7. PECAM-1 ligation negatively regulates TLR4 signaling in macrophages.

    PubMed

    Rui, Yuxiang; Liu, Xingguang; Li, Nan; Jiang, Yingming; Chen, Guoyou; Cao, Xuetao; Wang, Jianli

    2007-12-01

    Uncontrolled TLR4 signaling may induce excessive production of proinflammatory cytokines and lead to harmful inflammation; therefore, negative regulation of TLR4 signaling attracts much attention now. PECAM-1, a member of Ig-ITIM family, can mediate inhibitory signals in T cells and B cells. However, the role and the mechanisms of PECAM-1 in the regulation of TLR4-mediated LPS response in macrophages remain unclear. In this study, we demonstrate that PECAM-1 ligation with CD38-Fc fusion protein negatively regulates LPS-induced proinflammatory cytokine TNF-alpha, IL-6, and IFN-beta production by inhibiting JNK, NF-kappaB, and IFN regulatory factor 3 activation in macrophages. In addition, PECAM-1 ligation-recruited Src homology region 2 domain-containing phosphatase 1 (SHP-1) and Src homology region 2 domain-containing phosphatase 2 (SHP-2) may be involved in the inhibitory effect of PECAM-1 on TLR4 signaling. Consistently, silencing of PECAM-1 enhances the macrophage response to LPS stimulation. Taken together with the data that PECAM-1 is constitutively expressed in macrophages and its expression is up-regulated by LPS stimulation, PECAM-1 might function as a feedback negative regulator of LPS inflammatory response in macrophages. This study may provide a potential target for intervention of inflammatory diseases. PMID:18025177

  8. Large-signal transient response of a switching regulator

    NASA Astrophysics Data System (ADS)

    Harada, K.; Nabeshima, T.

    Analytical and experimental considerations on the large-signal transient-responses of the buck-type switching regulator are described. The behaviour under the large-signal operation is different from the case of small signal because of the saturation characteristics of the PWM feedback controller. The effect of this nonlinearity is analyzed by dividing its operation into three modes. As a result, the maximum peak values of the inrush current and output voltage are obtained analytically both for the start-up and for the step change of the load current.

  9. THEMIS: a critical TCR signal regulator for ligand discrimination.

    PubMed

    Gascoigne, Nicholas R J; Acuto, Oreste

    2015-04-01

    Genetic approaches identified THEMIS as a critical element driving positive selection of CD4(+)CD8(+) thymocytes towards maturation. THEMIS is expressed only in the T-cell lineage, and is recruited to the proximity of signaling T-cell antigen receptors (TCR) by association with the membrane scaffold LAT. However, its molecular role remained an enigma until recently. Conventionally positively-selected T-cells are lacking in THEMIS-deficient mice, leading to the initial hypothesis that THEMIS positively regulates TCR signaling. Recent data show that THEMIS deficiency increases rather than decreases TCR signaling, leading to augmented apoptosis. The finding that THEMIS is constitutively bound to the tyrosine phosphatases SHP1 or SHP2, provides a mechanism for THEMIS action. When recruited onto LAT, THEMIS-SHP promotes immediate dephosphorylation of TCR-proximal signaling components. This negative feedback is central in setting sharp signaling thresholds and helps explain the exquisite ligand discrimination by the TCR, particularly during thymocyte selection.

  10. Potential Mechanisms Underlying Intercortical Signal Regulation via Cholinergic Neuromodulators

    PubMed Central

    Whittington, Miles A.; Kopell, Nancy J.

    2015-01-01

    The dynamical behavior of the cortex is extremely complex, with different areas and even different layers of a cortical column displaying different temporal patterns. A major open question is how the signals from different layers and different brain regions are coordinated in a flexible manner to support function. Here, we considered interactions between primary auditory cortex and adjacent association cortex. Using a biophysically based model, we show how top-down signals in the beta and gamma regimes can interact with a bottom-up gamma rhythm to provide regulation of signals between the cortical areas and among layers. The flow of signals depends on cholinergic modulation: with only glutamatergic drive, we show that top-down gamma rhythms may block sensory signals. In the presence of cholinergic drive, top-down beta rhythms can lift this blockade and allow signals to flow reciprocally between primary sensory and parietal cortex. SIGNIFICANCE STATEMENT Flexible coordination of multiple cortical areas is critical for complex cognitive functions, but how this is accomplished is not understood. Using computational models, we studied the interactions between primary auditory cortex (A1) and association cortex (Par2). Our model is capable of replicating interaction patterns observed in vitro and the simulations predict that the coordination between top-down gamma and beta rhythms is central to the gating process regulating bottom-up sensory signaling projected from A1 to Par2 and that cholinergic modulation allows this coordination to occur. PMID:26558772

  11. Regulation of dopamine D2 receptor-mediated extracellular signal-regulated kinase signaling and spine formation by GABAA receptors in hippocampal neurons.

    PubMed

    Yoon, Dong-Hoon; Yoon, Sehyoun; Kim, Donghoon; Kim, Hyun; Baik, Ja-Hyun

    2015-01-23

    Dopamine (DA) signaling via DA receptors is known to control hippocampal activity that contributes to learning, memory, and synaptic plasticity. In primary hippocampal neuronal culture, we observed that dopamine D2 receptors (D2R) co-localized with certain subtypes of GABAA receptors, namely α1, β3, and γ2 subunits, as revealed by double immunofluorocytochemical analysis. Treatment with the D2R agonist, quinpirole, was shown to elicit an increase in phosphorylation of extracellular signal-regulated kinase (ERK) in hippocampal neurons. This phosphorylation was inhibited by pretreatment with the GABAA receptor agonist, muscimol. Furthermore, treatment of hippocampal neurons with quinpirole increased the dendritic spine density and this regulation was totally blocked by pretreatment with a MAP kinase kinase (MEK) inhibitor (PD98059), D2R antagonist (haloperidol), or by the GABAA receptor agonist, muscimol. These results suggest that D2R-mediated ERK phosphorylation can control spine formation and that the GABAA receptor negatively regulates the D2R-induced spine formation through ERK signaling in hippocampal neurons, thus indicating a potential role of D2R in the control of hippocampal neuronal excitability. PMID:25483619

  12. Insulin/IGF signaling and its regulation in Drosophila.

    PubMed

    Nässel, Dick R; Liu, Yiting; Luo, Jiangnan

    2015-09-15

    Taking advantage of Drosophila as a genetically tractable experimental animal much progress has been made in our understanding of how the insulin/IGF signaling (IIS) pathway regulates development, growth, metabolism, stress responses and lifespan. The role of IIS in regulation of neuronal activity and behavior has also become apparent from experiments in Drosophila. This review briefly summarizes these functional roles of IIS, and also how the insulin producing cells (IPCs) are regulated in the fly. Furthermore, we discuss functional aspects of the spatio-temporal production of eight different insulin-like peptides (DILP1-8) that are thought to act on one known receptor (dInR) in Drosophila.

  13. Organelle size: a cilium length signal regulates IFT cargo loading.

    PubMed

    Pan, Junmin; Snell, William J

    2014-01-20

    Cilia grow by assembling structural precursors delivered to their tips by intraflagellar transport. New work on ciliary length control indicates that, during ciliary growth, cilia send a length signal to the cytoplasm that regulates cargo loading onto the constitutively trafficking intraflagellar transport machinery.

  14. Regulation of Mitoflash Biogenesis and Signaling by Mitochondrial Dynamics

    PubMed Central

    Li, Wenwen; Sun, Tao; Liu, Beibei; Wu, Di; Qi, Wenfeng; Wang, Xianhua; Ma, Qi; Cheng, Heping

    2016-01-01

    Mitochondria are highly dynamic organelles undergoing constant network reorganization and exhibiting stochastic signaling events in the form of mitochondrial flashes (mitoflashes). Here we investigate whether and how mitochondrial network dynamics regulate mitoflash biogenesis and signaling. We found that mitoflash frequency was largely invariant when network fragmentized or redistributed in the absence of mitofusin (Mfn) 1, Mfn2, or Kif5b. However, Opa1 deficiency decreased spontaneous mitoflash frequency due to superimposing changes in respiratory function, whereas mitoflash response to non-metabolic stimulation was unchanged despite network fragmentation. In Drp1- or Mff-deficient cells whose mitochondria hyperfused into a single whole-cell reticulum, the frequency of mitoflashes of regular amplitude and duration was again unaltered, although brief and low-amplitude “miniflashes” emerged because of improved detection ability. As the network reorganized, however, the signal mass of mitoflash signaling was dynamically regulated in accordance with the degree of network connectivity. These findings demonstrate a novel functional role of mitochondrial network dynamics and uncover a magnitude- rather than frequency-modulatory mechanism in the regulation of mitoflash signaling. In addition, our data support a stochastic trigger model for the ignition of mitoflashes. PMID:27623243

  15. SYK Regulates mTOR Signaling in AML

    PubMed Central

    Carnevale, Julia; Ross, Linda; Puissant, Alexandre; Banerji, Versha; Stone, Richard M.; DeAngelo, Daniel J.; Ross, Kenneth N.; Stegmaier, Kimberly

    2014-01-01

    Spleen Tyrosine Kinase (SYK) was recently identified as a new target in acute myeloid leukemia (AML); however, its mechanistic role in this disease is poorly understood. Based on the known interaction between SYK and mTOR signaling in lymphoma, we hypothesized that SYK may regulate mTOR signaling in AML. Both small-molecule inhibition of SYK and SYK-directed shRNA suppressed mTOR and its downstream signaling effectors, as well as its upstream activator, AKT. Moreover, the inhibition of multiple nodes of the PI3K signaling pathway enhanced the effects of SYK suppression on AML cell viability and differentiation. Evaluation of the collateral MAPK pathway revealed a heterogeneous response to SYK inhibition in AML with down-regulation of MEK and ERK phosphorylation in some AML cell lines but a paradoxical increase in MEK/ERK phosphorylation in RAS-mutated AML. These studies reveal SYK as a regulator of mTOR and MAPK signaling in AML and demonstrate that inhibition of PI3K pathway activity enhances the effects of SYK inhibition on AML cell viability and differentiation. PMID:23535559

  16. Regulation of Mitoflash Biogenesis and Signaling by Mitochondrial Dynamics.

    PubMed

    Li, Wenwen; Sun, Tao; Liu, Beibei; Wu, Di; Qi, Wenfeng; Wang, Xianhua; Ma, Qi; Cheng, Heping

    2016-01-01

    Mitochondria are highly dynamic organelles undergoing constant network reorganization and exhibiting stochastic signaling events in the form of mitochondrial flashes (mitoflashes). Here we investigate whether and how mitochondrial network dynamics regulate mitoflash biogenesis and signaling. We found that mitoflash frequency was largely invariant when network fragmentized or redistributed in the absence of mitofusin (Mfn) 1, Mfn2, or Kif5b. However, Opa1 deficiency decreased spontaneous mitoflash frequency due to superimposing changes in respiratory function, whereas mitoflash response to non-metabolic stimulation was unchanged despite network fragmentation. In Drp1- or Mff-deficient cells whose mitochondria hyperfused into a single whole-cell reticulum, the frequency of mitoflashes of regular amplitude and duration was again unaltered, although brief and low-amplitude "miniflashes" emerged because of improved detection ability. As the network reorganized, however, the signal mass of mitoflash signaling was dynamically regulated in accordance with the degree of network connectivity. These findings demonstrate a novel functional role of mitochondrial network dynamics and uncover a magnitude- rather than frequency-modulatory mechanism in the regulation of mitoflash signaling. In addition, our data support a stochastic trigger model for the ignition of mitoflashes. PMID:27623243

  17. Lipid rafts as major platforms for signaling regulation in cancer.

    PubMed

    Mollinedo, Faustino; Gajate, Consuelo

    2015-01-01

    Cell signaling does not apparently occur randomly over the cell surface, but it seems to be integrated very often into cholesterol-rich membrane domains, termed lipid rafts. Membrane lipid rafts are highly ordered membrane domains that are enriched in cholesterol, sphingolipids and gangliosides, and behave as major modulators of membrane geometry, lateral movement of molecules, traffic and signal transduction. Because the lipid and protein composition of membrane rafts differs from that of the surrounding membrane, they provide an additional level of compartmentalization, serving as sorting platforms and hubs for signal transduction proteins. A wide number of signal transduction processes related to cell adhesion, migration, as well as to cell survival and proliferation, which play major roles in cancer development and progression, are dependent on lipid rafts. Despite lipid rafts harbor mainly critical survival signaling pathways, including insulin-like growth factor I (IGF-I)/phosphatidylinositol 3-kinase (PI3K)/Akt signaling, recent evidence suggests that these membrane domains can also house death receptor-mediated apoptotic signaling. Recruitment of this death receptor signaling pathway in membrane rafts can be pharmacologically modulated, thus opening up the possibility to regulate cell demise with a therapeutic use. The synthetic ether phospholipid edelfosine shows a high affinity for cholesterol and accumulates in lipid rafts in a number of malignant hematological cells, leading to an efficient in vitro and in vivo antitumor activity by inducing translocation of death receptors and downstream signaling molecules to these membrane domains. Additional antitumor drugs have also been shown to act, at least in part, by recruiting death receptors in lipid rafts. The partition of death receptors together with downstream apoptotic signaling molecules in membrane rafts has led us to postulate the concept of a special liquid-ordered membrane platform coined as

  18. Signaling networks regulating leukocyte podosome dynamics and function

    PubMed Central

    Dovas, Athanassios; Cox, Dianne

    2011-01-01

    Podosomes are ventral adhesion structures prominent in cells of the myeloid lineage. A common aspect of these cells is that they are highly motile and are required to traverse multiple tissue barriers in order to perform their functions. Recently podosomes have gathered attention from researchers as important cellular structures that can influence cell adhesion, motility and matrix remodeling. Adhesive and soluble ligands act via transmembrane receptors and propagate signals to the leukocyte cytoskeleton via small G proteins of the Rho family, tyrosine kinases and scaffold proteins and are able to induce podosome formation and rearrangements. Manipulation of the signals that regulate podosome formation and dynamics can therefore be a strategy to interfere with leukocyte functions in a multitude of pathological settings, such as infections, atherosclerosis and arthritis. Here, we review the major signaling molecules that act in the formation and regulation of podosomes. PMID:21342664

  19. Copper as a key regulator of cell signalling pathways.

    PubMed

    Grubman, Alexandra; White, Anthony R

    2014-05-22

    Copper is an essential element in many biological processes. The critical functions associated with copper have resulted from evolutionary harnessing of its potent redox activity. This same property also places copper in a unique role as a key modulator of cell signal transduction pathways. These pathways are the complex sequence of molecular interactions that drive all cellular mechanisms and are often associated with the interplay of key enzymes including kinases and phosphatases but also including intracellular changes in pools of smaller molecules. A growing body of evidence is beginning to delineate the how, when and where of copper-mediated control over cell signal transduction. This has been driven by research demonstrating critical changes to copper homeostasis in many disorders including cancer and neurodegeneration and therapeutic potential through control of disease-associated cell signalling changes by modulation of copper-protein interactions. This timely review brings together for the first time the diverse actions of copper as a key regulator of cell signalling pathways and discusses the potential strategies for controlling disease-associated signalling processes using copper modulators. It is hoped that this review will provide a valuable insight into copper as a key signal regulator and stimulate further research to promote our understanding of copper in disease and therapy.

  20. YAP regulates neuronal differentiation through Sonic hedgehog signaling pathway

    SciTech Connect

    Lin, Yi-Ting; Ding, Jing-Ya; Li, Ming-Yang; Yeh, Tien-Shun; Wang, Tsu-Wei; Yu, Jenn-Yah

    2012-09-10

    Tight regulation of cell numbers by controlling cell proliferation and apoptosis is important during development. Recently, the Hippo pathway has been shown to regulate tissue growth and organ size in Drosophila. In mammalian cells, it also affects cell proliferation and differentiation in various tissues, including the nervous system. Interplay of several signaling cascades, such as Notch, Wnt, and Sonic Hedgehog (Shh) pathways, control cell proliferation during neuronal differentiation. However, it remains unclear whether the Hippo pathway coordinates with other signaling cascades in regulating neuronal differentiation. Here, we used P19 cells, a mouse embryonic carcinoma cell line, as a model to study roles of YAP, a core component of the Hippo pathway, in neuronal differentiation. P19 cells can be induced to differentiate into neurons by expressing a neural bHLH transcription factor gene Ascl1. Our results showed that YAP promoted cell proliferation and inhibited neuronal differentiation. Expression of Yap activated Shh but not Wnt or Notch signaling activity during neuronal differentiation. Furthermore, expression of Yap increased the expression of Patched homolog 1 (Ptch1), a downstream target of the Shh signaling. Knockdown of Gli2, a transcription factor of the Shh pathway, promoted neuronal differentiation even when Yap was over-expressed. We further demonstrated that over-expression of Yap inhibited neuronal differentiation in primary mouse cortical progenitors and Gli2 knockdown rescued the differentiation defect in Yap over-expressing cells. In conclusion, our study reveals that Shh signaling acts downstream of YAP in regulating neuronal differentiation. -- Highlights: Black-Right-Pointing-Pointer YAP promotes cell proliferation and inhibits neuronal differentiation in P19 cells. Black-Right-Pointing-Pointer YAP promotes Sonic hedgehog signaling activity during neuronal differentiation. Black-Right-Pointing-Pointer Knockdown of Gli2 rescues the Yap

  1. Olfactory plasticity is regulated by pheromonal signaling in Caenorhabditis elegans

    PubMed Central

    Yamada, Koji; Hirotsu, Takaaki; Matsuki, Masahiro; Butcher, Rebecca A; Tomioka, Masahiro; Ishihara, Takeshi; Clardy, Jon; Kunitomo, Hirofumi; Iino, Yuichi

    2011-01-01

    Population density-dependent dispersal is a well-characterized strategy of animal behavior in which dispersal rate increases when population density is higher. C. elegans shows positive chemotaxis to a set of odorants, but the chemotaxis switches from attraction to dispersal after prolonged exposure to the odorants. We show here that this plasticity of olfactory behavior is dependent on population density and this regulation is mediated by pheromonal signaling. We show that a peptide SNET-1 negatively regulates olfactory plasticity and its expression is down-regulated by the pheromone. NEP-2, a homologue of the extracellular peptidase neprilysin, antagonizes SNET-1 and this function is essential for olfactory plasticity. These results suggest that population density information is transmitted through the external pheromone and endogenous peptide signaling to modulate chemotactic behavior. PMID:20929849

  2. The role of the extracellular signal-regulated kinase signaling pathway in mood modulation.

    PubMed

    Einat, Haim; Yuan, Peixiong; Gould, Todd D; Li, Jianling; Du, JianHua; Zhang, Lei; Manji, Husseini K; Chen, Guang

    2003-08-13

    The neurobiological underpinnings of mood modulation, molecular pathophysiology of manic-depressive illness, and therapeutic mechanism of mood stabilizers are largely unknown. The extracellular signal-regulated kinase (ERK) pathway is activated by neurotrophins and other neuroactive chemicals to produce their effects on neuronal differentiation, survival, regeneration, and structural and functional plasticity. We found that lithium and valproate, commonly used mood stabilizers for the treatment of manic-depressive illness, stimulated the ERK pathway in the rat hippocampus and frontal cortex. Both drugs increased the levels of activated phospho-ERK44/42, activated phospho-ribosomal protein S6 kinase-1 (RSK1) (a substrate of ERK), phospho-CREB (cAMP response element-binding protein) and phospho-B cell lymphoma protein-2 antagonist of cell death (substrates of RSK), and BDNF. Inhibiting the ERK pathway with the blood-brain barrier-penetrating mitogen-activated protein kinase (MAP kinase)/ERK kinase (MEK) kinase inhibitor SL327, but not with the nonblood-brain barrier-penetrating MEK inhibitor U0126, decreased immobility time and increased swimming time of rats in the forced-swim test. SL327, but not U0126, also increased locomotion time and distance traveled in a large open field. The behavioral changes in the open field were prevented with chronic lithium pretreatment. SL327-induced behavioral changes are qualitatively similar to the changes induced by amphetamine, a compound that induces relapse in remitted manic patients and mood elevation in normal subjects. These data suggest that the ERK pathway may mediate the antimanic effects of mood stabilizers.

  3. Arabidopsis MAP kinase 4 regulates gene expression through transcription factor release in the nucleus.

    PubMed

    Qiu, Jin-Long; Fiil, Berthe Katrine; Petersen, Klaus; Nielsen, Henrik Bjørn; Botanga, Christopher J; Thorgrimsen, Stephan; Palma, Kristoffer; Suarez-Rodriguez, Maria Cristina; Sandbech-Clausen, Signe; Lichota, Jacek; Brodersen, Peter; Grasser, Klaus D; Mattsson, Ole; Glazebrook, Jane; Mundy, John; Petersen, Morten

    2008-08-20

    Plant and animal perception of microbes through pathogen surveillance proteins leads to MAP kinase signalling and the expression of defence genes. However, little is known about how plant MAP kinases regulate specific gene expression. We report that, in the absence of pathogens, Arabidopsis MAP kinase 4 (MPK4) exists in nuclear complexes with the WRKY33 transcription factor. This complex depends on the MPK4 substrate MKS1. Challenge with Pseudomonas syringae or flagellin leads to the activation of MPK4 and phosphorylation of MKS1. Subsequently, complexes with MKS1 and WRKY33 are released from MPK4, and WRKY33 targets the promoter of PHYTOALEXIN DEFICIENT3 (PAD3) encoding an enzyme required for the synthesis of antimicrobial camalexin. Hence, wrky33 mutants are impaired in the accumulation of PAD3 mRNA and camalexin production upon infection. That WRKY33 is an effector of MPK4 is further supported by the suppression of PAD3 expression in mpk4-wrky33 double mutant backgrounds. Our data establish direct links between MPK4 and innate immunity and provide an example of how a plant MAP kinase can regulate gene expression by releasing transcription factors in the nucleus upon activation.

  4. TGF-β Signaling in Stem Cell Regulation.

    PubMed

    Li, Wenlin; Wei, Wanguo; Ding, Sheng

    2016-01-01

    The transforming growth factor-β (TGF-β) family of cytokines, including TGF-β, bone morphogenic proteins (BMPs), and activin/nodal, is a group of crucial morphogens in embryonic development, and plays key roles in modulating stem/progenitor cell fate. TGF-β signaling is essential in maintaining the pluripotency of human pluripotent stem cells (hPSCs), including both human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), and its modulation can direct lineage-specific differentiation. Recent studies also demonstrate TGF-β signaling negatively regulates reprogramming and inhibition of TGF-β signaling can enhance reprogramming through facilitating mesenchymal-to-epithelial transition (MET). This chapter introduces methods of modulating somatic cell reprogramming to iPSCs and neural induction from hPSCs through modulating TGF-β signaling by chemical approaches.

  5. Mechanosensitive β-catenin signaling regulates lymphatic vascular development.

    PubMed

    Cha, Boksik; Srinivasan, R Sathish

    2016-08-01

    The Wnt/β-catenin signaling is an evolutionarily conserved pathway that plays a pivotal role in embryonic development and adult homeostasis. However, we have limited information about the involvement of Wnt/β-catenin signaling in the lymphatic vascular system that regulates fluid homeostasis by absorbing interstitial fluid and returning it to blood circulation. In this recent publication we report that canonical Wnt/β-catenin signaling is highly active and critical for the formation of lymphovenus valves (LVVs) and lymphatic valves (LVs). β-catenin directly associates with the regulatory elements of the lymphedema-associated transcription factor, FOXC2 and activates its expression in an oscillatory shear stress (OSS)-dependent manner. The phenotype of β-catenin null embryos was rescued by FOXC2 overexpression. These results suggest that Wnt/β-catenin signaling is a mechanotransducer that links fluid force with lymphatic vascular development. [BMB Reports 2016; 49(8): 403-404]. PMID:27418286

  6. Dendrosomatic Sonic Hedgehog Signaling in Hippocampal Neurons Regulates Axon Elongation

    PubMed Central

    Petralia, Ronald S.; Ott, Carolyn; Wang, Ya-Xian; Lippincott-Schwartz, Jennifer; Mattson, Mark P.

    2015-01-01

    The presence of Sonic Hedgehog (Shh) and its signaling components in the neurons of the hippocampus raises a question about what role the Shh signaling pathway may play in these neurons. We show here that activation of the Shh signaling pathway stimulates axon elongation in rat hippocampal neurons. This Shh-induced effect depends on the pathway transducer Smoothened (Smo) and the transcription factor Gli1. The axon itself does not respond directly to Shh; instead, the Shh signal transduction originates from the somatodendritic region of the neurons and occurs in neurons with and without detectable primary cilia. Upon Shh stimulation, Smo localization to dendrites increases significantly. Shh pathway activation results in increased levels of profilin1 (Pfn1), an actin-binding protein. Mutations in Pfn1's actin-binding sites or reduction of Pfn1 eliminate the Shh-induced axon elongation. These findings indicate that Shh can regulate axon growth, which may be critical for development of hippocampal neurons. SIGNIFICANCE STATEMENT Although numerous signaling mechanisms have been identified that act directly on axons to regulate their outgrowth, it is not known whether signals transduced in dendrites may also affect axon outgrowth. We describe here a transcellular signaling pathway in embryonic hippocampal neurons in which activation of Sonic Hedgehog (Shh) receptors in dendrites stimulates axon growth. The pathway involves the dendritic-membrane-associated Shh signal transducer Smoothened (Smo) and the transcription factor Gli, which induces the expression of the gene encoding the actin-binding protein profilin 1. Our findings suggest scenarios in which stimulation of Shh in dendrites results in accelerated outgrowth of the axon, which therefore reaches its presumptive postsynaptic target cell more quickly. By this mechanism, Shh may play critical roles in the development of hippocampal neuronal circuits. PMID:26658865

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

    SciTech Connect

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

    2006-03-10

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

  8. The transcription factor Zeb2 regulates signaling in mast cells.

    PubMed

    Barbu, Emilia Alina; Zhang, Juan; Berenstein, Elsa H; Groves, Jacqueline R; Parks, Lauren M; Siraganian, Reuben P

    2012-06-15

    Mast cell activation results in the release of stored and newly synthesized inflammatory mediators. We found that Zeb2 (also named Sip1, Zfhx1b), a zinc finger transcription factor, regulates both early and late mast cell responses. Transfection with small interfering RNA (siRNA) reduced Zeb2 expression and resulted in decreased FcεRI-mediated degranulation, with a parallel reduction in receptor-induced activation of NFAT and NF-κB transcription factors, but an enhanced response to the LPS-mediated activation of NF-κB. There was variable and less of a decrease in the Ag-mediated release of the cytokines TNF-α, IL-13, and CCL-4. This suggests that low Zeb2 expression differentially regulates signaling pathways in mast cells. Multiple phosphorylation events were impaired that affected molecules both at early and late events in the signaling pathway. The Zeb2 siRNA-treated mast cells had altered cell cycle progression, as well as decreased expression of several molecules including cell surface FcεRI and its β subunit, Gab2, phospholipase-Cγ1, and phospholipase-Cγ2, all of which are required for receptor-induced signal transduction. The results indicate that the transcription factor Zeb2 controls the expression of molecules thereby regulating signaling in mast cells.

  9. Notch signaling regulates gastric antral LGR5 stem cell function

    PubMed Central

    Demitrack, Elise S; Gifford, Gail B; Keeley, Theresa M; Carulli, Alexis J; VanDussen, Kelli L; Thomas, Dafydd; Giordano, Thomas J; Liu, Zhenyi; Kopan, Raphael; Samuelson, Linda C

    2015-01-01

    The major signaling pathways regulating gastric stem cells are unknown. Here we report that Notch signaling is essential for homeostasis of LGR5+ antral stem cells. Pathway inhibition reduced proliferation of gastric stem and progenitor cells, while activation increased proliferation. Notch dysregulation also altered differentiation, with inhibition inducing mucous and endocrine cell differentiation while activation reduced differentiation. Analysis of gastric organoids demonstrated that Notch signaling was intrinsic to the epithelium and regulated growth. Furthermore, in vivo Notch manipulation affected the efficiency of organoid initiation from glands and single Lgr5-GFP stem cells, suggesting regulation of stem cell function. Strikingly, constitutive Notch activation in LGR5+ stem cells induced tissue expansion via antral gland fission. Lineage tracing using a multi-colored reporter demonstrated that Notch-activated stem cells rapidly generate monoclonal glands, suggesting a competitive advantage over unmanipulated stem cells. Notch activation was associated with increased mTOR signaling, and mTORC1 inhibition normalized NICD-induced increases in proliferation and gland fission. Chronic Notch activation induced undifferentiated, hyper-proliferative polyps, suggesting that aberrant activation of Notch in gastric stem cells may contribute to gastric tumorigenesis. PMID:26271103

  10. Regulation of Cardiac Hypertrophic Signaling by Prolyl Isomerase Pin1

    PubMed Central

    Toko, Haruhiro; Konstandin, Mathias H.; Doroudgar, Shirin; Ormachea, Lucia; Joyo, Eri; Joyo, Anya Y.; Din, Shabana; Gude, Natalie A.; Collins, Brett; Völkers, Mirko; Thuerauf, Donna J.; Glembotski, Christopher C.; Chen, Chun-Hau; Lu, Kun Ping; Müller, Oliver J.; Uchida, Takafumi; Sussman, Mark A.

    2013-01-01

    Rationale Cardiac hypertrophy results from the complex interplay of differentially regulated cascades based upon the phosphorylation status of involved signaling molecules. While numerous critical regulatory kinases and phosphatases have been identified in the myocardium, the intracellular mechanism for temporal regulation of signaling duration and intensity remains obscure. In the non-myocyte context, control of folding, activity, and stability of proteins is mediated by the prolyl isomerase Pin1, but the role of Pin1 in the heart is unknown. Objective To establish the role of Pin1 in the heart. Methods and Results Here we show that either genetic deletion or cardiac over-expression of Pin1 blunts hypertrophic responses induced by transaortic constriction and consequent cardiac failure in vivo. Mechanistically, we find that Pin1 directly binds to Akt, MEK and Raf-1 in cultured cardiomyocytes following hypertrophic stimulation. Furthermore, loss of Pin1 leads to diminished hypertrophic signaling of Akt and MEK, while over-expression of Pin1 increases Raf-1 phosphorylation on the auto-inhibitory site Ser259 leading to reduced MEK activation. Conclusions Collectively, these data support a role for Pin1 as a central modulator of the intensity and duration of two major hypertrophic signaling pathways, thereby providing a novel target for regulation and control of cardiac hypertrophy. PMID:23487407

  11. TGF-β Signaling Regulates Cementum Formation through Osterix Expression

    PubMed Central

    Choi, Hwajung; Ahn, Yu-Hyun; Kim, Tak-Heun; Bae, Cheol-Hyeon; Lee, Jeong-Chae; You, Hyung-Keun; Cho, Eui-Sic

    2016-01-01

    TGF-β/BMPs have widely recognized roles in mammalian development, including in bone and tooth formation. To define the functional relevance of the autonomous requirement for TGF-β signaling in mouse tooth development, we analyzed osteocalcin-Cre mediated Tgfbr2 (OCCreTgfbr2fl/fl) conditional knockout mice, which lacks functional TGF-β receptor II (TβRII) in differentiating cementoblasts and cementocytes. Strikingly, OCCreTgfbr2fl/fl mutant mice exhibited a sharp reduction in cellular cementum mass with reduced matrix secretion and mineral apposition rates. To explore the molecular mechanisms underlying the roles of TGF-β signaling through TβRII in cementogenesis, we established a mouse cementoblast model with decreased TβRII expression using OCCM-30 cells. Interestingly, the expression of osterix (Osx), one of the major regulators of cellular cementum formation, was largely decreased in OCCM-30 cells lacking TβRII. Consequently, in those cells, functional ALP activity and the expression of genes associated with cementogenesis were reduced and the cells were partially rescued by Osx transduction. We also found that TGF-β signaling directly regulates Osx expression through a Smad-dependent pathway. These findings strongly suggest that TGF-β signaling plays a major role as one of the upstream regulators of Osx in cementoblast differentiation and cementum formation. PMID:27180803

  12. SEPT4 is regulated by the Notch signaling pathway.

    PubMed

    Liu, Wenbin

    2012-04-01

    Notch receptor-mediated signaling is an evolutionarily conserved pathway that regulates diverse developmental processes and its dysregulation has been implicated in a variety of developmental disorders and cancers. Notch functions in these processes by activating expression of its target genes. Septin 4 (SEPT4) is a polymerizing GTP-binding protein that serves as scaffold for diverse molecules and is involved in cell proliferation and apoptosis. After activation of the Notch signal, the expression of SEPT4 is up-regulated and cell proliferation is inhibited. When the Notch signal is inhibited by the CSL (CBF1/Su(H)/Lag-1)-binding-domain-negative Mastermind-like protein 1, the expression of SEPT4 is down-regulated, proliferation and colony formation of cells are promoted, but cell adhesion ability is decreased. Nevertheless, the SEPT4 expression is not affected after knock-down of CSL. Meanwhile, if SEPT4 activity is inhibited through RNA interference, the protein level and activity of NOTCH1 remains unchanged, but cell proliferation is dysregulated. This indicates that SEPT4 is a Notch target gene. This relationship between Notch signaling pathway and SEPT4 offers a potential basis for further study of developmental control and carcinogenesis. PMID:21938432

  13. Stress regulates endocannabinoid-CB1 receptor signaling.

    PubMed

    Hillard, Cecilia J

    2014-10-01

    The CB1 cannabinoid receptor is a G protein coupled receptor that is widely expressed throughout the brain. The endogenous ligands for the CB1 receptor (endocannabinoids) are N-arachidonylethanolamine and 2-arachidonoylglycerol; together the endocannabinoids and CB1R subserve activity dependent, retrograde inhibition of neurotransmitter release in the brain. Deficiency of CB1 receptor signaling is associated with anhedonia, anxiety, and persistence of negative memories. CB1 receptor-endocannabinoid signaling is activated by stress and functions to buffer or dampen the behavioral and endocrine effects of acute stress. Its role in regulation of neuronal responses is more complex. Chronic variable stress exposure reduces endocannabinoid-CB1 receptor signaling and it is hypothesized that the resultant deficiency in endocannabinoid signaling contributes to the negative consequences of chronic stress. On the other hand, repeated exposure to the same stress can sensitize CB1 receptor signaling, resulting in dampening of the stress response. Data are reviewed that support the hypothesis that CB1 receptor signaling is stress responsive and that maintaining robust endocannabinoid/CB1 receptor signaling provides resilience against the development of stress-related pathologies.

  14. Phosphoinositides Regulate Ciliary Protein Trafficking to Modulate Hedgehog Signaling

    PubMed Central

    Roberson, Elle C.; Garcia, Galo; Abedin, Monika; Schurmans, Stéphane; Inoue, Takanari; Reiter, Jeremy F.

    2015-01-01

    SUMMARY Primary cilia interpret vertebrate Hedgehog (Hh) signals. Why cilia are essential for signaling is unclear. One possibility is that some forms of signaling require a distinct membrane lipid composition, found at cilia. We found that the ciliary membrane contains a particular phosphoinositide, PI(4)P, whereas a different phosphoinositide, PI(4,5)P2, is restricted to the membrane of the ciliary base. This distribution is created by Inpp5e, a ciliary phosphoinositide 5-phosphatase. Without Inpp5e, ciliary PI(4,5)P2 levels are elevated and Hh signaling is disrupted. Inpp5e limits the ciliary levels of inhibitors of Hh signaling, including Gpr161 and the PI(4,5)P2-binding protein Tulp3. Increasing ciliary PI(4,5)P2 levels or conferring the ability to bind PI(4)P on Tulp3 increases the ciliary localization of Tulp3. Lowering Tulp3 in cells lacking Inpp5e reduces ciliary Gpr161 levels and restores Hh signaling. Therefore, Inpp5e regulates ciliary membrane phosphoinositide composition, and Tulp3 reads out ciliary phosphoinositides to control ciliary protein localization, enabling Hh signaling. PMID:26305592

  15. Cytokinin signaling regulates pavement cell morphogenesis in Arabidopsis.

    PubMed

    Li, Hongjiang; Xu, Tongda; Lin, Deshu; Wen, Mingzhang; Xie, Mingtang; Duclercq, Jérôme; Bielach, Agnieszka; Kim, Jungmook; Reddy, G Venugopala; Zuo, Jianru; Benková, Eva; Friml, Jiří; Guo, Hongwei; Yang, Zhenbiao

    2013-02-01

    The puzzle piece-shaped Arabidopsis leaf pavement cells (PCs) with interdigitated lobes and indents is a good model system to investigate the mechanisms that coordinate cell polarity and shape formation within a tissue. Auxin has been shown to coordinate the interdigitation by activating ROP GTPase-dependent signaling pathways. To identify additional components or mechanisms, we screened for mutants with abnormal PC morphogenesis and found that cytokinin signaling regulates the PC interdigitation pattern. Reduction in cytokinin accumulation and defects in cytokinin signaling (such as in ARR7-over-expressing lines, the ahk3cre1 cytokinin receptor mutant, and the ahp12345 cytokinin signaling mutant) enhanced PC interdigitation, whereas over-production of cytokinin and over-activation of cytokinin signaling in an ARR20 over-expression line delayed or abolished PC interdigitation throughout the cotyledon. Genetic and biochemical analyses suggest that cytokinin signaling acts upstream of ROPs to suppress the formation of interdigitated pattern. Our results provide novel mechanistic understanding of the pathways controlling PC shape and uncover a new role for cytokinin signaling in cell morphogenesis.

  16. Irisin promotes osteoblast proliferation and differentiation via activating the MAP kinase signaling pathways.

    PubMed

    Qiao, Xiaoyong; Yong Qiao, Xiao; Nie, Ying; Ma, Yaxian; Xian Ma, Ya; Chen, Yan; Cheng, Ran; Yin, Weiyao; Yao Yinrg, Wei; Hu, Ying; Xu, Wenming; Ming Xu, Wen; Xu, Liangzhi; Zhi Xu, Liang

    2016-01-07

    Physical exercise is able to improve skeletal health. However, the mechanisms are poorly known. Irisin, a novel exercise-induced myokine, secreted by skeletal muscle in response to exercise, have been shown to mediate beneficial effects of exercise in many disorders. In the current study, we demonstrated that irisin promotes osteoblast proliferation, and increases the expression of osteoblastic transcription regulators, such as Runt-related transcription factor-2, osterix/sp7; and osteoblast differentiation markers, including alkaline phosphatase, collagen type 1 alpha-1, osteocalcin, and osteopontin in vitro. Irisin also increase ALP activity and calcium deposition in cultured osteoblast. These osteogenic effects were mediated by activating the p38 mitogen-activated protein kinase (p-p38 MAPK) and extracellular signal-regulated kinase (ERK). Inhibition of p38 MAPK by SB023580 or pERK by U0126 abolished the proliferation and up-regulatory effects of irisin on Runx2 expression and ALP activity. Together our observation suggest that irisin directly targets osteoblast, promoting osteoblast proliferation and differentiation via activating P38/ERK MAP kinase signaling cascades in vitro. Whether irisin can be utilized as the therapeutic agents for osteopenia and osteoporosis is worth to be further pursued.

  17. Irisin promotes osteoblast proliferation and differentiation via activating the MAP kinase signaling pathways

    PubMed Central

    Yong Qiao, Xiao; Nie, Ying; Xian Ma, Ya; Chen, Yan; Cheng, Ran; Yao Yinrg, Wei; Hu, Ying; Ming Xu, Wen; Zhi Xu, Liang

    2016-01-01

    Physical exercise is able to improve skeletal health. However, the mechanisms are poorly known. Irisin, a novel exercise-induced myokine, secreted by skeletal muscle in response to exercise, have been shown to mediate beneficial effects of exercise in many disorders. In the current study, we demonstrated that irisin promotes osteoblast proliferation, and increases the expression of osteoblastic transcription regulators, such as Runt-related transcription factor-2, osterix/sp7; and osteoblast differentiation markers, including alkaline phosphatase, collagen type 1 alpha-1, osteocalcin, and osteopontin in vitro. Irisin also increase ALP activity and calcium deposition in cultured osteoblast. These osteogenic effects were mediated by activating the p38 mitogen-activated protein kinase (p-p38 MAPK) and extracellular signal-regulated kinase (ERK). Inhibition of p38 MAPK by SB023580 or pERK by U0126 abolished the proliferation and up-regulatory effects of irisin on Runx2 expression and ALP activity. Together our observation suggest that irisin directly targets osteoblast, promoting osteoblast proliferation and differentiation via activating P38/ERK MAP kinase signaling cascades in vitro. Whether irisin can be utilized as the therapeutic agents for osteopenia and osteoporosis is worth to be further pursued. PMID:26738434

  18. Beclin 1 regulates growth factor receptor signaling in breast cancer.

    PubMed

    Rohatgi, R A; Janusis, J; Leonard, D; Bellvé, K D; Fogarty, K E; Baehrecke, E H; Corvera, S; Shaw, L M

    2015-10-16

    Beclin 1 is a haploinsufficient tumor suppressor that is decreased in many human tumors. The function of beclin 1 in cancer has been attributed primarily to its role in the degradative process of macroautophagy. However, beclin 1 is a core component of the vacuolar protein sorting 34 (Vps34)/class III phosphatidylinositoI-3 kinase (PI3KC3) and Vps15/p150 complex that regulates multiple membrane-trafficking events. In the current study, we describe an alternative mechanism of action for beclin 1 in breast cancer involving its control of growth factor receptor signaling. We identify a specific stage of early endosome maturation that is regulated by beclin 1, the transition of APPL1-containing phosphatidyIinositol 3-phosphate-negative (PI3P(-)) endosomes to PI3P(+) endosomes. Beclin 1 regulates PI3P production in response to growth factor stimulation to control the residency time of growth factor receptors in the PI3P(-)/APPL(+)-signaling-competent compartment. As a result, suppression of BECN1 sustains growth factor-stimulated AKT and ERK activation resulting in increased breast carcinoma cell invasion. In human breast tumors, beclin 1 expression is inversely correlated with AKT and ERK phosphorylation. Our data identify a novel role for beclin 1 in regulating growth factor signaling and reveal a mechanism by which loss of beclin 1 expression would enhance breast cancer progression.

  19. EIN2-directed translational regulation of ethylene signaling in Arabidopsis.

    PubMed

    Li, Wenyang; Ma, Mengdi; Feng, Ying; Li, Hongjiang; Wang, Yichuan; Ma, Yutong; Li, Mingzhe; An, Fengying; Guo, Hongwei

    2015-10-22

    Ethylene is a gaseous phytohormone that plays vital roles in plant growth and development. Previous studies uncovered EIN2 as an essential signal transducer linking ethylene perception on ER to transcriptional regulation in the nucleus through a "cleave and shuttle" model. In this study, we report another mechanism of EIN2-mediated ethylene signaling, whereby EIN2 imposes the translational repression of EBF1 and EBF2 mRNA. We find that the EBF1/2 3' UTRs mediate EIN2-directed translational repression and identify multiple poly-uridylates (PolyU) motifs as functional cis elements of 3' UTRs. Furthermore, we demonstrate that ethylene induces EIN2 to associate with 3' UTRs and target EBF1/2 mRNA to cytoplasmic processing-body (P-body) through interacting with multiple P-body factors, including EIN5 and PABs. Our study illustrates translational regulation as a key step in ethylene signaling and presents mRNA 3' UTR functioning as a "signal transducer" to sense and relay cellular signaling in plants. VIDEO ABSTRACT.

  20. Bmp signaling mediates endoderm pouch morphogenesis by regulating Fgf signaling in zebrafish.

    PubMed

    Lovely, C Ben; Swartz, Mary E; McCarthy, Neil; Norrie, Jacqueline L; Eberhart, Johann K

    2016-06-01

    The endodermal pouches are a series of reiterated structures that segment the pharyngeal arches and help pattern the vertebrate face. Multiple pathways regulate the complex process of endodermal development, including the Bone morphogenetic protein (Bmp) pathway. However, the role of Bmp signaling in pouch morphogenesis is poorly understood. Using genetic and chemical inhibitor approaches, we show that pouch morphogenesis requires Bmp signaling from 10-18 h post-fertilization, immediately following gastrulation. Blocking Bmp signaling during this window results in morphological defects to the pouches and craniofacial skeleton. Using genetic chimeras we show that Bmp signals directly to the endoderm for proper morphogenesis. Time-lapse imaging and analysis of reporter transgenics show that Bmp signaling is necessary for pouch outpocketing via the Fibroblast growth factor (Fgf) pathway. Double loss-of-function analyses demonstrate that Bmp and Fgf signaling interact synergistically in craniofacial development. Collectively, our analyses shed light on the tissue and signaling interactions that regulate development of the vertebrate face. PMID:27122171

  1. Regulation of PP2A by Sphingolipid Metabolism and Signaling

    PubMed Central

    Oaks, Joshua; Ogretmen, Besim

    2014-01-01

    Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase that is a primary regulator of cellular proliferation through targeting of proliferative kinases, cell cycle regulators, and apoptosis inhibitors. It is through the regulation of these regulatory elements that gives PP2A tumor suppressor functions. In addition to mutations on the regulatory subunits, the phosphatase/tumor suppressing activity of PP2A is also inhibited in several cancer types due to overexpression or modification of the endogenous PP2A inhibitors such as SET/I2PP2A. This review focuses on the current literature regarding the interactions between the lipid signaling molecules, selectively sphingolipids, and the PP2A inhibitor SET for the regulation of PP2A, and the therapeutic potential of sphingolipids as PP2A activators for tumor suppression via targeting SET oncoprotein. PMID:25642418

  2. Regulators of G-protein-signaling proteins: negative modulators of G-protein-coupled receptor signaling.

    PubMed

    Woodard, Geoffrey E; Jardín, Isaac; Berna-Erro, A; Salido, Gines M; Rosado, Juan A

    2015-01-01

    Regulators of G-protein-signaling (RGS) proteins are a category of intracellular proteins that have an inhibitory effect on the intracellular signaling produced by G-protein-coupled receptors (GPCRs). RGS along with RGS-like proteins switch on through direct contact G-alpha subunits providing a variety of intracellular functions through intracellular signaling. RGS proteins have a common RGS domain that binds to G alpha. RGS proteins accelerate GTPase and thus enhance guanosine triphosphate hydrolysis through the alpha subunit of heterotrimeric G proteins. As a result, they inactivate the G protein and quickly turn off GPCR signaling thus terminating the resulting downstream signals. Activity and subcellular localization of RGS proteins can be changed through covalent molecular changes to the enzyme, differential gene splicing, and processing of the protein. Other roles of RGS proteins have shown them to not be solely committed to being inhibitors but behave more as modulators and integrators of signaling. RGS proteins modulate the duration and kinetics of slow calcium oscillations and rapid phototransduction and ion signaling events. In other cases, RGS proteins integrate G proteins with signaling pathways linked to such diverse cellular responses as cell growth and differentiation, cell motility, and intracellular trafficking. Human and animal studies have revealed that RGS proteins play a vital role in physiology and can be ideal targets for diseases such as those related to addiction where receptor signaling seems continuously switched on.

  3. Regulation of PCP by the Fat signaling pathway

    PubMed Central

    Matis, Maja; Axelrod, Jeffrey D.

    2013-01-01

    Planar cell polarity (PCP) in epithelia, orthogonal to the apical–basal axis, is essential for numerous developmental events and physiological functions. Drosophila model systems have been at the forefront of studies revealing insights into mechanisms regulating PCP and have revealed distinct signaling modules. One of these, involving the atypical cadherins Fat and Dachsous and the ectokinase Four-jointed, appears to link the direction of cell polarization to the tissue axes. We discuss models for the function of this signaling module as well as several unanswered questions that may guide future investigations. PMID:24142873

  4. Insulin signalling and the regulation of glucose and lipid metabolism

    NASA Astrophysics Data System (ADS)

    Saltiel, Alan R.; Kahn, C. Ronald

    2001-12-01

    The epidemic of type 2 diabetes and impaired glucose tolerance is one of the main causes of morbidity and mortality worldwide. In both disorders, tissues such as muscle, fat and liver become less responsive or resistant to insulin. This state is also linked to other common health problems, such as obesity, polycystic ovarian disease, hyperlipidaemia, hypertension and atherosclerosis. The pathophysiology of insulin resistance involves a complex network of signalling pathways, activated by the insulin receptor, which regulates intermediary metabolism and its organization in cells. But recent studies have shown that numerous other hormones and signalling events attenuate insulin action, and are important in type 2 diabetes.

  5. Merlin, a regulator of Hippo signaling, regulates Wnt/β-catenin signaling

    PubMed Central

    Kim, Soyoung; Jho, Eek-hoon

    2016-01-01

    Merlin, encoded by the NF2 gene, is a tumor suppressor that exerts its function via inhibiting mitogenic receptors at the plasma membrane. Although multiple mutations in Merlin have been identified in Neurofibromatosis type II (NF2) disease, its molecular mechanism is not fully understood. Here, we show that Merlin interacts with LRP6 and inhibits LRP6 phosphorylation, a critical step for the initiation of Wnt signaling. We found that treatment of Wnt3a caused phosphorylation of Merlin by PAK1, leading to detachment of Merlin from LRP6 and allowing the initiation of Wnt/β-catenin signaling. A higher level of β-catenin was found in tissues from NF2 patients. Enhanced proliferation and migration caused by knockdown of Merlin in glioblastoma cells were inhibited by suppression of β-catenin. Conclusively, these results suggest that sustained Wnt/β-catenin signaling activity induced by abrogation of Merlin-mediated inhibition of LRP6 phosphorylation might be a cause of NF2 disease. [BMB Reports 2016; 49(7): 357-358] PMID:27345717

  6. MAP Support Detection for Greedy Sparse Signal Recovery Algorithms in Compressive Sensing

    NASA Astrophysics Data System (ADS)

    Lee, Namyoon

    2016-10-01

    A reliable support detection is essential for a greedy algorithm to reconstruct a sparse signal accurately from compressed and noisy measurements. This paper proposes a novel support detection method for greedy algorithms, which is referred to as "\\textit{maximum a posteriori (MAP) support detection}". Unlike existing support detection methods that identify support indices with the largest correlation value in magnitude per iteration, the proposed method selects them with the largest likelihood ratios computed under the true and null support hypotheses by simultaneously exploiting the distributions of sensing matrix, sparse signal, and noise. Leveraging this technique, MAP-Matching Pursuit (MAP-MP) is first presented to show the advantages of exploiting the proposed support detection method, and a sufficient condition for perfect signal recovery is derived for the case when the sparse signal is binary. Subsequently, a set of iterative greedy algorithms, called MAP-generalized Orthogonal Matching Pursuit (MAP-gOMP), MAP-Compressive Sampling Matching Pursuit (MAP-CoSaMP), and MAP-Subspace Pursuit (MAP-SP) are presented to demonstrate the applicability of the proposed support detection method to existing greedy algorithms. From empirical results, it is shown that the proposed greedy algorithms with highly reliable support detection can be better, faster, and easier to implement than basis pursuit via linear programming.

  7. Protein Kinase C and Extracellular Signal-Regulated Kinase Regulate Movement, Attachment, Pairing and Egg Release in Schistosoma mansoni

    PubMed Central

    Ressurreição, Margarida; De Saram, Paulu; Kirk, Ruth S.; Rollinson, David; Emery, Aidan M.; Page, Nigel M.; Davies, Angela J.; Walker, Anthony J.

    2014-01-01

    Protein kinases C (PKCs) and extracellular signal-regulated kinases (ERKs) are evolutionary conserved cell signalling enzymes that coordinate cell function. Here we have employed biochemical approaches using ‘smart’ antibodies and functional screening to unravel the importance of these enzymes to Schistosoma mansoni physiology. Various PKC and ERK isotypes were detected, and were differentially phosphorylated (activated) throughout the various S. mansoni life stages, suggesting isotype-specific roles and differences in signalling complexity during parasite development. Functional kinase mapping in adult worms revealed that activated PKC and ERK were particularly associated with the adult male tegument, musculature and oesophagus and occasionally with the oesophageal gland; other structures possessing detectable activated PKC and/or ERK included the Mehlis' gland, ootype, lumen of the vitellaria, seminal receptacle and excretory ducts. Pharmacological modulation of PKC and ERK activity in adult worms using GF109203X, U0126, or PMA, resulted in significant physiological disturbance commensurate with these proteins occupying a central position in signalling pathways associated with schistosome muscular activity, neuromuscular coordination, reproductive function, attachment and pairing. Increased activation of ERK and PKC was also detected in worms following praziquantel treatment, with increased signalling associated with the tegument and excretory system and activated ERK localizing to previously unseen structures, including the cephalic ganglia. These findings support roles for PKC and ERK in S. mansoni homeostasis, and identify these kinase groups as potential targets for chemotherapeutic treatments against human schistosomiasis, a neglected tropical disease of enormous public health significance. PMID:24921927

  8. Redox signaling regulated by electrophiles and reactive sulfur species.

    PubMed

    Nishida, Motohiro; Kumagai, Yoshito; Ihara, Hideshi; Fujii, Shigemoto; Motohashi, Hozumi; Akaike, Takaaki

    2016-03-01

    Redox signaling is a key modulator of oxidative stress induced by nonspecific insults of biological molecules generated by reactive oxygen species. Current redox biology is revisiting the traditional concept of oxidative stress, such that toxic effects of reactive oxygen species are protected by diverse antioxidant systems upregulated by oxidative stress responses that are physiologically mediated by redox-dependent cell signaling pathways. Redox signaling is thus precisely regulated by endogenous electrophilic substances that are generated from reactive oxygen species and nitric oxide and its derivative reactive species during stress responses. Among electrophiles formed endogenously, 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP) has unique cell signaling functions, and pathways for its biosynthesis, signaling mechanism, and metabolism in cells have been clarified. Reactive sulfur species such as cysteine hydropersulfides that are abundant in cells are likely involved in 8-nitro-cGMP metabolism. These new aspects of redox biology may stimulate innovative and multidisciplinary research in cell and stem cell biology; infectious diseases, cancer, metabolic syndrome, ageing, and neurodegenerative diseases; and other oxidative stress-related disorders. This review focuses on the most recent progress in the biosynthesis, cell signaling, and metabolism of 8-nitro-cGMP, which is a likely target for drug development and lead to discovery of novel therapeutics for many diseases. PMID:27013774

  9. Redox signaling regulated by electrophiles and reactive sulfur species

    PubMed Central

    Nishida, Motohiro; Kumagai, Yoshito; Ihara, Hideshi; Fujii, Shigemoto; Motohashi, Hozumi; Akaike, Takaaki

    2016-01-01

    Redox signaling is a key modulator of oxidative stress induced by nonspecific insults of biological molecules generated by reactive oxygen species. Current redox biology is revisiting the traditional concept of oxidative stress, such that toxic effects of reactive oxygen species are protected by diverse antioxidant systems upregulated by oxidative stress responses that are physiologically mediated by redox-dependent cell signaling pathways. Redox signaling is thus precisely regulated by endogenous electrophilic substances that are generated from reactive oxygen species and nitric oxide and its derivative reactive species during stress responses. Among electrophiles formed endogenously, 8-nitroguanosine 3',5'-cyclic monophosphate (8-nitro-cGMP) has unique cell signaling functions, and pathways for its biosynthesis, signaling mechanism, and metabolism in cells have been clarified. Reactive sulfur species such as cysteine hydropersulfides that are abundant in cells are likely involved in 8-nitro-cGMP metabolism. These new aspects of redox biology may stimulate innovative and multidisciplinary research in cell and stem cell biology; infectious diseases, cancer, metabolic syndrome, ageing, and neurodegenerative diseases; and other oxidative stress-related disorders. This review focuses on the most recent progress in the biosynthesis, cell signaling, and metabolism of 8-nitro-cGMP, which is a likely target for drug development and lead to discovery of novel therapeutics for many diseases. PMID:27013774

  10. Larynx carcinoma regulates tumor-associated macrophages through PLGF signaling

    PubMed Central

    Zhou, Xu; Qi, Ying

    2015-01-01

    Cancer neovascularization plays an essential role in the metastasis of larynx carcinoma (LC). However, the underlying molecular mechanisms are not completely understood. Recently, we reported that placental growth factor (PLGF) regulates expression of matrix metalloproteinase 3 (MMP3) through ERK/MAPK signaling pathway in LC. Here, we show that MMP9 upregulated in LC, and appeared to be mainly produced by M2 macrophages (tumor-associated macrophages (TAM)). In a transwell co-culture system, PLGF secreted by LC cells triggered macrophage polarization to a TAM subtype that releases MMP9. Moreover, MMP9 was found to be activated in the PLGF-polarized TAM via transforming growth factor β (TGFβ) receptor signaling activation. Furthermore, PLGF in LC cells induced macrophage polarization in vivo, and significantly promoted the growth of LC. Thus, together with our previous work, our study highlights a pivotal role of cross-talk between TAM and LC in regulating the metastasis of LC. PMID:25961789

  11. MAPK/JNK signalling: a potential autophagy regulation pathway

    PubMed Central

    Zhou, Yuan-Yuan; Li, Ying; Jiang, Wei-Qin; Zhou, Lin-Fu

    2015-01-01

    Autophagy refers to a lysosomal degradative pathway or a process of self-cannibalization. This pathway maintains nutrients levels for vital cellular functions during periods of starvation and it provides cells with survival advantages under various stress situations. However, the mechanisms responsible for the induction and regulation of autophagy are poorly understood. The c-Jun NH2-terminal kinase (JNK) signal transduction pathway functions to induce defence mechanisms that protect organisms against acute oxidative and xenobiotic insults. This pathway has also been repeatedly linked to the molecular events involved in autophagy regulation. The present review will focus on recent advances in understanding of the relationship between mitogen-activated protein kinase (MAPK)/JNK signalling and autophagic cell death. PMID:26182361

  12. Cellular redox regulation, signaling, and stress response in plants.

    PubMed

    Shigeoka, Shigeru; Maruta, Takanori

    2014-01-01

    Cellular and organellar redox states, which are characterized by the balance between oxidant and antioxidant pool sizes, play signaling roles in the regulation of gene expression and protein function in a wide variety of plant physiological processes including stress acclimation. Reactive oxygen species (ROS) and ascorbic acid (AsA) are the most abundant oxidants and antioxidants, respectively, in plant cells; therefore, the metabolism of these redox compounds must be strictly and spatiotemporally controlled. In this review, we provided an overview of our previous studies as well as recent advances in (1) the molecular mechanisms and regulation of AsA biosynthesis, (2) the molecular and genetic properties of ascorbate peroxidases, and (3) stress acclimation via ROS-derived oxidative/redox signaling pathways, and discussed future perspectives in this field.

  13. Metabolic control of signalling pathways and metabolic auto-regulation.

    PubMed

    Lorendeau, Doriane; Christen, Stefan; Rinaldi, Gianmarco; Fendt, Sarah-Maria

    2015-08-01

    Metabolic alterations have emerged as an important hallmark in the development of various diseases. Thus, understanding the complex interplay of metabolism with other cellular processes such as cell signalling is critical to rationally control and modulate cellular physiology. Here, we review in the context of mammalian target of rapamycin, AMP-activated protein kinase and p53, the orchestrated interplay between metabolism and cellular signalling as well as transcriptional regulation. Moreover, we discuss recent discoveries in auto-regulation of metabolism (i.e. how metabolic parameters such as metabolite levels activate or inhibit enzymes and thus metabolic pathways). Finally, we review functional consequences of post-translational modification on metabolic enzyme abundance and/or activities.

  14. Circadian regulation of hormone signaling and plant physiology.

    PubMed

    Atamian, Hagop S; Harmer, Stacey L

    2016-08-01

    The survival and reproduction of plants depend on their ability to cope with a wide range of daily and seasonal environmental fluctuations during their life cycle. Phytohormones are plant growth regulators that are involved in almost every aspect of growth and development as well as plant adaptation to myriad abiotic and biotic conditions. The circadian clock, an endogenous and cell-autonomous biological timekeeper that produces rhythmic outputs with close to 24-h rhythms, provides an adaptive advantage by synchronizing plant physiological and metabolic processes to the external environment. The circadian clock regulates phytohormone biosynthesis and signaling pathways to generate daily rhythms in hormone activity that fine-tune a range of plant processes, enhancing adaptation to local conditions. This review explores our current understanding of the interplay between the circadian clock and hormone signaling pathways.

  15. ASK1 signalling regulates brown and beige adipocyte function

    PubMed Central

    Hattori, Kazuki; Naguro, Isao; Okabe, Kohki; Funatsu, Takashi; Furutani, Shotaro; Takeda, Kohsuke; Ichijo, Hidenori

    2016-01-01

    Recent studies suggest that adult humans have active brown or beige adipocytes, the activation of which might be a therapeutic strategy for the treatment of diverse metabolic diseases. Here we show that the protein kinase ASK1 regulates brown and beige adipocytes function. In brown or white adipocytes, the PKA-ASK1-p38 axis is activated in response to cAMP signalling and contributes to the cell-autonomous induction of genes, including Ucp1. Global and fat-specific ASK1 deficiency leads to impaired metabolic responses, including thermogenesis and oxygen consumption, at the cell and whole-body levels, respectively. Our data thus indicate that the ASK1 signalling axis is a regulator of brown and beige adipocyte gene expression and function. PMID:27045525

  16. JAK/Stat signaling regulates heart precursor diversification in Drosophila

    PubMed Central

    Johnson, Aaron N.; Mokalled, Mayssa H.; Haden, Tom N.; Olson, Eric N.

    2011-01-01

    Intercellular signal transduction pathways regulate the NK-2 family of transcription factors in a conserved gene regulatory network that directs cardiogenesis in both flies and mammals. The Drosophila NK-2 protein Tinman (Tin) was recently shown to regulate Stat92E, the Janus kinase (JAK) and Signal transducer and activator of transcription (Stat) pathway effector, in the developing mesoderm. To understand whether the JAK/Stat pathway also regulates cardiogenesis, we performed a systematic characterization of JAK/Stat signaling during mesoderm development. Drosophila embryos with mutations in the JAK/Stat ligand upd or in Stat92E have non-functional hearts with luminal defects and inappropriate cell aggregations. Using strong Stat92E loss-of-function alleles, we show that the JAK/Stat pathway regulates tin expression prior to heart precursor cell diversification. tin expression can be subdivided into four phases and, in Stat92E mutant embryos, the broad phase 2 expression pattern in the dorsal mesoderm does not restrict to the constrained phase 3 pattern. These embryos also have an expanded pericardial cell domain. We show the E(spl)-C gene HLHm5 is expressed in a pattern complementary to tin during phase 3 and that this expression is JAK/Stat dependent. In addition, E(spl)-C mutant embryos phenocopy the cardiac defects of Stat92E embryos. Mechanistically, JAK/Stat signals activate E(spl)-C genes to restrict Tin expression and the subsequent expression of the T-box transcription factor H15 to direct heart precursor diversification. This study is the first to characterize a role for the JAK/Stat pathway during cardiogenesis and identifies an autoregulatory circuit in which tin limits its own expression domain. PMID:21965617

  17. Regulation of Interferon Gamma Signaling by Suppressors of Cytokine Signaling and Regulatory T Cells

    PubMed Central

    Larkin, Joseph; Ahmed, Chulbul M.; Wilson, Tenisha D.; Johnson, Howard M.

    2013-01-01

    Regulatory T cells (Tregs) play an indispensable role in the prevention of autoimmune disease, as interferon gamma (IFNγ) mediated, lethal auto-immunity occurs (in both mice and humans) in their absence. In addition, Tregs have been implicated in preventing the onset of autoimmune and auto-inflammatory conditions associated with aberrant IFNγ signaling such as type 1 diabetes, lupus, and lipopolysaccharide (LPS) mediated endotoxemia. Notably, suppressor of cytokine signaling-1 deficient (SOCS1−/−) mice also succumb to a lethal auto-inflammatory disease, dominated by excessive IFNγ signaling and bearing similar disease course kinetics to Treg deficient mice. Moreover SOCS1 deficiency has been implicated in lupus progression, and increased susceptibility to LPS mediated endotoxemia. Although it has been established that Tregs and SOCS1 play a critical role in the regulation of IFNγ signaling, and the prevention of lethal auto-inflammatory disease, the role of Treg/SOCS1 cross-talk in the regulation of IFNγ signaling has been essentially unexplored. This is especially pertinent as recent publications have implicated a role of SOCS1 in the stability of peripheral Tregs. This review will examine the emerging research findings implicating a critical role of the intersection of the SOCS1 and Treg regulatory pathways in the control of IFN gamma signaling and immune system function. PMID:24391643

  18. Regulation of IGF -1 signaling by microRNAs

    PubMed Central

    Jung, Hwa Jin; Suh, Yousin

    2014-01-01

    The insulin-like growth factor 1 (IGF-1) signaling pathway regulates critical biological processes including development, homeostasis, and aging. Dysregulation of this pathway has been implicated in a myriad of diseases such as cancers, neurodegenerative diseases, and metabolic disorders, making the IGF-1 signaling pathway a prime target to develop therapeutic and intervention strategies. Recently, small non-coding RNA molecules in ∼22 nucleotide length, microRNAs (miRNAs), have emerged as a new regulator of biological processes in virtually all organ systems and increasing studies are linking altered miRNA function to disease mechanisms. A miRNA binds to 3’UTRs of multiple target genes and coordinately downregulates their expression, thereby exerting a profound influence on gene regulatory networks. Here we review the components of the IGF-1 signaling pathway that are known targets of miRNA regulation, and highlight recent studies that suggest therapeutic potential of these miRNAs against various diseases. PMID:25628647

  19. Cannabinoid receptor signaling regulates liver development and metabolism.

    PubMed

    Liu, Leah Y; Alexa, Kristen; Cortes, Mauricio; Schatzman-Bone, Stephanie; Kim, Andrew J; Mukhopadhyay, Bani; Cinar, Resat; Kunos, George; North, Trista E; Goessling, Wolfram

    2016-02-15

    Endocannabinoid (EC) signaling mediates psychotropic effects and regulates appetite. By contrast, potential roles in organ development and embryonic energy consumption remain unknown. Here, we demonstrate that genetic or chemical inhibition of cannabinoid receptor (Cnr) activity disrupts liver development and metabolic function in zebrafish (Danio rerio), impacting hepatic differentiation, but not endodermal specification: loss of cannabinoid receptor 1 (cnr1) and cnr2 activity leads to smaller livers with fewer hepatocytes, reduced liver-specific gene expression and proliferation. Functional assays reveal abnormal biliary anatomy and lipid handling. Adult cnr2 mutants are susceptible to hepatic steatosis. Metabolomic analysis reveals reduced methionine content in Cnr mutants. Methionine supplementation rescues developmental and metabolic defects in Cnr mutant livers, suggesting a causal relationship between EC signaling, methionine deficiency and impaired liver development. The effect of Cnr on methionine metabolism is regulated by sterol regulatory element-binding transcription factors (Srebfs), as their overexpression rescues Cnr mutant liver phenotypes in a methionine-dependent manner. Our work describes a novel developmental role for EC signaling, whereby Cnr-mediated regulation of Srebfs and methionine metabolism impacts liver development and function.

  20. Axin Regulates Dendritic Spine Morphogenesis through Cdc42-Dependent Signaling

    PubMed Central

    Chen, Yu; Liang, Zhuoyi; Fei, Erkang; Chen, Yuewen; Zhou, Xiaopu; Fang, Weiqun; Fu, Wing-Yu; Fu, Amy K. Y.; Ip, Nancy Y.

    2015-01-01

    During development, scaffold proteins serve as important platforms for orchestrating signaling complexes to transduce extracellular stimuli into intracellular responses that regulate dendritic spine morphology and function. Axin (“axis inhibitor”) is a key scaffold protein in canonical Wnt signaling that interacts with specific synaptic proteins. However, the cellular functions of these protein–protein interactions in dendritic spine morphology and synaptic regulation are unclear. Here, we report that Axin protein is enriched in synaptic fractions, colocalizes with the postsynaptic marker PSD-95 in cultured hippocampal neurons, and interacts with a signaling protein Ca2+/calmodulin-dependent protein kinase II (CaMKII) in synaptosomal fractions. Axin depletion by shRNA in cultured neurons or intact hippocampal CA1 regions significantly reduced dendritic spine density. Intriguingly, the defective dendritic spine morphogenesis in Axin-knockdown neurons could be restored by overexpression of the small Rho-GTPase Cdc42, whose activity is regulated by CaMKII. Moreover, pharmacological stabilization of Axin resulted in increased dendritic spine number and spontaneous neurotransmission, while Axin stabilization in hippocampal neurons reduced the elimination of dendritic spines. Taken together, our findings suggest that Axin promotes dendritic spine stabilization through Cdc42-dependent cytoskeletal reorganization. PMID:26204446

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

    SciTech Connect

    Cark, Steven E.

    2003-09-10

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

  2. Cytoskeletal Reorganization Drives Mesenchymal Condensation and Regulates Downstream Molecular Signaling.

    PubMed

    Ray, Poulomi; Chapman, Susan C

    2015-01-01

    Skeletal condensation occurs when specified mesenchyme cells self-organize over several days to form a distinctive cartilage template. Here, we determine how and when specified mesenchyme cells integrate mechanical and molecular information from their environment, forming cartilage condensations in the pharyngeal arches of chick embryos. By disrupting cytoskeletal reorganization, we demonstrate that dynamic cell shape changes drive condensation and modulate the response of the condensing cells to Fibroblast Growth Factor (FGF), Bone Morphogenetic Protein (BMP) and Transforming Growth Factor beta (TGF-β) signaling pathways. Rho Kinase (ROCK)-driven actomyosin contractions and Myosin II-generated differential cell cortex tension regulate these cell shape changes. Disruption of the condensation process inhibits the differentiation of the mesenchyme cells into chondrocytes, demonstrating that condensation regulates the fate of the mesenchyme cells. We also find that dorsal and ventral condensations undergo distinct cell shape changes. BMP signaling is instructive for dorsal condensation-specific cell shape changes. Moreover, condensations exhibit ventral characteristics in the absence of BMP signaling, suggesting that in the pharyngeal arches ventral morphology is the ground pattern. Overall, this study characterizes the interplay between cytoskeletal dynamics and molecular signaling in a self-organizing system during tissue morphogenesis.

  3. Cytoskeletal Reorganization Drives Mesenchymal Condensation and Regulates Downstream Molecular Signaling.

    PubMed

    Ray, Poulomi; Chapman, Susan C

    2015-01-01

    Skeletal condensation occurs when specified mesenchyme cells self-organize over several days to form a distinctive cartilage template. Here, we determine how and when specified mesenchyme cells integrate mechanical and molecular information from their environment, forming cartilage condensations in the pharyngeal arches of chick embryos. By disrupting cytoskeletal reorganization, we demonstrate that dynamic cell shape changes drive condensation and modulate the response of the condensing cells to Fibroblast Growth Factor (FGF), Bone Morphogenetic Protein (BMP) and Transforming Growth Factor beta (TGF-β) signaling pathways. Rho Kinase (ROCK)-driven actomyosin contractions and Myosin II-generated differential cell cortex tension regulate these cell shape changes. Disruption of the condensation process inhibits the differentiation of the mesenchyme cells into chondrocytes, demonstrating that condensation regulates the fate of the mesenchyme cells. We also find that dorsal and ventral condensations undergo distinct cell shape changes. BMP signaling is instructive for dorsal condensation-specific cell shape changes. Moreover, condensations exhibit ventral characteristics in the absence of BMP signaling, suggesting that in the pharyngeal arches ventral morphology is the ground pattern. Overall, this study characterizes the interplay between cytoskeletal dynamics and molecular signaling in a self-organizing system during tissue morphogenesis. PMID:26237312

  4. Endothelial HIF signaling regulates pulmonary fibrosis-associated pulmonary hypertension.

    PubMed

    Bryant, Andrew J; Carrick, Ryan P; McConaha, Melinda E; Jones, Brittany R; Shay, Sheila D; Moore, Christy S; Blackwell, Thomas R; Gladson, Santhi; Penner, Niki L; Burman, Ankita; Tanjore, Harikrishna; Hemnes, Anna R; Karwandyar, Ayub K; Polosukhin, Vasiliy V; Talati, Megha A; Dong, Hui-Jia; Gleaves, Linda A; Carrier, Erica J; Gaskill, Christa; Scott, Edward W; Majka, Susan M; Fessel, Joshua P; Haase, Volker H; West, James D; Blackwell, Timothy S; Lawson, William E

    2016-02-01

    Pulmonary hypertension (PH) complicating chronic parenchymal lung disease, such as idiopathic pulmonary fibrosis, results in significant morbidity and mortality. Since the hypoxia-inducible factor (HIF) signaling pathway is important for development of pulmonary hypertension in chronic hypoxia, we investigated whether HIF signaling in vascular endothelium regulates development of PH related to pulmonary fibrosis. We generated a transgenic model in which HIF is deleted within vascular endothelial cells and then exposed these mice to chronic intraperitoneal bleomycin to induce PH associated with lung fibrosis. Although no differences in the degree of fibrotic remodeling were observed, we found that endothelial HIF-deficient mice were protected against development of PH, including right ventricle and pulmonary vessel remodeling. Similarly, endothelial HIF-deficient mice were protected from PH after a 4-wk exposure to normobaric hypoxia. In vitro studies of pulmonary vascular endothelial cells isolated from the HIF-targeted mice and controls revealed that endothelial HIF signaling increases endothelial cell expression of connective tissue growth factor, enhances vascular permeability, and promotes pulmonary artery smooth muscle cell proliferation and wound healing ability, all of which have the potential to impact the development of PH in vivo. Taken together, these studies demonstrate that vascular endothelial cell HIF signaling is necessary for development of hypoxia and pulmonary fibrosis associated PH. As such, HIF and HIF-regulated targets represent a therapeutic target in these conditions.

  5. Platelet adhesion signalling and the regulation of thrombus formation.

    PubMed

    Gibbins, Jonathan M

    2004-07-15

    Platelets perform a central role in haemostasis and thrombosis. They adhere to subendothelial collagens exposed at sites of blood vessel injury via the glycoprotein (GP) Ib-V-IX receptor complex, GPVI and integrin alpha(2)beta(1). These receptors perform distinct functions in the regulation of cell signalling involving non-receptor tyrosine kinases (e.g. Src, Fyn, Lyn, Syk and Btk), adaptor proteins, phospholipase C and lipid kinases such as phosphoinositide 3-kinase. They are also coupled to an increase in cytosolic calcium levels and protein kinase C activation, leading to the secretion of paracrine/autocrine platelet factors and an increase in integrin receptor affinities. Through the binding of plasma fibrinogen and von Willebrand Factor to integrin alpha(IIb)beta(3), a platelet thrombus is formed. Although increasing evidence indicates that each of the adhesion receptors GPIb-V-IX and GPVI and integrins alpha(2)beta(1) and alpha(IIb)beta(3) contribute to the signalling that regulates this process, the individual roles of each are only beginning to be dissected. By contrast, adhesion receptor signalling through platelet endothelial cell adhesion molecule 1 (PECAM-1) is implicated in the inhibition of platelet function and thrombus formation in the healthy circulation. Recent studies indicate that understanding of platelet adhesion signalling mechanisms might enable the development of new strategies to treat and prevent thrombosis. PMID:15252124

  6. Insulin signaling regulates neurite growth during metamorphic neuronal remodeling.

    PubMed

    Gu, Tingting; Zhao, Tao; Hewes, Randall S

    2014-01-15

    Although the growth capacity of mature neurons is often limited, some neurons can shift through largely unknown mechanisms from stable maintenance growth to dynamic, organizational growth (e.g. to repair injury, or during development transitions). During insect metamorphosis, many terminally differentiated larval neurons undergo extensive remodeling, involving elimination of larval neurites and outgrowth and elaboration of adult-specific projections. Here, we show in the fruit fly, Drosophila melanogaster (Meigen), that a metamorphosis-specific increase in insulin signaling promotes neuronal growth and axon branching after prolonged stability during the larval stages. FOXO, a negative effector in the insulin signaling pathway, blocked metamorphic growth of peptidergic neurons that secrete the neuropeptides CCAP and bursicon. RNA interference and CCAP/bursicon cell-targeted expression of dominant-negative constructs for other components of the insulin signaling pathway (InR, Pi3K92E, Akt1, S6K) also partially suppressed the growth of the CCAP/bursicon neuron somata and neurite arbor. In contrast, expression of wild-type or constitutively active forms of InR, Pi3K92E, Akt1, Rheb, and TOR, as well as RNA interference for negative regulators of insulin signaling (PTEN, FOXO), stimulated overgrowth. Interestingly, InR displayed little effect on larval CCAP/bursicon neuron growth, in contrast to its strong effects during metamorphosis. Manipulations of insulin signaling in many other peptidergic neurons revealed generalized growth stimulation during metamorphosis, but not during larval development. These findings reveal a fundamental shift in growth control mechanisms when mature, differentiated neurons enter a new phase of organizational growth. Moreover, they highlight strong evolutionarily conservation of insulin signaling in neuronal growth regulation.

  7. Crosstalk between mitochondrial stress signals regulates yeast chronological lifespan.

    PubMed

    Schroeder, Elizabeth A; Shadel, Gerald S

    2014-01-01

    Mitochondrial DNA (mtDNA) exists in multiple copies per cell and is essential for oxidative phosphorylation. Depleted or mutated mtDNA promotes numerous human diseases and may contribute to aging. Reduced TORC1 signaling in the budding yeast, Saccharomyces cerevisiae, extends chronological lifespan (CLS) in part by generating a mitochondrial ROS (mtROS) signal that epigenetically alters nuclear gene expression. To address the potential requirement for mtDNA maintenance in this response, we analyzed strains lacking the mitochondrial base-excision repair enzyme Ntg1p. Extension of CLS by mtROS signaling and reduced TORC1 activity, but not caloric restriction, was abrogated in ntg1Δ strains that exhibited mtDNA depletion without defects in respiration. The DNA damage response (DDR) kinase Rad53p, which transduces pro-longevity mtROS signals, is also activated in ntg1Δ strains. Restoring mtDNA copy number alleviated Rad53p activation and re-established CLS extension following mtROS signaling, indicating that Rad53p senses mtDNA depletion directly. Finally, DDR kinases regulate nucleus-mitochondria localization dynamics of Ntg1p. From these results, we conclude that the DDR pathway senses and may regulate Ntg1p-dependent mtDNA stability. Furthermore, Rad53p senses multiple mitochondrial stresses in a hierarchical manner to elicit specific physiological outcomes, exemplified by mtDNA depletion overriding the ability of Rad53p to transduce an adaptive mtROS longevity signal.

  8. Crosstalk between mitochondrial stress signals regulates yeast chronological lifespan

    PubMed Central

    Schroeder, Elizabeth A.; Shadel, Gerald S.

    2014-01-01

    Mitochondrial DNA (mtDNA) exists in multiple copies per cell and is essential for oxidative phosphorylation. Depleted or mutated mtDNA promotes numerous human diseases and may contribute to aging. Reduced TORC1 signaling in the budding yeast, Saccharomyces cerevisiae, extends chronological lifespan (CLS) in part by generating a mitochondrial ROS (mtROS) signal that epigenetically alters nuclear gene expression. To address the potential requirement for mtDNA maintenance in this response, we analyzed strains lacking the mitochondrial base-excision repair enzyme Ntg1p. Extension of CLS by mtROS signaling and reduced TORC1 activity, but not caloric restriction, was abrogated in ntg1Δ strains that exhibited mtDNA depletion without defects in respiration. The DNA damage response (DDR) kinase Rad53p, which transduces pro-longevity mtROS signals, is also activated in ntg1Δ strains. Restoring mtDNA copy number alleviated Rad53p activation and re-established CLS extension mtROS-mediated longevity signaling, indicating that Rad53p senses mtDNA depletion directly. Finally, DDR kinases regulate nucleus-mitochondria localization dynamics of Ntg1p. From these results, we conclude that the DDR pathway senses mtDNA instability and regulates Ntg1p in response. Furthermore, Rad53p senses multiple mitochondrial stresses in a hierarchical manner to elicit specific physiological outcomes, exemplified by mtDNA depletion overriding the ability of Rad53p to transduce an adaptive mtROS longevity signal. PMID:24373996

  9. Exploitation of latent allostery enables the evolution of new modes of MAP kinase regulation.

    PubMed

    Coyle, Scott M; Flores, Jonathan; Lim, Wendell A

    2013-08-15

    Allosteric interactions provide precise spatiotemporal control over signaling proteins, but how allosteric activators and their targets coevolve is poorly understood. Here, we trace the evolution of two allosteric activator motifs within the yeast scaffold protein Ste5 that specifically target the mating MAP kinase Fus3. One activator (Ste5-VWA) provides pathway insulation and dates to the divergence of Fus3 from its paralog, Kss1; a second activator (Ste5-FBD) that tunes mating behavior is, in contrast, not conserved in most lineages. Surprisingly, both Ste5 activator motifs could regulate MAP kinases that diverged from Fus3 prior to the emergence of Ste5, suggesting that Ste5 activators arose by exploiting latent regulatory features already present in the MAPK ancestor. The magnitude of this latent allosteric potential drifts widely among pre-Ste5 MAP kinases, providing a pool of hidden phenotypic diversity that, when revealed by new activators, could lead to functional divergence and to the evolution of distinct signaling behaviors. PMID:23953117

  10. Exploitation of latent protein allostery enables the evolution of novel and divergent MAP kinase regulation

    PubMed Central

    Coyle, Scott M.; Flores, Jonathan; Lim, Wendell A.

    2013-01-01

    SUMMARY Allosteric interactions provide precise spatiotemporal control over signaling proteins, but how allosteric activators and their targets co-evolve is poorly understood. Here, we trace the evolution of two allosteric activator motifs within the yeast scaffold protein Ste5 that specifically target the mating MAP kinase Fus3. One activator (Ste5-VWA) provides pathway insulation and dates to the divergence of Fus3 from its paralog, Kss1; a second activator (Ste5-FBD) that tunes mating behavior is, in contrast, not conserved in most lineages. Surprisingly, both Ste5 activator motifs could regulate MAP kinases that diverged from Fus3 prior to the emergence of Ste5, suggesting that Ste5 activators arose by exploiting latent regulatory features already present in the MAPK ancestor. The magnitude of this latent allosteric potential drifts widely among pre-Ste5 MAP kinases, providing a pool of hidden phenotypic diversity that, when revealed by new activators, could lead to functional divergence and the evolution of distinct signaling behaviors. PMID:23953117

  11. BAFF activation of the ERK5 MAP kinase pathway regulates B cell survival.

    PubMed

    Jacque, Emilie; Schweighoffer, Edina; Tybulewicz, Victor L J; Ley, Steven C

    2015-06-01

    B cell activating factor (BAFF) stimulation of the BAFF receptor (BAFF-R) is essential for the homeostatic survival of mature B cells. Earlier in vitro experiments with inhibitors that block MEK 1 and 2 suggested that activation of ERK 1 and 2 MAP kinases is required for BAFF-R to promote B cell survival. However, these inhibitors are now known to also inhibit MEK5, which activates the related MAP kinase ERK5. In the present study, we demonstrated that BAFF-induced B cell survival was actually independent of ERK1/2 activation but required ERK5 activation. Consistent with this, we showed that conditional deletion of ERK5 in B cells led to a pronounced global reduction in mature B2 B cell numbers, which correlated with impaired survival of ERK5-deficient B cells after BAFF stimulation. ERK5 was required for optimal BAFF up-regulation of Mcl1 and Bcl2a1, which are prosurvival members of the Bcl-2 family. However, ERK5 deficiency did not alter BAFF activation of the PI3-kinase-Akt or NF-κB signaling pathways, which are also important for BAFF to promote mature B cell survival. Our study reveals a critical role for the MEK5-ERK5 MAP kinase signaling pathway in BAFF-induced mature B cell survival and homeostatic maintenance of B2 cell numbers.

  12. 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

  13. Hedgehog Signaling Regulates the Survival of Gastric Cancer Cells by Regulating the Expression of Bcl-2

    PubMed Central

    Han, Myoung-Eun; Lee, Young-Suk; Baek, Sun-Yong; Kim, Bong-Seon; Kim, Jae-Bong; Oh, Sae-Ock

    2009-01-01

    Gastric cancer is the second most common cause of cancer deaths worldwide. The underlying molecular mechanisms of its carcinogenesis are relatively poorly characterized. Hedgehog (Hh) signaling, which is critical for development of various organs including the gastrointestinal tract, has been associated with gastric cancer. The present study was undertaken to reveal the underlying mechanism by which Hh signaling controls gastric cancer cell proliferation. Treatment of gastric cancer cells with cyclopamine, a specific inhibitor of Hh signaling pathway, reduced proliferation and induced apoptosis of gastric cancer cells. Cyclopamine treatment induced cytochrome c release from mitochondria and cleavage of caspase 9. Moreover, Bcl-2 expression was significantly reduced by cyclopamine treatment. These results suggest that Hh signaling regulates the survival of gastric cancer cells by regulating the expression of Bcl-2. PMID:19742123

  14. Signal digitizing system and method based on amplitude-to-time optical mapping

    DOEpatents

    Chou, Jason; Bennett, Corey V; Hernandez, Vince

    2015-01-13

    A signal digitizing system and method based on analog-to-time optical mapping, optically maps amplitude information of an analog signal of interest first into wavelength information using an amplitude tunable filter (ATF) to impress spectral changes induced by the amplitude of the analog signal onto a carrier signal, i.e. a train of optical pulses, and next from wavelength information to temporal information using a dispersive element so that temporal information representing the amplitude information is encoded in the time domain in the carrier signal. Optical-to-electrical conversion of the optical pulses into voltage waveforms and subsequently digitizing the voltage waveforms into a digital image enables the temporal information to be resolved and quantized in the time domain. The digital image may them be digital signal processed to digitally reconstruct the analog signal based on the temporal information with high fidelity.

  15. Hedgehog Signaling Regulates Telomerase Reverse Transcriptase in Human Cancer Cells

    PubMed Central

    Mazumdar, Tapati; Sandhu, Ranjodh; Qadan, Maha; DeVecchio, Jennifer; Magloire, Victoria; Agyeman, Akwasi; Li, Bibo; Houghton, Janet A.

    2013-01-01

    The Hedgehog (HH) signaling pathway is critical for normal embryonic development, tissue patterning and cell differentiation. Aberrant HH signaling is involved in multiple human cancers. HH signaling involves a multi-protein cascade activating the GLI proteins that transcriptionally regulate HH target genes. We have previously reported that HH signaling is essential for human colon cancer cell survival and inhibition of this signal induces DNA damage and extensive cell death. Here we report that the HH/GLI axis regulates human telomerase reverse transcriptase (hTERT), which determines the replication potential of cancer cells. Suppression of GLI1/GLI2 functions by a C-terminus truncated GLI3 repressor mutant (GLI3R), or by GANT61, a pharmacological inhibitor of GLI1/GLI2, reduced hTERT protein expression in human colon cancer, prostate cancer and Glioblastoma multiforme (GBM) cell lines. Expression of an N-terminus deleted constitutively active mutant of GLI2 (GLI2ΔN) increased hTERT mRNA and protein expression and hTERT promoter driven luciferase activity in human colon cancer cells while GANT61 inhibited hTERT mRNA expression and hTERT promoter driven luciferase activity. Chromatin immunoprecipitation with GLI1 or GLI2 antibodies precipitated fragments of the hTERT promoter in human colon cancer cells, which was reduced upon exposure to GANT61. In contrast, expression of GLI1 or GLI2ΔN in non-malignant 293T cells failed to alter the levels of hTERT mRNA and protein, or hTERT promoter driven luciferase activity. Further, expression of GLI2ΔN increased the telomerase enzyme activity, which was reduced by GANT61 administration in human colon cancer, prostate cancer, and GBM cells. These results identify hTERT as a direct target of the HH signaling pathway, and reveal a previously unknown role of the HH/GLI axis in regulating the replication potential of cancer cells. These findings are of significance in understanding the important regulatory mechanisms that

  16. Paradoxical signaling regulates structural plasticity in dendritic spines.

    PubMed

    Rangamani, Padmini; Levy, Michael G; Khan, Shahid; Oster, George

    2016-09-01

    Transient spine enlargement (3- to 5-min timescale) is an important event associated with the structural plasticity of dendritic spines. Many of the molecular mechanisms associated with transient spine enlargement have been identified experimentally. Here, we use a systems biology approach to construct a mathematical model of biochemical signaling and actin-mediated transient spine expansion in response to calcium influx caused by NMDA receptor activation. We have identified that a key feature of this signaling network is the paradoxical signaling loop. Paradoxical components act bifunctionally in signaling networks, and their role is to control both the activation and the inhibition of a desired response function (protein activity or spine volume). Using ordinary differential equation (ODE)-based modeling, we show that the dynamics of different regulators of transient spine expansion, including calmodulin-dependent protein kinase II (CaMKII), RhoA, and Cdc42, and the spine volume can be described using paradoxical signaling loops. Our model is able to capture the experimentally observed dynamics of transient spine volume. Furthermore, we show that actin remodeling events provide a robustness to spine volume dynamics. We also generate experimentally testable predictions about the role of different components and parameters of the network on spine dynamics. PMID:27551076

  17. Localized JNK signaling regulates organ size during development

    PubMed Central

    Willsey, Helen Rankin; Zheng, Xiaoyan; Carlos Pastor-Pareja, José; Willsey, A Jeremy; Beachy, Philip A; Xu, Tian

    2016-01-01

    A fundamental question of biology is what determines organ size. Despite demonstrations that factors within organs determine their sizes, intrinsic size control mechanisms remain elusive. Here we show that Drosophila wing size is regulated by JNK signaling during development. JNK is active in a stripe along the center of developing wings, and modulating JNK signaling within this stripe changes organ size. This JNK stripe influences proliferation in a non-canonical, Jun-independent manner by inhibiting the Hippo pathway. Localized JNK activity is established by Hedgehog signaling, where Ci elevates dTRAF1 expression. As the dTRAF1 homolog, TRAF4, is amplified in numerous cancers, these findings provide a new mechanism for how the Hedgehog pathway could contribute to tumorigenesis, and, more importantly, provides a new strategy for cancer therapies. Finally, modulation of JNK signaling centers in developing antennae and legs changes their sizes, suggesting a more generalizable role for JNK signaling in developmental organ size control. DOI: http://dx.doi.org/10.7554/eLife.11491.001 PMID:26974344

  18. An Nfic-hedgehog signaling cascade regulates tooth root development.

    PubMed

    Liu, Yang; Feng, Jifan; Li, Jingyuan; Zhao, Hu; Ho, Thach-Vu; Chai, Yang

    2015-10-01

    Coordination between the Hertwig's epithelial root sheath (HERS) and apical papilla (AP) is crucial for proper tooth root development. The hedgehog (Hh) signaling pathway and Nfic are both involved in tooth root development; however, their relationship has yet to be elucidated. Here, we establish a timecourse of mouse molar root development by histological staining of sections, and we demonstrate that Hh signaling is active before and during root development in the AP and HERS using Gli1 reporter mice. The proper pattern of Hh signaling activity in the AP is crucial for the proliferation of dental mesenchymal cells, because either inhibition with Hh inhibitors or constitutive activation of Hh signaling activity in transgenic mice leads to decreased proliferation in the AP and shorter roots. Moreover, Hh activity is elevated in Nfic(-/-) mice, a root defect model, whereas RNA sequencing and in situ hybridization show that the Hh attenuator Hhip is downregulated. ChIP and RNAscope analyses suggest that Nfic binds to the promoter region of Hhip. Treatment of Nfic(-/-) mice with Hh inhibitor partially restores cell proliferation, AP growth and root development. Taken together, our results demonstrate that an Nfic-Hhip-Hh signaling pathway is crucial for apical papilla growth and proper root formation. This discovery provides insight into the molecular mechanisms regulating tooth root development.

  19. An Nfic-hedgehog signaling cascade regulates tooth root development

    PubMed Central

    Liu, Yang; Feng, Jifan; Li, Jingyuan; Zhao, Hu; Ho, Thach-Vu; Chai, Yang

    2015-01-01

    Coordination between the Hertwig's epithelial root sheath (HERS) and apical papilla (AP) is crucial for proper tooth root development. The hedgehog (Hh) signaling pathway and Nfic are both involved in tooth root development; however, their relationship has yet to be elucidated. Here, we establish a timecourse of mouse molar root development by histological staining of sections, and we demonstrate that Hh signaling is active before and during root development in the AP and HERS using Gli1 reporter mice. The proper pattern of Hh signaling activity in the AP is crucial for the proliferation of dental mesenchymal cells, because either inhibition with Hh inhibitors or constitutive activation of Hh signaling activity in transgenic mice leads to decreased proliferation in the AP and shorter roots. Moreover, Hh activity is elevated in Nfic−/− mice, a root defect model, whereas RNA sequencing and in situ hybridization show that the Hh attenuator Hhip is downregulated. ChIP and RNAscope analyses suggest that Nfic binds to the promoter region of Hhip. Treatment of Nfic−/− mice with Hh inhibitor partially restores cell proliferation, AP growth and root development. Taken together, our results demonstrate that an Nfic-Hhip-Hh signaling pathway is crucial for apical papilla growth and proper root formation. This discovery provides insight into the molecular mechanisms regulating tooth root development. PMID:26293299

  20. Light signaling and the phytohormonal regulation of shoot growth.

    PubMed

    Kurepin, Leonid V; Pharis, Richard P

    2014-12-01

    Shoot growth of dicot plants is rigorously controlled by the interactions of environmental cues with several groups of phytohormones. The signaling effects of light on shoot growth are of special interest, as both light irradiance and light quality change rapidly throughout the day, causing profound changes in stem elongation and leaf area growth. Among the several dicot species examined, we have focused on sunflower (Helianthus annuus L.) because its shoots are robust and their growth is highly plastic. Sunflower shoots thus constitute an ideal tissue for assessing responses to both light irradiance and light quality signals. Herein, we discuss the possible roles of gibberellins, auxin, ethylene, cytokinins and brassinosteroids in mediating the stem elongation and leaf area growth that is induced by shade light. To do this we uncoupled the plant's responses to changes in the red to far-red [R/FR] light ratio from its responses to changes in irradiance of photosynthetically active radiation [PAR]. Reducing each of R/FR light ratio and PAR irradiance results in increased sunflower stem elongation. However, the plant's response for leaf area growth differs considerably, with a low R/FR ratio generally promoting leaf area growth, whereas low irradiance PAR inhibits it. The increased stem elongation that occurs in response to lowering R/FR ratio and PAR irradiance is accomplished at the expense of leaf area growth. In effect, the low PAR irradiance signal overrides the low R/FR ratio signal in shade light's control of leaf growth and development. Three hormone groups, gibberellins, auxin and ethylene are directly involved in regulating these light-mediated shoot growth changes. Gibberellins and auxin function as growth promoters, with auxin likely acting as an up-regulator of gibberellin biosynthesis. Ethylene functions as a growth-inhibitor and probably interacts with gibberellins in regulating both stem and leaf growth of the sunflower shoot. PMID:25443853

  1. Complex inhibitory microcircuitry regulates retinal signaling near visual threshold.

    PubMed

    Grimes, William N; Zhang, Jun; Tian, Hua; Graydon, Cole W; Hoon, Mrinalini; Rieke, Fred; Diamond, Jeffrey S

    2015-07-01

    Neuronal microcircuits, small, localized signaling motifs involving two or more neurons, underlie signal processing and computation in the brain. Compartmentalized signaling within a neuron may enable it to participate in multiple, independent microcircuits. Each A17 amacrine cell in the mammalian retina contains within its dendrites hundreds of synaptic feedback microcircuits that operate independently to modulate feedforward signaling in the inner retina. Each of these microcircuits comprises a small (<1 μm) synaptic varicosity that typically receives one excitatory synapse from a presynaptic rod bipolar cell (RBC) and returns two reciprocal inhibitory synapses back onto the same RBC terminal. Feedback inhibition from the A17 sculpts the feedforward signal from the RBC to the AII, a critical component of the circuitry mediating night vision. Here, we show that the two inhibitory synapses from the A17 to the RBC express kinetically distinct populations of GABA receptors: rapidly activating GABA(A)Rs are enriched at one synapse while more slowly activating GABA(C)Rs are enriched at the other. Anatomical and electrophysiological data suggest that macromolecular complexes of voltage-gated (Cav) channels and Ca(2+)-activated K(+) channels help to regulate GABA release from A17 varicosities and limit GABA(C)R activation under certain conditions. Finally, we find that selective elimination of A17-mediated feedback inhibition reduces the signal to noise ratio of responses to dim flashes recorded in the feedforward pathway (i.e., the AII amacrine cell). We conclude that A17-mediated feedback inhibition improves the signal to noise ratio of RBC-AII transmission near visual threshold, thereby improving visual sensitivity at night. PMID:25972578

  2. 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

  3. Notch signaling indirectly promotes chondrocyte hypertrophy via regulation of BMP signaling and cell cycle arrest

    PubMed Central

    Shang, Xifu; Wang, Jinwu; Luo, Zhengliang; Wang, Yongjun; Morandi, Massimo M.; Marymont, John V.; Hilton, Matthew J.; Dong, Yufeng

    2016-01-01

    Cell cycle regulation is critical for chondrocyte differentiation and hypertrophy. Recently we identified the Notch signaling pathway as an important regulator of chondrocyte proliferation and differentiation during mouse cartilage development. To investigate the underlying mechanisms, we assessed the role for Notch signaling regulation of the cell cycle during chondrocyte differentiation. Real-time RT-PCR data showed that over-expression of the Notch Intracellular Domain (NICD) significantly induced the expression of p57, a cell cycle inhibitor, in chondrocytes. Flow cytometric analyses further confirmed that over-expression of NICD in chondrocytes enhances the G0/G1 cell cycle transition and cell cycle arrest. In contrast, treatment of chondrocytes with the Notch inhibitor, DAPT, decreased both endogenous and BMP2-induced SMAD 1/5/8 phosphorylation and knockdown of SMAD 1/5/8 impaired NICD-induced chondrocyte differentiation and p57 expression. Co-immunoprecipitation using p-SMAD 1/5/8 and NICD antibodies further showed a strong interaction of these proteins during chondrocyte maturation. Finally, RT-PCR and Western blot results revealed a significant reduction in the expression of the SMAD-related phosphatase, PPM1A, following NICD over-expression. Taken together, our results demonstrate that Notch signaling induces cell cycle arrest and thereby initiates chondrocyte hypertrophy via BMP/SMAD-mediated up-regulation of p57. PMID:27146698

  4. Signaling by bone morphogenetic proteins directs formation of an ectodermal signaling center that regulates craniofacial development.

    PubMed

    Foppiano, Silvia; Hu, Diane; Marcucio, Ralph S

    2007-12-01

    We previously described a signaling center, the Frontonasal Ectodermal Zone (FEZ) that regulates growth and patterning of the frontonasal process (FNP). The FEZ is comprised of FNP ectoderm flanking a boundary between Sonic hedgehog (Shh) and Fibroblast growth factor 8 (Fgf8) expression domains. Our objective was to examine BMP signaling during formation of the FEZ. We blocked BMP signaling throughout the FNP prior to FEZ formation by infecting chick embryos at stage 10 (HH10) with a replication-competent avian retrovirus encoding the BMP antagonist Noggin. We assessed gene expression patterns in the FNP 72 h after infection (approximately HH22) and observed that Shh expression was reduced or absent. In the mesenchyme, we observed that Bmp2 transcripts were absent while the Bmp4 expression domain was expanded proximally. In addition to the molecular changes, infected embryos also exhibited facial malformations at 72 and 96 h after infection suggesting that the FEZ did not form. Our data indicate that reduced cell proliferation, but not apoptosis, in the mesenchyme contributed to the phenotype that we observed. Additionally, adding exogenous SHH into the mesenchyme of RCAS-Noggin-infected embryos did not restore Bmp2 and Bmp4 to a normal pattern of expression. These data indicate that BMP signaling mediates interactions between tissues in the FNP that regulate FEZ formation; and that the correct pattern of Bmp2 and Bmp4, but not Bmp7, expression in the FNP mesenchyme requires signaling by the BMP pathway.

  5. Mapping paths: new approaches to dissect eukaryotic signaling circuitry.

    PubMed

    Mutlu, Nebibe; Kumar, Anuj

    2016-01-01

    Eukaryotic cells are precisely "wired" to coordinate changes in external and intracellular signals with corresponding adjustments in the output of complex and often interconnected signaling pathways. These pathways are critical in understanding cellular growth and function, and several experimental trends are emerging with applicability toward more fully describing the composition and topology of eukaryotic signaling networks. In particular, recent studies have implemented CRISPR/Cas-based screens in mouse and human cell lines for genes involved in various cell growth and disease phenotypes. Proteomic methods using mass spectrometry have enabled quantitative and dynamic profiling of protein interactions, revealing previously undiscovered complexes and allele-specific protein interactions. Methods for the single-cell study of protein localization and gene expression have been integrated with computational analyses to provide insight into cell signaling in yeast and metazoans. In this review, we present an overview of exemplary studies using the above approaches, relevant for the analysis of cell signaling and indeed, more broadly, for many modern biological applications.

  6. Mapping paths: new approaches to dissect eukaryotic signaling circuitry

    PubMed Central

    Mutlu, Nebibe; Kumar, Anuj

    2016-01-01

    Eukaryotic cells are precisely “wired” to coordinate changes in external and intracellular signals with corresponding adjustments in the output of complex and often interconnected signaling pathways. These pathways are critical in understanding cellular growth and function, and several experimental trends are emerging with applicability toward more fully describing the composition and topology of eukaryotic signaling networks. In particular, recent studies have implemented CRISPR/Cas-based screens in mouse and human cell lines for genes involved in various cell growth and disease phenotypes. Proteomic methods using mass spectrometry have enabled quantitative and dynamic profiling of protein interactions, revealing previously undiscovered complexes and allele-specific protein interactions. Methods for the single-cell study of protein localization and gene expression have been integrated with computational analyses to provide insight into cell signaling in yeast and metazoans. In this review, we present an overview of exemplary studies using the above approaches, relevant for the analysis of cell signaling and indeed, more broadly, for many modern biological applications. PMID:27540473

  7. Negative Regulation of Cytoplasmic RNA-Mediated Antiviral Signaling

    PubMed Central

    Komuro, Akihiko; Bamming, Darja

    2008-01-01

    The recent, rapid progress in our understanding of cytoplasmic RNA-mediated antiviral innate immune signaling was initiated by the discovery of retinoic acid-inducible gene I (RIG-I) as a sensor of viral RNA [1]. It is now widely recognized that RIG-I and related RNA helicases, melanoma differentiated-associated gene-5 (MDA5) and laboratory of genetics and physiology-2 (LGP2), can initiate and/or regulate RNA and virus -mediated type I IFN production and antiviral responses. As with other cytokine systems, production of type I IFN is a transient process, and can be hazardous to the host if unregulated, resulting in chronic cellular toxicity or inflammatory and autoimmune diseases [2-9]. In addition, the RIG-I-like receptor (RLR) system is a fundamental target for virus-encoded immune suppression, with many indirect and direct examples of interference described. In this article, we review the current understanding of endogenous negative regulation in RLR signaling and explore direct inhibition of RLR signaling by viruses as a host immune evasion strategy. PMID:18703349

  8. Noncoding RNAs Regulating p53 and c-Myc Signaling.

    PubMed

    Mei, Yide; Wu, Mian

    2016-01-01

    p53 is one of the most important tumor suppressors and is known to play critical roles in the process of tumor development. Similarly, as an important proto-oncogenes, c-Myc is activated in over half of human cancers. Both p53 and c-Myc participate in almost every crucial decision of almost every cell. Therefore, it is utmost important to gain a better understanding of how they affect multiple cellular processes. The physiological and pathologic patterns of p53 and c-Myc regulations are modulated by a large number of cis-elements and transfactors (RNAs and proteins). These elements and factors are composed of a complicated network of intracellular and extracellular pathways. How the noncoding RNAs are involved in their regulations has not been comprehensively reviewed. In this chapter, we will list and describe recently published important noncoding RNAs including microRNAs and long noncoding RNAs, which act as effectors and regulators for both p53 and c-Myc regulation. The purpose of this chapter is to provide a recent progress of noncoding RNA in the regulation of p53 and c-Myc on network of cellular signaling and its potential implications in both basic science and clinical application. PMID:27376742

  9. Signal inhibition by a dynamically regulated pool of monophosphorylated MAPK

    PubMed Central

    Nagiec, Michal J.; McCarter, Patrick C.; Kelley, Joshua B.; Dixit, Gauri; Elston, Timothy C.; Dohlman, Henrik G.

    2015-01-01

    Protein kinases regulate a broad array of cellular processes and do so through the phosphorylation of one or more sites within a given substrate. Many protein kinases are themselves regulated through multisite phosphorylation, and the addition or removal of phosphates can occur in a sequential (processive) or a stepwise (distributive) manner. Here we measured the relative abundance of the monophosphorylated and dual-phosphorylated forms of Fus3, a member of the mitogen-activated protein kinase (MAPK) family in yeast. We found that upon activation with pheromone, a substantial proportion of Fus3 accumulates in the monophosphorylated state. Introduction of an additional copy of Fus3 lacking either phosphorylation site leads to dampened signaling. Conversely, cells lacking the dual-specificity phosphatase (msg5Δ) or that are deficient in docking to the MAPK-scaffold (Ste5ND) accumulate a greater proportion of dual-phosphorylated Fus3. The double mutant exhibits a synergistic, or “synthetic,” supersensitivity to pheromone. Finally, we present a predictive computational model that combines MAPK scaffold and phosphatase activities and is sufficient to account for the observed MAPK profiles. These results indicate that the monophosphorylated and dual-phosphorylated forms of the MAPK act in opposition to one another. Moreover, they reveal a new mechanism by which the MAPK scaffold acts dynamically to regulate signaling. PMID:26179917

  10. Retrograde neurotrophin signaling through Tollo regulates synaptic growth in Drosophila

    PubMed Central

    Miller, Daniel L.; Ganetzky, Barry

    2014-01-01

    Toll-like receptors (TLRs) are best characterized for their roles in mediating dorsoventral patterning and the innate immune response. However, recent studies indicate that TLRs are also involved in regulating neuronal growth and development. Here, we demonstrate that the TLR Tollo positively regulates growth of the Drosophila melanogaster larval neuromuscular junction (NMJ). Tollo mutants exhibited NMJ undergrowth, whereas increased expression of Tollo led to NMJ overgrowth. Tollo expression in the motoneuron was both necessary and sufficient for regulating NMJ growth. Dominant genetic interactions together with altered levels of phosphorylated c-Jun N-terminal kinase (JNK) and puc-lacZ expression revealed that Tollo signals through the JNK pathway at the NMJ. Genetic interactions also revealed that the neurotrophin Spätzle3 (Spz3) is a likely Tollo ligand. Spz3 expression in muscle and proteolytic activation via the Easter protease was necessary and sufficient to promote NMJ growth. These results demonstrate the existence of a novel neurotrophin signaling pathway that is required for synaptic development in Drosophila. PMID:24662564

  11. Tubedown regulation of retinal endothelial permeability signaling pathways

    PubMed Central

    Ho, Nhu; Gendron, Robert L.; Grozinger, Kindra; Whelan, Maria A.; Hicks, Emily Anne; Tennakoon, Bimal; Gardiner, Danielle; Good, William V.; Paradis, Hélène

    2015-01-01

    ABSTRACT Tubedown (Tbdn; Naa15), a subunit of the N-terminal acetyltransferase NatA, complexes with the c-Src substrate Cortactin and supports adult retinal homeostasis through regulation of vascular permeability. Here we investigate the role of Tbdn expression on signaling components of retinal endothelial permeability to understand how Tbdn regulates the vasculature and supports retinal homeostasis. Tbdn knockdown-induced hyperpermeability to Albumin in retinal endothelial cells was associated with an increase in the levels of activation of the Src family kinases (SFK) c-Src, Fyn and Lyn and phospho-Cortactin (Tyr421). The knockdown of Cortactin expression reduced Tbdn knockdown-induced permeability to Albumin and the levels of activated SFK. Inhibition of SFK in retinal endothelial cells decreased Tbdn knockdown-induced permeability to Albumin and phospho-Cortactin (Tyr421) levels. Retinal lesions of endothelial-specific Tbdn knockdown mice, with tissue thickening, fibrovascular growth, and hyperpermeable vessels displayed an increase in the levels of activated c-Src. Moreover, the retinal lesions of patients with proliferative diabetic retinopathy (PDR) associated with a loss of Tbdn expression and hyperpermeability to Albumin displayed increased levels of activated SFK in retinal blood vessels. Taken together, these results implicate Tbdn as an important regulator of retinal endothelial permeability and homeostasis by modulating a signaling pathway involving c-Src and Cortactin. PMID:26142315

  12. Regulation of T-cell receptor signalling by membrane microdomains

    PubMed Central

    Razzaq, Tahir M; Ozegbe, Patricia; Jury, Elizabeth C; Sembi, Phupinder; Blackwell, Nathan M; Kabouridis, Panagiotis S

    2004-01-01

    There is now considerable evidence suggesting that the plasma membrane of mammalian cells is compartmentalized by functional lipid raft microdomains. These structures are assemblies of specialized lipids and proteins and have been implicated in diverse biological functions. Analysis of their protein content using proteomics and other methods revealed enrichment of signalling proteins, suggesting a role for these domains in intracellular signalling. In T lymphocytes, structure/function experiments and complementary pharmacological studies have shown that raft microdomains control the localization and function of proteins which are components of signalling pathways regulated by the T-cell antigen receptor (TCR). Based on these studies, a model for TCR phosphorylation in lipid rafts is presented. However, despite substantial progress in the field, critical questions remain. For example, it is unclear if membrane rafts represent a homogeneous population and if their structure is modified upon TCR stimulation. In the future, proteomics and the parallel development of complementary analytical methods will undoubtedly contribute in further delineating the role of lipid rafts in signal transduction mechanisms. PMID:15554919

  13. A topographic instructive signal guides the adjustment of the auditory space map in the optic tectum.

    PubMed

    Hyde, P S; Knudsen, E I

    2001-11-01

    Maps of auditory space in the midbrain of the barn owl (Tyto alba) are calibrated by visual experience. When owls are raised wearing prismatic spectacles that displace the visual field in azimuth, the auditory receptive fields of neurons in the optic tectum shift to compensate for the optical displacement of the visual field. This shift results primarily from a shift in the tuning of tectal neurons for interaural time difference. The visually based instructive signal that guides this plasticity could be based on a topographic, point-by-point comparison between auditory and visual space maps or on a foveation-dependent visual assessment of the accuracy of auditory orienting responses. To distinguish between these two possibilities, we subjected owls to optical conditions that differed in the center of gaze and the visual periphery. A topographic signal would cause the portions of the space map representing the central and peripheral regions of visual space to adjust differently, according to the optical conditions that exist in each region. In contrast, a foveation-based signal would cause both portions of the map to adjust similarly, according to the optical conditions that exist at the center of gaze. In six of seven experiments, adaptive changes were as predicted by a topographic instructive signal. Although the results do not rule out the possible contribution of a foveation-based signal, they demonstrate that a topographic instructive signal is, indeed, involved in the calibration of the auditory space map in the barn owl optic tectum. PMID:11606646

  14. Ex Vivo Signaling Protein Mapping in T Lymphocytes in the Psoriatic Arthritis Joints.

    PubMed

    Fiocco, Ugo; Martini, Veronica; Accordi, Benedetta; Caso, Francesco; Costa, Luisa; Oliviero, Francesca; Scanu, Anna; Felicetti, Mara; Frallonardo, Paola; Facco, Monica; Boso, Daniele; Molena, Beatrice; Zambello, Renato; Ramonda, Roberta; Cozzi, Franco; Scarpa, Raffaele; Basso, Giuseppe; Semenzato, Gianpietro; Dayer, Jean-Michel; Doria, Andrea; Punzi, Leonardo

    2015-11-01

    We assessed signaling protein mapping in total T cells, to analyze the proportions of T regulatory (Treg) and TCD4+ effector (Teff) cell phenotypes, and the respective interleukin 6Rα (IL-6Rα) expression in the inflammatory microenvironment of synovial fluid (SF) of patients with sustained psoriatic arthritis (PsA). Our approach was to measure the IL-6 level in SF using a multiplex bead immunoassay. Reverse-phase protein array was used to assess Janus kinase (JAK) 1 and JAK2, extra-cellular regulated kinase (ERK) 1 and 2, protein kinase Cδ (PKCδ), signal transducer and activator and transcription (STAT) 1, STAT3, and STAT5 phosphoproteins in total T cell lysates from SF of patients with PsA. Frequencies of CD4+IL-17A-F+IL-23+ CD4+ Th cells producing IL-17A and IL-17F (Th17) and CD4+CD25high intracellular forkhead box transcription factor+ (FOXP3+) phenotypes, and the percentage of Treg- and Teff- cells were quantified in SF and matched peripheral blood (PB) of patients with PsA and PB of healthy controls (HC) by flow cytometry. Our results were the following: In PsA SF samples, a coordinate increase of JAK1, ERK1/2, STAT1, STAT3, and STAT5 phosphoproteins was found in total T cells in SF of PsA; where IL-6 levels were higher than in PB from HC. Expanded CD4+IL-17A-F+IL-23+ Th17, CD4+ CD25- Teff- and CD4+CD25(high) FoxP3+Treg subsets, showing similar levels of enhanced IL-6Rδ expression, were confined to PsA joints. In our studies, the transcriptional network profile identified by ex vivo signaling protein mapping in T lymphocytes in PsA joints revealed the complex interplay between IL-1, IL-6, and IL-23 signaling and differentiation of Th17 cells and CD4+Tregs in sustained joint inflammation in PsA. PMID:26523057

  15. CGI-58, a key regulator of lipid homeostasis and signaling in plants, also regulates polyamine metabolism

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Comparative Gene Identification-58 (CGI-58) is an alpha/beta hydrolase-type protein that regulates lipid homeostasis and signaling in eukaryotes by interacting with and stimulating the activity of several different types of proteins, including a lipase in mammalian cells and a peroxisomal ABC transp...

  16. Emerging EPO and EPO receptor regulators and signal transducers

    PubMed Central

    Kuhrt, David

    2015-01-01

    As essential mediators of red cell production, erythropoietin (EPO) and its cell surface receptor (EPO receptor [EPOR]) have been intensely studied. Early investigations defined basic mechanisms for hypoxia-inducible factor induction of EPO expression, and within erythroid progenitors EPOR engagement of canonical Janus kinase 2/signal transducer and activator of transcription 5 (JAK2/STAT5), rat sarcoma/mitogen-activated protein kinase/extracellular signal-regulated kinase (RAS/MEK/ERK), and phosphatidylinositol 3-kinase (PI3K) pathways. Contemporary genetic, bioinformatic, and proteomic approaches continue to uncover new clinically relevant modulators of EPO and EPOR expression, and EPO’s biological effects. This Spotlight review highlights such factors and their emerging roles during erythropoiesis and anemia. PMID:25887776

  17. Pneumococcal hydrogen peroxide-induced stress signaling regulates inflammatory genes.

    PubMed

    Loose, Maria; Hudel, Martina; Zimmer, Klaus-Peter; Garcia, Ernesto; Hammerschmidt, Sven; Lucas, Rudolf; Chakraborty, Trinad; Pillich, Helena

    2015-01-15

    Microbial infections can induce aberrant responses in cellular stress pathways, leading to translational attenuation, metabolic restriction, and activation of oxidative stress, with detrimental effects on cell survival. Here we show that infection of human airway epithelial cells with Streptococcus pneumoniae leads to induction of endoplasmic reticulum (ER) and oxidative stress, activation of mitogen-associated protein kinase (MAPK) signaling pathways, and regulation of their respective target genes. We identify pneumococcal H2O2 as the causative agent for these responses, as both catalase-treated and pyruvate oxidase-deficient bacteria lacked these activities. Pneumococcal H2O2 induced nuclear NF-κB translocation and transcription of proinflammatory cytokines. Inhibition of translational arrest and ER stress by salubrinal or of MAPK signaling pathways attenuate cytokine transcription. These results provide strong evidence for the notion that inhibition of translation is an important host pathway in monitoring harmful pathogen-associated activities, thereby enabling differentiation between pathogenic and nonpathogenic bacteria. PMID:25183769

  18. Emerging EPO and EPO receptor regulators and signal transducers.

    PubMed

    Kuhrt, David; Wojchowski, Don M

    2015-06-01

    As essential mediators of red cell production, erythropoietin (EPO) and its cell surface receptor (EPO receptor [EPOR]) have been intensely studied. Early investigations defined basic mechanisms for hypoxia-inducible factor induction of EPO expression, and within erythroid progenitors EPOR engagement of canonical Janus kinase 2/signal transducer and activator of transcription 5 (JAK2/STAT5), rat sarcoma/mitogen-activated protein kinase/extracellular signal-regulated kinase (RAS/MEK/ERK), and phosphatidylinositol 3-kinase (PI3K) pathways. Contemporary genetic, bioinformatic, and proteomic approaches continue to uncover new clinically relevant modulators of EPO and EPOR expression, and EPO's biological effects. This Spotlight review highlights such factors and their emerging roles during erythropoiesis and anemia. PMID:25887776

  19. A cotton Raf-like MAP3K gene, GhMAP3K40, mediates reduced tolerance to biotic and abiotic stress in Nicotiana benthamiana by negatively regulating growth and development.

    PubMed

    Chen, Xiaobo; Wang, Ji; Zhu, Ming; Jia, Haihong; Liu, Dongdong; Hao, Lili; Guo, Xingqi

    2015-11-01

    Mitogen-activated protein kinase (MAPK) cascades mediate various responses in plants. As the top component, MAP3Ks deserve more attention; however, little is known about the role of MAP3Ks, especially in cotton, a worldwide economic crop. In this study, a gene encoding a putative Raf-like MAP3K, GhMAP3K40, was isolated. GhMAP3K40 expression was induced by stress and multiple signal molecules. The plants overexpressing GhMAP3K40 had an enhanced tolerance to drought and salt stress at the germination stage. However, at the seedling stage, the transgenic plants suffered more severe damage after drought, exposure to pathogens and oxidative stress. The defence-related genes and the antioxidant system were activated in transgenic palnts, suggesting that GhMAP3K40 positively regulate the defence response. The transgenic plants were less able to prevent pathogenic invasion, which was due to defects in the cell structure of the leaves. The root system of the control plants were stronger compared with the transgenic plants. These results indicated a negative role of GhMAP3K40 in growth and development and GhMAP3K40 possibly caused the defects by down-regulating the lignin biosynthesis. Overall, these results suggest that GhMAP3K40 may positively regulate defence response but cause reduced tolerance to biotic and abiotic stress by negatively regulating growth and development. PMID:26475184

  20. A cotton Raf-like MAP3K gene, GhMAP3K40, mediates reduced tolerance to biotic and abiotic stress in Nicotiana benthamiana by negatively regulating growth and development.

    PubMed

    Chen, Xiaobo; Wang, Ji; Zhu, Ming; Jia, Haihong; Liu, Dongdong; Hao, Lili; Guo, Xingqi

    2015-11-01

    Mitogen-activated protein kinase (MAPK) cascades mediate various responses in plants. As the top component, MAP3Ks deserve more attention; however, little is known about the role of MAP3Ks, especially in cotton, a worldwide economic crop. In this study, a gene encoding a putative Raf-like MAP3K, GhMAP3K40, was isolated. GhMAP3K40 expression was induced by stress and multiple signal molecules. The plants overexpressing GhMAP3K40 had an enhanced tolerance to drought and salt stress at the germination stage. However, at the seedling stage, the transgenic plants suffered more severe damage after drought, exposure to pathogens and oxidative stress. The defence-related genes and the antioxidant system were activated in transgenic palnts, suggesting that GhMAP3K40 positively regulate the defence response. The transgenic plants were less able to prevent pathogenic invasion, which was due to defects in the cell structure of the leaves. The root system of the control plants were stronger compared with the transgenic plants. These results indicated a negative role of GhMAP3K40 in growth and development and GhMAP3K40 possibly caused the defects by down-regulating the lignin biosynthesis. Overall, these results suggest that GhMAP3K40 may positively regulate defence response but cause reduced tolerance to biotic and abiotic stress by negatively regulating growth and development.

  1. Host mTORC1 Signaling Regulates Andes Virus Replication

    PubMed Central

    McNulty, Shannon; Flint, Mike; Nichol, Stuart T.

    2013-01-01

    Hantavirus pulmonary syndrome (HPS) is a severe respiratory disease characterized by pulmonary edema, with fatality rates of 35 to 45%. Disease occurs following infection with pathogenic New World hantaviruses, such as Andes virus (ANDV), which targets lung microvascular endothelial cells. During replication, the virus scavenges 5′-m7G caps from cellular mRNA to ensure efficient translation of viral proteins by the host cell cap-dependent translation machinery. In cells, the mammalian target of rapamycin (mTOR) regulates the activity of host cap-dependent translation by integrating amino acid, energy, and oxygen availability signals. Since there is no approved pharmacological treatment for HPS, we investigated whether inhibitors of the mTOR pathway could reduce hantavirus infection. Here, we demonstrate that treatment with the FDA-approved rapamycin analogue temsirolimus (CCI-779) blocks ANDV protein expression and virion release but not entry into primary human microvascular endothelial cells. This effect was specific to viral proteins, as temsirolimus treatment did not block host protein synthesis. We confirmed that temsirolimus targeted host mTOR complex 1 (mTORC1) and not a viral protein, as knockdown of mTORC1 and mTORC1 activators but not mTOR complex 2 components reduced ANDV replication. Additionally, primary fibroblasts from a patient with tuberous sclerosis exhibited increased mTORC1 activity and increased ANDV protein expression, which were blocked following temsirolimus treatment. Finally, we show that ANDV glycoprotein Gn colocalized with mTOR and lysosomes in infected cells. Together, these data demonstrate that mTORC1 signaling regulates ANDV replication and suggest that the hantavirus Gn protein may modulate mTOR and lysosomal signaling during infection, thus bypassing the cellular regulation of translation. PMID:23135723

  2. Identification of a neurovascular signaling pathway regulating seizures in mice

    PubMed Central

    Fredriksson, Linda; Stevenson, Tamara K; Su, Enming J; Ragsdale, Margaret; Moore, Shannon; Craciun, Stefan; Schielke, Gerald P; Murphy, Geoffrey G; Lawrence, Daniel A

    2015-01-01

    Objective A growing body of evidence suggests that increased blood–brain barrier (BBB) permeability can contribute to the development of seizures. The protease tissue plasminogen activator (tPA) has been shown to promote BBB permeability and susceptibility to seizures. In this study, we examined the pathway regulated by tPA in seizures. Methods An experimental model of kainate-induced seizures was used in genetically modified mice, including mice deficient in tPA (tPA−/−), its inhibitor neuroserpin (Nsp−/−), or both (Nsp:tPA−/−), and in mice conditionally deficient in the platelet-derived growth factor receptor alpha (PDGFRα). Results Compared to wild-type (WT) mice, Nsp−/− mice have significantly reduced latency to seizure onset and generalization; whereas tPA−/− mice have the opposite phenotype, as do Nsp:tPA−/− mice. Furthermore, interventions that maintain BBB integrity delay seizure propagation, whereas osmotic disruption of the BBB in seizure-resistant tPA−/− mice dramatically reduces the time to seizure onset and accelerates seizure progression. The phenotypic differences in seizure progression between WT, tPA−/−, and Nsp−/− mice are also observed in electroencephalogram recordings in vivo, but absent in ex vivo electrophysiological recordings where regulation of the BBB is no longer necessary to maintain the extracellular environment. Finally, we demonstrate that these effects on seizure progression are mediated through signaling by PDGFRα on perivascular astrocytes. Interpretation Together, these data identify a specific molecular pathway involving tPA-mediated PDGFRα signaling in perivascular astrocytes that regulates seizure progression through control of the BBB. Inhibition of PDGFRα signaling and maintenance of BBB integrity might therefore offer a novel clinical approach for managing seizures. PMID:26273685

  3. AlzPathway, an Updated Map of Curated Signaling Pathways: Towards Deciphering Alzheimer's Disease Pathogenesis.

    PubMed

    Ogishima, Soichi; Mizuno, Satoshi; Kikuchi, Masataka; Miyashita, Akinori; Kuwano, Ryozo; Tanaka, Hiroshi; Nakaya, Jun

    2016-01-01

    Alzheimer's disease (AD) is a complex neurodegenerative disorder in which loss of neurons and synaptic function causes dementia in the elderly. To clarify AD pathogenesis and develop drugs for AD, thousands of studies have elucidated signaling pathways involved. However, knowledge of AD signaling pathways has not been compiled as a pathway map. In this chapter, we introduce the manual construction of a pathway map in AD which we call "AlzPathway", that comprehensively catalogs signaling pathways in the field of AD. We have collected and manually curated over 100 review articles related to AD, and have built the AD pathway map. AlzPathway is currently composed of thousands of molecules and reactions in neurons, brain blood barrier, presynaptic, postsynaptic, astrocyte, and microglial cells, with their cellular localizations. AlzPathway provides a systems-biology platform of comprehensive AD signaling and related pathways which is expected to contribute to clarification of AD pathogenesis and AD drug development.

  4. Mapping toll-like receptor signaling pathway genes of Zhikong scallop ( Chlamys farreri) with FISH

    NASA Astrophysics Data System (ADS)

    Zhao, Bosong; Zhao, Liang; Liao, Huan; Cheng, Jie; Lian, Shanshan; Li, Xuan; Huang, Xiaoting; Bao, Zhenmin

    2015-12-01

    Toll-like receptor (TLR) signaling pathway plays a pivotal role in the innate immune system. Studies on TLR signaling pathway genes in Zhikong scallop ( Chlamys farreri) have mainly focused on sequence analysis and expression profiling, no research has been carried out on their localization. The chromosomal position of TLR signaling pathway genes can be valuable for assemblying scallop genome and analysizing gene regulatory networks. In the present study, five key TLR signaling pathway genes ( CfTLR, CfMyd88, CfTRAF6, CfNFκB, and CfIκB) containing bacterial artificial chromosomes (BACs) were isolated and physically mapped through fluorescence in situ hybridization on five non-homologous chromosome pairs, showing a similar distribution to another five model species. The isolation and mapping of these key immune genes of C. farreri will aid to the research on innate immunity, assignment of interested genes to chromosomes, and integration of physical, linkage and cytogenetic maps of this species.

  5. Regulation of connexin signaling by the epigenetic machinery

    PubMed Central

    Vinken, Mathieu

    2015-01-01

    Connexins and their channels are involved in the control of all aspects of the cellular life cycle, ranging from cell growth to cell death, by mediating extracellular, intercellular and intracellular communication. These multifaceted aspects of connexin-related cellular signaling obviously require strict regulation. While connexin channel activity is mainly directed by posttranslational modifications, connexin expression as such is managed by classical cis/trans mechanisms. Over the past few years, it has become clear that connexin production is equally dictated by epigenetic actions. This paper provides an overview of the role of major determinants of the epigenome, including DNA methylation, histone acetylation and microRNA species, in connexin expression. PMID:26566120

  6. Regulation of connexin signaling by the epigenetic machinery.

    PubMed

    Vinken, Mathieu

    2016-02-01

    Connexins and their channels are involved in the control of all aspects of the cellular life cycle, ranging from cell growth to cell death, by mediating extracellular, intercellular and intracellular communication. These multifaceted aspects of connexin-related cellular signaling obviously require strict regulation. While connexin channel activity is mainly directed by posttranslational modifications, connexin expression as such is managed by classical cis/trans mechanisms. Over the past few years, it has become clear that connexin production is equally dictated by epigenetic actions. This paper provides an overview of the role of major determinants of the epigenome, including DNA methylation, histone acetylation and microRNA species, in connexin expression. PMID:26566120

  7. Small-signal, continuous, exact model of PWM voltage regulators

    NASA Astrophysics Data System (ADS)

    Burkhardt, W.; Maranesi, P.; Varoli, V.

    1985-02-01

    The small-signal time-continuous open-loop response of buck, boost, and buck-boost pulse-width-modulation (PWM) voltage regulators using MOSFET switches in their power stages is modeled, applying a time-domain sampling theorem (Woodward, 1953) to obtain the Fourier open-loop transfer function corresponding to the comb function describing the response at the chopping instants only. The results are presented graphically along with simplified circuit diagrams of the PWM devices, and the accuracy and computational efficiency of the analytical approach are indicated.

  8. Fisetin regulates obesity by targeting mTORC1 signaling.

    PubMed

    Jung, Chang Hwa; Kim, Heemun; Ahn, Jiyun; Jeon, Tae-Il; Lee, Dae-Hee; Ha, Tae-Youl

    2013-08-01

    Fisetin, a flavonol present in vegetables and fruits, possesses antioxidative and anti-inflammatory properties. In this study, we have demonstrated that fisetin prevents diet-induced obesity through regulation of the signaling of mammalian target of rapamycin complex 1 (mTORC1), a central mediator of cellular growth, cellular proliferation and lipid biosynthesis. To evaluate whether fisetin regulates mTORC1 signaling, we investigated the phosphorylation and kinase activity of the 70-kDa ribosomal protein S6 kinase 1 (S6K1) and mTORC1 in 3T3-L1 preadipocytes. Fisetin treatment of preadipocytes reduced the phosphorylation of S6K1 and mTORC1 in a time- and concentration-dependent manner. To further our understanding of how fisetin negatively regulates mTORC1 signaling, we analyzed the phosphorylation of S6K1, mTOR and Akt in fisetin-treated TSC2-knockdown cells. The results suggested that fisetin treatment inhibits mTORC1 activity in an Akt-dependent manner. Recent studies have shown that adipocyte differentiation is dependent on mTORC1 activity. Fisetin treatment inhibited adipocyte differentiation, consistent with the negative effect of fisetin on mTOR. The inhibitory effect of fisetin on adipogenesis is dependent of mTOR activity, suggesting that fisetin inhibits adipogenesis and the accumulation of intracellular triglycerides during adipocyte differentiation by targeting mTORC1 signaling. Fisetin supplementation in mice fed a high-fat diet (HFD) significantly attenuated HFD-induced increases in body weight and white adipose tissue. We also observed that fisetin efficiently suppressed the phosphorylation of Akt, S6K1 and mTORC1 in adipose tissue. Collectively, these results suggest that inhibition of mTORC1 signaling by fisetin prevents adipocyte differentiation of 3T3-L1 preadipocytes and obesity in HFD-fed mice. Therefore, fisetin may be a useful phytochemical agent for attenuating diet-induced obesity.

  9. DELLA-mediated gibberellin signalling regulates Nod factor signalling and rhizobial infection

    PubMed Central

    Fonouni-Farde, Camille; Tan, Sovanna; Baudin, Maël; Brault, Mathias; Wen, Jiangqi; Mysore, Kirankumar S.; Niebel, Andreas; Frugier, Florian; Diet, Anouck

    2016-01-01

    Legumes develop symbiotic interactions with rhizobial bacteria to form nitrogen-fixing nodules. Bacterial Nod factors (NFs) and plant regulatory pathways modulating NF signalling control rhizobial infections and nodulation efficiency. Here we show that gibberellin (GA) signalling mediated by DELLA proteins inhibits rhizobial infections and controls the NF induction of the infection marker ENOD11 in Medicago truncatula. Ectopic expression of a constitutively active DELLA protein in the epidermis is sufficient to promote ENOD11 expression in the absence of symbiotic signals. We show using heterologous systems that DELLA proteins can interact with the nodulation signalling pathway 2 (NSP2) and nuclear factor-YA1 (NF-YA1) transcription factors that are essential for the activation of NF responses. Furthermore, MtDELLA1 can bind the ERN1 (ERF required for nodulation 1) promoter and positively transactivate its expression. Overall, we propose that GA-dependent action of DELLA proteins may directly regulate the NSP1/NSP2 and NF-YA1 activation of ERN1 transcription to regulate rhizobial infections. PMID:27586842

  10. DELLA-mediated gibberellin signalling regulates Nod factor signalling and rhizobial infection.

    PubMed

    Fonouni-Farde, Camille; Tan, Sovanna; Baudin, Maël; Brault, Mathias; Wen, Jiangqi; Mysore, Kirankumar S; Niebel, Andreas; Frugier, Florian; Diet, Anouck

    2016-01-01

    Legumes develop symbiotic interactions with rhizobial bacteria to form nitrogen-fixing nodules. Bacterial Nod factors (NFs) and plant regulatory pathways modulating NF signalling control rhizobial infections and nodulation efficiency. Here we show that gibberellin (GA) signalling mediated by DELLA proteins inhibits rhizobial infections and controls the NF induction of the infection marker ENOD11 in Medicago truncatula. Ectopic expression of a constitutively active DELLA protein in the epidermis is sufficient to promote ENOD11 expression in the absence of symbiotic signals. We show using heterologous systems that DELLA proteins can interact with the nodulation signalling pathway 2 (NSP2) and nuclear factor-YA1 (NF-YA1) transcription factors that are essential for the activation of NF responses. Furthermore, MtDELLA1 can bind the ERN1 (ERF required for nodulation 1) promoter and positively transactivate its expression. Overall, we propose that GA-dependent action of DELLA proteins may directly regulate the NSP1/NSP2 and NF-YA1 activation of ERN1 transcription to regulate rhizobial infections. PMID:27586842

  11. Mapping dynamic protein interactions in MAP kinase signaling using live-cell fluorescence fluctuation spectroscopy and imaging.

    PubMed

    Slaughter, Brian D; Schwartz, Joel W; Li, Rong

    2007-12-18

    Fluorescence correlation spectroscopy (FCS), fluorescence cross-correlation spectroscopy (FCCS), and photon counting histograms (PCH) are fluctuation methods that emerged recently as potentially useful tools for obtaining parameters of molecular dynamics, interactions, and oligomerization in vivo. Here, we report the successful implementation of FCS, FCCS, and PCH in live yeast cells using fluorescent protein-tagged proteins expressed from their native chromosomal loci, examining cytosolic dynamics and interactions among components of the mitogen activated protein kinase (MAPK) cascade, a widely occurring signaling motif, in response to mating pheromone. FCS analysis detailed the diffusion characteristics and mobile concentrations of MAPK proteins. FCCS analysis using EGFP and mCherry-tagged protein pairs observed the interactions of Ste7 (MAPK kinase) with the MAPKs, Fus3 or Kss1, and of the scaffold protein, Ste5, with Ste7 and Ste11 (MAPK kinase kinase) in the cytosol, providing in vivo constants of their binding equilibrium. The interaction of Ste5 with Fus3 in the cytosol was below the limit of detection, suggesting a weak interaction, if it exists, with K(d) >400-500 nM. Using PCH, we show that cytosolic Ste5 were mostly monomers. Artificial dimerization of Ste5, as confirmed by PCH, using a dimerizing tag, stimulated the interaction between Ste5 and Fus3. Native Ste5 was found to bind Fus3 preferentially at the cortex in pheromone-treated cells, as detected by fluorescence resonance energy transfer (FRET). These results provide a quantitative spatial map of MAPK complexes in vivo and directly support the model that membrane association and regulation of the Ste5 scaffold are critical steps in MAPK activation. PMID:18077328

  12. Human cervical cancer cells use Ca2+ signalling, protein tyrosine phosphorylation and MAP kinase in regulatory volume decrease.

    PubMed

    Shen, M R; Chou, C Y; Browning, J A; Wilkins, R J; Ellory, J C

    2001-12-01

    1. This study was aimed at identifying the signalling pathways involved in the activation of volume-regulatory mechanisms of human cervical cancer cells. 2. Osmotic swelling of human cervical cancer cells induced a substantial increase in intracellular Ca2+ ([Ca2+]i) by the activation of Ca2+ entry across the cell membrane, as well as Ca2+ release from intracellular stores. This Ca2+ signalling was critical for the normal regulatory volume decrease (RVD) response. 3. The activation of swelling-activated ion and taurine transport was significantly inhibited by tyrosine kinase inhibitors (genistein and tyrphostin AG 1478) and potentiated by the tyrosine phosphatase inhibitor Na3VO4. However, the Src family of tyrosine kinases was not involved in regulation of the swelling-activated Cl- channel. 4. Cell swelling triggered mitogen-activated protein (MAP) kinase cascades leading to the activation of extracellular signal-regulated kinase 1 and 2 (ERK1/ERK2) and p38 kinase. The volume-responsive ERK1/ERK2 signalling pathway linked with the activation of K+ and Cl- channels, and taurine transport. However, the volume-regulatory mechanism was independent of the activation of p38 MAP kinase. 5. The phosphorylated ERK1/ERK2 expression following a hypotonic shock was up-regulated by protein kinase C (PKC) activator phorbol 12-myristate 13-acetate (PMA) and down-regulated by PKC inhibitor staurosporine. The response of ERK activation to hypotonicity also required Ca2+ entry and depended on tyrosine kinase and mitogen-activated/ERK-activating kinase (MEK) activity. 6. Considering the results overall, osmotic swelling promotes the activation of tyrosine kinase and ERK1/ERK2 and raises intracellular Ca2+, all of which play a crucial role in the volume-regulatory mechanism of human cervical cancer cells. PMID:11731569

  13. Regulation of costimulatory signal in maternal-fetal immune tolerance.

    PubMed

    Jin, Li-Ping; Fan, Deng-Xuan; Li, Da-Jin

    2011-08-01

    A pregnancy is associated with modifications in the immune status of the mother, but the mechanisms are not well understood. Several observations have indicated that CD28/CTLA-4 and B7-1/B7-2 are involved in the maternal-fetal immune regulation. This review aims to recapitulate our current knowledge concerning the role of CD28/CTLA-4 and B7-1/B7-2 in maternal-fetal immune regulation. Several studies suggest that up-regulation of B7-2 and/or CD28 and/or down-regulation of CTLA-4 are correlated with the occurrence of pregnancy loss. Therefore, an accurate expression of costimulatory molecules at the maternal-fetal interface may ensure that the decidual cells do not elicit a 'danger' signal to the maternal immune system, perhaps instead contributing to the establishment of immune tolerance in vivo. It is showed that costimulation blockade with anti-B7 mAbs results in altered allogeneic T-cell response and overcomes increased maternal rejection to the fetus, which improves fetus growth in the abortion-prone system. These findings suggest that the anti-B7-treated T cells not only function as potent suppresser cells but also exert immunoregulatory effect on the maternal T cells. This procedure might be potentially useful to immunotherapy for human recurrent spontaneous abortion. PMID:21276120

  14. Extracellular Signal-Regulated Kinase Activates Topoisomerase IIα through a Mechanism Independent of Phosphorylation

    PubMed Central

    Shapiro, Paul S.; Whalen, Anne M.; Tolwinski, Nicholas S.; Wilsbacher, Julie; Froelich-Ammon, Stacie J.; Garcia, Marileila; Osheroff, Neil; Ahn, Natalie G.

    1999-01-01

    The mitogen-activated protein (MAP) kinases, extracellular signal-related kinase 1 (ERK1) and ERK2, regulate cellular responses by mediating extracellular growth signals toward cytoplasmic and nuclear targets. A potential target for ERK is topoisomerase IIα, which becomes highly phosphorylated during mitosis and is required for several aspects of nucleic acid metabolism, including chromosome condensation and daughter chromosome separation. In this study, we demonstrated interactions between ERK2 and topoisomerase IIα proteins by coimmunoprecipitation from mixtures of purified enzymes and from nuclear extracts. In vitro, diphosphorylated active ERK2 phosphorylated topoisomerase IIα and enhanced its specific activity by sevenfold, as measured by DNA relaxation assays, whereas unphosphorylated ERK2 had no effect. However, activation of topoisomerase II was also observed with diphosphorylated inactive mutant ERK2, suggesting a mechanism of activation that depends on the phosphorylation state of ERK2 but not on its kinase activity. Nevertheless, activation of ERK by transient transfection of constitutively active mutant MAP kinase kinase 1 (MKK1) enhanced endogenous topoisomerase II activity by fourfold. Our findings indicate that ERK regulates topoisomerase IIα in vitro and in vivo, suggesting a potential target for the MKK/ERK pathway in the modulation of chromatin reorganization events during mitosis and in other phases of the cell cycle. PMID:10207078

  15. Regulation of promyogenic signal transduction by cell-cell contact and adhesion

    SciTech Connect

    Krauss, Robert S.

    2010-11-01

    Skeletal myoblast differentiation involves acquisition of the muscle-specific transcriptional program and morphological changes, including fusion into multinucleated myofibers. Differentiation is regulated by extracellular signaling cues, including cell-cell contact and adhesion. Cadherin and Ig adhesion receptors have been implicated in distinct but overlapping stages of myogenesis. N-cadherin signals through the Ig receptor Cdo to activate p38 MAP kinase, while the Ig receptor neogenin signals to activate FAK; both processes promote muscle-specific gene expression and myoblast fusion. M-cadherin activates Rac1 to enhance fusion. Specific Ig receptors (Kirre and Sns) are essential for myoblast fusion in Drosophila, also signaling through Rac, and vertebrate orthologs of Kirre and Sns have partially conserved function. Mice lacking specific cytoplasmic signaling factors activated by multiple receptors (e.g., Rac1) have strong muscle phenotypes in vivo. In contrast, mice lacking individual adhesion receptors that lie upstream of these factors have modest phenotypes. Redundancy among receptors may account for this. Many of the mammalian Ig receptors and cadherins associate with each other, and multivalent interactions within these complexes may require removal of multiple components to reveal dramatic defects in vivo. Nevertheless, it is possible that the murine adhesion receptors rate-limiting in vivo have not yet been identified or fully assessed.

  16. Calcineurin/NFAT signaling in osteoblasts regulates bone mass.

    PubMed

    Winslow, Monte M; Pan, Minggui; Starbuck, Michael; Gallo, Elena M; Deng, Lei; Karsenty, Gerard; Crabtree, Gerald R

    2006-06-01

    Development and repair of the vertebrate skeleton requires the precise coordination of bone-forming osteoblasts and bone-resorbing osteoclasts. In diseases such as osteoporosis, bone resorption dominates over bone formation, suggesting a failure to harmonize osteoclast and osteoblast function. Here, we show that mice expressing a constitutively nuclear NFATc1 variant (NFATc1(nuc)) in osteoblasts develop high bone mass. NFATc1(nuc) mice have massive osteoblast overgrowth, enhanced osteoblast proliferation, and coordinated changes in the expression of Wnt signaling components. In contrast, viable NFATc1-deficient mice have defects in skull bone formation in addition to impaired osteoclast development. NFATc1(nuc) mice have increased osteoclastogenesis despite normal levels of RANKL and OPG, indicating that an additional NFAT-regulated mechanism influences osteoclastogenesis in vivo. Calcineurin/NFATc signaling in osteoblasts controls the expression of chemoattractants that attract monocytic osteoclast precursors, thereby coupling bone formation and bone resorption. Our results indicate that NFATc1 regulates bone mass by functioning in both osteoblasts and osteoclasts. PMID:16740479

  17. A locus regulating bronchial hyperresponsiveness maps to chromosome 5q

    SciTech Connect

    Levitt, R.C.; Meyers, D.A.; Bleecker, E.R.

    1994-09-01

    Bronchial hyperresponsiveness (BHR) is one of the hallmarks of asthma. BHR correlates well with asthmatic symptoms and the response to treatment. Moreover, BHR appears to be closely related to airways inflammation. Numerous studies have demonstrated a familial aggregation; however, this phenotype is not likely inherited as a simple Mendelian trait. BHR is also closely associated with total serum IgE levels, as are allergy and asthma. We studied 92 families from Northern Holland ascertained through a parent with asthma who were originally studied between 1962-1970. Since there are a number of candidate genes on chromosome 5q potentially important in producing BHR, families were genotyped for markers in this region. These genes regulate IgE production and the cellular elements that are likely involved in inflammation associated with BHR, allergy and asthma. They include IL-4, IL-3, IL-5, IL-9, IL-12, IL-13 and GM-CSF. Linkage of BHR with markers on 5q was tested using a model free sib-pair method. The data suggest a locus for BHR maps near the cytokine gene cluster on 5q. This region appears critical in producing susceptibility to BHR and possibly to asthma.

  18. Leptin differentially regulates NPY secretion in hypothalamic cell lines through distinct intracellular signal transduction pathways.

    PubMed

    Dhillon, Sandeep S; Belsham, Denise D

    2011-04-11

    Leptin acts as a key peripheral hormone in distinct neurons in the hypothalamus to modulate both reproductive function and energy homeostasis. The control of neuropeptide Y (NPY) secretion is an example of a process that can be differentially regulated by leptin. In order to further understand these distinct modulatory effects, we have used immortalized, neuronal hypothalamic cell lines expressing NPY, mHypoE-38 and mHypoE-46. We found that these cell lines express the endogenous leptin receptor, ObRb, and secrete detectable levels of NPY. We exposed the neurons to 100nM leptin for 1h and determined that the basal levels of NPY in the cell lines were differentially regulated: NPY secretion was inhibited in mHypoE-46 neurons, whereas NPY secretion was induced in the mHypoE-38 neurons. In order to determine the mechanisms involved in the divergent regulation of NPY release, we analyzed the activity of a number of signaling components using phospho-specific antibodies directed towards specific proteins in the MAP kinase, PI3K, and AMPK pathways, among others. We found that leptin activated a different combination of second messengers in each cell line. Importantly, we could link the regulation of NPY secretion to different signaling pathways, AMPK in the mHypoE-46 and both MAPK and PI3K in the mHypoE-38 neurons. This is the first demonstration that leptin can specifically regulate individual NPY neuron secretory responses through distinct signaling pathways.

  19. Regulation of EphB1 expression by dopamine signaling.

    PubMed

    Halladay, A K; Yue, Y; Michna, L; Widmer, D A; Wagner, G C; Zhou, R

    2000-12-28

    The Eph family tyrosine kinase receptors and their ligands have been implicated in axon guidance and neuronal migration during development of the nervous system. In the current study, we aim to characterize the nature of changes in EphB1 receptor expression following increases or decreases in dopamine activity. Neonatal mice (P3) were injected with 6-hydroxydopamine and allowed 13 days to recover. These animals show a profound depletion of dopamine in all areas assayed, with a corresponding dose-dependent decrease in EphB1 expression. Day 3 pups were also injected either chronically (P3-P16) or acutely (P3 only) with cocaine to determine how enhancing dopamine signaling would affect EphB1 signal density. It was found that both treatments significantly increased expression of EphB1 in the cortex, striatum and substantia nigra. Finally, animals were treated prenatally (E15-E17) with cocaine and sacrificed on P7. These animals also showed an increase in EphB1 signal density, but only in the dopaminergic terminal areas in the cortex and striatum. These studies indicate that dopamine activity regulates developmental expression of the tyrosine kinase receptor EphB1. PMID:11146119

  20. Nitrite as regulator of hypoxic signaling in mammalian physiology

    PubMed Central

    van Faassen, Ernst E.; Bahrami, Soheyl; Feelisch, Martin; Hogg, Neil; Kelm, Malte; Kim-Shapiro, Daniel B.; Kozlov, Andrey V.; Li, Haitao; Lundberg, Jon O.; Mason, Ron; Nohl, Hans; Rassaf, Tienush; Samouilov, Alexandre; Slama-Schwok, Anny; Shiva, Sruti; Vanin, Anatoly F.; Weitzberg, Eddie; Zweier, Jay; Gladwin, Mark T.

    2009-01-01

    In this review we consider the physiological effects of endogenous and pharmacological levels of nitrite under conditions of hypoxia. In humans, the nitrite anion has long been considered as metastable intermediate in the oxidation of nitric oxide radicals to the stable metabolite nitrate. This oxidation cascade was thought to be irreversible under physiological conditions. However, a growing body of experimental observations attests that the presence of endogenous nitrite regulates a number of signaling events along the physiological and pathophysiological oxygen gradient. Hypoxic signaling events include vasodilation, modulation of mitochondrial respiration, and cytoprotection following ischemic insult. These phenomena are attributed to the reduction of nitrite anions to nitric oxide if local oxygen levels in tissues decrease. Recent research identified a growing list of enzymatic and non-enzymatic pathways for this endogenous reduction of nitrite. Additional direct signaling events not involving free nitric oxide are proposed. We here discuss the mechanisms and properties of these various pathways and the role played by the local concentration of free oxygen in the affected tissue. PMID:19219851

  1. Adenosine signaling and the regulation of chronic lung disease

    PubMed Central

    Zhou, Yang; Schneider, Daniel J.; Blackburn, Michael R.

    2009-01-01

    Chronic lung diseases such as asthma, chronic obstructive pulmonary disease and interstitial lung disease are characterized by inflammation and tissue remodeling processes that compromise pulmonary function. Adenosine is produced in the inflamed and damaged lung where it plays numerous roles in the regulation of inflammation and tissue remodeling. Extracellular adenosine serves as an autocrine and paracrine signaling molecule by engaging cell surface adenosine receptors. Preclinical and cellular studies suggest that adenosine plays an anti-inflammatory role in processes associated with acute lung disease, where activation of the A2AR and A2BR have promising implications for the treatment of these disorders. In contrast, there is growing evidence that adenosine signaling through the A1R, A2BR and A3R may serve pro-inflammatory and tissue remodeling functions in chronic lung diseases. This review discusses the current progress of research efforts and clinical trials aimed at understanding the complexities of this signaling pathway as they pertain to the development of treatment strategies for chronic lung diseases. PMID:19426761

  2. Phospholipase D Controls Dictyostelium Development By Regulating G Protein Signaling

    PubMed Central

    Ray, Sibnath; Chen, Yi; Ayoung, Joanna; Hanna, Rachel; Brazill, Derrick

    2010-01-01

    Dictyostelium discoideum cells normally exist as individual amoebae, but will enter a period of multicellular development upon starvation. The initial stages of development involve the aggregation of individual cells, using cAMP as a chemoattractant. Chemotaxis is initiated when cAMP binds to its receptor, cAR1, and activates the associated G protein, Gα2βγ. However, chemotaxis will not occur unless there is a high density of starving cells present, as measured by high levels of the secreted quorum sensing molecule, CMF. We previously demonstrated that cells lacking PldB bypass the need for CMF and can aggregate at low cell density, whereas cells overexpressing pldB do not aggregate even at high cell density. Here, we found that PldB controlled both cAMP chemotaxis and cell sorting. PldB was also required by CMF to regulate G protein signaling. Specifically, CMF used PldB, to regulate the dissociation of Gα2 from Gβγ. Using fluorescence resonance energy transfer (FRET), we found that along with cAMP, CMF increased the dissociation of the G protein. In fact, CMF augmented the dissociation induced by cAMP. This augmentation was lost in cells lacking PldB. PldB appears to mediate the CMF signal through the production of phosphatidic acid, as exogenously added phosphatidic acid phenocopies overexpression of pldB. These results suggest that phospholipase D activity is required for CMF to alter the kinetics of cAMP-induced G protein signaling. PMID:20950684

  3. [RGS proteins (regulators of G protein signaling) and their roles in regulation of immune response].

    PubMed

    Lewandowicz, Anna M; Kowalski, Marek L; Pawliczak, Rafał

    2004-01-01

    RGS proteins (Regulators of G-protein Signaling) comprise a protein family responsible for regulating G proteins. By enhancing the GTPase activity of the a subunit, they speed up the reconstruction of the heterotrimeric structure of G protein, thus inhibiting its signal transduction. Sst2 protein in yeast Saccharomyces cervisiae, FlbA in fungus Aspergillus nidulans, and Egl-10 in the nematode Caenorhabditis elegans are the first native G regulators with GTPase activity (GAPs:--GTPase-activating proteins). The existence of over 30 RGS human proteins has been confirmed thus far, and they have been grouped and classified into six subfamilies. In immunocompetent cells, RGS proteins are entangled in a complicate net of different interrelating signal pathways. They are connected with B- and T-cell chemokine susceptibility, efficient T cell proliferation, and the regulation of B cell maturation. They also take an essential part in inflammation. High hopes are held for drugs, which handle would be RGS proteins and which would further provide the possibility of modifying the pharmacokinetics of drugs acting through G protein- coupled receptors. The aim of this review is to discuss the new RGS protein family and explain the potential involvement of RGS proteins in the modulation of the immune response PMID:15459549

  4. The Hippo-Salvador signaling pathway regulates renal tubulointerstitial fibrosis.

    PubMed

    Seo, Eunjeong; Kim, Wan-Young; Hur, Jeongmi; Kim, Hanbyul; Nam, Sun Ah; Choi, Arum; Kim, Yu-Mi; Park, Sang Hee; Chung, Chaeuk; Kim, Jin; Min, Soohong; Myung, Seung-Jae; Lim, Dae-Sik; Kim, Yong Kyun

    2016-08-23

    Renal tubulointerstitial fibrosis (TIF) is the final pathway of various renal injuries that result in chronic kidney disease. The mammalian Hippo-Salvador signaling pathway has been implicated in the regulation of cell proliferation, cell death, tissue regeneration, and tumorigenesis. Here, we report that the Hippo-Salvador pathway plays a role in disease development in patients with TIF and in a mouse model of TIF. Mice with tubular epithelial cell (TEC)-specific deletions of Sav1 (Salvador homolog 1) exhibited aggravated renal TIF, enhanced epithelial-mesenchymal transition-like phenotypic changes, apoptosis, and proliferation after unilateral ureteral obstruction (UUO). Moreover, Sav1 depletion in TECs increased transforming growth factor (TGF)-β and activated β-catenin expression after UUO, which likely accounts for the abovementioned enhanced TEC fibrotic phenotype. In addition, TAZ (transcriptional coactivator with PDZ-binding motif), a major downstream effector of the Hippo pathway, was significantly activated in Sav1-knockout mice in vivo. An in vitro study showed that TAZ directly regulates TGF-β and TGF-β receptor II expression. Collectively, our data indicate that the Hippo-Salvador pathway plays a role in the pathogenesis of TIF and that regulating this pathway may be a therapeutic strategy for reducing TIF.

  5. The Hippo-Salvador signaling pathway regulates renal tubulointerstitial fibrosis

    PubMed Central

    Seo, Eunjeong; Kim, Wan-Young; Hur, Jeongmi; Kim, Hanbyul; Nam, Sun Ah; Choi, Arum; Kim, Yu-Mi; Park, Sang Hee; Chung, Chaeuk; Kim, Jin; Min, Soohong; Myung, Seung-Jae; Lim, Dae-Sik; Kim, Yong Kyun

    2016-01-01

    Renal tubulointerstitial fibrosis (TIF) is the final pathway of various renal injuries that result in chronic kidney disease. The mammalian Hippo-Salvador signaling pathway has been implicated in the regulation of cell proliferation, cell death, tissue regeneration, and tumorigenesis. Here, we report that the Hippo-Salvador pathway plays a role in disease development in patients with TIF and in a mouse model of TIF. Mice with tubular epithelial cell (TEC)-specific deletions of Sav1 (Salvador homolog 1) exhibited aggravated renal TIF, enhanced epithelial-mesenchymal transition-like phenotypic changes, apoptosis, and proliferation after unilateral ureteral obstruction (UUO). Moreover, Sav1 depletion in TECs increased transforming growth factor (TGF)-β and activated β-catenin expression after UUO, which likely accounts for the abovementioned enhanced TEC fibrotic phenotype. In addition, TAZ (transcriptional coactivator with PDZ-binding motif), a major downstream effector of the Hippo pathway, was significantly activated in Sav1-knockout mice in vivo. An in vitro study showed that TAZ directly regulates TGF-β and TGF-β receptor II expression. Collectively, our data indicate that the Hippo-Salvador pathway plays a role in the pathogenesis of TIF and that regulating this pathway may be a therapeutic strategy for reducing TIF. PMID:27550469

  6. Regulation of ERBB3/HER3 signaling in cancer

    PubMed Central

    Mujoo, Kalpana; Choi, Byung-Kwon; Huang, Zhao; Zhang, Ningyan; An, Zhiqiang

    2014-01-01

    ERBB3/HER3 is emerging as a molecular target for various cancers. HER3 is overexpressed and activated in a number of cancer types under the conditions of acquired resistance to other HER family therapeutic interventions such as tyrosine kinase inhibitors and antibody therapies. Regulation of the HER3 expression and signaling involves numerous HER3 interacting proteins. These proteins include PI3K, Shc, and E3 ubiquitin ligases NEDD4 and Nrdp1. Furthermore, recent identification of a number of HER3 oncogenic mutations in colon and gastric cancers elucidate the role of HER3 in cancer development. Despite the strong evidence regarding the role of HER3 in cancer, the current understanding of the regulation of HER3 expression and activation requires additional research. Moreover, the lack of biomarkers for HER3-driven cancer poses a big challenge for the clinical development of HER3 targeting antibodies. Therefore, a better understanding of HER3 regulation should improve the strategies to therapeutically target HER3 for cancer therapy. PMID:25400118

  7. Signal detection using the radial basis function coupled map lattice.

    PubMed

    Leung, H; Hennessey, G; Drosopoulos, A

    2000-01-01

    Conventional detection methods used in current marine radar systems do not perform efficiently in detecting small targets embedded in a clutter environment. Based on a recent observation that sea clutter, radar echoes from a sea surface, is chaotic rather than random, we propose using a spatial temporal predictor to reconstruct the chaotic dynamic of sea clutter because electromagnetic wave scattering is a spatial temporal phenomenon which is physically modeled by partial differential equations. The spatial temporal predictor used here is called radial basis function coupled map lattice (RBF-CML) which uses a linear combiner to fuse either measurements in different spatial domains for an RBF prediction or predictions from several RBF nets operated on different spatial regions. Using real-life radar data, it is shown that the RBF-CML is an effective method to reconstruct the sea clutter dynamic. The RBF-CML predictor is then applied to detect small targets in sea clutter using the constant false alarm rate (CFAR) principle. The spatial temporal approach is shown, both theoretically and experimentally, to be superior to a conventional CFAR detector.

  8. Comparison of Signals from Gravitational Wave Detectors with Instantaneous Time-Frequency Maps

    NASA Technical Reports Server (NTRS)

    Stroeer, A.; Blackburn, L.; Camp, J.

    2011-01-01

    Gravitational wave astronomy relies on the use of multiple detectors, so that coincident detections may distinguish real signals from instrumental artifacts, and also so that relative timing of signals can provide the sky position of sources. We show that the comparison of instantaneous time-frequency and time-amplitude maps provided by the Hilbert-Huang Transform (HHT) can be used effectively for relative signal timing of common signals, to discriminate between the case of identical coincident signals and random noise coincidences and to provide a classification of signals based on their time-frequency trajectories. The comparison is done with a X(sup 2) goodness-offit method which includes contributions from both the instantaneous amplitude and frequency components of the HHT to match two signals in the time domain. This approach naturally allows the analysis of waveforms with strong frequency modulation.

  9. Comparison of signals from gravitational wave detectors with instantaneous time-frequency maps

    NASA Astrophysics Data System (ADS)

    Stroeer, A.; Blackburn, L.; Camp, J.

    2011-08-01

    Gravitational wave astronomy relies on the use of multiple detectors, so that coincident detections may distinguish real signals from instrumental artifacts, and also so that relative timing of signals can provide the sky position of sources. We show that the comparison of instantaneous time-frequency and time-amplitude maps provided by the Hilbert-Huang Transform (HHT) can be used effectively for relative signal timing of common signals, to discriminate between the case of identical coincident signals and random noise coincidences and to provide a classification of signals based on their time-frequency trajectories. The comparison is done with a χ2 goodness-of-fit method which includes contributions from both the instantaneous amplitude and frequency components of the HHT to match two signals in the time domain. This approach naturally allows the analysis of waveforms with strong frequency modulation.

  10. Regulation of Cell Contraction and Membrane Ruffling by Distinct Signals in Migratory Cells

    PubMed Central

    Cheresh, David A.; Leng, Jie; Klemke, Richard L.

    1999-01-01

    Cell migration and wound contraction requires assembly of actin into a functional myosin motor unit capable of generating force. However, cell migration also involves formation of actin-containing membrane ruffles. Evidence is provided that actin-myosin assembly and membrane ruffling are regulated by distinct signaling pathways in the migratory cell. Interaction of cells with extracellular matrix proteins or cytokines promote cell migration through activation of the MAP kinases ERK1 and ERK2 as well as the molecular coupling of the adaptor proteins p130CAS and c-CrkII. ERK signaling is independent of CAS/Crk coupling and regulates myosin light chain phosphorylation leading to actin-myosin assembly during cell migration and cell-mediated contraction of a collagen matrix. In contrast, membrane ruffling, but not cell contraction, requires Rac GTPase activity and the formation of a CAS/Crk complex that functions in the context of the Rac activating protein DOCK180. Thus, during cell migration ERK and CAS/Crk coupling operate as components of distinct signaling pathways that control actin assembly into myosin motors and membrane ruffles, respectively. PMID:10477763

  11. Regulation of T cell receptor complex-mediated signaling by ubiquitin and ubiquitin-like modifications

    PubMed Central

    Friend, Samantha F; Deason-Towne, Francina; Peterson, Lisa K; Berger, Allison J; Dragone, Leonard L

    2014-01-01

    Post-translational protein modifications are a dynamic method of regulating protein function in response to environmental signals. As with any cellular process, T cell receptor (TCR) complex-mediated signaling is highly regulated, since the strength and duration of TCR-generated signals governs T cell development and activation. While regulation of TCR complex-mediated signaling by phosphorylation has been well studied, regulation by ubiquitin and ubiquitin-like modifiers is still an emerging area of investigation. This review will examine how ubiquitin, E3 ubiquitin ligases, and other ubiquitin-like modifications such as SUMO and NEDD8 regulate TCR complex-mediated signaling. PMID:25628960

  12. Regulation of T cell receptor complex-mediated signaling by ubiquitin and ubiquitin-like modifications.

    PubMed

    Friend, Samantha F; Deason-Towne, Francina; Peterson, Lisa K; Berger, Allison J; Dragone, Leonard L

    2014-01-01

    Post-translational protein modifications are a dynamic method of regulating protein function in response to environmental signals. As with any cellular process, T cell receptor (TCR) complex-mediated signaling is highly regulated, since the strength and duration of TCR-generated signals governs T cell development and activation. While regulation of TCR complex-mediated signaling by phosphorylation has been well studied, regulation by ubiquitin and ubiquitin-like modifiers is still an emerging area of investigation. This review will examine how ubiquitin, E3 ubiquitin ligases, and other ubiquitin-like modifications such as SUMO and NEDD8 regulate TCR complex-mediated signaling.

  13. Regulation of T cell receptor complex-mediated signaling by ubiquitin and ubiquitin-like modifications.

    PubMed

    Friend, Samantha F; Deason-Towne, Francina; Peterson, Lisa K; Berger, Allison J; Dragone, Leonard L

    2014-01-01

    Post-translational protein modifications are a dynamic method of regulating protein function in response to environmental signals. As with any cellular process, T cell receptor (TCR) complex-mediated signaling is highly regulated, since the strength and duration of TCR-generated signals governs T cell development and activation. While regulation of TCR complex-mediated signaling by phosphorylation has been well studied, regulation by ubiquitin and ubiquitin-like modifiers is still an emerging area of investigation. This review will examine how ubiquitin, E3 ubiquitin ligases, and other ubiquitin-like modifications such as SUMO and NEDD8 regulate TCR complex-mediated signaling. PMID:25628960

  14. Hydrogen peroxide sensing, signaling and regulation of transcription factors

    PubMed Central

    Marinho, H. Susana; Real, Carla; Cyrne, Luísa; Soares, Helena; Antunes, Fernando

    2014-01-01

    The regulatory mechanisms by which hydrogen peroxide (H2O2) modulates the activity of transcription factors in bacteria (OxyR and PerR), lower eukaryotes (Yap1, Maf1, Hsf1 and Msn2/4) and mammalian cells (AP-1, NRF2, CREB, HSF1, HIF-1, TP53, NF-κB, NOTCH, SP1 and SCREB-1) are reviewed. The complexity of regulatory networks increases throughout the phylogenetic tree, reaching a high level of complexity in mammalians. Multiple H2O2 sensors and pathways are triggered converging in the regulation of transcription factors at several levels: (1) synthesis of the transcription factor by upregulating transcription or increasing both mRNA stability and translation; (ii) stability of the transcription factor by decreasing its association with the ubiquitin E3 ligase complex or by inhibiting this complex; (iii) cytoplasm–nuclear traffic by exposing/masking nuclear localization signals, or by releasing the transcription factor from partners or from membrane anchors; and (iv) DNA binding and nuclear transactivation by modulating transcription factor affinity towards DNA, co-activators or repressors, and by targeting specific regions of chromatin to activate individual genes. We also discuss how H2O2 biological specificity results from diverse thiol protein sensors, with different reactivity of their sulfhydryl groups towards H2O2, being activated by different concentrations and times of exposure to H2O2. The specific regulation of local H2O2 concentrations is also crucial and results from H2O2 localized production and removal controlled by signals. Finally, we formulate equations to extract from typical experiments quantitative data concerning H2O2 reactivity with sensor molecules. Rate constants of 140 M−1 s−1 and ≥1.3 × 103 M−1 s−1 were estimated, respectively, for the reaction of H2O2 with KEAP1 and with an unknown target that mediates NRF2 protein synthesis. In conclusion, the multitude of H2O2 targets and mechanisms provides an opportunity for highly

  15. Automated Coronal Seismology: Curvelet Characterization of Probability Maps of Image Data with Oscillatory Signal

    NASA Astrophysics Data System (ADS)

    Young, C.; Ireland, J.

    2010-12-01

    Automated coronal seismology will require measurements of the structure that supports an oscillatory signal; for example, a measurement of the loop length of a transversely oscillating loop can be used to estimate the coronal magnetic field (Nakariakov& Ofman 2001). One of the results from the recently published Bayesian probability based automated oscillation detection algorithm (Ireland et al., 2010) is a probability map. This is an image of the probability that each pixel from a set of images contains an oscillatory signal. A map from a significant detection contains one or more clusters of high probability pixels dispersed amongst mostly pixels of low probability. These low probability pixels amount to noise while the clusters of high probability are the desired signal. A visual inspection of the probability maps that contain significant signal reveal that the clusters of pixels contain structure that corresponds to physical regions in the original images i.e. oscillating loops. A necessary step for using these oscillation probability maps is to extract and characterize these high probability regions. A natural choice for an appropriate representation of these structures especially given their corresponds to real extended features such as loops is the curvelet transform (Candes and Donoho, 1999 and Candes et al., 2005). In this work we present a preliminary analysis of these probability maps using curvelets to isolate and characterize regions of high probability. The suitability of this technique for the pipeline processing of Solar Dynamics Observatory data is also discussed.

  16. FGF2 and insulin signaling converge to regulate cyclin D expression in multipotent neural stem cells.

    PubMed

    Adepoju, Adedamola; Micali, Nicola; Ogawa, Kazuya; Hoeppner, Daniel J; McKay, Ronald D G

    2014-03-01

    The ex vivo expansion of stem cells is making major contribution to biomedical research. The multipotent nature of neural precursors acutely isolated from the developing central nervous system has been established in a series of studies. Understanding the mechanisms regulating cell expansion in tissue culture would support their expanded use either in cell therapies or to define disease mechanisms. Basic fibroblast growth factor (FGF2) and insulin, ligands for tyrosine kinase receptors, are sufficient to sustain neural stem cells (NSCs) in culture. Interestingly, real-time imaging shows that these cells become multipotent every time they are passaged. Here, we analyze the role of FGF2 and insulin in the brief period when multipotent cells are present. FGF2 signaling results in the phosphorylation of Erk1/2, and activation of c-Fos and c-Jun that lead to elevated cyclin D mRNA levels. Insulin signals through the PI3k/Akt pathway to regulate cyclins at the post-transcriptional level. This precise Boolean regulation extends our understanding of the proliferation of multipotent NSCs and provides a basis for further analysis of proliferation control in the cell states defined by real-time mapping of the cell lineages that form the central nervous system.

  17. Flexible generation of optical nonuniform bit-mapping signal based on InP transmitter module.

    PubMed

    Liu, Bo; Zhang, Lijia; Xin, Xiangjun; Liu, Lei

    2014-01-15

    Flexible generation of an optical nonuniform bit-mapping signal based on an InP transmitter module is demonstrated. It can realize flexible bit mapping through the photonic modulation method, which can break the limitations of an electrical digital-to-analog convertor and field-programmable gate array. This module has potential to easily increase the signal rate or refine the granularity without electronics, which indicates it may be a future application to replace the traditional transmitter. The feasibility and performance of the proposed scheme are demonstrated in the experiment.

  18. Extracellular Signal-Regulated Kinase-2 within the Ventral Tegmental Area Regulates Responses to Stress

    PubMed Central

    Iñiguez, Sergio D.; Vialou, Vincent; Warren, Brandon L.; Cao, Jun-Li; Alcantara, Lyonna F.; Davis, Lindsey C.; Manojlovic, Zarko; Neve, Rachael L.; Russo, Scott J.; Han, Ming-Hu; Nestler, Eric J.; Bolaños-Guzmán, Carlos A.

    2010-01-01

    Neurotrophic factors and their signaling pathways have been implicated in the neurobiological adaptations in response to stress and the regulation of mood-related behaviors. A candidate signaling molecule implicated in mediating these cellular responses is the extracellular signal-regulated kinase (ERK1/2), although its functional role in mood regulation remains to be fully elucidated. Here we show that acute (1 d) or chronic (4 weeks) exposure to unpredictable stress increases phosphorylation of ERK1/2 and of two downstream targets (ribosomal S6 kinase and mitogen- and stress-activated protein kinase 1) within the ventral tegmental area (VTA), an important substrate for motivated behavior and mood regulation. Using herpes simplex virus-mediated gene transfer to assess the functional significance of this ERK induction, we show that overexpressing ERK2 within the VTA increases susceptibility to stress as measured in the forced swim test, responses to unconditioned nociceptive stimuli, and elevated plus maze in Sprague Dawley male rats, and in the tail suspension test and chronic social defeat stress procedure in C57BL/6 male mice. In contrast, blocking ERK2 activity in the VTA produces stress-resistant behavioral responses in these same assays and also blocks a chronic stress-induced reduction in sucrose preference. The effects induced by ERK2 blockade were accompanied by decreases in the firing frequency of VTA dopamine neurons, an important electrophysiological hallmark of resilient-like behavior. Together, these results strongly implicate a role for ERK2 signaling in the VTA as a key modulator of responsiveness to stress and mood-related behaviors. PMID:20519540

  19. The regulation of oncogenic Ras/ERK signalling by dual-specificity mitogen activated protein kinase phosphatases (MKPs).

    PubMed

    Kidger, Andrew M; Keyse, Stephen M

    2016-02-01

    Dual-specificity MAP kinase (MAPK) phosphatases (MKPs or DUSPs) are well-established negative regulators of MAPK signalling in mammalian cells and tissues. By virtue of their differential subcellular localisation and ability to specifically recognise, dephosphorylate and inactivate different MAPK isoforms, they are key spatiotemporal regulators of pathway activity. Furthermore, as they are transcriptionally regulated as downstream targets of MAPK signalling they can either act as classical negative feedback regulators or mediate cross talk between distinct MAPK pathways. Because MAPKs and particularly Ras/ERK signalling are implicated in cancer initiation and development, the observation that MKPs are abnormally regulated in human tumours has been interpreted as evidence that these enzymes can either suppress or promote carcinogenesis. However, definitive evidence of such roles has been lacking. Here we review recent work based on the use of mouse models, biochemical studies and clinical data that demonstrate key roles for MKPs in modulating the oncogenic potential of Ras/ERK signalling and also indicate that these enzymes may play a role in the response of tumours to certain anticancer drugs. Overall, this work reinforces the importance of negative regulatory mechanisms in modulating the activity of oncogenic MAPK signalling and indicates that MKPs may provide novel targets for therapeutic intervention in cancer. PMID:26791049

  20. The ubiquitin-proteasome system regulates plant hormone signaling

    PubMed Central

    Santner, Aaron; Estelle, Mark

    2011-01-01

    SUMMARY Plants utilize the ubiquitin-proteasome system (UPS) to modulate nearly every aspect of growth and development. Ubiquitin is covalently attached to target proteins through the action of three enzymes known as E1, E2, and E3. The ultimate outcome of this post-translational modification depends on the nature of the ubiquitin linkage and the extent of polyubiquitination. In most cases, ubiquitination results in degradation of the target protein in the 26S proteasome. During the last 10 years it has become clear that the UPS plays a prominent regulatory role in hormone biology. E3 ubiquitin ligases in particular actively participate in hormone perception, de-repression of hormone signaling pathways, degradation of hormone specific transcription factors, and regulation of hormone biosynthesis. It is certain that additional functions will be discovered as more of the nearly 1200 potential E3s in plants are elucidated. PMID:20409276

  1. Regulation of Ca2+ Signaling in Pulmonary Hypertension

    PubMed Central

    Won, Jun Yeon

    2013-01-01

    Understanding the cellular and molecular mechanisms involved in the development and progression of pulmonary hypertension (PH) remains imperative if we are to successfully improve the quality of life and life span of patients with the disease. A whole plethora of mechanisms are associated with the development and progression of PH. Such complexity makes it difficult to isolate one particular pathway to target clinically. Changes in intracellular free calcium concentration, the most common intracellular second messenger, can have significant impact in defining the pathogenic mechanisms leading to its development and persistence. Signaling pathways leading to the elevation of [Ca2+]cyt contribute to pulmonary vasoconstriction, excessive proliferation of smooth muscle cells and ultimately pulmonary vascular remodeling. This current review serves to summarize the some of the most recent advances in the regulation of calcium during pulmonary hypertension. PMID:23439762

  2. Small G proteins and their regulators in cellular signalling.

    PubMed

    Csépányi-Kömi, Roland; Lévay, Magdolna; Ligeti, Erzsébet

    2012-04-28

    Small molecular weight GTPases (small G proteins) are essential in the transduction of signals from different plasma membrane receptors. Due to their endogenous GTP-hydrolyzing activity, these proteins function as time-dependent biological switches controlling diverse cellular functions including cell shape and migration, cell proliferation, gene transcription, vesicular transport and membrane-trafficking. This review focuses on endocrine diseases linked to small G proteins. We provide examples for the regulation of the activity of small G proteins by various mechanisms such as posttranslational modifications, guanine nucleotide exchange factors (GEFs), GTPase activating proteins (GAPs) or guanine nucleotide dissociation inhibitors (GDIs). Finally we summarize endocrine diseases where small G proteins or their regulatory proteins have been revealed as the cause.

  3. Regulation of organismal proteostasis by trans-cellular chaperone signaling

    PubMed Central

    van Oosten-Hawle, Patricija; Porter, Robert S.; Morimoto, Richard I.

    2013-01-01

    Summary A major challenge for metazoans is to ensure that different tissues each expressing distinctive proteomes are, nevertheless, well protected at an organismal level from proteotoxic stress. We have examined this and show that expression of endogenous metastable protein sensors in muscle cells induces a systemic stress response throughout multiple tissues of C. elegans. Suppression of misfolding in muscle cells can be achieved not only by enhanced expression of HSP90 in muscle cells, but as effective by elevated expression of HSP90 in intestine or neuronal cells. This cell-non-autonomous control of HSP90 expression relies upon transcriptional feedback between somatic tissues that is regulated by the FoxA transcription factor PHA-4. This trans-cellular chaperone signaling response maintains organismal proteostasis when challenged by a local tissue imbalance in folding and provides the basis for a novel form of organismal stress sensing surveillance. PMID:23746847

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

    PubMed

    Hopkins, John

    2002-09-10

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

  5. EGFR/Ras Signaling Controls Drosophila Intestinal Stem Cell Proliferation via Capicua-Regulated Genes.

    PubMed

    Jin, Yinhua; Ha, Nati; Forés, Marta; Xiang, Jinyi; Gläßer, Christine; Maldera, Julieta; Jiménez, Gerardo; Edgar, Bruce A

    2015-12-01

    Epithelial renewal in the Drosophila intestine is orchestrated by Intestinal Stem Cells (ISCs). Following damage or stress the intestinal epithelium produces ligands that activate the epidermal growth factor receptor (EGFR) in ISCs. This promotes their growth and division and, thereby, epithelial regeneration. Here we demonstrate that the HMG-box transcriptional repressor, Capicua (Cic), mediates these functions of EGFR signaling. Depleting Cic in ISCs activated them for division, whereas overexpressed Cic inhibited ISC proliferation and midgut regeneration. Epistasis tests showed that Cic acted as an essential downstream effector of EGFR/Ras signaling, and immunofluorescence showed that Cic's nuclear localization was regulated by EGFR signaling. ISC-specific mRNA expression profiling and DNA binding mapping using DamID indicated that Cic represses cell proliferation via direct targets including string (Cdc25), Cyclin E, and the ETS domain transcription factors Ets21C and Pointed (pnt). pnt was required for ISC over-proliferation following Cic depletion, and ectopic pnt restored ISC proliferation even in the presence of overexpressed dominant-active Cic. These studies identify Cic, Pnt, and Ets21C as critical downstream effectors of EGFR signaling in Drosophila ISCs.

  6. Differential regulation of Tec1 by Fus3 and Kss1 confers signaling specificity in yeast development.

    PubMed

    Brückner, Stefan; Köhler, Tim; Braus, Gerhard H; Heise, Barbara; Bolte, Melanie; Mösch, Hans-Ulrich

    2004-12-01

    Transcriptional regulation by mitogen-activated protein (MAP) kinase signaling cascades is a major control mechanism for eukaryotic development. In budding yeast, Fus3 and Kss1 are two MAP kinases that control two distinct developmental programs-mating and invasive growth. We investigated whether signal-specific activation of mating and invasive growth involves regulation of the transcription factor Tec1 by Fus3 and Kss1. We present evidence that, during mating, Fus3 phosphorylates Tec1 to downregulate this invasive growth-specific transcription factor and its target genes. This function of Fus3 is essential for correct execution of the mating program and is not shared by Kss1. We find that Kss1 controls the activity of Tec1 mainly during invasive growth by control of TEC1 gene expression. Our study suggests that signaling specificity can arise from differential regulation of a single transcription factor by two MAP kinases with shared functions in distinct developmental programs. PMID:15558284

  7. Repair Injured Heart by Regulating Cardiac Regenerative Signals

    PubMed Central

    Wang, Lei; Paul, Christian

    2016-01-01

    Cardiac regeneration is a homeostatic cardiogenic process by which the sections of malfunctioning adult cardiovascular tissues are repaired and renewed employing a combination of both cardiomyogenesis and angiogenesis. Unfortunately, while high-quality regeneration can be performed in amphibians and zebrafish hearts, mammalian hearts do not respond in kind. Indeed, a long-term loss of proliferative capacity in mammalian adult cardiomyocytes in combination with dysregulated induction of tissue fibrosis impairs mammalian endogenous heart regenerative capacity, leading to deleterious cardiac remodeling at the end stage of heart failure. Interestingly, several studies have demonstrated that cardiomyocyte proliferation capacity is retained in mammals very soon after birth, and cardiac regeneration potential is correspondingly preserved in some preadolescent vertebrates after myocardial infarction. There is therefore great interest in uncovering the molecular mechanisms that may allow heart regeneration during adult stages. This review will summarize recent findings on cardiac regenerative regulatory mechanisms, especially with respect to extracellular signals and intracellular pathways that may provide novel therapeutics for heart diseases. Particularly, both in vitro and in vivo experimental evidences will be presented to highlight the functional role of these signaling cascades in regulating cardiomyocyte proliferation, cardiomyocyte growth, and maturation, with special emphasis on their responses to heart tissue injury. PMID:27799944

  8. A cyclic GMP-dependent signalling pathway regulates bacterial phytopathogenesis.

    PubMed

    An, Shi-Qi; Chin, Ko-Hsin; Febrer, Melanie; McCarthy, Yvonne; Yang, Jauo-Guey; Liu, Chung-Liang; Swarbreck, David; Rogers, Jane; Maxwell Dow, J; Chou, Shan-Ho; Ryan, Robert P

    2013-09-11

    Cyclic guanosine 3',5'-monophosphate (cyclic GMP) is a second messenger whose role in bacterial signalling is poorly understood. A genetic screen in the plant pathogen Xanthomonas campestris (Xcc) identified that XC_0250, which encodes a protein with a class III nucleotidyl cyclase domain, is required for cyclic GMP synthesis. Purified XC_0250 was active in cyclic GMP synthesis in vitro. The linked gene XC_0249 encodes a protein with a cyclic mononucleotide-binding (cNMP) domain and a GGDEF diguanylate cyclase domain. The activity of XC_0249 in cyclic di-GMP synthesis was enhanced by addition of cyclic GMP. The isolated cNMP domain of XC_0249 bound cyclic GMP and a structure-function analysis, directed by determination of the crystal structure of the holo-complex, demonstrated the site of cyclic GMP binding that modulates cyclic di-GMP synthesis. Mutation of either XC_0250 or XC_0249 led to a reduced virulence to plants and reduced biofilm formation in vitro. These findings describe a regulatory pathway in which cyclic GMP regulates virulence and biofilm formation through interaction with a novel effector that directly links cyclic GMP and cyclic di-GMP signalling.

  9. Integrin signalling regulates YAP and TAZ to control skin homeostasis

    PubMed Central

    Elbediwy, Ahmed; Vincent-Mistiaen, Zoé I.; Spencer-Dene, Bradley; Stone, Richard K.; Boeing, Stefan; Wculek, Stefanie K.; Cordero, Julia; Tan, Ee H.; Ridgway, Rachel; Brunton, Val G.; Sahai, Erik; Gerhardt, Holger; Behrens, Axel; Malanchi, Ilaria; Sansom, Owen J.; Thompson, Barry J.

    2016-01-01

    ABSTRACT The skin is a squamous epithelium that is continuously renewed by a population of basal layer stem/progenitor cells and can heal wounds. Here, we show that the transcription regulators YAP and TAZ localise to the nucleus in the basal layer of skin and are elevated upon wound healing. Skin-specific deletion of both YAP and TAZ in adult mice slows proliferation of basal layer cells, leads to hair loss and impairs regeneration after wounding. Contact with the basal extracellular matrix and consequent integrin-Src signalling is a key determinant of the nuclear localisation of YAP/TAZ in basal layer cells and in skin tumours. Contact with the basement membrane is lost in differentiating daughter cells, where YAP and TAZ become mostly cytoplasmic. In other types of squamous epithelia and squamous cell carcinomas, a similar control mechanism is present. By contrast, columnar epithelia differentiate an apical domain that recruits CRB3, Merlin (also known as NF2), KIBRA (also known as WWC1) and SAV1 to induce Hippo signalling and retain YAP/TAZ in the cytoplasm despite contact with the basal layer extracellular matrix. When columnar epithelial tumours lose their apical domain and become invasive, YAP/TAZ becomes nuclear and tumour growth becomes sensitive to the Src inhibitor Dasatinib. PMID:26989177

  10. Ethylene Signaling Influences Light-Regulated Development in Pea.

    PubMed

    Weller, James L; Foo, Eloise M; Hecht, Valérie; Ridge, Stephen; Vander Schoor, Jacqueline K; Reid, James B

    2015-09-01

    Plant responses to light involve a complex network of interactions among multiple plant hormones. In a screen for mutants showing altered photomorphogenesis under red light, we identified a mutant with dramatically enhanced leaf expansion and delayed petal senescence. We show that this mutant exhibits reduced sensitivity to ethylene and carries a nonsense mutation in the single pea (Pisum sativum) ortholog of the ethylene signaling gene ETHYLENE INSENSITIVE2 (EIN2). Consistent with this observation, the ein2 mutation rescues the previously described effects of ethylene overproduction in mature phytochrome-deficient plants. In seedlings, ein2 confers a marked increase in leaf expansion under monochromatic red, far-red, or blue light, and interaction with phytochromeA, phytochromeB, and long1 mutants confirms that ein2 enhances both phytochrome- and cryptochrome-dependent responses in a LONG1-dependent manner. In contrast, minimal effects of ein2 on seedling development in darkness or high-irradiance white light show that ethylene is not limiting for development under these conditions. These results indicate that ethylene signaling constrains leaf expansion during deetiolation in pea and provide further evidence that down-regulation of ethylene production may be an important component mechanism in the broader control of photomorphogenic development by phytochrome and cryptochrome.

  11. Hedgehog signaling regulates gene expression in planarian glia

    PubMed Central

    Wang, Irving E; Lapan, Sylvain W; Scimone, M Lucila; Clandinin, Thomas R; Reddien, Peter W

    2016-01-01

    Hedgehog signaling is critical for vertebrate central nervous system (CNS) development, but its role in CNS biology in other organisms is poorly characterized. In the planarian Schmidtea mediterranea, hedgehog (hh) is expressed in medial cephalic ganglia neurons, suggesting a possible role in CNS maintenance or regeneration. We performed RNA sequencing of planarian brain tissue following RNAi of hh and patched (ptc), which encodes the Hh receptor. Two misregulated genes, intermediate filament-1 (if-1) and calamari (cali), were expressed in a previously unidentified non-neural CNS cell type. These cells expressed orthologs of astrocyte-associated genes involved in neurotransmitter uptake and metabolism, and extended processes enveloping regions of high synapse concentration. We propose that these cells are planarian glia. Planarian glia were distributed broadly, but only expressed if-1 and cali in the neuropil near hh+ neurons. Planarian glia and their regulation by Hedgehog signaling present a novel tractable system for dissection of glia biology. DOI: http://dx.doi.org/10.7554/eLife.16996.001 PMID:27612382

  12. Regulation of Nuclear Localization of Signaling Proteins by Cytokinin

    SciTech Connect

    Kieber, J.J.

    2010-05-01

    Cytokinins are a class of mitogenic plant hormones that play an important role in most aspects of plant development, including shoot and root growth, vascular and photomorphogenic development and leaf senescence. A model for cytokinin perception and signaling has emerged that is similar to bacterial two-component phosphorelays. In this model, binding of cytokinin to the extracellular domain of the Arabidopsis histidine kinase (AHKs) receptors induces autophosphorylation within the intracellular histidine-kinase domain. The phosphoryl group is subsequently transferred to cytosolic Arabidopsis histidine phosphotransfer proteins (AHPs), which have been suggested to translocate to the nucleus in response to cytokinin treatment, where they then transfer the phosphoryl group to nuclear-localized response regulators (Type-A and Type-B ARRs). We examined the effects of cytokinin on AHP subcellular localization in Arabidopsis and, contrary to expectations, the AHPs maintained a constant nuclear/cytosolic distribution following cytokinin treatment. Furthermore, mutation of the conserved phosphoacceptor histidine residue of the AHP, as well as disruption of multiple cytokinin signaling elements, did not affect the subcellular localization of the AHP proteins. Finally, we present data indicating that AHPs maintain a nuclear/cytosolic distribution by balancing active transport into and out of the nucleus. Our findings suggest that the current models indicating relocalization of AHP protein into the nucleus in response to cytokinin are incorrect. Rather, AHPs actively maintain a consistent nuclear/cytosolic distribution regardless of the status of the cytokinin response pathway.

  13. Basic amino-acid side chains regulate transmembrane integrin signalling.

    PubMed

    Kim, Chungho; Schmidt, Thomas; Cho, Eun-Gyung; Ye, Feng; Ulmer, Tobias S; Ginsberg, Mark H

    2011-12-18

    Side chains of Lys/Arg near transmembrane domain (TMD) membrane-water interfaces can 'snorkel', placing their positive charge near negatively charged phospholipid head groups; however, snorkelling's functional effects are obscure. Integrin β TMDs have such conserved basic amino acids. Here we use NMR spectroscopy to show that integrin β(3)(Lys 716) helps determine β(3) TMD topography. The α(ΙΙb)β(3) TMD structure indicates that precise β(3) TMD crossing angles enable the assembly of outer and inner membrane 'clasps' that hold the αβ TMD together to limit transmembrane signalling. Mutation of β(3)(Lys 716) caused dissociation of α(ΙΙb)β(3) TMDs and integrin activation. To confirm that altered topography of β(3)(Lys 716) mutants activated α(ΙΙb)β(3), we used directed evolution of β(3)(K716A) to identify substitutions restoring default state. Introduction of Pro(711) at the midpoint of β(3) TMD (A711P) increased α(ΙΙb)β(3) TMD association and inactivated integrin α(ΙΙb)β(3)(A711P,K716A). β(3)(Pro 711) introduced a TMD kink of 30 ± 1° precisely at the border of the outer and inner membrane clasps, thereby decoupling the tilt between these segments. Thus, widely occurring snorkelling residues in TMDs can help maintain TMD topography and membrane-embedding, thereby regulating transmembrane signalling.

  14. SeqGL Identifies Context-Dependent Binding Signals in Genome-Wide Regulatory Element Maps.

    PubMed

    Setty, Manu; Leslie, Christina S

    2015-05-01

    Genome-wide maps of transcription factor (TF) occupancy and regions of open chromatin implicitly contain DNA sequence signals for multiple factors. We present SeqGL, a novel de novo motif discovery algorithm to identify multiple TF sequence signals from ChIP-, DNase-, and ATAC-seq profiles. SeqGL trains a discriminative model using a k-mer feature representation together with group lasso regularization to extract a collection of sequence signals that distinguish peak sequences from flanking regions. Benchmarked on over 100 ChIP-seq experiments, SeqGL outperformed traditional motif discovery tools in discriminative accuracy. Furthermore, SeqGL can be naturally used with multitask learning to identify genomic and cell-type context determinants of TF binding. SeqGL successfully scales to the large multiplicity of sequence signals in DNase- or ATAC-seq maps. In particular, SeqGL was able to identify a number of ChIP-seq validated sequence signals that were not found by traditional motif discovery algorithms. Thus compared to widely used motif discovery algorithms, SeqGL demonstrates both greater discriminative accuracy and higher sensitivity for detecting the DNA sequence signals underlying regulatory element maps. SeqGL is available at http://cbio.mskcc.org/public/Leslie/SeqGL/. PMID:26016777

  15. Structure, functional regulation and signaling properties of Rap2B

    PubMed Central

    QU, DEBAO; HUANG, HUI; DI, JIEHUI; GAO, KEYU; LU, ZHENG; ZHENG, JUNNIAN

    2016-01-01

    The Ras family small guanosine 5′-triphosphate (GTP)-binding protein Rap2B is is a member of the Ras oncogene family and a novel target of p53 that regulates the p53-mediated pro-survival function of cells. The Rap2B protein shares ~90% homology with Rap2A, and its sequence is 70% identical to other members of the Rap family such as RaplA and RaplB. As a result, Rap2B has been theorized to have similar signaling effectors to the GTPase-binding protein Rap, which mediates various biological functions, including the regulation of sterile 20/mitogen-activated proteins. Since its identification in the early 1990s, Rap2B has elicited a considerable interest. Numerous studies indicate that Rap2B exerts specific biological functions, including binding and stimulating phospholipase C-ε and interferon-γ. In addition, downregulation of Rap2B affects the growth of melanoma cells. The present review summarizes the possible effectors and biological functions of Rap2B. Increasing evidence clearly supports the association between Rap2B function and tumor development. Therefore, it is conceivable that anticancer drugs targeting Rap2B may be generated as novel therapies against cancer. PMID:27073477

  16. TLR signals posttranscriptionally regulate the cytokine trafficking mediator sortilin

    PubMed Central

    Yabe-Wada, Toshiki; Matsuba, Shintaro; Takeda, Kazuya; Sato, Tetsuya; Suyama, Mikita; Ohkawa, Yasuyuki; Takai, Toshiyuki; Shi, Haifeng; Philpott, Caroline C.; Nakamura, Akira

    2016-01-01

    Regulating the transcription, translation and secretion of cytokines is crucial for controlling the appropriate balance of inflammation. Here we report that the sorting receptor sortilin plays a key role in cytokine production. We observed interactions of sortilin with multiple cytokines including IFN-α, and sortilin depletion in plasmacytoid dendritic cells (pDCs) led to a reduction of IFN-α secretion, suggesting a pivotal role of sortilin in the exocytic trafficking of IFN-α in pDCs. Moreover, sortilin mRNA was degraded posttranscriptionally upon stimulation with various TLR ligands. Poly-rC-binding protein 1 (PCBP1) recognized the C-rich element (CRE) in the 3′ UTR of sortilin mRNA, and depletion of PCBP1 enhanced the degradation of sortilin transcripts, suggesting that PCBP1 can act as a trans-acting factor to stabilize sortilin transcripts. The nucleotide-binding ability of PCBP1 was impaired by zinc ions and alterations of intracellular zinc affect sortilin expression. PCBP1 may therefore control the stability of sortilin transcripts by sensing intracellular zinc levels. Collectively, our findings provide insights into the posttranslational regulation of cytokine production through the posttranscriptional control of sortilin expression by TLR signals. PMID:27220277

  17. Sensor–response regulator interactions in a cross-regulated signal transduction network

    PubMed Central

    Huynh, TuAnh Ngoc; Chen, Li-Ling

    2015-01-01

    Two-component signal transduction involves phosphoryl transfer between a histidine kinase sensor and a response regulator effector. The nitrate-responsive two-component signal transduction systems in Escherichia coli represent a paradigm for a cross-regulation network, in which the paralogous sensor–response regulator pairs, NarX–NarL and NarQ–NarP, exhibit both cognate (e.g. NarX–NarL) and non-cognate (e.g. NarQ–NarL) interactions to control output. Here, we describe results from bacterial adenylate cyclase two-hybrid (BACTH) analysis to examine sensor dimerization as well as interaction between sensor–response regulator cognate and non-cognate pairs. Although results from BACTH analysis indicated that the NarX and NarQ sensors interact with each other, results from intragenic complementation tests demonstrate that they do not form functional heterodimers. Additionally, intragenic complementation shows that both NarX and NarQ undergo intermolecular autophosphorylation, deviating from the previously reported correlation between DHp (dimerization and histidyl phosphotransfer) domain loop handedness and autophosphorylation mode. Results from BACTH analysis revealed robust interactions for the NarX–NarL, NarQ–NarL and NarQ–NarP pairs but a much weaker interaction for the NarX–NarP pair. This demonstrates that asymmetrical cross-regulation results from differential binding affinities between different sensor–regulator pairs. Finally, results indicate that the NarL effector (DNA-binding) domain inhibits NarX–NarL interaction. Missense substitutions at receiver domain residue Ser-80 enhanced NarX–NarL interaction, apparently by destabilizing the NarL receiver–effector domain interface. PMID:25873583

  18. TIM-1 signaling in B cells regulates antibody production

    SciTech Connect

    Ma, Juan; Usui, Yoshihiko; Takeda, Kazuyoshi; Harada, Norihiro; Yagita, Hideo; Okumura, Ko; Akiba, Hisaya

    2011-03-11

    Highlights: {yields} TIM-1 is highly expressed on anti-IgM + anti-CD40-stimulated B cells. {yields} Anti-TIM-1 mAb enhanced proliferation and Ig production on activated B cell in vitro. {yields} TIM-1 signaling regulates Ab production by response to TI-2 and TD antigens in vivo. -- Abstract: Members of the T cell Ig and mucin (TIM) family have recently been implicated in the control of T cell-mediated immune responses. In this study, we found TIM-1 expression on anti-IgM- or anti-CD40-stimulated splenic B cells, which was further up-regulated by the combination of anti-IgM and anti-CD40 Abs. On the other hand, TIM-1 ligand was constitutively expressed on B cells and inducible on anti-CD3{sup +} anti-CD28-stimulated CD4{sup +} T cells. In vitro stimulation of activated B cells by anti-TIM-1 mAb enhanced proliferation and expression of a plasma cell marker syndecan-1 (CD138). We further examined the effect of TIM-1 signaling on antibody production in vitro and in vivo. Higher levels of IgG2b and IgG3 secretion were detected in the culture supernatants of the anti-TIM-1-stimulated B cells as compared with the control IgG-stimulated B cells. When immunized with T-independent antigen TNP-Ficoll, TNP-specific IgG1, IgG2b, and IgG3 Abs were slightly increased in the anti-TIM-1-treated mice. When immunized with T-dependent antigen OVA, serum levels of OVA-specific IgG2b, IgG3, and IgE Abs were significantly increased in the anti-TIM-1-treated mice as compared with the control IgG-treated mice. These results suggest that TIM-1 signaling in B cells augments antibody production by enhancing B cell proliferation and differentiation.

  19. Regulation of cpg15 by signaling pathways that mediate synaptic plasticity.

    PubMed

    Fujino, Tadahiro; Lee, Wei-Chung Allen; Nedivi, Elly

    2003-11-01

    Transcriptional activation is a key link between neuronal activity and long-term synaptic plasticity. Little is known about genes responding to this activation whose products directly effect functional and structural changes at the synapse. cpg15 is an activity-regulated gene encoding a membrane-bound ligand that regulates dendritic and axonal arbor growth and synaptic maturation. We report that cpg15 is an immediate-early gene induced by Ca(2+) influx through NMDA receptors and L-type voltage-sensitive calcium channels. Activity-dependent cpg15 expression requires convergent activation of the CaM kinase and MAP kinase pathways. Although activation of PKA is not required for activity-dependent expression, cpg15 is induced by cAMP in active neurons. CREB binds the cpg15 promoter in vivo and partially regulates its activity-dependent expression. cpg15 is an effector gene that is a target for signal transduction pathways that mediate synaptic plasticity and thus may take part in an activity-regulated transcriptional program that directs long-term changes in synaptic connections. PMID:14664806

  20. Moment-to-moment brain signal variability: A next frontier in human brain mapping?

    PubMed Central

    Garrett, Douglas D.; Samanez-Larkin, Gregory R.; MacDonald, Stuart W.S.; Lindenberger, Ulman; McIntosh, Anthony R.; Grady, Cheryl L.

    2013-01-01

    Neuroscientists have long observed that brain activity is naturally variable from moment-to-moment, but neuroimaging research has largely ignored the potential importance of this phenomenon. An emerging research focus on within-person brain signal variability is providing novel insights, and offering highly predictive, complementary, and even orthogonal views of brain function in relation to human life-span development, cognitive performance, and various clinical conditions. As a result, brain signal variability is evolving as a bona fide signal of interest, and should no longer be dismissed as meaningless noise when mapping the human brain. PMID:23458776

  1. Regulator of G-protein signaling 18 integrates activating and inhibitory signaling in platelets.

    PubMed

    Gegenbauer, Kristina; Elia, Giuliano; Blanco-Fernandez, Alfonso; Smolenski, Albert

    2012-04-19

    Regulator of G-protein signaling 18 (RGS18) is a GTPase-activating protein for the G-α-q and G-α-i subunits of heterotrimeric G-proteins that turns off signaling by G-protein coupled receptors. RGS18 is highly expressed in platelets. In the present study, we show that the 14-3-3γ protein binds to phosphorylated serines 49 and 218 of RGS18. Platelet activation by thrombin, thromboxane A2, or ADP stimulates the association of 14-3-3 and RGS18, probably by increasing the phosphorylation of serine 49. In contrast, treatment of platelets with prostacyclin and nitric oxide, which trigger inhibitory cyclic nucleotide signaling involving cyclic AMP-dependent protein kinase A (PKA) and cyclic GMP-dependent protein kinase I (PKGI), induces the phosphorylation of serine 216 of RGS18 and the detachment of 14-3-3. Serine 216 phosphorylation is able to block 14-3-3 binding to RGS18 even in the presence of thrombin, thromboxane A2, or ADP. 14-3-3-deficient RGS18 is more active compared with 14-3-3-bound RGS18, leading to a more pronounced inhibition of thrombin-induced release of calcium ions from intracellular stores. Therefore, PKA- and PKGI-mediated detachment of 14-3-3 activates RGS18 to block Gq-dependent calcium signaling. These findings indicate cross-talk between platelet activation and inhibition pathways at the level of RGS18 and Gq. PMID:22234696

  2. Extracellular signal regulated kinase 5 mediates signals triggered by the novel tumor promoter palytoxin

    SciTech Connect

    Charlson, Aaron T.; Zeliadt, Nicholette A.; Wattenberg, Elizabeth V.

    2009-12-01

    Palytoxin is classified as a non-12-O-tetradecanoylphorbol-13-acetate (TPA)-type skin tumor because it does not bind to or activate protein kinase C. Palytoxin is thus a novel tool for investigating alternative signaling pathways that may affect carcinogenesis. We previously showed that palytoxin activates three major members of the mitogen activated protein kinase (MAPK) family, extracellular signal regulated kinase 1 and 2 (ERK1/2), c-Jun N-terminal kinase (JNK), and p38. Here we report that palytoxin also activates another MAPK family member, called ERK5, in HeLa cells and in keratinocytes derived from initiated mouse skin (308 cells). By contrast, TPA does not activate ERK5 in these cell lines. The major cell surface receptor for palytoxin is the Na+,K+-ATPase. Accordingly, ouabain blocked the ability of palytoxin to activate ERK5. Ouabain alone did not activate ERK5. ERK5 thus represents a divergence in the signaling pathways activated by these two agents that bind to the Na+,K+-ATPase. Cycloheximide, okadaic acid, and sodium orthovanadate did not mimic the effect of palytoxin on ERK5. These results indicate that the stimulation of ERK5 by palytoxin is not simply due to inhibition of protein synthesis or inhibition of serine/threonine or tyrosine phosphatases. Therefore, the mechanism by which palytoxin activates ERK5 differs from that by which it activates ERK1/2, JNK, and p38. Finally, studies that used pharmacological inhibitors and shRNA to block ERK5 action indicate that ERK5 contributes to palytoxin-stimulated c-Fos gene expression. These results suggest that ERK5 can act as an alternative mediator for transmitting diverse tumor promoter-stimulated signals.

  3. TRAF2 multitasking in TNF receptor-induced signaling to NF-κB, MAP kinases and cell death.

    PubMed

    Borghi, Alice; Verstrepen, Lynn; Beyaert, Rudi

    2016-09-15

    Tumor Necrosis Factor (TNF) is a potent inflammatory cytokine that exerts its functions through the activation of two distinct receptors, TNFR1 and TNFR2. Both receptors can activate canonical NF-κB and JNK MAP kinase signaling, while TNFR2 can also activate non-canonical NF-κB signaling, leading to numerous changes in gene expression that drive inflammation, cell proliferation and cell survival. On the other hand, TNFR1 also activates signaling pathways leading to cell death by either apoptosis or necroptosis, depending on the cellular context. A key player in TNFR1- and TNFR2-induced signaling is the RING finger protein TRAF2, which is recruited to both receptors upon their stimulation. TRAF2 exerts multiple receptor-specific functions but also mediates cross-talk between TNFR1 and TNFR2, dictating the outcome of TNF stimulation. In this review, we provide an overview of the positive and negative regulatory role of TRAF2 in different TNFR1 and TNFR2 signaling pathways. We discuss the underlying molecular mechanism of action, distinguishing between TRAF2 scaffold and E3 ubiquitin ligase functions, and the regulation of TRAF2 by specific post-translational modifications. Finally, we elaborate on some possible strategies to modulate TRAF2 function in the context of therapeutic targeting in autoimmunity and cancer.

  4. TRAF2 multitasking in TNF receptor-induced signaling to NF-κB, MAP kinases and cell death.

    PubMed

    Borghi, Alice; Verstrepen, Lynn; Beyaert, Rudi

    2016-09-15

    Tumor Necrosis Factor (TNF) is a potent inflammatory cytokine that exerts its functions through the activation of two distinct receptors, TNFR1 and TNFR2. Both receptors can activate canonical NF-κB and JNK MAP kinase signaling, while TNFR2 can also activate non-canonical NF-κB signaling, leading to numerous changes in gene expression that drive inflammation, cell proliferation and cell survival. On the other hand, TNFR1 also activates signaling pathways leading to cell death by either apoptosis or necroptosis, depending on the cellular context. A key player in TNFR1- and TNFR2-induced signaling is the RING finger protein TRAF2, which is recruited to both receptors upon their stimulation. TRAF2 exerts multiple receptor-specific functions but also mediates cross-talk between TNFR1 and TNFR2, dictating the outcome of TNF stimulation. In this review, we provide an overview of the positive and negative regulatory role of TRAF2 in different TNFR1 and TNFR2 signaling pathways. We discuss the underlying molecular mechanism of action, distinguishing between TRAF2 scaffold and E3 ubiquitin ligase functions, and the regulation of TRAF2 by specific post-translational modifications. Finally, we elaborate on some possible strategies to modulate TRAF2 function in the context of therapeutic targeting in autoimmunity and cancer. PMID:26993379

  5. Mapping Cosmic Structure Using 21-cm Hydrogen Signal at Green Bank Telescope

    NASA Astrophysics Data System (ADS)

    Voytek, Tabitha; GBT 21-cm Intensity Mapping Group

    2011-05-01

    We are using the Green Bank Telescope to make 21-cm intensity maps of cosmic structure in a 0.15 Gpc^3 box at redshift of z 1. The intensity mapping technique combines the flux from many galaxies in each pixel, allowing much greater mapping speed than the traditional redshift survey. Measurement is being made at z 1 to take advantage of a window in frequency around 700 MHz where terrestrial radio frequency interference (RFI) is currently at a minimum. This minimum is due to a reallocation of this frequency band from analog television to wide area wireless internet and public service usage. We will report progress of our attempt to detect autocorrelation of the 21-cm signal. The ultimate goal of this mapping is to use Baryon Acoustic Oscillations to provide more precise constraints to dark energy models.

  6. Fluoride Induces a Volume Reduction in CA1 Hippocampal Slices Via MAP Kinase Pathway Through Volume Regulated Anion Channels

    PubMed Central

    Lee, Jaekwang; Han, Young-Eun; Favorov, Oleg; Tommerdahl, Mark; Whitsel, Barry

    2016-01-01

    Regulation of cell volume is an important aspect of cellular homeostasis during neural activity. This volume regulation is thought to be mediated by activation of specific transporters, aquaporin, and volume regulated anion channels (VRAC). In cultured astrocytes, it was reported that swelling-induced mitogen-activated protein (MAP) kinase activation is required to open VRAC, which are thought to be important in regulatory volume decrease and in the response of CNS to trauma and excitotoxicity. It has been also described that sodium fluoride (NaF), a recognized G-protein activator and protein phosphatase inhibitor, leads to a significant MAP kinase activation in endothelial cells. However, NaF's effect in volume regulation in the brain is not known yet. Here, we investigated the mechanism of NaF-induced volume change in rat and mouse hippocampal slices using intrinsic optical signal (IOS) recording, in which we measured relative changes in intracellular and extracellular volume as changes in light transmittance through brain slices. We found that NaF (1~5 mM) application induced a reduction in light transmittance (decreased volume) in CA1 hippocampus, which was completely reversed by MAP kinase inhibitor U0126 (10 µM). We also observed that NaF-induced volume reduction was blocked by anion channel blockers, suggesting that NaF-induced volume reduction could be mediated by VRAC. Overall, our results propose a novel molecular mechanism of NaF-induced volume reduction via MAP kinase signaling pathway by activation of VRAC. PMID:27122993

  7. Fluoride Induces a Volume Reduction in CA1 Hippocampal Slices Via MAP Kinase Pathway Through Volume Regulated Anion Channels.

    PubMed

    Lee, Jaekwang; Han, Young-Eun; Favorov, Oleg; Tommerdahl, Mark; Whitsel, Barry; Lee, C Justin

    2016-04-01

    Regulation of cell volume is an important aspect of cellular homeostasis during neural activity. This volume regulation is thought to be mediated by activation of specific transporters, aquaporin, and volume regulated anion channels (VRAC). In cultured astrocytes, it was reported that swelling-induced mitogen-activated protein (MAP) kinase activation is required to open VRAC, which are thought to be important in regulatory volume decrease and in the response of CNS to trauma and excitotoxicity. It has been also described that sodium fluoride (NaF), a recognized G-protein activator and protein phosphatase inhibitor, leads to a significant MAP kinase activation in endothelial cells. However, NaF's effect in volume regulation in the brain is not known yet. Here, we investigated the mechanism of NaF-induced volume change in rat and mouse hippocampal slices using intrinsic optical signal (IOS) recording, in which we measured relative changes in intracellular and extracellular volume as changes in light transmittance through brain slices. We found that NaF (1~5 mM) application induced a reduction in light transmittance (decreased volume) in CA1 hippocampus, which was completely reversed by MAP kinase inhibitor U0126 (10 µM). We also observed that NaF-induced volume reduction was blocked by anion channel blockers, suggesting that NaF-induced volume reduction could be mediated by VRAC. Overall, our results propose a novel molecular mechanism of NaF-induced volume reduction via MAP kinase signaling pathway by activation of VRAC. PMID:27122993

  8. Regulation of mesangial cell function by vasodilatory signaling molecules.

    PubMed

    Buschhausen, L; Seibold, S; Gross, O; Matthaeus, T; Weber, M; Schulze-Lohoff, E

    2001-08-15

    Proliferation of mesangial cells and expansion of mesangial matrix is a hallmark of glomerular disease leading to end-stage renal failure and requiring renal replacement therapy. Independently from the type of injury, e.g. in glomerulonephritis or diabetic nephropathy, the response to injury is remarkably uniform. Chronic glomerular disease is frequently associated with increases in systemic blood pressure and altered intraglomerular hemodynamics. Furthermore, reduction of systemic blood pressure and inhibition of the vasoconstrictor peptide angiotensin II have been shown to delay end-stage renal failure in various types of human kidney disease. Since vasoconstrictors of mesangial cells and efferent glomerular arterioli, such as angiotensin II, are thought to be detrimental for the progression of chronic glomerular disease, we propose that vasodilatory factors which antagonize the effects of angiotensin II, might have beneficial effects during the course of progressive kidney disease. To support this concept we will summarize currently available data on the role of vasodilatory signaling molecules such as natriuretic peptides (ANP, BNP and CNP), nitric oxide (NO), the prostaglandines PGE2 and prostacycline, and the purine mediator adenosine in the regulation of mesangial function.

  9. Regulation of cell signaling and apoptosis by tumor suppressor WWOX

    PubMed Central

    Lo, Jui-Yen; Chou, Ying-Tsen; Lai, Feng-Jie

    2015-01-01

    Human fragile WWOX gene encodes a tumor suppressor WW domain-containing oxidoreductase (named WWOX, FOR, or WOX1). Functional suppression of WWOX prevents apoptotic cell death induced by a variety of stress stimuli, such as tumor necrosis factor, UV radiation, and chemotherapeutic drug treatment. Loss of WWOX gene expression due to gene deletions, loss of heterozygosity, chromosomal translocations, or epigenetic silencing is frequently observed in human malignant cancer cells. Acquisition of chemoresistance in squamous cell carcinoma, osteosarcoma, and breast cancer cells is associated with WWOX deficiency. WWOX protein physically interacts with many signaling molecules and exerts its regulatory effects on gene transcription and protein stability and subcellular localization to control cell survival, proliferation, differentiation, autophagy, and metabolism. In this review, we provide an overview of the recent advances in understanding the molecular mechanisms by which WWOX regulates cellular functions and stress responses. A potential scenario is that activation of WWOX by anticancer drugs is needed to overcome chemoresistance and trigger cancer cell death, suggesting that WWOX can be regarded as a prognostic marker and a candidate molecule for targeted cancer therapies. PMID:25595191

  10. Interleukin 2 activates extracellular signal-regulated protein kinase 2

    PubMed Central

    1993-01-01

    Interleukin 2 (IL-2) stimulated activation of the 42-kD extracellular signal-regulated kinase 2 (Erk2) in murine IL-3-dependent cells, expressing either high or intermediate affinity IL-2 receptors. Activation was both rapid, occurring within 5 min of IL-2 addition, and prolonged, remaining elevated for 30 min. Activation of Erk2 appeared to be necessary for IL-2 stimulation of proliferation, as deletion of a region of the cytoplasmic domain of the IL-2 receptor beta chain, essential for IL-2 stimulation of proliferation, abolished Erk2 activation by IL-2. Furthermore, cells that had been deprived of cytokine for 24 h were then refractory to IL-2 stimulation of both Erk2 activity and proliferation. However, elevation of Erk2 activity was not sufficient to stimulate proliferation, as protein kinase C activation stimulated Erk2 activity but not DNA synthesis. Also, cells exposed to IL-2 in the presence of rapamycin showed full Erk2 activation but not DNA synthesis. These data suggest that IL-2 must stimulate both Erk2 activity and a further pathway(s) to trigger cell proliferation. PMID:8376945

  11. BMP signaling and microtubule organization regulate synaptic strength

    PubMed Central

    Ball, Robin W.; Peled, Einat; Guerrero, Giovanna; Isacoff, Ehud Y.

    2015-01-01

    The strength of synaptic transmission between a neuron and multiple postsynaptic partners can vary considerably. We have studied synaptic heterogeneity using the glutamatergic Drosophila neuromuscular junction (NMJ), which contains multiple synaptic connections of varying strength between a motor axon and muscle fiber. In larval NMJs, there is a gradient of synaptic transmission from weak proximal to strong distal boutons. We imaged synaptic transmission with the postsynaptically targeted fluorescent calcium sensor SynapCam, to investigate the molecular pathways that determine synaptic strength and set up this gradient. We discovered that mutations in the Bone Morphogenetic Protein (BMP) signaling pathway disrupt production of strong distal boutons. We find that strong connections contain unbundled microtubules in the boutons, suggesting a role for microtubule organization in transmission strength. The spastin mutation, which disorganizes microtubules, disrupted the transmission gradient, supporting this interpretation. We propose that the BMP pathway, shown previously to function in the homeostatic regulation of synaptic growth, also boosts synaptic transmission in a spatially selective manner that depends on the microtubule system. PMID:25681521

  12. Regulation of PKC mediated signaling by calcium during visceral leishmaniasis.

    PubMed

    Roy, Nivedita; Chakraborty, Supriya; Paul Chowdhury, Bidisha; Banerjee, Sayantan; Halder, Kuntal; Majumder, Saikat; Majumdar, Subrata; Sen, Parimal C

    2014-01-01

    Calcium is an ubiquitous cellular signaling molecule that controls a variety of cellular processes and is strictly maintained in the cellular compartments by the coordination of various Ca2+ pumps and channels. Two such fundamental calcium pumps are plasma membrane calcium ATPase (PMCA) and Sarco/endoplasmic reticulum calcium ATPase (SERCA) which play a pivotal role in maintaining intracellular calcium homeostasis. This intracellular Ca2+ homeostasis is often disturbed by the protozoan parasite Leishmania donovani, the causative organism of visceral leishmaniasis. In the present study we have dileneated the involvement of PMCA4 and SERCA3 during leishmaniasis. We have observed that during leishmaniasis, intracellular Ca2+ concentration was up-regulated and was further controlled by both PMCA4 and SERCA3. Inhibition of these two Ca2+-ATPases resulted in decreased parasite burden within the host macrophages due to enhanced intracellular Ca2+. Contrastingly, on the other hand, activation of PMCA4 was found to enhance the parasite burden. Our findings also highlighted the importance of Ca2+ in the modulation of cytokine balance during leishmaniasis. These results thus cumulatively suggests that these two Ca2+-ATPases play prominent roles during visceral leishmaniasis. PMID:25329062

  13. Mitotic Checkpoint Regulators Control Insulin Signaling and Metabolic Homeostasis.

    PubMed

    Choi, Eunhee; Zhang, Xiangli; Xing, Chao; Yu, Hongtao

    2016-07-28

    Insulin signaling regulates many facets of animal physiology. Its dysregulation causes diabetes and other metabolic disorders. The spindle checkpoint proteins MAD2 and BUBR1 prevent precocious chromosome segregation and suppress aneuploidy. The MAD2 inhibitory protein p31(comet) promotes checkpoint inactivation and timely chromosome segregation. Here, we show that whole-body p31(comet) knockout mice die soon after birth and have reduced hepatic glycogen. Liver-specific ablation of p31(comet) causes insulin resistance, hyperinsulinemia, glucose intolerance, and hyperglycemia and diminishes the plasma membrane localization of the insulin receptor (IR) in hepatocytes. MAD2 directly binds to IR and facilitates BUBR1-dependent recruitment of the clathrin adaptor AP2 to IR. p31(comet) blocks the MAD2-BUBR1 interaction and prevents spontaneous clathrin-mediated IR endocytosis. BUBR1 deficiency enhances insulin sensitivity in mice. BUBR1 depletion in hepatocytes or the expression of MAD2-binding-deficient IR suppresses the metabolic phenotypes of p31(comet) ablation. Our findings establish a major IR regulatory mechanism and link guardians of chromosome stability to nutrient metabolism. PMID:27374329

  14. Cyclic AMP signalling pathways in the regulation of uterine relaxation

    PubMed Central

    Yuan, Wei; López Bernal, Andrés

    2007-01-01

    Studying the mechanism(s) of uterine relaxation is important and will be helpful in the prevention of obstetric difficulties such as preterm labour, which remains a major cause of perinatal mortality and morbidity. Multiple signalling pathways regulate the balance between maintaining relative uterine quiescence during gestation, and the transition to the contractile state at the onset of parturition. Elevation of intracellular cyclic AMP promotes myometrial relaxation, and thus quiescence, via effects on multiple intracellular targets including calcium channels, potassium channels and myosin light chain kinase. A complete understanding of cAMP regulatory pathways (synthesis and hydrolysis) would assist in the development of better tocolytics to delay or inhibit preterm labour. Here we review the enzymes involved in cAMP homoeostasis (adenylyl cyclases and phosphodiesterases) and possible myometrial substrates for the cAMP dependent protein kinase. We must emphasise the need to identify novel pharmacological targets in human pregnant myometrium to achieve safe and selective uterine relaxation when this is indicated in preterm labour or other obstetric complications. PMID:17570154

  15. Peroxiredoxin 1 suppresses apoptosis via regulation of the apoptosis signal-regulating kinase 1 signaling pathway in human oral leukoplakia

    PubMed Central

    ZHANG, MIN; NIU, WENWEN; ZHANG, JIANFEI; GE, LIHUA; YANG, JING; SUN, ZHENG; TANG, XIAOFEI

    2015-01-01

    Peroxiredoxin 1 (Prx1) has a significant role in several malignant types of tumor. However, the role of Prx1 in oral leukoplakia (OLK) has remained to be elucidated. OLK is a common precancerous lesion of the oral mucosa that has a very high malignant transformation rate. The aim of the present study was to investigate the roles of Prx1, and its association with apoptosis signal-regulating kinase 1 (ASK1) and p38 in OLK. A total of 20 OLK samples and 10 normal oral mucosa samples were obtained from patients at the Beijing Stomatological Hospital (Beijing, China). The messenger RNA (mRNA) and protein expression levels of Prx1, ASK1 and p38 were determined by polymerase chain reaction and western blot analysis, respectively. Flow cytometry was used to detect cell apoptosis. The interaction between Prx1 and ASK1 was examined in H2O2-treated DOK cells by glutathione-S-transferase pull-down assays and by co-immunoprecipitation in vitro. Compared with those of the normal oral mucosa, the mRNA levels of Prx1, ASK1 and p38 were elevated in OLK tissues (P<0.05). The protein expression levels of Prx1, phosphorylated-ASK1 (p-ASK1) and p-p38 were also significantly enhanced in OLK tissues compared with those of the normal mucosa (P<0.05). In Prx1-knockdown DOK cells, ASK1 and p38 were activated, leading to enhanced levels of apoptosis in response to H2O2. No clear interaction between Prx1 and ASK1 was detected in H2O2-treated DOK cells. Prx1 was suggested to be involved in OLK pathogenesis by providing resistance against extracellular damages from oxidative stress via inhibition of the ASK1-induced apoptotic signaling pathway. Targeting Prx1 may provide a novel therapeutic strategy for the treatment of patients with OLK. PMID:26622762

  16. Effective Self-Regulated Science Learning through Multimedia-Enriched Skeleton Concept Maps

    ERIC Educational Resources Information Center

    Maree, Ton J.; van Bruggen, Jan M.; Jochems, Wim M. G.

    2013-01-01

    Background: This study combines work on concept mapping with scripted collaborative learning. Purpose: The objective was to examine the effects of self-regulated science learning through scripting students' argumentative interactions during collaborative "multimedia-enriched skeleton concept mapping" on meaningful science learning and retention.…

  17. Quantifying time-varying coordination of multimodal speech signals using correlation map analysis.

    PubMed

    Barbosa, Adriano Vilela; Déchaine, Rose-Marie; Vatikiotis-Bateson, Eric; Yehia, Hani Camille

    2012-03-01

    This paper demonstrates an algorithm for computing the instantaneous correlation coefficient between two signals. The algorithm is the computational engine for analyzing the time-varying coordination between signals, which is called correlation map analysis (CMA). Correlation is computed around any pair of points in the two input signals. Thus, coordination can be assessed across a continuous range of temporal offsets and be detected even when changing over time due to temporal fluctuations. The correlation algorithm has two major features: (i) it is structurally similar to a tunable filter, requiring only one parameter to set its cutoff frequency (and sensitivity), (ii) it can be applied either uni-directionally (computing correlation based only on previous samples) or bi-directionally (computing correlation based on both previous and future samples). Computing instantaneous correlation for a range of time offsets between two signals produces a 2D correlation map, in which correlation is characterized as a function of time and temporal offset. Graphic visualization of the correlation map provides rapid assessment of how correspondence patterns progress through time. The utility of the algorithm and of CMA are exemplified using the spatial and temporal coordination of various audible and visible components associated with linguistic performance. PMID:22423712

  18. The MAP kinase substrate MKS1 is a regulator of plant defense responses.

    PubMed

    Andreasson, Erik; Jenkins, Thomas; Brodersen, Peter; Thorgrimsen, Stephan; Petersen, Nikolaj H T; Zhu, Shijiang; Qiu, Jin-Long; Micheelsen, Pernille; Rocher, Anne; Petersen, Morten; Newman, Mari-Anne; Bjørn Nielsen, Henrik; Hirt, Heribert; Somssich, Imre; Mattsson, Ole; Mundy, John

    2005-07-20

    Arabidopsis MAP kinase 4 (MPK4) functions as a regulator of pathogen defense responses, because it is required for both repression of salicylic acid (SA)-dependent resistance and for activation of jasmonate (JA)-dependent defense gene expression. To understand MPK4 signaling mechanisms, we used yeast two-hybrid screening to identify the MPK4 substrate MKS1. Analyses of transgenic plants and genome-wide transcript profiling indicated that MKS1 is required for full SA-dependent resistance in mpk4 mutants, and that overexpression of MKS1 in wild-type plants is sufficient to activate SA-dependent resistance, but does not interfere with induction of a defense gene by JA. Further yeast two-hybrid screening revealed that MKS1 interacts with the WRKY transcription factors WRKY25 and WRKY33. WRKY25 and WRKY33 were shown to be in vitro substrates of MPK4, and a wrky33 knockout mutant was found to exhibit increased expression of the SA-related defense gene PR1. MKS1 may therefore contribute to MPK4-regulated defense activation by coupling the kinase to specific WRKY transcription factors.

  19. The Potential for Signal Integration and Processing in Interacting Map Kinase Cascades

    PubMed Central

    Schwacke, John H.; Voit, Eberhard O.

    2009-01-01

    The cellular response to environmental stimuli requires biochemical information processing through which sensory inputs and cellular status are integrated and translated into appropriate responses by way of interacting networks of enzymes. One such network, the Mitogen Activated Protein (MAP) kinase cascade is a highly conserved signal transduction module that propagates signals from cell surface receptors to various cytosolic and nuclear targets by way of a phosphorylation cascade. We have investigated the potential for signal processing within a network of interacting feed-forward kinase cascades typified by the MAP kinase cascade. A genetic algorithm was used to search for sets of kinetic parameters demonstrating representative key input-output patterns of interest. We discuss two of the networks identified in our study, one implementing the exclusive-or function (XOR) and another implementing what we refer to as an in-band detector (IBD) or two-sided threshold. These examples confirm the potential for logic and amplitude-dependent signal processing in interacting MAP kinase cascades demonstrating limited cross-talk. Specifically, the XOR function allows the network to respond to either one, but not both signals simultaneously, while the IBD permits the network to respond exclusively to signals within a given range of strength, and to suppress signals below as well as above this range. The solution to the XOR problem is interesting in that it requires only two interacting pathways, crosstalk at only one layer, and no feedback or explicit inhibition. These types of responses are not only biologically relevant but constitute signal processing modules that can be combined to create other logical functions and that, in contrast to amplification, cannot be achieved with a single cascade or with two non-interacting cascades. Our computational results revealed surprising similarities between experimental data describing the JNK/MKK4/MKK7 pathway and the solution for

  20. The chemistry of social regulation: multicomponent signals in ant societies.

    PubMed

    Hölldobler, B

    1995-01-01

    Chemical signals mediating communication in ant societies are usually complex mixtures of substances with considerable variation in molecular composition and in relative proportions of components. Such multicomponent signals can be produced in single exocrine glands, but they can also be composed with secretions from several glands. This variation is often functional, identifying groups or specific actions on a variety of organizational levels. Chemical signals can be further combined with cues from other sensory modalities, such as vibrational or tactile stimuli. These kinds of accessory signals usually serve in modulatory communication, lowering the response threshold in the recipient for the actual releasing stimulus. Comparative studies suggest that modulatory signals evolved through ritualization from actions originally not related to the same behavioral context, and modulatory signals may further evolve to become independent releasing signals.

  1. Evaluation of Waveform Mapping as a Signal Processing Tool for Quantitative Ultrasonic NDE

    NASA Technical Reports Server (NTRS)

    Johnston, Patrick H.; Kishoni, Doron

    1993-01-01

    The mapping of one pulsed waveform into another, more desirable waveform by the application of a time-domain filter has been employed in a number of NDE situations. The primary goal of these applications has been to improve the range resolution of an ultrasonic signal for detection of echoes arising from particular interfaces masked by the response of the transducer. The work presented here addresses the use of this technique for resolution enhancement in imaging situations and in mapping signals from different transducers to a common target waveform, allowing maintenance of quantitative calibration of ultrasonic systems. We also describe the use of this technique in terms of the frequency analysis of the resulting waveforms.

  2. Regulation of protease-activated receptor 1 signaling by the adaptor protein complex 2 and R4 subfamily of regulator of G protein signaling proteins.

    PubMed

    Chen, Buxin; Siderovski, David P; Neubig, Richard R; Lawson, Mark A; Trejo, Joann

    2014-01-17

    The G protein-coupled protease-activated receptor 1 (PAR1) is irreversibly proteolytically activated by thrombin. Hence, the precise regulation of PAR1 signaling is important for proper cellular responses. In addition to desensitization, internalization and lysosomal sorting of activated PAR1 are critical for the termination of signaling. Unlike most G protein-coupled receptors, PAR1 internalization is mediated by the clathrin adaptor protein complex 2 (AP-2) and epsin-1, rather than β-arrestins. However, the function of AP-2 and epsin-1 in the regulation of PAR1 signaling is not known. Here, we report that AP-2, and not epsin-1, regulates activated PAR1-stimulated phosphoinositide hydrolysis via two different mechanisms that involve, in part, a subset of R4 subfamily of "regulator of G protein signaling" (RGS) proteins. A significantly greater increase in activated PAR1 signaling was observed in cells depleted of AP-2 using siRNA or in cells expressing a PAR1 (420)AKKAA(424) mutant with defective AP-2 binding. This effect was attributed to AP-2 modulation of PAR1 surface expression and efficiency of G protein coupling. We further found that ectopic expression of R4 subfamily members RGS2, RGS3, RGS4, and RGS5 reduced activated PAR1 wild-type signaling, whereas signaling by the PAR1 AKKAA mutant was minimally affected. Intriguingly, siRNA-mediated depletion analysis revealed a function for RGS5 in the regulation of signaling by the PAR1 wild type but not the AKKAA mutant. Moreover, activation of the PAR1 wild type, and not the AKKAA mutant, induced Gαq association with RGS3 via an AP-2-dependent mechanism. Thus, AP-2 regulates activated PAR1 signaling by altering receptor surface expression and through recruitment of RGS proteins. PMID:24297163

  3. Motion compensation of optical mapping signals from isolated beating rat hearts

    NASA Astrophysics Data System (ADS)

    Stender, B.; Ernst, F.; Wang, B.; Zhang, Z. X.; Schlaefer, A.

    2013-09-01

    Optical mapping is a well established technique for recording monophasic action potential traces on the epicardial surface of isolated hearts. This measuring technique offers a high spatial resolution but it is sensitive towards myocardial motion. Motion artifacts occur because the mapping between a certain tissue portion sending out fluorescent light and a pixel of the photo detector changes over time. So far this problem has been addressed by suppressing the motion or ratiometric imaging. We developed a different approach to compensate the motion artifacts based on image registration. We could demonstrate how an image deformation field temporally changing with the heart motion could be determined. Using these deformation field time series for image transformation motion signals could be generated for each image pixel which were then successfully applied to remove baseline shift and compensate motion artifacts potentially leading to errors within maps of the first arrival time. The investigation was based on five different rat hearts stained with Di-4-ANEPPS.

  4. Induction of p27Kip1 degradation and anchorage independence by Ras through the MAP kinase signaling pathway.

    PubMed

    Kawada, M; Yamagoe, S; Murakami, Y; Suzuki, K; Mizuno, S; Uehara, Y

    1997-08-01

    While most untransformed cells require substrate attachment for growth (anchorage dependence), the oncogenic transformed cells lack this requirement (anchorage independence) and are often tumorigenic. However, the mechanism of loss of anchorage dependence is not fully understood. When rat normal fibroblasts were cultured in suspension without substrate attachment, the cell cycle arrested in G1 phase and the cyclin-dependent kinase inhibitor p27Kip1 protein and its mRNA accumulated. Conditional expression of oncogenic Ras induced the G1-S transition of the cell cycle and significantly shortened the half-life of p27Kip1 protein without altering its mRNA level. Inhibition of the activation of mitogen-activated protein (MAP) kinase by cyclic AMP-elevating agents and a MEK inhibitor prevented the oncogenic Ras-induced degradation of p27Kip1. These results suggest that the loss of substrate attachment induces the cell cycle arrest through the up-regulation of p27Kip1 mRNA, but the oncogenic Ras confers anchorage independence by accelerating p27Kip1 degradation through the activation of the MAP kinase signaling pathway. Furthermore, we have found that p27Kip1 is phosphorylated by MAP kinase in vitro and the phosphorylated p27Kip1 cannot bind to and inhibit cdk2.

  5. Application of Polynomial and Radial Basis Function Maps to Signal Masking

    SciTech Connect

    Damiano, B.

    1998-01-01

    The objective of this research was to develop and demonstrate a technique for encrypting information by using a masking signal that closely approximates local ambient noise. Signal masking techniques developed to date have used nonlinear differential equations, spread spectrum, and various modulation schemes to encode information. While these techniques can effectively hide a signal, the resulting masks may not appear as ambient noise to an observer. The advantage of the proposed technique over commonly used masking methods is that the transmitted signal will appear as normal background noise, thus greatly reducing the probability of detection and exploitation. A promising near-term application of this technology presents itself in the area of clandestine minefield reconnaissance in shallow water areas. Shallow water mine-counter-mine (SWMCM) activity is essential for minefield avoidance, efficient minefield clearance, and effective selection of transit lanes within minefields. A key technology area for SWMCM is the development of special sonar waveforms with low probability of exploitation/intercept (LPE/LPI) attributes. In addition to LPE/LPI sonar, this technology has the potential to enable significant improvements in underwater acoustic communications. For SWMCM, the chaotic waveform research provides a mechanism for encrypted communications between a submarine (SSN) and an unmanned underwater vehicle (UUV) via an acoustic channel. Acoustic SSN/UUV communications would eliminate the need for a fiberoptic link between the two vessels, thus increasing the robustness of SWMCM. Similar applications may exist in the areas of radar masking and secure communications. The original approach called for the use of polynomial maps to generate a masking signal. Because polynomial maps were found to have highly restrictive stability criteria, the approach was modified to use radial basis function (RBF) maps. they have shown that stable RBF maps that closely approximate an

  6. High-Performance Signal Detection for Adverse Drug Events using MapReduce Paradigm.

    PubMed

    Fan, Kai; Sun, Xingzhi; Tao, Ying; Xu, Linhao; Wang, Chen; Mao, Xianling; Peng, Bo; Pan, Yue

    2010-01-01

    Post-marketing pharmacovigilance is important for public health, as many Adverse Drug Events (ADEs) are unknown when those drugs were approved for marketing. However, due to the large number of reported drugs and drug combinations, detecting ADE signals by mining these reports is becoming a challenging task in terms of computational complexity. Recently, a parallel programming model, MapReduce has been introduced by Google to support large-scale data intensive applications. In this study, we proposed a MapReduce-based algorithm, for common ADE detection approach, Proportional Reporting Ratio (PRR), and tested it in mining spontaneous ADE reports from FDA. The purpose is to investigate the possibility of using MapReduce principle to speed up biomedical data mining tasks using this pharmacovigilance case as one specific example. The results demonstrated that MapReduce programming model could improve the performance of common signal detection algorithm for pharmacovigilance in a distributed computation environment at approximately liner speedup rates. PMID:21347109

  7. Controlling False Discovery Rate in Signal Space for Transformation-Invariant Thresholding of Statistical Maps.

    PubMed

    Li, Junning; Shi, Yonggang; Toga, Arthur W

    2015-01-01

    Thresholding statistical maps with appropriate correction of multiple testing remains a critical and challenging problem in brain mapping. Since the false discovery rate (FDR) criterion was introduced to the neuroimaging community a decade ago, various improvements have been proposed. However, a highly desirable feature, transformation invariance, has not been adequately addressed, especially for voxel-based FDR. Thresholding applied after spatial transformation is not necessarily equivalent to transformation applied after thresholding in the original space. We find this problem closely related to another important issue: spatial correlation of signals. A Gaussian random vector-valued image after normalization is a random map from a Euclidean space to a high-dimension unit-sphere. Instead of defining the FDR measure in the image's Euclidean space, we define it in the signals' hyper-spherical space whose measure not only reflects the intrinsic "volume" of signals' randomness but also keeps invariant under images' spatial transformation. Experiments with synthetic and real images demonstrate that our method achieves transformation invariance and significantly minimizes the bias introduced by the choice of template images.

  8. Plant elicitor peptides are conserved signals regulating direct and indirect anti-herbivore defense

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insect-induced defenses occur in nearly all plants and are regulated by conserved signaling pathways. As the first described plant peptide signal, systemin regulates anti-herbivore defenses in the Solanaceae, but in other plant families peptides with analogous activity have remained elusive. In the ...

  9. Plant elicitor peptides are conserved signals regulating direct and indirect anti-herbivore defense

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Insect-induced defenses occur in nearly all plants and are regulated by conserved signaling pathways. As the first described plant peptide signal, systemin regulates anti-herbivore defenses in the Solanaceae, but in other plant families peptides with analogous activity have remained elusive. In th...

  10. Regulation of Protease-activated Receptor 1 Signaling by the Adaptor Protein Complex 2 and R4 Subfamily of Regulator of G Protein Signaling Proteins*

    PubMed Central

    Chen, Buxin; Siderovski, David P.; Neubig, Richard R.; Lawson, Mark A.; Trejo, JoAnn

    2014-01-01

    The G protein-coupled protease-activated receptor 1 (PAR1) is irreversibly proteolytically activated by thrombin. Hence, the precise regulation of PAR1 signaling is important for proper cellular responses. In addition to desensitization, internalization and lysosomal sorting of activated PAR1 are critical for the termination of signaling. Unlike most G protein-coupled receptors, PAR1 internalization is mediated by the clathrin adaptor protein complex 2 (AP-2) and epsin-1, rather than β-arrestins. However, the function of AP-2 and epsin-1 in the regulation of PAR1 signaling is not known. Here, we report that AP-2, and not epsin-1, regulates activated PAR1-stimulated phosphoinositide hydrolysis via two different mechanisms that involve, in part, a subset of R4 subfamily of “regulator of G protein signaling” (RGS) proteins. A significantly greater increase in activated PAR1 signaling was observed in cells depleted of AP-2 using siRNA or in cells expressing a PAR1 420AKKAA424 mutant with defective AP-2 binding. This effect was attributed to AP-2 modulation of PAR1 surface expression and efficiency of G protein coupling. We further found that ectopic expression of R4 subfamily members RGS2, RGS3, RGS4, and RGS5 reduced activated PAR1 wild-type signaling, whereas signaling by the PAR1 AKKAA mutant was minimally affected. Intriguingly, siRNA-mediated depletion analysis revealed a function for RGS5 in the regulation of signaling by the PAR1 wild type but not the AKKAA mutant. Moreover, activation of the PAR1 wild type, and not the AKKAA mutant, induced Gαq association with RGS3 via an AP-2-dependent mechanism. Thus, AP-2 regulates activated PAR1 signaling by altering receptor surface expression and through recruitment of RGS proteins. PMID:24297163

  11. A quantitative analysis of signal reproduction from cylinder recordings measured via noncontact full surface mapping.

    PubMed

    Nascè, Antony; Hill, Martyn; McBride, John W; Boltryk, Peter J

    2008-10-01

    Sound reproduction via a noncontact surface mapping technique has great potential for sound archives, aiming to digitize content from early sound recordings such as wax cylinders, which may otherwise be "unplayable" with a stylus. If the noncontact techniques are to be considered a viable solution for sound archivists, a method for quantifying the quality of the reproduced signal needs to be developed. In this study, a specially produced test cylinder recording, encoded with sinusoids, provides the basis for the first quantitative analysis of signal reproduction from the noncontact full surface mapping method. The sampling and resolution of the measurement system are considered with respect to the requirements for digital archiving of cylinder recordings. Two different methods of audio signal estimation from a discrete groove cross section are described and rated in terms of signal-to-noise ratio and total harmonic distortion. Noncontact and stylus methods of sound reproduction are then compared using the same test cylinder. It is shown that noncontact methods appear to have distinct advantages over stylus reproduction, in terms of reduced harmonic distortion and lower frequency modulation. PMID:19062844

  12. A scalable neuroinformatics data flow for electrophysiological signals using MapReduce

    PubMed Central

    Jayapandian, Catherine; Wei, Annan; Ramesh, Priya; Zonjy, Bilal; Lhatoo, Samden D.; Loparo, Kenneth; Zhang, Guo-Qiang; Sahoo, Satya S.

    2015-01-01

    Data-driven neuroscience research is providing new insights in progression of neurological disorders and supporting the development of improved treatment approaches. However, the volume, velocity, and variety of neuroscience data generated from sophisticated recording instruments and acquisition methods have exacerbated the limited scalability of existing neuroinformatics tools. This makes it difficult for neuroscience researchers to effectively leverage the growing multi-modal neuroscience data to advance research in serious neurological disorders, such as epilepsy. We describe the development of the Cloudwave data flow that uses new data partitioning techniques to store and analyze electrophysiological signal in distributed computing infrastructure. The Cloudwave data flow uses MapReduce parallel programming algorithm to implement an integrated signal data processing pipeline that scales with large volume of data generated at high velocity. Using an epilepsy domain ontology together with an epilepsy focused extensible data representation format called Cloudwave Signal Format (CSF), the data flow addresses the challenge of data heterogeneity and is interoperable with existing neuroinformatics data representation formats, such as HDF5. The scalability of the Cloudwave data flow is evaluated using a 30-node cluster installed with the open source Hadoop software stack. The results demonstrate that the Cloudwave data flow can process increasing volume of signal data by leveraging Hadoop Data Nodes to reduce the total data processing time. The Cloudwave data flow is a template for developing highly scalable neuroscience data processing pipelines using MapReduce algorithms to support a variety of user applications. PMID:25852536

  13. A scalable neuroinformatics data flow for electrophysiological signals using MapReduce.

    PubMed

    Jayapandian, Catherine; Wei, Annan; Ramesh, Priya; Zonjy, Bilal; Lhatoo, Samden D; Loparo, Kenneth; Zhang, Guo-Qiang; Sahoo, Satya S

    2015-01-01

    Data-driven neuroscience research is providing new insights in progression of neurological disorders and supporting the development of improved treatment approaches. However, the volume, velocity, and variety of neuroscience data generated from sophisticated recording instruments and acquisition methods have exacerbated the limited scalability of existing neuroinformatics tools. This makes it difficult for neuroscience researchers to effectively leverage the growing multi-modal neuroscience data to advance research in serious neurological disorders, such as epilepsy. We describe the development of the Cloudwave data flow that uses new data partitioning techniques to store and analyze electrophysiological signal in distributed computing infrastructure. The Cloudwave data flow uses MapReduce parallel programming algorithm to implement an integrated signal data processing pipeline that scales with large volume of data generated at high velocity. Using an epilepsy domain ontology together with an epilepsy focused extensible data representation format called Cloudwave Signal Format (CSF), the data flow addresses the challenge of data heterogeneity and is interoperable with existing neuroinformatics data representation formats, such as HDF5. The scalability of the Cloudwave data flow is evaluated using a 30-node cluster installed with the open source Hadoop software stack. The results demonstrate that the Cloudwave data flow can process increasing volume of signal data by leveraging Hadoop Data Nodes to reduce the total data processing time. The Cloudwave data flow is a template for developing highly scalable neuroscience data processing pipelines using MapReduce algorithms to support a variety of user applications. PMID:25852536

  14. The TOR signaling pathway regulates vegetative development and virulence in Fusarium graminearum.

    PubMed

    Yu, Fangwei; Gu, Qin; Yun, Yingzi; Yin, Yanni; Xu, Jin-Rong; Shim, Won-Bo; Ma, Zhonghua

    2014-07-01

    The target of rapamycin (TOR) signaling pathway plays critical roles in controlling cell growth in a variety of eukaryotes. However, the contribution of this pathway in regulating virulence of plant pathogenic fungi is unknown. We identified and characterized nine genes encoding components of the TOR pathway in Fusarium graminearum. Biological, genetic and biochemical functions of each component were investigated. The FgFkbp12-rapamycin complex binds to the FgTor kinase. The type 2A phosphatases FgPp2A, FgSit4 and FgPpg1 were found to interact with FgTap42, a downstream component of FgTor. Among these, we determined that FgPp2A is likely to be essential for F. graminearum survival, and FgSit4 and FgPpg1 play important roles in cell wall integrity by positively regulating the phosphorylation of FgMgv1, a key MAP kinase in the cell wall integrity pathway. In addition, the FgPpg1 interacting protein, FgTip41, is involved in regulating mycelial growth and virulence. Notably, FgTip41 does not interact with FgTap42 but with FgPpg1, suggesting the existence of FgTap42:FgPpg1:FgTip41 heterotrimer in F. graminearum, a complex not observed in the yeast model. Collectively, we defined a genetic regulatory framework that elucidates how the TOR pathway regulates virulence and vegetative development in F. graminearum.

  15. Nf1 regulates hematopoietic progenitor cell growth and ras signaling in response to multiple cytokines.

    PubMed

    Zhang, Y Y; Vik, T A; Ryder, J W; Srour, E F; Jacks, T; Shannon, K; Clapp, D W

    1998-06-01

    Neurofibromin, the protein encoded by the NF1 tumor-suppressor gene, negatively regulates the output of p21(ras) (Ras) proteins by accelerating the hydrolysis of active Ras-guanosine triphosphate to inactive Ras-guanosine diphosphate. Children with neurofibromatosis type 1 (NF1) are predisposed to juvenile chronic myelogenous leukemia (JCML) and other malignant myeloid disorders, and heterozygous Nf1 knockout mice spontaneously develop a myeloid disorder that resembles JCML. Both human and murine leukemias show loss of the normal allele. JCML cells and Nf1-/- hematopoietic cells isolated from fetal livers selectively form abnormally high numbers of colonies derived from granulocyte-macrophage progenitors in cultures supplemented with low concentrations of granulocyte-macrophage colony stimulating factor (GM-CSF). Taken together, these data suggest that neurofibromin is required to downregulate Ras activation in myeloid cells exposed to GM-CSF. We have investigated the growth and proliferation of purified populations of hematopoietic progenitor cells isolated from Nf1 knockout mice in response to the cytokines interleukin (IL)-3 and stem cell factor (SCF), as well as to GM-CSF. We found abnormal proliferation of both immature and lineage-restricted progenitor populations, and we observed increased synergy between SCF and either IL-3 or GM-CSF in Nf1-/- progenitors. Nf1-/- fetal livers also showed an absolute increase in the numbers of immature progenitors. We further demonstrate constitutive activation of the Ras-Raf-MAP (mitogen-activated protein) kinase signaling pathway in primary c-kit+ Nf1-/- progenitors and hyperactivation of MAP kinase after growth factor stimulation. The results of these experiments in primary hematopoietic cells implicate Nf1 as playing a central role in regulating the proliferation and survival of primitive and lineage-restricted myeloid progenitors in response to multiple cytokines by modulating Ras output.

  16. An application of mapping neural networks and a digital signal processor for cochlear neuroprostheses.

    PubMed

    Zadák, J; Unbehauen, R

    1993-01-01

    Cochlear neuroprostheses strive to restore the sensation of hearing to patients with a profound sensorineural deafness. They exhibit a stimulation of the surviving auditory nerve neurons by electrical currents delivered through electrodes placed on or within the cochlea. The present article describes a new method for an efficient derivation of the required information from the incoming speech signal necessary for the implant stimulation. Also some realization aspects of the new approach are addressed. In the new strategy, a multilayer neural network is employed in the formant frequency estimation having some suitable speech signal descriptors as particular input signals. The proposed method allows us a fast formant frequency estimation necessary for the implant stimulation. With the developed strategy, the prosthesis can be adjusted to the environment which the patient is supposed to live in. Moreover, the neural network concept offers us an alternative for dealing with the areas of neural loss or "holes" in the frequency map of the patient's ear.

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

    PubMed Central

    Poddar, Ranjana; Paul, Surojit

    2009-01-01

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

  18. Regulation by gravity of the transcript levels of MAP65 in azuki bean epicotyls

    NASA Astrophysics Data System (ADS)

    Soga, Kouichi; Hoson, Takayuki; Wakabayashi, Kazuyuki; Kotake, Toshihisa

    2012-07-01

    Development of a short and thick body by reorientation of cortical microtubules is required for the resistance of plants to the gravitational force. The 65 kDa microtubule-associated protein (MAP65) has microtubule bundling activity and is involved in the reorientation of cortical microtubules. Here, we investigated the relation between the orientation of cortical microtubules and the transcript levels of VaMAP65-1 under centrifugal hypergravity conditions in azuki bean epicotyls. The percentage of cells with transverse microtubules was decreased, while that with longitudinal microtubules was increased, in proportion to the logarithm of the magnitude of gravity. The orientation of microtubules was restored to the original direction after removal of the hypergravity stimulus. The transcript level of VaMAP65-1 was down-regulated in proportion to the logarithm of the magnitude of gravity (R=-0.99). By removal of hypergravity stimulus, expression of VaMAP65-1 was increased to control levels. Strong correlations were observed between the percentage of cells with longitudinal or transverse microtubules and the transcript levels of VaMAP65-1 (R=-0.93, 0.91). These results suggest that down-regulation of VaMAP65-1 expression is involved in the regulation by gravity of the orientation of cortical microtubules in azuki bean epicotyls. Lanthanum and gadolinium ions, potential blockers of mechanosensitive calcium ion-permeable channels (mechanoreceptors), nullified the down-regulation of expression of VaMAP65-1 gene, suggesting that mechanoreceptors are responsible for regulation by gravity of VaMAP65-1 expression.

  19. Vascular endothelial growth factor signaling regulates the segregation of artery and vein via ERK activity during vascular development

    SciTech Connect

    Kim, Se-Hee; Schmitt, Christopher E.; Woolls, Melissa J.; Holland, Melinda B.; Kim, Jun-Dae; Jin, Suk-Won

    2013-01-25

    Highlights: ► VEGF-A signaling regulates the segregation of axial vessels. ► VEGF-A signaling is mediated by PKC and ERK in this process. ► Ectopic activation of ERK is sufficient to rescue defects in vessel segregation. -- Abstract: Segregation of two axial vessels, the dorsal aorta and caudal vein, is one of the earliest patterning events occur during development of vasculature. Despite the importance of this process and recent advances in our understanding on vascular patterning during development, molecular mechanisms that coordinate the segregation of axial vessels remain largely elusive. In this report, we find that vascular endothelial growth factor-A (Vegf-A) signaling regulates the segregation of dorsal aorta and axial vein during development. Inhibition of Vegf-A pathway components including ligand Vegf-A and its cognate receptor Kdrl, caused failure in segregation of axial vessels in zebrafish embryos. Similarly, chemical inhibition of Mitogen-activated protein kinase kinase (Map2k1)/Extracellular-signal-regulated kinases (Erk) and phosphatidylinositol 3-kinases (PI3 K), which are downstream effectors of Vegf-A signaling pathway, led to the fusion of two axial vessels. Moreover, we find that restoring Erk activity by over-expression of constitutively active MEK in embryos with a reduced level of Vegf-A signaling can rescue the defects in axial vessel segregation. Taken together, our data show that segregation of axial vessels requires the function of Vegf-A signaling, and Erk may function as the major downstream effector in this process.

  20. Ethanol Negatively Regulates Hepatic Differentiation of hESC by Inhibition of the MAPK/ERK Signaling Pathway In Vitro

    PubMed Central

    Ma, Xiaocui; Tschudy-Seney, Benjamin; Chen, Jiamei; Magner, Nataly L.; Revzin, Alexander; Nolta, Jan A.; Zern, Mark A.; Duan, Yuyou

    2014-01-01

    Background Alcohol insult triggers complex events in the liver, promoting fibrogenic/inflammatory signals and in more advanced cases, aberrant matrix deposition. It is well accepted that the regenerative capacity of the adult liver is impaired during alcohol injury. The liver progenitor/stem cells have been shown to play an important role in liver regeneration -in response to various chronic injuries; however, the effects of alcohol on stem cell differentiation in the liver are not well understood. Methods We employed hepatic progenitor cells derived from hESCs to study the impact of ethanol on hepatocyte differentiation by exposure of these progenitor cells to ethanol during hepatocyte differentiation. Results We found that ethanol negatively regulated hepatic differentiation of hESC-derived hepatic progenitor cells in a dose-dependent manner. There was also a moderate cell cycle arrest at G1/S checkpoint in the ethanol treated cells, which is associated with a reduced level of cyclin D1 in these cells. Ethanol treatment specifically inhibited the activation of the ERK but not JNK nor the p38 MAP signaling pathway. At the same time, the WNT signaling pathway was also reduced in the cells exposed to ethanol. Upon evaluating the effects of the inhibitors of these two signaling pathways, we determined that the Erk inhibitor replicated the effects of ethanol on the hepatocyte differentiation and attenuated the WNT/β-catenin signaling, however, inhibitors of WNT only partially replicated the effects of ethanol on the hepatocyte differentiation. Conclusion Our results demonstrated that ethanol negatively regulated hepatic differentiation of hESC-derived hepatic progenitors through inhibiting the MAPK/ERK signaling pathway, and subsequently attenuating the WNT signaling pathway. Thus, our finding provides a novel insight into the mechanism by which alcohol regulates cell fate selection of hESC-derived hepatic progenitor cells, and the identified pathways may provide

  1. Does Concept-Mapping Strategy Work for Everyone? The Levels of Generativity and Learners' Self-Regulated Learning Skills

    ERIC Educational Resources Information Center

    Lim, Kyu Yon; Lee, Hyeon Woo; Grabowski, Barbara

    2009-01-01

    The purpose of this study was to examine the effect of concept-mapping strategies with three different generativity levels (expert-generated concept map, partially learner-generated concept map, fully learner-generated concept map) on knowledge acquisition. Interaction between learners' self-regulated learning (SRL) skills and different levels of…

  2. Mutations in MAP3K7 that Alter the Activity of the TAK1 Signaling Complex Cause Frontometaphyseal Dysplasia.

    PubMed

    Wade, Emma M; Daniel, Philip B; Jenkins, Zandra A; McInerney-Leo, Aideen; Leo, Paul; Morgan, Tim; Addor, Marie Claude; Adès, Lesley C; Bertola, Debora; Bohring, Axel; Carter, Erin; Cho, Tae-Joon; Duba, Hans-Christoph; Fletcher, Elaine; Kim, Chong A; Krakow, Deborah; Morava, Eva; Neuhann, Teresa; Superti-Furga, Andrea; Veenstra-Knol, Irma; Wieczorek, Dagmar; Wilson, Louise C; Hennekam, Raoul C M; Sutherland-Smith, Andrew J; Strom, Tim M; Wilkie, Andrew O M; Brown, Matthew A; Duncan, Emma L; Markie, David M; Robertson, Stephen P

    2016-08-01

    Frontometaphyseal dysplasia (FMD) is a progressive sclerosing skeletal dysplasia affecting the long bones and skull. The cause of FMD in some individuals is gain-of-function mutations in FLNA, although how these mutations result in a hyperostotic phenotype remains unknown. Approximately one half of individuals with FMD have no identified mutation in FLNA and are phenotypically very similar to individuals with FLNA mutations, except for an increased tendency to form keloid scars. Using whole-exome sequencing and targeted Sanger sequencing in 19 FMD-affected individuals with no identifiable FLNA mutation, we identified mutations in two genes-MAP3K7, encoding transforming growth factor β (TGF-β)-activated kinase (TAK1), and TAB2, encoding TAK1-associated binding protein 2 (TAB2). Four mutations were found in MAP3K7, including one highly recurrent (n = 15) de novo mutation (c.1454C>T [ p.Pro485Leu]) proximal to the coiled-coil domain of TAK1 and three missense mutations affecting the kinase domain (c.208G>C [p.Glu70Gln], c.299T>A [p.Val100Glu], and c.502G>C [p.Gly168Arg]). Notably, the subjects with the latter three mutations had a milder FMD phenotype. An additional de novo mutation was found in TAB2 (c.1705G>A, p.Glu569Lys). The recurrent mutation does not destabilize TAK1, or impair its ability to homodimerize or bind TAB2, but it does increase TAK1 autophosphorylation and alter the activity of more than one signaling pathway regulated by the TAK1 kinase complex. These findings show that dysregulation of the TAK1 complex produces a close phenocopy of FMD caused by FLNA mutations. Furthermore, they suggest that the pathogenesis of some of the filaminopathies caused by FLNA mutations might be mediated by misregulation of signaling coordinated through the TAK1 signaling complex. PMID:27426733

  3. Cereblon negatively regulates TLR4 signaling through the attenuation of ubiquitination of TRAF6

    PubMed Central

    Min, Yoon; Wi, Sae Mi; Kang, Jung-Ah; Yang, Taewoo; Park, Chul-Seung; Park, Sung-Gyoo; Chung, Sungkwon; Shim, Jae-Hyuck; Chun, Eunyoung; Lee, Ki-Young

    2016-01-01

    Cereblon (CRBN) is a substrate receptor protein for the CRL4A E3 ubiquitin ligase complex. In this study, we report on a new regulatory role of CRBN in TLR4 signaling. CRBN overexpression leads to suppression of NF-κB activation and production of pro-inflammatory cytokines including IL-6 and IL-1β in response to TLR4 stimulation. Biochemical studies revealed interactions between CRBN and TAK1, and TRAF6 proteins. The interaction between CRBN and TAK1 did not affect the association of the TAB1 and TAB2 proteins, which have pivotal roles in the activation of TAK1, whereas the CRBN-TRAF6 interaction critically affected ubiquitination of TRAF6 and TAB2. Binding mapping results revealed that CRBN interacts with the Zinc finger domain of TRAF6, which contains the ubiquitination site of TRAF6, leading to attenuation of ubiquitination of TRAF6 and TAB2. Functional studies revealed that CRBN-knockdown THP-1 cells show enhanced NF-κB activation and p65- or p50-DNA binding activities, leading to up-regulation of NF-κB-dependent gene expression and increased pro-inflammatory cytokine levels in response to TLR4 stimulation. Furthermore, Crbn−/− mice exhibit decreased survival in response to LPS challenge, accompanied with marked enhancement of pro-inflammatory cytokines, such as TNF-α and IL-6. Taken together, our data demonstrate that CRBN negatively regulates TLR4 signaling via attenuation of TRAF6 and TAB2 ubiquitination. PMID:27468689

  4. Signals and Cells Involved in Regulating Liver Regeneration

    PubMed Central

    Kang, Liang-I.; Mars, Wendy M.; Michalopoulos, George K.

    2012-01-01

    Liver regeneration is a complex phenomenon aimed at maintaining a constant liver mass in the event of injury resulting in loss of hepatic parenchyma. Partial hepatectomy is followed by a series of events involving multiple signaling pathways controlled by mitogenic growth factors (HGF, EGF) and their receptors (MET and EGFR). In addition multiple cytokines and other signaling molecules contribute to the orchestration of a signal which drives hepatocytes into DNA synthesis. The other cell types of the liver receive and transmit to hepatocytes complex signals so that, in the end of the regenerative process, complete hepatic tissue is assembled and regeneration is terminated at the proper time and at the right liver size. If hepatocytes fail to participate in this process, the biliary compartment is mobilized to generate populations of progenitor cells which transdifferentiate into hepatocytes and restore liver size. PMID:24710554

  5. Regulation of the feedback antagonist naked cuticle by Wingless signaling

    PubMed Central

    Chang, Jinhee L.; Chang, Mikyung V.; Barolo, Scott; Cadigan, Ken M.

    2008-01-01

    Signaling pathways usually activate transcriptional targets in a cell type-specific manner. Notable exceptions are pathway-specific feedback antagonists, which serve to restrict the range or duration of the signal. These factors are often activated by their respective pathways in a broad array of cell types. For example, the Wnt ligand Wingless (Wg) activates the naked cuticle (nkd) gene in all tissues examined throughout Drosophila development. How does the nkd gene respond in such an unrestricted manner to Wg signaling? Analysis in cell culture revealed regions of the nkd locus that contain Wg response elements (WREs) that are directly activated by the pathway via the transcription factor TCF. In flies, Wg signaling activates these WREs in multiple tissues, in distinct but overlapping patterns. These WREs are necessary and largely sufficient for nkd expression in late stage larval tissues, but only contribute to part of the embryonic expression pattern of nkd. These results demonstrate that nkd responsiveness to Wg signaling is achieved by several WREs which are broadly (but not universally) activated by the pathway. The existence of several WREs in the nkd locus may have been necessary to allow the Wg signaling-Nkd feedback circuit to remain intact as Wg expression diversified during animal evolution. PMID:18585374

  6. Definition of an Enhanced Map-Matching Algorithm for Urban Environments with Poor GNSS Signal Quality

    PubMed Central

    Jiménez, Felipe; Monzón, Sergio; Naranjo, Jose Eugenio

    2016-01-01

    Vehicle positioning is a key factor for numerous information and assistance applications that are included in vehicles and for which satellite positioning is mainly used. However, this positioning process can result in errors and lead to measurement uncertainties. These errors come mainly from two sources: errors and simplifications of digital maps and errors in locating the vehicle. From that inaccurate data, the task of assigning the vehicle’s location to a link on the digital map at every instant is carried out by map-matching algorithms. These algorithms have been developed to fulfil that need and attempt to amend these errors to offer the user a suitable positioning. In this research; an algorithm is developed that attempts to solve the errors in positioning when the Global Navigation Satellite System (GNSS) signal reception is frequently lost. The algorithm has been tested with satisfactory results in a complex urban environment of narrow streets and tall buildings where errors and signal reception losses of the GPS receiver are frequent. PMID:26861320

  7. Definition of an Enhanced Map-Matching Algorithm for Urban Environments with Poor GNSS Signal Quality.

    PubMed

    Jiménez, Felipe; Monzón, Sergio; Naranjo, Jose Eugenio

    2016-02-04

    Vehicle positioning is a key factor for numerous information and assistance applications that are included in vehicles and for which satellite positioning is mainly used. However, this positioning process can result in errors and lead to measurement uncertainties. These errors come mainly from two sources: errors and simplifications of digital maps and errors in locating the vehicle. From that inaccurate data, the task of assigning the vehicle's location to a link on the digital map at every instant is carried out by map-matching algorithms. These algorithms have been developed to fulfil that need and attempt to amend these errors to offer the user a suitable positioning. In this research; an algorithm is developed that attempts to solve the errors in positioning when the Global Navigation Satellite System (GNSS) signal reception is frequently lost. The algorithm has been tested with satisfactory results in a complex urban environment of narrow streets and tall buildings where errors and signal reception losses of the GPS receiver are frequent.

  8. Definition of an Enhanced Map-Matching Algorithm for Urban Environments with Poor GNSS Signal Quality.

    PubMed

    Jiménez, Felipe; Monzón, Sergio; Naranjo, Jose Eugenio

    2016-01-01

    Vehicle positioning is a key factor for numerous information and assistance applications that are included in vehicles and for which satellite positioning is mainly used. However, this positioning process can result in errors and lead to measurement uncertainties. These errors come mainly from two sources: errors and simplifications of digital maps and errors in locating the vehicle. From that inaccurate data, the task of assigning the vehicle's location to a link on the digital map at every instant is carried out by map-matching algorithms. These algorithms have been developed to fulfil that need and attempt to amend these errors to offer the user a suitable positioning. In this research; an algorithm is developed that attempts to solve the errors in positioning when the Global Navigation Satellite System (GNSS) signal reception is frequently lost. The algorithm has been tested with satisfactory results in a complex urban environment of narrow streets and tall buildings where errors and signal reception losses of the GPS receiver are frequent. PMID:26861320

  9. A NPxY-independent {beta}5 integrin activation signal regulates phagocytosis of apoptotic cells

    SciTech Connect

    Singh, Sukhwinder; D'mello, Veera; Henegouwen, Paul van Bergen en; Birge, Raymond B.

    2007-12-21

    Integrin receptors are heterodimeric transmembrane receptors with critical functions in cell adhesion and migration, cell cycle progression, differentiation, apoptosis, and phagocytosis of apoptotic cells. Integrins are activated by intracellular signaling that alter the binding affinity for extracellular ligands, so-called inside to outside signaling. A common element for integrin activation involves binding of the cytoskeletal protein talin, via its FERM domain, to a highly conserved NPxY motif in the {beta} chain cytoplasmic tails, which is involved in long-range conformation changes to the extracellular domain that impinges on ligand affinity. When the human beta-5 ({beta}5) integrin cDNA was expressed in {alpha}v positive, {beta}5 and {beta}3 negative hamster CS-1 cells, it promoted NPxY-dependent adhesion to VTN-coated surfaces, phosphorylation of FAK, and concomitantly, {beta}5 integrin-EGFP protein was recruited into talin and paxillin-containing focal adhesions. Expression of a NPxY destabilizing {beta}5 mutant (Y750A) abrogated adhesion and {beta}5-Y750A-EGFP was excluded from focal adhesions at the tips of stress fibers. Surprisingly, expression of {beta}5 Y750A integrin had a potent gain-of-function effect on apoptotic cell phagocytosis, and further, a {beta}5-Y750A-EGFP fusion integrin readily bound MFG-E8-coated 10 {mu}m diameter microspheres developed as apoptotic cell mimetics. The critical sequences in {beta}5 integrin were mapped to a YEMAS motif just proximal to the NPxY motif. Our studies suggest that the phagocytic function of {beta}5 integrin is regulated by an unconventional NPxY-talin-independent activation signal and argue for the existence of molecular switches in the {beta}5 cytoplasmic tail for adhesion and phagocytosis.

  10. The Adapter Molecule Sin Regulates T-Cell-Receptor-Mediated Signal Transduction by Modulating Signaling Substrate Availability

    PubMed Central

    Xing, Luzhou; Donlin, Laura T.; Miller, Rebecca H.; Alexandropoulos, Konstantina

    2004-01-01

    Engagement of the T-cell receptor (TCR) results in the activation of a multitude of signaling events that regulate the function of T lymphocytes. These signaling events are in turn modulated by adapter molecules, which control the final functional output through the formation of multiprotein complexes. In this report, we identified the adapter molecule Sin as a new regulator of T-cell activation. We found that the expression of Sin in transgenic T lymphocytes and Jurkat T cells inhibited interleukin-2 expression and T-cell proliferation. This inhibitory effect was specific and was due to defective phospholipase C-γ (PLC-γ) phosphorylation and activation. In contrast to other adapters that become phosphorylated upon TCR stimulation, Sin was constitutively phosphorylated in resting cells by the Src kinase Fyn and bound to signaling intermediates, including PLC-γ. In stimulated cells, Sin was transiently dephosphorylated, which coincided with transient dissociation of Fyn and PLC-γ. Downregulation of Sin expression using Sin-specific short interfering RNA oligonucleotides inhibited transcriptional activation in response to TCR stimulation. Our results suggest that endogenous Sin influences T-lymphocyte signaling by sequestering signaling substrates and regulating their availability and/or activity in resting cells, while Sin is required for targeting these intermediates to the TCR for fast signal transmission during stimulation. PMID:15121874

  11. Topology mapping of insulin-regulated glucose transporter GLUT4 using computational biology.

    PubMed

    Chakraborty, Chiranjib; Bandyopadhyay, Sanghamitra; Maulik, Ujjwal; Agoramoorthy, Govindasamy

    2013-01-01

    The type 2 diabetes is increasing rapidly around the globe. The primary cause for this is insulin resistance due to the disruption of the insulin signal transduction mechanism. Insulin signal transduction stimulates glucose transport through the glucose transporter GLUT4, by promoting the exocytosis process. Understanding the structural topology of GLUT4 mechanism will increase our understanding of the dynamic activities about glucose transport and its regulation in the membrane environment. However, little is known about the topology of GLUT4. In this article, we have determined the amino acid composition, disulfide topology, structure conformation pattern of GLUT4. The amino acid composition portrays that leucine composition is the highest contributing to 15.5% among all other amino acids. Three cysteine residues such as Cys223, Cys361, and Cys363 were observed and the last two were associated with one disulfide bond formation. We have generated surface cavities to know the clefts/pockets on the surface of this protein that showed few irregular cavities placed mostly in the transmembrane-helical part. Besides, topology mapping of 12 transmembrane-helixes was done to predict N- and O-glycosylation sites and to show the highly glycosylated GLUT4 that includes both N- and O-glycosylation sites. Furthermore, hydrophobic segment and molecular charge distribution were analyzed. This article shows that bioinformatics tools can provide a rapid methodology to predict the topology of GLUT4. It also provides insights into the structural details and structural functioning relationships in the human GLUT4. The results can be of great help to advance future drug development research using GLUT4 as a target protein.

  12. SP8 regulates signaling centers during craniofacial development.

    PubMed

    Kasberg, Abigail D; Brunskill, Eric W; Steven Potter, S

    2013-09-15

    Much of the bone, cartilage and smooth muscle of the vertebrate face is derived from neural crest (NC) cells. During craniofacial development, the anterior neural ridge (ANR) and olfactory pit (OP) signaling centers are responsible for driving the outgrowth, survival, and differentiation of NC populated facial prominences, primarily via FGF. While much is known about the functional importance of signaling centers, relatively little is understood of how these signaling centers are made and maintained. In this report we describe a dramatic craniofacial malformation in mice mutant for the zinc finger transcription factor gene Sp8. At E14.5 they show facial prominences that are reduced in size and underdeveloped, giving an almost faceless phenotype. At later times they show severe midline defects, excencephaly, hyperterlorism, cleft palate, and a striking loss of many NC and paraxial mesoderm derived cranial bones. Sp8 expression was primarily restricted to the ANR and OP regions during craniofacial development. Analysis of an extensive series of conditional Sp8 mutants confirmed the critical role of Sp8 in signaling centers, and not directly in the NC and paraxial mesoderm cells. The NC cells of the Sp8 mutants showed increased levels of apoptosis and decreased cell proliferation, thereby explaining the reduced sizes of the facial prominences. Perturbed gene expression in the Sp8 mutants was examined by laser capture microdissection coupled with microarrays, as well as in situ hybridization and immunostaining. The most dramatic differences included striking reductions in Fgf8 and Fgf17 expression in the ANR and OP signaling centers. We were also able to achieve genetic and pharmaceutical partial rescue of the Sp8 mutant phenotype by reducing Sonic Hedgehog (SHH) signaling. These results show that Sp8 primarily functions to promote Fgf expression in the ANR and OP signaling centers that drive the survival, proliferation, and differentiation of the NC and paraxial

  13. SP8 regulates signaling centers during craniofacial development

    PubMed Central

    Kasberg, Abigail D.; Brunskill, Eric W.; Potter, S. Steven

    2014-01-01

    Much of the bone, cartilage and smooth muscle of the vertebrate face is derived from neural crest (NC) cells. During craniofacial development, the anterior neural ridge (ANR) and olfactory pit (OP) signaling centers are responsible for driving the outgrowth, survival, and differentiation of NC populated facial prominences, primarily via FGF. While much is known about the functional importance of signaling centers, relatively little is understood of how these signaling centers are made and maintained. In this report we describe a dramatic craniofacial malformation in mice mutant for the zinc finger transcription factor gene Sp8. At E14.5 they show facial prominences that are reduced in size and underdeveloped, giving an almost faceless phenotype. At later times they show severe midline defects, excencephaly, hyperterlorism, cleft palate, and a striking loss of many NC and paraxial mesoderm derived cranial bones. Sp8 expression was primarily restricted to the ANR and OP regions during craniofacial development. Analysis of an extensive series of conditional Sp8 mutants confirmed the critical role of Sp8 in signaling centers, and not directly in the NC and paraxial mesoderm cells. The NC cells of the Sp8 mutants showed increased levels of apoptosis and decreased cell proliferation, thereby explaining the reduced sizes of the facial prominences. Perturbed gene expression in the Sp8 mutants was examined by laser capture microdissection coupled with microarrays, as well as in situ hybridization and immunostaining. The most dramatic differences included striking reductions in Fgf8 and Fgf17 expression in the ANR and OP signaling centers. We were also able to achieve genetic and pharmaceutical partial rescue of the Sp8 mutant phenotype by reducing Sonic Hedgehog (SHH) signaling. These results show that Sp8 primarily functions to promote Fgf expression in the ANR and OP signaling centers that drive the survival, proliferation, and differentiation of the NC and paraxial

  14. A genetic interaction map of cell cycle regulators

    PubMed Central

    Billmann, Maximilian; Horn, Thomas; Fischer, Bernd; Sandmann, Thomas; Huber, Wolfgang; Boutros, Michael

    2016-01-01

    Cell-based RNA interference (RNAi) is a powerful approach to screen for modulators of many cellular processes. However, resulting candidate gene lists from cell-based assays comprise diverse effectors, both direct and indirect, and further dissecting their functions can be challenging. Here we screened a genome-wide RNAi library for modulators of mitosis and cytokinesis in Drosophila S2 cells. The screen identified many previously known genes as well as modulators that have previously not been connected to cell cycle control. We then characterized ∼300 candidate modifiers further by genetic interaction analysis using double RNAi and a multiparametric, imaging-based assay. We found that analyzing cell cycle–relevant phenotypes increased the sensitivity for associating novel gene function. Genetic interaction maps based on mitotic index and nuclear size grouped candidates into known regulatory complexes of mitosis or cytokinesis, respectively, and predicted previously uncharacterized components of known processes. For example, we confirmed a role for the Drosophila CCR4 mRNA processing complex component l(2)NC136 during the mitotic exit. Our results show that the combination of genome-scale RNAi screening and genetic interaction analysis using process-directed phenotypes provides a powerful two-step approach to assigning components to specific pathways and complexes. PMID:26912791

  15. Mitochondrial Protein Interaction Mapping Identifies Regulators of Respiratory Chain Function.

    PubMed

    Floyd, Brendan J; Wilkerson, Emily M; Veling, Mike T; Minogue, Catie E; Xia, Chuanwu; Beebe, Emily T; Wrobel, Russell L; Cho, Holly; Kremer, Laura S; Alston, Charlotte L; Gromek, Katarzyna A; Dolan, Brendan K; Ulbrich, Arne; Stefely, Jonathan A; Bohl, Sarah L; Werner, Kelly M; Jochem, Adam; Westphall, Michael S; Rensvold, Jarred W; Taylor, Robert W; Prokisch, Holger; Kim, Jung-Ja P; Coon, Joshua J; Pagliarini, David J

    2016-08-18

    Mitochondria are essential for numerous cellular processes, yet hundreds of their proteins lack robust functional annotation. To reveal functions for these proteins (termed MXPs), we assessed condition-specific protein-protein interactions for 50 select MXPs using affinity enrichment mass spectrometry. Our data connect MXPs to diverse mitochondrial processes, including multiple aspects of respiratory chain function. Building upon these observations, we validated C17orf89 as a complex I (CI) assembly factor. Disruption of C17orf89 markedly reduced CI activity, and its depletion is found in an unresolved case of CI deficiency. We likewise discovered that LYRM5 interacts with and deflavinates the electron-transferring flavoprotein that shuttles electrons to coenzyme Q (CoQ). Finally, we identified a dynamic human CoQ biosynthetic complex involving multiple MXPs whose topology we map using purified components. Collectively, our data lend mechanistic insight into respiratory chain-related activities and prioritize hundreds of additional interactions for further exploration of mitochondrial protein function. PMID:27499296

  16. Protons as second messenger regulators of G protein signaling

    PubMed Central

    Isom, Daniel G.; Sridharan, Vishwajith; Baker, Rachael; Clement, Sarah T.; Smalley, David M.; Dohlman, Henrik G.

    2013-01-01

    Summary In response to environmental stress cells often generate pH signals that serve to protect vital cellular components and reprogram gene expression for survival. A major barrier to our understanding of this process has been the identification of signaling proteins that detect changes in intracellular pH. To identify candidate pH sensors we developed a computer algorithm that searches proteins for networks of proton-binding sidechains. This analysis indicates that Gα subunits, the principal transducers of G protein-coupled receptor signals, are pH sensors. Our structure-based calculations and biophysical investigations reveal that Gα subunits contain networks of pH-sensing sidechains buried between their Ras and helical domains. We show further that proton binding induces changes in conformation that promote Gα phosphorylation and suppress receptor-initiated signaling. Together, our computational, biophysical and cellular analyses reveal a new and unexpected function for G proteins as mediators of stress-response signaling. PMID:23954348

  17. ROS Homeostasis Regulates Somatic Embryogenesis via the Regulation of Auxin Signaling in Cotton*

    PubMed Central

    Zhou, Ting; Yang, Xiyan; Guo, Kai; Deng, Jinwu; Xu, Jiao; Gao, Wenhui; Lindsey, Keith; Zhang, Xianlong

    2016-01-01

    Somatic embryogenesis (S.E.) is a versatile model for understanding the mechanisms of plant embryogenesis and a useful tool for plant propagation. To decipher the intricate molecular program and potentially to control the parameters affecting the frequency of S.E., a proteomics approach based on two-dimensional gel electrophoresis (2-DE) combined with MALDI-TOF/TOF was used. A total of 149 unique differentially expressed proteins (DEPs) were identified at different stages of cotton S.E. compared with the initial control (0 h explants). The expression profile and functional annotation of these DEPs revealed that S.E. activated stress-related proteins, including several reactive oxygen species (ROS)-scavenging enzymes. Proteins implicated in metabolic, developmental, and reproductive processes were also identified. Further experiments were performed to confirm the role of ROS-scavenging enzymes, suggesting the involvement of ROS homeostasis during S.E. in cotton. Suppressing the expression of specifically identified GhAPX proteins resulted in the inhibition of dedifferentiation. Accelerated redifferentiation was observed in the suppression lines of GhAPXs or GhGSTL3 in parallel with the alteration of endogenous ascorbate metabolism and accumulation of endogenous H2O2 content. Moreover, disrupting endogenous redox homeostasis through the application of high concentrations of DPI, H2O2, BSO, or GSH inhibited the dedifferentiation of cotton explants. Mild oxidation induced through BSO treatment facilitated the transition from embryogenic calluses (ECs) to somatic embryos. Meanwhile, auxin homeostasis was altered through the perturbation of ROS homeostasis by chemical treatments or suppression of ROS-scavenging proteins, along with the activating/suppressing the transcription of genes related to auxin transportation and signaling. These results show that stress responses are activated during S.E. and may regulate the ROS homeostasis by interacting with auxin signaling

  18. ROS Homeostasis Regulates Somatic Embryogenesis via the Regulation of Auxin Signaling in Cotton.

    PubMed

    Zhou, Ting; Yang, Xiyan; Guo, Kai; Deng, Jinwu; Xu, Jiao; Gao, Wenhui; Lindsey, Keith; Zhang, Xianlong

    2016-06-01

    Somatic embryogenesis (S.E.) is a versatile model for understanding the mechanisms of plant embryogenesis and a useful tool for plant propagation. To decipher the intricate molecular program and potentially to control the parameters affecting the frequency of S.E., a proteomics approach based on two-dimensional gel electrophoresis (2-DE) combined with MALDI-TOF/TOF was used. A total of 149 unique differentially expressed proteins (DEPs) were identified at different stages of cotton S.E. compared with the initial control (0 h explants). The expression profile and functional annotation of these DEPs revealed that S.E. activated stress-related proteins, including several reactive oxygen species (ROS)-scavenging enzymes. Proteins implicated in metabolic, developmental, and reproductive processes were also identified. Further experiments were performed to confirm the role of ROS-scavenging enzymes, suggesting the involvement of ROS homeostasis during S.E. in cotton. Suppressing the expression of specifically identified GhAPX proteins resulted in the inhibition of dedifferentiation. Accelerated redifferentiation was observed in the suppression lines of GhAPXs or GhGSTL3 in parallel with the alteration of endogenous ascorbate metabolism and accumulation of endogenous H2O2 content. Moreover, disrupting endogenous redox homeostasis through the application of high concentrations of DPI, H2O2, BSO, or GSH inhibited the dedifferentiation of cotton explants. Mild oxidation induced through BSO treatment facilitated the transition from embryogenic calluses (ECs) to somatic embryos. Meanwhile, auxin homeostasis was altered through the perturbation of ROS homeostasis by chemical treatments or suppression of ROS-scavenging proteins, along with the activating/suppressing the transcription of genes related to auxin transportation and signaling. These results show that stress responses are activated during S.E. and may regulate the ROS homeostasis by interacting with auxin signaling

  19. Mapping

    ERIC Educational Resources Information Center

    Kinney, Douglas M.; McIntosh, Willard L.

    1978-01-01

    Geologic mapping in the United States increased by about one-quarter in the past year. Examinations of mapping trends were in the following categories: (1) Mapping at scales of 1:100, 000; (2) Metric-scale base maps; (3) International mapping, and (4) Planetary mapping. (MA)

  20. Post-Transcriptional Regulation of Interferons and Their Signaling Pathways

    PubMed Central

    2014-01-01

    Interferons (IFNs) are low molecular weight cell-derived proteins that include the type I, II, and III IFN families. IFNs are critical for an optimal immune response during microbial infections while dysregulated expression can lead to autoimmune diseases. Given its role in disease, it is important to understand cellular mechanisms of IFN regulation. 3′ untranslated regions (3′ UTRs) have emerged as potent regulators of mRNA and protein dosage and are controlled through multiple regulatory elements including adenylate uridylate (AU)-rich elements (AREs) and microRNA (miRNA) recognition elements. These AREs are targeted by RNA-binding proteins (ARE-BPs) for degradation and/or stabilization through an ARE-mediated decay process. miRNA are endogenous, single-stranded RNA molecules ∼22 nucleotides in length that regulate mRNA translation through the miRNA-induced silencing complex. IFN transcripts, like other labile mRNAs, harbor AREs in their 3′ UTRs that dictate the turnover of mRNA. This review is a survey of the literature related to IFN regulation by miRNA, ARE-BPs, and how these complexes interact dynamically on the 3′ UTR. Additionally, downstream effects of these post-transcriptional regulators on the immune response will be discussed. Review topics include past studies, current understanding, and future challenges in the study of post-transcriptional regulation affecting IFN responses. PMID:24702117

  1. Light-regulated translocation of signaling proteins in Drosophila photoreceptors

    PubMed Central

    Frechter, Shahar; Minke, Baruch

    2007-01-01

    Illumination of Drosophila photoreceptor cells induces multi-facet responses, which include generation of the photoreceptor potential, screening pigment migration and translocation of signaling proteins which is the focus of recent extensive research. Translocation of three signaling molecules is covered in this review: (1) Light-dependent translocation of arrestin from the cytosol to the signaling membrane, the rhabdomere, determines the lifetime of activated rhodopsin. Arrestin translocates in PIP3 and NINAC myosin III dependent manner, and specific mutations which disrupt the interaction between arrestin and PIP3 or NINAC also impair the light-dependant translocation of arrestin and the termination of the response to light. (2) Activation of Drosophila visual G protein, DGq, causes a massive and reversible, translocation of the α subunit from the signaling membrane to the cytosol, accompanied by activity-dependent architectural changes. Analysis of the translocation and the recovery kinetics of DGqα in wild-type flies and specific visual mutants indicated that DGqα is necessary but not sufficient for the architectural changes. (3) The TRP-like (TRPL) but not TRP channels translocate in a light-dependent manner between the rhabdomere and the cell body. As a physiological consequence of this light-dependent modulation of the TRP/TRPL ratio, the photoreceptors of dark-adapted flies operate at a wider dynamic range, which allows the photoreceptors enriched with TRPL to function better in darkness and dim background illumination. Altogether, signal-dependent movement of signaling proteins plays a major role in the maintenance and function of photoreceptor cells. PMID:16458490

  2. The Multiple Signaling Systems Regulating Virulence in Pseudomonas aeruginosa

    PubMed Central

    Nadal Jimenez, Pol; Koch, Gudrun; Thompson, Jessica A.; Xavier, Karina B.; Cool, Robbert H.

    2012-01-01

    Summary: Cell-to-cell communication is a major process that allows bacteria to sense and coordinately react to the fluctuating conditions of the surrounding environment. In several pathogens, this process triggers the production of virulence factors and/or a switch in bacterial lifestyle that is a major determining factor in the outcome and severity of the infection. Understanding how bacteria control these signaling systems is crucial to the development of novel antimicrobial agents capable of reducing virulence while allowing the immune system of the host to clear bacterial infection, an approach likely to reduce the selective pressures for development of resistance. We provide here an up-to-date overview of the molecular basis and physiological implications of cell-to-cell signaling systems in Gram-negative bacteria, focusing on the well-studied bacterium Pseudomonas aeruginosa. All of the known cell-to-cell signaling systems in this bacterium are described, from the most-studied systems, i.e., N-acyl homoserine lactones (AHLs), the 4-quinolones, the global activator of antibiotic and cyanide synthesis (GAC), the cyclic di-GMP (c-di-GMP) and cyclic AMP (cAMP) systems, and the alarmones guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp), to less-well-studied signaling molecules, including diketopiperazines, fatty acids (diffusible signal factor [DSF]-like factors), pyoverdine, and pyocyanin. This overview clearly illustrates that bacterial communication is far more complex than initially thought and delivers a clear distinction between signals that are quorum sensing dependent and those relying on alternative factors for their production. PMID:22390972

  3. Cellular defense processes regulated by pathogen-elicited receptor signaling

    NASA Astrophysics Data System (ADS)

    Wu, Rongcong; Goldsipe, Arthur; Schauer, David B.; Lauffenburger, Douglas A.

    2011-06-01

    Vertebrates are constantly threatened by the invasion of microorganisms and have evolved systems of immunity to eliminate infectious pathogens in the body. Initial sensing of microbial agents is mediated by the recognition of pathogens by means of molecular structures expressed uniquely by microbes of a given type. So-called 'Toll-like receptors' are expressed on host epithelial barrier cells play an essential role in the host defense against microbial pathogens by inducing cell responses (e.g., proliferation, death, cytokine secretion) via activation of intracellular signaling networks. As these networks, comprising multiple interconnecting dynamic pathways, represent highly complex multi-variate "information processing" systems, the signaling activities particularly critical for governing the host cell responses are poorly understood and not easily ascertained by a priori theoretical notions. We have developed over the past half-decade a "data-driven" computational modeling approach, on a 'cue-signal-response' combined experiment/computation paradigm, to elucidate key multi-variate signaling relationships governing the cell responses. In an example presented here, we study how a canonical set of six kinase pathways combine to effect microbial agent-induced apoptotic death of a macrophage cell line. One modeling technique, partial least-squares regression, yielded the following key insights: {a} signal combinations most strongly correlated to apoptotic death are orthogonal to those most strongly correlated with release of inflammatory cytokines; {b} the ratio of two key pathway activities is the most powerful predictor of microbe-induced macrophage apoptotic death; {c} the most influential time-window of this signaling activity ratio is surprisingly fast: less than one hour after microbe stimulation.

  4. Protein kinase C in the immune system: from signalling to chromatin regulation.

    PubMed

    Lim, Pek Siew; Sutton, Christopher Ray; Rao, Sudha

    2015-12-01

    Protein kinase C (PKC) form a key family of enzymes involved in signalling pathways that specifically phosphorylates substrates at serine/threonine residues. Phosphorylation by PKC is important in regulating a variety of cellular events such as cell proliferation and the regulation of gene expression. In the immune system, PKCs are involved in regulating signal transduction pathways important for both innate and adaptive immunity, ultimately resulting in the expression of key immune genes. PKCs act as mediators during immune cell signalling through the immunological synapse. PKCs are traditionally known to be cytoplasmic signal transducers and are well embedded in the signalling pathways of cells to mediate the cells' response to a stimulus from the plasma membrane to the nucleus. PKCs are also found to transduce signals within the nucleus, a process that is distinct from the cytoplasmic signalling pathway. There is now growing evidence suggesting that PKC can directly regulate gene expression programmes through a non-traditional role as nuclear kinases. In this review, we will focus on the role of PKCs as key cytoplasmic signal transducers in immune cell signalling, as well as its role in nuclear signal transduction. We will also highlight recent evidence for its newly discovered regulatory role in the nucleus as a chromatin-associated kinase.

  5. Extracellular signals and receptor-like kinases regulating ROP GTPases in plants

    PubMed Central

    Miyawaki, Kaori N.; Yang, Zhenbiao

    2014-01-01

    Rho-like GTPase from plants (ROPs) function as signaling switches that control a wide variety of cellular functions and behaviors including cell morphogenesis, cell division and cell differentiation. The Arabidopsis thaliana genome encodes 11 ROPs that form a distinct single subfamily contrarily to animal or fungal counterparts where multiple subfamilies of Rho GTPases exist. Since Rho proteins bind to their downstream effector proteins only in their GTP-bound “active” state, the activation of ROPs by upstream factor(s) is a critical step in the regulation of ROP signaling. Therefore, it is critical to examine the input signals that lead to the activation of ROPs. Recent findings showed that the plant hormone auxin is an important signal for the activation of ROPs during pavement cell morphogenesis as well as for other developmental processes. In contrast to auxin, another plant hormone, abscisic acid, negatively regulates ROP signaling. Calcium is another emerging signal in the regulation of ROP signaling. Several lines of evidence indicate that plasma membrane localized-receptor like kinases play a critical role in the transmission of the extracellular signals to intracellular ROP signaling pathways. This review focuses on how these signals impinge upon various direct regulators of ROPs to modulate various plant processes. PMID:25295042

  6. Diffeomorphic metric mapping and probabilistic atlas generation of hybrid diffusion imaging based on BFOR signal basis.

    PubMed

    Du, Jia; Hosseinbor, A Pasha; Chung, Moo K; Bendlin, Barbara B; Suryawanshi, Gaurav; Alexander, Andrew L; Qiu, Anqi

    2014-10-01

    We first propose a large deformation diffeomorphic metric mapping algorithm to align multiple b-value diffusion weighted imaging (mDWI) data, specifically acquired via hybrid diffusion imaging (HYDI). We denote this algorithm as LDDMM-HYDI. We then propose a Bayesian probabilistic model for estimating the white matter atlas from HYDIs. We adopt the work given in Hosseinbor et al. (2013) and represent the q-space diffusion signal with the Bessel Fourier orientation reconstruction (BFOR) signal basis. The BFOR framework provides the representation of mDWI in the q-space and the analytic form of the emsemble average propagator (EAP) reconstruction, as well as reduces memory requirement. In addition, since the BFOR signal basis is orthonormal, the L(2) norm that quantifies the differences in the q-space signals of any two mDWI datasets can be easily computed as the sum of the squared differences in the BFOR expansion coefficients. In this work, we show that the reorientation of the q-space signal due to spatial transformation can be easily defined on the BFOR signal basis. We incorporate the BFOR signal basis into the LDDMM framework and derive the gradient descent algorithm for LDDMM-HYDI with explicit orientation optimization. Additionally, we extend the previous Bayesian atlas estimation framework for scalar-valued images to HYDIs and derive the expectation-maximization algorithm for solving the HYDI atlas estimation problem. Using real HYDI datasets, we show that the Bayesian model generates the white matter atlas with anatomical details. Moreover, we show that it is important to consider the variation of mDWI reorientation due to a small change in diffeomorphic transformation in the LDDMM-HYDI optimization and to incorporate the full information of HYDI for aligning mDWI. Finally, we show that the LDDMM-HYDI outperforms the LDDMM algorithm with diffusion tensors generated from each shell of HYDI.

  7. Extracellular simian virus 40 induces an ERK/MAP kinase-independent signalling pathway that activates primary response genes and promotes virus entry.

    PubMed

    Dangoria, N S; Breau, W C; Anderson, H A; Cishek, D M; Norkin, L C

    1996-09-01

    Simian virus 40 (SV40) binding to growth-arrested cells activated an intracellular signalling pathway that induced the up-regulation of the primary response genes c-myc, c-jun and c-sis within 30 min and of JE within 90 min. The up-regulation of the primary response genes occurred in the presence of cycloheximide and when UV-inactivated SV40 was adsorbed to cells. SV40 binding did not activate Raf or mitogen-activated protein kinase (MAP/ERK1), or mobilize intracellular Ca2+. The SV40-induced up-regulation of c-myc and c-jun was blocked by the tyrosine kinase inhibitor, genistein, and by the protein kinase C (PKC) inhibitor, calphostin C, but not by expression of the MAP kinase-specific phosphatase, MKP-1. These results suggest that the SV40-induced signalling pathway includes the activities of a tyrosine kinase and a Ca(2+)-independent isoform of PKC, but not of Raf or MAP kinase. Finally, SV40 infectious entry into cells was specifically and reversibly blocked by genistein.

  8. Nolz1 promotes striatal neurogenesis through the regulation of retinoic acid signaling

    PubMed Central

    2010-01-01

    Background Nolz1 is a zinc finger transcription factor whose expression is enriched in the lateral ganglionic eminence (LGE), although its function is still unknown. Results Here we analyze the role of Nolz1 during LGE development. We show that Nolz1 expression is high in proliferating neural progenitor cells (NPCs) of the LGE subventricular zone. In addition, low levels of Nolz1 are detected in the mantle zone, as well as in the adult striatum. Similarly, Nolz1 is highly expressed in proliferating LGE-derived NPC cultures, but its levels rapidly decrease upon cell differentiation, pointing to a role of Nolz1 in the control of NPC proliferation and/or differentiation. In agreement with this hypothesis, we find that Nolz1 over-expression promotes cell cycle exit of NPCs in neurosphere cultures and negatively regulates proliferation in telencephalic organotypic cultures. Within LGE primary cultures, Nolz1 over-expression promotes the acquisition of a neuronal phenotype, since it increases the number of β-III tubulin (Tuj1)- and microtubule-associated protein (MAP)2-positive neurons, and inhibits astrocyte generation and/or differentiation. Retinoic acid (RA) is one of the most important morphogens involved in striatal neurogenesis, and regulates Nolz1 expression in different systems. Here we show that Nolz1 also responds to this morphogen in E12.5 LGE-derived cell cultures. However, Nolz1 expression is not regulated by RA in E14.5 LGE-derived cell cultures, nor is it affected during LGE development in mouse models that present decreased RA levels. Interestingly, we find that Gsx2, which is necessary for normal RA signaling during LGE development, is also required for Nolz1 expression, which is lost in Gsx2 knockout mice. These findings suggest that Nolz1 might act downstream of Gsx2 to regulate RA-induced neurogenesis. Keeping with this hypothesis, we show that Nolz1 induces the selective expression of the RA receptor (RAR)β without altering RARα or RARγ. In

  9. The Tec Kinase-Regulated Phosphoproteome Reveals a Mechanism for the Regulation of Inhibitory Signals in Murine Macrophages.

    PubMed

    Tampella, Giacomo; Kerns, Hannah M; Niu, Deqiang; Singh, Swati; Khim, Socheath; Bosch, Katherine A; Garrett, Meghan E; Moguche, Albanus; Evans, Erica; Browning, Beth; Jahan, Tahmina A; Nacht, Mariana; Wolf-Yadlin, Alejandro; Plebani, Alessandro; Hamerman, Jessica A; Rawlings, David J; James, Richard G

    2015-07-01

    Previous work has shown conflicting roles for Tec family kinases in regulation of TLR-dependent signaling in myeloid cells. In the present study, we performed a detailed investigation of the role of the Tec kinases Btk and Tec kinases in regulating TLR signaling in several types of primary murine macrophages. We demonstrate that primary resident peritoneal macrophages deficient for Btk and Tec secrete less proinflammatory cytokines in response to TLR stimulation than do wild-type cells. In contrast, we found that bone marrow-derived and thioglycollate-elicited peritoneal macrophages deficient for Btk and Tec secrete more proinflammatory cytokines than do wild-type cells. We then compared the phosphoproteome regulated by Tec kinases and LPS in primary peritoneal and bone marrow-derived macrophages. From this analysis we determined that Tec kinases regulate different signaling programs in these cell types. In additional studies using bone marrow-derived macrophages, we found that Tec and Btk promote phosphorylation events necessary for immunoreceptor-mediated inhibition of TLR signaling. Taken together, our results are consistent with a model where Tec kinases (Btk, Tec, Bmx) are required for TLR-dependent signaling in many types of myeloid cells. However, our data also support a cell type-specific TLR inhibitory role for Btk and Tec that is mediated by immunoreceptor activation and signaling via PI3K. PMID:26026062

  10. The Tec kinase-regulated phosphoproteome reveals a mechanism for the regulation of inhibitory signals in murine macrophages

    PubMed Central

    Tampella, Giacomo; Kerns, Hannah M.; Niu, Deqiang; Singh, Swati; Khim, Socheath; Bosch, Katherine A.; Garrett, Meghan E.; Moguche, Albanus; Evans, Erica; Browning, Beth; Jahan, Tahmina A.; Nacht, Mariana; Wolf-Yadlin, Alejandro; Plebani, Alessandro; Hamerman, Jessica A.; Rawlings, David J.; James, Richard G.

    2015-01-01

    Previous work has shown conflicting roles for Tec family kinases in regulation of Toll-like receptor (TLR)-dependent signalling in myeloid cells. In the present study, we performed a detailed investigation of the role of Btk and Tec kinases in regulating TLR signalling in several types of primary murine macrophages. We demonstrate that primary resident peritoneal macrophages deficient for Btk and Tec secrete less pro-inflammatory cytokines in response to TLR stimulation than wild type cells. In contrast, we found that bone marrow-derived and thioglycollate-elicited peritoneal macrophages deficient for Btk and Tec secrete more pro-inflammatory cytokines than wild type cells. We then compared the phosphoproteome regulated by Tec kinases and lipopolysaccharide in primary peritoneal and bone marrow derived macrophages. From this analysis we determined that Tec kinases regulate different signalling programs in these cell types. In additional studies using bone marrow-derived macrophages, we find that Tec and Btk promote phosphorylation events necessary for immunoreceptor-mediated inhibition of TLR signalling. Taken together, our results are consistent with a model where Tec kinases (Btk, Tec, Bmx) are required for TLR-dependent signalling in many types of myeloid cells. However, our data also support a cell type-specific TLR-inhibitory role for Btk and Tec that is mediated by immunoreceptor activation and signalling via PI3K. PMID:26026062

  11. Nitric Oxide Regulation of H-NOX Signaling Pathways in Bacteria.

    PubMed

    Nisbett, Lisa-Marie; Boon, Elizabeth M

    2016-09-01

    Nitric oxide (NO) is a freely diffusible, radical gas that has now been established as an integral signaling molecule in eukaryotes and bacteria. It has been demonstrated that NO signaling is initiated upon ligation to the heme iron of an H-NOX domain in mammals and in some bacteria. Bacterial H-NOX proteins have been found to interact with enzymes that participate in signaling pathways and regulate bacterial processes such as quorum sensing, biofilm formation, and symbiosis. Here, we review the biochemical characterization of these signaling pathways and, where available, describe how ligation of NO to H-NOX specifically regulates the activity of these pathways and their associated bacterial phenotypes.

  12. Mutations in Transcriptional Regulators Allow Selective Engineering of Signal Integration Logic

    PubMed Central

    2014-01-01

    ABSTRACT Bacterial cells monitor their environment by sensing a set of signals. Typically, these environmental signals affect promoter activities by altering the activity of transcription regulatory proteins. Promoters are often regulated by more than one regulatory protein, and in these cases the relevant signals are integrated by certain logic. In this work, we study how single amino acid substitutions in a regulatory protein (GalR) affect transcriptional regulation and signal integration logic at a set of engineered promoters. Our results suggest that point mutations in regulatory genes allow independent evolution of regulatory logic at different promoters. PMID:24961691

  13. Cellular Architecture Regulates Collective Calcium Signaling and Cell Contractility

    PubMed Central

    Hoying, James B.; Deymier, Pierre A.; Zhang, Donna D.; Wong, Pak Kin

    2016-01-01

    A key feature of multicellular systems is the ability of cells to function collectively in response to external stimuli. However, the mechanisms of intercellular cell signaling and their functional implications in diverse vascular structures are poorly understood. Using a combination of computational modeling and plasma lithography micropatterning, we investigate the roles of structural arrangement of endothelial cells in collective calcium signaling and cell contractility. Under histamine stimulation, endothelial cells in self-assembled and microengineered networks, but not individual cells and monolayers, exhibit calcium oscillations. Micropatterning, pharmacological inhibition, and computational modeling reveal that the calcium oscillation depends on the number of neighboring cells coupled via gap junctional intercellular communication, providing a mechanistic basis of the architecture-dependent calcium signaling. Furthermore, the calcium oscillation attenuates the histamine-induced cytoskeletal reorganization and cell contraction, resulting in differential cell responses in an architecture-dependent manner. Taken together, our results suggest that endothelial cells can sense and respond to chemical stimuli according to the vascular architecture via collective calcium signaling. PMID:27196735

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

    SciTech Connect

    Liao, J.C.

    2000-05-08

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

  15. Maize LAZY1 mediates shoot gravitropism and inflorescence development through regulating auxin transport, auxin signaling, and light response.

    PubMed

    Dong, Zhaobin; Jiang, Chuan; Chen, Xiaoyang; Zhang, Tao; Ding, Lian; Song, Weibin; Luo, Hongbing; Lai, Jinsheng; Chen, Huabang; Liu, Renyi; Zhang, Xiaolan; Jin, Weiwei

    2013-11-01

    Auxin is a plant hormone that plays key roles in both shoot gravitropism and inflorescence development. However, these two processes appear to be parallel and to be regulated by distinct players. Here, we report that the maize (Zea mays) prostrate stem1 mutant, which is allelic to the classic mutant lazy plant1 (la1), displays prostrate growth with reduced shoot gravitropism and defective inflorescence development. Map-based cloning identified maize ZmLA1 as the functional ortholog of LAZY1 in rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana). It has a unique role in inflorescence development and displays enriched expression in reproductive organs such as tassels and ears. Transcription of ZmLA1 responds to auxin and is repressed by light. Furthermore, ZmLA1 physically interacts with a putative auxin transport regulator in the plasma membrane and a putative auxin signaling protein in the nucleus. RNA-SEQ data showed that dozens of auxin transport, auxin response, and light signaling genes were differentially expressed in la1 mutant stems. Therefore, ZmLA1 might mediate the cross talk between shoot gravitropism and inflorescence development by regulating auxin transport, auxin signaling, and probably light response in maize. PMID:24089437

  16. Maize LAZY1 mediates shoot gravitropism and inflorescence development through regulating auxin transport, auxin signaling, and light response.

    PubMed

    Dong, Zhaobin; Jiang, Chuan; Chen, Xiaoyang; Zhang, Tao; Ding, Lian; Song, Weibin; Luo, Hongbing; Lai, Jinsheng; Chen, Huabang; Liu, Renyi; Zhang, Xiaolan; Jin, Weiwei

    2013-11-01

    Auxin is a plant hormone that plays key roles in both shoot gravitropism and inflorescence development. However, these two processes appear to be parallel and to be regulated by distinct players. Here, we report that the maize (Zea mays) prostrate stem1 mutant, which is allelic to the classic mutant lazy plant1 (la1), displays prostrate growth with reduced shoot gravitropism and defective inflorescence development. Map-based cloning identified maize ZmLA1 as the functional ortholog of LAZY1 in rice (Oryza sativa) and Arabidopsis (Arabidopsis thaliana). It has a unique role in inflorescence development and displays enriched expression in reproductive organs such as tassels and ears. Transcription of ZmLA1 responds to auxin and is repressed by light. Furthermore, ZmLA1 physically interacts with a putative auxin transport regulator in the plasma membrane and a putative auxin signaling protein in the nucleus. RNA-SEQ data showed that dozens of auxin transport, auxin response, and light signaling genes were differentially expressed in la1 mutant stems. Therefore, ZmLA1 might mediate the cross talk between shoot gravitropism and inflorescence development by regulating auxin transport, auxin signaling, and probably light response in maize.

  17. PIF4 Integrates Multiple Environmental and Hormonal Signals for Plant Growth Regulation in Arabidopsis

    PubMed Central

    Choi, Hyunmo; Oh, Eunkyoo

    2016-01-01

    As sessile organisms, plants must be able to adapt to the environment. Plants respond to the environment by adjusting their growth and development, which is mediated by sophisticated signaling networks that integrate multiple environmental and endogenous signals. Recently, increasing evidence has shown that a bHLH transcription factor PIF4 plays a major role in the multiple signal integration for plant growth regulation. PIF4 is a positive regulator in cell elongation and its activity is regulated by various environmental signals, including light and temperature, and hormonal signals, including auxin, gibberellic acid and brassinosteroid, both transcriptionally and post-translationally. Moreover, recent studies have shown that the circadian clock and metabolic status regulate endogenous PIF4 level. The PIF4 transcription factor cooperatively regulates the target genes involved in cell elongation with hormone-regulated transcription factors. Therefore, PIF4 is a key integrator of multiple signaling pathways, which optimizes growth in the environment. This review will discuss our current understanding of the PIF4-mediated signaling networks that control plant growth. PMID:27432188

  18. PIF4 Integrates Multiple Environmental and Hormonal Signals for Plant Growth Regulation in Arabidopsis.

    PubMed

    Choi, Hyunmo; Oh, Eunkyoo

    2016-08-31

    As sessile organisms, plants must be able to adapt to the environment. Plants respond to the environment by adjusting their growth and development, which is mediated by sophisticated signaling networks that integrate multiple environmental and endogenous signals. Recently, increasing evidence has shown that a bHLH transcription factor PIF4 plays a major role in the multiple signal integration for plant growth regulation. PIF4 is a positive regulator in cell elongation and its activity is regulated by various environmental signals, including light and temperature, and hormonal signals, including auxin, gibberellic acid and brassinosteroid, both transcriptionally and post-translationally. Moreover, recent studies have shown that the circadian clock and metabolic status regulate endogenous PIF4 level. The PIF4 transcription factor cooperatively regulates the target genes involved in cell elongation with hormone-regulated transcription factors. Therefore, PIF4 is a key integrator of multiple signaling pathways, which optimizes growth in the environment. This review will discuss our current understanding of the PIF4-mediated signaling networks that control plant growth. PMID:27432188

  19. Assessing the Health Impacts of Air Pollution Regulations Using BenMAP, the Environmental Benefits Mapping and Analysis Program

    NASA Astrophysics Data System (ADS)

    Hubbell, B.; McCubbin, D.; Hallberg, A.

    2003-12-01

    The U.S. EPA Office of Air and Radiation has developed BenMAP, the environmental Benefits Mapping and Analysis Program, a new software tool for estimating the health and environmental impacts of environmental regulations. BenMAP is the US EPA's premier tool for estimating benefits associated with air pollution reduction strategies, and has recently been used in evaluating US EPA's Proposed Non-Road Diesel Vehicle Standards and the proposed Clear Skies Act legislation. BenMAP is a geographic information system (GIS) that uses modeled and monitored air quality data combined with population forecasts to develop estimates of changes in community level exposure to ambient environmental pollution (currently ambient air pollution, e.g. ozone and PM). These estimated changes in exposure to ambient pollution are used as inputs to concentration-response functions derived from the epidemiological literature, along with data on baseline incidence of health effects, i.e. county level age and cause specific mortality rates. The resulting point estimates of changes in incidence of health effects, along with their associated uncertainty distributions (currently based on reported standard errors in the literature), are then multiplied by economic unit values (represented by distributions), i.e. the cost of a hospital admission, to derive dollar estimates of health benefits. BenMAP is unique in that it uses highly detailed census and health data matched with spatially detailed environmental quality data to estimate health benefits. The program can also provide estimates of the uncertainty associated with the estimated benefits. Other features of the program include the ability to pool results from multiple studies of the same endpoint, using fixed or random effects weights, or user supplied weights. BenMAP also incorporates functions to manipulate and combine information on environmental quality from many different sources. For the current version focusing on air pollution, these

  20. 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

  1. ROP GTPase Signaling in The Hormonal Regulation of Plant Growth

    SciTech Connect

    Yang, Zhenbiao

    2013-05-24

    I secured funding from the DOE to investigate the effect of auxin signaling on ROP9. This was based on our preliminary data showing that ROP9 is activated by auxin. However, we were unable to show that rop9 knockout mutants have altered sensitivity to auxin. Instead, we found that auxin activates both ROP2 and ROP6, and relevant mutants exhibit reduced sensitivity to auxin. Therefore we used the fund to strengthen our research on ROP2 and ROP6. My laboratory made major advancements in the recent years in the understanding of the effect of auxin signaling on ROP2 and ROP6. This is clearly exemplified by the numerous publications acknowledging fund DE-FG0204ER15555 as the source of funding.

  2. Dendritic Spines as Tunable Regulators of Synaptic Signals

    PubMed Central

    Tønnesen, Jan; Nägerl, U. Valentin

    2016-01-01

    Neurons are perpetually receiving vast amounts of information in the form of synaptic input from surrounding cells. The majority of input occurs at thousands of dendritic spines, which mediate excitatory synaptic transmission in the brain, and is integrated by the dendritic and somatic compartments of the postsynaptic neuron. The functional role of dendritic spines in shaping biochemical and electrical signals transmitted via synapses has long been intensely studied. Yet, many basic questions remain unanswered, in particular regarding the impact of their nanoscale morphology on electrical signals. Here, we review our current understanding of the structure and function relationship of dendritic spines, focusing on the controversy of electrical compartmentalization and the potential role of spine structural changes in synaptic plasticity. PMID:27340393

  3. Spatially coordinated kinase signaling regulates local axon degeneration.

    PubMed

    Chen, Mark; Maloney, Janice A; Kallop, Dara Y; Atwal, Jasvinder K; Tam, Stephen J; Baer, Kristin; Kissel, Holger; Kaminker, Joshua S; Lewcock, Joseph W; Weimer, Robby M; Watts, Ryan J

    2012-09-26

    In addition to being a hallmark of neurodegenerative disease, axon degeneration is used during development of the nervous system to prune unwanted connections. In development, axon degeneration is tightly regulated both temporally and spatially. Here, we provide evidence that degeneration cues are transduced through various kinase pathways functioning in spatially distinct compartments to regulate axon degeneration. Intriguingly, glycogen synthase kinase-3 (GSK3) acts centrally, likely modulating gene expression in the cell body to regulate distally restricted axon degeneration. Through a combination of genetic and pharmacological manipulations, including the generation of an analog-sensitive kinase allele mutant mouse for GSK3β, we show that the β isoform of GSK3, not the α isoform, is essential for developmental axon pruning in vitro and in vivo. Additionally, we identify the dleu2/mir15a/16-1 cluster, previously characterized as a regulator of B-cell proliferation, and the transcription factor tbx6, as likely downstream effectors of GSK3β in axon degeneration.

  4. A self-regulating biomolecular comparator for processing oscillatory signals

    PubMed Central

    Agrawal, Deepak K.; Franco, Elisa; Schulman, Rebecca

    2015-01-01

    While many cellular processes are driven by biomolecular oscillators, precise control of a downstream on/off process by a biochemical oscillator signal can be difficult: over an oscillator's period, its output signal varies continuously between its amplitude limits and spends a significant fraction of the time at intermediate values between these limits. Further, the oscillator's output is often noisy, with particularly large variations in the amplitude. In electronic systems, an oscillating signal is generally processed by a downstream device such as a comparator that converts a potentially noisy oscillatory input into a square wave output that is predominantly in one of two well-defined on and off states. The comparator's output then controls downstream processes. We describe a method for constructing a synthetic biochemical device that likewise produces a square-wave-type biomolecular output for a variety of oscillatory inputs. The method relies on a separation of time scales between the slow rate of production of an oscillatory signal molecule and the fast rates of intermolecular binding and conformational changes. We show how to control the characteristics of the output by varying the concentrations of the species and the reaction rates. We then use this control to show how our approach could be applied to process different in vitro and in vivo biomolecular oscillators, including the p53-Mdm2 transcriptional oscillator and two types of in vitro transcriptional oscillators. These results demonstrate how modular biomolecular circuits could, in principle, be combined to build complex dynamical systems. The simplicity of our approach also suggests that natural molecular circuits may process some biomolecular oscillator outputs before they are applied downstream. PMID:26378119

  5. Notch signaling regulates venous arterialization during zebrafish fin regeneration

    PubMed Central

    Kametani, Yoshiko; Chi, Neil C.; Stainier, Didier Y.R.; Takada, Shinji

    2015-01-01

    In order to protect against blood pressure, a mature artery is supported by mural cells which include vascular smooth muscle cells and pericytes. To regenerate a functional vascular system, arteries should be properly reconstructed with mural cells although the mechanisms underlying artery reconstruction remain unclear. In this study, we examined the process of artery reconstruction during regeneration of the zebrafish caudal fin as a model to study arterial formation in an adult setting. During fin regeneration, the arteries and veins form a net-like vasculature called the vascular plexus, and this plexus undergoes remodeling to form a new artery and 2 flanking veins. We found that the new vascular plexus originates mainly from venous cells in the stump but very rarely from the arterial cells. Interestingly, these vein-derived cells contributed to the reconstructed arteries. This arterialization was dependent on Notch signaling, and further analysis revealed that Notch signaling was required for the initiation of arterial gene expression. In contrast, venous remodeling did not require Notch signaling. These results provide new insights towards understanding mechanisms of vascular regeneration and illustrate the utility of the adult zebrafish fin to study this process. PMID:25810153

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

    PubMed Central

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

    2014-01-01

    Accumulating data indicates that following anti-cancer treatments, cancer cell death can be perceived as immunogenic or tolerogenic by the immune system. The former is made possible due to the ability of certain anti-cancer modalities to induce immunogenic cell death (ICD) that is associated with the emission of damage-associated molecular patterns (DAMPs), which assist in unlocking a sequence of events leading to the development of anti-tumour immunity. In response to ICD inducers, activation of endoplasmic reticulum (ER) stress has been identified to be indispensable to confer the immunogenic character of cancer cell death, due to its ability to coordinate the danger signalling pathways responsible for the trafficking of vital DAMPs and subsequent anti-cancer immune responses. However, in recent times, certain processes apart from ER stress have emerged (e.g., autophagy and possibly viral response-like signature), which have the ability to influence danger signalling. In this review, we discuss the molecular nature, emerging plasticity in the danger signalling mechanisms and immunological impact of known DAMPs in the context of immunogenic cancer cell death. We also discuss key effector mechanisms modulating the interface between dying cancer cells and the immune cells, which we believe are crucial for the therapeutic relevance of ICD in the context of human cancers, and also discuss the influence of experimental conditions and animal models on these. PMID:23686135

  7. Dosage-dependent hedgehog signals integrated with Wnt/β-catenin signaling regulate external genitalia formation as an appendicular program

    PubMed Central

    Miyagawa, Shinichi; Moon, Anne; Haraguchi, Ryuma; Inoue, Chie; Harada, Masayo; Nakahara, Chiaki; Suzuki, Kentaro; Matsumaru, Daisuke; Kaneko, Takehito; Matsuo, Isao; Yang, Lei; Taketo, Makoto M.; Iguchi, Taisen; Evans, Sylvia M.; Yamada, Gen

    2009-01-01

    Embryonic appendicular structures, such as the limb buds and the developing external genitalia, are suitable models with which to analyze the reciprocal interactions of growth factors in the regulation of outgrowth. Although several studies have evaluated the individual functions of different growth factors in appendicular growth, the coordinated function and integration of input from multiple signaling cascades is poorly understood. We demonstrate that a novel signaling cascade governs formation of the embryonic external genitalia [genital tubercle (GT)]. We show that the dosage of Shh signal is tightly associated with subsequent levels of Wnt/β-catenin activity and the extent of external genitalia outgrowth. In Shh-null mouse embryos, both expression of Wnt ligands and Wnt/β-catenin signaling activity are downregulated. β-catenin gain-of-function mutation rescues defective GT outgrowth and Fgf8 expression in Shh-null embryos. These data indicate that Wnt/β-catenin signaling in the distal urethral epithelium acts downstream of Shh signaling during GT outgrowth. The current data also suggest that Wnt/β-catenin regulates Fgf8 expression via Lef/Tcf binding sites in a 3′ conserved enhancer. Fgf8 induces phosphorylation of Erk1/2 and cell proliferation in the GT mesenchyme in vitro, yet Fgf4/8 compound-mutant phenotypes indicate dispensable functions of Fgf4/8 and the possibility of redundancy among multiple Fgfs in GT development. Our results provide new insights into the integration of growth factor signaling in the appendicular developmental programs that regulate external genitalia development. PMID:19906864

  8. Hedgehog Signaling Regulates the Ciliary Transport of Odorant Receptors in Drosophila.

    PubMed

    Sanchez, Gonzalo M; Alkhori, Liza; Hatano, Eduardo; Schultz, Sebastian W; Kuzhandaivel, Anujaianthi; Jafari, Shadi; Granseth, Björn; Alenius, Mattias

    2016-01-26

    Hedgehog (Hh) signaling is a key regulatory pathway during development and also has a functional role in mature neurons. Here, we show that Hh signaling regulates the odor response in adult Drosophila olfactory sensory neurons (OSNs). We demonstrate that this is achieved by regulating odorant receptor (OR) transport to and within the primary cilium in OSN neurons. Regulation relies on ciliary localization of the Hh signal transducer Smoothened (Smo). We further demonstrate that the Hh- and Smo-dependent regulation of the kinesin-like protein Cos2 acts in parallel to the intraflagellar transport system (IFT) to localize ORs within the cilium compartment. These findings expand our knowledge of Hh signaling to encompass chemosensory modulation and receptor trafficking.

  9. Mechanotransduction and the regulation of mTORC1 signaling in skeletal muscle.

    PubMed

    Hornberger, Troy A

    2011-09-01

    Mechanical stimuli play a major role in the regulation of skeletal muscle mass, and the maintenance of muscle mass contributes significantly to disease prevention and issues associated with the quality of life. Although the link between mechanical signals and the regulation of muscle mass has been recognized for decades, the mechanisms involved in converting mechanical information into the molecular events that control this process remain poorly defined. Nevertheless, our knowledge of these mechanisms is advancing and recent studies have revealed that signaling through a protein kinase called the mammalian target of rapamycin (mTOR) plays a central role in this event. In this review we will, (1) discuss the evidence which implicates mTOR in the mechanical regulation of skeletal muscle mass, (2) provide an overview of the mechanisms through which signaling by mTOR can be regulated, and (3) summarize our current knowledge of the potential mechanisms involved in the mechanical activation of mTOR signaling. PMID:21621634

  10. The ubiquitin–proteasome system and signal transduction pathways regulating Epithelial Mesenchymal transition of cancer

    PubMed Central

    2012-01-01

    Epithelial to Mesenchymal transition (EMT) in cancer, a process permitting cancer cells to become mobile and metastatic, has a signaling hardwire forged from development. Multiple signaling pathways that regulate carcinogenesis enabling characteristics in neoplastic cells such as proliferation, resistance to apoptosis and angiogenesis are also the main players in EMT. These pathways, as almost all cellular processes, are in their turn regulated by ubiquitination and the Ubiquitin-Proteasome System (UPS). Ubiquitination is the covalent link of target proteins with the small protein ubiquitin and serves as a signal to target protein degradation by the proteasome or to other outcomes such as endocytosis, degradation by the lysosome or specification of cellular localization. This paper reviews signal transduction pathways regulating EMT and being regulated by ubiquitination. PMID:22827778

  11. Mechanotransduction and the regulation of mTORC1 signaling in skeletal muscle.

    PubMed

    Hornberger, Troy A

    2011-09-01

    Mechanical stimuli play a major role in the regulation of skeletal muscle mass, and the maintenance of muscle mass contributes significantly to disease prevention and issues associated with the quality of life. Although the link between mechanical signals and the regulation of muscle mass has been recognized for decades, the mechanisms involved in converting mechanical information into the molecular events that control this process remain poorly defined. Nevertheless, our knowledge of these mechanisms is advancing and recent studies have revealed that signaling through a protein kinase called the mammalian target of rapamycin (mTOR) plays a central role in this event. In this review we will, (1) discuss the evidence which implicates mTOR in the mechanical regulation of skeletal muscle mass, (2) provide an overview of the mechanisms through which signaling by mTOR can be regulated, and (3) summarize our current knowledge of the potential mechanisms involved in the mechanical activation of mTOR signaling.

  12. Activation of Smurf E3 Ligase Promoted by Smoothened Regulates Hedgehog Signaling through Targeting Patched Turnover

    PubMed Central

    Zheng, Xiudeng; Chen, Zhenping; Sun, Liwei; Wang, Hailong; Zhu, Yuanxiang; Zhang, Jing; Yang, Shuyan; Lu, Yi; Sun, Qinmiao; Tao, Yi; Liu, Feng; Zhao, Yun; Chen, Dahua

    2013-01-01

    Hedgehog signaling plays conserved roles in controlling embryonic development; its dysregulation has been implicated in many human diseases including cancers. Hedgehog signaling has an unusual reception system consisting of two transmembrane proteins, Patched receptor and Smoothened signal transducer. Although activation of Smoothened and its downstream signal transduction have been intensively studied, less is known about how Patched receptor is regulated, and particularly how this regulation contributes to appropriate Hedgehog signal transduction. Here we identified a novel role of Smurf E3 ligase in regulating Hedgehog signaling by controlling Patched ubiquitination and turnover. Moreover, we showed that Smurf-mediated Patched ubiquitination depends on Smo activity in wing discs. Mechanistically, we found that Smo interacts with Smurf and promotes it to mediate Patched ubiquitination by targeting the K1261 site in Ptc. The further mathematic modeling analysis reveals that a bidirectional control of activation of Smo involving Smurf and Patched is important for signal-receiving cells to precisely interpret external signals, thereby maintaining Hedgehog signaling reliability. Finally, our data revealed an evolutionarily conserved role of Smurf proteins in controlling Hh signaling by targeting Ptc during development. PMID:24302888

  13. Glial and neuronal Semaphorin signaling instruct the development of a functional myotopic map for Drosophila walking

    PubMed Central

    Syed, Durafshan Sakeena; Gowda, Swetha B.M.; Reddy, O Venkateswara; Reichert, Heinrich; VijayRaghavan, K

    2016-01-01

    Motoneurons developmentally acquire appropriate cellular architectures that ensure connections with postsynaptic muscles and presynaptic neurons. In Drosophila, leg motoneurons are organized as a myotopic map, where their dendritic domains represent the muscle field. Here, we investigate mechanisms underlying development of aspects of this myotopic map, required for walking. A behavioral screen identified roles for Semaphorins (Sema) and Plexins (Plex) in walking behavior. Deciphering this phenotype, we show that PlexA/Sema1a mediates motoneuron axon branching in ways that differ in the proximal femur and distal tibia, based on motoneuronal birth order. Importantly, we show a novel role for glia in positioning dendrites of specific motoneurons; PlexB/Sema2a is required for dendritic positioning of late-born motoneurons but not early-born motoneurons. These findings indicate that communication within motoneurons and between glia and motoneurons, mediated by the combined action of different Plexin/Semaphorin signaling systems, are required for the formation of a functional myotopic map. DOI: http://dx.doi.org/10.7554/eLife.11572.001 PMID:26926907

  14. Participation of signaling cascades in the regulation of erythropoiesis under conditions of cytostatic treatment.

    PubMed

    Dygai, A M; Zhdanov, V V; Miroshnichenko, L A; Udut, E V; Zyuz'kov, G N; Simanina, E V; Chaikovskii, A V; Stavrova, L A; Trofimova, E S; Burmina, Ya V

    2015-01-01

    We studied the role of signaling pathways in the regulation of erythropoiesis against the background of myelosuppression caused by administration of 5-fluorouracil. The important role of cyclic AMP in the maturation of erythroid progenitors after cytostatic treatment was demonstrated. The secretory activity of myelokaryocytes during the period of erythroid hemopoiesis recovery is mainly regulated via the p38 MAPK signaling pathway; non-erythropoietin factors are involved in the formation of erythropoietic activity of adherent cells of the microenvironment.

  15. Participation of signaling cascades in the regulation of erythropoiesis under conditions of cytostatic treatment.

    PubMed

    Dygai, A M; Zhdanov, V V; Miroshnichenko, L A; Udut, E V; Zyuz'kov, G N; Simanina, E V; Chaikovskii, A V; Stavrova, L A; Trofimova, E S; Burmina, Ya V

    2015-01-01

    We studied the role of signaling pathways in the regulation of erythropoiesis against the background of myelosuppression caused by administration of 5-fluorouracil. The important role of cyclic AMP in the maturation of erythroid progenitors after cytostatic treatment was demonstrated. The secretory activity of myelokaryocytes during the period of erythroid hemopoiesis recovery is mainly regulated via the p38 MAPK signaling pathway; non-erythropoietin factors are involved in the formation of erythropoietic activity of adherent cells of the microenvironment. PMID:25578863

  16. Receptor tyrosine kinase signaling regulates replication of the peste des petits ruminants virus.

    PubMed

    Chaudhary, K; Chaubey, K K; Singh, S V; Kumar, N

    2015-03-01

    In this study, we found out that blocking the receptor tyrosine kinase (RTK) signaling in Vero cells by tryphostin AG879 impairs the in vitro replication of the peste des petits ruminants virus (PPRV). A reduced virus replication in Trk1-knockdown (siRNA) Vero cells confirmed the essential role of RTK in the virus replication, in particular a specific regulation of viral RNA synthesis. These data represent the first evidence that the RTK signaling regulates replication of a morbillivirus. PMID:25790054

  17. Leptin signaling in astrocytes regulates hypothalamic neuronal circuits and feeding.

    PubMed

    Kim, Jae Geun; Suyama, Shigetomo; Koch, Marco; Jin, Sungho; Argente-Arizon, Pilar; Argente, Jesús; Liu, Zhong-Wu; Zimmer, Marcelo R; Jeong, Jin Kwon; Szigeti-Buck, Klara; Gao, Yuanqing; Garcia-Caceres, Cristina; Yi, Chun-Xia; Salmaso, Natalina; Vaccarino, Flora M; Chowen, Julie; Diano, Sabrina; Dietrich, Marcelo O; Tschöp, Matthias H; Horvath, Tamas L

    2014-07-01

    We found that leptin receptors were expressed in hypothalamic astrocytes and that their conditional deletion led to altered glial morphology and synaptic inputs onto hypothalamic neurons involved in feeding control. Leptin-regulated feeding was diminished, whereas feeding after fasting or ghrelin administration was elevated in mice with astrocyte-specific leptin receptor deficiency. These data reveal an active role of glial cells in hypothalamic synaptic remodeling and control of feeding by leptin.

  18. Spatiotemporal regulation of early lipolytic signaling in adipocytes.

    PubMed

    Martin, Sally; Okano, Satomi; Kistler, Carol; Fernandez-Rojo, Manuel A; Hill, Michelle M; Parton, Robert G

    2009-11-13

    Hormone-sensitive lipase (HSL) is a key enzyme regulating the acute activation of lipolysis. HSL functionality is controlled by multiple phosphorylation events, which regulate its association with the surface of lipid droplets (LDs). We determined the progression and stability of HSL phosphorylation on individual serine residues both spatially and temporally in adipocytes using phospho-specific antibodies. Within seconds of beta-adrenergic receptor activation, HSL was phosphorylated on Ser-660, the phosphorylated form appearing in the peripheral cytosol prior to rapid translocation to, and stable association with, LDs. In contrast, phosphorylation of HSL on Ser-563 was delayed, the phosphorylated protein was predominantly detected on LDs, and mutation of the Ser-659/Ser-660 site to Ala significantly reduced subsequent phosphorylation on Ser-563. Phosphorylation of HSL on Ser-565 was observed in control cells; the phosphorylated protein was translocated to LDs with similar kinetics to total HSL, and the degree of phosphorylation was inversely related to phospho-HSL(Ser-563). These results describe the remarkably rapid, sequential phosphorylation of specific serine residues in HSL at spatially distinct intracellular locales, providing new insight into the complex regulation of lipolysis. PMID:19755426

  19. Reconstruction of Signaling Networks Regulating Fungal Morphogenesis by Transcriptomics▿ †

    PubMed Central

    Meyer, Vera; Arentshorst, Mark; Flitter, Simon J.; Nitsche, Benjamin M.; Kwon, Min Jin; Reynaga-Peña, Cristina G.; Bartnicki-Garcia, Salomon; van den Hondel, Cees A. M. J. J.; Ram, Arthur F. J.

    2009-01-01

    Coordinated control of hyphal elongation and branching is essential for sustaining mycelial growth of filamentous fungi. In order to study the molecular machinery ensuring polarity control in the industrial fungus Aspergillus niger, we took advantage of the temperature-sensitive (ts) apical-branching ramosa-1 mutant. We show here that this strain serves as an excellent model system to study critical steps of polar growth control during mycelial development and report for the first time a transcriptomic fingerprint of apical branching for a filamentous fungus. This fingerprint indicates that several signal transduction pathways, including TORC2, phospholipid, calcium, and cell wall integrity signaling, concertedly act to control apical branching. We furthermore identified the genetic locus affected in the ramosa-1 mutant by complementation of the ts phenotype. Sequence analyses demonstrated that a single amino acid exchange in the RmsA protein is responsible for induced apical branching of the ramosa-1 mutant. Deletion experiments showed that the corresponding rmsA gene is essential for the growth of A. niger, and complementation analyses with Saccharomyces cerevisiae evidenced that RmsA serves as a functional equivalent of the TORC2 component Avo1p. TORC2 signaling is required for actin polarization and cell wall integrity in S. cerevisiae. Congruently, our microscopic investigations showed that polarized actin organization and chitin deposition are disturbed in the ramosa-1 mutant. The integration of the transcriptomic, genetic, and phenotypic data obtained in this study allowed us to reconstruct a model for cellular events involved in apical branching. PMID:19749177

  20. Pre-LTP requires extracellular signal-regulated kinase in the ACC

    PubMed Central

    Yamanaka, Manabu; Tian, Zhen; Darvish-Ghane, Soroush

    2016-01-01

    The extracellular signal-regulated kinase is an important protein kinase for cortical plasticity. Long-term potentiation in the anterior cingulate cortex is believed to play important roles in chronic pain, fear, and anxiety. Previous studies of extracellular signal-regulated kinase are mainly focused on postsynaptic form of long-term potentiation (post-long-term potentiation). Little is known about the relationship between extracellular signal-regulated kinase and presynaptic long-term potentiation (pre-long-term potentiation) in cortical synapses. In this study, we examined whether pre-long-term potentiation in the anterior cingulate cortex requires the activation of presynaptic extracellular signal-regulated kinase. We found that p42/p44 mitogen-activated protein kinase inhibitors, PD98059 and U0126, suppressed the induction of pre-long-term potentiation. By contrast, these inhibitors did not affect the maintenance of pre-long-term potentiation. Using pharmacological inhibitors, we found that pre-long-term potentiation recorded for 1 h did not require transcriptional or translational processes. Our results strongly indicate that the activation of presynaptic extracellular signal-regulated kinase is required for the induction of pre-long-term potentiation, and this involvement may explain the contribution of extracellular signal-regulated kinase to mood disorders. PMID:27178245

  1. Intervertebral Disc Development Is Regulated by Wnt/β-catenin Signaling

    PubMed Central

    Kondo, Naoki; Yuasa, Takahito; Shimono, Kengo; Tung, Weien; Okabe, Takahiro; Yasuhara, Rika; Pacifici, Maurizio; Zhang, Yejia; Iwamoto, Masahiro; Enomoto-Iwamoto, Motomi

    2010-01-01

    Study Design Histological analysis of intervertebral disc (IVD) in three types of transgenic mice. Objectives To investigate the role of Wnt/β-catenin signaling in regulation of IVD development and organization. Summary of Background Data β-catenin dependent Wnt signaling is one of the central regulators in cartilage development during limb skeletal formation. Little is known, however, about the physiological relevance of this signaling pathway to IVD development and organization. Methods Temporal-spatial distribution of Wnt/β-catenin signaling activity was examined in IVD using Wnt/β-catenin reporter (TOPGAL) mice. The structural changes in the mouse IVD components such as the nucleus pulposus (NP), endplate (EP), annulus fibrosus (AF), and the growth plate (GP) of the vertebral body were analyzed following transient activation of Wnt/β-catenin signaling or deletion of β-catenin in the mice. Results Activity of Wnt/β-catenin signaling was high in EP, AF and GP in the embryonic stages and decreased at the postnatal stage; it was undetectable in the embryonic NP but up-regulated after birth. The transient activation of Wnt/β-catenin signaling caused severe deterioration of the GP and the AF, whereas deficiency of β-catenin accelerated bone formation in between EP and GP. Conclusion The findings in this study suggest that proper regulation of Wnt/β-catenin signaling is required for development and organization of IVD. PMID:21270710

  2. Bone morphogenetic protein (BMP) signaling regulates mitotic checkpoint protein levels in human breast cancer cells.

    PubMed

    Yan, Hualong; Zhu, Songcheng; Song, Chenlin; Liu, Naifa; Kang, Jiuhong

    2012-04-01

    Aberrant expression of mitotic checkpoint genes compromises mitotic checkpoint, leads to chromosome instability and tumorigenesis. However, the cell signals that control mitotic checkpoint gene expression have not been reported so far. In the present study we show that, in human breast cancer cells, chemical inhibition of Bone morphogenetic proteins (BMPs), but not Transforming Growth Factor-β (TGF-β), abrogates the mitotic arrest induced by nocodazole. Protein expression analysis reveals that inhibition of BMP signaling dramatically down regulates protein levels of mitotic checkpoint components BUB3, Hec1, TTK and MAD2, but inhibition of TGF-β has relatively minor effect on the expression of these proteins. Activation of BMP signaling specifically up regulates BUB3, and activation of Activin A signaling globally down regulates these proteins level. Furthermore, overexpressing MAD2, TTK, BUB3 or Hec1 significantly rescues the mitotic arrest defect caused by BMP inhibition. Our results demonstrated for the first time that TGF-β family cytokines are cellular signals regulating mitotic checkpoint and perturbations in intrinsic BMP signaling could lead to suppression of mitotic checkpoint signaling by downregulating key checkpoint proteins. The results suggest a possible mechanism by which dysregulation of TGF-β signaling causes mitotic checkpoint defects and drives tumorigenesis. The finding also provides a potential and more specific strategy for cancer prevention by targeting BMP and mitotic checkpoint connection. PMID:22234345

  3. Characterization and Regulation of Suppressor of Cytokine Signaling (SOCS) Genes in Yellow Perch (Perca flavescens)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The suppressor of cytokine signaling (SOCS) proteins are a family of intracellular proteins that are centrally involved with vertebrate growth, development, and immunity via their effects as negative feedback regulators of cytokine (and hormone) signaling. A number of SOCS genes have been recently ...

  4. Lymphotoxin signals from positively selected thymocytes regulate the terminal differentiation of medullary thymic epithelial cells.

    PubMed

    White, Andrea J; Nakamura, Kyoko; Jenkinson, William E; Saini, Manoj; Sinclair, Charles; Seddon, Benedict; Narendran, Parth; Pfeffer, Klaus; Nitta, Takeshi; Takahama, Yousuke; Caamano, Jorge H; Lane, Peter J L; Jenkinson, Eric J; Anderson, Graham

    2010-10-15

    The thymic medulla represents a key site for the induction of T cell tolerance. In particular, autoimmune regulator (Aire)-expressing medullary thymic epithelial cells (mTECs) provide a spectrum of tissue-restricted Ags that, through both direct presentation and cross-presentation by dendritic cells, purge the developing T cell repertoire of autoimmune specificities. Despite this role, the mechanisms of Aire(+) mTEC development remain unclear, particularly those stages that occur post-Aire expression and represent mTEC terminal differentiation. In this study, in mouse thymus, we analyze late-stage mTEC development in relation to the timing and requirements for Aire and involucrin expression, the latter a marker of terminally differentiated epithelium including Hassall's corpuscles. We show that Aire expression and terminal differentiation within the mTEC lineage are temporally separable events that are controlled by distinct mechanisms. We find that whereas mature thymocytes are not essential for Aire(+) mTEC development, use of an inducible ZAP70 transgenic mouse line--in which positive selection can be temporally controlled--demonstrates that the emergence of involucrin(+) mTECs critically depends upon the presence of mature single positive thymocytes. Finally, although initial formation of Aire(+) mTECs depends upon RANK signaling, continued mTEC development to the involucrin(+) stage maps to activation of the LTα-LTβR axis by mature thymocytes. Collectively, our results reveal further complexity in the mechanisms regulating thymus medulla development and highlight the role of distinct TNFRs in initial and terminal differentiation stages in mTECs.

  5. Notch signaling controls chondrocyte hypertrophy via indirect regulation of Sox9

    PubMed Central

    Kohn, Anat; Rutkowski, Timothy P; Liu, Zhaoyang; Mirando, Anthony J; Zuscik, Michael J; O’Keefe, Regis J; Hilton, Matthew J

    2015-01-01

    RBPjk-dependent Notch signaling regulates both the onset of chondrocyte hypertrophy and the progression to terminal chondrocyte maturation during endochondral ossification. It has been suggested that Notch signaling can regulate Sox9 transcription, although how this occurs at the molecular level in chondrocytes and whether this transcriptional regulation mediates Notch control of chondrocyte hypertrophy and cartilage development is unknown or controversial. Here we have provided conclusive genetic evidence linking RBPjk-dependent Notch signaling to the regulation of Sox9 expression and chondrocyte hypertrophy by examining tissue-specific Rbpjk mutant (Prx1Cre;Rbpjkf/f), Rbpjk mutant/Sox9 haploinsufficient (Prx1Cre;Rbpjkf/f;Sox9f/+), and control embryos for alterations in SOX9 expression and chondrocyte hypertrophy during cartilage development. These studies demonstrate that Notch signaling regulates the onset of chondrocyte maturation in a SOX9-dependent manner, while Notch-mediated regulation of terminal chondrocyte maturation likely functions independently of SOX9. Furthermore, our in vitro molecular analyses of the Sox9 promoter and Notch-mediated regulation of Sox9 gene expression in chondrogenic cells identified the ability of Notch to induce Sox9 expression directly in the acute setting, but suppresses Sox9 transcription with prolonged Notch signaling that requires protein synthesis of secondary effectors. PMID:26558140

  6. Mapping sea ice using reflected GNSS signals in a bistatic radar system

    NASA Astrophysics Data System (ADS)

    Chew, Clara; Zuffada, Cinzia; Shah, Rashmi; Mannucci, Anthony

    2016-04-01

    Global Navigation Satellite System (GNSS) signals can be used as a kind of bistatic radar, with receivers opportunistically recording ground-reflected signals transmitted by the GNSS satellites themselves. This technique, GNSS-Reflectometry (GNSS-R), has primarily been explored using receivers flown on aircraft or balloons, or in modeling studies. Last year's launch of the TechDemoSat-1 (TDS-1) satellite represents an enormous opportunity to investigate the potential of using spaceborne GNSS receivers to sense changes in the land and ocean surface. Here, we examine the ability of reflected GNSS signals to estimate sea ice extent and sea ice age, as well as comment on the possibility of using GNSS-R to detect leads and polynyas within the ice. In particular, we quantify how the peak power of Delay Doppler Maps (DDMs) generated within the GNSS receiver responds as the satellite flies over the Polar Regions. To compute the effective peak power of each DDM, we first normalize the peak power of the DDM by the noise floor. We also correct for antenna gain, range, and incidence angle. Once these corrections are made, the effective peak power across DDMs may be used as a proxy for changes in surface permittivity and surface roughness. We compare our calculations of reflected power to existing sea ice remote sensing products such as data from the SSMI/S as well as Landsat imagery. Our analysis shows that GNSS reflections are extremely sensitive to the sea ice edge, with increases in reflected power of more than 10 dB relative to reflected power over the open ocean. As the sea ice ages, it thickens and roughens, and reflected power decreases, though it does not decrease below the power over the open ocean. Given the observed sensitivity of GNSS reflections to small features over land and the sensitivity to the sea ice edge, we hypothesize that reflection data could help map the temporal evolution of leads and polynyas.

  7. Zfp423 Regulates Sonic Hedgehog Signaling via Primary Cilium Function

    PubMed Central

    Hamilton, Bruce A.

    2016-01-01

    Zfp423 encodes a 30-zinc finger transcription factor that intersects several canonical signaling pathways. Zfp423 mutations result in ciliopathy-related phenotypes, including agenesis of the cerebellar vermis in mice and Joubert syndrome (JBTS19) and nephronophthisis (NPHP14) in humans. Unlike most ciliopathy genes, Zfp423 encodes a nuclear protein and its developmental expression is complex, leading to alternative proposals for cellular mechanisms. Here we show that Zfp423 is expressed by cerebellar granule cell precursors, that loss of Zfp423 in these precursors leads to cell-intrinsic reduction in proliferation, loss of response to Shh, and primary cilia abnormalities that include diminished frequency of both Smoothened and IFT88 localization. Loss of Zfp423 alters expression of several genes encoding key cilium components, including increased expression of Tulp3. Tulp3 is a direct binding target of Zfp423 and reducing the overexpression of Tulp3 in Zfp423-deficient cells suppresses Smoothened translocation defects. These results define Zfp423 deficiency as a bona fide ciliopathy, acting upstream of Shh signaling, and indicate a mechanism intrinsic to granule cell precursors for the resulting cerebellar hypoplasia. PMID:27727273

  8. Regulation of amyloid precursor protein processing by serotonin signaling.

    PubMed

    Pimenova, Anna A; Thathiah, Amantha; De Strooper, Bart; Tesseur, Ina

    2014-01-01

    Proteolytic processing of the amyloid precursor protein (APP) by the β- and γ-secretases releases the amyloid-β peptide (Aβ), which deposits in senile plaques and contributes to the etiology of Alzheimer's disease (AD). The α-secretase cleaves APP in the Aβ peptide sequence to generate soluble APPα (sAPPα). Upregulation of α-secretase activity through the 5-hydroxytryptamine 4 (5-HT4) receptor has been shown to reduce Aβ production, amyloid plaque load and to improve cognitive impairment in transgenic mouse models of AD. Consequently, activation of 5-HT4 receptors following agonist stimulation is considered to be a therapeutic strategy for AD treatment; however, the signaling cascade involved in 5-HT4 receptor-stimulated proteolysis of APP remains to be determined. Here we used chemical and siRNA inhibition to identify the proteins which mediate 5-HT4d receptor-stimulated α-secretase activity in the SH-SY5Y human neuronal cell line. We show that G protein and Src dependent activation of phospholipase C are required for α-secretase activity, while, unexpectedly, adenylyl cyclase and cAMP are not involved. Further elucidation of the signaling pathway indicates that inositol triphosphate phosphorylation and casein kinase 2 activation is also a prerequisite for α-secretase activity. Our findings provide a novel route to explore the treatment of AD through 5-HT4 receptor-induced α-secretase activation.

  9. Erythropoietin regulates Treg cells in asthma through TGFβ receptor signaling.

    PubMed

    Wan, Guoshi; Wei, Bing

    2015-01-01

    Asthma is a chronic inflammatory disorder of the airways, the development of which is suppressed by regulatory T cells (Treg). Erythropoietin (EPO) is originally defined as a hematopoietic growth factor. Recently, the anti-inflammatory effects of EPO in asthma have been acknowledged. However, the underlying mechanisms remain ill-defined. Here, we showed that EPO treatment significantly reduced the severity of an ovalbumin (OVA)-induced asthma in mice, seemingly through promoting Foxp3-mediated activation of Treg cells in OVA-treated mouse lung. The activation of Treg cells resulted from increases in transforming growth factor β1 (TGFβ1), which were mainly produced by M2 macrophages (M2M). In vitro, Co-culture with M2M increased Foxp3 levels in Treg cells and the Treg cell number, in a TGFβ receptor signaling dependent manner. Moreover, elimination of macrophages abolished the therapeutic effects of EPO in vivo. Together, our data suggest that EPO may increase M2M, which activate Treg cells through TGFβ receptor signaling to mitigate the severity of asthma.

  10. Erythropoietin regulates Treg cells in asthma through TGFβ receptor signaling

    PubMed Central

    Wan, Guoshi; Wei, Bing

    2015-01-01

    Asthma is a chronic inflammatory disorder of the airways, the development of which is suppressed by regulatory T cells (Treg). Erythropoietin (EPO) is originally defined as a hematopoietic growth factor. Recently, the anti-inflammatory effects of EPO in asthma have been acknowledged. However, the underlying mechanisms remain ill-defined. Here, we showed that EPO treatment significantly reduced the severity of an ovalbumin (OVA)-induced asthma in mice, seemingly through promoting Foxp3-mediated activation of Treg cells in OVA-treated mouse lung. The activation of Treg cells resulted from increases in transforming growth factor β1 (TGFβ1), which were mainly produced by M2 macrophages (M2M). In vitro, Co-culture with M2M increased Foxp3 levels in Treg cells and the Treg cell number, in a TGFβ receptor signaling dependent manner. Moreover, elimination of macrophages abolished the therapeutic effects of EPO in vivo. Together, our data suggest that EPO may increase M2M, which activate Treg cells through TGFβ receptor signaling to mitigate the severity of asthma. PMID:26807178

  11. Purinergic regulation of vascular endothelial growth factor signaling in angiogenesis

    PubMed Central

    Rumjahn, S M; Yokdang, N; Baldwin, K A; Thai, J; Buxton, I L O

    2009-01-01

    P2Y purine nucleotide receptors (P2YRs) promote endothelial cell tubulogenesis through breast cancer cell-secreted nucleoside diphosphate kinase (NDPK). We tested the hypothesis that activated P2Y1 receptors transactivate vascular endothelial growth factor receptor (VEGFR-2) in angiogenic signaling. P2Y1R stimulation (10 μM 2-methyl-thio-ATP (2MS-ATP)) of angiogenesis is suppressed by the VEGFR-2 tyrosine kinase inhibitor, SU1498 (1 μM). Phosphorylation of VEGFR-2 by 0.0262 or 2.62 nM VEGF was comparable with 0.01 or 10 μM 2MS-ATP stimulation of the P2Y1R. 2MS-ATP, and VEGF stimulation increased tyrosine phosphorylation at tyr1175. 2MS-ATP (0.1–10 μM) also stimulated EC tubulogenesis in a dose-dependent manner. The addition of sub-maximal VEGF (70 pM) in the presence of increasing concentrations of 2MS-ATP yielded additive effects at 2MS-ATP concentrations <3 μM, whereas producing saturated and less than additive effects at ⩾3 μM. We propose that the VEGF receptor can be activated in the absence of VEGF, and that the P2YR–VEGFR2 interaction and resulting signal transduction is a critical determinant of vascular homoeostasis and tumour-mediated angiogenesis. PMID:19367276

  12. Regulation of amyloid precursor protein processing by serotonin signaling.

    PubMed

    Pimenova, Anna A; Thathiah, Amantha; De Strooper, Bart; Tesseur, Ina

    2014-01-01

    Proteolytic processing of the amyloid precursor protein (APP) by the β- and γ-secretases releases the amyloid-β peptide (Aβ), which deposits in senile plaques and contributes to the etiology of Alzheimer's disease (AD). The α-secretase cleaves APP in the Aβ peptide sequence to generate soluble APPα (sAPPα). Upregulation of α-secretase activity through the 5-hydroxytryptamine 4 (5-HT4) receptor has been shown to reduce Aβ production, amyloid plaque load and to improve cognitive impairment in transgenic mouse models of AD. Consequently, activation of 5-HT4 receptors following agonist stimulation is considered to be a therapeutic strategy for AD treatment; however, the signaling cascade involved in 5-HT4 receptor-stimulated proteolysis of APP remains to be determined. Here we used chemical and siRNA inhibition to identify the proteins which mediate 5-HT4d receptor-stimulated α-secretase activity in the SH-SY5Y human neuronal cell line. We show that G protein and Src dependent activation of phospholipase C are required for α-secretase activity, while, unexpectedly, adenylyl cyclase and cAMP are not involved. Further elucidation of the signaling pathway indicates that inositol triphosphate phosphorylation and casein kinase 2 activation is also a prerequisite for α-secretase activity. Our findings provide a novel route to explore the treatment of AD through 5-HT4 receptor-induced α-secretase activation. PMID:24466315

  13. Mapping Transient Hyperventilation Induced Alterations with Estimates of the Multi-Scale Dynamics of BOLD Signal

    PubMed Central

    Kiviniemi, Vesa; Remes, Jukka; Starck, Tuomo; Nikkinen, Juha; Haapea, Marianne; Silven, Olli; Tervonen, Osmo

    2009-01-01

    Temporal blood oxygen level dependent (BOLD) contrast signals in functional MRI during rest may be characterized by power spectral distribution (PSD) trends of the form 1/fα. Trends with 1/f characteristics comprise fractal properties with repeating oscillation patterns in multiple time scales. Estimates of the fractal properties enable the quantification of phenomena that may otherwise be difficult to measure, such as transient, non-linear changes. In this study it was hypothesized that the fractal metrics of 1/f BOLD signal trends can map changes related to dynamic, multi-scale alterations in cerebral blood flow (CBF) after a transient hyperventilation challenge. Twenty-three normal adults were imaged in a resting-state before and after hyperventilation. Different variables (1/f trend constant α, fractal dimension Df, and, Hurst exponent H) characterizing the trends were measured from BOLD signals. The results show that fractal metrics of the BOLD signal follow the fractional Gaussian noise model, even during the dynamic CBF change that follows hyperventilation. The most dominant effect on the fractal metrics was detected in grey matter, in line with previous hyperventilation vaso-reactivity studies. The α was able to differentiate also blood vessels from grey matter changes. Df was most sensitive to grey matter. H correlated with default mode network areas before hyperventilation but this pattern vanished after hyperventilation due to a global increase in H. In the future, resting-state fMRI combined with fractal metrics of the BOLD signal may be used for analyzing multi-scale alterations of cerebral blood flow. PMID:19636388

  14. Structural evidence for cooperative microtubule stabilization by Taxol and the endogenous dynamics regulator MAP4

    PubMed Central

    Xiao, Hui; Wang, Hui; Zhang, Xuechun; Tu, Zongcai; Bulinski, Chloë; Khrapunovich-Baine, Marina; Angeletti, Ruth Hogue; Horwitz, Susan Band

    2012-01-01

    Microtubules (MTs) composed of αβ-tubulin heterodimers are highly dynamic polymers, whose stability can be regulated by numerous endogenous and exogenous factors. Both the anti-mitotic drug, Taxol, and microtubule-associated proteins (MAPs) stabilize this dynamicity by binding to and altering the conformation of MTs. In the current study, amide hydrogen/deuterium exchange coupled with mass spectrometry (HDX-MS) was used to examine the structural and dynamic properties of the MT complex with the microtubule binding domain of MAP4 (MTB-MAP4) in the presence and absence of Taxol. The changes in the HDX levels indicate that MTB-MAP4 may bind to both the outside and the luminal surfaces of the MTs, and that Taxol reduces both of these interactions. The MTB-MAP4 binding induces conformational rearrangements of α- and β-tubulin that promote an overall stabilization of MTs. Paradoxically, despite Taxol’s negative effects on MAP4 interactions with the MTs, its binding to the MTB-MAP4-MT complex further reduces the overall deuterium incorporation, suggesting that a more stable complex is formed in the presence of the drug. PMID:22270553

  15. Regulation of Caenorhabditis elegans p53/CEP-1–Dependent Germ Cell Apoptosis by Ras/MAPK Signaling

    PubMed Central

    Rutkowski, Rachael; Dickinson, Robin; Stewart, Graeme; Craig, Ashley; Schimpl, Marianne; Keyse, Stephen M.; Gartner, Anton

    2011-01-01

    Maintaining genome stability in the germline is thought to be an evolutionarily ancient role of the p53 family. The sole Caenorhabditis elegans p53 family member CEP-1 is required for apoptosis induction in meiotic, late-stage pachytene germ cells in response to DNA damage and meiotic recombination failure. In an unbiased genetic screen for negative regulators of CEP-1, we found that increased activation of the C. elegans ERK orthologue MPK-1, resulting from either loss of the lip-1 phosphatase or activation of let-60 Ras, results in enhanced cep-1–dependent DNA damage induced apoptosis. We further show that MPK-1 is required for DNA damage–induced germ cell apoptosis. We provide evidence that MPK-1 signaling regulates the apoptotic competency of germ cells by restricting CEP-1 protein expression to cells in late pachytene. Restricting CEP-1 expression to cells in late pachytene is thought to ensure that apoptosis doesn't occur in earlier-stage cells where meiotic recombination occurs. MPK-1 signaling regulates CEP-1 expression in part by regulating the levels of GLD-1, a translational repressor of CEP-1, but also via a GLD-1–independent mechanism. In addition, we show that MPK-1 is phosphorylated and activated upon ionising radiation (IR) in late pachytene germ cells and that MPK-1–dependent CEP-1 activation may be in part direct, as these two proteins interact in a yeast two-hybrid assay. In summary, we report our novel finding that MAP kinase signaling controls CEP-1–dependent apoptosis by several different pathways that converge on CEP-1. Since apoptosis is also restricted to pachytene stage cells in mammalian germlines, analogous mechanisms regulating p53 family members are likely to be conserved throughout evolution. PMID:21901106

  16. Negative regulation of RIG-I-mediated antiviral signaling by TRK-fused gene (TFG) protein

    SciTech Connect

    Lee, Na-Rae; Shin, Han-Bo; Kim, Hye-In; Choi, Myung-Soo; Inn, Kyung-Soo

    2013-07-19

    Highlights: •TRK-fused gene product (TFG) interacts with TRIM25 upon viral infection. •TFG negatively regulates RIG-I mediated antiviral signaling. •TFG depletion leads to enhanced viral replication. •TFG act downstream of MAVS. -- Abstract: RIG-I (retinoic acid inducible gene I)-mediated antiviral signaling serves as the first line of defense against viral infection. Upon detection of viral RNA, RIG-I undergoes TRIM25 (tripartite motif protein 25)-mediated K63-linked ubiquitination, leading to type I interferon (IFN) production. In this study, we demonstrate that TRK-fused gene (TFG) protein, previously identified as a TRIM25-interacting protein, binds TRIM25 upon virus infection and negatively regulates RIG-I-mediated type-I IFN signaling. RIG-I-mediated IFN production and nuclear factor (NF)-κB signaling pathways were upregulated by the suppression of TFG expression. Furthermore, vesicular stomatitis virus (VSV) replication was significantly inhibited by small inhibitory hairpin RNA (shRNA)-mediated knockdown of TFG, supporting the suppressive role of TFG in RIG-I-mediated antiviral signaling. Interestingly, suppression of TFG expression increased not only RIG-I-mediated signaling but also MAVS (mitochondrial antiviral signaling protein)-induced signaling, suggesting that TFG plays a pivotal role in negative regulation of RNA-sensing, RIG-I-like receptor (RLR) family signaling pathways.

  17. Domain Specificity of MAP3K Family Members, MLK and Tak1, for JNK Signaling in Drosophila

    PubMed Central

    Stronach, Beth; Lennox, Ashley L.; Garlena, Rebecca A.

    2014-01-01

    A highly diverse set of protein kinases functions as early responders in the mitogen- and stress-activated protein kinase (MAPK/SAPK) signaling pathways. For instance, humans possess 14 MAPK kinase kinases (MAP3Ks) that activate Jun kinase (JNK) signaling downstream. A major challenge is to decipher the selective and redundant functions of these upstream MAP3Ks. Taking advantage of the relative simplicity of Drosophila melanogaster as a model system, we assessed MAP3K signaling specificity in several JNK-dependent processes during development and stress response. Our approach was to generate molecular chimeras between two MAP3K family members, the mixed lineage kinase, Slpr, and the TGF-β activated kinase, Tak1, which share 32% amino acid identity across the kinase domain but otherwise differ in sequence and domain structure, and then test the contributions of various domains for protein localization, complementation of mutants, and activation of signaling. We found that overexpression of the wild-type kinases stimulated JNK signaling in alternate contexts, so cells were capable of responding to both MAP3Ks, but with distinct outcomes. Relative to wild-type, the catalytic domain swaps compensated weakly or not at all, despite having a shared substrate, the JNK kinase Hep. Tak1 C-terminal domain-containing constructs were inhibitory in Tak1 signaling contexts, including tumor necrosis factor-dependent cell death and innate immune signaling; however, depressing antimicrobial gene expression did not necessarily cause phenotypic susceptibility to infection. These same constructs were neutral in the context of Slpr-dependent developmental signaling, reflecting differential subcellular protein localization and by inference, point of activation. Altogether, our findings suggest that the selective deployment of a particular MAP3K can be attributed in part to its inherent sequence differences, cellular localization, and binding partner availability. PMID:24429281

  18. Brassinosteroid regulated kinases (BRKs) that mediate brassinosteroid signal transduction and uses thereof

    DOEpatents

    Wang, Zhi-Yong; Tang, Wenqiang

    2013-09-24

    The present invention identifies a novel family of kinases regulated by brassinosteroids, referred to as BRKs (brassinosteroid regulated kinases) or BSKs (brassinosteroid signaling kinases). The present invention provides methods for modulating the response of a plant cell to a brassinosteroid using BRKs.

  19. Peroxiredoxins in Regulation of MAPK Signalling Pathways; Sensors and Barriers to Signal Transduction

    PubMed Central

    Latimer, Heather R.; Veal, Elizabeth A.

    2016-01-01

    Peroxiredoxins are highly conserved and abundant peroxidases. Although the thioredoxin peroxidase activity of peroxiredoxin (Prx) is important to maintain low levels of endogenous hydrogen peroxide, Prx have also been shown to promote hydrogen peroxide-mediated signalling. Mitogen activated protein kinase (MAPK) signalling pathways mediate cellular responses to a variety of stimuli, including reactive oxygen species (ROS). Here we review the evidence that Prx can act as both sensors and barriers to the activation of MAPK and discuss the underlying mechanisms involved, focusing in particular on the relationship with thioredoxin. PMID:26813660

  20. Reciprocal Regulation of AKT and MAP Kinase Dictates Virus-Host Cell Fusion ▿

    PubMed Central

    Sharma, Nishi R.; Mani, Prashant; Nandwani, Neha; Mishra, Rajakishore; Rana, Ajay; Sarkar, Debi P.

    2010-01-01

    Viruses of the Paramyxoviridae family bind to their host cells by using hemagglutinin-neuraminidase (HN), which enhances fusion protein (F)-mediated membrane fusion. Although respiratory syncytial virus and parainfluenza virus 5 of this family are suggested to trigger host cell signaling during infection, the virus-induced intracellular signals dictating virus-cell fusion await elucidation. Using an F- or HN-F-containing reconstituted envelope of Sendai virus, another paramyxovirus, we revealed the role and regulation of AKT1 and Raf/MEK/ERK cascades during viral fusion with liver cells. Our observation that extracellular signal-regulated kinase (ERK) activation promotes viral fusion via ezrin-mediated cytoskeletal rearrangements, whereas AKT1 attenuates fusion by promoting phosphorylation of F protein, indicates a counteractive regulation of viral fusion by reciprocal activation of AKT1 and mitogen-activated protein kinase (MAPK) cascades, establishing a novel conceptual framework for a therapeutic strategy. PMID:20164223

  1. The Shc locus regulates insulin signaling and adiposity in mammals

    PubMed Central

    Tomilov, Alexey A.; Ramsey, Jon J.; Hagopian, Kevork; Giorgio, Marco; Kim, Kyoungmi M.; Lam, Adam; Migliaccio, Enrica; Lloyd, Kent C.; Berniakovich, Ina; Prolla, Tomas A.; Pelicci, PierGiuseppe; Cortopassi, Gino A.

    2014-01-01

    Summary Longevity of a p66Shc knockout strain (ShcP) was previously attributed to increased stress resistance and altered mitochondria. Microarrays of ShcP tissues indicated alterations in insulin signaling. Consistent with this observation, ShcP mice were more insulin sensitive and glucose tolerant at organismal and tissue levels, as was a novel p66Shc knockout (ShcL). Increasing and decreasing Shc expression in cell lines decreased and increased insulin sensitivity, respectively – consistent with p66Shc's function as a repressor of insulin signaling. However, differences between the two p66Shc knockout strains were also observed. ShcL mice were fatter and susceptible to fatty diets, and their fat was more insulin sensitive than controls. On the other hand, ShcP mice were leaner and resisted fatty diets, and their adipose was less insulin sensitive than controls. ShcL and ShcP strains are both highly inbred on the C57Bl/6 background, so we investigated gene expression at the Shc locus, which encodes three isoforms, p66, p52, and p46. Isoform p66 is absent in both strains; thus, the remaining difference to which to attribute the ‘lean’ phenotype is expression of the other two isoforms. ShcL mice have a precise deletion of p66Shc and normal expression of p52 and p46Shc isoforms in all tissues; thus, a simple deletion of p66Shc results in a ‘fat’ phenotype. However, ShcP mice in addition to p66Shc deletion have a fourfold increase in p46Shc expression in white fat. Thus, p46Shc overexpression in fat, rather than p66Shc deletion, is the likely cause of decreased adiposity and reduced insulin sensitivity in the fat of ShcP mice, which has implications for the longevity of the strain. PMID:21040401

  2. Dopamine signaling regulates the projection patterns in the mouse chiasm.

    PubMed

    Chen, Tingting; Hu, Yunlong; Lin, Xiaotan; Huang, Xinping; Liu, Bin; Leung, Peggy; Chan, Sun-On; Guo, Deyin; Jin, Guangyi

    2015-11-01

    Ocular albinism (OA) is characterized by inadequate L-3, 4-dihydroxyphenylalanine (L-DOPA) and dopamine (DA) in the eyes. This study investigated DA-related signaling pathways in mouse chiasm projection patterns and the potential role of ocular albinism type 1 (OA1) and dopamine 1A (D1A) receptors in the optic pathway. In embryonic day (E) E13-E15 retina, most L-DOPA and OA1-positive cells were distributed among Müller glial cells on E13 and retinal ganglion cells (RGC) on E14. In the ventral diencephalon, OA1 and L-DOPA were strongly expressed on the optic chiasm (OC) and optic tract (OT), respectively, but weak on the optic stalk (OS). At E13-E15, DA and D1A staining was predominately expressed in radially arranged cells with a neuronal expression pattern. In the ventral diencephalon, DA and D1A were strongly expressed on the OC, OT and OS. Furthermore, L-DOPA significantly inhibited retinal axon outgrowth in both the dorsal nasal (DN) and ventral temporal (VT) groups. DA inhibited retinal axon outgrowth, which was abolished by the D1A antagonist SCH23390. Brain slice cultures indicated that L-DOPA inhibited axons that crossed at the OC of E13 embryos, which was not abolished by DA. L-DOPA also inhibited axons that crossed at the OC of albino mice. Albino mice exhibited reduced ipsilateral retinal projections compared with C57 pigmented mice. No significant difference was identified in the uncrossed projections of albino mice following L-DOPA and DA expression. Furthermore, transcription factor Zic family member 2 (Zic2) upregulated OA1 mRNA expression. Our findings provide critical insights into DA-related signaling in retinal development. PMID:26363092

  3. Signal transduction pathways that regulate CAB gene expression. Progress report

    SciTech Connect

    Chory, J.

    1993-12-31

    We have completed the initial genetic and phenotypic characterization of several classes of new mutants that affect CAB gene expression. The doc mutants (for dark overexpression of cab) are characterized by elevated levels of CAB gene expression in the dark; however, unlike the previously isolated de-etiolated mutants (also isolated in my lab), the doc mutants still appear etiolated. The doc alleles define 3 loci, each of which maps to a separate chromosome. The details of the mutant isolation scheme and the genetic and phenotypic description of these new mutants are described. The second class of mutants, the gun mutants (for genomes uncoupled) show accumulation of CAB mRNA in the absence of chloroplast gene expression and development. Thus, the normally tightly coordinated expression between the chloroplast and nuclear genes that encode chloroplast-destined proteins has been uncoupled. We have shown that the Arabidopsis HY3 locus encodes the type B phytochrome apoprotein gene and have characterized the phenotypes of null hy3 alleles to ascertain a role for this phytochrome in Arabidopsis development. We have also isolated and characterized a number of alleles of the phytochrome A gene.

  4. The cold response of CBF genes in barley is regulated by distinct signaling mechanisms.

    PubMed

    Marozsán-Tóth, Zsuzsa; Vashegyi, Ildikó; Galiba, Gábor; Tóth, Balázs

    2015-06-01

    Cold acclimation ability is crucial in the winter survival of cereals. In this process CBF transcription factors play key role, therefore understanding the regulation of these genes might provide useful knowledge for molecular breeding. In the present study the signal transduction pathways leading to the cold induction of different CBF genes were investigated in barley cv. Nure using pharmacological approach. Our results showed that the cold induced expression of CBF9 and CBF14 transcription factors is regulated by phospholipase C, phospholipase D pathways and calcium. On the contrary, these pathways have negative effect on the cold induction of CBF12 that is regulated by a different, as yet unidentified pathway. The diversity in the regulation of these transcription factors corresponds to their sequence based phylogenetic relationships suggesting that their evolutionary separation happened on structural, functional and regulational levels as well. On the CBF effector gene level, the signaling regulation is more complex, resultant effect of multiple pathways.

  5. Gliolectin positively regulates Notch signalling during wing-vein specification in Drosophila.

    PubMed

    Prasad, Naveen; Shashidhara, Lingadahalli S

    2015-01-01

    Notch signalling is essential for animal development. It integrates multiple pathways controlling cell fate and specification. Here we report the genetic characterization of Gliolectin, presumably a lectin, a cytoplasmic protein, significantly enriched in Golgi bodies. Its expression overlaps with regions where Notch is activated. Loss of gliolectin function results in ectopic veins, while gain of its function causes loss of wing veins. It positively regulates Enhancer of split mβ, a target of Notch signalling. These observations suggest that it is a positive regulator of Notch signalling during wing development in Drosophila. PMID:26505251

  6. Regulation and function of syk tyrosine kinase in mast cell signaling and beyond.

    PubMed

    de Castro, Rodrigo Orlandini

    2011-01-01

    The protein tyrosine kinase Syk plays a critical role in FcεRI signaling in mast cells. Binding of Syk to phosphorylated immunoreceptor tyrosine-based activation motifs (p-ITAM) of the receptor subunits results in conformational changes and tyrosine phosphorylation at multiple sites that leads to activation of Syk. The phosphorylated tyrosines throughout the molecule play an important role in the regulation of Syk-mediated signaling. Reconstitution of receptor-mediated signaling in Syk(-/-) cells by wild-type Syk or mutants which have substitution of these tyrosines with phenylalanine together with in vitro assays has been useful strategies to understand the regulation and function of Syk.

  7. Post-transcriptional regulation of ethylene perception and signaling in Arabidopsis

    SciTech Connect

    Schaller, George Eric

    2014-03-19

    The simple gas ethylene functions as an endogenous regulator of plant growth and development, and modulates such energy relevant processes as photosynthesis and biomass accumulation. Ethylene is perceived in the plant Arabidopsis by a five-member family of receptors related to bacterial histidine kinases. Our data support a general model in which the receptors exist as parts of larger protein complexes. Our goals have been to (1) characterize physical interactions among members of the signaling complex; (2) the role of histidine-kinase transphosphorylation in signaling by the complex; and (3) the role of a novel family of proteins that regulate signal output by the receptors.

  8. Autocrine signaling involved in cell volume regulation: the role of released transmitters and plasma membrane receptors.

    PubMed

    Franco, Rodrigo; Panayiotidis, Mihalis I; de la Paz, Lenin D Ochoa

    2008-07-01

    Cell volume regulation is a basic homeostatic mechanism transcendental for the normal physiology and function of cells. It is mediated principally by the activation of osmolyte transport pathways that result in net changes in solute concentration that counteract cell volume challenges in its constancy. This process has been described to be regulated by a complex assortment of intracellular signal transduction cascades. Recently, several studies have demonstrated that alterations in cell volume induce the release of a wide variety of transmitters including hormones, ATP and neurotransmitters, which have been proposed to act as extracellular signals that regulate the activation of cell volume regulatory mechanisms. In addition, changes in cell volume have also been reported to activate plasma membrane receptors (including tyrosine kinase receptors, G-protein coupled receptors and integrins) that have been demonstrated to participate in the regulatory process of cell volume. In this review, we summarize recent studies about the role of changes in cell volume in the regulation of transmitter release as well as in the activation of plasma membrane receptors and their further implications in the regulation of the signaling machinery that regulates the activation of osmolyte flux pathways. We propose that the autocrine regulation of Ca2+-dependent and tyrosine phosphorylation-dependent signaling pathways by the activation of plasma membrane receptors and swelling-induced transmitter release is necessary for the activation/regulation of osmolyte efflux pathways and cell volume recovery. Furthermore, we emphasize the importance of studying these extrinsic signals because of their significance in the understanding of the physiology of cell volume regulation and its role in cell biology in vivo, where the constraint of the extracellular space might enhance the autocrine or even paracrine signaling induced by these released transmitters. PMID:18300263

  9. Bidirectional regulation of the cAMP response element binding protein encodes spatial map alignment in prism-adapting barn owls.

    PubMed

    Nichols, Grant S; DeBello, William M

    2008-10-01

    The barn owl midbrain contains mutually aligned maps of auditory and visual space. Throughout life, map alignment is maintained through the actions of an instructive signal that encodes the magnitude of auditory-visual mismatch. The intracellular signaling pathways activated by this signal are unknown. Here we tested the hypothesis that CREB (cAMP response element-binding protein) provides a cell-specific readout of instructive information. Owls were fitted with prismatic or control spectacles and provided rich auditory-visual experience: hunting live mice. CREB activation was analyzed within 30 min of hunting using phosphorylation state-specific CREB (pCREB) and CREB antibodies, confocal imaging, and immunofluorescence measurements at individual cell nuclei. In control owls or prism-adapted owls, which experience small instructive signals, the frequency distributions of pCREB/CREB values obtained for cell nuclei within the external nucleus of the inferior colliculus (ICX) were unimodal. In contrast, in owls adapting to prisms or readapting to normal conditions, the distributions were bimodal: certain cells had received a signal that positively regulated CREB and, by extension, transcription of CREB-dependent genes, whereas others received a signal that negatively regulated it. These changes were restricted to the subregion of the inferior colliculus that received optically displaced input, the rostral ICX, and were not evident in the caudal ICX or central nucleus. Finally, the topographic pattern of CREB regulation was patchy, not continuous, as expected from the actions of a topographically precise signal encoding discrete events. These results support a model in which the magnitude of CREB activation within individual cells provides a readout of the instructive signal that guides plasticity and learning. PMID:18829948

  10. Regulators and effectors of bone morphogenetic protein signalling in the cardiovascular system.

    PubMed

    Luo, Jiang-Yun; Zhang, Yang; Wang, Li; Huang, Yu

    2015-07-15

    Bone morphogenetic proteins (BMPs) play key roles in the regulation of cell proliferation, differentiation and apoptosis in various tissues and organs, including the cardiovascular system. BMPs signal through both Smad-dependent and -independent cascades to exert a wide spectrum of biological activities. Cardiovascular disorders such as abnormal angiogenesis, atherosclerosis, pulmonary hypertension and cardiac hypertrophy have been linked to aberrant BMP signalling. To correct the dysregulated BMP signalling in cardiovascular pathogenesis, it is essential to get a better understanding of how the regulators and effectors of BMP signalling control cardiovascular function and how the dysregulated BMP signalling contributes to cardiovascular dysfunction. We hence highlight several key regulators of BMP signalling such as extracellular regulators of ligands, mechanical forces, microRNAs and small molecule drugs as well as typical BMP effectors like direct downstream target genes, mitogen-activated protein kinases, reactive oxygen species and microRNAs. The insights into these molecular processes will help target both the regulators and important effectors to reverse BMP-associated cardiovascular pathogenesis. PMID:25952563

  11. Regulators and effectors of bone morphogenetic protein signalling in the cardiovascular system.

    PubMed

    Luo, Jiang-Yun; Zhang, Yang; Wang, Li; Huang, Yu

    2015-07-15

    Bone morphogenetic proteins (BMPs) play key roles in the regulation of cell proliferation, differentiation and apoptosis in various tissues and organs, including the cardiovascular system. BMPs signal through both Smad-dependent and -independent cascades to exert a wide spectrum of biological activities. Cardiovascular disorders such as abnormal angiogenesis, atherosclerosis, pulmonary hypertension and cardiac hypertrophy have been linked to aberrant BMP signalling. To correct the dysregulated BMP signalling in cardiovascular pathogenesis, it is essential to get a better understanding of how the regulators and effectors of BMP signalling control cardiovascular function and how the dysregulated BMP signalling contributes to cardiovascular dysfunction. We hence highlight several key regulators of BMP signalling such as extracellular regulators of ligands, mechanical forces, microRNAs and small molecule drugs as well as typical BMP effectors like direct downstream target genes, mitogen-activated protein kinases, reactive oxygen species and microRNAs. The insights into these molecular processes will help target both the regulators and important effectors to reverse BMP-associated cardiovascular pathogenesis.

  12. AthaMap web tools for the analysis and identification of co-regulated genes.

    PubMed

    Galuschka, Claudia; Schindler, Martin; Bülow, Lorenz; Hehl, Reinhard

    2007-01-01

    The AthaMap database generates a map of cis-regulatory elements for the whole Arabidopsis thaliana genome. This database has been extended by new tools to identify common cis-regulatory elements in specific regions of user-provided gene sets. A resulting table displays all cis-regulatory elements annotated in AthaMap including positional information relative to the respective gene. Further tables show overviews with the number of individual transcription factor binding sites (TFBS) present and TFBS common to the whole set of genes. Over represented cis-elements are easily identified. These features were used to detect specific enrichment of drought-responsive elements in cold-induced genes. For identification of co-regulated genes, the output table of the colocalization function was extended to show the closest genes and their relative distances to the colocalizing TFBS. Gene sets determined by this function can be used for a co-regulation analysis in microarray gene expression databases such as Genevestigator or PathoPlant. Additional improvements of AthaMap include display of the gene structure in the sequence window and a significant data increase. AthaMap is freely available at http://www.athamap.de/. PMID:17148485

  13. Mitogen-activated protein kinase phosphatase 1 negatively regulates MAPK signaling in mouse hypothalamus.

    PubMed

    Adachi, Koichi; Goto, Motomitsu; Onoue, Takeshi; Tsunekawa, Taku; Shibata, Miyuki; Hagimoto, Shigeru; Ito, Yoshihiro; Banno, Ryoichi; Suga, Hidetaka; Sugimura, Yoshihisa; Oiso, Yutaka; Arima, Hiroshi

    2014-05-21

    Mitogen-activated protein kinase phosphatase 1 (MKP-1) is shown to negatively regulate MAPK signaling in various peripheral tissues as well as the central nervous system such as cortex, striatum and hippocampus. In this study, we examined whether MKP-1 regulates MAPK signaling in the mouse hypothalamus. Intraperitoneal injection of TNFα significantly increased MKP-1 mRNA expression in paraventricular and arcuate nuclei in the hypothalamus. TNFα treatment induced increases in MKP-1 expression at both mRNA and protein levels, accompanied by the inactivation of MAPK signaling in mouse hypothalamic explants. Inhibition of MKP-1 by its inhibitor or siRNA increased MAPK activity in the explants. Our data indicate that MKP-1 negatively regulates MAPK signaling in the mouse hypothalamus.

  14. Angiogenic factor signaling regulates centrosome duplication in endothelial cells of developing blood vessels

    PubMed Central

    Taylor, Sarah M.; Nevis, Kathleen R.; Park, Hannah L.; Rogers, Gregory C.; Rogers, Stephen L.; Cook, Jeanette G.

    2010-01-01

    Regulated vascular endothelial growth factor (VEGF) signaling is required for proper angiogenesis, and excess VEGF signaling results in aberrantly formed vessels that do not function properly. Tumor endothelial cells have excess centrosomes and are aneuploid, properties that probably contribute to the morphologic and functional abnormalities of tumor vessels. We hypothesized that endothelial cell centrosome number is regulated by signaling via angiogenic factors, such as VEGF. We found that endothelial cells in developing vessels exposed to elevated VEGF signaling display centrosome overduplication. Signaling from VEGF, through either MEK/ERK or AKT to cyclin E/Cdk2, is amplified in association with centrosome overduplication, and blockade of relevant pathway components rescued the centrosome overduplication defect. Endothelial cells exposed to elevated FGF also had excess centrosomes, suggesting that multiple angiogenic factors regulate centrosome number. Endothelial cells with excess centrosomes survived and formed aberrant spindles at mitosis. Developing vessels exposed to elevated VEGF signaling also exhibited increased aneuploidy of endothelial cells, which is associated with cellular dysfunction. These results provide the first link between VEGF signaling and regulation of the centrosome duplication cycle, and suggest that endothelial cell centrosome overduplication contributes to aberrant angiogenesis in developing vessel networks exposed to excess angiogenic factors. PMID:20664058

  15. Astrocyte sodium signaling and the regulation of neurotransmission.

    PubMed

    Kirischuk, Sergei; Héja, László; Kardos, Julianna; Billups, Brian

    2016-10-01

    The transmembrane Na(+) concentration gradient is an important source of energy required not only to enable the generation of action potentials in excitable cells, but also for various transmembrane transporters both in excitable and non-excitable cells, like astrocytes. One of the vital functions of astrocytes in the central nervous system (CNS) is to regulate neurotransmitter concentrations in the extracellular space. Most neurotransmitters in the CNS are removed from the extracellular space by Na(+) -dependent neurotransmitter transporters (NeuTs) expressed both in neurons and astrocytes. Neuronal NeuTs control mainly phasic synaptic transmission, i.e., synaptically induced transient postsynaptic potentials, while astrocytic NeuTs contribute to the termination of phasic neurotransmission and modulate the tonic tone, i.e., the long-lasting activation of extrasynaptic receptors by neurotransmitter that has diffused out of the synaptic cleft. Consequently, local intracellular Na(+) ([Na(+) ]i ) transients occurring in astrocytes, for example via the activation of ionotropic neurotransmitter receptors, can affect the driving force for neurotransmitter uptake, in turn modulating the spatio-temporal profiles of neurotransmitter levels in the extracellular space. As some NeuTs are close to thermodynamic equilibrium under resting conditions, an increase in astrocytic [Na(+) ]i can stimulate the direct release of neurotransmitter via NeuT reversal. In this review we discuss the role of astrocytic [Na(+) ]i changes in the regulation of uptake/release of neurotransmitters. It is emphasized that an activation of one neurotransmitter system, including either its ionotropic receptor or Na(+) -coupled co-transporter, can strongly influence, or even reverse, other Na(+) -dependent NeuTs, with potentially significant consequences for neuronal communication. GLIA 2016;64:1655-1666. PMID:26566753

  16. Astrocyte sodium signaling and the regulation of neurotransmission.

    PubMed

    Kirischuk, Sergei; Héja, László; Kardos, Julianna; Billups, Brian

    2016-10-01

    The transmembrane Na(+) concentration gradient is an important source of energy required not only to enable the generation of action potentials in excitable cells, but also for various transmembrane transporters both in excitable and non-excitable cells, like astrocytes. One of the vital functions of astrocytes in the central nervous system (CNS) is to regulate neurotransmitter concentrations in the extracellular space. Most neurotransmitters in the CNS are removed from the extracellular space by Na(+) -dependent neurotransmitter transporters (NeuTs) expressed both in neurons and astrocytes. Neuronal NeuTs control mainly phasic synaptic transmission, i.e., synaptically induced transient postsynaptic potentials, while astrocytic NeuTs contribute to the termination of phasic neurotransmission and modulate the tonic tone, i.e., the long-lasting activation of extrasynaptic receptors by neurotransmitter that has diffused out of the synaptic cleft. Consequently, local intracellular Na(+) ([Na(+) ]i ) transients occurring in astrocytes, for example via the activation of ionotropic neurotransmitter receptors, can affect the driving force for neurotransmitter uptake, in turn modulating the spatio-temporal profiles of neurotransmitter levels in the extracellular space. As some NeuTs are close to thermodynamic equilibrium under resting conditions, an increase in astrocytic [Na(+) ]i can stimulate the direct release of neurotransmitter via NeuT reversal. In this review we discuss the role of astrocytic [Na(+) ]i changes in the regulation of uptake/release of neurotransmitters. It is emphasized that an activation of one neurotransmitter system, including either its ionotropic receptor or Na(+) -coupled co-transporter, can strongly influence, or even reverse, other Na(+) -dependent NeuTs, with potentially significant consequences for neuronal communication. GLIA 2016;64:1655-1666.

  17. Gene-Environment Interactions Target Mitogen-activated Protein 3 Kinase 1 (MAP3K1) Signaling in Eyelid Morphogenesis*

    PubMed Central

    Mongan, Maureen; Meng, Qinghang; Wang, Jingjing; Kao, Winston W.-Y.; Puga, Alvaro; Xia, Ying

    2015-01-01

    Gene-environment interactions determine the biological outcomes through mechanisms that are poorly understood. Mouse embryonic eyelid closure is a well defined model to study the genetic control of developmental programs. Using this model, we investigated how exposure to dioxin-like environmental pollutants modifies the genetic risk of developmental abnormalities. Our studies reveal that mitogen-activated protein 3 kinase 1 (MAP3K1) signaling is a focal point of gene-environment cross-talk. Dioxin exposure, acting through the aryl hydrocarbon receptor (AHR), blocked eyelid closure in genetic mutants in which MAP3K1 signaling was attenuated but did not disturb this developmental program in either wild type or mutant mice with attenuated epidermal growth factor receptor or WNT signaling. Exposure also markedly inhibited c-Jun phosphorylation in Map3k1+/− embryonic eyelid epithelium, suggesting that dioxin-induced AHR pathways can synergize with gene mutations to inhibit MAP3K1 signaling. Our studies uncover a novel mechanism through which the dioxin-AHR axis interacts with the MAP3K1 signaling pathways during fetal development and provide strong empirical evidence that specific gene alterations can increase the risk of developmental abnormalities driven by environmental pollutant exposure. PMID:26109068

  18. Fuz Regulates Craniofacial Development through Tissue Specific Responses to Signaling Factors

    PubMed Central

    Zhang, Zichao; Wlodarczyk, Bogdan J.; Niederreither, Karen; Venugopalan, Shankar; Florez, Sergio; Finnell, Richard H.; Amendt, Brad A.

    2011-01-01

    The planar cell polarity effector gene Fuz regulates ciliogenesis and Fuz loss of function studies reveal an array of embryonic phenotypes. However, cilia defects can affect many signaling pathways and, in humans, cilia defects underlie several craniofacial anomalies. To address this, we analyzed the craniofacial phenotype and signaling responses of the Fuz−/− mice. We demonstrate a unique role for Fuz in regulating both Hedgehog (Hh) and Wnt/β-catenin signaling during craniofacial development. Fuz expression first appears in the dorsal tissues and later in ventral tissues and craniofacial regions during embryonic development coincident with cilia development. The Fuz−/− mice exhibit severe craniofacial deformities including anophthalmia, agenesis of the tongue and incisors, a hypoplastic mandible, cleft palate, ossification/skeletal defects and hyperplastic malformed Meckel's cartilage. Hh signaling is down-regulated in the Fuz null mice, while canonical Wnt signaling is up-regulated revealing the antagonistic relationship of these two pathways. Meckel's cartilage is expanded in the Fuz−/− mice due to increased cell proliferation associated with the up-regulation of Wnt canonical target genes and decreased non-canonical pathway genes. Interestingly, cilia development was decreased in the mandible mesenchyme of Fuz null mice, suggesting that cilia may antagonize Wnt signaling in this tissue. Furthermore, expression of Fuz decreased expression of Wnt pathway genes as well as a Wnt-dependent reporter. Finally, chromatin IP experiments demonstrate that β-catenin/TCF-binding directly regulates Fuz expression. These data demonstrate a new model for coordination of Hh and Wnt signaling and reveal a Fuz-dependent negative feedback loop controlling Wnt/β-catenin signaling. PMID:21935430

  19. Impact of ACTH Signaling on Transcriptional Regulation of Steroidogenic Genes

    PubMed Central

    Ruggiero, Carmen; Lalli, Enzo

    2016-01-01

    The trophic peptide hormone adrenocorticotropic (ACTH) stimulates steroid hormone biosynthesis evoking both a rapid, acute response and a long-term, chronic response, via the activation of cAMP/protein kinase A (PKA) signaling. The acute response is initiated by the mobilization of cholesterol from lipid stores and its delivery to the inner mitochondrial membrane, a process that is mediated by the steroidogenic acute regulatory protein. The chronic response results in the increased coordinated transcription of genes encoding steroidogenic enzymes. ACTH binding to its cognate receptor, melanocortin 2 receptor (MC2R), stimulates adenylyl cyclase, thus inducing cAMP production, PKA activation, and phosphorylation of specific nuclear factors, which bind to target promoters and facilitate coactivator protein recruitment to direct steroidogenic gene transcription. This review provides a general view of the transcriptional control exerted by the ACTH/cAMP system on the expression of genes encoding for steroidogenic enzymes in the adrenal cortex. Special emphasis will be given to the transcription factors required to mediate ACTH-dependent transcription of steroidogenic genes. PMID:27065945

  20. Activity-Dependent Regulation of Substance P Expression and Topographic Map Maintenance by a Cholinergic Pathway

    PubMed Central

    Tu, Shichun; Butt, Christopher M.; Pauly, James R.; Debski, Elizabeth A.

    2008-01-01

    We have assessed the role of activity in the adult frog visual system in modulating two aspects of neuronal plasticity: neurotransmitter expression and topographic map maintenance. Chronic treatment of one tectal lobe with the non-NMDA receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione decreased the percentage of substance P-like immunoreactive (SP-IR) tectal cells in the untreated lobe while disrupting topographic map formation in the treated one. Treatment with the NMDA receptor antagonist d-(−)-2-amino-5-phosphonovaleric acid (d-AP-5) disrupted the topographic map but had no affect on SP-IR cells. These results indicate that maintenance of the topographic map is dependent on direct input from the glutamatergic retinal ganglion cells, whereas substance P (SP) expression is being regulated by a pathway that relays activity from one tectal lobe to the other. Such a pathway is provided by the cholinergic nucleus isthmi, which is reciprocally connected to the ipsilateral tectum and sends a projection to the contralateral one. Mecamylamine and atropine, antagonists of nicotinic and muscarinic receptors, respectively, were used together to block all cholinergic activity or alone to block receptor subclass activity. All three treatments decreased SP expression and disrupted the topographic map in the treated tectal lobe. We conclude that both SP expression and topographic map maintenance in the adult optic tectum are activity-dependent processes. Although our results are consistent with the maintenance of the topographic map through an NMDA receptor-based mechanism, they suggest that SP expression is regulated by a cholinergic interaction that depends on retinal ganglion cell input only for its activation. PMID:10884319

  1. Carbonylation Modification Regulates Na/K-ATPase Signaling and Salt Sensitivity: A Review and a Hypothesis

    PubMed Central

    Shah, Preeya T.; Martin, Rebecca; Yan, Yanling; Shapiro, Joseph I.; Liu, Jiang

    2016-01-01

    Na/K-ATPase signaling has been implicated in different physiological and pathophysiological conditions. Accumulating evidence indicates that oxidative stress not only regulates the Na/K-ATPase enzymatic activity, but also regulates its signaling and other functions. While cardiotonic steroids (CTS)-induced increase in reactive oxygen species (ROS) generation is an intermediate step in CTS-mediated Na/K-ATPase signaling, increase in ROS alone also stimulates Na/K-ATPase signaling. Based on literature and our observations, we hypothesize that ROS have biphasic effects on Na/K-ATPase signaling, transcellular sodium transport, and urinary sodium excretion. Oxidative modulation, in particular site specific carbonylation of the Na/K-ATPase α1 subunit, is a critical step in proximal tubular Na/K-ATPase signaling and decreased transcellular sodium transport leading to increases in urinary sodium excretion. However, once this system is overstimulated, the signaling, and associated changes in sodium excretion are blunted. This review aims to evaluate ROS-mediated carbonylation of the Na/K-ATPase, and its potential role in the regulation of pump signaling and sodium reabsorption in the renal proximal tubule (RPT). PMID:27445847

  2. Carbonylation Modification Regulates Na/K-ATPase Signaling and Salt Sensitivity: A Review and a Hypothesis.

    PubMed

    Shah, Preeya T; Martin, Rebecca; Yan, Yanling; Shapiro, Joseph I; Liu, Jiang

    2016-01-01

    Na/K-ATPase signaling has been implicated in different physiological and pathophysiological conditions. Accumulating evidence indicates that oxidative stress not only regulates the Na/K-ATPase enzymatic activity, but also regulates its signaling and other functions. While cardiotonic steroids (CTS)-induced increase in reactive oxygen species (ROS) generation is an intermediate step in CTS-mediated Na/K-ATPase signaling, increase in ROS alone also stimulates Na/K-ATPase signaling. Based on literature and our observations, we hypothesize that ROS have biphasic effects on Na/K-ATPase signaling, transcellular sodium transport, and urinary sodium excretion. Oxidative modulation, in particular site specific carbonylation of the Na/K-ATPase α1 subunit, is a critical step in proximal tubular Na/K-ATPase signaling and decreased transcellular sodium transport leading to increases in urinary sodium excretion. However, once this system is overstimulated, the signaling, and associated changes in sodium excretion are blunted. This review aims to evaluate ROS-mediated carbonylation of the Na/K-ATPase, and its potential role in the regulation of pump signaling and sodium reabsorption in the renal proximal tubule (RPT).

  3. Regulation of the BMP Signaling-Responsive Transcriptional Network in the Drosophila Embryo

    PubMed Central

    Saunders, Abbie; Wilcockson, Scott G.; Zeef, Leo A. H.; Donaldson, Ian J.; Ashe, Hilary L.

    2016-01-01

    The BMP signaling pathway has a conserved role in dorsal-ventral axis patterning during embryonic development. In Drosophila, graded BMP signaling is transduced by the Mad transcription factor and opposed by the Brinker repressor. In this study, using the Drosophila embryo as a model, we combine RNA-seq with Mad and Brinker ChIP-seq to decipher the BMP-responsive transcriptional network underpinning differentiation of the dorsal ectoderm during dorsal-ventral axis patterning. We identify multiple new BMP target genes, including positive and negative regulators of EGF signaling. Manipulation of EGF signaling levels by loss- and gain-of-function studies reveals that EGF signaling negatively regulates embryonic BMP-responsive transcription. Therefore, the BMP gene network has a self-regulating property in that it establishes a balance between its activity and that of the antagonistic EGF signaling pathway to facilitate correct patterning. In terms of BMP-dependent transcription, we identify key roles for the Zelda and Zerknüllt transcription factors in establishing the resulting expression domain, and find widespread binding of insulator proteins to the Mad and Brinker-bound genomic regions. Analysis of embryos lacking the BEAF-32 insulator protein shows reduced transcription of a peak BMP target gene and a reduction in the number of amnioserosa cells, the fate specified by peak BMP signaling. We incorporate our findings into a model for Mad-dependent activation, and discuss its relevance to BMP signal interpretation in vertebrates. PMID:27379389

  4. MicroRNA-142-3p Negatively Regulates Canonical Wnt Signaling Pathway

    PubMed Central

    Hu, Tanyu; Phiwpan, Krung; Guo, Jitao; Zhang, Wei; Guo, Jie; Zhang, Zhongmei; Zou, Mangge; Zhang, Xuejie; Zhang, Jianhua

    2016-01-01

    Wnt/β-catenin signaling pathway plays essential roles in mammalian development and tissue homeostasis. MicroRNAs (miRNAs) are a class of regulators involved in modulating this pathway. In this study, we screened miRNAs regulating Wnt/β-catenin signaling by using a TopFlash based luciferase reporter. Surprisingly, we found that miR-142 inhibited Wnt/β-catenin signaling, which was inconsistent with a recent study showing that miR-142-3p targeted Adenomatous Polyposis Coli (APC) to upregulate Wnt/β-catenin signaling. Due to the discordance, we elaborated experiments by using extensive mutagenesis, which demonstrated that the stem-loop structure was important for miR-142 to efficiently suppress Wnt/β-catenin signaling. Moreover, the inhibitory effect of miR-142 relies on miR-142-3p rather than miR-142-5p. Further, we found that miR-142-3p directly modulated translation of Ctnnb1 mRNA (encoding β-catenin) through binding to its 3’ untranslated region (3’ UTR). Finally, miR-142 was able to repress cell cycle progression by inhibiting active Wnt/β-catenin signaling. Thus, our findings highlight the inhibitory role of miR-142-3p in Wnt/β-catenin signaling, which help to understand the complex regulation of Wnt/β-catenin signaling. PMID:27348426

  5. Regulation of Notch signaling and endocytosis by the Lgl neoplastic tumor suppressor

    PubMed Central

    Portela, Marta; Parsons, Linda M; Grzeschik, Nicola A; Richardson, Helena E

    2015-01-01

    The evolutionarily conserved neoplastic tumor suppressor protein, Lethal (2) giant larvae (Lgl), plays roles in cell polarity and tissue growth via regulation of the Hippo pathway. In our recent study, we showed that in the developing Drosophila eye epithelium, depletion of Lgl leads to increased ligand-dependent Notch signaling. lgl mutant tissue also exhibits an accumulation of early endosomes, recycling endosomes, early-multivesicular body markers and acidic vesicles. We showed that elevated Notch signaling in lgl− tissue can be rescued by feeding larvae the vesicle de-acidifying drug chloroquine, revealing that Lgl attenuates Notch signaling by limiting vesicle acidification. Strikingly, chloroquine also rescued the lgl− overgrowth phenotype, suggesting that the Hippo pathway defects were also rescued. In this extraview, we provide additional data on the regulation of Notch signaling and endocytosis by Lgl, and discuss possible mechanisms by which Lgl depletion contributes to signaling pathway defects and tumorigenesis. PMID:25789785

  6. RGS1 regulates myeloid cell accumulation in atherosclerosis and aortic aneurysm rupture through altered chemokine signalling

    PubMed Central

    Patel, Jyoti; McNeill, Eileen; Douglas, Gillian; Hale, Ashley B.; de Bono, Joseph; Lee, Regent; Iqbal, Asif J.; Regan-Komito, Daniel; Stylianou, Elena; Greaves, David R.; Channon, Keith M.

    2015-01-01

    Chemokine signalling drives monocyte recruitment in atherosclerosis and aortic aneurysms. The mechanisms that lead to retention and accumulation of macrophages in the vascular wall remain unclear. Regulator of G-Protein Signalling-1 (RGS1) deactivates G-protein signalling, reducing the response to sustained chemokine stimulation. Here we show that Rgs1 is upregulated in atherosclerotic plaque and aortic aneurysms. Rgs1 reduces macrophage chemotaxis and desensitizes chemokine receptor signalling. In early atherosclerotic lesions, Rgs1 regulates macrophage accumulation and is required for the formation and rupture of Angiotensin II-induced aortic aneurysms, through effects on leukocyte retention. Collectively, these data reveal a role for Rgs1 in leukocyte trafficking and vascular inflammation and identify Rgs1, and inhibition of chemokine receptor signalling as potential therapeutic targets in vascular disease. PMID:25782711

  7. Probabilistic storm surge inundation maps for Metro Manila based on Philippine public storm warning signals

    NASA Astrophysics Data System (ADS)

    Tablazon, J.; Caro, C. V.; Lagmay, A. M. F.; Briones, J. B. L.; Dasallas, L.; Lapidez, J. P.; Santiago, J.; Suarez, J. K.; Ladiero, C.; Gonzalo, L. A.; Mungcal, M. T. F.; Malano, V.

    2015-03-01

    A storm surge is the sudden rise of sea water over the astronomical tides, generated by an approaching storm. This event poses a major threat to the Philippine coastal areas, as manifested by Typhoon Haiyan on 8 November 2013. This hydro-meteorological hazard is one of the main reasons for the high number of casualties due to the typhoon, with 6300 deaths. It became evident that the need to develop a storm surge inundation map is of utmost importance. To develop these maps, the Nationwide Operational Assessment of Hazards under the Department of Science and Technology (DOST-Project NOAH) simulated historical tropical cyclones that entered the Philippine Area of Responsibility. The Japan Meteorological Agency storm surge model was used to simulate storm surge heights. The frequency distribution of the maximum storm surge heights was calculated using simulation results of tropical cyclones under a specific public storm warning signal (PSWS) that passed through a particular coastal area. This determines the storm surge height corresponding to a given probability of occurrence. The storm surge heights from the model were added to the maximum astronomical tide data from WXTide software. The team then created maps of inundation for a specific PSWS using the probability of exceedance derived from the frequency distribution. Buildings and other structures were assigned a probability of exceedance depending on their occupancy category, i.e., 1% probability of exceedance for critical facilities, 10% probability of exceedance for special occupancy structures, and 25% for standard occupancy and miscellaneous structures. The maps produced show the storm-surge-vulnerable areas in Metro Manila, illustrated by the flood depth of up to 4 m and extent of up to 6.5 km from the coastline. This information can help local government units in developing early warning systems, disaster preparedness and mitigation plans, vulnerability assessments, risk-sensitive land use plans, shoreline

  8. Genome-wide identification of phospho-regulators of Wnt signaling in Drosophila.

    PubMed

    Swarup, Sharan; Pradhan-Sundd, Tirthadipa; Verheyen, Esther M

    2015-04-15

    Evolutionarily conserved intercellular signaling pathways regulate embryonic development and adult tissue homeostasis in metazoans. The precise control of the state and amplitude of signaling pathways is achieved in part through the kinase- and phosphatase-mediated reversible phosphorylation of proteins. In this study, we performed a genome-wide in vivo RNAi screen for kinases and phosphatases that regulate the Wnt pathway under physiological conditions in the Drosophila wing disc. Our analyses have identified 54 high-confidence kinases and phosphatases capable of modulating the Wnt pathway, including 22 novel regulators. These candidates were also assayed for a role in the Notch pathway, and numerous phospho-regulators were identified. Additionally, each regulator of the Wnt pathway was evaluated in the wing disc for its ability to affect the mechanistically similar Hedgehog pathway. We identified 29 dual regulators that have the same effect on the Wnt and Hedgehog pathways. As proof of principle, we established that Cdc37 and Gilgamesh/CK1γ inhibit and promote signaling, respectively, by functioning at analogous levels of these pathways in both Drosophila and mammalian cells. The Wnt and Hedgehog pathways function in tandem in multiple developmental contexts, and the identification of several shared phospho-regulators serve as potential nodes of control under conditions of aberrant signaling and disease. PMID:25852200

  9. Porcine circovirus type 2 replication is impaired by inhibition of the extracellular signal-regulated kinase (ERK) signaling pathway

    SciTech Connect

    Wei Li; Liu Jue

    2009-03-30

    Postweaning multisystemic wasting syndrome, which is primarily caused by porcine circovirus type 2 (PCV2), is an emerging and important swine disease. We have recently shown that PCV2 induces nuclear factor kappa B activation and its activation is required for active replication, but the other cellular factors involved in PCV2 replication are not well defined. The extracellular signal-regulated kinase (ERK) which served as an important component of cellular signal transduction pathways has been shown to regulate many viral infections. In this report, we show that PCV2 activates ERK1/2 in PCV2-infected PK15 cells dependent on viral replication. The PCV2-induced ERK1/2 leads to phosphorylation of the ternary complex factor Elk-1, which kinetically paralleled ERK1/2 activation. Inhibition of ERK activation with U0126, a specific MEK1/2 inhibitor, significantly reduced viral progeny release. Investigations into the mechanism of ERK1/2 regulation revealed that inhibition of ERK activation leads to decreased viral transcription and lower virus protein expression. These data indicate that the ERK signaling pathway is involved in PCV2 infection and beneficial to PCV2 replication in the cultured cells.

  10. Regulation of cell division and expansion by sugar and auxin signaling

    PubMed Central

    Wang, Lu; Ruan, Yong-Ling

    2013-01-01

    Plant growth and development are modulated by concerted actions of a variety of signaling molecules. In recent years, evidence has emerged on the roles of sugar and auxin signals network in diverse aspects of plant growth and development. Here, based on recent progress of genetic analyses and gene expression profiling studies, we summarize the functional similarities, diversities, and their interactions of sugar and auxin signals in regulating two major processes of plant development: cell division and cell expansion. We focus on roles of sugar and auxin signaling in both vegetative and reproductive tissues including developing seed. PMID:23755057

  11. Signaling and regulation of G protein-coupled receptors in airway smooth muscle

    PubMed Central

    Billington, Charlotte K; Penn, Raymond B

    2003-01-01

    Signaling through G protein-coupled receptors (GPCRs) mediates numerous airway smooth muscle (ASM) functions including contraction, growth, and "synthetic" functions that orchestrate airway inflammation and promote remodeling of airway architecture. In this review we provide a comprehensive overview of the GPCRs that have been identified in ASM cells, and discuss the extent to which signaling via these GPCRs has been characterized and linked to distinct ASM functions. In addition, we examine the role of GPCR signaling and its regulation in asthma and asthma treatment, and suggest an integrative model whereby an imbalance of GPCR-derived signals in ASM cells contributes to the asthmatic state. PMID:12648290

  12. Signaling Networks Regulating Development of the Lower Respiratory Tract

    PubMed Central

    Ornitz, David M.; Yin, Yongjun

    2012-01-01

    The lungs serve the primary function of air-blood gas exchange in all mammals and in terrestrial vertebrates. Efficient gas exchange requires a large surface area that provides intimate contact between the atmosphere and the circulatory system. To achieve this, the lung contains a branched conducting system (the bronchial tree) and specialized air-blood gas exchange units (the alveoli). The conducting system brings air from the external environment to the alveoli and functions to protect the lung from debris that could obstruct airways, from entry of pathogens, and from excessive loss of fluids. The distal lung enables efficient exchange of gas between the alveoli and the conducting system and between the alveoli and the circulatory system. In this article, we highlight developmental and physiological mechanisms that specify, pattern, and regulate morphogenesis of this complex and essential organ. Recent advances have begun to define molecular mechanisms that control many of the important processes required for lung organogenesis; however, many questions remain. A deeper understanding of these molecular mechanisms will aid in the diagnosis and treatment of congenital lung disease and in the development of strategies to enhance the reparative response of the lung to injury and eventually permit regeneration of functional lung tissue. PMID:22550231

  13. Desmoglein 3-Dependent Signaling Regulates Keratinocyte Migration and Wound Healing.

    PubMed

    Rötzer, Vera; Hartlieb, Eva; Winkler, Julia; Walter, Elias; Schlipp, Angela; Sardy, Miklós; Spindler, Volker; Waschke, Jens

    2016-01-01

    The desmosomal transmembrane adhesion molecules desmoglein 3 (Dsg3) and desmocollin 3 (Dsc3) are required for strong keratinocyte cohesion. Recently, we have shown that Dsg3 associates with p38 mitogen-activated protein kinase (p38MAPK) and suppresses its activity. Here, we further investigated the role of Dsg3-dependent control of p38MAPK function. Dsg3-deficient mice display recurrent spontaneously healing skin erosions. In lesional and perilesional biopsies, p38MAPK activation was detectable compared with control animals. This led us to speculate that Dsg3 regulates wound repair in a p38MAPK-dependent manner. Indeed, scratch-wounded keratinocyte monolayers exhibited p38MAPK activation and loss of Dsg3 in cells lining the wound edge. Human keratinocytes after silencing of Dsg3 as well as primary cells isolated from Dsg3 knockout animals exhibited accelerated migration, which was further corroborated in an ex vivo skin outgrowth assay. Importantly, migration was efficiently blocked by inhibition of p38MAPK, indicating that p38MAPK mediates the effects observed upon loss of Dsg3. In line with this, we show that levels of active p38MAPK associated with Dsc3 are increased in Dsg3-deficient cells. These data indicate that Dsg3 controls a switch from an adhesive to a migratory keratinocyte phenotype via p38MAPK inhibition. Thus, loss of Dsg3 adhesion may foster wound closure by allowing p38MAPK-dependent migration. PMID:26763450

  14. Purinergic Signaling as a Regulator of Th17 Cell Plasticity

    PubMed Central

    Fernández, Dominique; Flores-Santibáñez, Felipe; Neira, Jocelyn; Osorio-Barrios, Francisco; Tejón, Gabriela; Nuñez, Sarah; Hidalgo, Yessia; Fuenzalida, Maria Jose; Meza, Daniel; Ureta, Gonzalo; Lladser, Alvaro; Pacheco, Rodrigo; Acuña-Castillo, Claudio; Guixé, Victoria; Quintana, Francisco J.; Bono, Maria Rosa; Rosemblatt, Mario; Sauma, Daniela

    2016-01-01

    T helper type 17 (Th17) lymphocytes, characterized by the production of interleukin-17 and other pro-inflammatory cytokines, are present in intestinal lamina propria and have been described as important players driving intestinal inflammation. Recent evidence, supporting the notion of a functional and phenotypic instability of Th17 cells, has shown that Th17 differentiate into type 1 regulatory (Tr1) T cells during the resolution of intestinal inflammation. Moreover, it has been suggested that the expression of CD39 ectonucleotidase endows Th17 cells with immunosuppressive properties. However, the exact role of CD39 ectonucleotidase in Th17 cells has not been studied in the context of intestinal inflammation. Here we show that Th17 cells expressing CD39 ectonucleotidase can hydrolyze ATP and survive to ATP-induced cell death. Moreover, in vitro-generated Th17 cells expressing the CD39 ectonucleotidase produce IL-10 and are less pathogenic than CD39 negative Th17 cells in a model of experimental colitis in Rag-/- mice. Remarkably, we show that CD39 activity regulates the conversion of Th17 cells to IL-10-producing cells in vitro, which is abrogated in the presence of ATP and the CD39-specific inhibitor ARL67156. All these data suggest that CD39 expression by Th17 cells allows the depletion of ATP and is crucial for IL-10 production and survival during the resolution of intestinal inflammation. PMID:27322617

  15. CD28 and ITK signals regulate autoreactive T cell trafficking

    PubMed Central

    Jain, Nitya; Miu, Bing; Jiang, Jian-kang; McKinstry, Kai K.; Prince, Amanda; Swain, Susan L; Greiner, Dale L.; Thomas, Craig J.; Sanderson, Michael J.; Berg, Leslie J; Kang, Joonsoo

    2013-01-01

    Activation of self-reactive T cells and their trafficking to target tissues leads to autoimmune organ destruction. Mice lacking the coinhibitory receptor CTLA-4 develop fatal autoimmunity characterized by massive lymphocytic invasion into non-lymphoid tissues. Here we demonstrate that the CD28 costimulatory pathway regulates the trafficking of self-reactive Ctla4−/− T cells to tissues. Co-ablation of the CD28-activated Tec family kinase ITK does not block spontaneous T cell activation, but instead causes self-reactive Ctla4−/− T cells to accumulate in secondary lymphoid organs. Despite a fulminant autoimmune process in the lymphoid compartment, Itk−/−Ctla4−/− mice are otherwise healthy and exhibit a long lifespan. We propose that ITK licenses autoreactive T cells to enter tissues to mount destructive immune responses. Importantly, ITK inhibitors mimic the null mutant phenotype and also prevent pancreatic islet infiltration by diabetogenic T cells in mouse models of Type I diabetes, highlighting their potential utility for the treatment of human autoimmune disorders. PMID:24270545

  16. Calcitriol transmembrane signalling: regulation of rat muscle phospholipase D activity.

    PubMed

    Facchinetti, M M; Boland, R; de Boland, A R

    1998-01-01

    In rat skeletal muscle, calcitriol, the hormonal form of vitamin D3, rapidly stimulates the biphasic formation of diacylglycerol (DAG), the second phase being independent of phosphoinositide hydrolysis driven by phospholipase C. In this work we showed that the effect of calcitriol on the second phase of DAG formation was totally inhibited in the absence of extracellular Ca2+ and by the Ca2+-channel blockers nifedipine and verapamil, whereas the Ca2+ ionophore A23184, similar to calcitriol, increased DAG formation by 100%. GTPgammaS, which activates G protein-mediated signals, mimicked the effects of the hormone while GDPbetaS, an inhibitor of G proteins, suppressed calcitriol-induced DAG formation. To elucidate the metabolic pathway of the late phase of DAG production, we examined the contribution of phospholipase D (PLD), which acts on phosphatidylcholine (PC) generating phosphatidic acid that is converted to DAG by a phosphatidate phosphohydrolase. In [3H]arachidonate-labeled muscle, calcitriol increased [3H]phosphatidylethanol (PEt) formation in the presence of ethanol, a reaction specific for PLD. The effects of the hormone were time- and dose-dependent with maximum PEt levels achieved at 10(-9) M. The phorbol ester TPA also stimulated PEt formation. The combination of calcitriol and TPA was more effective than either compound alone. In rat muscle, calcitriol increased PKC activity in a time-dependent fashion. Bisindolymaleimide, a selective inhibitor of the enzyme, completely suppressed TPA-induced PEt and attenuated the effects of the hormone. These results provide the first evidence concerning calcitriol stimulation of the hydrolysis of PC in a mammalian tissue through a phospholipase D catalyzed mechanism involving Ca2+, protein kinase C, and G proteins.

  17. Resveratrol upregulates Egr-1 expression and activity involving extracellular signal-regulated protein kinase and ternary complex factors

    SciTech Connect

    Rössler, Oliver G.; Glatzel, Daniel; Thiel, Gerald

    2015-03-01

    Many intracellular functions have been attributed to resveratrol, a polyphenolic phytoalexin found in grapes and in other plants. Here, we show that resveratrol induces the expression of the transcription factor Egr-1 in human embryonic kidney cells. Using a chromosomally embedded Egr-1-responsive reporter gene, we show that the Egr-1 activity was significantly elevated in resveratrol-treated cells, indicating that the newly synthesized Egr-1 protein was biologically active. Stimulus-transcription coupling leading to the resveratrol-induced upregulation of Egr-1 expression and activity requires the protein kinases Raf and extracellular signal-regulated protein kinase ERK, while MAP kinase phosphatase-1 functions as a nuclear shut-off device that interrupts the signaling cascade connecting resveratrol stimulation with enhanced Egr-1 expression. On the transcriptional level, Elk-1, a key transcriptional regulator of serum response element-driven gene transcription, connects the intracellular signaling cascade elicited by resveratrol with transcription of the Egr-1 gene. These data were corroborated by the observation that stimulation of the cells with resveratrol increased the transcriptional activation potential of Elk-1. The SRE as well as the GC-rich DNA binding site of Egr-1 function as resveratrol-responsive elements. Thus, resveratrol regulates gene transcription via activation of the stimulus-regulated protein kinases Raf and ERK and the stimulus-responsive transcription factors TCF and Egr-1. - Highlights: • The plant polyphenol resveratrol upregulates Egr-1 expression and activity. • The stimulation of Egr-1 requires the protein kinases ERK and Raf. • Resveratrol treatment upregulates the transcriptional activation potential of Elk-1. • Resveratrol-induced stimulation of Egr-1 requires ternary complex factors. • Two distinct resveratrol-responsive elements were identified.

  18. REDOX regulation of IL-13 signaling in intestinal epithelial cells: usage of alternate pathways mediates distinct gene expression patterns

    PubMed Central

    Mandal, Debasmita; Fu, Pingfu; Levine, Alan D.

    2010-01-01

    In the classic view interleukin-13 (IL-13) binds to a heterodimer protein complex of the IL-13Rα1 and IL-4Rα chains and signals through a janus kinase 1 (JAK1)-signal transducer and activator of transcription 6 (STAT6) mechanism. We recently reported that IL-13 also signals through the IL-13Rα2 chain initiating all three mitogen activated protein kinase (MAPK) pathways, and the relative expression of IL-13Rα1 and IL-13Rα2 modulates one another’s transduction pathway. Therefore we investigated whether generation of reactive oxygen species (ROS) as second messengers may serve as a common nexus between these two pathways emanating from the individual IL-13 receptor chains in intestinal epithelial cells (IEC). IL-13 stimulates intracellular ROS synthesis within 5 min via IL-13Rα1-JAK1-STAT6- and IL-13Rα2-MEK1/2-ERK1/2-dependent activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-1 (NOX-1). IL-13-induced ROS generation in turn positively regulates phosphorylation of ERK1/2 and STAT6, yielding a feed forward amplification loop. IL-13 also stimulates the stable, long-term gene expression of two other NADPH oxidases, NOX-4 and DUOX-2, which along with constitutive NOX-1, might facilitate elevated, continuous production of ROS in IL-13-activated IEC. The contribution of each signal transduction pathway initiated by IL-13 engagement to such biological functions as wound healing, inflammation, and apoptosis was mapped for representative, responsive genes. Distinct usage patterns were observed, demonstrating that not only is IL-13 signal transduction through STAT6, MAPK, and ROS regulated in both an antagonistic and cyclic fashion, but each pathway also plays a specific role in modulating the wound healing and anti-apoptotic capabilities of the intestinal epithelium. PMID:20570727

  19. Chemical genetics reveals negative regulation of abscisic acid signaling by a plant immune response pathway.

    PubMed

    Kim, Tae-Houn; Hauser, Felix; Ha, Tracy; Xue, Shaowu; Böhmer, Maik; Nishimura, Noriyuki; Munemasa, Shintaro; Hubbard, Katharine; Peine, Nora; Lee, Byeong-Ha; Lee, Stephen; Robert, Nadia; Parker, Jane E; Schroeder, Julian I

    2011-06-01

    Coordinated regulation of protection mechanisms against environmental abiotic stress and pathogen attack is essential for plant adaptation and survival. Initial abiotic stress can interfere with disease-resistance signaling [1-6]. Conversely, initial plant immune signaling may interrupt subsequent abscisic acid (ABA) signal transduction [7, 8]. However, the processes involved in this crosstalk between these signaling networks have not been determined. By screening a 9600-compound chemical library, we identified a small molecule [5-(3,4-dichlorophenyl)furan-2-yl]-piperidine-1-ylmethanethione (DFPM) that rapidly downregulates ABA-dependent gene expression and also inhibits ABA-induced stomatal closure. Transcriptome analyses show that DFPM also stimulates expression of plant defense-related genes. Major early regulators of pathogen-resistance responses, including EDS1, PAD4, RAR1, and SGT1b, are required for DFPM-and notably also for Pseudomonas-interference with ABA signal transduction, whereas salicylic acid, EDS16, and NPR1 are not necessary. Although DFPM does not interfere with early ABA perception by PYR/RCAR receptors or ABA activation of SnRK2 kinases, it disrupts cytosolic Ca(2+) signaling and downstream anion channel activation in a PAD4-dependent manner. Our findings provide evidence that activation of EDS1/PAD4-dependent plant immune responses rapidly disrupts ABA signal transduction and that this occurs at the level of Ca(2+) signaling, illuminating how the initial biotic stress pathway interferes with ABA signaling.

  20. Differential volume regulation and calcium signaling in two ciliary body cell types is subserved by TRPV4 channels

    PubMed Central

    Jo, Andrew O.; Lakk, Monika; Frye, Amber M.; Phuong, Tam T. T.; Redmon, Sarah N.; Roberts, Robin; Berkowitz, Bruce A.; Yarishkin, Oleg; Križaj, David

    2016-01-01

    Fluid secretion by the ciliary body plays a critical and irreplaceable function in vertebrate vision by providing nutritive support to the cornea and lens, and by maintaining intraocular pressure. Here, we identify TRPV4 (transient receptor potential vanilloid isoform 4) channels as key osmosensors in nonpigmented epithelial (NPE) cells of the mouse ciliary body. Hypotonic swelling and the selective agonist GSK1016790A (EC50 ∼33 nM) induced sustained transmembrane cation currents and cytosolic [Ca2+]i elevations in dissociated and intact NPE cells. Swelling had no effect on [Ca2+]i levels in pigment epithelial (PE) cells, whereas depolarization evoked [Ca2+]i elevations in both NPE and PE cells. Swelling-evoked [Ca2+]i signals were inhibited by the TRPV4 antagonist HC067047 (IC50 ∼0.9 μM) and were absent in Trpv4−/− NPE. In NPE, but not PE, swelling-induced [Ca2+]i signals required phospholipase A2 activation. TRPV4 localization to NPE was confirmed with immunolocalization and excitation mapping approaches, whereas in vivo MRI analysis confirmed TRPV4-mediated signals in the intact mouse ciliary body. Trpv2 and Trpv4 were the most abundant vanilloid transcripts in CB. Overall, our results support a model whereby TRPV4 differentially regulates cell volume, lipid, and calcium signals in NPE and PE cell types and therefore represents a potential target for antiglaucoma medications. PMID:27006502

  1. Miro1 Regulates Activity-Driven Positioning of Mitochondria within Astrocytic Processes Apposed to Synapses to Regulate Intracellular Calcium Signaling.

    PubMed

    Stephen, Terri-Leigh; Higgs, Nathalie F; Sheehan, David F; Al Awabdh, Sana; López-Doménech, Guillermo; Arancibia-Carcamo, I Lorena; Kittler, Josef T

    2015-12-01

    It is fast emerging that maintaining mitochondrial function is important for regulating astrocyte function, although the specific mechanisms that govern astrocyte mitochondrial trafficking and positioning remain poorly understood. The mitochondrial Rho-GTPase 1 protein (Miro1) regulates mitochondrial trafficking and detachment from the microtubule transport network to control activity-dependent mitochondrial positioning in neurons. However, whether Miro proteins are important for regulating signaling-dependent mitochondrial dynamics in astrocytic processes remains unclear. Using live-cell confocal microscopy of rat organotypic hippocampal slices, we find that enhancing neuronal activity induces transient mitochondrial remodeling in astrocytes, with a concomitant, transient reduction in mitochondrial trafficking, mediated by elevations in intracellular Ca(2+). Stimulating neuronal activity also induced mitochondrial confinement within astrocytic processes in close proximity to synapses. Furthermore, we show that the Ca(2+)-sensing EF-hand domains of Miro1 are important for regulating mitochondrial trafficking in astrocytes and required for activity-driven mitochondrial confinement near synapses. Additionally, activity-dependent mitochondrial positioning by Miro1 reciprocally regulates the levels of intracellular Ca(2+) in astrocytic processes. Thus, the regulation of intracellular Ca(2+) signaling, dependent on Miro1-mediated mitochondrial positioning, could have important consequences for astrocyte Ca(2+) wave propagation, gliotransmission, and ultimately neuronal function. PMID:26631479

  2. Dopamine Signaling Regulates Fat Content through β-Oxidation in Caenorhabditis elegans

    PubMed Central

    Barros, Alexandre Guimarães de Almeida; Bridi, Jessika Cristina; de Souza, Bruno Rezende; de Castro Júnior, Célio; de Lima Torres, Karen Cecília; Malard, Leandro; Jorio, Ado; de Miranda, Débora Marques; Ashrafi, Kaveh; Romano-Silva, Marco Aurélio

    2014-01-01

    The regulation of energy balance involves an intricate interplay between neural mechanisms that respond to internal and external cues of energy demand and food availability. Compelling data have implicated the neurotransmitter dopamine as an important part of body weight regulation. However, the precise mechanisms through which dopamine regulates energy homeostasis remain poorly understood. Here, we investigate mechanisms through which dopamine modulates energy storage. We showed that dopamine signaling regulates fat reservoirs in Caenorhabditis elegans. We found that the fat reducing effects of dopamine were dependent on dopaminergic receptors and a set of fat oxidation enzymes. Our findings reveal an ancient role for dopaminergic regulation of fat and suggest that dopamine signaling elicits this outcome through cascades that ultimately mobilize peripheral fat depots. PMID:24465759

  3. Surface topography regulates wnt signaling through control of primary cilia structure in mesenchymal stem cells

    NASA Astrophysics Data System (ADS)

    McMurray, R. J.; Wann, A. K. T.; Thompson, C. L.; Connelly, J. T.; Knight, M. M.

    2013-12-01

    The primary cilium regulates cellular signalling including influencing wnt sensitivity by sequestering β-catenin within the ciliary compartment. Topographic regulation of intracellular actin-myosin tension can control stem cell fate of which wnt is an important mediator. We hypothesized that topography influences mesenchymal stem cell (MSC) wnt signaling through the regulation of primary cilia structure and function. MSCs cultured on grooves expressed elongated primary cilia, through reduced actin organization. siRNA inhibition of anterograde intraflagellar transport (IFT88) reduced cilia length and increased active nuclear β-catenin. Conversely, increased primary cilia assembly in MSCs cultured on the grooves was associated with decreased levels of nuclear active β-catenin, axin-2 induction and proliferation, in response to wnt3a. This negative regulation, on grooved topography, was reversed by siRNA to IFT88. This indicates that subtle regulation of IFT and associated cilia structure, tunes the wnt response controlling stem cell differentiation.

  4. Miro1 Regulates Activity-Driven Positioning of Mitochondria within Astrocytic Processes Apposed to Synapses to Regulate Intracellular Calcium Signaling

    PubMed Central

    Stephen, Terri-Leigh; Higgs, Nathalie F.; Sheehan, David F.; Al Awabdh, Sana; López-Doménech, Guillermo; Arancibia-Carcamo, I. Lorena

    2015-01-01

    It is fast emerging that maintaining mitochondrial function is important for regulating astrocyte function, although the specific mechanisms that govern astrocyte mitochondrial trafficking and positioning remain poorly understood. The mitochondrial Rho-GTPase 1 protein (Miro1) regulates mitochondrial trafficking and detachment from the microtubule transport network to control activity-dependent mitochondrial positioning in neurons. However, whether Miro proteins are important for regulating signaling-dependent mitochondrial dynamics in astrocytic processes remains unclear. Using live-cell confocal microscopy of rat organotypic hippocampal slices, we find that enhancing neuronal activity induces transient mitochondrial remodeling in astrocytes, with a concomitant, transient reduction in mitochondrial trafficking, mediated by elevations in intracellular Ca2+. Stimulating neuronal activity also induced mitochondrial confinement within astrocytic processes in close proximity to synapses. Furthermore, we show that the Ca2+-sensing EF-hand domains of Miro1 are important for regulating mitochondrial trafficking in astrocytes and required for activity-driven mitochondrial confinement near synapses. Additionally, activity-dependent mitochondrial positioning by Miro1 reciprocally regulates the levels of intracellular Ca2+ in astrocytic processes. Thus, the regulation of intracellular Ca2+ signaling, dependent on Miro1-mediated mitochondrial positioning, could have important consequences for astrocyte Ca2+ wave propagation, gliotransmission, and ultimately neuronal function. SIGNIFICANCE STATEMENT Mitochondria are key cellular organelles that play important roles in providing cellular energy and buffering intracellular calcium ions. The mechanisms that control mitochondrial distribution within the processes of glial cells called astrocytes and the impact this may have on calcium signaling remains unclear. We show that activation of glutamate receptors or increased neuronal

  5. TGF-β/BMP signaling and other molecular events: regulation of osteoblastogenesis and bone formation

    PubMed Central

    Rahman, Md Shaifur; Akhtar, Naznin; Jamil, Hossen Mohammad; Banik, Rajat Suvra; Asaduzzaman, Sikder M

    2015-01-01

    Transforming growth factor-beta (TGF-β)/bone morphogenetic protein (BMP) plays a fundamental role in the regulation of bone organogenesis through the activation of receptor serine/threonine kinases. Perturbations of TGF-β/BMP activity are almost invariably linked to a wide variety of clinical outcomes, i.e., skeletal, extra skeletal anomalies, autoimmune, cancer, and cardiovascular diseases. Phosphorylation of TGF-β (I/II) or BMP receptors activates intracellular downstream Smads, the transducer of TGF-β/BMP signals. This signaling is modulated by various factors and pathways, including transcription factor Runx2. The signaling network in skeletal development and bone formation is overwhelmingly complex and highly time and space specific. Additive, positive, negative, or synergistic effects are observed when TGF-β/BMP interacts with the pathways of MAPK, Wnt, Hedgehog (Hh), Notch, Akt/mTOR, and miRNA to regulate the effects of BMP-induced signaling in bone dynamics. Accumulating evidence indicates that Runx2 is the key integrator, whereas Hh is a possible modulator, miRNAs are regulators, and β-catenin is a mediator/regulator within the extensive intracellular network. This review focuses on the activation of BMP signaling and interaction with other regulatory components and pathways highlighting the molecular mechanisms regarding TGF-β/BMP function and regulation that could allow understanding the complexity of bone tissue dynamics. PMID:26273537

  6. Ubiquitin-dependent regulation of G protein-coupled receptor trafficking and signaling.

    PubMed

    Marchese, Adriano; Trejo, Joann

    2013-03-01

    G protein-coupled receptors (GPCRs) belong to one of the largest family of signaling receptors in the mammalian genome [1]. GPCRs elicit cellular responses to multiple diverse stimuli and play essential roles in human health and disease. GPCRs have important clinical implications in various diseases and are the targets of approximately 25-50% of all marketed drugs [2,3]. Understanding how GPCRs are regulated is essential to delineating their role in normal physiology and in the pathophysiology of several diseases. Given the vast number and diversity of GPCRs, it is likely that multiple mechanisms exist to regulate GPCR function. While GPCR signaling is typically regulated by desensitization and endocytosis mediated by phosphorylation and β-arrestins, it can also be modulated by ubiquitination. Ubiquitination is emerging an important regulatory process that may have unique roles in governing GPCR trafficking and signaling. Recent studies have revealed a mechanistic link between GPCR phosphorylation, β-arrestins and ubiquitination that may be applicable to some GPCRs but not others. While the function of ubiquitination is generally thought to promote receptor endocytosis and endosomal sorting, recent studies have revealed that ubiquitination also plays an important role in positive regulation of GPCR signaling. Here, we will review recent developments in our understanding of how ubiquitin regulates GPCR endocytic trafficking and how it contributes to signal transduction induced by GPCR activation.

  7. Oxytocin in the regulation of social behaviours in medial amygdala-lesioned mice via the inhibition of the extracellular signal-regulated kinase signalling pathway.

    PubMed

    Wang, Yu; Zhao, Shanshan; Wu, Zhe; Feng, Yu; Zhao, Chuansheng; Zhang, Chaodong

    2015-05-01

    The neuropeptide oxytocin (OXT) has been implicated in the pathophysiology of behavioural deficits among patients with autism spectrum disorder (ASD). However, the molecular mechanisms underlying its role in ASD remain unclear. In the present study, a murine model with ASD-like phenotypes was induced by intra-medial amygdala injection of N-methyl-d-aspartate, and it was used to investigate the role of OXT in behaviour regulation. Behavioural tests were performed to verify the ASD-like phenotypes of N-methyl-d-aspartate-treated mice, and the results showed that mice with bilateral medial amygdala lesions presented significant behavioural deficits, including impaired learning and memory and increased anxiety and depression. We also observed a notably decreased level of OXT in both the plasma and the hypothalamus of medial amygdala-lesioned mice, and the extracellular signal-regulated kinase (ERK) was activated. Further studies demonstrated that the administration of OXT alleviated ASD-like symptoms and significantly inhibited phosphorylation of ERK; the inhibitory effect was similar to that of U0126, an ERK signalling inhibitor. In addition, OXT administration modulated the expression of downstream proteins of the ERK signalling pathway, such as cyclic adenosine monophosphate response element binding and c-fos. Taken together, our data indicate that OXT plays an important role in ameliorating behavioural deficits in an ASD-like mouse model, which was mediated by inhibiting the ERK signalling pathway and its downstream proteins.

  8. Real time moving object detection using motor signal and depth map for robot car

    NASA Astrophysics Data System (ADS)

    Wu, Hao; Siu, Wan-Chi

    2013-12-01

    Moving object detection from a moving camera is a fundamental task in many applications. For the moving robot car vision, the background movement is 3D motion structure in nature. In this situation, the conventional moving object detection algorithm cannot be use to handle the 3D background modeling effectively and efficiently. In this paper, a novel scheme is proposed by utilizing the motor control signal and depth map obtained from a stereo camera to model the perspective transform matrix between different frames under a moving camera. In our approach, the coordinate relationship between frames during camera moving is modeled by a perspective transform matrix which is obtained by using current motor control signals and the pixel depth value. Hence, the relationship between a static background pixel and the moving foreground corresponding to the camera motion can be related by a perspective matrix. To enhance the robustness of classification, we allowed a tolerance range during the perspective transform matrix prediction and used multi-reference frames to classify the pixel on current frame. The proposed scheme has been found to be able to detect moving objects for our moving robot car efficiently. Different from conventional approaches, our method can model the moving background in 3D structure, without online model training. More importantly, the computational complexity and memory requirement are low making it possible to implement this scheme in real-time, which is even valuable for a robot vision system.

  9. The scaffold protein MUPP1 regulates odorant-mediated signaling in olfactory sensory neurons.

    PubMed

    Baumgart, Sabrina; Jansen, Fabian; Bintig, Willem; Kalbe, Benjamin; Herrmann, Christian; Klumpers, Fabian; Köster, S David; Scholz, Paul; Rasche, Sebastian; Dooley, Ruth; Metzler-Nolte, Nils; Spehr, Marc; Hatt, Hanns; Neuhaus, Eva M

    2014-06-01

    The olfactory signal transduction cascade transforms odor information into electrical signals by a cAMP-based amplification mechanism. The mechanisms underlying the very precise temporal and spatial organization of the relevant signaling components remains poorly understood. Here, we identify, using co-immunoprecipitation experiments, a macromolecular assembly of signal transduction components in mouse olfactory neurons, organized through MUPP1. Disruption of the PDZ signaling complex, through use of an inhibitory peptide, strongly impaired odor responses and changed the activation kinetics of olfactory sensory neurons. In addition, our experiments demonstrate that termination of the response is dependent on PDZ-based scaffolding. These findings provide new insights into the functional organization, and regulation, of olfactory signal transduction. PMID:24652834

  10. Role of Wnt and Notch signaling in regulating hair cell regeneration in the cochlea.

    PubMed

    Waqas, Muhammad; Zhang, Shasha; He, Zuhong; Tang, Mingliang; Chai, Renjie

    2016-09-01

    Sensory hair cells in the inner ear are responsible for sound recognition. Damage to hair cells in adult mammals causes permanent hearing impairment because these cells cannot regenerate. By contrast, newborn mammals possess limited regenerative capacity because of the active participation of various signaling pathways, including Wnt and Notch signaling. The Wnt and Notch pathways are highly sophisticated and conserved signaling pathways that control multiple cellular events necessary for the formation of sensory hair cells. Both signaling pathways allow resident supporting cells to regenerate hair cells in the neonatal cochlea. In this regard, Wnt and Notch signaling has gained increased research attention in hair cell regeneration. This review presents the current understanding of the Wnt and Notch signaling pathways in the auditory portion of the inner ear and discusses the possibilities of controlling these pathways with the hair cell fate determiner Atoh1 to regulate hair cell regeneration in the mammalian cochlea.

  11. Role of Wnt and Notch signaling in regulating hair cell regeneration in the cochlea.

    PubMed

    Waqas, Muhammad; Zhang, Shasha; He, Zuhong; Tang, Mingliang; Chai, Renjie

    2016-09-01

    Sensory hair cells in the inner ear are responsible for sound recognition. Damage to hair cells in adult mammals causes permanent hearing impairment because these cells cannot regenerate. By contrast, newborn mammals possess limited regenerative capacity because of the active participation of various signaling pathways, including Wnt and Notch signaling. The Wnt and Notch pathways are highly sophisticated and conserved signaling pathways that control multiple cellular events necessary for the formation of sensory hair cells. Both signaling pathways allow resident supporting cells to regenerate hair cells in the neonatal cochlea. In this regard, Wnt and Notch signaling has gained increased research attention in hair cell regeneration. This review presents the current understanding of the Wnt and Notch signaling pathways in the auditory portion of the inner ear and discusses the possibilities of controlling these pathways with the hair cell fate determiner Atoh1 to regulate hair cell regeneration in the mammalian cochlea. PMID:27527363

  12. Chemical biology tools for regulating RAS signaling complexity in space and time.

    PubMed

    van Hattum, Hilde; Waldmann, Herbert

    2014-09-18

    Rat sarcoma (RAS) family members are small GTPases that control a number of signaling pathways important for normal cellular proliferation. Therefore, it is no surprise that a significant portion of human tumors express constitutively active mutated RAS proteins, which leads to deregulation of RAS signaling pathways, resulting in pathological perturbations of cell growth and death. Although the molecular details of RAS signaling cascades are well understood, there is still a largely unmet need for small molecule probes to control RAS signaling in space and time. More broadly, given the prevalence of mutated RAS in cancer, the need to translate the insights obtained from using small molecule probes into clinically useful drugs is also significant. In this review, we introduce RAS proteins and the signaling pathways they are involved in, and discuss some of the innovative chemical biology approaches to regulate RAS signaling, which include the exploitation of newly identified binding pockets, covalent inhibitors for mutated RAS, and RAS localization impairment.

  13. Wnt signaling regulates multipolar-to-bipolar transition of migrating neurons in the cerebral cortex.

    PubMed

    Boitard, Michael; Bocchi, Riccardo; Egervari, Kristof; Petrenko, Volodymyr; Viale, Beatrice; Gremaud, Stéphane; Zgraggen, Eloisa; Salmon, Patrick; Kiss, Jozsef Z

    2015-03-01

    The precise timing of pyramidal cell migration from the ventricular germinal zone to the cortical plate is essential for establishing cortical layers, and migration errors can lead to neurodevelopmental disorders underlying psychiatric and neurological diseases. Here, we report that Wnt canonical as well as non-canonical signaling is active in pyramidal precursors during radial migration. We demonstrate using constitutive and conditional genetic strategies that transient downregulation of canonical Wnt/β-catenin signaling during the multipolar stage plays a critical role in polarizing and orienting cells for radial migration. In addition, we show that reduced canonical Wnt signaling is triggered cell autonomously by time-dependent expression of Wnt5A and activation of non-canonical signaling. We identify ephrin-B1 as a canonical Wnt-signaling-regulated target in control of the multipolar-to-bipolar switch. These findings highlight the critical role of Wnt signaling activity in neuronal positioning during cortical development. PMID:25732825

  14. Wnt signaling regulates multipolar-to-bipolar transition of migrating neurons in the cerebral cortex.

    PubMed

    Boitard, Michael; Bocchi, Riccardo; Egervari, Kristof; Petrenko, Volodymyr; Viale, Beatrice; Gremaud, Stéphane; Zgraggen, Eloisa; Salmon, Patrick; Kiss, Jozsef Z

    2015-03-01

    The precise timing of pyramidal cell migration from the ventricular germinal zone to the cortical plate is essential for establishing cortical layers, and migration errors can lead to neurodevelopmental disorders underlying psychiatric and neurological diseases. Here, we report that Wnt canonical as well as non-canonical signaling is active in pyramidal precursors during radial migration. We demonstrate using constitutive and conditional genetic strategies that transient downregulation of canonical Wnt/β-catenin signaling during the multipolar stage plays a critical role in polarizing and orienting cells for radial migration. In addition, we show that reduced canonical Wnt signaling is triggered cell autonomously by time-dependent expression of Wnt5A and activation of non-canonical signaling. We identify ephrin-B1 as a canonical Wnt-signaling-regulated target in control of the multipolar-to-bipolar switch. These findings highlight the critical role of Wnt signaling activity in neuronal positioning during cortical development.

  15. A study on the buffeting aberrance regulation of TDICCD mapping camera

    NASA Astrophysics Data System (ADS)

    Bai, Zhe; Ma, Zhen; Zhang, Boheng

    2011-08-01

    In this paper, the fundamental of the TDICCD mapping camera is introduced, and the influence of the satellite buffeting on the image quality of the TDICCD camera is analyzed. In order to reduce the influence, a regulated resolution is put forward. Compared with the traditional TDICCD mapping camera, a special TDICCD focal plane which several TDICCD devices splited joint end to end is designed. A great deal of information are captured through the focal plane, and a mathematical model is established to analyze the data information. Then the results are feed back to the satellite, and the attitude of the satellite is actively regulated in real time. Finally, make experiments and simulation to validate it. The experiment result indicate that the design is valid.

  16. Self-regulation and cross-regulation of pattern-recognition receptor signalling in health and disease.

    PubMed

    Cao, Xuetao

    2016-01-01

    In the initiation of innate immune responses against pathogens, pattern-recognition receptors (PRRs) have an essential role in recognizing specific components of microorganisms and triggering responses that eliminate the invading microorganisms. However, inappropriate activation of PRRs can lead to prolonged inflammation and even to autoimmune and inflammatory diseases. Thus, PRR-triggered responses are regulated through the degradation or translocation of the innate receptors themselves and through the involvement of intracellular regulators or amplifiers. In addition, a complex interplay between PRRs and/or other immune pathways finely tunes the outcome of host immune defence responses. In this Review, I describe many of the numerous distinct mechanisms for the self-regulation and cross-regulation of innate immune receptor signalling.

  17. Mapping.

    ERIC Educational Resources Information Center

    Kinney, Douglas M.; McIntosh, Willard L.

    1979-01-01

    The area of geological mapping in the United States in 1978 increased greatly over that reported in 1977; state geological maps were added for California, Idaho, Nevada, and Alaska last year. (Author/BB)

  18. ROP GTPase-mediated auxin signaling regulates pavement cell interdigitation in Arabidopsis thaliana.

    PubMed

    Lin, Deshu; Ren, Huibo; Fu, Ying

    2015-01-01

    In multicellular plant organs, cell shape formation depends on molecular switches to transduce developmental or environmental signals and to coordinate cell-to-cell communication. Plants have a specific subfamily of the Rho GTPase family, usually called Rho of Plants (ROP), which serve as a critical signal transducer involved in many cellular processes. In the last decade, important advances in the ROP-mediated regulation of plant cell morphogenesis have been made by using Arabidopsis thaliana leaf and cotyledon pavement cells. Especially, the auxin-ROP signaling networks have been demonstrated to control interdigitated growth of pavement cells to form jigsaw-puzzle shapes. Here, we review findings related to the discovery of this novel auxin-signaling mechanism at the cell surface. This signaling pathway is to a large extent independent of the well-known Transport Inhibitor Response (TIR)-Auxin Signaling F-Box (AFB) pathway, and instead requires Auxin Binding Protein 1 (ABP1) interaction with the plasma membrane-localized, transmembrane kinase (TMK) receptor-like kinase to regulate ROP proteins. Once activated, ROP influences cytoskeletal organization and inhibits endocytosis of the auxin transporter PIN1. The present review focuses on ROP signaling and its self-organizing feature allowing ROP proteins to serve as a bustling signal decoder and integrator for plant cell morphogenesis.

  19. Signaling, Regulation, and Specificity of the Type II p21-activated Kinases*

    PubMed Central

    Ha, Byung Hak; Morse, Elizabeth M.; Turk, Benjamin E.; Boggon, Titus J.

    2015-01-01

    The p21-activated kinases (PAKs) are a family of six serine/threonine kinases that act as key effectors of RHO family GTPases in mammalian cells. PAKs are subdivided into two groups: type I PAKs (PAK1, PAK2, and PAK3) and type II PAKs (PAK4, PAK5, and PAK6). Although these groups are involved in common signaling pathways, recent work indicates that the two groups have distinct modes of regulation and have both unique and common substrates. Here, we review recent insights into the molecular level details that govern regulation of type II PAK signaling. We also consider mechanisms by which signal transduction is regulated at the level of substrate specificity. Finally, we discuss the implications of these studies for clinical targeting of these kinases. PMID:25855792

  20. PPM1A Regulates Antiviral Signaling by Antagonizing TBK1-Mediated STING Phosphorylation and Aggregation

    PubMed Central

    Li, Zexing; Liu, Ge; Sun, Liwei; Teng, Yan; Guo, Xuejiang; Jia, Jianhang; Sha, Jiahao; Yang, Xiao; Chen, Dahua; Sun, Qinmiao

    2015-01-01

    Stimulator of interferon genes (STING, also known as MITA and ERIS) is critical in protecting the host against DNA pathogen invasion. However, the molecular mechanism underlying the regulation of STING remains unclear. Here, we show that PPM1A negatively regulates antiviral signaling by targeting STING in its phosphatase activity-dependent manner, and in a line with this, PPM1A catalytically dephosphorylates STING and TBK1 in vitro. Importantly, we provide evidence that whereas TBK1 promotes STING aggregation in a phosphorylation-dependent manner, PPM1A antagonizes STING aggregation by dephosphorylating both STING and TBK1, emphasizing that phosphorylation is crucial for the efficient activation of STING. Our findings demonstrate a novel regulatory circuit in which STING and TBK1 reciprocally regulate each other to enable efficient antiviral signaling activation, and PPM1A dephosphorylates STING and TBK1, thereby balancing this antiviral signal transduction. PMID:25815785

  1. Orphan receptor IL-17RD regulates Toll-like receptor signalling via SEFIR/TIR interactions.

    PubMed

    Mellett, Mark; Atzei, Paola; Bergin, Ronan; Horgan, Alan; Floss, Thomas; Wurst, Wolfgang; Callanan, John J; Moynagh, Paul N

    2015-01-01

    Receptor families of the innate immune response engage in 'cross-talk' to tailor optimal immune responses against invading pathogens. However, these responses are subject to multiple levels of regulation to keep in check aberrant inflammatory signals. Here, we describe a role for the orphan receptor interleukin-17 receptor D (IL-17RD) in negatively regulating Toll-like receptor (TLR)-induced responses. Deficiency of IL-17RD expression in cells leads to enhanced pro-inflammatory signalling and gene expression in response to TLR stimulation, and Il17rd(-/-) mice are more susceptible to TLR-induced septic shock. We demonstrate that the intracellular Sef/IL-17R (SEFIR) domain of IL-17RD targets TIR adaptor proteins to inhibit TLR downstream signalling thus revealing a paradigm involving cross-regulation of members of the IL-17R and TLR families.

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

    PubMed Central

    Tonks, Nicholas K.

    2013-01-01

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

  3. Neuronal Regulation of Schwann Cell Mitochondrial Ca(2+) Signaling during Myelination.

    PubMed

    Ino, Daisuke; Sagara, Hiroshi; Suzuki, Junji; Kanemaru, Kazunori; Okubo, Yohei; Iino, Masamitsu

    2015-09-29

    Schwann cells (SCs) myelinate peripheral neurons to promote the rapid conduction of action potentials, and the process of myelination is known to be regulated by signals from axons to SCs. Given that SC mitochondria are one of the potential regulators of myelination, we investigated whether SC mitochondria are regulated by axonal signaling. Here, we show a purinergic mechanism that sends information from neurons to SC mitochondria during myelination. Our results show that electrical stimulation of rat sciatic nerve increases extracellular ATP levels enough to activate purinergic receptors. Indeed, electrical stimulation of sciatic nerves induces Ca(2+) increases in the cytosol and the mitochondrial matrix of surrounding SCs via purinergic receptor activation. Chronic suppression of this pathway during active myelination suppressed the longitudinal and radial development of myelinating SCs and caused hypomyelination. These results demonstrate a neuron-to-SC mitochondria signaling, which is likely to have an important role in proper myelination.

  4. Signalling mucin Msb2 Regulates adaptation to thermal stress in Candida albicans

    PubMed Central

    Saraswat, Darpan; Kumar, Rohitashw; Pande, Tanaya; Edgerton, Mira; Cullen, Paul J.

    2016-01-01

    Summary Temperature is a potent inducer of fungal dimorphism. Multiple signalling pathways control the response to growth at high temperature, but the sensors that regulate these pathways are poorly defined. We show here that the signalling mucin Msb2 is a global regulator of temperature stress in the fungal pathogen Candida albicans. Msb2 was required for survival and hyphae formation at 42°C. The cytoplasmic signalling domain of Msb2 regulated temperature-dependent activation of the CEK mitogen activated proteins kinase (MAPK) pathway. The extracellular glycosylated domain of Msb2 (100–900 amino acid residues) had a new and unexpected role in regulating the protein kinase C (PKC) pathway. Msb2 also regulated temperature-dependent induction of genes encoding regulators and targets of the unfolded protein response (UPR), which is a protein quality control (QC) pathway in the endoplasmic reticulum that controls protein folding/degradation in response to high temperature and other stresses. The heat shock protein and cell wall component Ssa1 was also required for hyphae formation and survival at 42° C and regulated the CEK and PKC pathways. PMID:26749104

  5. Diverse Regulation of Temperature Sensation by Trimeric G-Protein Signaling in Caenorhabditis elegans

    PubMed Central

    Ujisawa, Tomoyo; Ohta, Akane; Uda-Yagi, Misato

    2016-01-01

    Temperature sensation by the nervous system is essential for life and proliferation of animals. The molecular-physiological mechanisms underlying temperature signaling have not been fully elucidated. We show here that diverse regulatory machinery underlies temperature sensation through trimeric G-protein signaling in the nematode Caenorhabditis elegans. Molecular-genetic studies demonstrated that cold tolerance is regulated by additive functions of three Gα proteins in a temperature-sensing neuron, ASJ, which is also known to be a light-sensing neuron. Optical recording of calcium concentration in ASJ upon temperature-changes demonstrated that three Gα proteins act in different aspects of temperature signaling. Calcium concentration changes in ASJ upon temperature change were unexpectedly decreased in a mutant defective in phosphodiesterase, which is well known as a negative regulator of calcium increase. Together, these data demonstrate commonalities and differences in the molecular components concerned with light and temperature signaling in a single sensory neuron. PMID:27788246

  6. Canonical Wnt signalling regulates epithelial patterning by modulating levels of laminins in zebrafish appendages

    PubMed Central

    Nagendran, Monica; Arora, Prateek; Gori, Payal; Mulay, Aditya; Ray, Shinjini; Jacob, Tressa; Sonawane, Mahendra

    2015-01-01

    The patterning and morphogenesis of body appendages – such as limbs and fins – is orchestrated by the activities of several developmental pathways. Wnt signalling is essential for the induction of limbs. However, it is unclear whether a canonical Wnt signalling gradient exists and regulates the patterning of epithelium in vertebrate appendages. Using an evolutionarily old appendage – the median fin in zebrafish – as a model, we show that the fin epithelium exhibits graded changes in cellular morphology along the proximo-distal axis. This epithelial pattern is strictly correlated with the gradient of canonical Wnt signalling activity. By combining genetic analyses with cellular imaging, we show that canonical Wnt signalling regulates epithelial cell morphology by modulating the levels of laminins, which are extracellular matrix components. We have unravelled a hitherto unknown mechanism involved in epithelial patterning, which is also conserved in the pectoral fins – evolutionarily recent appendages that are homologous to tetrapod limbs. PMID:25519245

  7. Recent advances in understanding carotenoid-derived signaling molecules in regulating plant growth and development

    PubMed Central

    Tian, Li

    2015-01-01

    Carotenoids (C40) are synthesized in plastids and perform numerous important functions in these organelles. In addition, carotenoids can be processed into smaller signaling molecules that regulate various phases of the plant’s life cycle. Besides the relatively well-studied phytohormones abscisic acid (ABA) and strigolactones (SLs), additional carotenoid-derived signaling molecules have been discovered and shown to regulate plant growth and development. As a few excellent reviews summarized recent research on ABA and SLs, this mini review will focus on progress made on identification and characterization of the emerging carotenoid-derived signals. Overall, a better understanding of carotenoid-derived signaling molecules has immediate applications in improving plant biomass production which in turn will have far reaching impacts on providing food, feed, and fuel for the growing world population. PMID:26442092

  8. Nerve Growth Factor Regulates Transient Receptor Potential Vanilloid 2 via Extracellular Signal-Regulated Kinase Signaling To Enhance Neurite Outgrowth in Developing Neurons

    PubMed Central

    Cohen, Matthew R.; Johnson, William M.; Pilat, Jennifer M.; Kiselar, Janna; DeFrancesco-Lisowitz, Alicia; Zigmond, Richard E.

    2015-01-01

    Neurite outgrowth is key to the formation of functional circuits during neuronal development. Neurotrophins, including nerve growth factor (NGF), increase neurite outgrowth in part by altering the function and expression of Ca2+-permeable cation channels. Here we report that transient receptor potential vanilloid 2 (TRPV2) is an intracellular Ca2+-permeable TRPV channel upregulated by NGF via the mitogen-activated protein kinase (MAPK) signaling pathway to augment neurite outgrowth. TRPV2 colocalized with Rab7, a late endosome protein, in addition to TrkA and activated extracellular signal-regulated kinase (ERK) in neurites, indicating that the channel is closely associated with signaling endosomes. In line with these results, we showed that TRPV2 acts as an ERK substrate and identified the motifs necessary for phosphorylation of TRPV2 by ERK. Furthermore, neurite length, TRPV2 expression, and TRPV2-mediated Ca2+ signals were reduced by mutagenesis of these key ERK phosphorylation sites. Based on these findings, we identified a previously uncharacterized mechanism by which ERK controls TRPV2-mediated Ca2+ signals in developing neurons and further establish TRPV2 as a critical intracellular ion channel in neuronal function. PMID:26416880

  9. Role played by Disabled-2 in albumin induced MAP Kinase signalling

    SciTech Connect

    Diwakar, Ramaswamy Pearson, Alexander L.; Colville-Nash, Paul; Baines, Deborah L.; Dockrell, Mark E.C.

    2008-02-15

    Albumin has been shown to activate the mitogen activated protein kinase (MAPK) pathway in proximal tubular cells (PTECs) of the kidney. Megalin, the putative receptor for albumin has potential signalling properties. However, the mechanisms by which megalin signals are unclear. The adaptor phosphoprotein Disabled-2 (Dab2) is known to interact with the cytoplasmic tail of megalin and may be involved in albumin-mediated MAPK signalling. In this study, we investigated the role of Dab2 in albumin-mediated MAPK signalling and further studied the role of Dab2 in albumin-induced TGF{beta}-1 secretion, a MAPK dependent event. We used RNA interference to knockdown Dab2 protein abundance in HKC-8 cells a model of human PTECs. Albumin activated ERK1,2 and Elk-1 in a MEK-1 dependent manner and resulted in secretion of TGF{beta}-1. In the absence of albumin, knockdown of Dab2 resulted in a trend towards increase in pERK1,2 consistent with its putative role as an inhibitor of cell proliferation. However albumin-induced ERK1,2 activation was completely abolished by Dab2 knockdown. Dab2 knockdown did not however result in inhibition of albumin-induced TGF{beta}-1 secretion. These results suggest that Dab2 is a ligand dependent bi-directional regulator of ERK1,2 activity by demonstrating that in addition to its more traditional role as an inhibitor of ERK1,2 it may also activate ERK1,2.

  10. An insulin signaling feedback loop regulates pancreas progenitor cell differentiation during islet development and regeneration

    PubMed Central

    Ye, Lihua; Robertson, Morgan A.; Mastracci, Teresa L.; Anderson, Ryan M.

    2016-01-01

    As one of the key nutrient sensors, insulin signaling plays an important role in integrating environmental energy cues with organism growth. In adult organisms, relative insufficiency of insulin signaling induces compensatory expansion of insulin-secreting pancreatic beta (β) cells. However, little is known about how insulin signaling feedback might influence neogenesis of β cells during embryonic development. Using genetic approaches and a unique cell transplantation system in developing zebrafish, we have uncovered a novel role for insulin signaling in the negative regulation of pancreatic progenitor cell differentiation. Blocking insulin signaling in the pancreatic progenitors hastened the expression of the essential β cell genes insulin and pdx1, and promoted β cell fate at the expense of alpha cell fate. In addition, loss of insulin signaling promoted β cell regeneration and destabilization of alpha cell character. These data indicate that insulin signaling constitutes a tunable mechanism for β cell compensatory plasticity during early development. Moreover, using a novel blastomere-to-larva transplantation strategy, we found that loss of insulin signaling in endoderm-committed blastomeres drove their differentiation into β cells. Furthermore, the extent of this differentiation was dependent on the function of the β cell mass in the host. Altogether, our results indicate that modulation of insulin signaling will be crucial for the development of β cell restoration therapies for diabetics; further clarification of the mechanisms of insulin signaling in β cell progenitors will reveal therapeutic targets for both in vivo and in vitro β cell generation. PMID:26658317

  11. An insulin signaling feedback loop regulates pancreas progenitor cell differentiation during islet development and regeneration.

    PubMed

    Ye, Lihua; Robertson, Morgan A; Mastracci, Teresa L; Anderson, Ryan M

    2016-01-15

    As one of the key nutrient sensors, insulin signaling plays an important role in integrating environmental energy cues with organism growth. In adult organisms, relative insufficiency of insulin signaling induces compensatory expansion of insulin-secreting pancreatic beta (β) cells. However, little is known about how insulin signaling feedback might influence neogenesis of β cells during embryonic development. Using genetic approaches and a unique cell transplantation system in developing zebrafish, we have uncovered a novel role for insulin signaling in the negative regulation of pancreatic progenitor cell differentiation. Blocking insulin signaling in the pancreatic progenitors hastened the expression of the essential β cell genes insulin and pdx1, and promoted β cell fate at the expense of alpha cell fate. In addition, loss of insulin signaling promoted β cell regeneration and destabilization of alpha cell character. These data indicate that insulin signaling constitutes a tunable mechanism for β cell compensatory plasticity during early development. Moreover, using a novel blastomere-to-larva transplantation strategy, we found that loss of insulin signaling in endoderm-committed blastomeres drove their differentiation into β cells. Furthermore, the extent of this differentiation was dependent on the function of the β cell mass in the host. Altogether, our results indicate that modulation of insulin signaling will be crucial for the development of β cell restoration therapies for diabetics; further clarification of the mechanisms of insulin signaling in β cell progenitors will reveal therapeutic targets for both in vivo and in vitro β cell generation. PMID:26658317

  12. Dendritic cell maturation requires STAT1 and is under feedback regulation by suppressors of cytokine signaling.

    PubMed

    Jackson, Sharon H; Yu, Cheng-Rong; Mahdi, Rashid M; Ebong, Samuel; Egwuagu, Charles E

    2004-02-15

    In this study we show that activation of STAT pathways is developmentally regulated and plays a role in dendritic cell (DC) differentiation and maturation. The STAT6 signaling pathway is constitutively activated in immature DC (iDC) and declines as iDCs differentiate into mature DCs (mDCs). However, down-regulation of this pathway during DC differentiation is accompanied by dramatic induction of suppressors of cytokine signaling 1 (SOCS1), SOCS2, SOCS3, and cytokine-induced Src homology 2-containing protein expression, suggesting that inhibition of STAT6 signaling may be required for DC maturation. In contrast, STAT1 signaling is most robust in mDCs and is not inhibited by the up-regulated SOCS proteins, indicating that STAT1 and STAT6 pathways are distinctly regulated in maturing DC. Furthermore, optimal activation of STAT1 during DC maturation requires both IL-4 and GM-CSF, suggesting that synergistic effects of both cytokines may in part provide the requisite STAT1 signaling intensity for DC maturation. Analyses of STAT1(-/-) DCs reveal a role for STAT1 in repressing CD86 expression in precursor DCs and up-regulating CD40, CD11c, and SOCS1 expression in mDCs. We further show that SOCS proteins are differentially induced by IL-4 and GM-CSF in DCs. SOCS1 is primarily induced by IL-4 through a STAT1-dependent mechanism, whereas SOCS3 is induced mainly by GM-CSF. Taken together, these results suggest that cytokine-induced maturation of DCs is under feedback regulation by SOCS proteins and that the switch from constitutive activation of the STAT6 pathway in iDCs to predominant use of STAT1 signals in mDC is mediated in part by STAT1-induced SOCS expression.

  13. Atlas of Cancer Signalling Network: a systems biology resource for integrative analysis of cancer data with Google Maps

    PubMed Central

    Kuperstein, I; Bonnet, E; Nguyen, H-A; Cohen, D; Viara, E; Grieco, L; Fourquet, S; Calzone, L; Russo, C; Kondratova, M; Dutreix, M; Barillot, E; Zinovyev, A

    2015-01-01

    Cancerogenesis is driven by mutations leading to aberrant functioning of a complex network of molecular interactions and simultaneously affecting multiple cellular functions. Therefore, the successful application of bioinformatics and systems biology methods for analysis of high-throughput data in cancer research heavily depends on availability of global and detailed reconstructions of signalling networks amenable for computational analysis. We present here the Atlas of Cancer Signalling Network (ACSN), an interactive and comprehensive map of molecular mechanisms implicated in cancer. The resource includes tools for map navigation, visualization and analysis of molecular data in the context of signalling network maps. Constructing and updating ACSN involves careful manual curation of molecular biology literature and participation of experts in the corresponding fields. The cancer-oriented content of ACSN is completely original and covers major mechanisms involved in cancer progression, including DNA repair, cell survival, apoptosis, cell cycle, EMT and cell motility. Cell signalling mechanisms are depicted in detail, together creating a seamless ‘geographic-like' map of molecular interactions frequently deregulated in cancer. The map is browsable using NaviCell web interface using the Google Maps engine and semantic zooming principle. The associated web-blog provides a forum for commenting and curating the ACSN content. ACSN allows uploading heterogeneous omics data from users on top of the maps for visualization and performing functional analyses. We suggest several scenarios for ACSN application in cancer research, particularly for visualizing high-throughput data, starting from small interfering RNA-based screening results or mutation frequencies to innovative ways of exploring transcriptomes and phosphoproteomes. Integration and analysis of these data in the context of ACSN may help interpret their biological significance and formulate mechanistic hypotheses

  14. Atlas of Cancer Signalling Network: a systems biology resource for integrative analysis of cancer data with Google Maps.

    PubMed

    Kuperstein, I; Bonnet, E; Nguyen, H-A; Cohen, D; Viara, E; Grieco, L; Fourquet, S; Calzone, L; Russo, C; Kondratova, M; Dutreix, M; Barillot, E; Zinovyev, A

    2015-01-01

    Cancerogenesis is driven by mutations leading to aberrant functioning of a complex network of molecular interactions and simultaneously affecting multiple cellular functions. Therefore, the successful application of bioinformatics and systems biology methods for analysis of high-throughput data in cancer research heavily depends on availability of global and detailed reconstructions of signalling networks amenable for computational analysis. We present here the Atlas of Cancer Signalling Network (ACSN), an interactive and comprehensive map of molecular mechanisms implicated in cancer. The resource includes tools for map navigation, visualization and analysis of molecular data in the context of signalling network maps. Constructing and updating ACSN involves careful manual curation of molecular biology literature and participation of experts in the corresponding fields. The cancer-oriented content of ACSN is completely original and covers major mechanisms involved in cancer progression, including DNA repair, cell survival, apoptosis, cell cycle, EMT and cell motility. Cell signalling mechanisms are depicted in detail, together creating a seamless 'geographic-like' map of molecular interactions frequently deregulated in cancer. The map is browsable using NaviCell web interface using the Google Maps engine and semantic zooming principle. The associated web-blog provides a forum for commenting and curating the ACSN content. ACSN allows uploading heterogeneous omics data from users on top of the maps for visualization and performing functional analyses. We suggest several scenarios for ACSN application in cancer research, particularly for visualizing high-throughput data, starting from small interfering RNA-based screening results or mutation frequencies to innovative ways of exploring transcriptomes and phosphoproteomes. Integration and analysis of these data in the context of ACSN may help interpret their biological significance and formulate mechanistic hypotheses

  15. PKA-CREB-BDNF signaling regulated long lasting antidepressant activities of Yueju but not ketamine

    PubMed Central

    Xue, Wenda; Wang, Wei; Gong, Tong; Zhang, Hailou; Tao, Weiwei; Xue, Lihong; Sun, Yan; Wang, Fushun; Chen, Gang

    2016-01-01

    Yueju confers antidepressant effects in a rapid and long-lasting manner, similar to ketamine. CREB (cAMP-response element binding protein) signaling is implicated in depression pathology and antidepressant responses. However, the role of CREB and associated brain derived neurotrophic factor (BDNF) signaling in rapid and long-lasting antidepressant effects remains unclear. Here, we demonstrated that ICR and Kunming strain mice conferred antidepressant responses lasting for 1 and 5 days, respectively, following a single dose of Yueju. One day post Yueju in Kunming but not ICR strain mice, expression of total and phosphorylated CREB, as well as the CREB signaling activator, PKA (protein kinase A) was up-regulated in the hippocampus. Although BDNF gene expression increased at 3 hours in both strains, it remained up-regulated at 1 day only in Kunming mice. Ketamine showed similar strain-dependent behavioral effects. However, blockade of PKA/CREB signaling blunted the antidepressant effects and reversed the up-regulation of BDNF gene expression by Yueju, but not ketamine. Conversely, blockade of mammalian target of rapamycin signaling led to opposite effects. Taken altogether, prolonged transcriptional up-regulation of hippocampal BDNF may account for the stain-dependent enduring antidepressant responses to Yueju and ketamine, but it was mediated via PKA/CREB pathway only for Yueju. PMID:27197752

  16. [Mechanism of stomatal regulation by root sourced signaling and its agricultural signficance].

    PubMed

    Guo, Anhong; Li, Zhaoxiang; Liu, Gengshan; Yang, Yuanyan; An, Shunqing

    2004-06-01

    Under soil drought condition, root sourced signal abcisic acid (ABA) plays an important role in the long distance signaling process, and can be a measurement of soil water availability. ABA is also an effective stomatal closing agent, and ac