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Sample records for signal regulating map

  1. 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.

  2. Cellular context–mediated Akt dynamics regulates MAP kinase signaling thresholds during angiogenesis

    PubMed Central

    Hellesøy, Monica; Lorens, James B.

    2015-01-01

    The formation of new blood vessels by sprouting angiogenesis is tightly regulated by contextual cues that affect angiogeneic growth factor signaling. Both constitutive activation and loss of Akt kinase activity in endothelial cells impair angiogenesis, suggesting that Akt dynamics mediates contextual microenvironmental regulation. We explored the temporal regulation of Akt in endothelial cells during formation of capillary-like networks induced by cell–cell contact with vascular smooth muscle cells (vSMCs) and vSMC-associated VEGF. Expression of constitutively active Akt1 strongly inhibited network formation, whereas hemiphosphorylated Akt1 epi-alleles with reduced kinase activity had an intermediate inhibitory effect. Conversely, inhibition of Akt signaling did not affect endothelial cell migration or morphogenesis in vSMC cocultures that generate capillary-like structures. We found that endothelial Akt activity is transiently blocked by proteasomal degradation in the presence of SMCs during the initial phase of capillary-like structure formation. Suppressed Akt activity corresponded to the increased endothelial MAP kinase signaling that was required for angiogenic endothelial morphogenesis. These results reveal a regulatory principle by which cellular context regulates Akt protein dynamics, which determines MAP kinase signaling thresholds necessary drive a morphogenetic program during angiogenesis. PMID:26023089

  3. A MAP4 kinase related to Ste20 is a nutrient-sensitive regulator of mTOR signalling

    PubMed Central

    Findlay, Greg M.; Yan, Lijun; Procter, Julia; Mieulet, Virginie; Lamb, Richard F.

    2007-01-01

    The mTOR (mammalian target of rapamycin) signalling pathway is a key regulator of cell growth and is controlled by growth factors and nutrients such as amino acids. Although signalling pathways from growth factor receptors to mTOR have been elucidated, the pathways mediating signalling by nutrients are poorly characterized. Through a screen for protein kinases active in the mTOR signalling pathway in Drosophila we have identified a Ste20 family member (MAP4K3) that is required for maximal S6K (S6 kinase)/4E-BP1 [eIF4E (eukaryotic initiation factor 4E)-binding protein 1] phosphorylation and regulates cell growth. Importantly, MAP4K3 activity is regulated by amino acids, but not the growth factor insulin and is not regulated by the mTORC1 inhibitor rapamycin. Our results therefore suggest a model whereby nutrients signal to mTORC1 via activation of MAP4K3. PMID:17253963

  4. TNF and MAP kinase signaling pathways

    PubMed Central

    Sabio, Guadalupe; Davis, Roger J.

    2014-01-01

    The binding of tumor necrosis factor α (TNFα) to cell surface receptors engages multiple signal transduction pathways, including three groups of mitogen-activated protein (MAP) kinases: extracellular-signal-regulated kinases (ERKs); the cJun NH2-terminal kinases (JNKs); and the p38 MAP kinases. These MAP kinase signalling pathways induce a secondary response by increasing the expression of several inflammatory cytokines (including TNFα) that contribute to the biological activity of TNFα. MAP kinases therefore function both upstream and down-stream of signalling by TNFα receptors. Here we review mechanisms that mediate these actions of MAP kinases during the response to TNFα. PMID:24647229

  5. 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.

  6. 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

  7. Nitric oxide affects ERK signaling through down-regulation of MAP kinase phosphatase levels during larval development of the ascidian Ciona intestinalis.

    PubMed

    Castellano, Immacolata; Ercolesi, Elena; 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.

  8. 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

  9. Chloroplast signaling: retrograde regulation revelations.

    PubMed

    Beale, Samuel I

    2011-05-24

    Developing chloroplasts are able to communicate their status to the nucleus and regulate expression of genes whose products are needed for photosynthesis. Heme is revealed to be a signaling molecule for this retrograde communication.

  10. Chloroplast retrograde signal regulates flowering

    PubMed Central

    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

    2016-01-01

    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

  11. 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

  12. cAMP-pKA signaling regulates multiple steps of fungal infection cooperatively with Cmk1 MAP kinase in Colletotrichum lagenarium.

    PubMed

    Yamauchi, Junko; Takayanagi, Naoyuki; Komeda, Kenichi; Takano, Yoshitaka; Okuno, Tetsuro

    2004-12-01

    In Colletotrichum lagenarium, RPK1 encoding the regulatory subunit of PKA is required for pathogenicity. From the rpkl mutant that forms small colonies, we isolated three growth-suppressor mutants. All rpk1-suppressor mutants are nonpathogenic and contain amino acid changes in the PKA catalytic subunit Cpkl. To assess the roles of cyclic AMP (cAMP) signaling in detail, we generated knockout mutants of CPK1 and the adenylate cyclase gene CAC1. The cpk1 and cac1 mutants are nonpathogenic on cucumber. Interestingly, both of the mutants germinated poorly, suggesting involvement of cAMP signaling in germination. Germination defect in the cpk1 and cac1 mutants is partially rescued by incubation of the conidia at lower concentrations. Germinating conidia of the cpk1 and cac1 mutants can form appressoria, but the appressoria formed by them are nonfunctional, like those of the rpk1 mutant. Cytological analysis indicates that the appressoria of the cpk1 mutant contain larger numbers of lipid bodies compared with the wild type, whereas lipid levels in the rpk1 mutants are lower, suggesting cAMP-mediated regulation of lipid metabolism for appressorium functionality. Furthermore, the cpk1 and cacl mutants have a defect in infectious growth in plant. In C. lagenarium, Cmkl mitogen-activated protein kinase (MAPK) regulates germination, appressorium formation, and infectious growth. These results suggest that cAMP signaling controls multiple steps of fungal infection in cooperative regulation with Cmkl MAPK in C. lagenarium.

  13. 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

  14. BDNF/ TrkB interaction regulates migration of SVZ precursor cells via PI3-K and MAP-K signalling pathways.

    PubMed

    Chiaramello, S; Dalmasso, G; Bezin, L; Marcel, D; Jourdan, F; Peretto, P; Fasolo, A; De Marchis, S

    2007-10-01

    Neuroblasts born in the subventricular zone (SVZ) migrate along the rostral migratory stream, reaching the olfactory bulb (OB) where they differentiate into local interneurons. Several extracellular factors have been suggested to control specific steps of this process. The brain-derived neurotrophic factor (BDNF) has been demonstrated to promote morphological differentiation and survival of OB interneurons. Here we show that BDNF and its receptor TrkB are expressed in vivo throughout the migratory pathway, implying that BDNF might also mediate migratory signals. By using in vitro models we demonstrate that BDNF promotes migration of SVZ neuroblasts, acting both as inducer and attractant through TrkB activation. We show that BDNF induces cAMP response element-binding protein (CREB) activation in migrating neuroblasts via phosphatidylinositol 3-kinase (PI3-K) and mitogen-activated protein kinase (MAP-K) signalling. Pharmacological blockade of these pathways on SVZ explants significantly reduces CREB activation and impairs neuronal migration. This study identifies a function of BDNF in the SVZ system, which involves multiple protein kinase pathways leading to neuroblast migration.

  15. Regulation of CXCR4 Signaling

    PubMed Central

    Busillo, John M.; Benovic, Jeffrey L.

    2007-01-01

    The chemokine receptor CXCR4 belongs to the large superfamily of G protein-coupled receptors, and is directly involved in a number of biological processes including organogenesis, hematopoeisis, and immune response. Recent evidence has highlighted the role of CXCR4 in a variety of diseases including HIV, cancer, and WHIM syndrome. Importantly, the involvement of CXCR4 in cancer metastasis and WHIM syndrome appears to be due to dysregulation of the receptor leading to enhanced signaling. Herein we review what is currently known regarding the regulation of CXCR4 and how dysregulation contributes to disease progression. PMID:17169327

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

    PubMed Central

    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; Shi, Xianglin

    2015-01-01

    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), PGE2 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. PMID:25062774

  17. 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.

  18. 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...

  19. 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

  20. 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…

  1. 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

  2. Regulation of Hedgehog signaling by ubiquitination

    PubMed Central

    Hsia, Elaine Y. C.; Gui, Yirui; Zheng, Xiaoyan

    2015-01-01

    The Hedgehog (Hh) signaling pathway plays crucial roles both in embryonic development and in adult stem cell function. The timing, duration and location of Hh signaling activity need to be tightly controlled. Abnormalities of Hh signal transduction lead to birth defects or malignant tumors. Recent data point to ubiquitination-related posttranslational modifications of several key Hh pathway components as an important mechanism of regulation of the Hh pathway. Here we review how ubiquitination regulates the localization, stability and activity of the key Hh signaling components. PMID:26366162

  3. 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.

  4. Regulation patterns in signaling networks of cancer

    PubMed Central

    2010-01-01

    Background Formation of cellular malignancy results from the disruption of fine tuned signaling homeostasis for proliferation, accompanied by mal-functional signals for differentiation, cell cycle and apoptosis. We wanted to observe central signaling characteristics on a global view of malignant cells which have evolved to selfishness and independence in comparison to their non-malignant counterparts that fulfill well defined tasks in their sample. Results We investigated the regulation of signaling networks with twenty microarray datasets from eleven different tumor types and their corresponding non-malignant tissue samples. Proteins were represented by their coding genes and regulatory distances were defined by correlating the gene-regulation between neighboring proteins in the network (high correlation = small distance). In cancer cells we observed shorter pathways, larger extension of the networks, a lower signaling frequency of central proteins and links and a higher information content of the network. Proteins of high signaling frequency were enriched with cancer mutations. These proteins showed motifs of regulatory integration in normal cells which was disrupted in tumor cells. Conclusion Our global analysis revealed a distinct formation of signaling-regulation in cancer cells when compared to cells of normal samples. From these cancer-specific regulation patterns novel signaling motifs are proposed. PMID:21110851

  5. Plasma membrane regulates Ras signaling networks

    PubMed Central

    Chavan, Tanmay Sanjeev; Muratcioglu, Serena; Marszalek, Richard; Jang, Hyunbum; Keskin, Ozlem; Gursoy, Attila; Nussinov, Ruth; Gaponenko, Vadim

    2015-01-01

    Ras GTPases activate more than 20 signaling pathways, regulating such essential cellular functions as proliferation, survival, and migration. How Ras proteins control their signaling diversity is still a mystery. Several pieces of evidence suggest that the plasma membrane plays a critical role. Among these are: (1) selective recruitment of Ras and its effectors to particular localities allowing access to Ras regulators and effectors; (2) specific membrane-induced conformational changes promoting Ras functional diversity; and (3) oligomerization of membrane-anchored Ras to recruit and activate Raf. Taken together, the membrane does not only attract and retain Ras but also is a key regulator of Ras signaling. This can already be gleaned from the large variability in the sequences of Ras membrane targeting domains, suggesting that localization, environment and orientation are important factors in optimizing the function of Ras isoforms. PMID:27054048

  6. Plasma membrane regulates Ras signaling networks.

    PubMed

    Chavan, Tanmay Sanjeev; Muratcioglu, Serena; Marszalek, Richard; Jang, Hyunbum; Keskin, Ozlem; Gursoy, Attila; Nussinov, Ruth; Gaponenko, Vadim

    2015-01-01

    Ras GTPases activate more than 20 signaling pathways, regulating such essential cellular functions as proliferation, survival, and migration. How Ras proteins control their signaling diversity is still a mystery. Several pieces of evidence suggest that the plasma membrane plays a critical role. Among these are: (1) selective recruitment of Ras and its effectors to particular localities allowing access to Ras regulators and effectors; (2) specific membrane-induced conformational changes promoting Ras functional diversity; and (3) oligomerization of membrane-anchored Ras to recruit and activate Raf. Taken together, the membrane does not only attract and retain Ras but also is a key regulator of Ras signaling. This can already be gleaned from the large variability in the sequences of Ras membrane targeting domains, suggesting that localization, environment and orientation are important factors in optimizing the function of Ras isoforms.

  7. 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.

  8. Regulation of Pseudomonas quinolone signal synthesis in Pseudomonas aeruginosa.

    PubMed

    Wade, Dana S; Calfee, M Worth; Rocha, Edson R; Ling, Elizabeth A; Engstrom, Elana; Coleman, James P; Pesci, Everett C

    2005-07-01

    Pseudomonas aeruginosa is an opportunistic pathogen that causes chronic lung infections in cystic fibrosis patients and is a major source of nosocomial infections. This bacterium controls many virulence factors by using two quorum-sensing systems, las and rhl. The las system is composed of the LasR regulator protein and its cell-to-cell signal, N-(3-oxododecanoyl) homoserine lactone, and the rhl system is composed of RhlR and the signal N-butyryl homoserine lactone. A third intercellular signal, the Pseudomonas quinolone signal (PQS; 2-heptyl-3-hydroxy-4-quinolone), also regulates numerous virulence factors. PQS synthesis requires the expression of multiple operons, one of which is pqsABCDE. Previous experiments showed that the transcription of this operon, and therefore PQS production, is negatively regulated by the rhl quorum-sensing system and positively regulated by the las quorum-sensing system and PqsR (also known as MvfR), a LysR-type transcriptional regulator protein. With the use of DNA mobility shift assays and beta-galactosidase reporter fusions, we have studied the regulation of pqsR and its relationship to pqsA, lasR, and rhlR. We show that PqsR binds the promoter of pqsA and that this binding increases dramatically in the presence of PQS, implying that PQS acts as a coinducer for PqsR. We have also mapped the transcriptional start site for pqsR and found that the transcription of pqsR is positively regulated by lasR and negatively regulated by rhlR. These results suggest that a regulatory chain occurs where pqsR is under the control of LasR and RhlR and where PqsR in turn controls pqsABCDE, which is required for the production of PQS.

  9. Dynamic Redox Regulation of IL-4 Signaling

    PubMed Central

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

    2015-01-01

    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. PMID:26562652

  10. 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

  11. 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.

  12. Mitochondria: master regulators of danger signalling.

    PubMed

    Galluzzi, Lorenzo; Kepp, Oliver; Kroemer, Guido

    2012-12-01

    Throughout more than 1.5 billion years of obligate endosymbiotic co-evolution, mitochondria have developed not only the capacity to control distinct molecular cascades leading to cell death but also the ability to sense (and react to) multiple situations of cellular stress, including viral infection. In addition, mitochondria can emit danger signals that alert the cell or the whole organism of perturbations in homeostasis, hence promoting the induction of cell-intrinsic or systemic adaptive responses, respectively. As such, mitochondria can be considered as master regulators of danger signalling.

  13. Metabolic signals in sleep regulation: recent insights.

    PubMed

    Shukla, Charu; Basheer, Radhika

    2016-01-01

    Sleep and energy balance are essential for health. The two processes act in concert to regulate central and peripheral homeostasis. During sleep, energy is conserved due to suspended activity, movement, and sensory responses, and is redirected to restore and replenish proteins and their assemblies into cellular structures. During wakefulness, various energy-demanding activities lead to hunger. Thus, hunger promotes arousal, and subsequent feeding, followed by satiety that promotes sleep via changes in neuroendocrine or neuropeptide signals. These signals overlap with circuits of sleep-wakefulness, feeding, and energy expenditure. Here, we will briefly review the literature that describes the interplay between the circadian system, sleep-wake, and feeding-fasting cycles that are needed to maintain energy balance and a healthy metabolic profile. In doing so, we describe the neuroendocrine, hormonal/peptide signals that integrate sleep and feeding behavior with energy metabolism.

  14. Metabolic signals in sleep regulation: recent insights

    PubMed Central

    Shukla, Charu; Basheer, Radhika

    2016-01-01

    Sleep and energy balance are essential for health. The two processes act in concert to regulate central and peripheral homeostasis. During sleep, energy is conserved due to suspended activity, movement, and sensory responses, and is redirected to restore and replenish proteins and their assemblies into cellular structures. During wakefulness, various energy-demanding activities lead to hunger. Thus, hunger promotes arousal, and subsequent feeding, followed by satiety that promotes sleep via changes in neuroendocrine or neuropeptide signals. These signals overlap with circuits of sleep-wakefulness, feeding, and energy expenditure. Here, we will briefly review the literature that describes the interplay between the circadian system, sleep-wake, and feeding-fasting cycles that are needed to maintain energy balance and a healthy metabolic profile. In doing so, we describe the neuroendocrine, hormonal/peptide signals that integrate sleep and feeding behavior with energy metabolism. PMID:26793010

  15. 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.

  16. Carrier recovery systems for arbitrarily mapped APK signals

    NASA Astrophysics Data System (ADS)

    Matsuo, Y.; Namiki, J.

    1982-10-01

    This paper introduces new carrier recovery techniques for general amplitude-phase keying (APK) modulation signals. The APK's include not only normal QAM but also arbitrarily mapped APK's, including an unsymmetrical APK. Difficulty in phase error detection due to signal mapping complexity, undesirable stable-lock point existence, and the contradiction between a fast acquisition and an accurate steady state performance can be overcome. For that purpose, an acquisition mode and a steady-state mode are used. Furthermore, read-only memories (ROM) are used for recognizing various system states. Random sampling controlled PLL noise performance and acquisition mode carrier recovery circuit pull-in performance with hysteresis property was obtained.

  17. Reconstruction of Thermographic Signals to Map Perforator Vessels in Humans.

    PubMed

    Liu, Wei-Min; Maivelett, Jordan; Kato, Gregory J; Taylor, James G; Yang, Wen-Chin; Liu, Yun-Chung; Yang, You-Gang; Gorbach, Alexander M

    2012-01-01

    Thermal representations on the surface of a human forearm of underlying perforator vessels have previously been mapped via recovery-enhanced infrared imaging, which is performed as skin blood flow recovers to baseline levels following cooling of the forearm. We noted that the same vessels could also be observed during reactive hyperaemia tests after complete 5-min occlusion of the forearm by an inflatable cuff. However, not all subjects showed vessels with acceptable contrast. Therefore, we applied a thermographic signal reconstruction algorithm to reactive hyperaemia testing, which substantially enhanced signal-to-noise ratios between perforator vessels and their surroundings, thereby enabling their mapping with higher accuracy and a shorter occlusion period.

  18. p38 MAP kinase regulates circadian rhythms in Drosophila.

    PubMed

    Vrailas-Mortimer, Alysia D; Ryan, Sarah M; Avey, Matthew J; Mortimer, Nathan T; Dowse, Harold; Sanyal, Subhabrata

    2014-12-01

    The large repertoire of circadian rhythms in diverse organisms depends on oscillating central clock genes, input pathways for entrainment, and output pathways for controlling rhythmic behaviors. Stress-activated p38 MAP Kinases (p38K), although sparsely investigated in this context, show circadian rhythmicity in mammalian brains and are considered part of the circadian output machinery in Neurospora. We find that Drosophila p38Kb is expressed in clock neurons, and mutants in p38Kb either are arrhythmic or have a longer free-running periodicity, especially as they age. Paradoxically, similar phenotypes are observed through either transgenic inhibition or activation of p38Kb in clock neurons, suggesting a requirement for optimal p38Kb function for normal free-running circadian rhythms. We also find that p38Kb genetically interacts with multiple downstream targets to regulate circadian locomotor rhythms. More specifically, p38Kb interacts with the period gene to regulate period length and the strength of rhythmicity. In addition, we show that p38Kb suppresses the arrhythmic behavior associated with inhibition of a second p38Kb target, the transcription factor Mef2. Finally, we find that manipulating p38K signaling in free-running conditions alters the expression of another downstream target, MNK/Lk6, which has been shown to cycle with the clock and to play a role in regulating circadian rhythms. These data suggest that p38Kb may affect circadian locomotor rhythms through the regulation of multiple downstream pathways.

  19. Signaling in Regulation of Podocyte Phenotypes

    PubMed Central

    Chuang, Peter Y.; He, John C.

    2010-01-01

    The kidney podocyte is a terminally differentiated and highly specialized cell. The function of the glomerular filtration barrier depends on the integrity of the podocyte. Podocyte injury and loss have been observed in human and experimental models of glomerular diseases. Three major podocyte phenotypes have been described in glomerular diseases: effacement, apoptosis, and proliferation. Here, we highlight the signaling cascades that are responsible for the manifestation of these pathologic phenotypes. The integrity of the podocyte foot process is determined by the interaction of nephrin with proteins in the slit diaphragm complex, the regulation of actin dynamics by the Rho family of GTPases, and the transduction of extracellular signals through focal adhesion complexes. Activation of the p38 mitogen-activated protein kinase and transforming growth factor-β 1 causes podocyte apoptosis. Phosphoinositide 3-kinase and its downstream target AKT protect podocytes from apoptosis. In human immunodeficiency virus-associated nephropathy, Src-dependent activation of Stat3, mitogen- activated protein kinase 1,2, and hypoxia-inducible factor 2α is an important driver of podocyte proliferation. At the level of intracellular signaling, it appears that different extracellular signals can converge onto a few pathways to induce changes in the phenotype of podocytes. PMID:19142027

  20. Desmosome regulation and signaling in disease

    PubMed Central

    Broussard, Joshua A.; Getsios, Spiro

    2015-01-01

    Desmosomes are cell-cell adhesive organelles with a well-known role in forming strong intercellular adhesion during embryogenesis and in adult tissues subject to mechanical stress, such as the heart and skin. More recently, desmosome components have also emerged as cell signaling regulators. Loss of expression or interference with the function of desmosome molecules results in diseases of the heart and skin and contributes to cancer progression. However, the underlying molecular mechanisms that result in inherited and acquired disorders remain poorly understood. To address this question, researchers are directing their studies towards determining the functions that occur inside and outside of the junctions and the extent to which functions are adhesion-dependent or independent. This review focuses on recent discoveries that provide insights into the role of desmosomes and desmosome components in cell signaling and disease; wherever possible, we address molecular functions within and outside of the adhesive structure. PMID:25693896

  1. Desmosome regulation and signaling in disease.

    PubMed

    Broussard, Joshua A; Getsios, Spiro; Green, Kathleen J

    2015-06-01

    Desmosomes are cell-cell adhesive organelles with a well-known role in forming strong intercellular adhesion during embryogenesis and in adult tissues subject to mechanical stress, such as the heart and skin. More recently, desmosome components have also emerged as cell signaling regulators. Loss of expression or interference with the function of desmosome molecules results in diseases of the heart and skin and contributes to cancer progression. However, the underlying molecular mechanisms that result in inherited and acquired disorders remain poorly understood. To address this question, researchers are directing their studies towards determining the functions that occur inside and outside of the junctions and the extent to which functions are adhesion-dependent or independent. This review focuses on recent discoveries that provide insights into the role of desmosomes and desmosome components in cell signaling and disease; wherever possible, we address molecular functions within and outside of the adhesive structure.

  2. Promoter nucleosome dynamics regulated by signalling through the CTD code

    PubMed Central

    Materne, Philippe; Anandhakumar, Jayamani; Migeot, Valerie; Soriano, Ignacio; Yague-Sanz, Carlo; Hidalgo, Elena; Mignion, Carole; Quintales, Luis; Antequera, Francisco; Hermand, Damien

    2015-01-01

    The phosphorylation of the RNA polymerase II C-terminal domain (CTD) plays a key role in delineating transcribed regions within chromatin by recruiting histone methylases and deacetylases. Using genome-wide nucleosome mapping, we show that CTD S2 phosphorylation controls nucleosome dynamics in the promoter of a subset of 324 genes, including the regulators of cell differentiation ste11 and metabolic adaptation inv1. Mechanistic studies on these genes indicate that during gene activation a local increase of phospho-S2 CTD nearby the promoter impairs the phospho-S5 CTD-dependent recruitment of Set1 and the subsequent recruitment of specific HDACs, which leads to nucleosome depletion and efficient transcription. The early increase of phospho-S2 results from the phosphorylation of the CTD S2 kinase Lsk1 by MAP kinase in response to cellular signalling. The artificial tethering of the Lsk1 kinase at the ste11 promoter is sufficient to activate transcription. Therefore, signalling through the CTD code regulates promoter nucleosomes dynamics. DOI: http://dx.doi.org/10.7554/eLife.09008.001 PMID:26098123

  3. 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.

  4. p53 Protein-mediated Up-regulation of MAP Kinase Phosphatase 3 (MKP-3) Contributes to the Establishment of the Cellular Senescent Phenotype through Dephosphorylation of Extracellular Signal-regulated Kinase 1/2 (ERK1/2)*

    PubMed Central

    Zhang, Hui; Chi, Yuan; Gao, Kun; Zhang, Xiling; Yao, Jian

    2015-01-01

    Growth arrest is one of the essential features of cellular senescence. At present, the precise mechanisms responsible for the establishment of the senescence-associated arrested phenotype are still incompletely understood. Given that ERK1/2 is one of the major kinases controlling cell growth and proliferation, we examined the possible implication of ERK1/2. Exposure of normal rat epithelial cells to etoposide caused cellular senescence, as manifested by enlarged cell size, a flattened cell body, reduced cell proliferation, enhanced β-galactosidase activity, and elevated p53 and p21. Senescent cells displayed a blunted response to growth factor-induced cell proliferation, which was preceded by impaired ERK1/2 activation. Further analysis revealed that senescent cells expressed a significantly higher level of mitogen-activated protein phosphatase 3 (MKP-3, a cytosolic ERK1/2-targeted phosphatase), which was suppressed by blocking the transcriptional activity of the tumor suppressor p53 with pifithrin-α. Inhibition of MKP-3 activity with a specific inhibitor or siRNA enhanced basal ERK1/2 phosphorylation and promoted cell proliferation. Apart from its role in growth arrest, impairment of ERK1/2 also contributed to the resistance of senescent cells to oxidant-elicited cell injury. These results therefore indicate that p53-mediated up-regulation of MKP-3 contributes to the establishment of the senescent cellular phenotype through dephosphorylating ERK1/2. Impairment of ERK1/2 activation could be an important mechanism by which p53 controls cellular senescence. PMID:25414256

  5. WNK signalling pathways in blood pressure regulation.

    PubMed

    Murthy, Meena; Kurz, Thimo; O'Shaughnessy, Kevin M

    2017-04-01

    Hypertension (high blood pressure) is a major public health problem affecting more than a billion people worldwide with complications, including stroke, heart failure and kidney failure. The regulation of blood pressure is multifactorial reflecting genetic susceptibility, in utero environment and external factors such as obesity and salt intake. In keeping with Arthur Guyton's hypothesis, the kidney plays a key role in blood pressure control and data from clinical studies; physiology and genetics have shown that hypertension is driven a failure of the kidney to excrete excess salt at normal levels of blood pressure. There is a number of rare Mendelian blood pressure syndromes, which have shed light on the molecular mechanisms involved in dysregulated ion transport in the distal kidney. One in particular is Familial hyperkalemic hypertension (FHHt), an autosomal dominant monogenic form of hypertension characterised by high blood pressure, hyperkalemia, hyperchloremic metabolic acidosis, and hypercalciuria. The clinical signs of FHHt are treated by low doses of thiazide diuretic, and it mirrors Gitelman syndrome which features the inverse phenotype of hypotension, hypokalemic metabolic alkalosis, and hypocalciuria. Gitelman syndrome is caused by loss of function mutations in the thiazide-sensitive Na/Cl cotransporter (NCC); however, FHHt patients do not have mutations in the SCL12A3 locus encoding NCC. Instead, mutations have been identified in genes that have revealed a key signalling pathway that regulates NCC and several other key transporters and ion channels in the kidney that are critical for BP regulation. This is the WNK kinase signalling pathway that is the subject of this review.

  6. FGF signalling regulates bone growth through autophagy.

    PubMed

    Cinque, Laura; Forrester, Alison; Bartolomeo, Rosa; Svelto, Maria; Venditti, Rossella; Montefusco, Sandro; Polishchuk, Elena; Nusco, Edoardo; Rossi, Antonio; Medina, Diego L; Polishchuk, Roman; De Matteis, Maria Antonietta; Settembre, Carmine

    2015-12-10

    Skeletal growth relies on both biosynthetic and catabolic processes. While the role of the former is clearly established, how the latter contributes to growth-promoting pathways is less understood. Macroautophagy, hereafter referred to as autophagy, is a catabolic process that plays a fundamental part in tissue homeostasis. We investigated the role of autophagy during bone growth, which is mediated by chondrocyte rate of proliferation, hypertrophic differentiation and extracellular matrix (ECM) deposition in growth plates. Here we show that autophagy is induced in growth-plate chondrocytes during post-natal development and regulates the secretion of type II collagen (Col2), the major component of cartilage ECM. Mice lacking the autophagy related gene 7 (Atg7) in chondrocytes experience endoplasmic reticulum storage of type II procollagen (PC2) and defective formation of the Col2 fibrillary network in the ECM. Surprisingly, post-natal induction of chondrocyte autophagy is mediated by the growth factor FGF18 through FGFR4 and JNK-dependent activation of the autophagy initiation complex VPS34-beclin-1. Autophagy is completely suppressed in growth plates from Fgf18(-/-) embryos, while Fgf18(+/-) heterozygous and Fgfr4(-/-) mice fail to induce autophagy during post-natal development and show decreased Col2 levels in the growth plate. Strikingly, the Fgf18(+/-) and Fgfr4(-/-) phenotypes can be rescued in vivo by pharmacological activation of autophagy, pointing to autophagy as a novel effector of FGF signalling in bone. These data demonstrate that autophagy is a developmentally regulated process necessary for bone growth, and identify FGF signalling as a crucial regulator of autophagy in chondrocytes.

  7. 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

  8. Scube regulates synovial angiogenesis-related signaling.

    PubMed

    Yang, Min; Guo, Mingyang; Hu, Yonghe; Jiang, Yong

    2013-11-01

    Angiogenesis is particularly driven in the synovial microenvironment of Rheumatoid arthritis (RA), and considered as the fundamental cause for the persistent injury and chronic damage. Therefore, exploring the pathomechanism of synovial angiogenesis may provide promising prospects for vascular-targeting treatment of RA. The noval family of Scube proteins is confirmed to overlap significantly in structure characterized by epidermal growth factor (EGF)-like domains and CUB (complement subcomponents C1r/C1s, Uegf, bone morphogenetic protein-1) domain. As secreted glycoprotein and peripheral membrane protein, Scube increases its serum level in response to stimuli of inflammation and hypoxia. In rheumatoid angiogenesis-related signaling system defined by hedgehog (Hh), transforming growth factor (TGF)β and bone morphogenetic protein 2 (BMP2), Scube1 and 2 antagonize BMP2 signaling, suppressing BMP2-induced phospho-Smad1/5/8 level in vivo. Scube3 functions as an endogenous TGFβ receptor ligand, increasing Smad2/3 phosphorylation, and thus upregulates target genes involved in angiogenesis. Via obligate assistance of Scube1 and 3, Scube2 plays a center role to recruit dually lipid-modified Hh transferred from Dispatched A (DispA), increasing Hh secretion by promoting its solubility. These findings support the hypothesis that Scube may regulate synovial angiogenesis may be the ideal vascular targets for anti-rheumatic treatment of RA.

  9. Cytokinin signaling regulates cambial development in poplar.

    PubMed

    Nieminen, Kaisa; Immanen, Juha; Laxell, Marjukka; Kauppinen, Leila; Tarkowski, Petr; Dolezal, Karel; Tähtiharju, Sari; Elo, Annakaisa; Decourteix, Mélanie; Ljung, Karin; Bhalerao, Rishikesh; Keinonen, Kaija; Albert, Victor A; Helariutta, Ykä

    2008-12-16

    Although a substantial proportion of plant biomass originates from the activity of vascular cambium, the molecular basis of radial plant growth is still largely unknown. To address whether cytokinins are required for cambial activity, we studied cytokinin signaling across the cambial zones of 2 tree species, poplar (Populus trichocarpa) and birch (Betula pendula). We observed an expression peak for genes encoding cytokinin receptors in the dividing cambial cells. We reduced cytokinin levels endogenously by engineering transgenic poplar trees (P. tremula x tremuloides) to express a cytokinin catabolic gene, Arabidopsis CYTOKININ OXIDASE 2, under the promoter of a birch CYTOKININ RECEPTOR 1 gene. Transgenic trees showed reduced concentration of a biologically active cytokinin, correlating with impaired cytokinin responsiveness. In these trees, both apical and radial growth was compromised. However, radial growth was more affected, as illustrated by a thinner stem diameter than in WT at same height. To dissect radial from apical growth inhibition, we performed a reciprocal grafting experiment. WT scion outgrew the diameter of transgenic stock, implicating cytokinin activity as a direct determinant of radial growth. The reduced radial growth correlated with a reduced number of cambial cell layers. Moreover, expression of a cytokinin primary response gene was dramatically reduced in the thin-stemmed transgenic trees. Thus, a reduced level of cytokinin signaling is the primary basis for the impaired cambial growth observed. Together, our results show that cytokinins are major hormonal regulators required for cambial development.

  10. 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.

  11. 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

  12. 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

  13. Mapping signaling pathway cross-talk in Drosophila cells

    PubMed Central

    Ammeux, Noemie; Housden, Benjamin E.; Georgiadis, Andrew; Hu, Yanhui; Perrimon, Norbert

    2016-01-01

    During development and homeostasis, cells integrate multiple signals originating either from neighboring cells or systemically. In turn, responding cells can produce signals that act in an autocrine, paracrine, or endocrine manner. Although the nature of the signals and pathways used in cell–cell communication are well characterized, we lack, in most cases, an integrative view of signaling describing the spatial and temporal interactions between pathways (e.g., whether the signals are processed sequentially or concomitantly when two pathways are required for a specific outcome). To address the extent of cross-talk between the major metazoan signaling pathways, we characterized immediate transcriptional responses to either single- or multiple pathway stimulations in homogeneous Drosophila cell lines. Our study, focusing on seven core pathways, epidermal growth factor receptor (EGFR), bone morphogenetic protein (BMP), Jun kinase (JNK), JAK/STAT, Notch, Insulin, and Wnt, revealed that many ligands and receptors are primary targets of signaling pathways, highlighting that transcriptional regulation of genes encoding pathway components is a major level of signaling cross-talk. In addition, we found that ligands and receptors can integrate multiple pathway activities and adjust their transcriptional responses accordingly. PMID:27528688

  14. 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

  15. 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

  16. 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

  17. PAR2 exerts local protection against acute pancreatitis via modulation of MAP kinase and MAP kinase phosphatase signaling.

    PubMed

    Namkung, Wan; Yoon, Jae Seok; Kim, Kyung Hwan; Lee, Min Goo

    2008-11-01

    During acute pancreatitis, protease-activated receptor 2 (PAR2) can be activated by interstitially released trypsin. In the mild form of pancreatitis, PAR2 activation exerts local protection against intrapancreatic damage, whereas, in the severe form of pancreatitis, PAR2 activation mediates some systemic complications. This study aimed to identify the molecular mechanisms of PAR2-mediated protective effects against intrapancreatic damage. A mild form of acute pancreatitis was induced by an intraperitoneal injection of caerulein (40 microg/kg) in rats. Effects of PAR2 activation on intrapancreatic damage and on mitogen-activated protein (MAP) kinase signaling were assessed. Caerulein treatment activated extracellular signal-regulated kinase (ERK) and c-Jun NH(2)-terminal kinase (JNK) within 15 min and maintained phosphorylation of ERK and JNK for 2 h in the rat pancreas. Although PAR2 activation by the pretreatment with PAR2-activating peptide (AP) itself increased ERK phosphorylation in rat pancreas, the same treatment remarkably decreased caerulein-induced activation of ERK and JNK principally by accelerating their dephosphorylation. Inhibition of ERK and JNK phosphorylation by the pretreatment with MAP/ERK kinase (MEK) or JNK inhibitors decreased caerulein-induced pancreatic damage that was similar to the effect induced by PAR2-AP. Notably, in caerulein-treated rats, PAR2-AP cotreatment highly increased the expression of a group of MAP kinase phosphatases (MKPs) that deactivate ERK and JNK. The above results imply that downregulation of MAP kinase signaling by MKP induction is a key mechanism involved in the protective effects of PAR2 activation on caerulein-induced intrapancreatic damage.

  18. Regulation of EB1/3 proteins by classical MAPs in neurons

    PubMed Central

    Sayas, CL; Avila, Jesús

    2014-01-01

    Microtubules (MTs) are key cytoskeletal elements in developing and mature neurons. MT reorganization underlies the morphological changes that occur during neuronal development. Furthermore, MTs contribute to the maintenance of neuronal architecture, enable intracellular transport and act as scaffolds for signaling molecules. Thus, a fine-tuned regulation of MT dynamics and stability is crucial for the correct differentiation and functioning of neurons. Different types of proteins contribute to the regulation of the MT state, such as plus-end tracking proteins (+TIPs), which interact with the plus-ends of growing microtubules, and classical microtubule-associated proteins (MAPs), which bind along the microtubule lattice. Recent evidence indicates that MAPs interplay with End Binding Proteins (EBs), the core +TIPs, in neuronal cells. This might contribute to the orchestrated regulation of MT dynamics in neurons. In this mini-review article, we address recent research on the neuronal crosstalk between EBs and classical MAPs and speculate on its possible functional relevance. PMID:24452057

  19. A developmentally regulated MAP kinase activated by hydration in tobacco pollen.

    PubMed Central

    Wilson, C; Voronin, V; Touraev, A; Vicente, O; Heberle-Bors, E

    1997-01-01

    A novel mitogen-activated protein (MAP) kinase signaling pathway has been identified in tobacco. This pathway is developmentally regulated during pollen maturation and is activated by hydration during pollen germination. Analysis of different stages of pollen development showed that transcriptional and translational induction of MAP kinase synthesis occurs at the mid-bicellular stage of pollen maturation. However, the MAP kinase is stored in an inactive form in the mature, dry pollen grain. Kinase activation is very rapid after hydration of the dry pollen, peaking at approximately 5 min and decreasing thereafter. Immunoprecipitation of the kinase activity by an anti-phosphotyrosine antibody is consistent with the activation of a MAP kinase. The kinetics of activation suggest that the MAP kinase plays a role in the activation of the pollen grain after hydration rather than in pollen tube growth. PMID:9401129

  20. 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.

  1. 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.

  2. Brown adipocyte differentiation is regulated by hedgehog signaling during development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During development, brown fat tissue arises from mesenchymal precursor cells under the control of signaling networks that are not yet well understood. The Hedgehog (Hh) signaling pathway is one of the major signaling pathways that regulate mesenchymal cell fate. However, whether the Hh pathway contr...

  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. Scaffolds are 'active' regulators of signaling modules.

    PubMed

    Alexa, Anita; Varga, János; Reményi, Attila

    2010-11-01

    Signaling cascades, in addition to proteins with obvious signaling-relevant activities (e.g. protein kinases or receptors), also employ dedicated 'inactive' proteins whose functions appear to be the organization of the former components into higher order complexes through protein-protein interactions. The core function of signaling adaptors, anchors and scaffolds is the recruitment of proteins into one macromolecular complex. Several recent studies have demonstrated that the recruiter and the recruited molecules mutually influence each other in a scaffolded complex. This yields fundamentally novel properties for the signaling complex as a whole. Because these are not merely additive to the properties of the individual components, scaffolded signaling complexes may behave as functionally distinct modules.

  5. 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

  6. Regulation of neurogenesis by calcium signaling

    PubMed Central

    Toth, Anna B.; Shum, Andrew K.; Prakriya, Murali

    2017-01-01

    Calcium (Ca2+) signaling has essential roles in the development of the nervous system from neural induction to the proliferation, migration, and differentiation of neural cells. Ca2+ signaling pathways are shaped by interactions among metabotropic signaling cascades, intracellular Ca2+ stores, ion channels, and a multitude of downstream effector proteins that activate specific genetic programs. The temporal and spatial dynamics of Ca2+ signals are widely presumed to control the highly diverse yet specific genetic programs that establish the complex structures of the adult nervous system. Progress in the last two decades has led to significant advances in our understanding of the functional architecture of Ca2+ signaling networks involved in neurogenesis. In this review, we assess the literature on the molecular and functional organization of Ca2+ signaling networks in the developing nervous system and its impact on neural induction, gene expression, proliferation, migration, and differentiation. Particular emphasis is placed on the growing evidence for the involvement of store-operated Ca2+ release-activated Ca2+ (CRAC) channels in these processes. PMID:27020657

  7. The role of proteases in regulating Eph/ephrin signaling

    PubMed Central

    Atapattu, Lakmali; Lackmann, Martin; Janes, Peter W

    2014-01-01

    Proteases regulate a myriad of cell functions, both in normal and disease states. In addition to protein turnover, they regulate a range of signaling processes, including those mediated by Eph receptors and their ephrin ligands. A variety of proteases is reported to directly cleave Ephs and/or ephrins under different conditions, to promote receptor and/or ligand shedding, and regulate receptor/ligand internalisation and signaling. They also cleave other adhesion proteins in response to Eph-ephrin interactions, to indirectly facilitate Eph-mediated functions. Proteases thus contribute to Eph/ephrin mediated changes in cell-cell and cell-matrix interactions, in cell morphology and in cell migration and invasion, in a manner which appears to be tightly regulated by, and co-ordinated with, Eph signaling. This review summarizes the current literature describing the function and regulation of protease activities during Eph/ephrin-mediated cell signaling. PMID:25482632

  8. The dynamic mechanism of noisy signal decoding in gene regulation

    PubMed Central

    Liu, Peijiang; Wang, Haohua; Huang, Lifang; Zhou, Tianshou

    2017-01-01

    Experimental evidence supports that signaling pathways can induce different dynamics of transcription factor (TF) activation, but how an input signal is encoded by such a dynamic, noisy TF and further decoded by downstream genes remains largely unclear. Here, using a system of stochastic transcription with signal regulation, we show that (1) keeping the intensity of the signal noise invariant but prolonging the signal duration can both enhance the mutual information (MI) and reduce the energetic cost (EC); (2) if the signal duration is fixed, the larger MI needs the larger EC, but if the signal period is fixed, there is an optimal time that the signal spends at one lower branch, such that MI reaches the maximum; (3) if both the period and the duration are simultaneously fixed, increasing the input noise can always enhance MI in the case of transcription regulation rather than in the case of degradation regulation. In addition, we find that the input noise can induce stochastic focusing in a regulation-dependent manner. These results reveal not only the dynamic mechanism of noisy signal decoding in gene regulation but also the essential role of external noise in controlling gene expression levels. PMID:28176840

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

    PubMed

    Davière, Jean-Michel; Achard, Patrick

    2016-01-04

    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.

  10. 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.

  11. Erbin regulates NRG1 signaling and myelination

    PubMed Central

    Tao, Yanmei; Dai, Penggao; Liu, Yu; Marchetto, Sylvie; Xiong, Wen-Cheng; Borg, Jean-Paul; Mei, Lin

    2009-01-01

    Neuregulin 1 (NRG1) plays a critical role in myelination. However, little is known about regulatory mechanisms of NRG1 signaling. We show here that Erbin, a protein that contains leucine-rich repeats (LRR) and a PSD95-Dlg-Zol (PDZ) domain and that interacts specifically with ErbB2, is necessary for NRG1 signaling and myelination of peripheral nervous system (PNS). In Erbin null mice, myelinated axons were hypomyelinated with reduced expression of P0, a marker of mature myelinating Schwann cells (SCs), whereas unmyelinated axons were aberrantly ensheathed in Remak bundles, with increased numbers of axons in the bundles and in pockets. The morphological deficits were associated with decreased nerve conduction velocity and increased sensory threshold to mechanistic stimulation. These phenotypes were duplicated in erbinΔC/ΔC mice, in which Erbin lost the PDZ domain to interact with ErbB2. Moreover, ErbB2 was reduced at protein levels in both Erbin mutant sciatic nerves, and ErbB2 became unstable and NRG1 signaling compromised when Erbin expression was suppressed. These observations indicate a critical role of Erbin in myelination and identify a regulatory mechanism of NRG1 signaling. Our results suggest that Erbin, via the PDZ domain, binds to and stabilizes ErbB2, which is necessary for NRG1 signaling that has been implicated in tumorigenesis, heart development, and neural function. PMID:19458253

  12. Oncogenic KRAS Regulates Tumor Cell Signaling via Stromal Reciprocation

    PubMed Central

    Tape, Christopher J.; Ling, Stephanie; Dimitriadi, Maria; McMahon, Kelly M.; Worboys, Jonathan D.; Leong, Hui Sun; Norrie, Ida C.; Miller, Crispin J.; Poulogiannis, George; Lauffenburger, Douglas A.; Jørgensen, Claus

    2016-01-01

    Summary Oncogenic mutations regulate signaling within both tumor cells and adjacent stromal cells. Here, we show that oncogenic KRAS (KRASG12D) also regulates tumor cell signaling via stromal cells. By combining cell-specific proteome labeling with multivariate phosphoproteomics, we analyzed heterocellular KRASG12D signaling in pancreatic ductal adenocarcinoma (PDA) cells. Tumor cell KRASG12D engages heterotypic fibroblasts, which subsequently instigate reciprocal signaling in the tumor cells. Reciprocal signaling employs additional kinases and doubles the number of regulated signaling nodes from cell-autonomous KRASG12D. Consequently, reciprocal KRASG12D produces a tumor cell phosphoproteome and total proteome that is distinct from cell-autonomous KRASG12D alone. Reciprocal signaling regulates tumor cell proliferation and apoptosis and increases mitochondrial capacity via an IGF1R/AXL-AKT axis. These results demonstrate that oncogene signaling should be viewed as a heterocellular process and that our existing cell-autonomous perspective underrepresents the extent of oncogene signaling in cancer. Video Abstract PMID:27087446

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

    PubMed Central

    Gerber, Kyle J.; Squires, Katherine E.

    2016-01-01

    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. PMID:26655302

  14. BAR domain proteins regulate Rho GTPase signaling

    PubMed Central

    Aspenström, Pontus

    2014-01-01

    BAR proteins comprise a heterogeneous group of multi-domain proteins with diverse biological functions. The common denominator is the Bin-Amphiphysin-Rvs (BAR) domain that not only confers targeting to lipid bilayers, but also provides scaffolding to mold lipid membranes into concave or convex surfaces. This function of BAR proteins is an important determinant in the dynamic reconstruction of membrane vesicles, as well as of the plasma membrane. Several BAR proteins function as linkers between cytoskeletal regulation and membrane dynamics. These links are provided by direct interactions between BAR proteins and actin-nucleation-promoting factors of the Wiskott-Aldrich syndrome protein family and the Diaphanous-related formins. The Rho GTPases are key factors for orchestration of this intricate interplay. This review describes how BAR proteins regulate the activity of Rho GTPases, as well as how Rho GTPases regulate the function of BAR proteins. This mutual collaboration is a central factor in the regulation of vital cellular processes, such as cell migration, cytokinesis, intracellular transport, endocytosis, and exocytosis. PMID:25483303

  15. Ubiquitin-Dependent Regulation of TGFβ Signaling in Cancer1

    PubMed Central

    Izzi, Luisa; Attisano, Liliana

    2006-01-01

    Abstract The transforming growth factorβ (TGFβ) superfamily regulates a broad spectrum of biological responses throughout embryonic development and adult life, including cell proliferation and differentiation, epithelial-to-mesenchymal transition, apoptosis, and angiogenesis. TGFβ members initiate signaling by bringing together a complex of serine/threonine kinase receptors that transmit signals through intracellular Smad proteins. Genetic alterations in numerous components of the TGFβ signaling pathway have been associated with several human cancers. In addition, tight regulation of TGFβ signaling is pivotal to the maintenance of homeostasis and the prevention of carcinogenesis. The ubiquitin/proteosome system is one mechanism by which cells regulate the expression and activity of effectors of the TGFβ signaling cascade. Mounting evidence also suggests that disruption of the ubiquitin-dependent degradation of components of the TGFβ pathway leads to the development and progression of cancer. Therefore, understanding how these two pathways intertwine will contribute to the advancement of our knowledge of cancer development. PMID:16925950

  16. 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

  17. Signaling pathways involved in MDSC regulation.

    PubMed

    Trikha, Prashant; Carson, William E

    2014-08-01

    The immune system has evolved mechanisms to protect the host from the deleterious effects of inflammation. The generation of immune suppressive cells like myeloid derived suppressor cells (MDSCs) that can counteract T cell responses represents one such strategy. There is an accumulation of immature myeloid cells or MDSCs in bone marrow (BM) and lymphoid organs under pathological conditions such as cancer. MDSCs represent a population of heterogeneous myeloid cells comprising of macrophages, granulocytes and dendritic cells that are at early stages of development. Although, the precise signaling pathways and molecular mechanisms that lead to MDSC generation and expansion in cancer remains to be elucidated. It is widely believed that perturbation of signaling pathways involved during normal hematopoietic and myeloid development under pathological conditions such as tumorogenesis contributes to the development of suppressive myeloid cells. In this review we discuss the role played by key signaling pathways such as PI3K, Ras, Jak/Stat and TGFb during myeloid development and how their deregulation under pathological conditions can lead to the generation of suppressive myeloid cells or MDSCs. Targeting these pathways should help in elucidating mechanisms that lead to the expansion of MDSCs in cancer and point to methods for eliminating these cells from the tumor microenvironment.

  18. 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

  19. 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

  20. Dynein-mediated trafficking negatively regulates LET-23 EGFR signaling

    PubMed Central

    Skorobogata, Olga; Meng, Jassy; Gauthier, Kimberley; Rocheleau, Christian E.

    2016-01-01

    Epidermal growth factor receptor (EGFR) signaling is essential for animal development, and increased signaling underlies many human cancers. Identifying the genes and cellular processes that regulate EGFR signaling in vivo will help to elucidate how this pathway can become inappropriately activated. Caenorhabditis elegans vulva development provides an in vivo model to genetically dissect EGFR signaling. Here we identified a mutation in dhc-1, the heavy chain of the cytoplasmic dynein minus end–directed microtubule motor, in a genetic screen for regulators of EGFR signaling. Despite the many cellular functions of dynein, DHC-1 is a strong negative regulator of EGFR signaling during vulva induction. DHC-1 is required in the signal-receiving cell and genetically functions upstream or in parallel to LET-23 EGFR. LET-23 EGFR accumulates in cytoplasmic foci in dhc-1 mutants, consistent with mammalian cell studies in which dynein is shown to regulate late endosome trafficking of EGFR with the Rab7 GTPase. However, we found different distributions of LET-23 EGFR foci in rab-7 versus dhc-1 mutants, suggesting that dynein functions at an earlier step of LET-23 EGFR trafficking to the lysosome than RAB-7. Our results demonstrate an in vivo role for dynein in limiting LET-23 EGFR signaling via endosomal trafficking. PMID:27654944

  1. 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

  2. Interspecific Nematode Signals Regulate Dispersal Behavior

    PubMed Central

    Kaplan, Fatma; Alborn, Hans T.; von Reuss, Stephan H.; Ajredini, Ramadan; Ali, Jared G.; Akyazi, Faruk; Stelinski, Lukasz L.; Edison, Arthur S.; Schroeder, Frank C.; Teal, Peter E.

    2012-01-01

    Background Dispersal is an important nematode behavior. Upon crowding or food depletion, the free living bacteriovorus nematode Caenorhabditis elegans produces stress resistant dispersal larvae, called dauer, which are analogous to second stage juveniles (J2) of plant parasitic Meloidogyne spp. and infective juveniles (IJ)s of entomopathogenic nematodes (EPN), e.g., Steinernema feltiae. Regulation of dispersal behavior has not been thoroughly investigated for C. elegans or any other nematode species. Based on the fact that ascarosides regulate entry in dauer stage as well as multiple behaviors in C. elegans adults including mating, avoidance and aggregation, we hypothesized that ascarosides might also be involved in regulation of dispersal behavior in C. elegans and for other nematodes such as IJ of phylogenetically related EPNs. Methodology/Principal Findings Liquid chromatography-mass spectrometry analysis of C. elegans dauer conditioned media, which shows strong dispersing activity, revealed four known ascarosides (ascr#2, ascr#3, ascr#8, icas#9). A synthetic blend of these ascarosides at physiologically relevant concentrations dispersed C. elegans dauer in the presence of food and also caused dispersion of IJs of S. feltiae and J2s of plant parasitic Meloidogyne spp. Assay guided fractionation revealed structural analogs as major active components of the S. feltiae (ascr#9) and C. elegans (ascr#2) dispersal blends. Further analysis revealed ascr#9 in all Steinernema spp. and Heterorhabditis spp. infected insect host cadavers. Conclusions/Significance Ascaroside blends represent evolutionarily conserved, fundamentally important communication systems for nematodes from diverse habitats, and thus may provide sustainable means for control of parasitic nematodes. PMID:22701701

  3. 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.

  4. 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

  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. The Growth Hormone Secretagogue Receptor: Its Intracellular Signaling and Regulation

    PubMed Central

    Yin, Yue; Li, Yin; Zhang, Weizhen

    2014-01-01

    The growth hormone secretagogue receptor (GHSR), also known as the ghrelin receptor, is involved in mediating a wide variety of biological effects of ghrelin, including: stimulation of growth hormone release, increase of food intake and body weight, modulation of glucose and lipid metabolism, regulation of gastrointestinal motility and secretion, protection of neuronal and cardiovascular cells, and regulation of immune function. Dependent on the tissues and cells, activation of GHSR may trigger a diversity of signaling mechanisms and subsequent distinct physiological responses. Distinct regulation of GHSR occurs at levels of transcription, receptor interaction and internalization. Here we review the current understanding on the intracellular signaling pathways of GHSR and its modulation. An overview of the molecular structure of GHSR is presented first, followed by the discussion on its signaling mechanisms. Finally, potential mechanisms regulating GHSR are reviewed. PMID:24651458

  7. Integration of Brassinosteroid Signal Transduction with the Transcription Network for Plant Growth Regulation in Arabidopsis

    PubMed Central

    Sun, Yu; Fan, Xi-Ying; Cao, Dong-Mei; He, Kun; Tang, Wenqiang; Zhu, Jia-Ying; He, Jun-Xian; Bai, Ming-Yi; Zhu, Shengwei; Oh, Eunkyoo; Patil, Sunita; Kim, Tae-Wuk; Ji, Hongkai; Wong, Wing Hong; Rhee, Seung Y.; Wang, Zhi-Yong

    2010-01-01

    SUMMARY Brassinosteroids (BRs) regulate a wide range of developmental and physiological processes in plants through a receptor-kinase signaling pathway that controls the BZR transcription factors. Here we use transcript profiling and chromatin-immunoprecipitation microarray (ChIP-chip) experiments to identify 953 BR-regulated BZR1 target (BRBT) genes. Functional studies of selected BRBTs further demonstrate roles in BR-promotion of cell elongation. The BRBT genes reveal numerous molecular links between the BR signaling pathway and downstream components involved in developmental and physiological processes. Furthermore, the results reveal extensive crosstalk between BR and other hormonal and light signaling pathways at multiple levels. For example, BZR1 not only controls the expression of many signaling components of other hormonal and light pathways, but also co-regulates common target genes with light-signaling transcription factors. Our results provide a genomic map of steroid hormone actions in plants, which reveals a regulatory network that integrates hormonal and light signaling pathways for plant growth regulation. PMID:21074725

  8. Drosophila Vps36 regulates Smo trafficking in Hedgehog signaling.

    PubMed

    Yang, Xiaofeng; Mao, Feifei; Lv, Xiangdong; Zhang, Zhao; Fu, Lin; Lu, Yi; Wu, Wenqing; Zhou, Zhaocai; Zhang, Lei; Zhao, Yun

    2013-09-15

    The hedgehog (Hh) signaling pathway plays a very important role in metazoan development by controlling pattern formation. Malfunction of the Hh signaling pathway leads to numerous serious human diseases, including congenital disorders and cancers. The seven-transmembrane domain protein Smoothened (Smo) is a key transducer of the Hh signaling pathway, and mediates the graded Hh signal across the cell plasma membrane, thereby inducing the proper expression of downstream genes. Smo accumulation on the cell plasma membrane is regulated by its C-tail phosphorylation and the graded Hh signal. The inhibitory mechanism for Smo membrane accumulation in the absence of Hh, however, is still largely unknown. Here, we report that Vps36 of the ESCRT-II complex regulates Smo trafficking between the cytosol and plasma membrane by specifically recognizing the ubiquitin signal on Smo in the absence of Hh. Furthermore, in the absence of Hh, Smo is ubiquitylated on its cytoplasmic part, including its internal loops and C-tail. Taken together, our data suggest that the ESCRT-II complex, especially Vps36, has a special role in controlling Hh signaling by targeting the membrane protein Smo for its trafficking in the absence of Hh, thereby regulating Hh signaling activity.

  9. 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.

  10. 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.

  11. 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.

  12. Regulation of cardiomyocyte signaling by RGS proteins: differential selectivity towards G proteins and susceptibility to regulation.

    PubMed

    Hao, Jianming; Michalek, Christina; Zhang, Wei; Zhu, Ming; Xu, Xiaomei; Mende, Ulrike

    2006-07-01

    Many signals that regulate cardiomyocyte growth, differentiation and function are mediated via heterotrimeric G proteins, which are under the control of RGS proteins (Regulators of G protein Signaling). Several RGS proteins are expressed in the heart, but so far little is known about their function and regulation. Using adenoviral gene transfer, we conducted the first comprehensive analysis of the capacity and selectivity of the major cardiac RGS proteins (RGS2-RGS5) to regulate central G protein-mediated signaling pathways in adult ventricular myocytes (AVM). All four RGS proteins potently inhibited Gq/11-mediated phospholipase C beta stimulation and cell growth (assessed in neonatal myocytes). Importantly, RGS2 selectively inhibited Gq/11 signaling, whereas RGS3, RGS4 and RGS5 had the capacity to regulate both Gq/11 and Gi/o signaling (carbachol-induced cAMP inhibition). Gs signaling was unaffected, and, contrary to reports in other cell lines, RGS2-RGS5 did not appear to regulate adenylate cyclase directly in AVM. Since RGS proteins can be highly regulated in their expression by many different stimuli, we also tested the hypothesis that RGS expression is subject to G protein-mediated regulation in AVM and determined the specificity with which enhanced G protein signaling alters endogenous RGS expression in AVM. RGS2 mRNA and protein were markedly but transiently up-regulated by enhanced Gq/11 signaling (alpha1-adrenergic stimulation or Galphaq* overexpression), possibly by a negative feedback mechanism. In contrast, the other negative regulators of Gq/11 signaling (RGS3-RGS5) were unchanged. Endogenous RGS2 (but not RGS3-RGS5) expression was also up-regulated in cells with enhanced AC signaling (beta-adrenergic or forskolin stimulation). Taken together, these findings suggest diverse roles of RGS proteins in regulating myocyte signaling. RGS2 emerged as the only selective and highly regulated inhibitor of Gq/11 signaling that could potentially become a promising

  13. EP2 Receptor Signaling Regulates Microglia Death

    PubMed Central

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

    2015-01-01

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

  14. PB1 Domain-Dependent Signaling Complex Is Required for Extracellular Signal-Regulated Kinase 5 Activation

    PubMed Central

    Nakamura, Kazuhiro; Uhlik, Mark T.; Johnson, Nancy L.; Hahn, Klaus M.; Johnson, Gary L.

    2006-01-01

    MEKK2, MEK5, and extracellular signal-regulated kinase 5 (ERK5) are members of a three-kinase cascade for the activation of ERK5. MEK5 is the only MAP2K to express a PB1 domain, and we have shown that it heterodimerizes with the PB1 domain of MEKK2. Here we demonstrate the MEK5 PB1 domain is a scaffold that also binds ERK5, functionally forming a MEKK2-MEK5-ERK5 complex. Reconstitution assays and CFP/YFP imaging (fluorescence resonance energy transfer [FRET]) measuring YFP-MEKK2/CFP-MEK5 and CFP-MEK5/YFP-ERK5 interactions define distinct MEK5 PB1 domain binding sites for MEKK2 and ERK5, with a C-terminal extension of the PB1 domain contributing to ERK5 binding. Stimulus-dependent CFP/YFP FRET in combination with mutational analysis was used to define MEK5 PB1 domain residues critical for the interaction of MEKK2/MEK5 and MEK5/ERK5 required for activation of the ERK5 pathway in living cells. Fusion of the MEK5 PB1 domain to the N terminus of MEK1 confers ERK5 regulation by a MAP2K normally regulating only ERK1/2. The MEK5 PB1 domain confers stringent MAP3K regulation of ERK5 relative to more promiscuous MAP3K control of ERK1/2, JNK, and p38. PMID:16507987

  15. Ethylene signaling and regulation in plant growth and stress responses.

    PubMed

    Wang, Feifei; Cui, Xiankui; Sun, Yue; Dong, Chun-Hai

    2013-07-01

    Gaseous phytohormone ethylene affects many aspects of plant growth and development. The ethylene signaling pathway starts when ethylene binds to its receptors. Since the cloning of the first ethylene receptor ETR1 from Arabidopsis, a large number of studies have steadily improved our understanding of the receptors and downstream components in ethylene signal transduction pathway. This article reviews the regulation of ethylene receptors, signal transduction, and the posttranscriptional modulation of downstream components. Functional roles and importance of the ethylene signaling components in plant growth and stress responses are also discussed. Cross-reactions of ethylene with auxin and other phytohormones in plant organ growth will be analyzed. The studies of ethylene signaling in plant growth, development, and stress responses in the past decade greatly advanced our knowledge of how plants respond to endogenous signals and environmental factors.

  16. Transcriptional regulation of mouse hypoglossal motor neuron somatotopic map formation.

    PubMed

    Chen, Xin; Wang, Jae Woong; Salin-Cantegrel, Adele; Dali, Rola; Stifani, Stefano

    2016-11-01

    Somatic motor neurons in the hypoglossal nucleus innervate tongue muscles controlling vital functions such as chewing, swallowing and respiration. Formation of functional hypoglossal nerve circuits depends on the establishment of precise hypoglossal motor neuron maps correlating with specific tongue muscle innervations. Little is known about the molecular mechanisms controlling mammalian hypoglossal motor neuron topographic map formation. Here we show that combinatorial expression of transcription factors Runx1, SCIP and FoxP1 defines separate mouse hypoglossal motor neuron groups with different topological, neurotransmitter and calcium-buffering phenotypes. Runx1 and SCIP are coexpressed in ventromedial hypoglossal motor neurons involved in control of tongue protrusion whereas FoxP1 is expressed in dorsomedial motor neurons associated with tongue retraction. Establishment of separate hypoglossal motor neuron maps depends in part on Runx1-mediated suppression of ventrolateral and dorsomedial motor neuron phenotypes and regulation of FoxP1 expression pattern. These findings suggest that combinatorial actions of Runx1, SCIP and FoxP1 are important for mouse hypoglossal nucleus somatotopic map formation.

  17. Elucidating the regulation of complex signalling systems in plant cells.

    PubMed

    Liu, Junli; Lindsey, Keith; Hussey, Patrick J

    2014-02-01

    The pollen tube represents a model system for the study of tip growth, and the root provides a valuable system to study gene and signalling networks in plants. In the present article, using the two systems as examples, we discuss how to elucidate the regulation of complex signalling systems in plant cells. First, we discuss how hormones and related genes in plant root development form a complex interacting network, and their activities are interdependent. Therefore their roles in root development must be analysed as an integrated system, and elucidation of the regulation of each component requires the adaptation of a novel modelling methodology: regulation analysis. Secondly, hydrodynamics, cell wall and ion dynamics are all important properties that regulate plant cell growth. We discuss how regulation analysis can be applied to study the regulation of hydrodynamics, cell wall and ion dynamics, using pollen tube growth as a model system. Finally, we discuss future prospects for elucidating the regulation of complex signalling systems in plant cells.

  18. 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

  19. Metabolism strikes back: metabolic flux regulates cell signaling

    PubMed Central

    Metallo, Christian M.; Vander Heiden, Matthew G.

    2010-01-01

    Mammalian cells depend on growth factor signaling to take up nutrients; however, coordination of glucose and glutamine uptake has been a mystery. In this issue of Genes & Development, Wellen and colleagues (pp. 2784–2799) show that glucose flux through the hexosamine biosynthesis pathway regulates growth factor receptor glycosylation and enables glutamine consumption. This mechanism ensures that cells do not engage in anabolic metabolism when nutrients are limiting, and highlights how substrate availability for protein modifications can modulate cell signaling. PMID:21159812

  20. A chloroplast retrograde signal regulates nuclear alternative splicing

    PubMed Central

    Petrillo, Ezequiel; Herz, Micaela A. Godoy; Fuchs, Armin; Reifer, Dominik; Fuller, John; Yanovsky, Marcelo J.; Simpson, Craig; Brown, John W. S.; Barta, Andrea; Kalyna, Maria; Kornblihtt, Alberto R.

    2015-01-01

    Light is a source of energy and also a regulator of plant physiological adaptations. We show here that light/dark conditions affect alternative splicing of a subset of Arabidopsis genes preferentially encoding proteins involved in RNA processing. The effect requires functional chloroplasts and is also observed in roots when the communication with the photosynthetic tissues is not interrupted, suggesting that a signaling molecule travels through the plant. Using photosynthetic electron transfer inhibitors with different mechanisms of action we deduce that the reduced pool of plastoquinones initiates a chloroplast retrograde signaling that regulates nuclear alternative splicing and is necessary for proper plant responses to varying light conditions. PMID:24763593

  1. Signaling Mechanisms Regulating Myelination in the Central Nervous System

    PubMed Central

    AHRENDSEN, Jared T.; MACKLIN, Wendy B.

    2014-01-01

    The precise and coordinated production of myelin is essential for proper development and function of the nervous system. Diseases that disrupt myelin, including multiple sclerosis (MS), cause significant functional disability. Current treatment aims to reduce the inflammatory component of the disease, thereby preventing damage resulting from demyelination. However, therapies are not yet available to improve natural repair processes after damage has already occurred. A thorough understanding of the signaling mechanisms that regulate myelin generation will improve our ability to enhance repair. In this review, we summarize the positive and negative regulators of myelination, focusing primarily on central nervous system myelination. Axon-derived signals, extracellular signals from both diffusible factors and the extracellular matrix, and intracellular signaling pathways within myelinating oligodendrocytes are discussed. Much more is known about the positive regulators that drive myelination, while less is known about the negative regulators that shift active myelination to myelin maintenance at the appropriate time. Therefore, we also provide new data on potential negative regulators of CNS myelination. PMID:23558589

  2. 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.

  3. FGF signaling specifies hematopoietic stem cells through its regulation of somitic Notch signaling

    PubMed Central

    Lee, Yoonsung; Manegold, Jennifer E; Kim, Albert D; Pouget, Claire; Stachura, David L; Clements, Wilson K; Traver, David

    2014-01-01

    Hematopoietic stem cells (HSCs) derive from hemogenic endothelial cells of the primitive dorsal aorta (DA) during vertebrate embryogenesis. The molecular mechanisms governing this unique endothelial to hematopoietic transition remain unclear. Here, we demonstrate a novel requirement for fibroblast growth factor (FGF) signaling in HSC emergence. This requirement is non-cell-autonomous, and acts within the somite to bridge the Wnt and Notch signaling pathways. We previously demonstrated that Wnt16 regulates the somitic expression of two Notch ligands, deltaC (dlc) and deltaD (dld), whose combined function is required for HSC fate. How Wnt16 connects to Notch function has remained an open question. Our current studies demonstrate that FGF signaling, via FGF receptor 4 (Fgfr4), mediates a signal transduction pathway between Wnt16 and Dlc, but not Dld, to regulate HSC specification. Our findings demonstrate that FGF signaling acts as a key molecular relay within the developmental HSC niche to instruct HSC fate. PMID:25428693

  4. PSM/SH2-B distributes selected mitogenic receptor signals to distinct components in the PI3-kinase and MAP kinase signaling pathways.

    PubMed

    Deng, Youping; Xu, Hu; Riedel, Heimo

    2007-02-15

    The Pro-rich, PH, and SH2 domain containing mitogenic signaling adapter PSM/SH2-B has been implicated as a cellular partner of various mitogenic receptor tyrosine kinases and related signaling mechanisms. Here, we report in a direct comparison of three peptide hormones, that PSM participates in the assembly of distinct mitogenic signaling complexes in response to insulin or IGF-I when compared to PDGF in cultured normal fibroblasts. The complex formed in response to insulin or IGF-I involves the respective peptide hormone receptor and presumably the established components leading to MAP kinase activation. However, our data suggest an alternative link from the PDGF receptor via PSM directly to MEK1/2 and consequently also to p44/42 activation, possibly through a scaffold protein. At least two PSM domains participate, the SH2 domain anticipated to link PSM to the respective receptor and the Pro-rich region in an association with an unidentified downstream component resulting in direct MEK1/2 and p44/42 regulation. The PDGF receptor signaling complex formed in response to PDGF involves PI 3-kinase in addition to the same components and interactions as described for insulin or IGF-I. PSM associates with PI 3-kinase via p85 and in addition the PSM PH domain participates in the regulation of PI 3-kinase activity, presumably through membrane interaction. In contrast, the PSM Pro-rich region appears to participate only in the MAP kinase signal. Both pathways contribute to the mitogenic response as shown by cell proliferation, survival, and focus formation. PSM regulates p38 MAP kinase activity in a pathway unrelated to the mitogenic response.

  5. 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.

  6. 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.

  7. Interferon gamma Signaling Positively Regulates Hematopoietic Stem Cell Emergence

    PubMed Central

    Sawamiphak, Suphansa; Kontarakis, Zacharias; Stainier, Didier Y.R.

    2014-01-01

    Summary Vertebrate hematopoietic stem cells (HSCs) emerge in the aorta-gonad-mesonephros (AGM) region from “hemogenic” endothelium. Here we show that the pro-inflammatory cytokine Ifn-γ and its receptor Crfb17 positively regulate HSC development in zebrafish. This regulation does not appear to modulate the proliferation or survival of HSCs or endothelial cells, but rather the endothelial to HSC transition. Notch signaling and blood flow positively regulate the expression of ifng and crfb17 in the AGM. Notably, Ifn-γ overexpression partially rescues the HSC loss observed in the absence of blood flow or Notch signaling. Importantly, Ifn-γ signaling acts cell-autonomously to control the endothelial to HSC transition. Ifn-γ activates Stat3, an atypical transducer of Ifn-γ signaling, in the AGM, and Stat3 inhibition decreases HSC formation. Together, our findings uncover a developmental role for an inflammatory cytokine and place its action downstream of Notch signaling and blood flow to control Stat3 activation and HSC emergence. PMID:25490269

  8. 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

  9. 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

  10. Regulation of NMDA-receptor synaptic transmission by Wnt signaling

    PubMed Central

    Cerpa, Waldo; Gambrill, Abigail; Inestrosa, Nibaldo C.; Barria, Andres

    2011-01-01

    Wnt ligands are secreted glycoproteins controlling gene expression and cytoskeleton reorganization involved in embryonic development of the nervous system. However, their role in later stages of brain development, particularly in the regulation of established synaptic connections is not known. We found that Wnt-5a acutely and specifically up-regulates synaptic NMDAR currents in rat hippocampal slices facilitating induction of LTP, a cellular model of learning and memory. This effect requires an increase in postsynaptic Ca2+ and activation of non-canonical downstream effectors of the Wnt signaling pathway. In contrast, Wnt-7a, an activator of the canonical Wnt signaling pathway, has no effect on NMDAR mediated synaptic transmission. Moreover, endogenous Wnt ligands are necessary to maintain basal NMDAR synaptic transmission adjusting the threshold for synaptic potentiation. This novel role for Wnt ligands provides a mechanism for Wnt signaling to acutely modulate synaptic plasticity and brain function in later stages of development and in the mature organism. PMID:21715611

  11. Regulation of cross-talk in yeast MAPK signaling pathways.

    PubMed

    Saito, Haruo

    2010-12-01

    MAP kinase (MAPK) modules are conserved three-kinase cascades that serve central roles in intracellular signal transduction in eukaryotic cells. MAPK pathways of different inputs and outputs use overlapping sets of signaling components. In yeast, for example, three MAPK pathways (pheromone response, filamentous growth response, and osmostress adaptation) all use the same Ste11 MAPK kinase kinase (MAPKKK). How undesirable leakage of signal, or cross-talk, is prevented between these pathways has been a subject of intensive study. This review discusses recent findings from yeast that indicate that there is no single mechanism, but that a combination of four general strategies (docking interactions, scaffold proteins, cross-pathway inhibition, and kinetic insulation) are utilized for the prevention of cross-talk between any two MAPK modules.

  12. WNT/β-Catenin Signaling Regulates Multiple Steps of Myogenesis by Regulating Step-Specific Targets

    PubMed Central

    Suzuki, Akiko; Pelikan, Richard C.

    2015-01-01

    Molecules involved in WNT/β-catenin signaling show specific spatiotemporal expression and play vital roles in myogenesis; however, it is still largely unknown how WNT/β-catenin signaling regulates each step of myogenesis. Here, we show that WNT/β-catenin signaling can control diverse biological processes of myogenesis by regulating step-specific molecules. In order to identify the temporally specific roles of WNT/β-catenin signaling molecules in muscle development and homeostasis, we used in vitro culture systems for both primary mouse myoblasts and C2C12 cells, which can differentiate into myofibers. We found that a blockade of WNT/β-catenin signaling in the proliferating cells decreases proliferation activity, but does not induce cell death, through the regulation of genes cyclin A2 (Ccna2) and cell division cycle 25C (Cdc25c). During muscle differentiation, the inhibition of WNT/β-catenin signaling blocks myoblast fusion through the inhibition of the Fermitin family homolog 2 (Fermt2) gene. Blocking WNT/β-catenin signaling in the well-differentiated myofibers results in the failure of maintenance of their structure by disruption of cadherin/β-catenin/actin complex formation, which plays a crucial role in connecting a myofiber's cytoskeleton to the surrounding extracellular matrix. Thus, our results indicate that WNT/β-catenin signaling can regulate multiple steps of myogenesis, including cell proliferation, myoblast fusion, and homeostasis, by targeting step-specific molecules. PMID:25755281

  13. WNT/β-Catenin Signaling Regulates Multiple Steps of Myogenesis by Regulating Step-Specific Targets.

    PubMed

    Suzuki, Akiko; Pelikan, Richard C; Iwata, Junichi

    2015-05-01

    Molecules involved in WNT/β-catenin signaling show specific spatiotemporal expression and play vital roles in myogenesis; however, it is still largely unknown how WNT/β-catenin signaling regulates each step of myogenesis. Here, we show that WNT/β-catenin signaling can control diverse biological processes of myogenesis by regulating step-specific molecules. In order to identify the temporally specific roles of WNT/β-catenin signaling molecules in muscle development and homeostasis, we used in vitro culture systems for both primary mouse myoblasts and C2C12 cells, which can differentiate into myofibers. We found that a blockade of WNT/β-catenin signaling in the proliferating cells decreases proliferation activity, but does not induce cell death, through the regulation of genes cyclin A2 (Ccna2) and cell division cycle 25C (Cdc25c). During muscle differentiation, the inhibition of WNT/β-catenin signaling blocks myoblast fusion through the inhibition of the Fermitin family homolog 2 (Fermt2) gene. Blocking WNT/β-catenin signaling in the well-differentiated myofibers results in the failure of maintenance of their structure by disruption of cadherin/β-catenin/actin complex formation, which plays a crucial role in connecting a myofiber's cytoskeleton to the surrounding extracellular matrix. Thus, our results indicate that WNT/β-catenin signaling can regulate multiple steps of myogenesis, including cell proliferation, myoblast fusion, and homeostasis, by targeting step-specific molecules.

  14. Wnt signaling in the regulation of adult hippocampal neurogenesis

    PubMed Central

    Varela-Nallar, Lorena; Inestrosa, Nibaldo C.

    2013-01-01

    In the adult brain new neurons are continuously generated mainly in two regions, the subventricular zone (SVZ) of the lateral ventricles and the subgranular zone (SGZ) in the hippocampal dentate gyrus. In the SGZ, radial neural stem cells (NSCs) give rise to granule cells that integrate into the hippocampal circuitry and are relevant for the plasticity of the hippocampus. Loss of neurogenesis impairs learning and memory, suggesting that this process is important for adult hippocampal function. Adult neurogenesis is tightly regulated by multiple signaling pathways, including the canonical Wnt/β-catenin pathway. This pathway plays important roles during the development of neuronal circuits and in the adult brain it modulates synaptic transmission and plasticity. Here, we review current knowledge on the regulation of adult hippocampal neurogenesis by the Wnt/β-catenin signaling cascade and the potential mechanisms involved in this regulation. Also we discuss the evidence supporting that the canonical Wnt pathway is part of the signaling mechanisms involved in the regulation of neurogenesis in different physiological conditions. Finally, some unsolved questions regarding the Wnt-mediated regulation of neurogenesis are discussed. PMID:23805076

  15. Temporal regulation of Dpp signaling output in the Drosophila wing

    PubMed Central

    O’Keefe, David D.; Thomas, Sean; Edgar, Bruce A.; Buttitta, Laura

    2014-01-01

    Background The Decapentaplegic (Dpp) signaling pathway is used in many developmental and homeostatic contexts, each time resulting in cellular responses particular to that biological niche. The flexibility of Dpp signaling is clearly evident in epithelial cells of the Drosophila wing imaginal disc. During larval stages of development Dpp functions as a morphogen, patterning the wing developmental field and stimulating tissue growth. A short time later however, as wing-epithelial cells exit the cell cycle and begin to differentiate, Dpp is a critical determinant of vein-cell fate. It is likely that the Dpp signaling pathway regulates different sets of target genes at these two developmental time points. Results To identify mechanisms that temporally control the transcriptional output of Dpp signaling in this system, we have taken a gene expression profiling approach. We identified genes affected by Dpp signaling at late larval or early pupal developmental time points, thereby identifying patterning- and differentiation-specific downstream targets, respectively. Conclusions Analysis of target genes and transcription factor binding sites associated with these groups of genes revealed potential mechanisms by which target-gene specificity of the Dpp signaling pathway is temporally regulated. In addition, this approach revealed novel mechanisms by which Dpp affects the cellular differentiation of wing-veins. PMID:24591046

  16. 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.

  17. 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

  18. Retinoid signaling regulates breast cancer stem cell differentiation

    PubMed Central

    Ginestier, Christophe; Wicinski, Julien; Cervera, Nathalie; Monville, Florence; Finetti, Pascal; Bertucci, François; Wicha, Max S.; Birnbaum, Daniel; Charafe-Jauffret, Emmanuelle

    2010-01-01

    The cancer stem cell (CSC) hypothesis implicates the development of new therapeutic approaches to target the CSC population. Characterization of the pathways that regulate CSCs activity will facilitate the development of targeted therapies. We recently reported that the enzymatic activity of ALDH1, as measured by the ALDELFUOR assay, can be utilized to isolate normal and malignant breast stem cells in both primary tumors and cell lines. In this study, utilizing a tumorsphere assay, we have demonstrated the role of retinoid signaling in the regulation of breast CSCs self-renewal and differentiation. Utilizing the gene set enrichment analysis (GSEA) algorithm we identified gene sets and pathways associated with retinoid signaling. These pathways regulate breast CSCs biology and their inhibition may provide novel therapeutic approaches to target breast CSCs. PMID:19806016

  19. 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.

  20. Sensitivity control through attenuation of signal transfer efficiency by negative regulation of cellular signalling.

    PubMed

    Toyoshima, Yu; Kakuda, Hiroaki; Fujita, Kazuhiro A; Uda, Shinsuke; Kuroda, Shinya

    2012-03-13

    Sensitivity is one of the hallmarks of biological and pharmacological responses. However, the principle of controlling sensitivity remains unclear. Here we theoretically analyse a simple biochemical reaction and find that the signal transfer efficiency of the transient peak amplitude attenuates depending on the strength of negative regulation. We experimentally find that many signalling pathways in various cell lines, including the Akt and ERK pathways, can be approximated by simple biochemical reactions and that the same property of the attenuation of signal transfer efficiency was observed for such pathways. Because of this property, a downstream molecule should show higher sensitivity to an activator and lower sensitivity to an inhibitor than an upstream molecule. Indeed, we experimentally verify that S6, which lies downstream of Akt, shows lower sensitivity to an epidermal growth factor receptor inhibitor than Akt. Thus, cells can control downstream sensitivity through the attenuation of signal transfer efficiency by changing the expression level of negative regulators.

  1. Regulation of Chemokine Signal Integration by Activator of G-Protein Signaling 4 (AGS4)

    PubMed Central

    Robichaux, William G.; Branham-O’Connor, Melissa; Hwang, Il-Young; Vural, Ali; Kehrl, Johne H.

    2017-01-01

    Activator of G-protein signaling 4 (AGS4)/G-protein signaling modulator 3 (Gpsm3) contains three G-protein regulatory (GPR) motifs, each of which can bind Gαi-GDP free of Gβγ. We previously demonstrated that the AGS4-Gαi interaction is regulated by seven transmembrane-spanning receptors (7-TMR), which may reflect direct coupling of the GPR-Gαi module to the receptor analogous to canonical Gαβγ heterotrimer. We have demonstrated that the AGS4-Gαi complex is regulated by chemokine receptors in an agonist-dependent manner that is receptor-proximal. As an initial approach to investigate the functional role(s) of this regulated interaction in vivo, we analyzed leukocytes, in which AGS4/Gpsm3 is predominantly expressed, from AGS4/Gpsm3-null mice. Loss of AGS4/Gpsm3 resulted in mild but significant neutropenia and leukocytosis. Dendritic cells, T lymphocytes, and neutrophils from AGS4/Gpsm3-null mice also exhibited significant defects in chemoattractant-directed chemotaxis and extracellular signal-regulated kinase activation. An in vivo peritonitis model revealed a dramatic reduction in the ability of AGS4/Gpsm3-null neutrophils to migrate to primary sites of inflammation. Taken together, these data suggest that AGS4/Gpsm3 is required for proper chemokine signal processing in leukocytes and provide further evidence for the importance of the GPR-Gαi module in the regulation of leukocyte function. PMID:28062526

  2. Notch signaling regulates gastric antral LGR5 stem cell function.

    PubMed

    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

    2015-10-14

    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.

  3. Strigolactone regulates shoot development through a core signalling pathway

    PubMed Central

    Müller, Dörte

    2016-01-01

    ABSTRACT Strigolactones are a recently identified class of hormone that regulate multiple aspects of plant development. The DWARF14 (D14) α/β fold protein has been identified as a strigolactone receptor, which can act through the SCFMAX2 ubiquitin ligase, but the universality of this mechanism is not clear. Multiple proteins have been suggested as targets for strigolactone signalling, including both direct proteolytic targets of SCFMAX2, and downstream targets. However, the relevance and importance of these proteins to strigolactone signalling in many cases has not been fully established. Here we assess the contribution of these targets to strigolactone signalling in adult shoot developmental responses. We find that all examined strigolactone responses are regulated by SCFMAX2 and D14, and not by other D14-like proteins. We further show that all examined strigolactone responses likely depend on degradation of SMXL proteins in the SMXL6 clade, and not on the other proposed proteolytic targets BES1 or DELLAs. Taken together, our results suggest that in the adult shoot, the dominant mode of strigolactone signalling is D14-initiated, MAX2-mediated degradation of SMXL6-related proteins. We confirm that the BRANCHED1 transcription factor and the PIN-FORMED1 auxin efflux carrier are plausible downstream targets of this pathway in the regulation of shoot branching, and show that BRC1 likely acts in parallel to PIN1. PMID:27793831

  4. Intracellular LINGO-1 negatively regulates Trk neurotrophin receptor signaling.

    PubMed

    Meabon, James S; de Laat, Rian; Ieguchi, Katsuaki; Serbzhinsky, Dmitry; Hudson, Mark P; Huber, B Russel; Wiley, Jesse C; Bothwell, Mark

    2016-01-01

    Neurotrophins, essential regulators of many aspects of neuronal differentiation and function, signal via four receptors, p75, TrkA, TrkB and TrkC. The three Trk paralogs are members of the LIG superfamily of membrane proteins, which share extracellular domains consisting of leucine-rich repeat and C2 Ig domains. Another LIG protein, LINGO-1 has been reported to bind and influence signaling of p75 as well as TrkA, TrkB and TrkC. Here we examine the manner in which LINGO-1 influences the function of TrkA, TrkB and TrkC. We report that Trk activation promotes Trk association with LINGO-1, and that this association promotes Trk degradation by a lysosomal mechanism. This mechanism resembles the mechanism by which another LIG protein, LRIG1, promotes lysosomal degradation of receptor tyrosine kinases such as the EGF receptor. We present evidence indicating that the Trk/LINGO-1 interaction occurs, in part, within recycling endosomes. We show that a mutant form of LINGO-1, with much of the extracellular domain deleted, has the capacity to enhance TrkA signaling in PC12 cells, possibly by acting as an inhibitor of Trk down-regulation by full length LINGO-1. We propose that LINGO-1 functions as a negative feedback regulator of signaling by cognate receptor tyrosine kinases including TrkA, TrkB and TrkC.

  5. 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

  6. Shank Modulates Postsynaptic Wnt Signaling to Regulate Synaptic Development

    PubMed Central

    Akbergenova, Yulia; Cho, Richard W.; Baas-Thomas, Maximilien S.; Littleton, J. Troy

    2016-01-01

    Prosap/Shank scaffolding proteins regulate the formation, organization, and plasticity of excitatory synapses. Mutations in SHANK family genes are implicated in autism spectrum disorder and other neuropsychiatric conditions. However, the molecular mechanisms underlying Shank function are not fully understood, and no study to date has examined the consequences of complete loss of all Shank proteins in vivo. Here we characterize the single Drosophila Prosap/Shank family homolog. Shank is enriched at the postsynaptic membrane of glutamatergic neuromuscular junctions and controls multiple parameters of synapse biology in a dose-dependent manner. Both loss and overexpression of Shank result in defects in synaptic bouton number and maturation. We find that Shank regulates a noncanonical Wnt signaling pathway in the postsynaptic cell by modulating the internalization of the Wnt receptor Fz2. This study identifies Shank as a key component of synaptic Wnt signaling, defining a novel mechanism for how Shank contributes to synapse maturation during neuronal development. SIGNIFICANCE STATEMENT Haploinsufficiency for SHANK3 is one of the most prevalent monogenic causes of autism spectrum disorder, making it imperative to understand how the Shank family regulates neurodevelopment and synapse function. We created the first animal model lacking all Shank proteins and used the Drosophila neuromuscular junction, a model glutamatergic synapse, to characterize the role of Shank at synapses. We identified a novel function of Shank in synapse maturation via regulation of Wnt signaling in the postsynaptic cell. PMID:27225771

  7. Multicriteria mapping of stakeholder preferences in regulating nanotechnology

    PubMed Central

    2010-01-01

    In order to facilitate stakeholder discussions on how to regulate nanotechnology, the opensource program multicriteria mapping (MCM) was used to structure 26 interviews with stakeholders in the USA. MCM offers a systematic part quantitative, part qualitative approach to clarify why some regulatory options (bans, moratoriums, voluntary measures, etc.) were deemed to be acceptable/unacceptable by various stakeholders and which criteria stakeholders used to evaluate the different regulatory options. Adopting an incremental approach and implementing a new regulatory framework was evaluated as the best options whereas a complete ban and no additional regulation of nanotechnology were found to be the least favorable. Criteria applied differed substantially among stakeholders and included social, ethical, regulatory, environmental, and health issues. Opinions on future regulation seem far less polarized than expected and it seems that stakeholders would welcome a combination of voluntary measures, an incremental approach and forming of a new regulatory framework. Electronic supplementary material The online version of this article (doi:10.1007/s11051-010-0006-3) contains supplementary material, which is available to authorized users. PMID:21170118

  8. Regulators of G protein signalling proteins in the human myometrium.

    PubMed

    Ladds, Graham; Zervou, Sevasti; Vatish, Manu; Thornton, Steven; Davey, John

    2009-05-21

    The contractile state of the human myometrium is controlled by extracellular signals that promote relaxation or contraction. Many of these signals function through G protein-coupled receptors at the cell surface, stimulating heterotrimeric G proteins and leading to changes in the activity of effector proteins responsible for bringing about the response. G proteins can interact with multiple receptors and many different effectors and are key players in the response. Regulators of G protein signalling (RGS) proteins are GTPase activating proteins for heterotrimeric G proteins and help terminate the signal. Little is known about the function of RGS proteins in human myometrium and we have therefore analysed transcript levels for RGS proteins at various stages of pregnancy (non-pregnant, preterm, term non-labouring, term labouring). RGS2 and RGS5 were the most abundantly expressed isolates in each of the patient groups. The levels of RGS4 and RGS16 (and to a lesser extent RGS2 and RGS14) increased in term labouring samples relative to the other groups. Yeast two-hybrid analysis and co-immunoprecipitation in myometrial cells revealed that both RGS2 and RGS5 interact directly with the cytoplasmic tail of the oxytocin receptor, suggesting they might help regulate signalling through this receptor.

  9. Regulation of Golgi signaling and trafficking by the KDEL receptor.

    PubMed

    Cancino, Jorge; Jung, Juan E; Luini, Alberto

    2013-10-01

    Intracellular membrane transport involves the well-coordinated engagement of a series of organelles and molecular machineries that ensure that proteins are delivered to their correct cellular locations according to their function. To maintain the homeostasis of the secretory system, the fluxes of membranes and protein across the transport compartments must be precisely balanced. This control should rely on a mechanism that senses the movement of the traffic and generates the required homeostatic response. Due to its central position in the secretory pathway and to the large amounts of signaling molecules associated with it, the Golgi complex represents the ideal candidate for this regulation. The generation of autonomous signaling by the Golgi complex in response to the arrival of cargo from the endoplasmic reticulum (ER) has been experimentally addressed only in recent years. These studies have revealed that cargo moving from the ER to the Golgi activates a series of signaling pathways, the functional significance of which appears to be to maintain the homeostasis of the Golgi complex and to activate Golgi trafficking according to internal demand. We have termed this regulatory mechanism the Golgi control system. A key player in this Golgi control system is the KDEL receptor, which has previously been shown to retrieve chaperones back to the endoplasmic reticulum and more recently to behave as a signaling receptor. Here, we discuss the particular role of KDEL receptor signaling in the regulation of important pathways involved in the maintenance of the homeostasis of the transport apparatus, and in particular, of the Golgi complex.

  10. Notch Signaling Pathway Regulates Progesterone Secretion in Murine Luteal Cells.

    PubMed

    Wang, Jing; Liu, Shuangmei; Peng, Lichao; Dong, Qiming; Bao, Riqiang; Lv, Qiulan; Tang, Min; Hu, Chuan; Li, Gang; Liang, Shangdong; Zhang, Chunping

    2015-10-01

    Notch signaling is an evolutionarily conserved pathway, which involves in various cell life activities. Other studies and our report showed that the Notch signaling plays very important role in follicle development in mammalian ovaries. In luteal cells, Notch ligand, delta-like ligand 4, is involved in normal luteal vasculature. In this study, murine luteal cells were cultured in vitro and treated with Notch signaling inhibitors, L-658,458 and N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycinet-butyl ester (DAPT). We found that L-658,458 and DAPT treatment decrease basal and human chorionic gonadotropin (hCG)-stimulated progesterone secretion. On the contrary, overexpression of intracellular domain of Notch3 increased basal and hCG-stimulated progesterone secretion. Further studies demonstrated that Notch signaling regulated the expression of steroidogenic acute regulatory protein and CYP11A, 2 key enzymes for progesterone synthesis. In conclusion, Notch signaling plays important role in regulating progesterone secretion in murine luteal cells.

  11. 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

  12. 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

  13. 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.

  14. 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

  15. Noncosmological signal contributions to the COBE DMR anisotropy maps

    NASA Astrophysics Data System (ADS)

    Bennett, C. L.; Hinshaw, G.; Banday, A.; Kogut, A.; Wright, E. L.; Loewenstein, K.; Cheng, E. S.

    1993-09-01

    We examine the COBE Differential Microwave Radiometer (DMR) data for evidence of noncosmological source contributions. The DMR maps are cross-correlated with maps of rich clusters, extragalactic IRAS sources, HEAO 1 A-2 X-ray emission, and 5 GHz radio sources. We limit the rms contributions from these sources on a 7 deg angular scale to less than 10 micro-K (95 percent confidence level) in the DMR maps, although the LMC probably contributes about 50 micro-K to a limited region of the sky. Thus, our previous interpretation that the fluctuations in the COBE DMR data are most likely due to cosmic fluctuations at the surface of last scattering remains intact. The Comptonization parameter for hot electrons traced by rich clusters is limited to delta(y) less than 2 x 10 exp -6 (95 percent confidence level) averaged over the 7 deg DMR beam.

  16. PUF-8 negatively regulates RAS/MAPK signalling to promote differentiation of C. elegans germ cells

    PubMed Central

    Vaid, Samir; Ariz, Mohd; Chaturbedi, Amaresh; Kumar, Ganga Anil; Subramaniam, Kuppuswamy

    2013-01-01

    Signals that promote germ cell self-renewal by preventing premature meiotic entry are well understood. However, signals that control mitotic proliferation to promote meiotic differentiation have not been well characterized. In Caenorhabditis elegans, GLP-1 Notch signalling promotes the proliferative fate by preventing premature meiotic entry. The germline niche cell, which is the source of the ligand for GLP-1, spatially restricts GLP-1 signalling and thus enables the germ cells that have moved away from the niche to enter meiosis. Here, we show that the suppression of RAS/MAP kinase signalling in the mitotic and meiotic-entry regions is essential for the regulation of the mitosis-meiosis switch by niche signalling. We provide evidence that the conserved PUF family RNA-binding protein PUF-8 and the RAS GAP protein GAP-3 function redundantly to suppress the LET-60 RAS in the mitotic and meiotic entry regions. Germ cells missing both PUF-8 and GAP-3 proliferate in an uncontrolled fashion and fail to undergo meiotic development. MPK-1, the MAP kinase downstream of the LET-60 RAS, is prematurely activated in these cells; downregulation of MPK-1 activation eliminates tumours and restores differentiation. Our results further reveal that PUF-8 negatively regulates LET-60 expression at a post-transcriptional step. LET-60 is misexpressed in the puf-8(-) mutant germlines and PUF-8 physically interacts with the let-60 3′ UTR. Furthermore, PUF-8 suppresses let-60 3′ UTR-mediated expression in the germ cells that are transitioning from the mitotic to meiotic fate. These results reveal that PUF-8-mediated inhibition of the RAS/MAPK pathway is essential for mitotic-to-meiotic fate transition. PMID:23487310

  17. 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.

  18. Redox regulation of cancer metastasis: molecular signaling and therapeutic opportunities.

    PubMed

    Yang, Wenyong; Zou, Linzhi; Huang, Canhua; Lei, Yunlong

    2014-08-01

    Cancer metastasis is the major cause of cancer-related mortality. Accumulated evidence has shown that high-metastasis potential cancer cells have more reactive oxygen species (ROS) accumulation compared with low-metastasis potential cancer cells. ROS can function as second messengers to regulate multiple cancer metastasis-related signaling pathways via reversible oxidative posttranslational modifications of cysteine in key redox-sensitive proteins, which leads to the structural and functional change of these proteins. Because ROS can promote cancer metastasis, therapeutic strategies aiming at inducing/reducing cellular ROS level or targeting redox sensors involved in metastasis hold great potential in developing new efficient approaches for anticancer therapy. In this review, we summarize recent findings on regulation of tumor metastasis by key redox sensors and describe the potential of targeting redox signaling pathways for cancer therapy.

  19. 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.

  20. Gap Junctional Regulation of Signal Transduction in Bone Cells

    PubMed Central

    Buo, Atum M.; Stains, Joseph P.

    2014-01-01

    The role of gap junctions, particularly that of connexin43 (Cx43), has become an area of increasing interest in bone physiology. An abundance of studies have shown that Cx43 influences the function of osteoblasts and osteocytes, which ultimately impacts bone mass acquisition and skeletal homeostasis. However, the molecular details underlying how Cx43 regulates bone are only coming into focus and have proven to be more complex than originally thought. In this review, we focus on the diverse molecular mechanisms by which Cx43 gap junctions and hemichannels regulate cell signaling pathways, gene expression, mechanotransduction and cell survival in bone cells. This review will highlight key signaling factors that have been identified as downstream effectors of Cx43 and the impact of these pathways on distinct osteoblast and osteocyte functions. PMID:24486014

  1. PDGFRalphaalpha signaling is regulated through the primary cilium in fibroblasts.

    PubMed

    Schneider, Linda; Clement, Christian A; Teilmann, Stefan C; Pazour, Gregory J; Hoffmann, Else K; Satir, Peter; Christensen, Søren T

    2005-10-25

    Recent findings show that cilia are sensory organelles that display specific receptors and ion channels, which transmit signals from the extracellular environment via the cilium to the cell to control tissue homeostasis and function. Agenesis of primary cilia or mislocation of ciliary signal components affects human pathologies, such as polycystic kidney disease and disorders associated with Bardet-Biedl syndrome. Primary cilia are essential for hedgehog ligand-induced signaling cascade regulating growth and patterning. Here, we show that the primary cilium in fibroblasts plays a critical role in growth control via platelet-derived growth factor receptor alpha (PDGFRalpha), which localizes to the primary cilium during growth arrest in NIH3T3 cells and primary cultures of mouse embryonic fibroblasts. Ligand-dependent activation of PDGFRalphaalpha is followed by activation of Akt and the Mek1/2-Erk1/2 pathways, with Mek1/2 being phosphorylated within the cilium and at the basal body. Fibroblasts derived from Tg737(orpk) mutants fail to form normal cilia and to upregulate the level of PDGFRalpha; PDGF-AA fails to activate PDGFRalphaalpha and the Mek1/2-Erk1/2 pathway. Signaling through PDGFRbeta, which localizes to the plasma membrane, is maintained at comparable levels in wild-type and mutant cells. We propose that ciliary PDGFRalphaalpha signaling is linked to tissue homeostasis and to mitogenic signaling pathways.

  2. 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

  3. Canonical Wnt Signaling Regulates Atrioventricular Junction Programming and Electrophysiological Properties

    PubMed Central

    Gillers, Benjamin S; Chiplunkar, Aditi; Aly, Haytham; Valenta, Tomas; Basler, Konrad; Christoffels, Vincent M.; Efimov, Igor R; Boukens, Bastiaan J; Rentschler, Stacey

    2014-01-01

    Rationale Proper patterning of the atrioventricular canal (AVC) is essential for delay of electrical impulses between atria and ventricles, and defects in AVC maturation can result in congenital heart disease. Objective To determine the role of canonical Wnt signaling in the myocardium during AVC development. Methods and Results We utilized a novel allele of β-catenin that preserves β-catenin’s cell adhesive functions but disrupts canonical Wnt signaling, allowing us to probe the effects of Wnt loss of function independently. We show that loss of canonical Wnt signaling in the myocardium results in tricuspid atresia with hypoplastic right ventricle associated with loss of AVC myocardium. In contrast, ectopic activation of Wnt signaling was sufficient to induce formation of ectopic AV junction-like tissue as assessed by morphology, gene expression, and electrophysiologic criteria. Aberrant AVC development can lead to ventricular preexcitation, a characteristic feature of Wolff-Parkinson-White syndrome. We demonstrate that postnatal activation of Notch signaling downregulates canonical Wnt targets within the AV junction. Stabilization of β-catenin protein levels can rescue Notch-mediated ventricular preexcitation and dysregulated ion channel gene expression. Conclusions Our data demonstrate that myocardial canonical Wnt signaling is an important regulator of AVC maturation and electrical programming upstream of Tbx3. Our data further suggests that ventricular preexcitation may require both morphologic patterning defects, as well as myocardial lineage reprogramming, to allow robust conduction across accessory pathway tissue. PMID:25599332

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

    PubMed

    Melech-Bonfil, Shiri; Sessa, Guido

    2010-11-01

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

  5. Mesolimbic leptin signaling negatively regulates cocaine-conditioned reward.

    PubMed

    Shen, M; Jiang, C; Liu, P; Wang, F; Ma, L

    2016-12-06

    The regulatory mechanisms underlying the response to addictive drugs are complex, and increasing evidence indicates that there is a role for appetite-regulating pathways in substance abuse. Leptin, an important adipose hormone that regulates energy balance and appetite, exerts its physiological functions via leptin receptors. However, the role of leptin signaling in regulating the response to cocaine remains unclear. Here we examined the potential role of leptin signaling in cocaine reward using a conditioned place preference (CPP) procedure. Our results showed that inhibition of leptin signaling by intracerebroventricular infusion of the leptin receptor (LepR) antagonist SMLA during cocaine conditioning increased the cocaine-CPP and upregulated the level of dopamine and its metabolites in the nucleus accumbens (NAc). We then selectively knocked down the LepR in the mesolimbic ventral tegmental area (VTA), NAc core and central amygdala (CeA) by injecting AAV-Cre into Lepr(flox/flox) mice. LepR deletion in the VTA increased the dopamine levels in the NAc and enhanced the cocaine-conditioned reward. LepR deletion in the NAc core enhanced the cocaine-conditioned reward and impaired the effect of the D2-dopamine receptor on cocaine-CPP, whereas LepR deletion in the CeA had no effect on cocaine-CPP but increased the anxiety level of mice. In addition, prior exposure to saccharin increased LepR mRNA and STAT3 phosphorylation in the NAc and VTA and impaired cocaine-CPP. These results indicate that leptin signaling is critically involved in cocaine-conditioned reward and the regulation of drug reward by a natural reward and that these effects are dependent on mesolimbic LepR.

  6. Mesolimbic leptin signaling negatively regulates cocaine-conditioned reward

    PubMed Central

    Shen, M; Jiang, C; Liu, P; Wang, F; Ma, L

    2016-01-01

    The regulatory mechanisms underlying the response to addictive drugs are complex, and increasing evidence indicates that there is a role for appetite-regulating pathways in substance abuse. Leptin, an important adipose hormone that regulates energy balance and appetite, exerts its physiological functions via leptin receptors. However, the role of leptin signaling in regulating the response to cocaine remains unclear. Here we examined the potential role of leptin signaling in cocaine reward using a conditioned place preference (CPP) procedure. Our results showed that inhibition of leptin signaling by intracerebroventricular infusion of the leptin receptor (LepR) antagonist SMLA during cocaine conditioning increased the cocaine-CPP and upregulated the level of dopamine and its metabolites in the nucleus accumbens (NAc). We then selectively knocked down the LepR in the mesolimbic ventral tegmental area (VTA), NAc core and central amygdala (CeA) by injecting AAV-Cre into Leprflox/flox mice. LepR deletion in the VTA increased the dopamine levels in the NAc and enhanced the cocaine-conditioned reward. LepR deletion in the NAc core enhanced the cocaine-conditioned reward and impaired the effect of the D2-dopamine receptor on cocaine-CPP, whereas LepR deletion in the CeA had no effect on cocaine-CPP but increased the anxiety level of mice. In addition, prior exposure to saccharin increased LepR mRNA and STAT3 phosphorylation in the NAc and VTA and impaired cocaine-CPP. These results indicate that leptin signaling is critically involved in cocaine-conditioned reward and the regulation of drug reward by a natural reward and that these effects are dependent on mesolimbic LepR. PMID:27922639

  7. Autocrine and Paracrine Hh Signaling Regulate Prostate Development

    DTIC Science & Technology

    2010-09-01

    development and tumorigenesis (13). The forkhead transcription factor Foxe1 was established as a downstream target of the Shh pathway in hair follicle morpho...in the epithelium of the developing prostate; activate Hh target genes expressed in the surrounding mesenchyme and influence prostate ductal growth...postanatally. We propose this temporal growth effects is mediated by the discordant regulation of a subset of target genes by Hh signaling in the prenatal and

  8. Cortical sensory map rearrangement after spinal cord injury: fMRI responses linked to Nogo signalling.

    PubMed

    Endo, Toshiki; Spenger, Christian; Tominaga, Teiji; Brené, Stefan; Olson, Lars

    2007-11-01

    Cortical sensory maps can reorganize in the adult brain in an experience-dependent manner. We monitored somatosensory cortical reorganization after sensory deafferentation using functional magnetic resonance imaging (fMRI) in rats subjected to complete transection of the mid-thoracic spinal cord. Cortical representation in response to spared forelimb stimulation was observed to enlarge and invade adjacent sensory-deprived hind limb territory in the primary somatosensory cortex as early as 3 days after injury. Functional MRI also demonstrated long-term cortical plasticity accompanied by increased thalamic activation. To support the notion that alterations of cortical neuronal circuitry after spinal cord injury may underlie the fMRI changes, we quantified transcriptional activities of several genes related to cortical plasticity including the Nogo receptor (NgR), its co-receptor LINGO-1 and brain derived neurotrophic factor (BDNF), using in situ hybridization. We demonstrate that NgR and LINGO-1 are down-regulated specifically in cortical areas deprived of sensory input and in adjacent cortex from 1 day after injury, while BDNF is up-regulated. Our results demonstrate that cortical neurons react to sensory deprivation by decreasing transcriptional activities of genes encoding the Nogo receptor components in the sensory deprived and the anatomically adjacent non-deprived area. Combined with the BDNF up-regulation, these changes presumably allow structural changes in the neuropil. Our observations therefore suggest an involvement of Nogo signalling in cortical activity-dependent plasticity in the somatosensory system. In spinal cord injury, cortical reorganization as shown here can become a disadvantage, much like the situation in amblyopia or phantom sensation. Successful strategies to repair sensory pathways at the spinal cord level may not lead to proper reestablishment of cortical connections, once deprived hind limb cortical areas have been reallocated to forelimb

  9. Phosphorylation-dependent regulation of Notch1 signaling: the fulcrum of Notch1 signaling.

    PubMed

    Lee, Hye-Jin; Kim, Mi-Yeon; Park, Hee-Sae

    2015-08-01

    Notch signaling plays a pivotal role in cell fate determination, cellular development, cellular self-renewal, tumor progression, and has been linked to developmental disorders and carcinogenesis. Notch1 is activated through interactions with the ligands of neighboring cells, and acts as a transcriptional activator in the nucleus. The Notch1 intracellular domain (Notch1-IC) regulates the expression of target genes related to tumor development and progression. The Notch1 protein undergoes modification after translation by posttranslational modification enzymes. Phosphorylation modification is critical for enzymatic activation, complex formation, degradation, and subcellular localization. According to the nuclear cycle, Notch1-IC is degraded by E3 ligase, FBW7 in the nucleus via phosphorylation-dependent degradation. Here, we summarize the Notch signaling pathway, and resolve to understand the role of phosphorylation in the regulation of Notch signaling as well as to understand its relation to cancer.

  10. 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.

  11. Early induction of CREB activation and CREB-regulating signalling by antidepressants.

    PubMed

    Tardito, Daniela; Musazzi, Laura; Tiraboschi, Ettore; Mallei, Alessandra; Racagni, Giorgio; Popoli, Maurizio

    2009-11-01

    Converging evidence points to adaptive changes in neuroplasticity and gene expression as mediators of therapeutic action of antidepressants. Activation of cAMP response-element binding protein (CREB) and CREB-regulating signalling are considered main effectors in these mechanisms. We analysed the temporal profile of intracellular changes induced by antidepressants, by measuring activation of major CREB-regulating signalling cascades and activation (Ser133 phosphorylation) of CREB. The main aims of the study were to investigate how these different variables are modulated with time, whether stronger activation of signalling cascades corresponds to stronger activation of CREB, and whether these changes are different in distinct brain areas. Rat groups were treated for 1, 2 or 3 wk with the antidepressants fluoxetine or reboxetine; in additional groups drug treatment was followed by a washout week (3+1). Activation of CREB and major effectors in signalling cascades were analysed by Western blot analysis with phospho-antibodies, in nuclear and cytosolic fractions from hippocampus and prefrontal/frontal cortex (P/FC). Surprisingly, CREB activation was already maximal after 1-wk treatment. In hippocampus early and stronger CREB activation was consistent with early and stronger activation of signalling. For both drugs, the profile of activation in P/FC was different from that observed in hippocampus. The results also showed that, contrary to the activatory role of MAP-ERKs and CaM kinase IV, nuclear alphaCaM kinase II was inactivated in parallel with activation of CREB.

  12. Estrogen receptors regulate innate immune cells and signaling pathways.

    PubMed

    Kovats, Susan

    2015-04-01

    Humans show strong sex differences in immunity to infection and autoimmunity, suggesting sex hormones modulate immune responses. Indeed, receptors for estrogens (ERs) regulate cells and pathways in the innate and adaptive immune system, as well as immune cell development. ERs are ligand-dependent transcription factors that mediate long-range chromatin interactions and form complexes at gene regulatory elements, thus promoting epigenetic changes and transcription. ERs also participate in membrane-initiated steroid signaling to generate rapid responses. Estradiol and ER activity show profound dose- and context-dependent effects on innate immune signaling pathways and myeloid cell development. While estradiol most often promotes the production of type I interferon, innate pathways leading to pro-inflammatory cytokine production may be enhanced or dampened by ER activity. Regulation of innate immune cells and signaling by ERs may contribute to the reported sex differences in innate immune pathways. Here we review the recent literature and highlight several molecular mechanisms by which ERs regulate the development or functional responses of innate immune cells.

  13. Regulation of FcεRI signaling by lipid phosphatases.

    PubMed

    Kuhny, Marcel; Zorn, Carolin N; Huber, Michael

    2014-01-01

    Mast cells (MCs) are tissue-resident sentinels of hematopoietic origin that play a prominent role in allergic diseases. They express the high-affinity receptor for IgE (FcεRI), which when cross-linked by multivalent antigens triggers the release of preformed mediators, generation of arachidonic acid metabolites, and the synthesis of cytokines and chemokines. Stimulation of the FcεRI with increasing antigen concentrations follows a characteristic bell-shaped dose-responses curve. At high antigen concentrations, the so-called supra-optimal conditions, repression of FcεRI-induced responses is facilitated by activation and incorporation of negative signaling regulators. In this context, the SH2-containing inositol-5'-phosphatase, SHIP1, has been demonstrated to be of particular importance. SHIP1 with its catalytic and multiple protein interaction sites provides several layers of control for FcεRI signaling. Regulation of SHIP1 function occurs on various levels, e.g., protein expression, receptor and membrane recruitment, competition for protein-protein interaction sites, and activating modifications enhancing the phosphatase function. Apart from FcεRI-mediated signaling, SHIP1 can be activated by diverse unrelated receptor systems indicating its involvement in the regulation of antigen-dependent cellular responses by autocrine feedback mechanisms or tissue-specific and/or (patho-) physiologically determined factors. Thus, pharmacologic engagement of SHIP1 may represent a beneficial strategy for patients suffering from acute or chronic inflammation or allergies.

  14. 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.

  15. Cannabinoid receptor signaling regulates liver development and metabolism

    PubMed Central

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

    2016-01-01

    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. PMID:26884397

  16. Regulation of interferon gamma signaling by suppressors of cytokine signaling and regulatory T cells.

    PubMed

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

    2013-12-18

    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.

  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. Hydrogen sulfide anion regulates redox signaling via electrophile sulfhydration

    PubMed Central

    Nishida, Motohiro; Sawa, Tomohiro; Kitajima, Naoyuki; Ono, Katsuhiko; Inoue, Hirofumi; Ihara, Hideshi; Motohashi, Hozumi; Yamamoto, Masayuki; Suematsu, Makoto; Kurose, Hitoshi; van der Vliet, Albert; Freeman, Bruce A; Shibata, Takahiro; Uchida, Koji; Kumagai, Yoshito; Akaike, Takaaki

    2014-01-01

    An emerging aspect of redox signaling is the pathway mediated by electrophilic byproducts, such as nitrated cyclic nucleotide (for example, 8-nitroguanosine 3′,5′-cyclic monophosphate (8-nitro-cGMP)) and nitro or keto derivatives of unsaturated fatty acids, generated via reactions of inflammation-related enzymes, reactive oxygen species, nitric oxide and secondary products. Here we report that enzymatically generated hydrogen sulfide anion (HS−) regulates the metabolism and signaling actions of various electrophiles. HS− reacts with electrophiles, best represented by 8-nitro-cGMP, via direct sulfhydration and modulates cellular redox signaling. The relevance of this reaction is reinforced by the significant 8-nitro-cGMP formation in mouse cardiac tissue after myocardial infarction that is modulated by alterations in HS− biosynthesis. Cardiac HS−, in turn, suppresses electrophile-mediated H-Ras activation and cardiac cell senescence, contributing to the beneficial effects of HS− on myocardial infarction–associated heart failure. Thus, this study reveals HS−-induced electrophile sulfhydration as a unique mechanism for regulating electrophile-mediated redox signaling. PMID:22772154

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

    PubMed Central

    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.; West, James D.; Blackwell, Timothy S.; Lawson, William E.

    2015-01-01

    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. PMID:26637636

  20. 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.

  1. Insulin signaling regulates neurite growth during metamorphic neuronal remodeling

    PubMed Central

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

    2014-01-01

    Summary 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. PMID:24357229

  2. GABA Not Only a Neurotransmitter: Osmotic Regulation by GABAAR Signaling

    PubMed Central

    Cesetti, Tiziana; Ciccolini, Francesca; Li, Yuting

    2012-01-01

    Mature macroglia and almost all neural progenitor types express γ-aminobutyric (GABA) A receptors (GABAARs), whose activation by ambient or synaptic GABA, leads to influx or efflux of chloride (Cl−) depending on its electro-chemical gradient (ECl). Since the flux of Cl− is indissolubly associated to that of osmotically obliged water, GABAARs regulate water movements by modulating ion gradients. In addition, since water movements also occur through specialized water channels and transporters, GABAAR signaling could affect the movement of water by regulating the function of the channels and transporters involved, thereby affecting not only the direction of the water fluxes but also their dynamics. We will here review recent observations indicating that in neural cells GABAAR-mediated osmotic regulation affects the cellular volume thereby activating multiple intracellular signaling mechanisms important for cell proliferation, maturation, and survival. In addition, we will discuss evidence that the osmotic regulation exerted by GABA may contribute to brain water homeostasis in physiological and in pathological conditions causing brain edema, in which the GABAergic transmission is often altered. PMID:22319472

  3. CD23 can negatively regulate B-cell receptor signaling

    PubMed Central

    Liu, Chaohong; Richard, Katharina; Wiggins, Melvin; Zhu, Xiaoping; Conrad, Daniel H.; Song, Wenxia

    2016-01-01

    CD23 has been implicated as a negative regulator of IgE and IgG antibody responses. However, whether CD23 has any role in B-cell activation remains unclear. We examined the expression of CD23 in different subsets of peripheral B cells and the impact of CD23 expression on the early events of B-cell receptor (BCR) activation using CD23 knockout (KO) mice. We found that in addition to marginal zone B cells, mature follicular B cells significantly down regulate the surface expression level of CD23 after undergoing isotype switch and memory B-cell differentiation. Upon stimulation with membrane-associated antigen, CD23 KO causes significant increases in the area of B cells contacting the antigen-presenting membrane and the magnitude of BCR clustering. This enhanced cell spreading and BCR clustering is concurrent with increases in the levels of phosphorylation of tyrosine and Btk, as well as the levels of F-actin and phosphorylated Wiskott Aldrich syndrome protein, an actin nucleation promoting factor, in the contract zone of CD23 KO B cells. These results reveal a role of CD23 in the negative regulation of BCR signaling in the absence of IgE immune complex and suggest that CD23 down-regulates BCR signaling by influencing actin-mediated BCR clustering and B-cell morphological changes. PMID:27181049

  4. 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

  5. Regulation of atypical MAP kinases ERK3 and ERK4 by the phosphatase DUSP2

    PubMed Central

    Perander, Maria; Al-Mahdi, Rania; Jensen, Thomas C.; Nunn, Jennifer A. L.; Kildalsen, Hanne; Johansen, Bjarne; Gabrielsen, Mads; Keyse, Stephen M.; Seternes, Ole-Morten

    2017-01-01

    The atypical MAP kinases ERK3 and ERK4 are activated by phosphorylation of a serine residue lying within the activation loop signature sequence S-E-G. However, the regulation of ERK3 and ERK4 phosphorylation and activity is poorly understood. Here we report that the inducible nuclear dual-specificity MAP kinase phosphatase (MKP) DUSP2, a known regulator of the ERK and p38 MAPKs, is unique amongst the MKP family in being able to bind to both ERK3 and ERK4. This interaction is mediated by a conserved common docking (CD) domain within the carboxyl-terminal domains of ERK3 and ERK4 and the conserved kinase interaction motif (KIM) located within the non-catalytic amino terminus of DUSP2. This interaction is direct and results in the dephosphorylation of ERK3 and ERK4 and the stabilization of DUSP2. In the case of ERK4 its ability to stabilize DUSP2 requires its kinase activity. Finally, we demonstrate that expression of DUSP2 inhibits ERK3 and ERK4-mediated activation of its downstream substrate MK5. We conclude that the activity of DUSP2 is not restricted to the classical MAPK pathways and that DUSP2 can also regulate the atypical ERK3/4-MK5 signalling pathway in mammalian cells. PMID:28252035

  6. 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.

  7. 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

  8. Extracellular signal-related kinase positively regulates ataxia telangiectasia mutated, homologous recombination repair, and the DNA damage response.

    PubMed

    Golding, Sarah E; Rosenberg, Elizabeth; Neill, Steven; Dent, Paul; Povirk, Lawrence F; Valerie, Kristoffer

    2007-02-01

    The accurate joining of DNA double-strand breaks by homologous recombination repair (HRR) is critical to the long-term survival of the cell. The three major mitogen-activated protein (MAP) kinase (MAPK) signaling pathways, extracellular signal-regulated kinase (ERK), p38, and c-Jun-NH(2)-kinase (JNK), regulate cell growth, survival, and apoptosis. To determine the role of MAPK signaling in HRR, we used a human in vivo I-SceI-based repair system. First, we verified that this repair platform is amenable to pharmacologic manipulation and show that the ataxia telangiectasia mutated (ATM) kinase is critical for HRR. The ATM-specific inhibitor KU-55933 compromised HRR up to 90% in growth-arrested cells, whereas this effect was less pronounced in cycling cells. Then, using well-characterized MAPK small-molecule inhibitors, we show that ERK1/2 and JNK signaling are important positive regulators of HRR in growth-arrested cells. On the other hand, inhibition of the p38 MAPK pathway generated an almost 2-fold stimulation of HRR. When ERK1/2 signaling was stimulated by oncogenic RAF-1, an approximately 2-fold increase in HRR was observed. KU-55933 partly blocked radiation-induced ERK1/2 phosphorylation, suggesting that ATM regulates ERK1/2 signaling. Furthermore, inhibition of MAP/ERK kinase (MEK)/ERK signaling resulted in severely reduced levels of phosphorylated (S1981) ATM foci but not gamma-H2AX foci, and suppressed ATM phosphorylation levels >85% throughout the cell cycle. Collectively, these results show that MAPK signaling positively and negatively regulates HRR in human cells. More specifically, ATM-dependent signaling through the RAF/MEK/ERK pathway is critical for efficient HRR and for radiation-induced ATM activation, suggestive of a regulatory feedback loop between ERK and ATM.

  9. Paradoxical signaling regulates structural plasticity in dendritic spines

    PubMed Central

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

    2016-01-01

    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

  10. 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

  11. Stra13 regulates satellite cell activation by antagonizing Notch signaling

    PubMed Central

    Sun, Hong; Li, Li; Vercherat, Cécile; Gulbagci, Neriman Tuba; Acharjee, Sujata; Li, Jiali; Chung, Teng-Kai; Thin, Tin Htwe; Taneja, Reshma

    2007-01-01

    Satellite cells play a critical role in skeletal muscle regeneration in response to injury. Notch signaling is vital for satellite cell activation and myogenic precursor cell expansion but inhibits myogenic differentiation. Thus, precise spatial and temporal regulation of Notch activity is necessary for efficient muscle regeneration. We report that the basic helix-loop-helix transcription factor Stra13 modulates Notch signaling in regenerating muscle. Upon injury, Stra13−/− mice exhibit increased cellular proliferation, elevated Notch signaling, a striking regeneration defect characterized by degenerated myotubes, increased mononuclear cells, and fibrosis. Stra13−/− primary myoblasts also exhibit enhanced Notch activity, increased proliferation, and defective differentiation. Inhibition of Notch signaling ex vivo and in vivo ameliorates the phenotype of Stra13−/− mutants. We demonstrate in vitro that Stra13 antagonizes Notch activity and reverses the Notch-imposed inhibition of myogenesis. Thus, Stra13 plays an important role in postnatal myogenesis by attenuating Notch signaling to reduce myoblast proliferation and promote myogenic differentiation. PMID:17502421

  12. 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

  13. Mapping condition-dependent regulation of lipid metabolism in Saccharomyces cerevisiae.

    PubMed

    Jewett, Michael C; Workman, Christopher T; Nookaew, Intawat; Pizarro, Francisco A; Agosin, Eduardo; Hellgren, Lars I; Nielsen, Jens

    2013-11-06

    Lipids play a central role in cellular function as constituents of membranes, as signaling molecules, and as storage materials. Although much is known about the role of lipids in regulating specific steps of metabolism, comprehensive studies integrating genome-wide expression data, metabolite levels, and lipid levels are currently lacking. Here, we map condition-dependent regulation controlling lipid metabolism in Saccharomyces cerevisiae by measuring 5636 mRNAs, 50 metabolites, 97 lipids, and 57 (13)C-reaction fluxes in yeast using a three-factor full-factorial design. Correlation analysis across eight environmental conditions revealed 2279 gene expression level-metabolite/lipid relationships that characterize the extent of transcriptional regulation in lipid metabolism relative to major metabolic hubs within the cell. To query this network, we developed integrative methods for correlation of multi-omics datasets that elucidate global regulatory signatures. Our data highlight many characterized regulators of lipid metabolism and reveal that sterols are regulated more at the transcriptional level than are amino acids. Beyond providing insights into the systems-level organization of lipid metabolism, we anticipate that our dataset and approach can join an emerging number of studies to be widely used for interrogating cellular systems through the combination of mathematical modeling and experimental biology.

  14. Mapping Condition-Dependent Regulation of Lipid Metabolism in Saccharomyces cerevisiae

    PubMed Central

    Jewett, Michael C.; Workman, Christopher T.; Nookaew, Intawat; Pizarro, Francisco A.; Agosin, Eduardo; Hellgren, Lars I.; Nielsen, Jens

    2013-01-01

    Lipids play a central role in cellular function as constituents of membranes, as signaling molecules, and as storage materials. Although much is known about the role of lipids in regulating specific steps of metabolism, comprehensive studies integrating genome-wide expression data, metabolite levels, and lipid levels are currently lacking. Here, we map condition-dependent regulation controlling lipid metabolism in Saccharomyces cerevisiae by measuring 5636 mRNAs, 50 metabolites, 97 lipids, and 57 13C-reaction fluxes in yeast using a three-factor full-factorial design. Correlation analysis across eight environmental conditions revealed 2279 gene expression level-metabolite/lipid relationships that characterize the extent of transcriptional regulation in lipid metabolism relative to major metabolic hubs within the cell. To query this network, we developed integrative methods for correlation of multi-omics datasets that elucidate global regulatory signatures. Our data highlight many characterized regulators of lipid metabolism and reveal that sterols are regulated more at the transcriptional level than are amino acids. Beyond providing insights into the systems-level organization of lipid metabolism, we anticipate that our dataset and approach can join an emerging number of studies to be widely used for interrogating cellular systems through the combination of mathematical modeling and experimental biology. PMID:24062529

  15. Epithelial SCAP/INSIG/SREBP Signaling Regulates Multiple Biological Processes during Perinatal Lung Maturation

    PubMed Central

    Bridges, James P.; Schehr, Angelica; Wang, Yanhua; Huo, Liya; Besnard, Valérie; Ikegami, Machiko; Whitsett, Jeffrey A.; Xu, Yan

    2014-01-01

    Pulmonary surfactant is required for lung function at birth and throughout postnatal life. Defects in the surfactant system are associated with common pulmonary disorders including neonatal respiratory distress syndrome and acute respiratory distress syndrome in children and adults. Lipogenesis is essential for the synthesis of pulmonary surfactant by type II epithelial cells lining the alveoli. This study sought to identify the role of pulmonary epithelial SREBP, a transcriptional regulator of cellular lipid homeostasis, during a critical time period of perinatal lung maturation in the mouse. Genome wide mRNA expression profiling of lung tissue from transgenic mice with epithelial-specific deletions of Scap (ScapΔ/Δ, resulting in inactivation of SREBP signaling) or Insig1 and Insig2 (Insig1/2Δ/Δ, resulting in activation of SREBP signaling) was assessed. Differentially expressed genes responding to SREBP perturbations were identified and subjected to functional enrichment analysis, pathway mapping and literature mining to predict upstream regulators and transcriptional networks regulating surfactant lipid homeostasis. Through comprehensive data analysis and integration, time dependent effects of epithelial SCAP/INSIG/SREBP deletion and defined SCAP/INSIG/SREBP-associated genes, bioprocesses and downstream pathways were identified. SREBP signaling influences epithelial development, cell death and cell proliferation at E17.5, while primarily influencing surfactant physiology, lipid/sterol synthesis, and phospholipid transport after birth. SREBP signaling integrated with the Wnt/β-catenin and glucocorticoid receptor signaling pathways during perinatal lung maturation. SREBP regulates perinatal lung lipogenesis and maturation through multiple mechanisms by interactions with distinct sets of regulatory partners. PMID:24806461

  16. Arabidopsis MAP3K16 and Other Salt-Inducible MAP3Ks Regulate ABA Response Redundantly

    PubMed Central

    Choi, Seo-wha; Lee, Seul-bee; Na, Yeon-ju; Jeung, Sun-geum; Kim, Soo Young

    2017-01-01

    In the Arabidopsis genome, approximately 80 MAP3Ks (mitogen-activated protein kinase kinase kinases) have been identified. However, only a few of them have been characterized, and the functions of most MAP3Ks are largely unknown. In this paper, we report the function of MAP3K16 and several other MAP3Ks, MAP3K14/15/17/18, whose expression is salt-inducible. We prepared MAP3K16 overexpression (OX) lines and analyzed their phenotypes. The result showed that the transgenic plants were ABA-insensitive during seed germination and cotyledon greening stage but their root growth was ABA-hypersensitive. The OX lines were more susceptible to water-deficit condition at later growth stage in soil. A MAP3K16 knockout (KO) line, on the other hand, exhibited opposite phenotypes. In similar transgenic analyses, we found that MAP3K14/15/17/18 OX and KO lines displayed similar phenotypes to those of MA3K16, suggesting the functional redundancy among them. MAP3K16 possesses in vitro kinase activity, and we carried out two-hybrid analyses to identify MAP3K16 substrates. Our results indicate that MAP3K16 interacts with MKK3 and the negative regulator of ABA response, ABR1, in yeast. Furthermore, MAP3K16 recombinant protein could phosphorylate MKK3 and ABR1, suggesting that they might be MAP3K16 substrates. Collectively, our results demonstrate that MAP3K16 and MAP3K14/15/17/18 are involved in ABA response, playing negative or positive roles depending on developmental stage and that MAP3K16 may function via MKK3 and ABR1. PMID:28292003

  17. 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.

  18. 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.

  19. The Drosophila rolled locus encodes a MAP kinase required in the sevenless signal transduction pathway.

    PubMed Central

    Biggs, W H; Zavitz, K H; Dickson, B; van der Straten, A; Brunner, D; Hafen, E; Zipursky, S L

    1994-01-01

    Mitogen-activated protein (MAP) kinases have been proposed to play a critical role in receptor tyrosine kinase (RTK)-mediated signal transduction pathways. Although genetic and biochemical studies of RTK pathways in Caenorhabditis elegans, Drosophila melanogaster and mammals have revealed remarkable similarities, a genetic requirement for MAP kinases in RTK signaling has not been established. During retinal development in Drosophila, the sevenless (Sev) RTK is required for development of the R7 photoreceptor cell. Components of the signal transduction pathway activated by Sev in the R7 precursor include proteins encoded by the gap1, drk, Sos, ras1 and raf loci. In this report we present evidence that a Drosophila MAP kinase, ERK-A, is encoded by the rolled locus and is required downstream of raf in the Sev signal transduction pathway. Images PMID:8157002

  20. The Spectrin cytoskeleton regulates the Hippo signalling pathway

    PubMed Central

    Fletcher, Georgina C; Elbediwy, Ahmed; Khanal, Ichha; Ribeiro, Paulo S; Tapon, Nic; Thompson, Barry J

    2015-01-01

    The Spectrin cytoskeleton is known to be polarised in epithelial cells, yet its role remains poorly understood. Here, we show that the Spectrin cytoskeleton controls Hippo signalling. In the developing Drosophila wing and eye, loss of apical Spectrins (alpha/beta-heavy dimers) produces tissue overgrowth and mis-regulation of Hippo target genes, similar to loss of Crumbs (Crb) or the FERM-domain protein Expanded (Ex). Apical beta-heavy Spectrin binds to Ex and co-localises with it at the apical membrane to antagonise Yki activity. Interestingly, in both the ovarian follicular epithelium and intestinal epithelium of Drosophila, apical Spectrins and Crb are dispensable for repression of Yki, while basolateral Spectrins (alpha/beta dimers) are essential. Finally, the Spectrin cytoskeleton is required to regulate the localisation of the Hippo pathway effector YAP in response to cell density human epithelial cells. Our findings identify both apical and basolateral Spectrins as regulators of Hippo signalling and suggest Spectrins as potential mechanosensors. PMID:25712476

  1. Spatial regulation of Raf kinase signaling by RKTG

    PubMed Central

    Feng, Lin; Xie, Xiaoduo; Ding, Qiurong; Luo, Xiaolin; He, Jing; Fan, Fengjuan; Liu, Weizhong; Wang, Zhenzhen; Chen, Yan

    2007-01-01

    Subcellular compartmentalization has become an important theme in cell signaling such as spatial regulation of Ras by RasGRP1 and MEK/ERK by Sef. Here, we report spatial regulation of Raf kinase by RKTG (Raf kinase trapping to Golgi). RKTG is a seven-transmembrane protein localized at the Golgi apparatus. RKTG expression inhibits EGF-stimulated ERK and RSK phosphorylation, blocks NGF-mediated PC12 cell differentiation, and antagonizes Ras- and Raf-1-stimulated Elk-1 transactivation. Through interaction with Raf-1, RKTG changes the localization of Raf-1 from cytoplasm to the Golgi apparatus, blocks EGF-stimulated Raf-1 membrane translocation, and reduces the interaction of Raf-1 with Ras and MEK1. In RKTG-null mice, the basal ERK phosphorylation level is increased in the brain and liver. In RKTG-deleted mouse embryonic fibroblasts, EGF-induced ERK phosphorylation is enhanced. Collectively, our results reveal a paradigm of spatial regulation of Raf kinase by RKTG via sequestrating Raf-1 to the Golgi apparatus and thereby inhibiting the ERK signaling pathway. PMID:17724343

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

    PubMed Central

    Shen, Meng-Ru; Chou, Cheng-Yang; Browning, Joseph A; Wilkins, Robert J; Ellory, J Clive

    2001-01-01

    This study was aimed at identifying the signalling pathways involved in the activation of volume-regulatory mechanisms of human cervical cancer cells. 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. 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. 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. 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. 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

  3. 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...

  4. Regulation of neuronal PKA signaling through AKAP targeting dynamics.

    PubMed

    Dell'Acqua, Mark L; Smith, Karen E; Gorski, Jessica A; Horne, Eric A; Gibson, Emily S; Gomez, Lisa L

    2006-07-01

    Central to organization of signaling pathways are scaffolding, anchoring and adaptor proteins that mediate localized assembly of multi-protein complexes containing receptors, second messenger-generating enzymes, kinases, phosphatases, and substrates. At the postsynaptic density (PSD) of excitatory synapses, AMPA (AMPAR) and NMDA (NMDAR) glutamate receptors are linked to signaling proteins, the actin cytoskeleton, and synaptic adhesion molecules on dendritic spines through a network of scaffolding proteins that may play important roles regulating synaptic structure and receptor functions in synaptic plasticity underlying learning and memory. AMPARs are rapidly recruited to dendritic spines through NMDAR activation during induction of long-term potentiation (LTP) through pathways that also increase the size and F-actin content of spines. Phosphorylation of AMPAR-GluR1 subunits by the cAMP-dependent protein kinase (PKA) helps stabilize AMPARs recruited during LTP. In contrast, induction of long-term depression (LTD) leads to rapid calcineurin-protein phosphatase 2B (CaN) mediated dephosphorylation of PKA-phosphorylated GluR1 receptors, endocytic removal of AMPAR from synapses, and a reduction in spine size. However, mechanisms for coordinately regulating AMPAR localization, phosphorylation, and synaptic structure by PKA and CaN are not well understood. A kinase-anchoring protein (AKAP) 79/150 is a PKA- and CaN-anchoring protein that is linked to NMDARs and AMPARs through PSD-95 and SAP97 membrane-associated guanylate kinase (MAGUK) scaffolds. Importantly, disruption of PKA-anchoring in neurons and functional analysis of GluR1-MAGUK-AKAP79 complexes in heterologous cells suggests that AKAP79/150-anchored PKA and CaN may regulate AMPARs in LTD. In the work presented at the "First International Meeting on Anchored cAMP Signaling Pathways" (Berlin-Buch, Germany, October 15-16, 2005), we demonstrate that AKAP79/150 is targeted to dendritic spines by an N-terminal basic

  5. Wnt signaling regulates pulp volume and dentin thickness

    PubMed Central

    Lim, Won Hee; Liu, Bo; Cheng, Du; Hunter, Daniel J; Zhong, Zhendong; Ramos, Daniel M; Williams, Bart O; Sharpe, Paul T; Bardet, Claire; Mah, Su-jung; Helms, Jill A

    2015-01-01

    Odontoblasts, cementoblasts, ameloblasts and osteoblasts all form mineralized tissues in the craniofacial complex, and all these cell types exhibit active Wnt signaling during postnatal life. We set out to understand the functions of this Wnt signaling, by evaluating the phenotypes of mice in which the essential Wnt chaperone protein, Wingless was eliminated. The deletion of Wls was restricted to cells expressing Osteocalcin, which in addition to osteoblasts includes odontoblasts, cementoblasts, and ameloblasts. Dentin, cementum, enamel, and bone all formed in OCN-Cre;Wlsfl/fl mice but their homeostasis was dramatically affected. The most notable feature was a significant increase in dentin volume and density. We attribute this gain in dentin volume to a Wnt-mediated mis-regulation of Runx2. Normally, Wnt signaling stimulates Runx2, which in turn inhibits DSP; this inhibition must be relieved for odontoblasts to differentiate. In OCN-Cre;Wlsfl/fl mice, Wnt pathway activation is reduced and Runx2 levels decline. The Runx2-mediated repression of DSP is relieved and odontoblast differentiation is accordingly enhanced. This study demonstrates the importance of Wnt signaling in the homeostasis of mineralized tissues of the craniofacial complex. PMID:23996396

  6. Mnk Kinases in Cytokine Signaling and Regulation of Cytokine Responses

    PubMed Central

    Joshi, Sonali; Platanias, Leonidas C.

    2013-01-01

    The kinases Mnk1 and Mnk2 are activated downstream of the p38 MAPK and MEK/ERK signaling pathways. Extensive work over the years has shown that these kinases control phosphorylation of the eukaryotic initiation factor 4E (eIF4E) and regulate engagement of other effector elements, including hnRNPA1 and PSF. Mnk kinases are ubiquitously expressed and play critical roles in signaling for various cytokine receptors, while there is emerging evidence that they have important functions as mediators of pro-inflammatory cytokine production. In this review the mechanisms of activation of MNK pathways by cytokine receptors are addressed and their roles in diverse cytokine-dependent biological processes are reviewed. The clinical-translational implications of such work and the relevance of future development of specific MNK inhibitors for the treatment of malignancies and auto-immune disorders are discussed. PMID:23710261

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

    PubMed

    Kuhrt, David; Wojchowski, Don M

    2015-06-04

    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.

  8. AKT Regulates BRCA1 Stability in Response to Hormone Signaling

    PubMed Central

    Nelson, Andrew C.; Lyons, Traci R.; Young, Christian D.; Hansen, Kirk C.; Anderson, Steven M.; Holt, Jeffrey T.

    2015-01-01

    BRCA1, with its binding partner BARD1, regulates the cellular response to DNA damage in multiple tissues, yet inherited mutations within BRCA1 result specifically in breast and ovarian cancers. This observation, along with several other lines of evidence, suggests a functional relationship may exist between hormone signaling and BRCA1 function. Our data demonstrates that AKT activation promotes the expression of BRCA1 in response to estrogen and IGF-1 receptor signaling. Further, we have identified a novel AKT phosphorylation site in BRCA1 at S694 which is responsive to activation of these signaling pathways. This rapid increase in BRCA1 protein levels appears to occur independently of new protein synthesis and treatment with the clinically utilized proteasome inhibitor bortezomib similarly leads to a rapid increase in BRCA1 protein levels. Together, these data suggest that AKT phosphorylation of BRCA1 increases total protein expression by preventing proteasomal degradation. AKT activation also appears to support nuclear localization of BRCA1, and co-expression of activated AKT with BRCA1 decreases radiation sensitivity, suggesting this interaction has functional consequences for BRCA1's role in DNA repair. We conclude that AKT regulates BRCA1 protein stability and function through direct phosphorylation of BRCA1. Further, the responsiveness of the AKT-BRCA1 regulatory pathway to hormone signaling may, in part, underlie the tissue specificity of BRCA1 mutant cancers. Pharmacological targets within this pathway could provide strategies for modulation of BRCA1 protein, which may prove therapeutically beneficial for the treatment of breast and ovarian cancers. PMID:20085797

  9. 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.

  10. 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.

  11. AlzPathway: a comprehensive map of signaling pathways of Alzheimer’s disease

    PubMed Central

    2012-01-01

    Background Alzheimer’s disease (AD) is the most common cause of dementia among the elderly. To clarify pathogenesis of AD, thousands of reports have been accumulating. However, knowledge of signaling pathways in the field of AD has not been compiled as a database before. Description Here, we have constructed a publicly available pathway map called “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 an AD pathway map using CellDesigner. AlzPathway is currently composed of 1347 molecules and 1070 reactions in neuron, brain blood barrier, presynaptic, postsynaptic, astrocyte, and microglial cells and their cellular localizations. AlzPathway is available as both the SBML (Systems Biology Markup Language) map for CellDesigner and the high resolution image map. AlzPathway is also available as a web service (online map) based on Payao system, a community-based, collaborative web service platform for pathway model curation, enabling continuous updates by AD researchers. Conclusions AlzPathway is the first comprehensive map of intra, inter and extra cellular AD signaling pathways which can enable mechanistic deciphering of AD pathogenesis. The AlzPathway map is accessible at http://alzpathway.org/. PMID:22647208

  12. 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

  13. TGFβ signaling regulates lipogenesis in human sebaceous glands cells

    PubMed Central

    2013-01-01

    Background Sebaceous glands are components of the skin essential for its normal lubrication by the production of sebum. This contributes to skin health and more importantly is crucial for the skin barrier function. A mechanistic understanding of sebaceous gland cells growth and differentiation has lagged behind that for keratinocytes, partly because of a lack of an in vitro model that can be used for experimental manipulation. Methods We have developed an in vitro culture model to isolate and grow primary human sebocytes without transformation that display functional characteristics of sebocytes. We used this novel method to probe the effect of Transforming Growth Factor β (TGFβ) signaling on sebocyte differentiation, by examining the expression of genes involved in lipogenesis upon treatment with TGFβ1. We also repressed TGFβ signaling through knockdown of the TGFβ Receptor II to address if the effect of TGFβ activation is mediated via canonical Smad signal transduction. Results We find that activation of the TGFβ signaling pathway is necessary and sufficient for maintaining sebocytes in an undifferentiated state. The presence of TGFβ ligand triggered decreased expression in genes required for the production of characteristics sebaceous lipids and for sebocyte differentiation such as FADS2 and PPARγ, thereby decreasing lipid accumulation through the TGFβ RII-Smad2 dependent pathway. Conclusion TGFβ signaling plays an essential role in sebaceous gland regulation by maintaining sebocytes in an undifferentiated state. This data was generated using a novel method for human sebocyte culture, which is likely to prove generally useful in investigations of sebaceous gland growth and differentiation. These findings open a new paradigm in human skin biology with important implications for skin therapies. PMID:23343495

  14. 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.

  15. 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

    2010-11-13

    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.

  16. 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.

  17. Insulin signaling and the regulation of insect diapause

    PubMed Central

    Sim, Cheolho; Denlinger, David L.

    2013-01-01

    A rich chapter in the history of insect endocrinology has focused on hormonal control of diapause, especially the major roles played by juvenile hormones (JHs), ecdysteroids, and the neuropeptides that govern JH and ecdysteroid synthesis. More recently, experiments with adult diapause in Drosophila melanogaster and the mosquito Culex pipiens, and pupal diapause in the flesh fly Sarcophaga crassipalpis provide strong evidence that insulin signaling is also an important component of the regulatory pathway leading to the diapause phenotype. Insects produce many different insulin-like peptides (ILPs), and not all are involved in the diapause response; ILP-1 appears to be the one most closely linked to diapause in C. pipiens. Many steps in the pathway leading from perception of daylength (the primary environmental cue used to program diapause) to generation of the diapause phenotype remain unknown, but the role for insulin signaling in mosquito diapause appears to be upstream of JH, as evidenced by the fact that application of exogenous JH can rescue the effects of knocking down expression of ILP-1 or the Insulin Receptor. Fat accumulation, enhancement of stress tolerance, and other features of the diapause phenotype are likely linked to the insulin pathway through the action of a key transcription factor, FOXO. This review highlights many parallels for the role of insulin signaling as a regulator in insect diapause and dauer formation in the nematode Caenorhabditis elegans. PMID:23885240

  18. 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

  19. [Structural Life Science towards the Regulation of Selective GPCR Signaling].

    PubMed

    Kobayashi, Takuya

    2016-01-01

    G protein-coupled receptors (GPCRs) are the largest family of receptors in the human genome. They are involved in many diseases and also the target of approximately 30% of all modern medicinal drugs. GPCRs respond to a broad spectrum of chemical entities, ranging from photons, protons, and calcium ions to small organic molecules (including odorants and neurotransmitters), peptides, and glycoproteins. Many GPCRs are members of closely related subfamilies that respond to the same hormone or neurotransmitter. However, they have different physiologic functions based on the cells in which they are expressed and the different signaling pathways that they exploit (e.g., coupling through heterotrimeric G-proteins such as Gs, Gi, and Gq, as well as β-arrestins). Antibody fragments including Fab and Fv can effectively stabilize and crystallize membrane proteins. However, using the mouse hybridoma technology it has been difficult to develop monoclonal antibodies that can recognize conformational epitopes of native GPCRs. We have recently succeeded in developing antibodies against native GPCRs using this technology in combination with our improved immunization and screening methods. In this symposium review, I present a successful example of prostaglandin E2 receptor (one of the GPCRs) crystallization using antibody fragments. To avoid several adverse effects of current therapeutics, it is essential to understand the molecular mechanism of GPCR signaling in a monomeric, dimeric, or oligomeric state. Also, we are interested in selectively regulating GPCR signaling via functional antibodies developed using our methods and/or the designed small organic molecules depending on the GPCR structure.

  20. Nontranscriptional regulation of NLRP3 inflammasome signaling by IL-4

    PubMed Central

    Hwang, Inhwa; Yang, Jungmin; Hong, Sujeong; Lee, Eun Ju; Lee, Seung-Hyo; Fernandes-Alnemri, Teresa; Alnemri, Emad S; Yu, Je-Wook

    2015-01-01

    Th2 cytokine IL-4 has been previously shown to suppress the production of proinflammatory cytokines in monocytes. However, the underlying molecular mechanism by which IL-4 signaling antagonizes proinflammatory responses is poorly characterized. In particular, whether IL-4 can modulate inflammasome signaling is unknown. Here, we provide evidence that IL-4 suppresses NLRP3-dependent caspase-1 activation and the subsequent IL-1β secretion but does not inhibit AIM2- or NLRC4-dependent caspase-1 activation in THP-1 and mouse bone marrow-derived macrophages. Upon LPS or LPS/ATP stimulation, IL-4 markedly inhibited the assembly of NLRP3 inflammasome, including NLRP3-dependent ASC oligomerization, NLRP3-ASC interaction, and NLRP3 speck-like oligomeric structure formation. The negative regulation of NLRP3 inflammasome by IL-4 was not due to the impaired mRNA or protein production of NLRP3 and proinflammatory cytokines. Supporting this observation, IL-4 attenuated NLRP3 inflammasome activation even in reconstituted NLRP3-expressing macrophages in which NLRP3 expression is not transcriptionally regulated by TLR-NF-κB signaling. Furthermore, the IL-4-mediated suppression of NLRP3 inflammasome was independent of STAT6-dependent transcription and mitochondrial ROS. Instead, IL-4 inhibited subcellular redistribution of NLRP3 into mitochondria and microtubule polymerization upon NLRP3-activating stimulation. Our results collectively suggest that IL-4 could suppress NLRP3 inflammasome activation in a transcription-independent manner, thus providing an endogenous regulatory machinery to prevent excessive inflammasome activation. PMID:25601272

  1. The sweet side of AMPK signaling: regulation of GFAT1.

    PubMed

    Scott, John W; Oakhill, Jonathan S

    2017-03-23

    Maintaining a steady balance between nutrient supply and energy demand is essential for all living organisms and is achieved through the dynamic control of metabolic processes that produce and consume adenosine-5'-triphosphate (ATP), the universal currency of energy in all cells. A key sensor of cellular energy is the adenosine-5'-monophosphate (AMP)-activated protein kinase (AMPK), which is the core component of a signaling network that regulates energy and nutrient metabolism. AMPK is activated by metabolic stresses that decrease cellular ATP, and functions to restore energy balance by orchestrating a switch in metabolism away from anabolic pathways toward energy-generating catabolic processes. A new study published in a recent issue of Biochemical Journal by Zibrova et al. shows that glutamine:fructose-6-phosphate amidotransferase-1 (GFAT1), the rate-limiting enzyme of the hexosamine biosynthesis pathway (HBP), is a physiological substrate of AMPK. The HBP is an offshoot of the glycolytic pathway that drives the synthesis of uridine-5'-diphospho-N-acetylglucosamine, the requisite donor metabolite needed for dynamic β-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) of cellular proteins. O-GlcNAcylation is a nutrient-sensitive post-translational modification that, like phosphorylation, regulates numerous intracellular processes. Zibrova et al. show that inhibitory phosphorylation of the GFAT1 residue Ser243 by AMPK in response to physiological or small-molecule activators leads to a reduction in cellular protein O-GlcNAcylation. Further work revealed that AMPK-dependent phosphorylation of GFAT1 promotes angiogenesis in endothelial cells. This elegant study demonstrates that the AMPK-GFAT1 signaling axis serves as an important communication point between two nutrient-sensitive signaling pathways and is likely to play a significant role in controlling physiological processes in many other tissues.

  2. Proteomic mapping of ER-PM junctions identifies STIMATE as regulator of Ca2+ influx

    PubMed Central

    Jing, Ji; He, Lian; Sun, Aomin; Quintana, Ariel; Ding, Yuehe; Ma, Guolin; Tan, Peng; Liang, Xiaowen; Zheng, Xiaolu; Chen, Liangyi; Shi, Xiaodong; Zhang, Shenyuan L.; Zhong, Ling; Huang, Yun; Dong, Meng-Qiu; Walker, Cheryl L.; Hogan, Patrick G.; Wang, Youjun; Zhou, Yubin

    2015-01-01

    Specialized junctional sites that connect the plasma membrane (PM) and endoplasmic reticulum (ER) play critical roles in controlling lipid metabolism and Ca2+ signaling1–4. Store operated Ca2+ entry mediated by dynamic STIM1-ORAI1 coupling represents a classical molecular event occurring at ER-PM junctions, but the protein composition and how previously-unrecognized protein regulators facilitate this process remain ill-defined. Using a combination of spatially-restricted biotin-labelling in situ coupled with mass spectrometry5, 6 and a secondary screen based on bimolecular fluorescence complementation7, we mapped the proteome of intact ER-PM junctions in living cells without disrupting their architectural integrity. Our approaches lead to the discovery of an ER-resident multi-transmembrane protein that we call STIMATE (STIM-activating enhancer, encoded by TMEM110) as a positive regulator of Ca2+ influx in vertebrates. STIMATE physically interacts with STIM1 to promote STIM1 conformational switch. Genetic depletion of STIMATE substantially reduces STIM1 puncta formation at ER-PM junctions and suppresses the Ca2+-NFAT signaling. Our findings enable further genetic studies to elucidate the function of STIMATE in normal physiology and disease, and set the stage to uncover more uncharted functions of hitherto underexplored ER-PM junctions. PMID:26322679

  3. 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

  4. 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

  5. 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/.

  6. Role of peroxynitrite in the redox regulation of cell signal transduction pathways

    PubMed Central

    Liaudet, Lucas; Vassalli, Giuseppe; Pacher, Pal

    2009-01-01

    Peroxynitrite is a potent oxidant and nitrating species formed from the reaction between the free radicals nitric oxide and superoxide. An excessive formation of peroxynitrite represents an important mechanism contributing to cell death and dysfunction in multiple cardiovascular pathologies, such as myocardial infarction, heart failure and atherosclerosis. Whereas initial works focused on direct oxidative biomolecular damage as the main route of peroxynitrite toxicity, more recent evidence, mainly obtained in vitro, indicates that peroxynitrite also behaves as a potent modulator of various cell signal transduction pathways. Due to its ability to nitrate tyrosine residues, peroxynitrite affects cellular processes dependent on tyrosine phosphorylation. Peroxynitrite also exerts complex effects on the activity of various kinases and phosphatases, resulting in the up- or downregulation of signalling cascades, in a concentration- and cell-dependent manner. Such roles of peroxynitrite in the redox regulation of key signalling pathways for cardiovascular homeostasis, including protein kinase B and C, the MAP kinases, Nuclear Factor Kappa B, as well as signalling dependent on insulin and the sympatho-adrenergic system are presented in detail in this review. PMID:19273391

  7. FAK signalling controls insulin sensitivity through regulation of adipocyte survival

    PubMed Central

    Luk, Cynthia T.; Shi, Sally Yu; Cai, Erica P.; Sivasubramaniyam, Tharini; Krishnamurthy, Mansa; Brunt, Jara J.; Schroer, Stephanie A.; Winer, Daniel A.; Woo, Minna

    2017-01-01

    Focal adhesion kinase (FAK) plays a central role in integrin signalling, which regulates growth and survival of tumours. Here we show that FAK protein levels are increased in adipose tissue of insulin-resistant obese mice and humans. Disruption of adipocyte FAK in mice or in 3T3 L1 cells decreases adipocyte survival. Adipocyte-specific FAK knockout mice display impaired adipose tissue expansion and insulin resistance on prolonged metabolic stress from a high-fat diet or when crossed on an obese db/db or ob/ob genetic background. Treatment of these mice with a PPARγ agonist does not restore adiposity or improve insulin sensitivity. In contrast, inhibition of apoptosis, either genetically or pharmacologically, attenuates adipocyte death, restores normal adiposity and improves insulin sensitivity. Together, these results demonstrate that FAK is required for adipocyte survival and maintenance of insulin sensitivity, particularly in the context of adipose tissue expansion as a result of caloric excess. PMID:28165007

  8. 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

  9. 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

  10. Role of oxytocin signaling in the regulation of body weight.

    PubMed

    Blevins, James E; Ho, Jacqueline M

    2013-12-01

    Obesity and its associated metabolic disorders are growing health concerns in the US and worldwide. In the US alone, more than two-thirds of the adult population is classified as either overweight or obese [1], highlighting the need to develop new, effective treatments for these conditions. Whereas the hormone oxytocin is well known for its peripheral effects on uterine contraction during parturition and milk ejection during lactation, release of oxytocin from somatodendrites and axonal terminals within the central nervous system (CNS) is implicated in both the formation of prosocial behaviors and in the control of energy balance. Recent findings demonstrate that chronic administration of oxytocin reduces food intake and body weight in diet-induced obese (DIO) and genetically obese rodents with impaired or defective leptin signaling. Importantly, chronic systemic administration of oxytocin out to 6 weeks recapitulates the effects of central administration on body weight loss in DIO rodents at doses that do not result in the development of tolerance. Furthermore, these effects are coupled with induction of Fos (a marker of neuronal activation) in hindbrain areas (e.g. dorsal vagal complex (DVC)) linked to the control of meal size and forebrain areas (e.g. hypothalamus, amygdala) linked to the regulation of food intake and body weight. This review assesses the potential central and peripheral targets by which oxytocin may inhibit body weight gain, its regulation by anorexigenic and orexigenic signals, and its potential use as a therapy that can circumvent leptin resistance and reverse the behavioral and metabolic abnormalities associated with DIO and genetically obese models.

  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. 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

  13. Bradyoxetin, a unique chemical signal involved in symbiotic gene regulation

    PubMed Central

    Loh, John; Carlson, Russell W.; York, William S.; Stacey, Gary

    2002-01-01

    Bradyrhizobium japonicum is a symbiotic bacterium that nodulates soybean. Critical for the infection and establishment of this symbiosis are the bacterial nodulation genes (nod, nol, noe), which are induced in the presence of plant produced isoflavones. Transcription of the nodulation genes is also controlled in a population density-dependent fashion. Expression of the nod genes is maximal at low population densities, and decreases significantly at higher culture densities. Population density control of the nodulation genes involves NolA and NodD2, both of which function in tandem to repress nod gene expression. An extracellular secreted factor (CDF) is known to mediate this repression. Here, we report that CDF is a novel signaling molecule, designated bradyoxetin, different from other Gram-negative quorum signals. The proposed structure of bradyoxetin is 2-{4-[[4-(3-aminooxetan-2-yl)phenyl](imino)methyl]phenyl}oxetan-3-ylamine. Interestingly, expression of bradyoxetin is iron-regulated, and is maximally produced under iron-starved conditions. Consistent with this, expression of the nodulation genes occurred in an iron-dependent fashion. Addition of iron to B. japonicum cultures at high optical densities resulted in decreased bradyoxetin production, and a concomitant reduction in nolA expression. A corresponding increase in nodY–lacZ expression was observed with iron treatment. PMID:12393811

  14. Hypothalamic eIF2α Signaling Regulates Food Intake

    PubMed Central

    Maurin, Anne-Catherine; Benani, Alexandre; Lorsignol, Anne; Brenachot, Xavier; Parry, Laurent; Carraro, Valérie; Guissard, Christophe; Averous, Julien; Jousse, Céline; Bruhat, Alain; Chaveroux, Cédric; B’chir, Wafa; Muranishi, Yuki; Ron, David; Pénicaud, Luc; Fafournoux, Pierre

    2016-01-01

    Summary The reversible phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α) is a highly conserved signal implicated in the cellular adaptation to numerous stresses such as the one caused by amino acid limitation. In response to dietary amino acid deficiency, the brain-specific activation of the eIF2α kinase GCN2 leads to food intake inhibition. We report here that GCN2 is rapidly activated in the mediobasal hypothalamus (MBH) after consumption of a leucine-deficient diet. Furthermore, knockdown of GCN2 in this particular area shows that MBH GCN2 activity controls the onset of the aversive response. Importantly, pharmacological experiments demonstrate that the sole phosphorylation of eIF2α in the MBH is sufficient to regulate food intake. eIF2α signaling being at the crossroad of stress pathways activated in several pathological states, our study indicates that hypothalamic eIF2α phosphorylation could play a critical role in the onset of anorexia associated with certain diseases. PMID:24485657

  15. CD147: regulator of hyaluronan signaling in invasiveness and chemoresistance.

    PubMed

    Grass, G Daniel; Dai, Lu; Qin, Zhiqiang; Parsons, Chris; Toole, Bryan P

    2014-01-01

    Major determinants that influence negative outcome in cancer patients are the abilities of cancer cells to resist current therapies and to invade surrounding host tissue, consequently leading to local and metastatic dissemination. Hyaluronan (HA), a prominent constituent of the tumor microenvironment, not only provides structural support but also interacts with cell surface receptors, especially CD44, that influence cooperative signaling pathways leading to chemoresistance and invasiveness. CD147 (emmprin; basigin) is a member of the Ig superfamily that has also been strongly implicated in chemoresistance and invasiveness. CD147 both regulates HA synthesis and interacts with the HA receptors, CD44, and LYVE-1. Increased CD147 expression induces formation of multiprotein complexes containing CD44 (or LYVE-1) as well as members of the membrane-type matrix metalloproteinase, receptor tyrosine kinase, ABC drug transporter, or monocarboxylate transporter families, which become assembled in specialized lipid raft domains along with CD147 itself. In each case, multivalent HA-receptor interactions are essential for formation or stabilization of the lipid raft complexes and for downstream signaling pathways or transporter activities that are driven by these complexes. We conclude that cooperativity between HA, HA receptors, and CD147 may be a major driver of the interconnected pathways of invasiveness and chemoresistance widely critical to malignancy.

  16. 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.

  17. 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

  18. 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.

  19. Neuropeptide Regulation of Signaling and Behavior in the BNST

    PubMed Central

    Kash, Thomas L.; Pleil, Kristen E.; Marcinkiewcz, Catherine A.; Lowery-Gionta, Emily G.; Crowley, Nicole; Mazzone, Christopher; Sugam, Jonathan; Hardaway, J. Andrew; McElligott, Zoe A.

    2015-01-01

    Recent technical developments have transformed how neuroscientists can probe brain function. What was once thought to be difficult and perhaps impossible, stimulating a single set of long range inputs among many, is now relatively straight-forward using optogenetic approaches. This has provided an avalanche of data demonstrating causal roles for circuits in a variety of behaviors. However, despite the critical role that neuropeptide signaling plays in the regulation of behavior and physiology of the brain, there have been remarkably few studies demonstrating how peptide release is causally linked to behaviors. This is likely due to both the different time scale by which peptides act on and the modulatory nature of their actions. For example, while glutamate release can effectively transmit information between synapses in milliseconds, peptide release is potentially slower [See the excellent review by Van Den Pol on the time scales and mechanisms of release (van den Pol, 2012)] and it can only tune the existing signals via modulation. And while there have been some studies exploring mechanisms of release, it is still not as clearly known what is required for efficient peptide release. Furthermore, this analysis could be complicated by the fact that there are multiple peptides released, some of which may act in contrast. Despite these limitations, there are a number of groups making progress in this area. The goal of this review is to explore the role of peptide signaling in one specific structure, the bed nucleus of the stria terminalis, that has proven to be a fertile ground for peptide action. PMID:25475545

  20. 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

  1. From blood oxygenation level dependent (BOLD) signals to brain temperature maps.

    PubMed

    Sotero, Roberto C; Iturria-Medina, Yasser

    2011-11-01

    A theoretical framework is presented for converting Blood Oxygenation Level Dependent (BOLD) images to brain temperature maps, based on the idea that disproportional local changes in cerebral blood flow (CBF) as compared with cerebral metabolic rate of oxygen consumption (CMRO₂) during functional brain activity, lead to both brain temperature changes and the BOLD effect. Using an oxygen limitation model and a BOLD signal model, we obtain a transcendental equation relating CBF and CMRO₂ changes with the corresponding BOLD signal, which is solved in terms of the Lambert W function. Inserting this result in the dynamic bioheat equation describing the rate of temperature changes in the brain, we obtain a nonautonomous ordinary differential equation that depends on the BOLD response, which is solved numerically for each brain voxel. Temperature maps obtained from a real BOLD dataset registered in an attention to visual motion experiment were calculated, obtaining temperature variations in the range: (-0.15, 0.1) which is consistent with experimental results. The statistical analysis revealed that significant temperature activations have a similar distribution pattern than BOLD activations. An interesting difference was the activation of the precuneus in temperature maps, a region involved in visuospatial processing, an effect that was not observed on BOLD maps. Furthermore, temperature maps were more localized to gray matter regions than the original BOLD maps, showing less activated voxels in white matter and cerebrospinal fluid.

  2. 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

  3. 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

  4. Ihh signaling regulates mandibular symphysis development and growth.

    PubMed

    Sugito, H; Shibukawa, Y; Kinumatsu, T; Yasuda, T; Nagayama, M; Yamada, S; Minugh-Purvis, N; Pacifici, M; Koyama, E

    2011-05-01

    Symphyseal secondary cartilage is important for mandibular development, but the molecular mechanisms underlying its formation remain largely unknown. Here we asked whether Indian hedgehog (Ihh) regulates symphyseal cartilage development and growth. By embryonic days 16.5 to 18.5, Sox9-expressing chondrocytes formed within condensed Tgfβ-1/Runx2-expressing mesenchymal cells at the prospective symphyseal joint site, and established a growth-plate-like structure with distinct Ihh, collagen X, and osteopontin expression patterns. In post-natal life, mesenchymal cells expressing the Ihh receptor Patched1 were present anterior to the Ihh-expressing secondary cartilage, proliferated, differentiated into chondrocytes, and contributed to anterior growth of alveolar bone. In Ihh-null mice, however, symphyseal development was defective, mainly because of enhanced chondrocyte maturation and reduced proliferation of chondroprogenitor cells. Proliferation was partially restored in dual Ihh;Gli3 mutants, suggesting that Gli3 is normally a negative regulator of symphyseal development. Thus, Ihh signaling is essential for symphyseal cartilage development and anterior mandibular growth.

  5. Structure, Regulation, Signaling, and Targeting of Abl Kinases in Cancer

    PubMed Central

    2012-01-01

    Abl kinases are prototypic cytoplasmic tyrosine kinases and are involved in a variety of chromosomal aberrations in different cancers. This causes the expression of Abl fusion proteins, such as Bcr-Abl, that are constitutively activated and drivers of tumorigenesis. Over the past decades, biochemical and functional studies on the molecular mechanisms of Abl regulation have gone hand in hand with progression of our structural understanding of autoinhibited and active Abl conformations. In parallel, Abl oncoproteins have become prime molecular targets for cancer therapy, using adenosine triphosphate (ATP)–competitive kinase inhibitors, such as imatinib. Abl-targeting drugs serve as a paradigm for our understanding of kinase inhibitor action, specificity, and resistance development. In this review article, I will review the molecular mechanisms that are responsible for the regulation of Abl kinase activity and how oncogenic Abl fusions signal. Furthermore, past and ongoing efforts to target Abl oncoproteins using ATP-competitive and allosteric inhibitors, as well as future possibilities using combination therapy, will be discussed. PMID:23226581

  6. 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

  7. Moment-to-moment brain signal variability: a next frontier in human brain mapping?

    PubMed

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

    2013-05-01

    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 lifespan 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.

  8. 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.

  9. EGFR/ARF6 regulation of Hh signalling stimulates oncogenic Ras tumour overgrowth.

    PubMed

    Chabu, Chiswili; Li, Da-Ming; Xu, Tian

    2017-03-10

    Multiple signalling events interact in cancer cells. Oncogenic Ras cooperates with Egfr, which cannot be explained by the canonical signalling paradigm. In turn, Egfr cooperates with Hedgehog signalling. How oncogenic Ras elicits and integrates Egfr and Hedgehog signals to drive overgrowth remains unclear. Using a Drosophila tumour model, we show that Egfr cooperates with oncogenic Ras via Arf6, which functions as a novel regulator of Hh signalling. Oncogenic Ras induces the expression of Egfr ligands. Egfr then signals through Arf6, which regulates Hh transport to promote Hh signalling. Blocking any step of this signalling cascade inhibits Hh signalling and correspondingly suppresses the growth of both, fly and human cancer cells harbouring oncogenic Ras mutations. These findings highlight a non-canonical Egfr signalling mechanism, centered on Arf6 as a novel regulator of Hh signalling. This explains both, the puzzling requirement of Egfr in oncogenic Ras-mediated overgrowth and the cooperation between Egfr and Hedgehog.

  10. EGFR/ARF6 regulation of Hh signalling stimulates oncogenic Ras tumour overgrowth

    PubMed Central

    Chabu, Chiswili; Li, Da-Ming; Xu, Tian

    2017-01-01

    Multiple signalling events interact in cancer cells. Oncogenic Ras cooperates with Egfr, which cannot be explained by the canonical signalling paradigm. In turn, Egfr cooperates with Hedgehog signalling. How oncogenic Ras elicits and integrates Egfr and Hedgehog signals to drive overgrowth remains unclear. Using a Drosophila tumour model, we show that Egfr cooperates with oncogenic Ras via Arf6, which functions as a novel regulator of Hh signalling. Oncogenic Ras induces the expression of Egfr ligands. Egfr then signals through Arf6, which regulates Hh transport to promote Hh signalling. Blocking any step of this signalling cascade inhibits Hh signalling and correspondingly suppresses the growth of both, fly and human cancer cells harbouring oncogenic Ras mutations. These findings highlight a non-canonical Egfr signalling mechanism, centered on Arf6 as a novel regulator of Hh signalling. This explains both, the puzzling requirement of Egfr in oncogenic Ras-mediated overgrowth and the cooperation between Egfr and Hedgehog. PMID:28281543

  11. 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

  12. Myostatin signaling regulates Akt activity via the regulation of miR-486 expression.

    PubMed

    Hitachi, Keisuke; Nakatani, Masashi; Tsuchida, Kunihiro

    2014-02-01

    Myostatin, also known as growth and differentiation factor-8, is a pivotal negative regulator of skeletal muscle mass and reduces muscle protein synthesis by inhibiting the insulin-like growth factor-1 (IGF-1)/Akt/mammalian target of rapamycin (mTOR) pathway. However, the precise mechanism by which myostatin inhibits the IGF-1/Akt/mTOR pathway remains unclear. In this study, we investigated the global microRNA expression profile in myostatin knockout mice and identified miR-486, a positive regulator of the IGF-1/Akt pathway, as a novel target of myostatin signaling. In myostatin knockout mice, the expression level of miR-486 in skeletal muscle was significantly increased. In addition, we observed increased expression of the primary transcript of miR-486 (pri-miR-486) and Ankyrin 1.5 (Ank1.5), the host gene of miR-486, in myostatin knockout mice. In C2C12 cells, myostatin negatively regulated the expression of Ank1.5. Moreover, canonical myostatin signaling repressed the skeletal muscle-specific promoter activity of miR-486/Ank1.5. This repression was partially mediated by the E-box elements in the proximal region of the promoter. We also show that overexpression of miR-486 induced myotube hypertrophy in vitro and that miR-486 was essential to maintain skeletal muscle size both in vitro and in vivo. In addition, inhibition of miR-486 led to a decrease in Akt activity in C2C12 myotubes. Our findings indicate that miR-486 is one of the intermediary molecules connecting myostatin signaling and the IGF-1/Akt/mTOR pathway in the regulation of skeletal muscle size.

  13. MicroRNAs: New Regulators of Toll-Like Receptor Signalling Pathways

    PubMed Central

    He, Xiaobing; Jing, Zhizhong; Cheng, Guofeng

    2014-01-01

    Toll-like receptors (TLRs), a critical family of pattern recognition receptors (PRRs), are responsible for the innate immune responses via signalling pathways to provide effective host defence against pathogen infections. However, TLR-signalling pathways are also likely to stringently regulate tissue maintenance and homeostasis by elaborate modulatory mechanisms. MicroRNAs (miRNAs) have emerged as key regulators and as an essential part of the networks involved in regulating TLR-signalling pathways. In this review, we highlight our understanding of the regulation of miRNA expression profiles by TLR-signalling pathways and the regulation of TLR-signalling pathways by miRNAs. We focus on the roles of miRNAs in regulating TLR-signalling pathways by targeting multiple molecules, including TLRs themselves, their associated signalling proteins and regulatory molecules, and transcription factors and functional cytokines induced by them, at multiple levels. PMID:24772440

  14. Signal to noise ratio in water balance maps with different resolution

    NASA Astrophysics Data System (ADS)

    Yan, Ziqi; Gottschalk, Lars; Wang, Jianhua

    2016-12-01

    What is the best resolution of annual water balance maps for a correct balance between the basic spatial signal in the observations of precipitation, actual evapotranspiration and runoff across a larger drainage basin and the error in estimates for grid cells in the map to avoid giving a false impression of accuracy? To answer this question an approach based a signal to noise ratio is proposed, which allows finding the optimal resolution maximizing the signal in the map. The approach is demonstrated on gauge data in the Huai River Basin, China. Stochastic interpolation methods were applied to create grid maps of long-term mean values, as well as for estimating variances of the three water balance components in a range of scales from 5 × 5 km to 200 × 200 km2 grid cells. Interpolation algorithms using covariances of long-term means of data with different spatial support were developed. The identified optimal resolutions by the signal to noise ratio appeared to be very different - 10 × 10, 50 × 50, and 30 × 30 km2 for precipitation, actual evapotranspiration, and runoff, respectively. These values are directly linked to the observation network densities. The magnitude of the signal to noise ratio shows similar strong differences with values 34, 3.7, and 5.4, respectively. It gives a direct indication of the reliability of the map, which can be considered as satisfactory only for precipitation for the data available for the present study. The critical factors for this magnitude are parameters characterising the spatial covariance in data and the network density.

  15. 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.

  16. Conserved Lysine Acetylation within the Microtubule-Binding Domain Regulates MAP2/Tau Family Members

    PubMed Central

    Hwang, Andrew W.; Trzeciakiewicz, Hanna; Friedmann, Dave; Yuan, Chao-Xing; Marmorstein, Ronen; Lee, Virginia M. Y.; Cohen, Todd J.

    2016-01-01

    Lysine acetylation has emerged as a dominant post-translational modification (PTM) regulating tau proteins in Alzheimer’s disease (AD) and related tauopathies. Mass spectrometry studies indicate that tau acetylation sites cluster within the microtubule-binding region (MTBR), a region that is highly conserved among tau, MAP2, and MAP4 family members, implying that acetylation could represent a conserved regulatory mechanism for MAPs beyond tau. Here, we combined mass spectrometry, biochemical assays, and cell-based approaches to demonstrate that the tau family members MAP2 and MAP4 are also subject to reversible acetylation. We identify a cluster of lysines in the MAP2 and MAP4 MTBR that undergo CBP-catalyzed acetylation, many of which are conserved in tau. Similar to tau, MAP2 acetylation can occur in a cysteine-dependent auto-regulatory manner in the presence of acetyl-CoA. Furthermore, tubulin reduced MAP2 acetylation, suggesting tubulin binding dictates MAP acetylation status. Taken together, these results uncover a striking conservation of MAP2/Tau family post-translational modifications that could expand our understanding of the dynamic mechanisms regulating microtubules. PMID:28002468

  17. 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.

  18. Regulation of longevity by regulator of G-protein signaling protein, Loco.

    PubMed

    Lin, Yuh-Ru; Kim, Keetae; Yang, Yanfei; Ivessa, Andreas; Sadoshima, Junichi; Park, Yongkyu

    2011-06-01

    Regulator of G-protein signaling (RGS) proteins contribute to G-protein signaling pathways as activators or repressors with GTPase-activating protein (GAP) activity. To characterize whether regulation of RGS proteins influences longevity in several species, we measured stress responses and lifespan of RGS-overexpressing and RGS-lacking mutants. Reduced expression of Loco, a RGS protein of Drosophila melanogaster, resulted in a longer lifespan for both male and female flies, also exhibiting stronger resistance to three different stressors (starvation, oxidation, and heat) and higher manganese-containing superoxide dismutase (MnSOD) activity. In addition, this reduction in Loco expression increased fat content and diminished cAMP levels. In contrast, overexpression of both genomic and cDNA loco gene significantly shortened the lifespan with weaker stress resistance and lower fat content. Deletion analysis of the Loco demonstrated that its RGS domain is required for the regulation of longevity. Consistently, when expression of RGS14, mammalian homologue of Loco, was reduced in rat fibroblast cells, the resistance to oxidative stress increased with higher MnSOD expression. The changes of yeast Rgs2 expression, which shares a conserved RGS domain with the fly Loco protein, also altered lifespan and stress resistance in Saccharomyces cerevisiae. Here, we provide the first evidence that RGS proteins with GAP activity affect both stress resistance and longevity in several species.

  19. 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…

  20. A Signaling-Regulated, Short-Chain Dehydrogenase of Stagonospora nodorum Regulates Asexual Development ▿ ‡

    PubMed Central

    Tan, Kar-Chun; Heazlewood, Joshua L.; Millar, A. Harvey; Thomson, Gordon; Oliver, Richard P.; Solomon, Peter S.

    2008-01-01

    The fungus Stagonospora nodorum is a causal agent of leaf and glume blotch disease of wheat. It has been previously shown that inactivation of heterotrimeric G protein signaling in Stagonospora nodorum caused development defects and reduced pathogenicity [P. S. Solomon et al., Mol. Plant-Microbe Interact. 17:456-466, 2004]. In this study, we sought to identify targets of the signaling pathway that may have contributed to phenotypic defects of the signaling mutants. A comparative analysis of Stagonospora nodorum wild-type and Gα-defective mutant (gna1) intracellular proteomes was performed via two-dimensional polyacrylamide gel electrophoresis. Several proteins showed significantly altered abundances when comparing the two strains. One such protein, the short-chain dehydrogenase Sch1, was 18-fold less abundant in the gna1 strain, implying that it is positively regulated by Gα signaling. Gene expression and transcriptional enhanced green fluorescent protein fusion analyses of Sch1 indicates strong expression during asexual development. Mutant strains of Stagonospora nodorum lacking Sch1 demonstrated poor growth on minimal media and exhibited a significant reduction in asexual sporulation on all growth media examined. Detailed histological experiments on sch1 pycnidia revealed that the gene is required for the differentiation of the subparietal layers of asexual pycnidia resulting in a significant reduction in both pycnidiospore size and numbers. PMID:18776038

  1. Regulation of the wheat MAP kinase phosphatase 1 by 14-3-3 proteins.

    PubMed

    Ghorbel, Mouna; Cotelle, Valérie; Ebel, Chantal; Zaidi, Ikram; Ormancey, Mélanie; Galaud, Jean-Philippe; Hanin, Moez

    2017-04-01

    Plant MAP kinase phosphatases (MKPs) are major regulators of MAPK signaling pathways and play crucial roles in controlling growth, development and stress responses. The presence of several functional domains in plant MKPs such as a dual specificity phosphatase catalytic domain, gelsolin, calmodulin-binding and serine-rich domains, suggests that MKPs can interact with distinct cellular partners, others than MAPKs. In this report, we identified a canonical mode I 14-3-3-binding motif (574KLPSLP579) located at the carboxy-terminal region of the wheat MKP, TMKP1. We found that this motif is well-conserved among other MKPs from monocots including Hordeum vulgare, Brachypodium distachyon and Aegilops taushii. Using co-immunoprecipitation assays, we provide evidence for interaction between TMKP1 and 14-3-3 proteins in wheat. Moreover, the phosphatase activity of TMKP1 is increased in a phospho-dependent manner by either Arabidopsis or yeast 14-3-3 isoforms. TMKP1 activation by 14-3-3 proteins is enhanced by Mn(2+), whereas in the presence of Ca(2+) ions, TMKP1 activation was limited to Arabidopsis 14-3-3φ (phi), an isoform harboring an EF-hand motif. Such findings strongly suggest that 14-3-3 proteins, in conjunction with specific divalent cations, may stimulate TMKP1 activity and point-out that 14-3-3 proteins bind and regulate the activity of a MKP in eukaryotes.

  2. Regulation of PKC Mediated Signaling by Calcium during Visceral Leishmaniasis

    PubMed Central

    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

  3. AKAP signaling complexes in regulation of excitatory synaptic plasticity.

    PubMed

    Sanderson, Jennifer L; Dell'Acqua, Mark L

    2011-06-01

    Plasticity at excitatory glutamatergic synapses in the central nervous system is believed to be critical for neuronal circuits to process and encode information, allowing animals to perform complex behaviors such as learning and memory. In addition, alterations in synaptic plasticity are associated with human diseases, including Alzheimer disease, epilepsy, chronic pain, drug addiction, and schizophrenia. Long-term potentiation (LTP) and depression (LTD) in the hippocampal region of the brain are two forms of synaptic plasticity that increase or decrease, respectively, the strength of synaptic transmission by postsynaptic AMPA-type glutamate receptors. Both LTP and LTD are induced by activation of NMDA-type glutamate receptors but differ in the level and duration of Ca(2+) influx through the NMDA receptor and the subsequent engagement of downstream signaling by protein kinases, including PKA, PKC, and CaMKII, and phosphatases, including PP1 and calcineurin-PP2B (CaN). This review addresses the important emerging roles of the A-kinase anchoring protein family of scaffold proteins in regulating localization of PKA and other kinases and phosphatases to postsynaptic multiprotein complexes that control NMDA and AMPA receptor function during LTP and LTD.

  4. AKAP Signaling Complexes in Regulation of Excitatory Synaptic Plasticity

    PubMed Central

    Sanderson, Jennifer L.; Dell'Acqua, Mark L.

    2011-01-01

    Plasticity at excitatory glutamatergic synapses in the central nervous system is believed to be critical for neuronal circuits to process and encode information allowing animals to perform complex behaviors such as learning and memory. In addition, alterations in synaptic plasticity are associated with human diseases including Alzheimer's, epilepsy, chronic pain, drug addiction, and schizophrenia. Long-term potentiation (LTP) and depression (LTD) in the hippocampal region of the brain are two forms of synaptic plasticity that increase or decrease, respectively, the strength of synaptic transmission by postsynaptic AMPA-type glutamate receptors. Both LTP and LTD are induced by activation of NMDA-type glutamate receptors but differ in the level and duration of Ca2+ influx through the NMDA receptor and the subsequent engagement of downstream signaling by protein kinases including PKA, PKC, and CaMKII and phosphatases including PP1 and calcineurin-PP2B (CaN). This review addresses the important emerging roles of the A-kinase anchoring protein (AKAP) family of scaffold proteins in regulating localization of PKA and other kinases and phosphatases to postsynaptic multi-protein complexes that control NMDA and AMPA receptor function during LTP and LTD. PMID:21498812

  5. 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

  6. Feedback control of AHR signalling regulates intestinal immunity.

    PubMed

    Schiering, Chris; Wincent, Emma; Metidji, Amina; Iseppon, Andrea; Li, Ying; Potocnik, Alexandre J; Omenetti, Sara; Henderson, Colin J; Wolf, C Roland; Nebert, Daniel W; Stockinger, Brigitta

    2017-02-09

    The aryl hydrocarbon receptor (AHR) recognizes xenobiotics as well as natural compounds such as tryptophan metabolites, dietary components and microbiota-derived factors, and it is important for maintenance of homeostasis at mucosal surfaces. AHR activation induces cytochrome P4501 (CYP1) enzymes, which oxygenate AHR ligands, leading to their metabolic clearance and detoxification. Thus, CYP1 enzymes have an important feedback role that curtails the duration of AHR signalling, but it remains unclear whether they also regulate AHR ligand availability in vivo. Here we show that dysregulated expression of Cyp1a1 in mice depletes the reservoir of natural AHR ligands, generating a quasi AHR-deficient state. Constitutive expression of Cyp1a1 throughout the body or restricted specifically to intestinal epithelial cells resulted in loss of AHR-dependent type 3 innate lymphoid cells and T helper 17 cells and increased susceptibility to enteric infection. The deleterious effects of excessive AHR ligand degradation on intestinal immune functions could be counter-balanced by increasing the intake of AHR ligands in the diet. Thus, our data indicate that intestinal epithelial cells serve as gatekeepers for the supply of AHR ligands to the host and emphasize the importance of feedback control in modulating AHR pathway activation.

  7. 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

  8. 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

  9. Regulator of G protein signaling proteins differentially modulate signaling of μ and δ opioid receptors

    PubMed Central

    Xie, Zhihua; Li, Zhisong; Guo, Lei; Ye, Caiying; Li, Juan; Yu, Xiaoli; Yang, Huifen; Wang, Yulin; Chen, Chongguang; Zhang, Dechang; Liu-Chen, Lee-Yuan

    2009-01-01

    Effects of regulator of G protein signaling (RGS) proteins on μ and δ opioid receptors were investigated in HEK293 cells. Co-expression of RGS1, RGS2, RGS4, RGS9, RGS10 or RGS19 (Gα-interacting protein (GAIP)) significantly reduced [Tyr-D-Ala-Gly-N-methyl-Phe-Gly-ol]-Enkephalin (DAMGO)-induced inhibition of adenylyl cyclase (AC) mediated by μ opioid receptor, but only RGS9 decreased the effects of [Tyr-D-Pen-Gly-p-Chloro-Phe-D-Pen]-Enkephalin (DPDPE) mediated by δ opioid receptor. When C-tails of the receptors were exchanged (μ/δC and δ/μC chimeras), RGS proteins decreased δ/μC-mediated AC inhibition, but none had significant effects on that via μ/δC receptor. Thus, the C-terminal domains of the receptors are critical for the differential effects of RGS proteins, which may be due to differences in receptor - G protein - RGS protein interactions in signaling complexes. PMID:17433292

  10. Systematic interactome mapping and genetic perturbation analysis of a C. elegans TGF-beta signaling network.

    PubMed

    Tewari, Muneesh; Hu, Patrick J; Ahn, Jin Sook; Ayivi-Guedehoussou, Nono; Vidalain, Pierre-Olivier; Li, Siming; Milstein, Stuart; Armstrong, Chris M; Boxem, Mike; Butler, Maurice D; Busiguina, Svetlana; Rual, Jean-François; Ibarrola, Nieves; Chaklos, Sabrina T; Bertin, Nicolas; Vaglio, Philippe; Edgley, Mark L; King, Kevin V; Albert, Patrice S; Vandenhaute, Jean; Pandey, Akhilesh; Riddle, Donald L; Ruvkun, Gary; Vidal, Marc

    2004-02-27

    To initiate a system-level analysis of C. elegans DAF-7/TGF-beta signaling, we combined interactome mapping with single and double genetic perturbations. Yeast two-hybrid (Y2H) screens starting with known DAF-7/TGF-beta pathway components defined a network of 71 interactions among 59 proteins. Coaffinity purification (co-AP) assays in mammalian cells confirmed the overall quality of this network. Systematic perturbations of the network using RNAi, both in wild-type and daf-7/TGF-beta pathway mutant animals, identified nine DAF-7/TGF-beta signaling modifiers, seven of which are conserved in humans. We show that one of these has functional homology to human SNO/SKI oncoproteins and that mutations at the corresponding genetic locus daf-5 confer defects in DAF-7/TGF-beta signaling. Our results reveal substantial molecular complexity in DAF-7/TGF-beta signal transduction. Integrating interactome maps with systematic genetic perturbations may be useful for developing a systems biology approach to this and other signaling modules.

  11. A signal processing view of strip-mapping synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Munson, David C., Jr.; Visentin, Robert L.

    1989-01-01

    The authors derive the fundamental strip-mapping SAR (synthetic aperture radar) imaging equations from first principles. They show that the resolution mechanism relies on the geometry of the imaging situation rather than on the Doppler effect. Both the airborne and spaceborne cases are considered. Range processing is discussed by presenting an analysis of pulse compression and formulating a mathematical model of the radar return signal. This formulation is used to obtain the airborne SAR model. The authors study the resolution mechanism and derive the signal processing relations needed to produce a high-resolution image. They introduce spotlight-mode SAR and briefly indicate how polar-format spotlight processing can be used in strip-mapping SAR. They discuss a number of current and future research directions in SAR imaging.

  12. 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

  13. The Arabidopsis microtubule-associated protein MAP65-3 supports infection by filamentous biotrophic pathogens by down-regulating salicylic acid-dependent defenses.

    PubMed

    Quentin, Michaël; Baurès, Isabelle; Hoefle, Caroline; Caillaud, Marie-Cécile; Allasia, Valérie; Panabières, Franck; Abad, Pierre; Hückelhoven, Ralph; Keller, Harald; Favery, Bruno

    2016-03-01

    The oomycete Hyaloperonospora arabidopsidis and the ascomycete Erysiphe cruciferarum are obligate biotrophic pathogens causing downy mildew and powdery mildew, respectively, on Arabidopsis. Upon infection, the filamentous pathogens induce the formation of intracellular bulbous structures called haustoria, which are required for the biotrophic lifestyle. We previously showed that the microtubule-associated protein AtMAP65-3 plays a critical role in organizing cytoskeleton microtubule arrays during mitosis and cytokinesis. This renders the protein essential for the development of giant cells, which are the feeding sites induced by root knot nematodes. Here, we show that AtMAP65-3 expression is also induced in leaves upon infection by the downy mildew oomycete and the powdery mildew fungus. Loss of AtMAP65-3 function in the map65-3 mutant dramatically reduced infection by both pathogens, predominantly at the stages of leaf penetration. Whole-transcriptome analysis showed an over-represented, constitutive activation of genes involved in salicylic acid (SA) biosynthesis, signaling, and defense execution in map65-3, whereas jasmonic acid (JA)-mediated signaling was down-regulated. Preventing SA synthesis and accumulation in map65-3 rescued plant susceptibility to pathogens, but not the developmental phenotype caused by cytoskeleton defaults. AtMAP65-3 thus has a dual role. It positively regulates cytokinesis, thus plant growth and development, and negatively interferes with plant defense against filamentous biotrophs. Our data suggest that downy mildew and powdery mildew stimulate AtMAP65-3 expression to down-regulate SA signaling for infection.

  14. Chemical Genetics Approach Reveals Importance of cAMP and MAP Kinase Signaling to Lipid and Carotenoid Biosynthesis in Microalgae.

    PubMed

    Choi, Yoon-E; Rhee, Jin-Kyu; Kim, Hyun-Soo; Ahn, Joon-Woo; Hwang, Hyemin; Yang, Ji-Won

    2015-05-01

    In this study, we attempted to understand signaling pathways behind lipid biosynthesis by employing a chemical genetics approach based on small molecule inhibitors. Specific signaling inhibitors of MAP kinase or modulators of cAMP signaling were selected to evaluate the functional roles of each of the key signaling pathways in three different microalgal species: Chlamydomonas reinhardtii, Chlorella vulgaris, and Haematococcus pluvialis. Our results clearly indicate that cAMP signaling pathways are indeed positively associated with microalgal lipid biosynthesis. In contrast, MAP kinase pathways in three microalgal species are all negatively implicated in both lipid and carotenoid biosynthesis.

  15. Phosphorylation of the TAL1 oncoprotein by the extracellular-signal-regulated protein kinase ERK1.

    PubMed Central

    Cheng, J T; Cobb, M H; Baer, R

    1993-01-01

    Alteration of the TAL1 gene is the most common genetic lesion found in T-cell acute lymphoblastic leukemia. TAL1 encodes phosphoproteins, pp42TAL1 and pp22TAL1, that represent phosphorylated versions of the full-length (residues 1 to 331) and truncated (residues 176 to 331) TAL1 gene products, respectively. Both proteins contain the basic helix-loop-helix motif, a DNA-binding and protein dimerization motif common to several known transcriptional regulatory factors. We now report that serine residue 122 (S122) is a major phosphorylation site of pp42TAL1 in leukemic cell lines and transfected COS1 cells. In vivo phosphorylation of S122 is induced by epidermal growth factor with a rapid time course that parallels activation of the ERK/MAP2 protein kinases. Moreover, S122 is readily phosphorylated in vitro by the extracellular signal-regulated protein kinase ERK1. These data suggest that TAL1 residue S122 serves as an in vivo substrate for ERK/MAP2 kinases such as ERK1. Therefore, S122 phosphorylation may provide a mechanism whereby the properties of TAL1 polypeptides can be modulated by extracellular stimuli. Images PMID:8423803

  16. 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.

  17. 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.

  18. Complex regulation of HSC emergence by the Notch signaling pathway

    PubMed Central

    Butko, Emerald; Pouget, Claire; Traver, David

    2016-01-01

    Hematopoietic stem cells are formed during embryonic development, and serve as the foundation of the definitive blood program for life. Notch signaling has been well established as an essential direct contributor to HSC specification. However, several recent studies have indicated that the contribution of Notch signaling is complex. HSC specification requires multiple Notch signaling inputs, some received directly by hematopoietic precursors, and others that occur indirectly within neighboring somites. Of note, proinflammatory signals provided by primitive myeloid cells are needed for HSC specification via upregulation of the Notch pathway in hemogenic endothelium. In addition to multiple requirements for Notch activation, recent studies indicate that Notch signaling must subsequently be repressed to permit HSC emergence. Finally, Notch must then be reactivated to maintain HSC fate. In this review, we discuss the growing understanding of the dynamic contributions of Notch signaling to the establishment of hematopoiesis during development. PMID:26586199

  19. Plastids Are Major Regulators of Light Signaling in Arabidopsis1[W][OA

    PubMed Central

    Ruckle, Michael E.; Burgoon, Lyle D.; Lawrence, Lauren A.; Sinkler, Christopher A.; Larkin, Robert M.

    2012-01-01

    We previously provided evidence that plastid signaling regulates the downstream components of a light signaling network and that this signal integration coordinates chloroplast biogenesis with both the light environment and development by regulating gene expression. We tested these ideas by analyzing light- and plastid-regulated transcriptomes in Arabidopsis (Arabidopsis thaliana). We found that the enrichment of Gene Ontology terms in these transcriptomes is consistent with the integration of light and plastid signaling (1) down-regulating photosynthesis and inducing both repair and stress tolerance in dysfunctional chloroplasts and (2) helping coordinate processes such as growth, the circadian rhythm, and stress responses with the degree of chloroplast function. We then tested whether factors that contribute to this signal integration are also regulated by light and plastid signals by characterizing T-DNA insertion alleles of genes that are regulated by light and plastid signaling and that encode proteins that are annotated as contributing to signaling, transcription, or no known function. We found that a high proportion of these mutant alleles induce chloroplast biogenesis during deetiolation. We quantified the expression of four photosynthesis-related genes in seven of these enhanced deetiolation (end) mutants and found that photosynthesis-related gene expression is attenuated. This attenuation is particularly striking for Photosystem II subunit S expression. We conclude that the integration of light and plastid signaling regulates a number of END genes that help optimize chloroplast function and that at least some END genes affect photosynthesis-related gene expression. PMID:22383539

  20. 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 ...

  1. 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...

  2. Signalling of abscisic acid to regulate plant growth.

    PubMed Central

    Himmelbach, A; Iten, M; Grill, E

    1998-01-01

    Abscisic acid (ABA) mediated growth control is a fundamental response of plants to adverse environmental cues. The linkage between ABA perception and growth control is currently being unravelled by using different experimental approaches such as mutant analysis and microinjection experiments. So far, two protein phosphatases, ABI1 and ABI2, cADPR, pH, and Ca2+ have been identified as main components of the ABA signalling pathway. Here, the ABA signal transduction pathway is compared to signalling cascades from yeast and mammalian cells. A model for a bifurcated ABA signal transduction pathway exerting a positive and negative control mechanism is proposed. PMID:9800207

  3. Signal-to-noise analysis of cerebral blood volume maps from dynamic NMR imaging studies.

    PubMed

    Boxerman, J L; Rosen, B R; Weisskoff, R M

    1997-01-01

    The use of cerebral blood volume (CBV) maps generated from dynamic MRI studies tracking the bolus passage of paramagnetic contrast agents strongly depends on the signal-to-noise ratio (SNR) of the maps. The authors present a semianalytic model for the noise in CBV maps and introduce analytic and Monte Carlo techniques for determining the effect of experimental parameters and processing strategies upon CBV-SNR. CBV-SNR increases as more points are used to estimate the baseline signal level. For typical injections, maps made with 10 baseline points have 34% more noise than those made with 50 baseline points. For a given peak percentage signal drop, an optimum TE can be chosen that, in general, is less than the baseline T2. However, because CBV-SNR is relatively insensitive to TE around this optimum value, choosing TE approximately equal to T2 does not sacrifice much SNR for typical doses of contrast agent. The TR that maximizes spin-echo CBV-SNR satisfies TR/T1 approximately equal to 1.26, whereas as short a TR as possible should be used to maximize gradient-echo CBV-SNR. In general, CBV-SNR is maximized for a given dose of contrast agent by selecting as short an input bolus duration as possible. For image SNR exceeding 20-30, the gamma-fitting procedure adds little extra noise compared with simple numeric integration. However, for noisier input images, can be the case for high resolution echo-planar images, the covarying parameters of the gamma-variate fit broaden the distribution of the CBV estimate and thereby decrease CBV-SNR. The authors compared the analytic noise predicted by their model with that of actual patient data and found that the analytic model accounts for roughly 70% of the measured variability of CBV within white matter regions of interest.

  4. Pea3 expression is regulated by FGF signaling in developing retina

    PubMed Central

    McCabe, Kathryn Leigh; McGuire, Chris; Reh, Thomas A.

    2008-01-01

    FGF signaling has been implicated as an important regulator of retinal development. As a first step in characterizing potential downstream targets of FGF signaling in the retina, we have analyzed expression of Pea3, a member of the Pea3 class of Ets-domain transcription factors, in the developing eye. We find that Pea3 is expressed in the developing retina, and its transcription is regulated by FGF receptor activation. In addition, FGF signaling activates Cath5, a gene necessary for retinal ganglion cell differentiation. These results suggest that FGF signaling via MAPK up-regulates transcription factors that in turn control retinal ganglion cell differentiation. PMID:16273524

  5. 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.

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

    PubMed

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

    2015-02-15

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

  7. 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

  8. MAP65-1a positively regulates H2O2 amplification and enhances brassinosteroid-induced antioxidant defence in maize.

    PubMed

    Zhu, Yuan; Zuo, Mingxing; Liang, Yali; Jiang, Mingyi; Zhang, Jianhua; Scheller, Henrik Vibe; Tan, Mingpu; Zhang, Aying

    2013-09-01

    Brassinosteroid (BR)-induced antioxidant defence has been shown to enhance stress tolerance. In this study, the role of the maize 65 kDa microtubule-associated protein (MAP65), ZmMAP65-1a, in BR-induced antioxidant defence was investigated. Treatment with BR increased the expression of ZmMAP65-1a in maize (Zea mays) leaves and mesophyll protoplasts. Transient expression and RNA interference silencing of ZmMAP65-1a in mesophyll protoplasts further revealed that ZmMAP65-1a is required for the BR-induced increase in expression and activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX). Both exogenous and BR-induced endogenous H2O2 increased the expression of ZmMAP65-1a. Conversely, transient expression of ZmMAP65-1a in maize mesophyll protoplasts enhanced BR-induced H2O2 accumulation, while transient silencing of ZmMAP65-1a blocked the BR-induced expression of NADPH oxidase genes and inhibited BR-induced H2O2 accumulation. Inhibiting the activity and gene expression of ZmMPK5 significantly prevented the BR-induced expression of ZmMAP65-1a. Likewise, transient expression of ZmMPK5 enhanced BR-induced activities of the antioxidant defence enzymes SOD and APX in a ZmMAP65- 1a-dependent manner. ZmMPK5 directly interacted with ZmMAP65-1a in vivo and phosphorylated ZmMAP65-1a in vitro. These results suggest that BR-induced antioxidant defence in maize operates through the interaction of ZmMPK5 with ZmMAP65-1a. Furthermore, ZmMAP65-1a functions in H2O2 self-propagation via regulation of the expression of NADPH oxidase genes in BR signalling.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. Cardiac Fibroblast-Specific Activating Transcription Factor 3 Protects Against Heart Failure by Suppressing MAP2K3-p38 Signaling.

    PubMed

    Li, Yulin; Li, Zhenya; Zhang, Congcong; Li, Ping; Wu, Yina; Wang, Chunxiao; Lau, Wayne Bond; Ma, Xin-Liang; Du, Jie

    2017-03-01

    Background -Hypertensive ventricular remodeling is a common cause of heart failure. However, the molecular mechanisms regulating ventricular remodeling remain poorly understood. Methods -We used a discovery-driven/nonbiased approach to indentify increased ATF3 expression in hypertensive heart. We employed loss/gain of function approaches to understand the role of ATF3 in heart failure. We also examine the mechanisms through transcriptome, CHIP-seq analysis and in vivo and vitro experiments. Results -ATF3 expression increased in murine hypertensive heart and human hypertrophic heart. Cardiac fibroblast cells are the primary cell type expressing high ATF3 levels in response to hypertensive stimuli. ATF3 knockout (ATF3KO) markedly exaggerated hypertensive ventricular remodeling, a state rescued by lentivirus-mediated/miRNA-aided cardiac fibroblast-selective ATF3 overexpression. Conversely, conditional cardiac fibroblast cell-specific ATF3 transgenic overexpression significantly ameliorated ventricular remodeling and heart failure. We identified Map2K3 as a novel ATF3 target. ATF3 binds with the Map2K3 promoter, recruiting HDAC1, resulting in Map2K3 gene-associated histone deacetylation, thereby inhibiting Map2K3 expression. Genetic Map2K3 knockdown rescued the pro-fibrotic/hypertrophic phenotype in ATF3KO cells. Finally, we demonstrated that p38 is the downstream molecule of Map2K3 mediating the pro-fibrotic/hypertrophic effects in ATF3KO animals. Inhibition of p38 signaling reduced TGF-β signaling-related pro-fibrotic and hypertrophic gene expression, and blocked exaggerated cardiac remodeling in ATF3KO cells. Conclusions -Our study provides the first evidence that ATF3 upregulation in cardiac fibroblasts in response to hypertensive stimuli protects heart by suppressing Map2K3 expression and subsequent p38-TGF-β signaling. These results suggest that positive modulation of cardiac fibroblast ATF3 may represent a novel therapeutic approach against hypertensive

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

    PubMed

    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

    2016-07-28

    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.

  15. 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

  16. Regulation of Transcriptional Bursting by a Naturally Oscillating Signal

    PubMed Central

    Corrigan, Adam M.; Chubb, Jonathan R.

    2014-01-01

    Summary Transcription is highly stochastic, occurring in irregular bursts [1–3]. For temporal and spatial precision of gene expression, cells must somehow deal with this noisy behavior. To address how this is achieved, we investigated how transcriptional bursting is entrained by a naturally oscillating signal, by direct measurement of transcription together with signal dynamics in living cells. We identify a Dictyostelium gene showing rapid transcriptional oscillations with the same period as extracellular cAMP signaling waves. Bursting approaches antiphase to cAMP waves, with accelerating transcription cycles during differentiation. Although coupling between signal and transcription oscillations was clear at the population level, single-cell transcriptional bursts retained considerable heterogeneity, indicating that transcription is not governed solely by signaling frequency. Previous studies implied that burst heterogeneity reflects distinct chromatin states [4–6]. Here we show that heterogeneity is determined by multiple intrinsic and extrinsic cues and is maintained by a transcriptional persistence. Unusually for a persistent transcriptional behavior, the lifetime was only 20 min, with rapid randomization of transcriptional state by the response to oscillatory signaling. Linking transcription to rapid signaling oscillations allows reduction of gene expression heterogeneity by temporal averaging, providing a mechanism to generate precision in cell choices during development. PMID:24388853

  17. 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

  18. Mapping the signal-to-noise-ratios of cortical sources in magnetoencephalography and electroencephalography.

    PubMed

    Goldenholz, Daniel M; Ahlfors, Seppo P; Hämäläinen, Matti S; Sharon, Dahlia; Ishitobi, Mamiko; Vaina, Lucia M; Stufflebeam, Steven M

    2009-04-01

    Although magnetoencephalography (MEG) and electroencephalography (EEG) have been available for decades, their relative merits are still debated. We examined regional differences in signal-to-noise-ratios (SNRs) of cortical sources in MEG and EEG. Data from four subjects were used to simulate focal and extended sources located on the cortical surface reconstructed from high-resolution magnetic resonance images. The SNR maps for MEG and EEG were found to be complementary. The SNR of deep sources was larger in EEG than in MEG, whereas the opposite was typically the case for superficial sources. Overall, the SNR maps were more uniform for EEG than for MEG. When using a noise model based on uniformly distributed random sources on the cortex, the SNR in MEG was found to be underestimated, compared with the maps obtained with noise estimated from actual recorded MEG and EEG data. With extended sources, the total area of cortex in which the SNR was higher in EEG than in MEG was larger than with focal sources. Clinically, SNR maps in a patient explained differential sensitivity of MEG and EEG in detecting epileptic activity. Our results emphasize the benefits of recording MEG and EEG simultaneously.

  19. Mapping the Signal-To-Noise-Ratios of Cortical Sources in Magnetoencephalography and Electroencephalography

    PubMed Central

    Goldenholz, Daniel M.; Ahlfors, Seppo P.; Hämäläinen, Matti S.; Sharon, Dahlia; Ishitobi, Mamiko; Vaina, Lucia M.; Stufflebeam, Steven M.

    2010-01-01

    Although magnetoencephalography (MEG) and electroencephalography (EEG) have been available for decades, their relative merits are still debated. We examined regional differences in signal-to-noise-ratios (SNRs) of cortical sources in MEG and EEG. Data from four subjects were used to simulate focal and extended sources located on the cortical surface reconstructed from high-resolution magnetic resonance images. The SNR maps for MEG and EEG were found to be complementary. The SNR of deep sources was larger in EEG than in MEG, whereas the opposite was typically the case for superficial sources. Overall, the SNR maps were more uniform for EEG than for MEG. When using a noise model based on uniformly distributed random sources on the cortex, the SNR in MEG was found to be underestimated, compared with the maps obtained with noise estimated from actual recorded MEG and EEG data. With extended sources, the total area of cortex in which the SNR was higher in EEG than in MEG was larger than with focal sources. Clinically, SNR maps in a patient explained differential sensitivity of MEG and EEG in detecting epileptic activity. Our results emphasize the benefits of recording MEG and EEG simultaneously. PMID:18465745

  20. Comprehensive gene expression atlas for the Arabidopsis MAP kinase signalling pathways.

    PubMed

    Menges, Margit; Dóczi, Róbert; Okrész, László; Morandini, Piero; Mizzi, Luca; Soloviev, Mikhail; Murray, James A H; Bögre, László

    2008-01-01

    * Mitogen activated protein kinase (MAPK) pathways are signal transduction modules with layers of protein kinases having c. 120 genes in Arabidopsis, but only a few have been linked experimentally to functions. * We analysed microarray expression data for 114 MAPK signalling genes represented on the ATH1 Affymetrix arrays; determined their expression patterns during development, and in a wide range of time-course microarray experiments for their signal-dependent transcriptional regulation and their coregulation with other signalling components and transcription factors. * Global expression correlation of the MAPK genes with each of the represented 21 692 Arabidopsis genes was determined by calculating Pearson correlation coefficients. To group MAPK signalling genes based on similarities in global regulation, we performed hierarchical clustering on the pairwise correlation values. This should allow inferring functional information from well-studied MAPK components to functionally uncharacterized ones. Statistical overrepresentation of specific gene ontology (GO) categories in the gene lists showing high expression correlation values with each of the MAPK components predicted biological themes for the gene functions. * The combination of these methods provides functional information for many uncharacterized MAPK genes, and a framework for complementary future experimental dissection of the function of this complex family.

  1. Conserved insulin signaling in the regulation of oocyte growth, development, and maturation.

    PubMed

    Das, Debabrata; Arur, Swathi

    2017-04-05

    Insulin signaling regulates various aspects of physiology, such as glucose homeostasis and aging, and is a key determinant of female reproduction in metazoans. That insulin signaling is crucial for female reproductive health is clear from clinical data linking hyperinsulinemic and hypoinsulinemic condition with certain types of ovarian dysfunction, such as altered steroidogenesis, polycystic ovary syndrome, and infertility. Thus, understanding the signaling mechanisms that underlie the control of insulin-mediated ovarian development is important for the accurate diagnosis of and intervention for female infertility. Studies of invertebrate and vertebrate model systems have revealed the molecular determinants that transduce insulin signaling as well as which biological processes are regulated by the insulin-signaling pathway. The molecular determinants of the insulin-signaling pathway, from the insulin receptor to its downstream signaling components, are structurally and functionally conserved across evolution, from worms to mammals - yet, physiological differences in signaling still exist. Insulin signaling acts cooperatively with gonadotropins in mammals and lower vertebrates to mediate various aspects of ovarian development, mainly owing to evolution of the endocrine system in vertebrates. In contrast, insulin signaling in Drosophila and Caenorhabditis elegans directly regulates oocyte growth and maturation. In this review, we compare and contrast insulin-mediated regulation of ovarian functions in mammals, lower vertebrates, C. elegans, and Drosophila, and highlight conserved signaling pathways and regulatory mechanisms in general while illustrating insulin's unique role in specific reproductive processes. This article is protected by copyright. All rights reserved.

  2. 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.

  3. 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.

  4. IκB Kinase 2 Regulates TPL-2 Activation of Extracellular Signal-Regulated Kinases 1 and 2 by Direct Phosphorylation of TPL-2 Serine 400

    PubMed Central

    Roget, Karine; Ben-Addi, Abduelhakem; Mambole-Dema, Agnes; Gantke, Thorsten; Yang, Huei-Ting; Janzen, Julia; Morrice, Nick; Abbott, Derek

    2012-01-01

    Tumor progression locus 2 (TPL-2) functions as a MEK-1/2 kinase, which is essential for Toll-like receptor 4 (TLR4) activation of extracellular signal-regulated kinase 1 and 2 (ERK-1/2) mitogen-activated protein (MAP) kinases in lipopolysaccharide (LPS)-stimulated macrophages and for inducing the production of the proinflammatory cytokines tumor necrosis factor and interleukin-1β. In unstimulated cells, association of TPL-2 with NF-κB1 p105 prevents TPL-2 phosphorylation of MEK-1/2. LPS stimulation of TPL-2 MEK-1/2 kinase activity requires TPL-2 release from p105. This is triggered by IκB kinase 2 (IKK-2) phosphorylation of the p105 PEST region, which promotes p105 ubiquitination and degradation by the proteasome. LPS activation of ERK-1/2 additionally requires transphosphorylation of TPL-2 on serine 400 in its C terminus, which controls TPL-2 signaling to ERK-1/2 independently of p105. However, the identity of the protein kinase responsible for TPL-2 serine 400 phosphorylation remained unknown. In the present study, we show that TPL-2 serine 400 phosphorylation is mediated by IKK2. The IKK complex therefore regulates two of the key regulatory steps required for TPL-2 activation of ERK-1/2, underlining the close linkage of ERK-1/2 MAP kinase activation to upregulation of NF-κB-dependent transcription. PMID:22988300

  5. DEG9, a serine protease, modulates cytokinin and light signaling by regulating the level of ARABIDOPSIS RESPONSE REGULATOR 4

    PubMed Central

    Chi, Wei; Li, Jing; He, Baoye; Chai, Xin; Xu, Xiumei; Sun, Xuwu; Jiang, Jingjing; Feng, Peiqiang; Zuo, Jianru; Lin, Rongcheng; Rochaix, Jean-David; Zhang, Lixin

    2016-01-01

    Cytokinin is an essential phytohormone that controls various biological processes in plants. A number of response regulators are known to be important for cytokinin signal transduction. ARABIDOPSIS RESPONSE REGULATOR 4 (ARR4) mediates the cross-talk between light and cytokinin signaling through modulation of the activity of phytochrome B. However, the mechanism that regulates the activity and stability of ARR4 is unknown. Here we identify an ATP-independent serine protease, degradation of periplasmic proteins 9 (DEG9), which localizes to the nucleus and regulates the stability of ARR4. Biochemical evidence shows that DEG9 interacts with ARR4, thereby targeting ARR4 for degradation, which suggests that DEG9 regulates the stability of ARR4. Moreover, genetic evidence shows that DEG9 acts upstream of ARR4 and regulates the activity of ARR4 in cytokinin and light-signaling pathways. This study thus identifies a role for a ubiquitin-independent selective protein proteolysis in the regulation of the stability of plant signaling components. PMID:27274065

  6. Model-driven mapping of transcriptional networks reveals the circuitry and dynamics of virulence regulation.

    PubMed

    Maier, Ezekiel J; Haynes, Brian C; Gish, Stacey R; Wang, Zhuo A; Skowyra, Michael L; Marulli, Alyssa L; Doering, Tamara L; Brent, Michael R

    2015-05-01

    Key steps in understanding a biological process include identifying genes that are involved and determining how they are regulated. We developed a novel method for identifying transcription factors (TFs) involved in a specific process and used it to map regulation of the key virulence factor of a deadly fungus-its capsule. The map, built from expression profiles of 41 TF mutants, includes 20 TFs not previously known to regulate virulence attributes. It also reveals a hierarchy comprising executive, midlevel, and "foreman" TFs. When grouped by temporal expression pattern, these TFs explain much of the transcriptional dynamics of capsule induction. Phenotypic analysis of TF deletion mutants revealed complex relationships among virulence factors and virulence in mice. These resources and analyses provide the first integrated, systems-level view of capsule regulation and biosynthesis. Our methods dramatically improve the efficiency with which transcriptional networks can be analyzed, making genomic approaches accessible to laboratories focused on specific physiological processes.

  7. 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

  8. Wnt signaling regulates homeostasis of the periodontal ligament

    PubMed Central

    Lim, W.H.; Liu, B.; Cheng, D.; Williams, B.O.; Mah, S.J.; Helms, J.A.

    2014-01-01

    Background and Objective In health, the periodontal ligament maintains a constant width throughout an organism’s lifetime. The molecular signals responsible for maintaining homeostatic control over the periodontal ligament are unknown. The purpose of this study was to investigate the role of Wnt signaling in this process by removing an essential chaperone protein, Wntless (Wls) from odontoblasts and cementoblasts, and observing the effects of Wnt depletion on cells of the periodontal complex. Material and Methods The Wnt responsive status of the periodontal complex was assessed using two strains of Wnt reporter mice, Axin2LacZ/+ mice and Lgr5LacZ/+. The function of this endogenous Wnt signal was evaluated by conditionally eliminating the Wntless (Wls) gene using an Osteocalcin Cre driver. The resulting OCN-Cre;Wlsfl/fl mice were examined using micro-CT and histology, immunohistochemical analyses for Osteopontin, Runx2 and Fibromodulin, in situ hybridization for Osterix, and alkaline phosphatase activity. Results The adult periodontal ligament is Wnt responsive. Elimination of Wnt signaling in the periodontal complex of OCN-Cre;Wlsfl/fl mice results in a wider periodontal ligament space. This pathologically increased periodontal width is due to a reduction in the expression of osteogenic genes and proteins, which results in thinner alveolar bone. A concomitant increase in fibrous tissue occupying the periodontal space was observed along with a disruption in the orientation of the periodontal ligament. Conclusion The periodontal ligament is a Wnt dependent tissue. Cells in the periodontal complex are Wnt responsive and eliminating an essential component of the Wnt signaling network leads to a pathological widening of the periodontal ligament space. Osteogenic stimuli are reduced and a disorganized fibrillary matrix results from depletion of Wnt signaling. Collectively, these data underscore the importance of Wnt signaling in homeostasis of the periodontal ligament

  9. Androgen receptor signaling regulates growth of glioblastoma multiforme in men.

    PubMed

    Yu, Xiaoming; Jiang, Yuhua; Wei, Wei; Cong, Ping; Ding, Yinlu; Xiang, Lei; Wu, Kang

    2015-02-01

    Although glioblastoma multiforme (GBM) is the most malignant primary human brain cancer with surprisingly high incidence rate in adult men than in women, the exact mechanism underlying this pronounced epidemiology is unclear. Here, we showed significant upregulated androgen receptor (AR) expression in the GBM tissue compared to the periphery normal brain tissue in patients. An expression of AR was further detected in all eight examined human GBM cell lines. To figure out whether AR signaling may play a role in GBM, we used high AR-expressing U87-MG GBM line for further study. We found that activation of transforming growth factor β (TGFβ) receptor signaling by TGFβ1 in GBM significantly inhibited cell growth and increased apoptosis. Moreover, application of active AR ligand 5α-dihydrotestosterone (DHT) significantly decreased the effect of TGFβ1 on GBM growth and apoptosis, suggesting that AR signaling pathway may contradict the effect of TGFβ receptor signaling in GBM. However, neither total protein nor the phosphorylated protein of SMAD3, a major TGFβ receptor signaling downstream effector in GBM, was affected by DHT, suggesting that AR activation may not affect the SMAD3 protein production or phosphorylation of TGFβ receptor and SMAD3. Finally, immunoprecipitation followed by immunoblot confirmed binding of pAR to pSMAD3, which may prevent the DNA binding of pSMAD3 and subsequently prevent its effect on cell growth in GBM. Taken together, our study suggests that AR signaling may promote tumorigenesis of GBM in adult men by inhibiting TGFβ receptor signaling.

  10. Post-Transcriptional Regulation of Cytokine Signaling by AU-Rich and GU-Rich Elements

    PubMed Central

    Bohjanen, Paul R.

    2014-01-01

    Cytokines are necessary for cell communication to enable responses to external stimuli that are imperative for the survival and maintenance of homeostasis. Dysfunction of the cytokine network has detrimental effects on intra- and extracellular environments. Thus, it is critical that the expression of cytokines and the signals transmitted by cytokines to target cells are tightly regulated at numerous levels, including transcriptional and post-transcriptional levels. Here, we briefly summarize the role of AU-rich elements (AREs) in the regulation of cytokine gene expression at the post-transcriptional level and describe a role for GU-rich elements (GREs) in coordinating the regulation of cytokine signaling. GREs function as post-transcriptional regulators of proteins that control cellular activation, growth, and apoptosis. GREs and AREs work in concert to coordinate cytokine signal transduction pathways. The precise regulation of cytokine signaling is particularly important, because its dysregulation can lead to human diseases. PMID:24697201

  11. 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

  12. Notch signaling regulates cardiomyocyte proliferation during zebrafish heart regeneration.

    PubMed

    Zhao, Long; Borikova, Asya L; Ben-Yair, Raz; Guner-Ataman, Burcu; MacRae, Calum A; Lee, Richard T; Burns, C Geoffrey; Burns, Caroline E

    2014-01-28

    The human heart's failure to replace ischemia-damaged myocardium with regenerated muscle contributes significantly to the worldwide morbidity and mortality associated with coronary artery disease. Remarkably, certain vertebrate species, including the zebrafish, achieve complete regeneration of amputated or injured myocardium through the proliferation of spared cardiomyocytes. Nonetheless, the genetic and cellular determinants of natural cardiac regeneration remain incompletely characterized. Here, we report that cardiac regeneration in zebrafish relies on Notch signaling. Following amputation of the zebrafish ventricular apex, Notch receptor expression becomes activated specifically in the endocardium and epicardium, but not the myocardium. Using a dominant negative approach, we discovered that suppression of Notch signaling profoundly impairs cardiac regeneration and induces scar formation at the amputation site. We ruled out defects in endocardial activation, epicardial activation, and dedifferentiation of compact myocardial cells as causative for the regenerative failure. Furthermore, coronary endothelial tubes, which we lineage traced from preexisting endothelium in wild-type hearts, formed in the wound despite the myocardial regenerative failure. Quantification of myocardial proliferation in Notch-suppressed hearts revealed a significant decrease in cycling cardiomyocytes, an observation consistent with a noncell autonomous requirement for Notch signaling in cardiomyocyte proliferation. Unexpectedly, hyperactivation of Notch signaling also suppressed cardiomyocyte proliferation and heart regeneration. Taken together, our data uncover the exquisite sensitivity of regenerative cardiomyocyte proliferation to perturbations in Notch signaling.

  13. 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.

  14. Post-transcriptional regulation of interferons and their signaling pathways.

    PubMed

    Savan, Ram

    2014-05-01

    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.

  15. 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

  16. 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

  17. Regulator of G-protein signaling (RGS) proteins in cancer biology.

    PubMed

    Hurst, Jillian H; Hooks, Shelley B

    2009-11-15

    The regulator of G-protein signaling (RGS) family is a diverse group of multifunctional proteins that regulate cellular signaling events downstream of G-protein coupled receptors (GPCRs). In recent years, GPCRs have been linked to the initiation and progression of multiple cancers; thus, regulators of GPCR signaling are also likely to be important to the pathophysiology of cancer. This review highlights recent studies detailing changes in RGS transcript expression during oncogenesis, single nucleotide polymorphisms in RGS proteins linked to lung and bladder cancers, and specific roles for RGS proteins in multiple cancer types.

  18. 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

  19. HER2 signaling regulates HER2 localization and membrane retention

    PubMed Central

    Jeong, Jaekwang; Kim, Wonnam; Kim, Lark Kyun; VanHouten, Joshua; Wysolmerski, John J.

    2017-01-01

    ErbB2/HER2/Neu is a receptor tyrosine kinase that is overexpressed in 25–30% of human breast cancers, usually associated with amplification of the ERBB2 gene. HER2 has no recognized ligands and heterodimers between HER2 and EGFR (ErbB1/HER1) or HER2 and ErbB3/HER3 are important in breast cancer. Unlike other ErbB family members, HER2 is resistant to internalization and degradation, and remains at the cell surface to signal for prolonged periods after it is activated. Although the mechanisms underlying retention of HER2 at the cell surface are not fully understood, prior studies have shown that, in order to avoid internalization, HER2 must interact with the chaperone, HSP90, and the calcium pump, PMCA2, within specific plasma membrane domains that protrude from the cell surface. In this report, we demonstrate that HER2 signaling, itself, is important for the formation and maintenance of membrane protrusions, at least in part, by maintaining PMCA2 expression and preventing increased intracellular calcium concentrations. Partial genetic knockdown of HER2 expression or pharmacologic inhibition of HER2 signaling causes the depletion of membrane protrusions and disruption of the interactions between HER2 and HSP90. This is associated with the ubiquitination of HER2, its internalization with EGFR or HER3, and its degradation. These results suggest a model by which some threshold of HER2 signaling is required for the formation and/or maintenance of multi-protein signaling complexes that reinforce and prolong HER2/EGFR or HER2/HER3 signaling by inhibiting HER2 ubiquitination and internalization. PMID:28369073

  20. 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.

  1. 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.

  2. Gut-neuron interaction via Hh signaling regulates intestinal progenitor cell differentiation in Drosophila.

    PubMed

    Han, Hui; Pan, Chenyu; Liu, Chunying; Lv, Xiangdong; Yang, Xiaofeng; Xiong, Yue; Lu, Yi; Wu, Wenqing; Han, Junhai; Zhou, Zhaocai; Jiang, Hai; Zhang, Lei; Zhao, Yun

    2015-01-01

    Intestinal homeostasis is maintained by intestinal stem cells (ISCs) and their progenies. A complex autonomic nervous system spreads over posterior intestine. However, whether and how neurons regulate posterior intestinal homeostasis is largely unknown. Here we report that neurons regulate Drosophila posterior intestinal homeostasis. Specifically, downregulation of neuronal Hedgehog (Hh) signaling inhibits the differentiation of ISCs toward enterocytes (ECs), whereas upregulated neuronal Hh signaling promotes such process. We demonstrate that, among multiple sources of Hh ligand, those secreted by ECs induces similar phenotypes as does neuronal Hh. In addition, intestinal JAK/STAT signaling responds to activated neuronal Hh signaling, suggesting that JAK/STAT signaling acts downstream of neuronal Hh signaling in intestine. Collectively, our results indicate that neuronal Hh signaling is essential for the determination of ISC fate.

  3. 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.

  4. GPR30 Signaling and Regulation in Breast Cancer

    DTIC Science & Technology

    2011-04-01

    GPCR ), GPR30, was shown to elicit E2-dependent signaling in SKBr3 cells, which lack both classical E2 receptors [4]. In 2005, our group and...we have determined by immunofluorescent antibody staining that they are GPR30 positive. We also used a PyMT cell line derived from the tumor of a

  5. G proteins as regulators in ethylene-mediated hypoxia signaling.

    PubMed

    Steffens, Bianka; Sauter, Margret

    2010-04-01

    Waterlogging or flooding are frequently or constitutively encountered by many plant species. The resulting reduction in endogenous O2 concentration poses a severe threat. Numerous adaptations at the anatomical, morphological and metabolic level help plants to either escape low oxygen conditions or to endure them. Formation of aerenchyma or rapid shoot elongation are escape responses, as is the formation of adventitious roots. The metabolic shift from aerobic respiration to anaerobic fermentation contributes to a basal energy supply at low oxygen conditions. Ethylene plays a central role in hypoxic stress signaling, and G proteins have been recognized as crucial signal transducers in various hypoxic signaling pathways. The programmed death of parenchyma cells that results in hypoxia-induced aerenchyma formation is an ethylene response. In maize, aerenchyma are induced in the absence of ethylene when G proteins are constitutively activated. Similarly, ethylene induced death of epidermal cells that cover adventitious roots at the stem node of rice is strictly dependent on heterotrimeric G protein activity. Knock down of the unique Gα gene RGA1 in rice prevents epidermal cell death. Finally, in Arabidopsis, induction of alcohol dehydrogenase with resulting increased plant survival relies on the balanced activities of a small Rop G protein and its deactivating protein RopGAP4. Identifying the general mechanisms of G protein signaling in hypoxia adaptation of plants is one of the tasks ahead.

  6. Insulin Signaling Regulates Fatty Acid Catabolism at the Level of CoA Activation

    PubMed Central

    Xu, Xiaojun; Gopalacharyulu, Peddinti; Seppänen-Laakso, Tuulikki; Ruskeepää, Anna-Liisa; Aye, Cho Cho; Carson, Brian P.; Mora, Silvia; Orešič, Matej; Teleman, Aurelio A.

    2012-01-01

    The insulin/IGF signaling pathway is a highly conserved regulator of metabolism in flies and mammals, regulating multiple physiological functions including lipid metabolism. Although insulin signaling is known to regulate the activity of a number of enzymes in metabolic pathways, a comprehensive understanding of how the insulin signaling pathway regulates metabolic pathways is still lacking. Accepted knowledge suggests the key regulated step in triglyceride (TAG) catabolism is the release of fatty acids from TAG via the action of lipases. We show here that an additional, important regulated step is the activation of fatty acids for beta-oxidation via Acyl Co-A synthetases (ACS). We identify pudgy as an ACS that is transcriptionally regulated by direct FOXO action in Drosophila. Increasing or reducing pudgy expression in vivo causes a decrease or increase in organismal TAG levels respectively, indicating that pudgy expression levels are important for proper lipid homeostasis. We show that multiple ACSs are also transcriptionally regulated by insulin signaling in mammalian cells. In sum, we identify fatty acid activation onto CoA as an important, regulated step in triglyceride catabolism, and we identify a mechanistic link through which insulin regulates lipid homeostasis. PMID:22275878

  7. Tbx2 regulates anterior neural specification by repressing FGF signaling pathway.

    PubMed

    Cho, Gun-Sik; Park, Dong-Seok; Choi, Sun-Cheol; Han, Jin-Kwan

    2017-01-15

    During early embryogenesis, FGF signals regulate the antero-posterior (AP) patterning of the neural plate by promoting posterior cell fates. In particular, BMP signal-mediated attenuation of FGF pathway plays a critical role in the determination of the anterior neural region. Here we show that Tbx2, a T-box transcriptional repressor regulates anterior neural specification by suppressing FGF8 signaling pathway in Xenopus embryo. Tbx2 is expressed in the anterior edge of the neural plate in early neurulae. Overexpression and knockdown of Tbx2 induce expansion and reduction in the expression of anterior neural markers, respectively. It also suppresses FGF8-induced ERK phosphorylation and neural caudalization. Tbx2, which is a target gene of BMP signal, down-regulates FGF8 signaling by inhibiting the expression of Flrt3, a positive regulator of this pathway. We found that Tbx2 binds directly to the T-box element located in the promoter region of Flrt3 gene, thereby interfering with the activity of the promoter. Consistently, Tbx2 augmentation of anterior neural formation is inhibited by co-expression of Flrt3. Furthermore, disruption of the anterior-most structures such as eyes in Tbx2-depleted embryos can be rescued by inhibition of Flrt3 function or FGF signaling. Taken together, our results suggest that Tbx2 mediates BMP signal to down-regulate FGF signaling pathway by repressing Flrt3 expression for anterior tissue formation.

  8. microRNA regulation of Wnt signaling pathways in development and disease

    PubMed Central

    Song, Jia L.; Nigam, Priya; Tektas, Senel S.; Selva, Erica

    2015-01-01

    Wnt signaling pathways and microRNAs (miRNAs) are critical regulators of development. Aberrant Wnt signaling pathways and miRNA levels lead to developmental defects and diverse human pathologies including but not limited to cancer. Wnt signaling pathways regulate a plethora of cellular processes during embryonic development and maintain homeostasis of adult tissues. A majority of Wnt signaling components are regulated by miRNAs which are small noncoding RNAs that are expressed in both animals and plants. In animal cells, miRNAs fine tune gene expression by pairing primarily to the 3′untranslated region of protein coding mRNAs to repress target mRNA translation and/or induce target degradation. miRNA-mediated regulation of signaling transduction pathways is important in modulating dose-sensitive response of cells to signaling molecules. This review discusses components of the Wnt signaling pathways that are regulated by miRNAs in the context of development and diseases. A fundamental understanding of miRNA functions in Wnt signaling transduction pathways may yield new insight into crosstalks of regulatory mechanisms essential for development and disease pathophysiology leading to novel therapeutics. PMID:25843779

  9. Regulation of Hh/Gli signaling by dual ubiquitin pathways.

    PubMed

    Jiang, Jin

    2006-11-01

    The Hedgehog (Hh) signaling pathway governs cell growth and patterning in animal development. Malfunction of several pathway components, including the key transcriptional effector Ci/Gli proteins, leads to a variety of human disorders including several malignancies. Ci/Gli activity is controlled by multi-layered regulatory mechanisms, the most prominent of which is the ubiquitin-mediated proteolysis. In the absence of Hh, Ci/Gli is proteolytically processed into a truncated form that functions as a transcriptional repressor of the Hh pathway. Ci processing is mediated by an SCF (Skip1/Cul1/F-box protein) ubiquitin ligase in which the F-box protein Slimb/beta-TRCP bridges Ci to the ubiquitin ligase. Recent studies in Drosophila and mammalian cultured cells have demonstrated that sequential phosphorylation of Ci/Gli by PKA, GSK3, and CKI creates multiple docking sites that can recruit SCF(Slimb/beta-TRCP), which then promotes Ci/Gli ubiquitination followed by proteasome-mediated processing. Recently, an E3 ubiquitin ligase consisting of the BTB (Broad Complex, Tramtrack, and Bric a Brac) protein HIB (Hh induced MATH and BTB protein) and Cullin 3 (Cul3) has been identified that acts in a negative feedback loop to fine-tune Hh signaling responses by degrading full length Ci. In eye imaginal discs where Hh signals coordinate cell proliferation and differentiation, HIB is highly expressed in the differentiating cells to prevent aberrant Hh signaling activity and ensure normal eye development. Tissue- and developmental stage-specific expression of HIB and its homologs in vertebrates may provide a conserved mechanism for ensuring precision in spatial and temporal control of Hh signaling.

  10. Glial Cell Calcium Signaling Mediates Capillary Regulation of Blood Flow in the Retina

    PubMed Central

    Biesecker, Kyle R.; Srienc, Anja I.; Shimoda, Angela M.; Agarwal, Amit; Bergles, Dwight E.; Kofuji, Paulo

    2016-01-01

    The brain is critically dependent on the regulation of blood flow to nourish active neurons. One widely held hypothesis of blood flow regulation holds that active neurons stimulate Ca2+ increases in glial cells, triggering glial release of vasodilating agents. This hypothesis has been challenged, as arteriole dilation can occur in the absence of glial Ca2+ signaling. We address this controversy by imaging glial Ca2+ signaling and vessel dilation in the mouse retina. We find that sensory stimulation results in Ca2+ increases in the glial endfeet contacting capillaries, but not arterioles, and that capillary dilations often follow spontaneous Ca2+ signaling. In IP3R2−/− mice, where glial Ca2+ signaling is reduced, light-evoked capillary, but not arteriole, dilation is abolished. The results show that, independent of arterioles, capillaries actively dilate and regulate blood flow. Furthermore, the results demonstrate that glial Ca2+ signaling regulates capillary but not arteriole blood flow. SIGNIFICANCE STATEMENT We show that a Ca2+-dependent glial cell signaling mechanism is responsible for regulating capillary but not arteriole diameter. This finding resolves a long-standing controversy regarding the role of glial cells in regulating blood flow, demonstrating that glial Ca2+ signaling is both necessary and sufficient to dilate capillaries. While the relative contributions of capillaries and arterioles to blood flow regulation remain unclear, elucidating the mechanisms that regulate capillary blood flow may ultimately lead to the development of therapies for treating diseases where blood flow regulation is disrupted, including Alzheimer's disease, stroke, and diabetic retinopathy. This finding may also aid in revealing the underlying neuronal activity that generates BOLD fMRI signals. PMID:27605617

  11. Mapping and correction of vascular hemodynamic latency in the BOLD signal.

    PubMed

    Chang, Catie; Thomason, Moriah E; Glover, Gary H

    2008-10-15

    Correlation and causality metrics can be applied to blood-oxygen level-dependent (BOLD) signal time series in order to infer neural synchrony and directions of information flow from fMRI data. However, the BOLD signal reflects both the underlying neural activity and the vascular response, the latter of which is governed by local vasomotor physiology. The presence of potential vascular latency differences thus poses a confound in the detection of neural synchrony as well as inferences about the causality of neural processes. In the present study, we investigate the use of a breath holding (BH) task for characterizing and correcting for voxel-wise neurovascular latency differences across the whole brain. We demonstrate that BH yields reliable measurements of relative timing differences between voxels, and further show that a BH-derived latency correction can impact both functional connectivity maps of the resting-state default-mode network and activation maps of an event-related working memory (WM) task.

  12. Modeling the effects of distortion, contrast, and signal-to-noise ratio on stereophotogrammetric range mapping

    NASA Astrophysics Data System (ADS)

    Sellar, R. Glenn; Deen, Robert G.; Huffman, William C.; Willson, Reginald G.

    2016-09-01

    Stereophotogrammetry typically employs a pair of cameras, or a single moving camera, to acquire pairs of images from different camera positions, in order to create a three dimensional `range map' of the area being observed. Applications of this technique for building three-dimensional shape models include aerial surveying, remote sensing, machine vision, and robotics. Factors that would be expected to affect the quality of the range maps include the projection function (distortion) of the lenses and the contrast (modulation) and signal-to-noise ratio (SNR) of the acquired image pairs. Basic models of the precision with which the range can be measured assume a pinhole-camera model of the geometry, i.e. that the lenses provide perspective projection with zero distortion. Very-wide-angle or `fisheye' lenses, however (for e.g. those used by robotic vehicles) typically exhibit projection functions that differ significantly from this assumption. To predict the stereophotogrammetric range precision for such applications, we extend the model to the case of an equidistant lens projection function suitable for a very-wide-angle lens. To predict the effects of contrast and SNR on range precision, we perform numerical simulations using stereo image pairs acquired by a stereo camera pair on NASA's Mars rover Curiosity. Contrast is degraded and noise is added to these data in a controlled fashion and the effects on the quality of the resulting range maps are assessed.

  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. Novel regulator of enterohepatic bile acid signaling protects against hypercholesterolemia.

    PubMed

    Dawson, Paul A

    2013-06-04

    Hypercholesterolemia is a major cause of cardiovascular disease and can be treated by targeting bile acid and cholesterol metabolism. Vergnes et al. (2013) now identify Diet1 as a novel regulator of fibroblast growth factor 15/19 production and bile acid biosynthesis.

  15. Lysophospholipid receptors: signalling, pharmacology and regulation by lysophospholipid metabolism.

    PubMed

    Meyer zu Heringdorf, Dagmar; Jakobs, Karl H

    2007-04-01

    The lysophospholipids, sphingosine-1-phosphate (S1P), lysophosphatidic acid (LPA), sphingosylphosphorylcholine (SPC) and lysophosphatidylcholine (LPC), activate diverse groups of G-protein-coupled receptors that are widely expressed and regulate decisive cellular functions. Receptors of the endothelial differentiation gene family are activated by S1P (S1P(1-5)) or LPA (LPA(1-3)); two more distantly related receptors are activated by LPA (LPA(4/5)); the GPR(3/6/12) receptors have a high constitutive activity but are further activated by S1P and/or SPC; and receptors of the OGR1 cluster (OGR1, GPR4, G2A, TDAG8) appear to be activated by SPC, LPC, psychosine and/or protons. G-protein-coupled lysophospholipid receptors regulate cellular Ca(2+) homoeostasis and the cytoskeleton, proliferation and survival, migration and adhesion. They have been implicated in development, regulation of the cardiovascular, immune and nervous systems, inflammation, arteriosclerosis and cancer. The availability of S1P and LPA at their G-protein-coupled receptors is regulated by enzymes that generate or metabolize these lysophospholipids, and localization plays an important role in this process. Besides FTY720, which is phosphorylated by sphingosine kinase-2 and then acts on four of the five S1P receptors of the endothelial differentiation gene family, other compounds have been identified that interact with more ore less selectivity with lysophospholipid receptors.

  16. 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.

  17. 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.

  18. 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.

  19. Mechanotransduction and the Regulation of mTORC1 Signaling in Skeletal Muscle

    PubMed Central

    Hornberger, Troy A.

    2011-01-01

    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

  20. Products of lipid, protein and RNA oxidation as signals and regulators of gene expression in plants

    PubMed Central

    Chmielowska-Bąk, Jagna; Izbiańska, Karolina; Deckert, Joanna

    2015-01-01

    Reactive oxygen species (ROS) are engaged in several processes essential for normal cell functioning, such as differentiation, anti-microbial defense, stimulus sensing and signaling. Interestingly, recent studies imply that cellular signal transduction and gene regulation are mediated not only directly by ROS but also by the molecules derived from ROS-mediated oxidation. Lipid peroxidation leads to non-enzymatic formation of oxylipins. These molecules were shown to modulate expression of signaling associated genes including genes encoding phosphatases, kinases and transcription factors. Oxidized peptides derived from protein oxidation might be engaged in organelle-specific ROS signaling. In turn, oxidation of particular mRNAs leads to decrease in the level of encoded proteins and thus, contributes to the post-transcriptional regulation of gene expression. Present mini review summarizes latest findings concerning involvement of products of lipid, protein and RNA oxidation in signal transduction and gene regulation. PMID:26082792

  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. Bioelectric signaling regulates head and organ size during planarian regeneration

    PubMed Central

    Beane, Wendy Scott; Morokuma, Junji; Lemire, Joan M.; Levin, Michael

    2013-01-01

    A main goal of regenerative medicine is to replace lost or damaged tissues and organs with functional parts of the correct size and shape. But the proliferation of new cells is not sufficient; we will also need to understand how the scale and ultimate form of newly produced tissues are determined. Using the planarian model system, we report that membrane voltage-dependent bioelectric signaling determines both head size and organ scaling during regeneration. RNA interference of the H+,K+-ATPase ion pump results in membrane hyperpolarization, which has no effect on the amount of new tissue (blastema) that is regenerated yet produces regenerates with tiny ‘shrunken’ heads and proportionally oversized pharynges. Our data show that this disproportionality results from a lack of the apoptosis required to adjust head and organ size and placement, highlighting apoptotic remodeling as the link between bioelectric signaling and the establishment of organ size during regeneration. PMID:23250205

  3. Body size regulation and insulin-like growth factor signaling.

    PubMed

    Hyun, Seogang

    2013-07-01

    How animals achieve their specific body size is a fundamental, but still largely unresolved, biological question. Over the past decades, studies on the insect model system have provided some important insights into the process of body size determination and highlighted the importance of insulin/insulin-like growth factor signaling. Fat body, the Drosophila counterpart of liver and adipose tissue, senses nutrient availability and controls larval growth rate by modulating peripheral insulin signaling. Similarly, insulin-like growth factor I produced from liver and muscle promotes postnatal body growth in mammals. Organismal growth is tightly coupled with the process of sexual maturation wherein the sex steroid hormone attenuates body growth. This review summarizes some important findings from Drosophila and mammalian studies that shed light on the general mechanism of animal size determination.

  4. Bioelectric signaling regulates head and organ size during planarian regeneration.

    PubMed

    Beane, Wendy Scott; Morokuma, Junji; Lemire, Joan M; Levin, Michael

    2013-01-15

    A main goal of regenerative medicine is to replace lost or damaged tissues and organs with functional parts of the correct size and shape. But the proliferation of new cells is not sufficient; we will also need to understand how the scale and ultimate form of newly produced tissues are determined. Using the planarian model system, we report that membrane voltage-dependent bioelectric signaling determines both head size and organ scaling during regeneration. RNA interference of the H(+),K(+)-ATPase ion pump results in membrane hyperpolarization, which has no effect on the amount of new tissue (blastema) that is regenerated yet produces regenerates with tiny 'shrunken' heads and proportionally oversized pharynges. Our data show that this disproportionality results from a lack of the apoptosis required to adjust head and organ size and placement, highlighting apoptotic remodeling as the link between bioelectric signaling and the establishment of organ size during regeneration.

  5. Regulation of Wnt/β-catenin signaling by herpesviruses

    PubMed Central

    Zwezdaryk, Kevin J; Combs, Joseph A; Morris, Cindy A; Sullivan, Deborah E

    2016-01-01

    The Wnt/β-catenin signaling pathway is instrumental in successful differentiation and proliferation of mammalian cells. It is therefore not surprising that the herpesvirus family has developed mechanisms to interact with and manipulate this pathway. Successful coexistence with the host requires that herpesviruses establish a lifelong infection that includes periods of latency and reactivation or persistence. Many herpesviruses establish latency in progenitor cells and viral reactivation is linked to host-cell proliferation and differentiation status. Importantly, Wnt/β-catenin is tightly connected to stem/progenitor cell maintenance and differentiation. Numerous studies have linked Wnt/β-catenin signaling to a variety of cancers, emphasizing the importance of Wnt/β-catenin pathways in development, tissue homeostasis and disease. This review details how the alpha-, beta-, and gammaherpesviruses interact and manipulate the Wnt/β-catenin pathway to promote a virus-centric agenda. PMID:27878101

  6. Adiponectin Signaling Regulates Lipid Production in Human Sebocytes

    PubMed Central

    Jung, Yu Ra; Lee, Jin-Hyup; Sohn, Kyung-Cheol; Lee, Young; Seo, Young-Joon; Kim, Chang-Deok; Lee, Jeung-Hoon; Hong, Seung-Phil; Seo, Seong-Jun; Kim, Seong-Jin; Im, Myung

    2017-01-01

    Adiponectin plays important roles in metabolic function, inflammation and multiple biological activities in various tissues. However, evidence for adiponectin signaling in sebaceous glands is lacking, and its role remains to be clarified. This study investigated the role of adiponectin in lipid production in sebaceous glands in an experimental study of human sebocytes. We demonstrated that human sebaceous glands in vivo and sebocytes in vitro express adiponectin receptor and that adiponectin increased cell proliferation. Moreover, based on a lipogenesis study using Oil Red O, Nile red staining and thin layer chromatography, adiponectin strongly upregulated lipid production in sebocytes. In three-dimensional culture of sebocytes, lipid synthesis was markedly enhanced in sebocytes treated with adiponectin. This study suggested that adiponectin plays a significant role in human sebaceous gland biology. Adiponectin signaling is a promising target in the clinical management of barrier disorders in which sebum production is decreased, such as in atopic dermatitis and aged skin. PMID:28081218

  7. 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

  8. Neutrophil homeostasis and its regulation by danger signaling.

    PubMed

    Wirths, Stefan; Bugl, Stefanie; Kopp, Hans-Georg

    2014-06-05

    Hematopoiesis in general is demand driven and adaptive, but in contrast to erythropoiesis or thrombocytopoiesis, our knowledge on how neutrophil production is adapted to individual needs remains incomplete. Recently, neutrophil homeostasis has been shown to depend on danger receptors, macrophages, and even circadian rhythms. Puzzle pieces for a broader view of neutrophil homeostasis accumulate, and we will herein try to put seemingly contradictory evidence in a perspective of neutrophil homeostasis and emergency granulopoiesis determined by innate immunologic signaling.

  9. Neuropilin-1-dependent regulation of EGF-receptor signaling.

    PubMed

    Rizzolio, Sabrina; Rabinowicz, Noa; Rainero, Elena; Lanzetti, Letizia; Serini, Guido; Norman, Jim; Neufeld, Gera; Tamagnone, Luca

    2012-11-15

    Neuropilin-1 (NRP1) is a coreceptor for multiple extracellular ligands. NRP1 is widely expressed in cancer cells and in advanced human tumors; however, its functional relevance and signaling mechanisms are unclear. Here, we show that NRP1 expression controls viability and proliferation of different cancer cells, independent of its short intracellular tail. We found that the extracellular domain of NRP1 interacts with the EGF receptor (EGFR) and promotes its signaling cascade elicited upon EGF or TGF-α stimulation. Upon NRP1 silencing, the ability of ligand-bound EGFR to cluster on the cell surface, internalize, and activate the downstream AKT pathway is severely impaired. EGFR is frequently activated in human tumors due to overexpression, mutation, or sustained autocrine/paracrine stimulation. Here we show that NRP1-blocking antibodies and NRP1 silencing can counteract ligand-induced EGFR activation in cancer cells. Thus our findings unveil a novel molecular mechanism by which NRP1 can control EGFR signaling and tumor growth.

  10. Primary cilia regulate hippocampal neurogenesis by mediating sonic hedgehog signaling

    PubMed Central

    Breunig, Joshua J.; Sarkisian, Matthew R.; Arellano, Jon I.; Morozov, Yury M.; Ayoub, Albert E.; Sojitra, Sonal; Wang, Baolin; Flavell, Richard A.; Rakic, Pasko; Town, Terrence

    2008-01-01

    Primary cilia are present on mammalian neurons and glia, but their function is largely unknown. We generated conditional homozygous mutant mice for a gene we termed Stumpy. Mutants lack cilia and have conspicuous abnormalities in postnatally developing brain regions, including a hypoplasic hippocampus characterized by a primary deficiency in neural stem cells known as astrocyte-like neural precursors (ALNPs). Previous studies suggested that primary cilia mediate sonic hedgehog (Shh) signaling. Here, we find that loss of ALNP cilia leads to abrogated Shh activity, increased cell cycle exit, and morphological abnormalities in ALNPs. Processing of Gli3, a mediator of Shh signaling, is also altered in the absence of cilia. Further, key mediators of the Shh pathway localize to ALNP cilia. Thus, selective targeting of Shh machinery to primary cilia confers to ALNPs the ability to differentially respond to Shh mitogenic signals compared to neighboring cells. Our data suggest these organelles are cellular “antennae” critically required to modulate ALNP behavior. PMID:18728187

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

    PubMed

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

    2014-01-01

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

  12. Reconstruction of signaling networks regulating fungal morphogenesis by transcriptomics.

    PubMed

    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

    2009-11-01

    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.

  13. Maps of context-dependent putative regulatory regions and genomic signal interactions.

    PubMed

    Diamanti, Klev; Umer, Husen M; Kruczyk, Marcin; Dąbrowski, Michał J; Cavalli, Marco; Wadelius, Claes; Komorowski, Jan

    2016-11-02

    Gene transcription is regulated mainly by transcription factors (TFs). ENCODE and Roadmap Epigenomics provide global binding profiles of TFs, which can be used to identify regulatory regions. To this end we implemented a method to systematically construct cell-type and species-specific maps of regulatory regions and TF-TF interactions. We illustrated the approach by developing maps for five human cell-lines and two other species. We detected ∼144k putative regulatory regions among the human cell-lines, with the majority of them being ∼300 bp. We found ∼20k putative regulatory elements in the ENCODE heterochromatic domains suggesting a large regulatory potential in the regions presumed transcriptionally silent. Among the most significant TF interactions identified in the heterochromatic regions were CTCF and the cohesin complex, which is in agreement with previous reports. Finally, we investigated the enrichment of the obtained putative regulatory regions in the 3D chromatin domains. More than 90% of the regions were discovered in the 3D contacting domains. We found a significant enrichment of GWAS SNPs in the putative regulatory regions. These significant enrichments provide evidence that the regulatory regions play a crucial role in the genomic structural stability. Additionally, we generated maps of putative regulatory regions for prostate and colorectal cancer human cell-lines.

  14. Mapping CRMP3 domains involved in dendrite morphogenesis and voltage-gated calcium channel regulation.

    PubMed

    Quach, Tam T; Wilson, Sarah M; Rogemond, Veronique; Chounlamountri, Naura; Kolattukudy, Pappachan E; Martinez, Stephanie; Khanna, May; Belin, Marie-Francoise; Khanna, Rajesh; Honnorat, Jerome; Duchemin, Anne-Marie

    2013-09-15

    Although hippocampal neurons are well-distinguished by the morphological characteristics of their dendrites and their structural plasticity, the mechanisms involved in regulating their neurite initiation, dendrite growth, network formation and remodeling are still largely unknown, in part because the key molecules involved remain elusive. Identifying new dendrite-active cues could uncover unknown molecular mechanisms that would add significant understanding to the field and possibly lead to the development of novel neuroprotective therapy because these neurons are impaired in many neuropsychiatric disorders. In our previous studies, we deleted the gene encoding CRMP3 in mice and identified the protein as a new endogenous signaling molecule that shapes diverse features of the hippocampal pyramidal dendrites without affecting axon morphology. We also found that CRMP3 protects dendrites against dystrophy induced by prion peptide PrP(106-126). Here, we report that CRMP3 has a profound influence on neurite initiation and dendrite growth of hippocampal neurons in vitro. Our deletional mapping revealed that the C-terminus of CRMP3 probably harbors its dendritogenic capacity and supports an active transport mechanism. By contrast, overexpression of the C-terminal truncated CRMP3 phenocopied the effect of CRMP3 gene deletion with inhibition of neurite initiation or decrease in dendrite complexity, depending on the stage of cell development. In addition, this mutant inhibited the activity of CRMP3, in a similar manner to siRNA. Voltage-gated calcium channel inhibitors prevented CRMP3-induced dendritic growth and somatic Ca(2+) influx in CRMP3-overexpressing neurons was augmented largely via L-type channels. These results support a link between CRMP3-mediated Ca(2+) influx and CRMP3-mediated dendritic growth in hippocampal neurons.

  15. 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.

  16. Scaffold mediated regulation of MAPK signaling and cytoskeletal dynamics: A perspective

    PubMed Central

    Pullikuth, Ashok K.; Catling, Andrew D.

    2008-01-01

    Cell migration is critical for many physiological processes and is often misregulated in developmental disorders and pathological conditions including cancer and neurodegeneration. MAPK signaling and the Rho family of proteins are known regulators of cell migration that exert their influence on cellular cytoskeleton during cell adhesion and migration. Here we review data supporting the view that localized ERK signaling mediated through recently identified scaffold proteins may regulate cell migration. PMID:17553668

  17. N-WASP Is Essential for the Negative Regulation of B Cell Receptor Signaling

    PubMed Central

    Liu, Chaohong; Bai, Xiaoming; Wu, Junfeng; Sharma, Shruti; Upadhyaya, Arpita; Dahlberg, Carin I. M.; Westerberg, Lisa S.; Snapper, Scott B.; Zhao, Xiaodong; Song, Wenxia

    2013-01-01

    Negative regulation of receptor signaling is essential for controlling cell activation and differentiation. In B-lymphocytes, the down-regulation of B-cell antigen receptor (BCR) signaling is critical for suppressing the activation of self-reactive B cells; however, the mechanism underlying the negative regulation of signaling remains elusive. Using genetically manipulated mouse models and total internal reflection fluorescence microscopy, we demonstrate that neuronal Wiskott–Aldrich syndrome protein (N-WASP), which is coexpressed with WASP in all immune cells, is a critical negative regulator of B-cell signaling. B-cell–specific N-WASP gene deletion causes enhanced and prolonged BCR signaling and elevated levels of autoantibodies in the mouse serum. The increased signaling in N-WASP knockout B cells is concurrent with increased accumulation of F-actin at the B-cell surface, enhanced B-cell spreading on the antigen-presenting membrane, delayed B-cell contraction, inhibition in the merger of signaling active BCR microclusters into signaling inactive central clusters, and a blockage of BCR internalization. Upon BCR activation, WASP is activated first, followed by N-WASP in mouse and human primary B cells. The activation of N-WASP is suppressed by Bruton's tyrosine kinase-induced WASP activation, and is restored by the activation of SH2 domain-containing inositol 5-phosphatase that inhibits WASP activation. Our results reveal a new mechanism for the negative regulation of BCR signaling and broadly suggest an actin-mediated mechanism for signaling down-regulation. PMID:24223520

  18. 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

  19. Multilayered Organization of Jasmonate Signalling in the Regulation of Root Growth

    PubMed Central

    Gasperini, Debora; Chételat, Aurore; Acosta, Ivan F.; Goossens, Jonas; Pauwels, Laurens; Goossens, Alain; Dreos, René; Alfonso, Esteban; Farmer, Edward E.

    2015-01-01

    Physical damage can strongly affect plant growth, reducing the biomass of developing organs situated at a distance from wounds. These effects, previously studied in leaves, require the activation of jasmonate (JA) signalling. Using a novel assay involving repetitive cotyledon wounding in Arabidopsis seedlings, we uncovered a function of JA in suppressing cell division and elongation in roots. Regulatory JA signalling components were then manipulated to delineate their relative impacts on root growth. The new transcription factor mutant myc2-322B was isolated. In vitro transcription assays and whole-plant approaches revealed that myc2-322B is a dosage-dependent gain-of-function mutant that can amplify JA growth responses. Moreover, myc2-322B displayed extreme hypersensitivity to JA that totally suppressed root elongation. The mutation weakly reduced root growth in undamaged plants but, when the upstream negative regulator NINJA was genetically removed, myc2-322B powerfully repressed root growth through its effects on cell division and cell elongation. Furthermore, in a JA-deficient mutant background, ninja1 myc2-322B still repressed root elongation, indicating that it is possible to generate JA-responses in the absence of JA. We show that NINJA forms a broadly expressed regulatory layer that is required to inhibit JA signalling in the apex of roots grown under basal conditions. By contrast, MYC2, MYC3 and MYC4 displayed cell layer-specific localisations and MYC3 and MYC4 were expressed in mutually exclusive regions. In nature, growing roots are likely subjected to constant mechanical stress during soil penetration that could lead to JA production and subsequent detrimental effects on growth. Our data reveal how distinct negative regulatory layers, including both NINJA-dependent and -independent mechanisms, restrain JA responses to allow normal root growth. Mechanistic insights from this work underline the importance of mapping JA signalling components to specific

  20. VEGFR2 Trafficking, Signaling and Proteolysis is Regulated by the Ubiquitin Isopeptidase USP8.

    PubMed

    Smith, Gina A; Fearnley, Gareth W; Abdul-Zani, Izma; Wheatcroft, Stephen B; Tomlinson, Darren C; Harrison, Michael A; Ponnambalam, Sreenivasan

    2016-01-01

    Vascular endothelial growth factor A (VEGF-A) regulates many aspects of vascular function. VEGF-A binding to vascular endothelial growth factor receptor 2 (VEGFR2) stimulates endothelial signal transduction and regulates multiple cellular responses. Activated VEGFR2 undergoes ubiquitination but the enzymes that regulate this post-translational modification are unclear. In this study, the de-ubiquitinating enzyme, USP8, is shown to regulate VEGFR2 trafficking, de-ubiquitination, proteolysis and signal transduction. USP8-depleted endothelial cells displayed altered VEGFR2 ubiquitination and production of a unique VEGFR2 extracellular domain proteolytic fragment caused by VEGFR2 accumulation in the endosome-lysosome system. In addition, perturbed VEGFR2 trafficking impaired VEGF-A-stimulated signal transduction in USP8-depleted cells. Thus, regulation of VEGFR2 ubiquitination and de-ubiquitination has important consequences for the endothelial cell response and vascular physiology.

  1. 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.

  2. MAP Kinase-Mediated Negative Regulation of Symbiotic Nodule Formation in Medicago truncatula

    PubMed Central

    Ryu, Hojin; Laffont, Carole; Frugier, Florian; Hwang, Ildoo

    2017-01-01

    Mitogen-activated protein kinase (MAPK) signaling cascades play critical roles in various cellular events in plants, including stress responses, innate immunity, hormone signaling, and cell specificity. MAPK-mediated stress signaling is also known to negatively regulate nitrogen-fixing symbiotic interactions, but the molecular mechanism of the MAPK signaling cascades underlying the symbiotic nodule development remains largely unknown. We show that the MtMKK5-MtMPK3/6 signaling module negatively regulates the early symbiotic nodule formation, probably upstream of ERN1 (ERF Required for Nodulation 1) and NSP1 (Nod factor Signaling Pathway 1) in Medicago truncatula. The overexpression of MtMKK5 stimulated stress and defense signaling pathways but also reduced nodule formation in M. truncatula roots. Conversely, a MAPK specific inhibitor, U0126, enhanced nodule formation and the expression of an early nodulation marker gene, MtNIN. We found that MtMKK5 directly activates MtMPK3/6 by phosphorylating the TEY motif within the activation loop and that the MtMPK3/6 proteins physically interact with the early nodulation-related transcription factors ERN1 and NSP1. These data suggest that the stress signaling-mediated MtMKK5/MtMPK3/6 module suppresses symbiotic nodule development via the action of early nodulation transcription factors. PMID:28152300

  3. Tissue-specific Insulin Signaling in the Regulation of Metabolism and Aging

    PubMed Central

    Zhang, Jingjing

    2014-01-01

    In mammals, insulin signaling regulates glucose homeostasis and plays an essential role in metabolism, organ growth, development, fertility, and lifespan. Defects in this signaling pathway contribute to various metabolic diseases such as type 2 diabetes, polycystic ovarian disease, hypertension, hyperlipidemia, and atherosclerosis. However, reducing the insulin signaling pathway has been found to increase longevity and delay the aging-associated diseases in various animals, ranging from nematodes to mice. These seemly paradoxical findings raise an interesting question as to how modulation of the insulin signaling pathway could be an effective approach to improve metabolism and aging. In this review, we summarize current understanding on tissue-specific functions of insulin signaling in the regulation of metabolism and lifespan. We also discuss potential benefits and limitations in modulating tissue-specific insulin signaling pathway to improve metabolism and healthspan. PMID:25087968

  4. BRCA1 Regulation of Estrogen Signaling in the Breast

    DTIC Science & Technology

    2007-05-01

    commonly used in hormonal therapy (Fig. 4 of Appendix 1). Third , DBC-1 depletion reduces the steady-state level of unliganded, but not liganded, ERα...hormonal therapy (first- line treatment with an aromatase inhibitor followed by second- line treatment with an antiestrogen) leading to the acquisition of a...regulators of ERα, we used retroviral-mediated gene transfer to engineer a HeLaS3 cervical carcinoma-derived cell line (fERα/S3) that stably expresses

  5. 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.

  6. Crim1 regulates integrin signaling in murine lens development.

    PubMed

    Zhang, Ying; Fan, Jieqing; Ho, Joshua W K; Hu, Tommy; Kneeland, Stephen C; Fan, Xueping; Xi, Qiongchao; Sellarole, Michael A; de Vries, Wilhelmine N; Lu, Weining; Lachke, Salil A; Lang, Richard A; John, Simon W M; Maas, Richard L

    2016-01-15

    The developing lens is a powerful system for investigating the molecular basis of inductive tissue interactions and for studying cataract, the leading cause of blindness. The formation of tightly controlled cell-cell adhesions and cell-matrix junctions between lens epithelial (LE) cells, between lens fiber (LF) cells, and between these two cell populations enables the vertebrate lens to adopt a highly ordered structure and acquire optical transparency. Adhesion molecules are thought to maintain this ordered structure, but little is known about their identity or interactions. Cysteine-rich motor neuron 1 (Crim1), a type I transmembrane protein, is strongly expressed in the developing lens and its mutation causes ocular disease in both mice and humans. How Crim1 regulates lens morphogenesis is not understood. We identified a novel ENU-induced hypomorphic allele of Crim1, Crim1(glcr11), which in the homozygous state causes cataract and microphthalmia. Using this and two other mutant alleles, Crim1(null) and Crim1(cko), we show that the lens defects in Crim1 mouse mutants originate from defective LE cell polarity, proliferation and cell adhesion. Crim1 adhesive function is likely to be required for interactions both between LE cells and between LE and LF cells. We show that Crim1 acts in LE cells, where it colocalizes with and regulates the levels of active β1 integrin and of phosphorylated FAK and ERK. The RGD and transmembrane motifs of Crim1 are required for regulating FAK phosphorylation. These results identify an important function for Crim1 in the regulation of integrin- and FAK-mediated LE cell adhesion during lens development.

  7. Myostatin regulates cardiomyocyte growth through modulation of Akt signaling.

    PubMed

    Morissette, Michael R; Cook, Stuart A; Foo, ShiYin; McKoy, Godfrina; Ashida, Noboru; Novikov, Mikhail; Scherrer-Crosbie, Marielle; Li, Ling; Matsui, Takashi; Brooks, Gavin; Rosenzweig, Anthony

    2006-07-07

    Myostatin is a highly conserved, potent negative regulator of skeletal muscle hypertrophy in many species, from rodents to humans, although its mechanisms of action are incompletely understood. Transcript profiling of hearts from a genetic model of cardiac hypertrophy revealed dramatic upregulation of myostatin, not previously recognized to play a role in the heart. Here we show that myostatin abrogates the cardiomyocyte growth response to phenylephrine in vitro through inhibition of p38 and the serine-threonine kinase Akt, a critical determinant of cell size in many species from drosophila to mammals. Evaluation of male myostatin-null mice revealed that their cardiomyocytes and hearts overall were slightly smaller at baseline than littermate controls but exhibited more exuberant growth in response to chronic phenylephrine infusion. The increased cardiac growth in myostatin-null mice corresponded with increased p38 phosphorylation and Akt activation in vivo after phenylephrine treatment. Together, these data demonstrate that myostatin is dynamically regulated in the heart and acts more broadly than previously appreciated to regulate growth of multiple types of striated muscle.

  8. Maternal marginal iodine deficiency limits dendritic growth of cerebellar purkinje cells in rat offspring by NF-κB signaling and MAP1B.

    PubMed

    Yu, Ye; Dong, Jing; Wang, Yuan; Wang, Yi; Min, Hui; Shan, Zhongyan; Teng, Weiping; Chen, Jie

    2017-04-01

    Iodine deficiency (ID) during early pregnancy had an adverse effect on children's psychomotor and motor function. It is worth noting that maternal marginal ID tends to be a common public health problem. Whether marginal ID potentially had adverse effects on the development of cerebellum and the underlying mechanisms remain unclear. Therefore, our aim was to study the effects of marginal ID on the dendritic growth in filial cerebellar Purkinje cells (PCs) and the underlying mechanism. In the present study, we established Wistar rat models by feeding dam rats with a diet deficient in iodine and deionized water supplemented with potassium iodide. We examined the total dendritic length using immunofluorescence, and Western blot analysis was conducted to investigate the activity of nuclear factor-κB (NF-κB) signaling and microtubule-associated protein 1B (MAP1B). Our results showed that marginal ID reduced the total dendritic length of cerebellar PCs, slightly down-regulated the activity of NF-κB signaling and decreased MAP1B in cerebellar PCs on postnatal day (PN) 7, PN14, and PN21. Our study may support the hypothesis that decreased T4 induced by marginal ID limits PCs dendritic growth, which may involve in the disturbance of NF-κB signaling and MAP1B on the cerebellum. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1241-1251, 2017.

  9. CsMAP34, a teleost MAP with dual role: A promoter of MASP-assisted complement activation and a regulator of immune cell activity

    PubMed Central

    Li, Mo-fei; Li, Jun; Sun, Li

    2016-01-01

    In teleost fish, the immune functions of mannan-binding lectin (MBL) associated protein (MAP) and MBL associated serine protease (MASP) are scarcely investigated. In the present study, we examined the biological properties both MAP (CsMAP34) and MASP (CsMASP1) molecules from tongue sole (Cynoglossus semilaevis). We found that CsMAP34 and CsMASP1 expressions occurred in nine different tissues and were upregulated by bacterial challenge. CsMAP34 protein was detected in blood, especially during bacterial infection. Recombinant CsMAP34 (rCsMAP34) bound C. semilaevis MBL (rCsBML) when the latter was activated by bacteria, while recombinant CsMASP1 (rCsMASP1) bound activated rCsBML only in the presence of rCsMAP34. rCsMAP34 stimulated the hemolytic and bactericidal activities of serum complement, whereas anti-CsMAP34 antibody blocked complement activities. Knockdown of CsMASP1 in C. semilaevis resulted in significant inhibition of complement activities. Furthermore, rCsMAP34 interacted directly with peripheral blood leukocytes (PBL) and enhanced the respiratory burst, acid phosphatase activity, chemotactic activity, and gene expression of PBL. These results indicate for the first time that a teleost MAP acts one hand as a regulator that promotes the lectin pathway of complement activation via its ability to recruit MBL to MASP, and other hand as a modulator of immune cell activity. PMID:28008939

  10. 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.

  11. 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

  12. Regulation of Ras signaling and function by plasma membrane microdomains.

    PubMed

    Goldfinger, Lawrence E; Michael, James V

    2017-02-07

    Together H-, N- and KRAS mutations are major contributors to ~30% of all human cancers. Thus, Ras inhibition remains an important anti-cancer strategy. The molecular mechanisms of isotypic Ras oncogenesis are still not completely understood. Monopharmacological therapeutics have not been successful in the clinic. These disappointing outcomes have led to attempts to target elements downstream of Ras, mainly targeting either the Phosphatidylinositol 3-Kinase (PI3K) or Mitogen-Activated Protein Kinase (MAPK) pathways. While several such approaches are moderately effective, recent efforts have focused on preclinical evaluation of combination therapies to improve efficacies. This review will detail current understanding of the contributions of plasma membrane microdomain targeting of Ras to mitogenic and tumorigenic signaling and tumor progression. Moreover, this review will outline novel approaches to target Ras in cancers, including targeting schemes for new drug development, as well as putative re-purposing of drugs in current use to take advantage of blunting Ras signaling by interfering with Ras plasma membrane microdomain targeting and retention.

  13. 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

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

    PubMed Central

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

    2016-01-01

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

  15. Regulation of NB-LRR-type UNI and its related signaling pathway: signaling crosstalk and methodology for quick identification of related factors.

    PubMed

    Uchida, Naoyuki; Tasaka, Masao

    2011-08-01

    Activation of NB-LRR-related UNI proteins by uni-1D mutation, a gain-of-function mutation of the UNI gene, induces some pathogenesis-related responses and also affects morphology through modulation of meristem activities. In a recent study we reported that the uni-1D phenotypes require cooperative action of ERECTA (ER) receptor kinase family members in UNI-expressing cells, suggesting that an intracellular signaling crosstalk between ER-family-dependent and UNI-triggered signaling pathways plays a significant role in the phenotypes. Further we recently succeeded in the establishment of a methodology for rapid identification of factors involved in the UNI function. EMS-induced causal mutations that suppress the uni-1D phenotypes could be identified using whole-genome-sequencing technologies with much less labor compared with the conventional map-based cloning method that is generally time-consuming and labor-intensive. Thus it would be now possible to intensively identify factors that play significant roles in regulation of UNI proteins and/or UNI-related signaling pathways. 

  16. 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.

  17. Differential regulation of Gli proteins by Sufu in the lung affects PDGF signaling and myofibroblast development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mammalian Hedgehog (Hh) signaling relies on three Gli transcription factors to mediate Hh responses. This process is controlled in part by a major negative regulator, Sufu, through its effects on Gli protein level, distribution and activity. In this report, we showed that Sufu regulates Gli1 protein...

  18. Role of IKK-alpha in the EGFR Signaling Regulation

    DTIC Science & Technology

    2014-09-01

    2002) (Huber et al., 2005). To date, several transcriptional repressors, such as Zeb-1/2, Twist1, and Snail -1/2, are known to be involved in EMT...nature of AKT1 in the EMT, we asked whether AKT1 represses EMT via the regulation of EMT mediators, such as Twist1, FOXC2, E12, and Snail . To do this...we transiently transfected HEK-293T cells with HA-myr-AKT1 together with Flag-Twist1, Flag- Snail , Flag-FOXC2, or Flag-E12 and investigated the

  19. 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.

  20. 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.

  1. 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

  2. [COX-2 regulation of prostaglandins in synaptic signaling].

    PubMed

    Yang, Hong-Wei

    2009-10-01

    Cyclooxygenase-2 (COX-2) is a rate-limiting enzyme converting arachidonic acid to prostaglandins (PGs), which is a key messenger in traumatic brain injury- and ischemia-induced neuronal damage and in neuroinflammation. COX-2 is implicated in the pathogeneses of neurodegenerative diseases. Growing evidence implies that the contribution of COX-2 to neuropathology is associated with its involvement in synaptic alteration. Elevation or inhibition of COX-2 has been shown to enhance or suppress excitatory glutamatergic neurotransmission and long-term potentiation (LTP). These events are mainly mediated via PGE2, the predominant reaction product of COX-2, and the PGE2 subtype 2 receptor (EP2). Thus, elucidation of COX-2 in synaptic signaling may provide a mechanistic basis for designing new drugs aimed at preventing, treating or alleviating neuroinflammation-associated neurological disorders.

  3. Signaling pathways regulating cartilage growth plate formation and activity.

    PubMed

    Samsa, William E; Zhou, Xin; Zhou, Guang

    2017-02-01

    The growth plate is a highly specialized and dynamic cartilage structure that serves many essential functions in skeleton patterning, growth and endochondral ossification in developing vertebrates. Major signaling pathways initiated by classical morphogens and by other systemic and tissue-specific factors are intimately involved in key aspects of growth plate development. As a corollary of these essential functions, disturbances in these pathways due to mutations or environmental factors lead to severe skeleton disorders. Here, we review these pathways and the most recent progress made in understanding their roles in chondrocyte differentiation in growth plate development and activity. Furthermore, we discuss newly uncovered pathways involved in growth plate formation, including mTOR, the circadian clock, and the COP9 signalosome.

  4. ROS1 signaling regulates epithelial differentiation in the epididymis.

    PubMed

    Jun, Hyun Jung; Roy, Jeremy; Smith, Tegan B; Wood, Levi B; Lane, Keara; Woolfenden, Steve; Punko, Diana; Bronson, Roderick T; Haigis, Kevin M; Breton, Sylvie; Charest, Al

    2014-09-01

    The initial segment (IS) of the epididymis plays an essential role in male fertility. The IS epithelium is undifferentiated and nonfunctional at birth. Prior to puberty, the epithelium undergoes differentiation that leads to the formation of a fully functional organ. However, the mechanistic details of this program are not well understood. To explore this further, we used genetic engineering to create a kinase dead allele of the ROS1 receptor tyrosine kinase in mice and studied the effects of ROS1 tyrosine kinase activity on the differentiation of the IS epithelium. We show that the expression and activation of ROS1 coincides with the onset of differentiation and is exclusively located in the IS of the maturing and adult mouse epididymides. Here we demonstrate that the differentiation of the IS is dependent on the kinase activity of ROS1 and its downstream effector MEK1/2-ERK1/2 signaling axis. Using genetic engineering, we show that germ line ablation of ROS1 kinase activity leads to a failure of the IS epithelium to differentiate, and as a consequence sperm maturation and infertility were dramatically perturbed. Pharmacological inhibition of ROS1 kinase activity in the developing epididymis, however, only delayed differentiation transiently and did not result in infertility. Our results demonstrate that ROS1 kinase activity and the ensuing MEK1/2-ERK1/2 signaling are necessary for the postnatal development of the IS epithelium and that a sustained ablation of ROS1 kinase activity within the critical window of terminal differentiation abrogate the function of the epididymis and leads to sterility.

  5. ROS1 Signaling Regulates Epithelial Differentiation in the Epididymis

    PubMed Central

    Jun, Hyun Jung; Roy, Jeremy; Smith, Tegan B.; Wood, Levi B.; Lane, Keara; Woolfenden, Steve; Punko, Diana; Bronson, Roderick T.; Haigis, Kevin M.; Breton, Sylvie

    2014-01-01

    The initial segment (IS) of the epididymis plays an essential role in male fertility. The IS epithelium is undifferentiated and nonfunctional at birth. Prior to puberty, the epithelium undergoes differentiation that leads to the formation of a fully functional organ. However, the mechanistic details of this program are not well understood. To explore this further, we used genetic engineering to create a kinase dead allele of the ROS1 receptor tyrosine kinase in mice and studied the effects of ROS1 tyrosine kinase activity on the differentiation of the IS epithelium. We show that the expression and activation of ROS1 coincides with the onset of differentiation and is exclusively located in the IS of the maturing and adult mouse epididymides. Here we demonstrate that the differentiation of the IS is dependent on the kinase activity of ROS1 and its downstream effector MEK1/2-ERK1/2 signaling axis. Using genetic engineering, we show that germ line ablation of ROS1 kinase activity leads to a failure of the IS epithelium to differentiate, and as a consequence sperm maturation and infertility were dramatically perturbed. Pharmacological inhibition of ROS1 kinase activity in the developing epididymis, however, only delayed differentiation transiently and did not result in infertility. Our results demonstrate that ROS1 kinase activity and the ensuing MEK1/2-ERK1/2 signaling are necessary for the postnatal development of the IS epithelium and that a sustained ablation of ROS1 kinase activity within the critical window of terminal differentiation abrogate the function of the epididymis and leads to sterility. PMID:24971615

  6. 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

  7. Binding of E-MAP-115 to microtubules is regulated by cell cycle- dependent phosphorylation

    PubMed Central

    1995-01-01

    Expression levels of E-MAP-115, a microtubule-associated protein that stabilizes microtubules, increase with epithelial cell polarization and differentiation (Masson and Kreis, 1993). Although polarizing cells contain significant amounts of this protein, they can still divide and thus all stabilized microtubules must disassemble at the onset of mitosis to allow formation of the dynamic mitotic spindle. We show here that binding of E-MAP-115 to microtubules is regulated by phosphorylation during the cell cycle. Immunolabeling of HeLa cells for E-MAP-115 indicates that the protein is absent from microtubules during early prophase and progressively reassociates with microtubules after late prophase. A fraction of E-MAP-115 from HeLa cells released from a block at the G1/S boundary runs with higher apparent molecular weight on SDS-PAGE, with a peak correlating with the maximal number of cells in early stages of mitosis. E-MAP-115 from nocodazole-arrested mitotic cells, which can be obtained in larger amounts, displays identical modifications and was used for further biochemical characterization. The level of incorporation of 32P into mitotic E-MAP-115 is about 15- fold higher than into the interphase protein. Specific threonine phosphorylation occurs in mitosis, and the amount of phosphate associated with serine also increases. Hyperphosphorylated E-MAP-115 from mitotic cells cannot bind stably to microtubules in vitro. These results suggest that phosphorylation of E-MAP-115 is a prerequisite for increasing the dynamic properties of the interphase microtubules which leads to the assembly of the mitotic spindle at the onset of mitosis. Microtubule-associated proteins are thus most likely key targets for kinases which control changes in microtubule dynamic properties at the G2- to M-phase transition. PMID:7490279

  8. 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.

  9. Regulators and effectors of bone morphogenetic protein signalling in the cardiovascular system

    PubMed Central

    Luo, Jiang-Yun; Zhang, Yang; Wang, Li; Huang, Yu

    2015-01-01

    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

  10. Regulation of cytokine signaling by the SOCS and Spred family proteins.

    PubMed

    Yoshimura, Akihiko

    2009-06-01

    Various cytokines are involved in the regulation of the immune system and of hematopoiesis. Most cytokines utilize the so-called JAK-STAT pathway, but others activate the Ras-ERK pathway, which is more important than the STAT pathway for the proliferation of hematopoietic cells. Dysregulation of cytokine signaling can cause a variety of diseases, including allergy, inflammation, and cancer. We have identified two important regulator families involved in cytokine signaling: the SOCS proteins and the Spred proteins. Suppressors of cytokine signaling (SOCS) proteins bind to JAK and to certain receptors, thereby suppressing further signaling events. Spred family proteins interact with Ras and Raf, thereby suppressing ERK activation. Studies have shown that SOCS and Spred proteins are key physiological regulators of immunity, hematopoiesis, and angiogenesis. Evidence is also emerging for the involvement of these proteins in human diseases.

  11. 5-HT1A receptor-mediated phosphorylation of extracellular signal-regulated kinases (ERK1/2) is modulated by regulator of G protein signaling protein 19.

    PubMed

    Wang, Qin; Terauchi, Akiko; Yee, Christopher H; Umemori, Hisashi; Traynor, John R

    2014-09-01

    The 5-HT1A receptor is a G protein coupled receptor (GPCR) that activates G proteins of the Gαi/o family. 5-HT1A receptors expressed in the raphe, hippocampus and prefrontal cortex are implicated in the control of mood and are targets for anti-depressant drugs. Regulators of G protein signaling (RGS) proteins are members of a large family that play important roles in signal transduction downstream of G protein coupled receptors (GPCRs). The main role of RGS proteins is to act as GTPase accelerating proteins (GAPs) to dampen or negatively regulate GPCR-mediated signaling. We have shown that a mouse expressing Gαi2 that is insensitive to all RGS protein GAP activity has an anti-depressant-like phenotype due to increased signaling of postsynaptic 5-HT1A receptors, thus implicating the 5-HT1A receptor-Gαi2 complex as an important target. Here we confirm that RGS proteins act as GAPs to regulate signaling to adenylate cyclase and the mitogen-activated protein kinase (MAPK) pathway downstream of the 5-HT1A receptor, using RGS-insensitive Gαi2 protein expressed in C6 cells. We go on to use short hairpin RNA (shRNA) to show that RGS19 is responsible for the GAP activity in C6 cells and also that RGS19 acts as a GAP for 5-HT1A receptor signaling in human neuroblastoma SH-SY5Y cells and primary hippocampal neurons. In addition, in both cell types the synergy between 5-HT1A receptor and the fibroblast growth factor receptor 1 in stimulating the MAPK pathway is enhanced following shRNA reduction of RGS19 expression. Thus RGS19 may be a viable new target for anti-depressant medications.

  12. Regulation of Drosophila Brain Wiring by Neuropil Interactions via a Slit-Robo-RPTP Signaling Complex.

    PubMed

    Oliva, Carlos; Soldano, Alessia; Mora, Natalia; De Geest, Natalie; Claeys, Annelies; Erfurth, Maria-Luise; Sierralta, Jimena; Ramaekers, Ariane; Dascenco, Dan; Ejsmont, Radoslaw K; Schmucker, Dietmar; Sanchez-Soriano, Natalia; Hassan, Bassem A

    2016-10-24

    The axonal wiring molecule Slit and its Round-About (Robo) receptors are conserved regulators of nerve cord patterning. Robo receptors also contribute to wiring brain circuits. Whether molecular mechanisms regulating these signals are modified to fit more complex brain wiring processes is unclear. We investigated the role of Slit and Robo receptors in wiring Drosophila higher-order brain circuits and identified differences in the cellular and molecular mechanisms of Robo/Slit function. First, we find that signaling by Robo receptors in the brain is regulated by the Receptor Protein Tyrosine Phosphatase RPTP69d. RPTP69d increases membrane availability of Robo3 without affecting its phosphorylation state. Second, we detect no midline localization of Slit during brain development. Instead, Slit is enriched in the mushroom body, a neuronal structure covering large areas of the brain. Thus, a divergent molecular mechanism regulates neuronal circuit wiring in the Drosophila brain, partly in response to signals from the mushroom body.

  13. PROBING THE DARK FLOW SIGNAL IN WMAP 9 -YEAR AND PLANCK COSMIC MICROWAVE BACKGROUND MAPS

    SciTech Connect

    Atrio-Barandela, F.; Kashlinsky, A.; Ebeling, H.; Fixsen, D. J.; Kocevski, D. E-mail: Alexander.Kashlinsky@nasa.gov E-mail: Dale.Fixsen@nasa.gov

    2015-09-10

    The “dark flow” dipole is a statistically significant dipole found at the position of galaxy clusters in filtered maps of Cosmic Microwave Background (CMB) temperature anisotropies. The dipole measured in WMAP 3-, 5-, and 7- year data releases was (1) mutually consistent, (2) roughly aligned with the all-sky CMB dipole, and (3) correlated with clusters’ X-ray luminosities. We analyzed WMAP 9 -year and Planck 1st- year data releases using a catalog of 980 clusters outside of the Kp0 mask to test our earlier findings. The dipoles measured on these new data sets are fully compatible with our earlier estimates, are similar in amplitude and direction to our previous results, and are in disagreement with the results of an earlier study by the Planck Collaboration. Furthermore, in the Planck data sets dipoles are found to be independent of frequency, ruling out the thermal Sunyaev–Zeldovich as the source of the effect. In the data of both WMAP and Planck we find a clear correlation between the dipole measured at the cluster location in filtered maps and the average anisotropy on the original maps, further proving that the dipole is associated with clusters. The dipole signal is dominated by the most massive clusters, with a statistical significance that is better than 99%, slightly larger than in WMAP. Since both data sets differ in foreground contributions, instrumental noise, and other systematics, the agreement between the WMAP and Planck dipoles argues against them being due to systematic effects in either of the experiments.

  14. 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).

  15. 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

  16. 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

  17. Regulation of the BMP Signaling-Responsive Transcriptional Network in the Drosophila Embryo.

    PubMed

    Deignan, Lisa; Pinheiro, Marco T; Sutcliffe, Catherine; Saunders, Abbie; Wilcockson, Scott G; Zeef, Leo A H; Donaldson, Ian J; Ashe, Hilary L

    2016-07-01

    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.

  18. Autophagy is involved in mouse kidney development and podocyte differentiation regulated by Notch signalling.

    PubMed

    Zhang, Chuyue; Li, Wen; Wen, Junkai; Yang, Zhuo

    2017-02-03

    Podocyte dysfunction results in glomerular diseases accounted for 90% of end-stage kidney disease. The evolutionarily conserved Notch signalling makes a crucial contribution in podocyte development and function. However, the underlying mechanism of Notch pathway modulating podocyte differentiation remains less obvious. Autophagy, reported to be related with Notch signalling pathways in different animal models, is regarded as a possible participant during podocyte differentiation. Here, we found the dynamic changes of Notch1 were coincided with autophagy: they both increased during kidney development and podocyte differentiation. Intriguingly, when Notch signalling was down-regulated by DAPT, autophagy was greatly diminished, and differentiation was also impaired. Further, to better understand the relationship between Notch signalling and autophagy in podocyte differentiation, rapamycin was added to enhance autophagy levels in DAPT-treated cells, and as a result, nephrin was recovered and DAPT-induced injury was ameliorated. Therefore, we put forward that autophagy is involved in kidney development and podocyte differentiation regulated by Notch signalling.

  19. The molecular machinery regulating apoptosis signal transduction and its implication in human physiology and pathophysiologies.

    PubMed

    Hellwig, C T; Passante, E; Rehm, M

    2011-02-01

    The regulation of apoptotic cell death, a terminal and fatal cell fate decision, has been intensely investigated and, due to its paramount implications for human health and disease, has sparked one of the most prolific and competitive research fields in biological and biomedical sciences of the past decades. Many key components of the molecular machinery processing and transducing apoptotic cell death signals have been described in great detail by now, dramatically advancing our understanding of how the network of apoptosis signaling proteins integrates and regulates cell death signals, and ultimately executes apoptosis. Building on the latest significant advances in deciphering apoptosis signal transduction as well as on the central original groundbreaking discoveries in cell death research, we here present an in-depth description of the current knowledge on the core molecular machinery of apoptotic signaling and how it is implicated in human physiology and pathophysiologies.

  20. 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

  1. 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

  2. Activity dependent mechanisms of visual map formation--from retinal waves to molecular regulators.

    PubMed

    Assali, Ahlem; Gaspar, Patricia; Rebsam, Alexandra

    2014-11-01

    The refinement of neural connections requires activity-dependent mechanisms in addition to the genetic program initially establishing wiring diagrams. The well-understood organization of the visual system makes it an accessible model for analyzing the contribution of activity in the formation of connectivity. Prior to visual experience, patterned spontaneous activity in the form of retinal waves has an important role for the establishment of eye-specific and retinotopic maps by acting on the refinement of axon arborization. In the present review, which focuses on experimental data obtained in mice and ferrets, we highlight the features of retinal activity that are important for visual map formation and question whether synaptic release and Hebbian based competition rules apply to this system. Recent evidence using genetic tools that allowed the manipulation of different features of neural activity have clarified the controversy on whether activity is instructive or permissive for visual map formation. Furthermore, current evidence strongly suggests that different mechanisms are at play for different types of axons (ipsilateral vs. contralateral), maps (eye-specific vs. retinotopic) or targets. Many molecules that either modulate activity or are modulated by activity are important in the formation of the visual map, such as adenylate cyclase 1, serotonin, or molecules from the immune system. Finally, new players in the game include retrograde messengers signaling from the target cell to the retinal axons as well as microglia that could help to eliminate inappropriate synapses.

  3. 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.

  4. P(II) signal transduction proteins: nitrogen regulation and beyond.

    PubMed

    Huergo, Luciano F; Chandra, Govind; Merrick, Mike

    2013-03-01

    The P(II) proteins are one of the most widely distributed families of signal transduction proteins in nature. They are pivotal players in the control of nitrogen metabolism in bacteria and archaea, and are also found in the plastids of plants. Quite remarkably, P(II) proteins control the activities of a diverse range of enzymes, transcription factors and membrane transport proteins, and in recent years the extent of these interactions has been recognized to be much greater than heretofore described. Major advances have been made in structural studies of P(II) proteins, including the solution of the first structures of P(II) proteins complexed with their targets. We have also begun to gain insights into how the key effector molecules, 2-oxoglutarate and ATP/ADP, influence the activities of P(II) proteins. In this review, we have set out to summarize our current understanding of P(II) biology and to consider where future studies of these extraordinarily adaptable proteins might lead us.

  5. Surface microcracks signal osteoblasts to regulate alignment and bone formation

    PubMed Central

    Shu, Yutian; Baumann, Melissa J.; Case, Eldon D.; Irwin, Regina K.; Meyer, Sarah E.; Pearson, Craig S.; McCabe, Laura R.

    2014-01-01

    Microcracks are present in bone and can result from fatigue damage due to repeated, cyclically applied stresses. From a mechanical point, microcracks can dissipate strain energy at the advancing tip of a crack to improve overall bone toughness. Physiologically, microcracks are thought to trigger bone remodeling. Here, we examine the effect of microcracks specifically on osteoblasts, which are bone-forming cells, by comparing cell responses on microcracked versus non-microcracked hydroxyapatite (HA) specimens. Osteoblast attachment was found to be greater on microcracked HA specimens (p<0.05). More importantly, we identified the preferential alignment of osteoblasts in the direction of the microcracks on HA. Cells also displayed a preferential attachment that was 75 to 90 μm away from the microcrack indent. After 21 days of culture, osteoblast maturation was notably enhanced on the HA with microcracks, as indicated by increased alkaline phosphatase activity and gene expression. Furthermore, examination of bone deposition by confocal laser scanning microscope indicated preferential mineralization at microcrack indentation sites. Dissolution studies indicate that the microcracks increase calcium release, which could contribute to osteoblast responses. Our findings suggest that microcracks signal osteoblast attachment and bone formation/healing. PMID:25280696

  6. 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

  7. 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.

  8. TRIM protein-mediated regulation of inflammatory and innate immune signaling and its association with antiretroviral activity.

    PubMed

    Uchil, Pradeep D; Hinz, Angelika; Siegel, Steven; Coenen-Stass, Anna; Pertel, Thomas; Luban, Jeremy; Mothes, Walther

    2013-01-01

    Members of the tripartite interaction motif (TRIM) family of E3 ligases are emerging as critical regulators of innate immunity. To identify new regulators, we carried out a screen of 43 human TRIM proteins for the ability to activate NF-κB, AP-1, and interferon, hallmarks of many innate immune signaling pathways. We identified 16 TRIM proteins that induced NF-κB and/or AP-1. We found that one of these, TRIM62, functions in the TRIF branch of the TLR4 signaling pathway. Knockdown of TRIM62 in primary macrophages led to a defect in TRIF-mediated late NF-κB, AP-1, and interferon production after lipopolysaccharide challenge. We also discovered a role for TRIM15 in the RIG-I-mediated interferon pathway upstream of MAVS. Knockdown of TRIM15 limited virus/RIG-I ligand-induced interferon production and enhanced vesicular stomatitis virus replication. In addition, most TRIM proteins previously identified to inhibit murine leukemia virus (MLV) demonstrated an ability to induce NF-κB/AP-1. Interfering with the NF-κB and AP-1 signaling induced by the antiretroviral TRIM1 and TRIM62 proteins rescued MLV release. In contrast, human immunodeficiency virus type 1 (HIV-1) gene expression was increased by TRIM proteins that induce NF-κB. HIV-1 resistance to inflammatory TRIM proteins mapped to the NF-κB sites in the HIV-1 long terminal repeat (LTR) U3 and could be transferred to MLV. Thus, our work identifies new TRIM proteins involved in innate immune signaling and reinforces the striking ability of HIV-1 to exploit innate immune signaling for the purpose of viral replication.

  9. 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

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

    PubMed Central

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

    2010-01-01

    G-protein heterotrimers, composed of a guanine nucleotide-binding Gα subunit and an obligate Gβγ dimer, regulate signal transduction pathways by cycling between GDP- and GTP-bound states. Signal deactivation is achieved by Gα-mediated GTP hydrolysis (GTPase activity) which is enhanced by the GTPase-accelerating protein (GAP) activity of “regulator of G-protein signaling” (RGS) proteins. In a cellular context, RGS proteins have also been shown to speed up the onset of signaling, and to accelerate deactivation without changing amplitude or sensitivity of the signal. This latter paradoxical activity has been variably attributed to GAP/enzymatic or non-GAP/scaffolding functions of these proteins. Here, we validated and exploited a Gα switch-region point mutation, known to engender increased GTPase activity, to mimic in cis the GAP function of RGS proteins. While the transition-state, GDP·AlF4 −-bound conformation of the G202A mutant was found to be nearly identical to wild-type, Gαi1(G202A)·GDP assumed a divergent conformation more closely resembling the GDP·AlF4 −-bound state. When placed within Saccharomyces cerevisiae Gα subunit Gpa1, the fast-hydrolysis mutation restored appropriate dose–response behaviors to pheromone signaling in the absence of RGS-mediated GAP activity. A bioluminescence resonance energy transfer (BRET) readout of heterotrimer activation with high temporal resolution revealed that fast intrinsic GTPase activity could recapitulate in cis the kinetic sharpening (increased onset and deactivation rates) and blunting of sensitivity also engendered by RGS protein action in trans. Thus Gα-directed GAP activity, the first biochemical function ascribed to RGS proteins, is sufficient to explain the activation kinetics and agonist sensitivity observed from G-protein–coupled receptor (GPCR) signaling in a cellular context. PMID:20351284

  11. Role of calcium in regulation of phosphoinositide signaling pathway.

    PubMed

    Patel, J; Keith, R A; Salama, A I; Moore, W C

    1991-01-01

    Using primary neuronal cultures we have examined the role of extracellular Ca2+ in a receptor-regulated phosphoinositide turnover. We report that receptor (glutamic acid and acetylcholine)-activated phosphoinositide turnover requires the presence of extracellular Ca2+ (EC50 = 21.1 microM). The requirement for Ca2+ appears to be at an intracellular level and is highly selective for Ca2+. We also found that several inorganic and organic Ca2+ channel blockers, including La3+ and verapamil, inhibit phosphoinositide turnover. However, the pharmacological profile of these agents in this regard was distinct from their actions at the voltage-sensitive Ca2+ channels. To explain the above requirement for extracellular Ca2+ in agonist-stimulated phosphoinositide turnover and its sensitivity to Ca(2+)-channel blockers, we propose a hypothetical model suggesting that Ca2+, following IP-3-mediated mobilization, exerts a facilitatory action on the activity of receptor-phospholipase C complex. We further propose that in the absence of extracellular Ca2+ or in the presence of certain Ca(2+)-channel blockers, refilling of calciosomes is ineffectual or inhibited, causing its depletion and subsequent inactivation of agonist-stimulated phosphoinositide turnover.

  12. Oxygen-dependent Regulation of Erythropoietin Receptor Turnover and Signaling*

    PubMed Central

    Heir, Pardeep; Srikumar, Tharan; Bikopoulos, George; Bunda, Severa; Poon, Betty P.; Lee, Jeffrey E.; Raught, Brian; Ohh, Michael

    2016-01-01

    von Hippel-Lindau (VHL) disease is a rare familial cancer predisposition syndrome caused by a loss or mutation in a single gene, VHL, but it exhibits a wide phenotypic variability that can be categorized into distinct subtypes. The phenotypic variability has been largely argued to be attributable to the extent of deregulation of the α subunit of hypoxia-inducible factor α, a well established target of VHL E3 ubiquitin ligase, ECV (Elongins/Cul2/VHL). Here, we show that erythropoietin receptor (EPOR) is hydroxylated on proline 419 and 426 via prolyl hydroxylase 3. EPOR hydroxylation is required for binding to the β domain of VHL and polyubiquitylation via ECV, leading to increased EPOR turnover. In addition, several type-specific VHL disease-causing mutants, including those that have retained proper binding and regulation of hypoxia-inducible factor α, showed a severe defect in binding prolyl hydroxylated EPOR peptides. These results identify EPOR as the second bona fide hydroxylation-dependent substrate of VHL that potentially influences oxygen homeostasis and contributes to the complex genotype-phenotype correlation in VHL disease. PMID:26846855

  13. Purinergic Signaling as a Regulator of Th17 Cell Plasticity.

    PubMed

    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.

  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. 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.

  16. 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.

  17. Electrical signals as mechanism of photosynthesis regulation in plants.

    PubMed

    Sukhov, Vladimir

    2016-12-01

    This review summarizes current works concerning the effects of electrical signals (ESs) on photosynthesis, the mechanisms of the effects, and its physiological role in plants. Local irritations of plants induce various photosynthetic responses in intact leaves, including fast and long-term inactivation of photosynthesis, and its activation. Irritation-induced ESs, including action potential, variation potential, and system potential, probably causes the photosynthetic responses in intact leaves. Probable mechanisms of induction of fast inactivation of photosynthesis are associated with Ca(2+)- and (or) H(+)-influxes during ESs generation; long-term inactivation of photosynthesis might be caused by Ca(2+)- and (or) H(+)-influxes, production of abscisic and jasmonic acids, and inactivation of phloem H(+)-sucrose symporters. It is probable that subsequent development of inactivation of photosynthesis is mainly associated with decreased CO2 influx and inactivation of the photosynthetic dark reactions, which induces decreased photochemical quantum yields of photosystems I and II and increased non-photochemical quenching of photosystem II fluorescence and cyclic electron flow around photosystem I. However, other pathways of the ESs influence on the photosynthetic light reactions are also possible. One of them might be associated with ES-connected acidification of chloroplast stroma inducing ferredoxin-NADP(+) reductase accumulation at the thylakoids in Tic62 and TROL complexes. Mechanisms of ES-induced activation of photosynthesis require further investigation. The probable ultimate effect of ES-induced photosynthetic responses in plant life is the increased photosynthetic machinery resistance to stressors, including high and low temperatures, and enhanced whole-plant resistance to environmental factors at least during 1 h after irritation.

  18. 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

    2011-06-07

    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.

  19. Regulation of angiogenesis via Notch signaling in breast cancer and cancer stem cells.

    PubMed

    Zhou, Weiqiang; Wang, Guangdi; Guo, Shanchun

    2013-12-01

    Breast cancer angiogenesis is elicited and regulated by a number of factors including the Notch signaling. Notch receptors and ligands are expressed in breast cancer cells as well as in the stromal compartment and have been implicated in carcinogenesis. Signals exchanged between neighboring cells through the Notch pathway can amplify and consolidate molecular differences, which eventually dictate cell fates. Notch signaling and its crosstalk with many signaling pathways play an important role in breast cancer cell growth, migration, invasion, metastasis and angiogenesis, as well as cancer stem cell (CSC) self-renewal. Therefore, significant attention has been paid in recent years toward the development of clinically useful antagonists of Notch signaling. Better understanding of the structure, function and regulation of Notch intracellular signaling pathways, as well as its complex crosstalk with other oncogenic signals in breast cancer cells will be essential to ensure rational design and application of new combinatory therapeutic strategies. Novel opportunities have emerged from the discovery of Notch crosstalk with inflammatory and angiogenic cytokines and their links to CSCs. Combinatory treatments with drugs designed to prevent Notch oncogenic signal crosstalk may be advantageous over λ secretase inhibitors (GSIs) alone. In this review, we focus on the more recent advancements in our knowledge of aberrant Notch signaling contributing to breast cancer angiogenesis, as well as its crosstalk with other factors contributing to angiogenesis and CSCs.

  20. 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

  1. Histamine H3 Receptor Regulates Sensorimotor Gating and Dopaminergic Signaling in the Striatum.

    PubMed

    Kononoff Vanhanen, Jenni; Nuutinen, Saara; Tuominen, Mervi; Panula, Pertti

    2016-05-01

    The brain histamine system has been implicated in regulation of sensorimotor gating deficits and in Gilles de la Tourette syndrome. Histamine also regulates alcohol reward and consumption via H3 receptor (H3R), possibly through an interaction with the brain dopaminergic system. Here, we identified the histaminergic mechanism of sensorimotor gating and the role of histamine H3R in the regulation of dopaminergic signaling. We found that H3R knockout mice displayed impaired prepulse inhibition (PPI), indicating deficiency in sensorimotor gating. Histamine H1 receptor knockout and histidine decarboxylase knockout mice had similar PPI as their controls. Dopaminergic drugs increased PPI of H3R knockout mice to the same level as in control mice, suggesting that changes in dopamine receptors might underlie deficient PPI response when H3R is lacking. Striatal dopamine D1 receptor mRNA level was lower, and D1 and D2 receptor-mediated activation of extracellular signal-regulated kinase 1/2 was absent in the striatum of H3R knockout mice, suggesting that H3R is essential for the dopamine receptor-mediated signaling. In conclusion, these findings demonstrate that H3R is an important regulator of sensorimotor gating, and the lack of H3R significantly modifies striatal dopaminergic signaling. These data support the usefulness of H3R ligands in neuropsychiatric disorders with preattentional deficits and disturbances in dopaminergic signaling.

  2. Predicting the intensity mapping signal for multi-J CO lines

    SciTech Connect

    Mashian, Natalie; Loeb, Abraham; Sternberg, Amiel E-mail: amiel@wise.tau.ac.il

    2015-11-01

    We present a novel approach to estimating the intensity mapping signal of any CO rotational line emitted during the Epoch of Reionization (EoR). Our approach is based on large velocity gradient (LVG) modeling, a radiative transfer modeling technique that generates the full CO spectral line energy distribution (SLED) for a specified gas kinetic temperature, volume density, velocity gradient, molecular abundance, and column density. These parameters, which drive the physics of CO transitions and ultimately dictate the shape and amplitude of the CO SLED, can be linked to the global properties of the host galaxy, mainly the star formation rate (SFR) and the SFR surface density. By further employing an empirically derived SFR−M relation for high redshift galaxies, we can express the LVG parameters, and thus the specific intensity of any CO rotational transition, as functions of the host halo mass M and redshift z. Integrating over the range of halo masses expected to host CO-luminous galaxies, we predict a mean CO(1-0) brightness temperature ranging from ∼ 0.6 μK at z = 6 to ∼ 0.03 μK at z = 10 with brightness temperature fluctuations of Δ{sub CO}{sup 2} ∼ 0.1 and 0.005 μK respectively, at k = 0.1 Mpc{sup −1}. In this model, the CO emission signal remains strong for higher rotational levels at z = 6, with ( T{sub CO} ) ∼ 0.3 and 0.05 μK for the CO J = 6arrow5 and CO J = 10arrow9 transitions respectively. Including the effects of CO photodissociation in these molecular clouds, especially at low metallicities, results in the overall reduction in the amplitude of the CO signal, with the low- and high-J lines weakening by 2–20% and 10–45%, respectively, over the redshift range 4 < z < 10.

  3. 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.

  4. Drosophila spichthyin inhibits BMP signaling and regulates synaptic growth and axonal microtubules

    PubMed Central

    Wang, Xinnan; Shaw, W. Robert; Tsang, Hilda T. H.; Reid, Evan; O'Kane, Cahir J.

    2008-01-01

    Summary To understand the functions of SPG6, mutated in the neurodegenerative disease hereditary spastic paraplegia, and of ichthyin, mutated in autosomal recessive congenital ichthyosis, we have studied their Drosophila ortholog, spichthyin (Spict). Spict is found on early endosomes. Loss of Spict leads to upregulation of BMP signaling and expansion of the neuromuscular junction. BMP signaling is also necessary for a normal microtubule cytoskeleton and axonal transport; analysis of loss and gain-of-function phenotypes suggests that Spict antagonizes this function of BMP signaling. Spict interacts with BMP receptors and promotes their internalization from the plasma membrane, suggesting that it inhibits BMP signaling by regulating BMP receptor traffic. This is the first demonstration of a role for an SPG protein or ichthyin family member in a specific signaling pathway, and suggests disease mechanisms for hereditary spastic paraplegia that involve dependence of the microtubule cytoskeleton on BMP signaling. PMID:17220882

  5. Drosophila spichthyin inhibits BMP signaling and regulates synaptic growth and axonal microtubules.

    PubMed

    Wang, Xinnan; Shaw, W Robert; Tsang, Hilda T H; Reid, Evan; O'Kane, Cahir J

    2007-02-01

    To understand the functions of NIPA1, mutated in the neurodegenerative disease hereditary spastic paraplegia, and of ichthyin, mutated in autosomal recessive congenital ichthyosis, we have studied their Drosophila melanogaster ortholog, spichthyin (Spict). Spict is found on early endosomes. Loss of Spict leads to upregulation of bone morphogenetic protein (BMP) signaling and expansion of the neuromuscular junction. BMP signaling is also necessary for a normal microtubule cytoskeleton and axonal transport; analysis of loss- and gain-of-function phenotypes indicate that Spict may antagonize this function of BMP signaling. Spict interacts with BMP receptors and promotes their internalization from the plasma membrane, implying that it inhibits BMP signaling by regulating BMP receptor traffic. This is the first demonstration of a role for a hereditary spastic paraplegia protein or ichthyin family member in a specific signaling pathway, and implies disease mechanisms for hereditary spastic paraplegia that involve dependence of the microtubule cytoskeleton on BMP signaling.

  6. 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

    2015-03-03

    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.

  7. Agrin as a Mechanotransduction Signal Regulating YAP through the Hippo Pathway.

    PubMed

    Chakraborty, Sayan; Njah, Kizito; Pobbati, Ajaybabu V; Lim, Ying Bena; Raju, Anandhkumar; Lakshmanan, Manikandan; Tergaonkar, Vinay; Lim, Chwee Teck; Hong, Wanjin

    2017-03-07

    The Hippo pathway effectors YAP and TAZ act as nuclear sensors of mechanical signals in response to extracellular matrix (ECM) cues. However, the identity and nature of regulators in the ECM and the precise pathways relaying mechanoresponsive signals into intracellular sensors remain unclear. Here, we uncover a functional link between the ECM proteoglycan Agrin and the transcriptional co-activator YAP. Importantly, Agrin transduces matrix and cellular rigidity signals that enhance stability and mechanoactivity of YAP through the integrin-focal adhesion- and Lrp4/MuSK receptor-mediated signaling pathways. Agrin antagonizes focal adhesion assembly of the core Hippo components by facilitating ILK-PAK1 signaling and negating the functions of Merlin and LATS1/2. We further show that Agrin promotes oncogenesis through YAP-dependent transcription and is clinically relevant in human liver cancer. We propose that Agrin acts as a mechanotransduction signal in the ECM.

  8. [Dual-role regulations of canonical Wnt/beta-catenin signaling pathway].

    PubMed

    Liu, Yang; Zhang, Chen-guang; Zhou, Chun-yan

    2010-04-18

    In recent years, Wnt/beta-catenin signaling has been identified as a key player in embryogenesis and human diseases. Canonical Wnt signaling pathway is controlled by a variety of classic molecules like Wnt, beta-catenin, Axin, APC, GSK-3beta and CK1, which interact and coordinate to regulate the expressions of cell signaling molecules. The latest evidences suggest that some components of the Wnt/beta-catenin signaling, like APC, GSK-3beta, CK1, Dkk2 and WISE, play dual roles different from what they have been thought previously. Here we reviewed some recent discoveries on the canonical Wnt/beta-catenin signaling pathway to provide some new ideas and principles for signaling transduction studies.

  9. 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

  10. 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.

  11. 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

  12. 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

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

    PubMed Central

    Aizenman, Elias

    2011-01-01

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

  14. Identification of critical paralog groups with indispensable roles in the regulation of signaling flow

    PubMed Central

    Modos, Dezso; Brooks, Johanne; Fazekas, David; Ari, Eszter; Vellai, Tibor; Csermely, Peter; Korcsmaros, Tamas; Lenti, Katalin

    2016-01-01

    Extensive cross-talk between signaling pathways is required to integrate the myriad of extracellular signal combinations at the cellular level. Gene duplication events may lead to the emergence of novel functions, leaving groups of similar genes - termed paralogs - in the genome. To distinguish critical paralog groups (CPGs) from other paralogs in human signaling networks, we developed a signaling network-based method using cross-talk annotation and tissue-specific signaling flow analysis. 75 CPGs were found with higher degree, betweenness centrality, closeness, and ‘bowtieness’ when compared to other paralogs or other proteins in the signaling network. CPGs had higher diversity in all these measures, with more varied biological functions and more specific post-transcriptional regulation than non-critical paralog groups (non-CPG). Using TGF-beta, Notch and MAPK pathways as examples, SMAD2/3, NOTCH1/2/3 and MEK3/6-p38 CPGs were found to regulate the signaling flow of their respective pathways. Additionally, CPGs showed a higher mutation rate in both inherited diseases and cancer, and were enriched in drug targets. In conclusion, the results revealed two distinct types of paralog groups in the signaling network: CPGs and non-CPGs. Thus highlighting the importance of CPGs as compared to non-CPGs in drug discovery and disease pathogenesis. PMID:27922122

  15. Identification of critical paralog groups with indispensable roles in the regulation of signaling flow.

    PubMed

    Modos, Dezso; Brooks, Johanne; Fazekas, David; Ari, Eszter; Vellai, Tibor; Csermely, Peter; Korcsmaros, Tamas; Lenti, Katalin

    2016-12-06

    Extensive cross-talk between signaling pathways is required to integrate the myriad of extracellular signal combinations at the cellular level. Gene duplication events may lead to the emergence of novel functions, leaving groups of similar genes - termed paralogs - in the genome. To distinguish critical paralog groups (CPGs) from other paralogs in human signaling networks, we developed a signaling network-based method using cross-talk annotation and tissue-specific signaling flow analysis. 75 CPGs were found with higher degree, betweenness centrality, closeness, and 'bowtieness' when compared to other paralogs or other proteins in the signaling network. CPGs had higher diversity in all these measures, with more varied biological functions and more specific post-transcriptional regulation than non-critical paralog groups (non-CPG). Using TGF-beta, Notch and MAPK pathways as examples, SMAD2/3, NOTCH1/2/3 and MEK3/6-p38 CPGs were found to regulate the signaling flow of their respective pathways. Additionally, CPGs showed a higher mutation rate in both inherited diseases and cancer, and were enriched in drug targets. In conclusion, the results revealed two distinct types of paralog groups in the signaling network: CPGs and non-CPGs. Thus highlighting the importance of CPGs as compared to non-CPGs in drug discovery and disease pathogenesis.

  16. Recent advances in understanding carotenoid-derived signaling molecules in regulating plant growth and development.

    PubMed

    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.

  17. JMJD8 is a positive regulator of TNF-induced NF-κB signaling.

    PubMed

    Yeo, Kok Siong; Tan, Ming Cheang; Wong, Wan Ying; Loh, Sheng Wei; Lam, Yi Lyn; Tan, Chin Leng; Lim, Yat-Yuen; Ea, Chee-Kwee

    2016-09-27

    TNF-induced signaling mediates pleiotropic biological consequences including inflammation, immunity, cell proliferation and apoptosis. Misregulation of TNF signaling has been attributed as a major cause of chronic inflammatory diseases and cancer. Jumonji domain-containing protein 8 (JMJD8) belongs to the JmjC family. However, only part of the family members has been described as hydroxylase enzymes that function as histone demethylases. Here, we report that JMJD8 positively regulates TNF-induced NF-κB signaling. Silencing the expression of JMJD8 using RNA interference (RNAi) greatly suppresses TNF-induced expression of several NF-κB-dependent genes. Furthermore, knockdown of JMJD8 expression reduces RIP ubiquitination, IKK kinase activity, delays IκBα degradation and subsequently blocks nuclear translocation of p65. In addition, JMJD8 deficiency enhances TNF-induced apoptosis. Taken together, these findings indicate that JMJD8 functions as a positive regulator of TNF-induced NF-κB signaling.

  18. Regulated unfolding: a basic principle of intraprotein signaling in modular proteins.

    PubMed

    Schultz, Joachim E; Natarajan, Janani

    2013-11-01

    Modular proteins possess N-terminal sensor domains connected with different C-terminal output domains. Different output domains, for example, phosphodiesterases adenylyl cyclases, are regulated by identical N-terminal domains. Therefore, the mechanisms of intraprotein signaling share properties suitable to regulation of disparate output enzymes, which see the same signal but react differently. The common denominator is a reversible switch of folding/unfolding that connects sensor and output domains. In the inhibited state, output domains are restrained, whereas in the activated state domains are released to assemble according to intrinsic domain properties. We review recent work investigating the mechanism of intraprotein signaling and discuss how this signaling mechanism may have contributed to the evolutionary diversity of specific small molecule-binding domains without loss of regulatory properties.

  19. Phosphoinositide lipid phosphatases: natural regulators of phosphoinositide 3-kinase signaling in T lymphocytes.

    PubMed

    Harris, Stephanie J; Parry, Richard V; Westwick, John; Ward, Stephen G

    2008-02-01

    The phosphoinositide 3-kinase signaling pathway has been implicated in a range of T lymphocyte cellular functions, particularly growth, proliferation, cytokine secretion, and survival. Dysregulation of phosphoinositide 3-kinase-dependent signaling and function in leukocytes, including B and T lymphocytes, has been implicated in many inflammatory and autoimmune diseases. As befits a pivotal signaling cascade, several mechanisms exist to ensure that the pathway is tightly regulated. This minireview focuses on two lipid phosphatases, viz. the 3'-phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome 10) and SHIP (Src homology 2 domain-containing inositol-5-phosphatase). We discuss their role in regulating T lymphocyte signaling as well their potential as future therapeutic targets.

  20. The human adaptor SARM negatively regulates adaptor protein TRIF-dependent Toll-like receptor signaling.

    PubMed

    Carty, Michael; Goodbody, Rory; Schröder, Martina; Stack, Julianne; Moynagh, Paul N; Bowie, Andrew G

    2006-10-01

    Toll-like receptors discriminate between different pathogen-associated molecules and activate signaling cascades that lead to immune responses. The specificity of Toll-like receptor signaling occurs by means of adaptor proteins containing Toll-interleukin 1 receptor (TIR) domains. Activating functions have been assigned to four TIR adaptors: MyD88, Mal, TRIF and TRAM. Here we characterize a fifth TIR adaptor, SARM, as a negative regulator of TRIF-dependent Toll-like receptor signaling. Expression of SARM blocked gene induction 'downstream' of TRIF but not of MyD88. SARM associated with TRIF, and 'knockdown' of endogenous SARM expression by interfering RNA led to enhanced TRIF-dependent cytokine and chemokine induction. Thus, the fifth mammalian TIR adaptor SARM is a negative regulator of Toll-like receptor signaling.

  1. Canonical Wnt signalling regulates epithelial patterning by modulating levels of laminins in zebrafish appendages.

    PubMed

    Nagendran, Monica; Arora, Prateek; Gori, Payal; Mulay, Aditya; Ray, Shinjini; Jacob, Tressa; Sonawane, Mahendra

    2015-01-15

    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.

  2. 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

  3. Regulation of Smoothened Trafficking and Hedgehog Signaling by the SUMO Pathway.

    PubMed

    Ma, Guoqiang; Li, Shuang; Han, Yuhong; Li, Shuangxi; Yue, Tao; Wang, Bing; Jiang, Jin

    2016-11-21

    Hedgehog (Hh) signaling plays a central role in development and diseases. Hh activates its signal transducer and GPCR-family protein Smoothened (Smo) by inducing Smo phosphorylation, but whether Smo is activated through other post-translational modifications remains unexplored. Here we show that sumoylation acts in parallel with phosphorylation to promote Smo cell-surface expression and Hh signaling. We find that Hh stimulates Smo sumoylation by dissociating it from a desumoylation enzyme Ulp1. Sumoylation of Smo in turn recruits a deubiquitinase UBPY/USP8 to antagonize Smo ubiquitination and degradation, leading to its cell-surface accumulation and elevated Hh pathway activity. We also provide evidence that Shh stimulates sumoylation of mammalian Smo (mSmo) and that sumoylation promotes ciliary localization of mSmo and Shh pathway activity. Our findings reveal a conserved mechanism whereby the SUMO pathway promotes Hh signaling by regulating Smo subcellular localization and shed light on how sumoylation regulates membrane protein trafficking.

  4. Negative regulation of IL-17-mediated signaling and inflammation by ubiquitin-specific protease 25

    PubMed Central

    Zhong, Bo; Liu, Xikui; Wang, Xiaohu; Chang, Seon Hee; Liu, Xindong; Wang, Aibo; Reynolds, Joseph M.; Dong, Chen

    2012-01-01

    Interleukin 17 (IL-17) plays an important role in infection and autoimmunity; how it signals remains poorly understood. In this study, we identified ubiquitin-specific protease 25 (USP25) as a negative regulator of IL-17-mediated signaling and inflammation. Overexpression of USP25 inhibited IL-17-triggered signaling, while USP25 deficiency resulted in increased phosphorylation of IκBα and Jnk, increased expression of chemokines and cytokines as well as prolonged half-life of Cxcl1 mRNA following IL-17 treatment. Consistently, Usp25-/- mice exhibited increased sensitivity to IL-17-dependent inflammation and autoimmunity in vivo. Mechanistically, IL-17 stimulation induced the association of USP25 with TRAF5 and TRAF6 and USP25 induced removal of Act1-mediated K63-linked ubiquitination in TRAF5 and TRAF6. Thus, our results demonstrate that USP25 is a deubiquitinating enzyme (DUB) that negatively regulates IL-17-triggered signaling. PMID:23042150

  5. System-level mapping of Escherichia coli response regulator dimerization with FRET hybrids

    PubMed Central

    Gao, Rong; Tao, Yuan; Stock, Ann M

    2008-01-01

    Two-component signal transduction, featuring highly conserved histidine kinases (HKs) and response regulators (RRs), is one of the most prevalent signalling schemes in prokaryotes. RRs function as phosphorylation-activated switches to mediate diverse output responses, mostly via transcription regulation. As bacterial genomes typically encode multiple two-component proteins for distinct signalling pathways, the sequence and structural similarities of RR receiver domains create significant challenges to maintain interaction specificity. It is especially demanding for members of the OmpR/PhoB subfamily, the largest RR subfamily, which share a conserved dimerization interface for phosphorylation-mediated transcription regulation. We developed a strategy to investigate RR interaction by analysing Förster resonance energy transfer (FRET) between cyan fluorescent protein (CFP)- and yellow fluorescent protein (YFP)-fused RRs in vitro. Using the Escherichia coli RR PhoB as a model system, we were able to observe phosphorylation-dependent FRET between fluorescent protein (FP)–PhoB proteins and validated the FRET method by determining dimerization affinity and dimerization-coupled phosphorylation kinetics that recapitulated values determined by alternative methods. Further application of the FRET method to all E. coli OmpR/PhoB subfamily RRs revealed that phosphorylation–activated RR interaction is indeed a common theme for OmpR/PhoB subfamily RRs and these RRs display significant interaction specificity. Weak hetero-pair interactions were also identified between several different RRs, suggesting potential cross-regulation between distinct pathways. PMID:18631241

  6. 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

  7. Conversion of danger signals into cytokine signals by hematopoietic stem and progenitor cells for regulation of stress-induced hematopoiesis.

    PubMed

    Zhao, Jimmy L; Ma, Chao; O'Connell, Ryan M; Mehta, Arnav; DiLoreto, Race; Heath, James R; Baltimore, David

    2014-04-03

    During an infection, the body increases the output of mature immune cells in order to fight off the pathogen. Despite convincing evidence that hematopoietic stem and progenitor cells (HSPCs) can sense pathogens directly, how this contributes to hematopoietic cell output remains unknown. Here, we have combined mouse models with a single-cell proteomics platform to show that, in response to Toll-like receptor stimulation, short-term HSCs and multipotent progenitor cells produce copious amounts of diverse cytokines through nuclear factor κB (NF-κB) signaling. Interestingly, the cytokine production ability of HSPCs trumps mature immune cells in both magnitude and breadth. Among cytokines produced by HSPCs, IL-6 is a particularly important regulator of myeloid differentiation and HSPC proliferation in a paracrine manner and in mediating rapid myeloid cell recovery during neutropenia. This study has uncovered an important property of HSPCs that enables them to convert danger signals into versatile cytokine signals for the regulation of stress hematopoiesis.

  8. Pancreas lineage allocation and specification are regulated by sphingosine-1-phosphate signalling

    PubMed Central

    Serafimidis, Ioannis; Rodriguez-Aznar, Eva; Lesche, Mathias; Yoshioka, Kazuaki; Takuwa, Yoh; Dahl, Andreas; Pan, Duojia; Gavalas, Anthony

    2017-01-01

    During development, progenitor expansion, lineage allocation, and implementation of differentiation programs need to be tightly coordinated so that different cell types are generated in the correct numbers for appropriate tissue size and function. Pancreatic dysfunction results in some of the most debilitating and fatal diseases, including pancreatic cancer and diabetes. Several transcription factors regulating pancreas lineage specification have been identified, and Notch signalling has been implicated in lineage allocation, but it remains unclear how these processes are coordinated. Using a combination of genetic approaches, organotypic cultures of embryonic pancreata, and genomics, we found that sphingosine-1-phosphate (S1p), signalling through the G protein coupled receptor (GPCR) S1pr2, plays a key role in pancreas development linking lineage allocation and specification. S1pr2 signalling promotes progenitor survival as well as acinar and endocrine specification. S1pr2-mediated stabilisation of the yes-associated protein (YAP) is essential for endocrine specification, thus linking a regulator of progenitor growth with specification. YAP stabilisation and endocrine cell specification rely on Gαi subunits, revealing an unexpected specificity of selected GPCR intracellular signalling components. Finally, we found that S1pr2 signalling posttranscriptionally attenuates Notch signalling levels, thus regulating lineage allocation. Both S1pr2-mediated YAP stabilisation and Notch attenuation are necessary for the specification of the endocrine lineage. These findings identify S1p signalling as a novel key pathway coordinating cell survival, lineage allocation, and specification and linking these processes by regulating YAP levels and Notch signalling. Understanding lineage allocation and specification in the pancreas will shed light in the origins of pancreatic diseases and may suggest novel therapeutic approaches. PMID:28248965

  9. Activin receptor signaling regulates cocaine-primed behavioral and morphological plasticity.

    PubMed

    Gancarz, Amy M; Wang, Zi-Jun; Schroeder, Gabrielle L; Damez-Werno, Diane; Braunscheidel, Kevin M; Mueller, Lauren E; Humby, Monica S; Caccamise, Aaron; Martin, Jennifer A; Dietz, Karen C; Neve, Rachael L; Dietz, David M

    2015-07-01

    Activin receptor signaling, including the transcription factor Smad3, was upregulated in the rat nucleus accumbens (NAc) shell following withdrawal from cocaine. Direct genetic and pharmacological manipulations of this pathway bidirectionally altered cocaine seeking while governing morphological plasticity in NAc neurons. Thus, Activin/Smad3 signaling is induced following withdrawal from cocaine, and such regulation may be a key molecular mechanism underlying behavioral and cellular plasticity in the brain following cocaine self-administration.

  10. OTUB1 modulates c-IAP1 stability to regulate signalling pathways

    PubMed Central

    Goncharov, Tatiana; Niessen, Kyle; de Almagro, Maria Cristina; Izrael-Tomasevic, Anita; Fedorova, Anna V; Varfolomeev, Eugene; Arnott, David; Deshayes, Kurt; Kirkpatrick, Donald S; Vucic, Domagoj

    2013-01-01

    The cellular inhibitor of apoptosis (c-IAP) proteins are E3 ubiquitin ligases that are critical regulators of tumour necrosis factor (TNF) receptor (TNFR)-mediated signalling. Through their E3 ligase activity c-IAP proteins promote ubiquitination of receptor-interaction protein 1 (RIP1), NF-κB-inducing kinase (NIK) and themselves, and regulate the assembly of TNFR signalling complexes. Consequently, in the absence of c-IAP proteins, TNFR-mediated activation of NF-κB and MAPK pathways and the induction of gene expression are severely reduced. Here, we describe the identification of OTUB1 as a c-IAP-associated deubiquitinating enzyme that regulates c-IAP1 stability. OTUB1 disassembles K48-linked polyubiquitin chains from c-IAP1 in vitro and in vivo within the TWEAK receptor-signalling complex. Downregulation of OTUB1 promotes TWEAK- and IAP antagonist-stimulated caspase activation and cell death, and enhances c-IAP1 degradation. Furthermore, knockdown of OTUB1 reduces TWEAK-induced activation of canonical NF-κB and MAPK signalling pathways and modulates TWEAK-induced gene expression. Finally, suppression of OTUB1 expression in zebrafish destabilizes c-IAP (Birc2) protein levels and disrupts fish vasculature. These results suggest that OTUB1 regulates NF-κB and MAPK signalling pathways and TNF-dependent cell death by modulating c-IAP1 stability. PMID:23524849

  11. Caveolae regulate Smad signaling as verified by novel imaging and system biology approaches.

    PubMed

    Saldanha, Sven; Bragdon, Beth; Moseychuk, Oleksandra; Bonor, Jeremy; Dhurjati, Prasad; Nohe, Anja

    2013-05-01

    The contribution of caveolae in Bone Morphogenetic Protein 2 (BMP2) activated Smad signaling was quantified using a system biology approach. BMP2 plays crucial roles during processes such as hematopoiesis, embryogenesis, and skeletal development. BMP2 signaling is tightly regulated on the plasma membrane by its receptors. The localization of BMP receptors in caveolae and endocytosis through clathrin-coated pits are thought to regulate the signaling; however the conclusions in the current literature are inconsistent. Therefore published literature was used to establish a mathematical model that was validated using confocal AFM (atomic force microscopy), confocal microscopy, and sucrose density centrifugation followed by Western blots, and reporter gene assays. The model and experiments confirmed that both caveolae and CCPs regulate the Smad-dependent signaling pathway, however caveolae are centers at the plasma membrane where receptor-ligand interaction is crucial, Smad phosphorylation occurs, and a high degree of Smad signaling is regulated. This demonstrates a role for caveolae that needs to be considered and further studied.

  12. Regulation of striatal dopamine responsiveness by Notch/RBP-J signaling.

    PubMed

    Toritsuka, M; Kimoto, S; Muraki, K; Kitagawa, M; Kishimoto, T; Sawa, A; Tanigaki, K

    2017-03-07

    Dopamine signaling is essential for reward learning and fear-related learning, and thought to be involved in neuropsychiatric diseases. However, the molecular mechanisms underlying the regulation of dopamine responsiveness is unclear. Here we show the critical roles of Notch/RBP-J signaling in the regulation of dopamine responsiveness in the striatum. Notch/RBP-J signaling regulates various neural cell fate specification, and neuronal functions in the adult central nervous system. Conditional deletion of RBP-J specifically in neuronal cells causes enhanced response to apomorphine, a non-selective dopamine agonist, and SKF38393, a D1 agonist, and impaired dopamine-dependent instrumental avoidance learning, which is corrected by SCH23390, a D1 antagonist. RBP-J deficiency drastically reduced dopamine release in the striatum and caused a subtle decrease in the number of dopaminergic neurons. Lentivirus-mediated gene transfer experiments showed that RBP-J deficiency in the striatum was sufficient for these deficits. These findings demonstrated that Notch/RBP-J signaling regulates dopamine responsiveness in the striatum, which may explain the mechanism whereby Notch/RBP-J signaling affects an individual's susceptibility to neuropsychiatric disease.

  13. Interferon-gamma expression by Th1 effector T cells mediated by the p38 MAP kinase signaling pathway.

    PubMed Central

    Rincón, M; Enslen, H; Raingeaud, J; Recht, M; Zapton, T; Su, M S; Penix, L A; Davis, R J; Flavell, R A

    1998-01-01

    Signal transduction via MAP kinase pathways plays a key role in a variety of cellular responses, including growth factor-induced proliferation, differentiation and cell death. In mammalian cells, p38 MAP kinase can be activated by multiple stimuli, such as pro-inflammatory cytokines and environmental stress. Although p38 MAP kinase is implicated in the control of inflammatory responses, the molecular mechanisms remain unclear. Upon activation, CD4+ T cells differentiate into Th2 cells, which potentiate the humoral immune response or pro-inflammatory Th1 cells. Here, we show that pyridinyl imidazole compounds (specific inhibitors of p38 MAP kinase) block the production of interferon-gamma (IFNgamma) by Th1 cells without affecting IL-4 production by Th2 cells. These drugs also inhibit transcription driven by the IFNgamma promoter. In transgenic mice, inhibition of the p38 MAP kinase pathway by the expression of dominant-negative p38 MAP kinase results in selective impairment of Th1 responses. In contrast, activation of the p38 MAP kinase pathway by the expression of constitutivelyactivated MAP kinase kinase 6 in transgenic mice caused increased production of IFNgamma during the differentiation and activation of Th1 cells. Together, these data demonstrate that the p38 MAP kinase is relevant for Th1 cells, not Th2 cells, and that inhibition of p38 MAP kinase represents a possible site of therapeutic intervention in diseases where a predominant Th1 immune response leads to a pathological outcome. Moreover, our study provides an additional mechanism by which the p38 MAP kinase pathway controls inflammatory responses. PMID:9582275

  14. Integrin-mediated Ras–Extracellular Regulated Kinase (ERK) Signaling Regulates Interferon γ Production in Human Natural Killer Cells

    PubMed Central

    Mainiero, Fabrizio; Gismondi, Angela; Soriani, Alessandra; Cippitelli, Marco; Palmieri, Gabriella; Jacobelli, Jordan; Piccoli, Mario; Frati, Luigi; Santoni, Angela

    1998-01-01

    Recent evidence indicates that integrin engagement results in the activation of biochemical signaling events important for regulating different cell functions, such as migration, adhesion, proliferation, differentiation, apoptosis, and specific gene expression. Here, we report that β1 integrin ligation on human natural killer (NK) cells results in the activation of Ras/mitogen-activated protein kinase pathways. Formation of Shc–growth factor receptor–bound protein 2 (Grb2) and Shc–proline-rich tyrosine kinase 2–Grb2 complexes are the receptor-proximal events accompanying the β1 integrin–mediated Ras activation. In addition, we demonstrate that ligation of β1 integrins results in the stimulation of interferon γ (IFN-γ) production, which is under the control of extracellular signal–regulated kinase 2 activation. Overall, our data indicate that β1 integrins, by delivering signals capable of triggering IFN-γ production, may function as NK-activating receptors. PMID:9763606

  15. The response to inositol: regulation of glycerolipid metabolism and stress response signaling in yeast

    PubMed Central

    Henry, Susan A.; Gaspar, Maria L.; Jesch, Stephen A.

    2014-01-01

    This article focuses on discoveries of the mechanisms governing the regulation of glycerolipid metabolism and stress response signaling in response to the phospholipid precursor, inositol. The regulation of glycerolipid lipid metabolism in yeast in response to inositol is highly complex, but increasingly well understood, and the roles of individual lipids in stress response are also increasingly well characterized. Discoveries that have emerged over several decades of genetic, molecular and biochemical analyses of metabolic, regulatory and signaling responses of yeast cells, both mutant and wild type, to the availability of the phospholipid precursor, inositol are discussed. PMID:24418527

  16. Mitochondrial respiration links TOR Complex 2 signaling to calcium regulation and autophagy.

    PubMed

    Vlahakis, Ariadne; Lopez Muniozguren, Nerea; Powers, Ted

    2017-03-21

    The Target of Rapamycin (TOR) kinase is a conserved regulator of cell growth and functions within 2 different protein complexes, TORC1 and TORC2, where TORC2 positively controls macroautophagy/autophagy during amino acid starvation. Under these conditions, TORC2 signaling inhibits the activity of the calcium-regulated phosphatase calcineurin and promotes the general amino acid control (GAAC) response and autophagy. Here we demonstrate that TORC2 regulates calcineurin by controlling the respiratory activity of mitochondria. In particular, we find that mitochondrial oxidative stress affects the calcium channel regulatory protein Mid1, which we show is an essential upstream activator of calcineurin. Thus, these findings describe a novel regulation for autophagy that involves TORC2 signaling, mitochondrial respiration, and calcium homeostasis.

  17. GABA signalling modulates plant growth by directly regulating the activity of plant-specific anion transporters.

    PubMed

    Ramesh, Sunita A; Tyerman, Stephen D; Xu, Bo; Bose, Jayakumar; Kaur, Satwinder; Conn, Vanessa; Domingos, Patricia; Ullah, Sana; Wege, Stefanie; Shabala, Sergey; Feijó, José A; Ryan, Peter R; Gilliham, Matthew; Gillham, Matthew

    2015-07-29

    The non-protein amino acid, gamma-aminobutyric acid (GABA) rapidly accumulates in plant tissues in response to biotic and abiotic stress, and regulates plant growth. Until now it was not known whether GABA exerts its effects in plants through the regulation of carbon metabolism or via an unidentified signalling pathway. Here, we demonstrate that anion flux through plant aluminium-activated malate transporter (ALMT) proteins is activated by anions and negatively regulated by GABA. Site-directed mutagenesis of selected amino acids within ALMT proteins abolishes GABA efficacy but does not alter other transport properties. GABA modulation of ALMT activity results in altered root growth and altered root tolerance to alkaline pH, acid pH and aluminium ions. We propose that GABA exerts its multiple physiological effects in plants via ALMT, including the regulation of pollen tube and root growth, and that GABA can finally be considered a legitimate signalling molecule in both the plant and animal kingdoms.

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

    PubMed

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

    2015-12-10

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

  19. Target of Rapamycin (TOR) Regulates Growth in Response to Nutritional Signals.

    PubMed

    Weisman, Ronit

    2016-10-01

    All organisms can respond to the availability of nutrients by regulating their metabolism, growth, and cell division. Central to the regulation of growth in response to nutrient availability is the target of rapamycin (TOR) signaling that is composed of two structurally distinct complexes: TOR complex 1 (TORC1) and TOR complex 2 (TORC2). The TOR genes were first identified in yeast as target of rapamycin, a natural product of a soil bacterium, which proved beneficial as an immunosuppressive and anticancer drug and is currently being tested for a handful of other pathological conditions including diabetes, neurodegeneration, and age-related diseases. Studies of the TOR pathway unraveled a complex growth-regulating network. TOR regulates nutrient uptake, transcription, protein synthesis and degradation, as well as metabolic pathways, in a coordinated manner that ensures that cells grow or cease growth in response to nutrient availability. The identification of specific signals and mechanisms that stimulate TOR signaling is an active and exciting field of research that has already identified nitrogen and amino acids as key regulators of TORC1 activity. The signals, as well as the cellular functions of TORC2, are far less well understood. Additional open questions in the field concern the relationships between TORC1 and TORC2, as well as the links with other nutrient-responsive pathways. Here I review the main features of TORC1 and TORC2, with a particular focus on yeasts as model organisms.

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

    PubMed Central

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

    2015-01-01

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

  1. ERK signaling pathway regulates sleep duration through activity-induced gene expression during wakefulness.

    PubMed

    Mikhail, Cyril; Vaucher, Angélique; Jimenez, Sonia; Tafti, Mehdi

    2017-01-24

    Wakefulness is accompanied by experience-dependent synaptic plasticity and an increase in activity-regulated gene transcription. Wake-induced genes are certainly markers of neuronal activity and may also directly regulate the duration of and need for sleep. We stimulated murine cortical cultures with the neuromodulatory signals that are known to control wakefulness in the brain and found that norepinephrine alone or a mixture of these neuromodulators induced activity-regulated gene transcription. Pharmacological inhibition of the various signaling pathways involved in the regulation of gene expression indicated that the extracellular signal-regulated kinase (ERK) pathway is the principal one mediating the effects of waking neuromodulators on gene expression. In mice, ERK phosphorylation in the cortex increased and decreased with wakefulness and sleep. Whole-body or cortical neuron-specific deletion of Erk1 or Erk2 significantly increased the duration of wakefulness in mice, and pharmacological inhibition of ERK phosphorylation decreased sleep duration and increased the duration of wakefulness bouts. Thus, this signaling pathway, which is highly conserved from Drosophila to mammals, is a key pathway that links waking experience-induced neuronal gene expression to sleep duration and quality.

  2. ASIC1 promotes differentiation of neuroblastoma by negatively regulating Notch signaling pathway.

    PubMed

    Liu, Mingli; Inoue, Koichi; Leng, Tiandong; Zhou, An; Guo, Shanchun; Xiong, Zhi-Gang

    2017-01-31

    In neurons, up-regulation of Notch activity either inhibits neurite extension or causes retraction of neurites. Conversely, inhibition of Notch1 facilitates neurite extension. Acid-sensing ion channels (ASICs) are a family of proton-gated cation channels, which play critical roles in synaptic plasticity, learning and memory and spine morphogenesis. Our pilot proteomics data from ASIC1a knock out mice implicated that ASIC1a may play a role in regulating Notch signaling, therefore, we explored whether or not ASIC1a regulates neurite growth during neuronal development through Notch signaling. In this study, we determined the effects of ASIC1a on neurite growth in a mouse neuroblastoma cell line, NS20Y cells, by modulating ASIC1a expression. We also determined the relationship between ASIC1a and Notch signaling on neuronal differentiation. Our results showed that down-regulation of ASIC1a in NS20Y cells inhibits CPT-cAMP induced neurite growth, while over expression of ASIC1a promotes its growth. In addition, down-regulation of ASIC1a increased the expression of Notch1 and its target gene Survivin while inhibitor of Notch significantly prevented the neurite extension induced by ASIC1a in NS20Y cells. These data indicate that Notch1 signaling may be required for ASIC1a-mediated neurite growth and neuronal differentiation.

  3. PP6 controls T cell development and homeostasis by negatively regulating distal TCR signaling.

    PubMed

    Ye, Jian; Shi, Hao; Shen, Ye; Peng, Chao; Liu, Yan; Li, Chenyu; Deng, Kejing; Geng, Jianguo; Xu, Tian; Zhuang, Yuan; Zheng, Biao; Tao, Wufan

    2015-02-15

    T cell development and homeostasis are both regulated by TCR signals. Protein phosphorylation and dephosphorylation, which are catalyzed by protein kinases and phosphatases, respectively, serve as important switches controlling multiple downstream pathways triggered by TCR recognition of Ags. It has been well documented that protein tyrosine phosphatases are involved in negative regulation of proximal TCR signaling. However, how TCR signals are terminated or attenuated in the distal TCR signaling pathways is largely unknown. We investigated the function of Ser/Thr protein phosphatase (PP) 6 in TCR signaling. T cell lineage-specific ablation of PP6 in mice resulted in enhanced thymic positive and negative selection, and preferential expansion of fetal-derived, IL-17-producing Vγ6Vδ1(+) T cells. Both PP6-deficient peripheral CD4(+) helper and CD8(+) cytolytic cells could not maintain a naive state and became fast-proliferating and short-lived effector cells. PP6 deficiency led to profound hyperactivation of multiple distal TCR signaling molecules, including MAPKs, AKT, and NF-κB. Our studies demonstrate that PP6 acts as a critical negative regulator, not only controlling both αβ and γδ lineage development, but also maintaining naive T cell homeostasis by preventing their premature activation before Ag stimulation.

  4. Planarian Hedgehog/Patched establishes anterior–posterior polarity by regulating Wnt signaling

    PubMed Central

    Yazawa, Shigenobu; Umesono, Yoshihiko; Hayashi, Tetsutaro; Tarui, Hiroshi; Agata, Kiyokazu

    2009-01-01

    Despite long-standing interest, the molecular mechanisms underlying the establishment of anterior–posterior (AP) polarity remain among the unsolved mysteries in metazoans. In the planarians (a family of flatworms), canonical Wnt/β-catenin signaling is required for posterior specification, as it is in many animals. However, the molecular mechanisms regulating the posterior-specific induction of Wnt genes according to the AP polarity have remained unclear. Here, we demonstrate that Hedgehog (Hh) signaling is responsible for the establishment of AP polarity via its regulation of the transcription of Wnt family genes during planarian regeneration. We found that RNAi gene knockdown of Dugesia japonica patched (Djptc) caused ectopic tail formation in the anterior blastema of body fragments, resulting in bipolar-tails regeneration. In contrast, RNAi of hedgehog (Djhh) and gli (Djgli) caused bipolar-heads regeneration. We show that Patched-mediated Hh signaling was crucial for posterior specification, which is established by regulating the transcription of Wnt genes via downstream Gli activity. Moreover, differentiated cells were responsible for the posterior specification of undifferentiated stem cells through Wnt/β-catenin signaling. Surprisingly, Djhh was expressed in neural cells all along the ventral nerve cords (along the AP axis), but not in the posterior blastema of body fragments, where the expression of Wnt genes was induced for posteriorization. We therefore propose that Hh signals direct head or tail regeneration according to the AP polarity, which is established by Hh signaling activity along the body's preexisting nervous system. PMID:20018728

  5. Kisspeptin cell-specific PI3K signaling regulates hypothalamic kisspeptin expression and participates in the regulation of female fertility

    PubMed Central

    Beymer, Matthew; Negrón, Ariel L.; Yu, Guiqin; Wu, Samuel; Mayer, Christian; Lin, Richard Z.; Boehm, Ulrich

    2014-01-01

    Hypothalamic kisspeptin neurons integrate and translate cues from the internal and external environments that regulate gonadotropin-releasing hormone (GnRH) secretion and maintain fertility in mammals. However, the intracellular signaling pathways utilized to translate such information into changes in kisspeptin expression, release, and ultimately activation of the kisspeptin-receptive GnRH network have not yet been identified. PI3K is an important signaling node common to many peripheral factors known to regulate kisspeptin expression and GnRH release. We investigated whether PI3K signaling regulates hypothalamic kisspeptin expression, pubertal development, and adult fertility in mice. We generated mice with a kisspeptin cell-specific deletion of the PI3K catalytic subunits p110α and p110β (kiss-p110α/β-KO). Using in situ hybridization, we examined Kiss1 mRNA expression in gonad-intact, gonadectomized (Gdx), and Gdx + steroid-replaced mice. Kiss1 cell number in the anteroventral periventricular hypothalamus (AVPV) was significantly reduced in intact females but not in males. In contrast, compared with WT and regardless of steroid hormone status, Kiss1 cell number was lower in the arcuate (ARC) of kiss-p110α/β-KO males, but it was unaffected in females. Both intact Kiss-p110α/β-KO males and females had reduced ARC kisspeptin-immunoreactive (IR) fibers compared with WT animals. Adult kiss-p110α/β-KO males had significantly lower circulating luteinizing hormone (LH) levels, whereas pubertal development and fertility were unaffected in males. Kiss-p110α/β-KO females exhibited a reduction in fertility despite normal pubertal development, LH levels, and estrous cyclicity. Our data show that PI3K signaling is important for the regulation of hypothalamic kisspeptin expression and contributes to normal fertility in females. PMID:25269483

  6. The FRK/RAK-SHB signaling cascade: a versatile signal-transduction pathway that regulates cell survival, differentiation and proliferation.

    PubMed

    Annerén, Cecilia; Lindholm, Cecilia K; Kriz, Vitezslav; Welsh, Michael

    2003-06-01

    Recent experiments have unravelled novel signal transduction pathways that involve the SRC homology 2 (SH2) domain adapter protein SHB. SHB is ubiquitously expressed and contains proline rich motifs, a phosphotyrosine binding (PTB) domain, tyrosine phosphorylation sites and an SH2 domain and serves a role in generating signaling complexes in response to tyrosine kinase activation. SHB mediates certain responses in platelet-derived growth factor (PDGF) receptor-, fibroblast growth factor (FGF) receptor-, neural growth factor (NGF) receptor TRKA-, T cell receptor-, interleukin-2 (IL-2) receptor- and focal adhesion kinase- (FAK) signaling. Upstream of SHB in some cells lies the SRC-like FYN-Related Kinase FRK/RAK (also named BSK/IYK or GTK). FRK/RAK and SHB exert similar effects when overexpressed in rat phaeochromocytoma (PC12) and beta-cells, where they both induce PC12 cell differentiation and beta-cell proliferation. Furthermore, beta-cell apoptosis is augmented by these proteins under conditions that cause beta-cell degeneration. The FRK/RAK-SHB responses involve FAK and insulin receptor substrates (IRS) -1 and -2. Besides regulating apoptosis, proliferation and differentiation, SHB is also a component of the T cell receptor (TCR) signaling response. In Jurkat T cells, SHB links several signaling components with the TCR and is thus required for IL-2 production. In endothelial cells, SHB both promotes apoptosis under conditions that are anti-angiogenic, but is also required for proper mitogenicity, spreading and tubular morphogenesis. In embryonic stem cells, dominant-negative SHB (R522K) prevents early cavitation of embryoid bodies and reduces differentiation to cells expressing albumin, amylase, insulin and glucagon, suggesting a role of SHB in development. In summary, SHB is a versatile signal transduction molecule that produces diverse biological responses in different cell types under various conditions. SHB operates downstream of GTK in cells that express

  7. Dietary Regulation of PTEN Signaling and Mammary Tumor Initiating Cells: Implications for Breast Cancer Prevention

    DTIC Science & Technology

    2012-07-01

    Results suggest that dietary SPI negatively regulates local (MaSC- enriched population) and systemic IL6 production . Based on the signaling pathways...Identified local (MaSC-enriched population) and systemic IL6 production as a central mediator of dietary effects on regulation of mammary stem...Epidemiological and case– control studies have shown a 2- to 8-fold lower occurrence of the disease in Asian women whose early intake of soy products is 10–20

  8. Regulation of Hippo signaling by Jun kinase signaling during compensatory cell proliferation and regeneration, and in neoplastic tumors.

    PubMed

    Sun, Gongping; Irvine, Kenneth D

    2011-02-01

    When cells undergo apoptosis, they can stimulate the proliferation of nearby cells, a process referred to as compensatory cell proliferation. The stimulation of proliferation in response to tissue damage or removal is also central to epimorphic regeneration. The Hippo signaling pathway has emerged as an important regulator of growth during normal development and oncogenesis from Drosophila to humans. Here we show that induction of apoptosis in the Drosophila wing imaginal disc stimulates activation of the Hippo pathway transcription factor Yorkie in surviving and nearby cells, and that Yorkie is required for the ability of the wing to regenerate after genetic ablation of the wing primordia. Induction of apoptosis activates Yorkie through the Jun kinase pathway, and direct activation of Jun kinase signaling also promotes Yorkie activation in the wing disc. We also show that depletion of neoplastic tumor suppressor genes, including lethal giant larvae and discs large, or activation of aPKC, activates Yorkie through Jun kinase signaling, and that Jun kinase activation is necessary, but not sufficient, for the disruption of apical-basal polarity associated with loss of lethal giant larvae. Our observations identify Jnk signaling as a modulator of Hippo pathway activity in wing imaginal discs, and implicate Yorkie activation in compensatory cell proliferation and disc regeneration.

  9. Drug-induced alterations in the extracellular signal-regulated kinase (ERK) signalling pathway: implications for reinforcement and reinstatement.

    PubMed

    Zhai, Haifeng; Li, Yanqin; Wang, Xi; Lu, Lin

    2008-02-01

    Drug addiction, characterized by high rates of relapse, is recognized as a kind of neuroadaptive disorder. Since the extracellular signal-regulated kinase (ERK) pathway is critical to neuroplasticity in the adult brain, understanding the role this pathway plays is important for understanding the molecular mechanism underlying drug addiction and relapse. Here, we review previous literatures that focus on the effects of exposure to cocaine, amphetamine, Delta(9)-tetrahydrocannabinol (THC), nicotine, morphine, and alcohol on ERK signaling in the mesocorticolimbic dopamine system; these alterations of ERK signaling have been thought to contribute to the drug's rewarding effects and to the long-term maladaptation induced by drug abuse. We then discuss the possible upstreams of the ERK signaling pathway activated by exposure of drugs of abuse and the environmental cues previously paired with drugs. Finally, we argue that since ERK activation is a key molecular process in reinstatement of conditioned place preference and drug self-administration, the pharmacological manipulation of the ERK pathway is a potential treatment strategy for drug addiction.

  10. TOR complex 2-Ypk1 signaling regulates actin polarization via reactive oxygen species.

    PubMed

    Niles, Brad J; Powers, Ted

    2014-12-01

    The evolutionarily conserved mTOR complex 2 (mTORC2) signaling pathway is an important regulator of actin cytoskeletal architecture and, as such, is a candidate target for preventing cancer cell motility and invasion. Remarkably, the precise mechanism(s) by which mTORC2 regulates the actin cytoskeleton have remained elusive. Here we show that in budding yeast, TORC2 and its downstream kinase Ypk1 regulate actin polarization by controlling reactive oxygen species (ROS) accumulation. Specifically, we find that TORC2-Ypk1 regulates actin polarization both by vacuole-related ROS, controlled by the phospholipid flippase kinase Fpk1 and sphingolipids, and by mitochondria-mediated ROS, controlled by the PKA subunit Tpk3. In addition, we find that the protein kinase C (Pkc1)/MAPK cascade, a well-established regulator of actin, acts downstream of Ypk1 to regulate ROS, in part by promoting degradation of the oxidative stress responsive repressor, cyclin C. Furthermore, we show that Ypk1 regulates Pkc1 activity through proper localization of Rom2 at the plasma membrane, which is also dependent on Fpk1 and sphingolipids. Together these findings demonstrate important links between TORC2/Ypk1 signaling, Fpk1, sphingolipids, Pkc1, and ROS as regulators of actin and suggest that ROS may play an important role in mTORC2-dependent dysregulation of the actin cytoskeleton in cancer cells.

  11. Desmosomes: Regulators of Cellular Signaling and Adhesion in Epidermal Health and Disease

    PubMed Central

    Johnson, Jodi L.; Najor, Nicole A.; Green, Kathleen J.

    2014-01-01

    Desmosomes are intercellular junctions that mediate cell–cell adhesion and anchor the intermediate filament network to the plasma membrane, providing mechanical resilience to tissues such as the epidermis and heart. In addition to their critical roles in adhesion, desmosomal proteins are emerging as mediators of cell signaling important for proper cell and tissue functions. In this review we highlight what is known about desmosomal proteins regulating adhesion and signaling in healthy skin—in morphogenesis, differentiation and homeostasis, wound healing, and protection against environmental damage. We also discuss how human diseases that target desmosome molecules directly or interfere indirectly with these mechanical and signaling functions to contribute to pathogenesis. PMID:25368015

  12. Quercitrin attenuates osteoporosis in ovariectomized rats by regulating mitogen-activated protein kinase (MAPK) signaling pathways.

    PubMed

    Xing, Li-Zhi; Ni, Huai-Jun; Wang, Yu-Ling

    2017-03-13

    MAPK signaling pathways are crucial in regulating osteogenesis, a genetic disorder affecting the bones. Quercitrin, a type of flavonoid, is widely distributed in nature and involved in many pharmacological activities. But its osteoprotective functions and mechanism in osteoporosis are far from being understood clearly. In this paper, the MAPK upregulation was observed in the ovariectomy-induced bone loss. Quercitrin was found to downregulate MAPK signaling pathways and prevent the ovariectomy-induced deterioration of bone mineral density (BMD), trabecular microstructure, and bone mechanical characteristics. In this study, quercitrin was seen to prevent the progression of the postmenopausal osteoporosis among the rats, which may be mediated by the downregulated MAPK signaling pathways.

  13. Neurotransmitters act as paracrine signals to regulate insulin secretion from the human pancreatic islet.

    PubMed

    Rodriguez-Diaz, Rayner; Menegaz, Danusa; Caicedo, Alejandro

    2014-08-15

    In this symposium review we discuss the role of neurotransmitters as paracrine signals that regulate pancreatic islet function. A large number of neurotransmitters and their receptors has been identified in the islet, but relatively little is known about their involvement in islet biology. Interestingly, neurotransmitters initially thought to be present in autonomic axons innervating the islet are also present in endocrine cells of the human islet. These neurotransmitters can thus be released as paracrine signals to help control hormone release. Here we propose that the role of neurotransmitters may extend beyond controlling endocrine cell function to work as signals modulating vascular flow and immune responses within the islet.

  14. Desmosomes: regulators of cellular signaling and adhesion in epidermal health and disease.

    PubMed

    Johnson, Jodi L; Najor, Nicole A; Green, Kathleen J

    2014-11-03

    Desmosomes are intercellular junctions that mediate cell-cell adhesion and anchor the intermediate filament network to the plasma membrane, providing mechanical resilience to tissues such as the epidermis and heart. In addition to their critical roles in adhesion, desmosomal proteins are emerging as mediators of cell signaling important for proper cell and tissue functions. In this review we highlight what is known about desmosomal proteins regulating adhesion and signaling in healthy skin-in morphogenesis, differentiation and homeostasis, wound healing, and protection against environmental damage. We also discuss how human diseases that target desmosome molecules directly or interfere indirectly with these mechanical and signaling functions to contribute to pathogenesis.

  15. Opposing actions of TGF{beta} and MAP kinase signaling in undifferentiated hen granulosa cells

    SciTech Connect

    Woods, Dori C.; Haugen, Morgan J.; Johnson, A.L. . E-mail: johnson.128@nd.edu

    2005-10-21

    The present studies were conducted to establish interactions between transforming growth factor (TGF)-{beta} and the epidermal growth factor (EGF) family members, TGF{alpha} and betacellulin (BTC), relative to proliferation and differentiation of granulosa cells in hen ovarian follicles. Results presented demonstrate expression of TGF{beta} isoforms, plus TGF{alpha}, BTC, and ErbB receptors in prehierarchal follicles, thus establishing the potential for autocrine/paracrine signaling and cross-talk within granulosa cells at the onset of differentiation. Treatment with TGF{alpha} or BTC increases levels of TGF{beta}1 mRNA in undifferentiated granulosa cells, while the selective inhibitor of mitogen activated protein kinase signaling, U0126, reverses these effects. Moreover, TGF{beta}1 attenuates c-myc mRNA expression and granulosa cell proliferation, while TGF{alpha} blocks both these inhibitory effects. Collectively, these data provide evidence that EGF family ligands regulate both the expression and biological actions of TGF{beta}1 in hen granulosa cells, and indicate that the timely interaction of these opposing factors is an important modulator of both granulosa cell proliferation and differentiation.

  16. Karrikins: Regulators Involved in Phytohormone Signaling Networks during Seed Germination and Seedling Development

    PubMed Central

    Meng, Yongjie; Shuai, Haiwei; Luo, Xiaofeng; Chen, Feng; Zhou, Wenguan; Yang, Wenyu; Shu, Kai

    2017-01-01

    Seed germination and early seedling establishment are critical stages during a plant’s life cycle. These stages are precisely regulated by multiple internal factors, including phytohormones and environmental cues such as light. As a family of small molecules discovered in wildfire smoke, karrikins (KARs) play a key role in various biological processes, including seed dormancy release, germination regulation, and seedling establishment. KARs show a high similarity with strigolactone (SL) in both chemical structure and signaling transduction pathways. Current evidence shows that KARs may regulate seed germination by mediating the biosynthesis and/or signaling transduction of abscisic acid (ABA), gibberellin (GA) and auxin [indoleacetic acid (IAA)]. Interestingly, KARs regulate seed germination differently in different species. Furthermore, the promotion effect on seedling establishment implies that KARs have a great potential application in alleviating shade avoidance response, which attracts more and more attention in plant molecular biology. In these processes, KARs may have complicated interactions with phytohormones, especially with IAA. In this updated review, we summarize the current understanding of the relationship between KARs and SL in the chemical structure, signaling pathway and the regulation of plant growth and development. Further, the crosstalk between KARs and phytohormones in regulating seed germination and seedling development and that between KARs and IAA during shade responses are discussed. Finally, future challenges and research directions for the KAR research field are suggested. PMID:28174573

  17. A Gibberellin-Mediated DELLA-NAC Signaling Cascade Regulates Cellulose Synthesis in Rice[OPEN

    PubMed Central

    Huang, Debao; Wang, Shaogan; Zhang, Baocai; Shang-Guan, Keke; Shi, Yanyun; Zhang, Dongmei; Liu, Xiangling; Wu, Kun; Xu, Zuopeng; Fu, Xiangdong; Zhou, Yihua

    2015-01-01

    Cellulose, which can be converted into numerous industrial products, has important impacts on the global economy. It has long been known that cellulose synthesis in plants is tightly regulated by various phytohormones. However, the underlying mechanism of cellulose synthesis regulation remains elusive. Here, we show that in rice (Oryza sativa), gibberellin (GA) signals promote cellulose synthesis by relieving the interaction between SLENDER RICE1 (SLR1), a DELLA repressor of GA signaling, and NACs, the top-layer transcription factors for secondary wall formation. Mutations in GA-related genes and physiological treatments altered the transcription of CELLULOSE SYNTHASE genes (CESAs) and the cellulose level. Multiple experiments demonstrated that transcription factors NAC29/31 and MYB61 are CESA regulators in rice; NAC29/31 directly regulates MYB61, which in turn activates CESA expression. This hierarchical regulation pathway is blocked by SLR1-NAC29/31 interactions. Based on the results of anatomical analysis and GA content examination in developing rice internodes, this signaling cascade was found to be modulated by varied endogenous GA levels and to be required for internode development. Genetic and gene expression analyses were further performed in Arabidopsis thaliana GA-related mutants. Altogether, our findings reveal a conserved mechanism by which GA regulates secondary wall cellulose synthesis in land plants and provide a strategy for manipulating cellulose production and plant growth. PMID:26002868

  18. Hedgehog is a positive regulator of FGF signalling during embryonic tracheal cell migration.

    PubMed

    Butí, Elisenda; Mesquita, Duarte; Araújo, Sofia J

    2014-01-01

    Cell migration is a widespread and complex process that is crucial for morphogenesis and for the underlying invasion and metastasis of human cancers. During migration, cells are steered toward target sites by guidance molecules that induce cell direction and movement through complex intracellular mechanisms. The spatio-temporal regulation of the expression of these guidance molecules is of extreme importance for both normal morphogenesis and human disease. One way to achieve this precise regulation is by combinatorial inputs of different transcription factors. Here we used Drosophila melanogaster mutants with migration defects in the ganglionic branches of the tracheal system to further clarify guidance regulation during cell migration. By studying the cellular consequences of overactivated Hh signalling, using ptc mutants, we found that Hh positively regulates Bnl/FGF levels during embryonic stages. Our results show that Hh modulates cell migration non-autonomously in the tissues surrounding the action of its activity. We further demonstrate that the Hh signalling pathway regulates bnl expression via Stripe (Sr), a zinc-finger transcription factor with homology to the Early Growth Response (EGR) family of vertebrate transcription factors. We propose that Hh modulates embryonic cell migration by participating in the spatio-temporal regulation of bnl expression in a permissive mode. By doing so, we provide a molecular link between the activation of Hh signalling and increased chemotactic responses during cell migration.

  19. Procontractile G protein–mediated signaling pathways antagonistically regulate smooth muscle differentiation in vascular remodeling

    PubMed Central

    Althoff, Till F.; Juárez, Julián Albarrán; Troidl, Kerstin; Tang, Cong; Wang, Shengpeng; Wirth, Angela; Takefuji, Mikito; Wettschureck, Nina

    2012-01-01

    Vascular smooth muscle (Sm) cells (VSMCs) are highly plastic. Their differentiation state can be regulated by serum response factor (SRF), which activates genes involved in Sm differentiation and proliferation by recruiting cofactors, such as members of the myocardin family and ternary complex factors (TCFs), respectively. However, the extracellular cues and upstream signaling mechanisms regulating SRF-dependent VSMC differentiation under in vivo conditions are poorly understood. In this study, we show that the procontractile signaling pathways mediated by the G proteins G12/G13 and Gq/G11 antagonistically regulate VSMC plasticity in different models of vascular remodeling. In mice lacking Gα12/Gα13 or their effector, the RhoGEF protein LARG, RhoA-dependent SRF-regulation was blocked and down-regulation of VSMC differentiation marker genes was enhanced. This was accompanied by an excessive vascular remodeling and exacerbation of atherosclerosis. In contrast, Sm-specific Gαq/Gα11 deficiency blocked activation of extracellular signal-regulated kinase 1/2 and the TCF Elk-1, resulting in a reduced VSMC dedifferentiation in response to flow cessation or vascular injury. These data show that the balanced activity of both G protein–mediated pathways in VSMCs is required for an appropriate vessel remodeling response in vascular diseases and suggest new approaches to modulate Sm differentiation in vascular pathologies. PMID:23129751

  20. Arl13b regulates Shh signaling from both inside and outside the cilium

    PubMed Central

    Mariani, Laura E.; Bijlsma, Maarten F.; Ivanova, Anna I.; Suciu, Sarah K.; Kahn, Richard A.; Caspary, Tamara

    2016-01-01

    The regulatory GTPase Arl13b localizes to primary cilia, where it regulates Sonic hedgehog (Shh) signaling. Missense mutations in ARL13B can cause the ciliopathy Joubert syndrome (JS), and the mouse null allele is embryonic lethal. We used mouse embryonic fibroblasts as a system to determine the effects of Arl13b mutations on Shh signaling. We tested seven different mutants—three JS-causing variants, two point mutants predicted to alter guanine nucleotide handling, one that disrupts cilia localization, and one that prevents palmitoylation and thus membrane binding—in assays of transcriptional and nontranscriptional Shh signaling. We found that mutations disrupting Arl13b’s palmitoylation site, cilia localization signal, or GTPase handling altered the Shh response in distinct assays of transcriptional or nontranscriptional signaling. In contrast, JS-causing mutations in Arl13b did not affect Shh signaling in these same assays, suggesting that these mutations result in more subtle defects, likely affecting only a subset of signaling outputs. Finally, we show that restricting Arl13b from cilia interferes with its ability to regulate Shh-stimulated chemotaxis, despite previous evidence that cilia themselves are not required for this nontranscriptional Shh response. This points to a more complex relationship between the ciliary and nonciliary roles of this regulatory GTPase than previously envisioned. PMID:27682584

  1. Insulin signaling in Caenorhabditis elegans regulates both endocrine-like and cell-autonomous outputs.

    PubMed

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

    2007-03-15

    In C. elegans, insulin signaling affects development, lifespan and stress resistance. Several studies have shown that insulin signaling affects lifespan in an endocrine-like manner from different cells, while the major downstream target of insulin, the FOXO transcription factor encoded by daf-16, may act preferentially in intestinal cells to prolong lifespan. This discrepancy raised the possibility that insulin may have both endocrine and cell-intrinsic outputs. Here, we further investigated the types of cells capable of producing endocrine outputs of insulin and also identified a new cell-intrinsic insulin output. We found that insulin signaling within groups of neurons promoted wildtype lifespan, showing that the endocrine outputs of insulin were not restricted to specific cells. In contrast, DAF-16 appeared to have a greater effect on lifespan when expressed in a combination of tissues. These results suggest that insulin signaling may regulate DAF-16 through cell-intrinsic and endocrine pathways. We also found that an insulin-dependent response to fasting in intestinal cells was preferentially regulated by intestinal insulin signaling and was less responsive to insulin signaling from non-intestinal cells. Together, these results show that C. elegans insulin signaling has endocrine as well as tissue-specific outputs which could influence lifespan in a combinatorial fashion.

  2. Intracellular calcium signals regulate growth of hepatic stellate cells via specific effects on cell cycle progression.

    PubMed

    Soliman, Elwy M; Rodrigues, Michele Angela; Gomes, Dawidson Assis; Sheung, Nina; Yu, Jin; Amaya, Maria Jimina; Nathanson, Michael H; Dranoff, Jonathan A

    2009-03-01

    Hepatic stellate cells (HSC) are important mediators of liver fibrosis. Hormones linked to downstream intracellular Ca(2+) signals upregulate HSC proliferation, but the mechanisms by which this occurs are unknown. Nuclear and cytosolic Ca(2+) signals may have distinct effects on cell proliferation, so we expressed plasmid and adenoviral constructs containing the Ca(2+) chelator parvalbumin (PV) linked to either a nuclear localization sequence (NLS) or a nuclear export sequence (NES) to block Ca(2+) signals in distinct compartments within LX-2 immortalized human HSC and primary rat HSC. PV-NLS and PV-NES constructs each targeted to the appropriate intracellular compartment and blocked Ca(2+) signals only within that compartment. PV-NLS and PV-NES constructs inhibited HSC growth. Furthermore, blockade of nuclear or cytosolic Ca(2+) signals arrested growth at the G2/mitosis (G2/M) cell-cycle interface and prevented the onset of mitosis. Blockade of nuclear or cytosolic Ca(2+) signals downregulated phosphorylation of the G2/M checkpoint phosphatase Cdc25C. Inhibition of calmodulin kinase II (CaMK II) had identical effects on LX-2 growth and Cdc25C phosphorylation. We propose that nuclear and cytosolic Ca(2+) are critical signals that regulate HSC growth at the G2/M checkpoint via CaMK II-mediated regulation of Cdc25C phosphorylation. These data provide a new logical target for pharmacological thera