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Sample records for acid signaling pathways

  1. Piperazic acid derivatives inhibit Gli1 in Hedgehog signaling pathway.

    PubMed

    Khatra, Harleen; Kundu, Jayanta; Khan, Pragya Paramita; Duttagupta, Indranil; Pattanayak, Sankha; Sinha, Surajit

    2016-09-15

    Piperazic acid, a non-proteinogenic amino acid, found in complex secondary metabolites and peptide natural substances, has shown down regulation of Gli1 expression in Hedgehog signaling pathway in cell based assays. Further structure activity relationship study indicated that amide derivatives of piperazic acid are more potent than piperazic acid itself, with little to no toxicity. However, other cellular components involved in the pathway were not affected. To the best of our knowledge, this is the first report on the inhibitory property of piperazic acid in this pathway. Hence, this molecule could serve as a useful tool for studying Hedgehog signaling. PMID:27528433

  2. Retinoic acid suppresses the canonical Wnt signaling pathway in embryonic stem cells and activates the noncanonical Wnt signaling pathway

    PubMed Central

    Osei-Sarfo, Kwame; Gudas, Lorraine J.

    2014-01-01

    Embryonic stem cells (ESCs) have both the ability to self-renew and to differentiate into various cell lineages. Retinoic acid (RA), a metabolite of Vitamin A, has a critical function in initiating lineage differentiation of ESCs through binding to the retinoic acid receptors (RARs). Additionally, the Wnt signaling pathway plays a role in pluripotency and differentiation, depending on the activation status of the canonical and noncanonical pathways. The activation of the canonical Wnt signaling pathway, which requires the nuclear accumulation of β-catenin and its interaction with Tcf1/Lef at Wnt response elements, is involved in ESC stemness maintenance. The noncanonical Wnt signaling pathway, through actions of Tcf3, can antagonize the canonical pathway. We show that RA activates the noncanonical Wnt signaling pathway, while concomitantly inhibiting the canonical pathway. RA increases the expression of ligands and receptors of the noncanonical Wnt pathway (Wnt 5a, 7a, Fzd2 and Fzd6), downstream signaling, and Tcf3 expression. RA reduces the phosphorylated β-catenin level by 4-fold, though total β-catenin levels don't change. We show that RA signaling increases the dissociation of Tcf1 and the association of Tcf3 at promoters of genes that regulate stemness (e.g. NR5A2,Lrh-1) or differentiation (eg. Cyr61, Zic5). Knockdown of Tcf3 increases Lrh-1 transcript levels in mESCs and prevents the RA-associated, ∼4-fold increase in Zic5, indicating that RA requires Tcf3 to effect changes in Zic5 levels. We demonstrate a novel role for RA in altering the activation of these two Wnt signaling pathways and show that Tcf3 mediates some actions of RA during differentiation. PMID:24648413

  3. Arabidopsis leaf necrosis caused by simulated acid rain is related to the salicylic acid signaling pathway.

    PubMed

    Lee, Youngmi; Park, Jongbum; Im, Kyunghoan; Kim, Kiyoon; Lee, Jungwoo; Lee, Kyungyeoll; Park, Jung-An; Lee, Taek-Kyun; Park, Dae-Sup; Yang, Joo-Sung; Kim, Donggiun; Lee, Sukchan

    2006-01-01

    Arabidopsis leaves treated with simulated acid rain (SiAR) showed phenotypes similar to necrotic lesions caused by biotic stresses like Pseudomonad infiltration. Exposure of Arabidopsis to SiAR resulted in the up-regulation of genes known to be induced by the salicylic acid (SA)-mediated pathogen resistance response. The expression of enhanced disease susceptibility (EDS), nonexpressor of PR (NPR) and pathogen-related 1 (PR1), all of which are involved in the salicylic acid signaling pathway, were increased after SiAR exposure. However, vegetative storage protein (VSP), a member of the jasmonic acid pathway did not show a significant change in transcript level. SiAR treatment of transgenic plants expressing salicylate hydroxylase (Nah-G), which prevents the accumulation of salicylic acid, underwent more extensive necrosis than wild-type plants, indicating that the signaling pathway activated by SiAR may overlap with the SA-dependent, systemic acquired resistance pathway. Both Col-0 and Nah-G plants showed sensitivity to SiAR and sulfuric SiAR (S-SiAR) by developing necrotic lesions. Neither Col-0 plants nor Nah-G plants showed sensitivity to nitric SiAR (N-SiAR). These results suggest that SiAR activates at least the salicylic acid pathway and activation of this pathway is sensitive to sulfuric acid.

  4. Docosahexaenoic acid and signaling pathways in rabbit colon.

    PubMed

    Calderaro, V; Parrillo, C; Balestrieri, M L; Giovane, A; Filippelli, A; Rossi, F

    1994-04-01

    The effects of one of the main components of fish oil, docosahexaenoic acid (DHA), on prostaglandin (PG) and Ca2+ signaling pathways were examined in intact mucosa and freshly isolated crypt cells of rabbit descending colon. Preincubation of serosal mucosa for 20 min with 1 microM DHA fully suppressed the short-circuit and transepithelial conductance increase induced by serosal addition of 10 microM arachidonic acid (AA). DHA at 1 microM also prevented the Cl- secretion promoted by 10 microM AA, as estimated by unidirectional 36Cl flux measurements (net flux = 0.68 +/- 0.30 versus -1.91 +/- 0.20 microEq/hr/cm2, four experiments, p < 0.001), whereas it did not affect the electrophysiological and ion flux responses to PGE2. Addition of 1 microM DHA to the serosal side of the mucosa also inhibited the PG cascade activation elicited by AA (PG synthesis and second messenger cAMP increase). In vitro assays of colonic cyclooxygenase activity showed that 1 microM DHA inhibited (with a 20-min lag) cyclooxygenase activity to the same extent as 5 microM indomethacin (approximately 82% and 80%, respectively). DHA also affected the Ca2+ signaling pathway; in isolated crypt cells, the cytosolic free Ca2+ concentration ([Ca2+]i) dropped by 49 +/- 7.6% (mean +/- standard error, six experiments) after incubation with 1 microM DHA. The sustained phase of the [Ca2+]i response to 500 nM concentrations of the intracellular Ca(2+)-ATPase inhibitor thapsigargin was also inhibited within 150 sec upon 1 microM DHA addition (141 +/- 5.8 versus 243 +/- 8.2 nM [Ca2+]i mean +/- standard error, eight experiments, p < 0.01). The [Ca2+]i-lowering effect of DHA, which was not achieved by incubation with other free fatty acids, was not prevented by removal of Na+ from the incubation medium (-46 +/- 4.3% versus -47 +/- 3.8%, mean +/- standard error, four experiments), nor it was mediated by cAMP-, protein kinase C-, or calmodulin-dependent mechanisms. The incubation of highly purified basolateral

  5. Enhancement of arachidonic acid signaling pathway by nicotinic acid receptor HM74A

    SciTech Connect

    Tang, Yuting . E-mail: ytang@prdus.jnj.com; Zhou, Lubing; Gunnet, Joseph W.; Wines, Pamela G.; Cryan, Ellen V.; Demarest, Keith T.

    2006-06-23

    HM74A is a G protein-coupled receptor for nicotinic acid (niacin), which has been used clinically to treat dyslipidemia for decades. The molecular mechanisms whereby niacin exerts its pleiotropic effects on lipid metabolism remain largely unknown. In addition, the most common side effect in niacin therapy is skin flushing that is caused by prostaglandin release, suggesting that the phospholipase A{sub 2} (PLA{sub 2})/arachidonic acid (AA) pathway is involved. Various eicosanoids have been shown to activate peroxisome-proliferator activated receptors (PPAR) that play a diverse array of roles in lipid metabolism. To further elucidate the potential roles of HM74A in mediating the therapeutic effects and/or side effects of niacin, we sought to explore the signaling events upon HM74A activation. Here we demonstrated that HM74A synergistically enhanced UTP- and bradykinin-mediated AA release in a pertussis toxin-sensitive manner in A431 cells. Activation of HM74A also led to Ca{sup 2+}-mobilization and enhanced bradykinin-promoted Ca{sup 2+}-mobilization through Gi protein. While HM74A increased ERK1/2 activation by the bradykinin receptor, it had no effects on UTP-promoted ERK1/2 activation.Furthermore, UTP- and bradykinin-mediated AA release was significantly decreased in the presence of both MAPK kinase inhibitor PD 098059 and PKC inhibitor GF 109203X. However, the synergistic effects of HM74A were not dramatically affected by co-treatment with both inhibitors, indicating the cross-talk occurred at the receptor level. Finally, stimulation of A431 cells transiently transfected with PPRE-luciferase with AA significantly induced luciferase activity, mimicking the effects of PPAR{gamma} agonist rosiglitazone, suggesting that alteration of AA signaling pathway can regulate gene expression via endogenous PPARs.

  6. Microbial effectors target multiple steps in the salicylic acid production and signaling pathway

    PubMed Central

    Tanaka, Shigeyuki; Han, Xiaowei; Kahmann, Regine

    2015-01-01

    Microbes attempting to colonize plants are recognized through the plant immune surveillance system. This leads to a complex array of global as well as specific defense responses, which are often associated with plant cell death and subsequent arrest of the invader. The responses also entail complex changes in phytohormone signaling pathways. Among these, salicylic acid (SA) signaling is an important pathway because of its ability to trigger plant cell death. As biotrophic and hemibiotrophic pathogens need to invade living plant tissue to cause disease, they have evolved efficient strategies to downregulate SA signaling by virulence effectors, which can be proteins or secondary metabolites. Here we review the strategies prokaryotic pathogens have developed to target SA biosynthesis and signaling, and contrast this with recent insights into how plant pathogenic eukaryotic fungi and oomycetes accomplish the same goal. PMID:26042138

  7. Phospholipase D Signaling Pathways and Phosphatidic Acid as Therapeutic Targets in Cancer

    PubMed Central

    Bruntz, Ronald C.; Lindsley, Craig W.

    2014-01-01

    Phospholipase D is a ubiquitous class of enzymes that generates phosphatidic acid as an intracellular signaling species. The phospholipase D superfamily plays a central role in a variety of functions in prokaryotes, viruses, yeast, fungi, plants, and eukaryotic species. In mammalian cells, the pathways modulating catalytic activity involve a variety of cellular signaling components, including G protein–coupled receptors, receptor tyrosine kinases, polyphosphatidylinositol lipids, Ras/Rho/ADP-ribosylation factor GTPases, and conventional isoforms of protein kinase C, among others. Recent findings have shown that phosphatidic acid generated by phospholipase D plays roles in numerous essential cellular functions, such as vesicular trafficking, exocytosis, autophagy, regulation of cellular metabolism, and tumorigenesis. Many of these cellular events are modulated by the actions of phosphatidic acid, and identification of two targets (mammalian target of rapamycin and Akt kinase) has especially highlighted a role for phospholipase D in the regulation of cellular metabolism. Phospholipase D is a regulator of intercellular signaling and metabolic pathways, particularly in cells that are under stress conditions. This review provides a comprehensive overview of the regulation of phospholipase D activity and its modulation of cellular signaling pathways and functions. PMID:25244928

  8. Salicylic acid induces vanillin synthesis through the phospholipid signaling pathway in Capsicum chinense cell cultures.

    PubMed

    Rodas-Junco, Beatriz A; Cab-Guillén, Yahaira; Muñoz-Sánchez, J Armando; Vázquez-Flota, Felipe; Monforte-González, Miriam; Hernández-Sotomayor, S M Teresa

    2013-10-01

    Signal transduction via phospholipids is mediated by phospholipases such as phospholipase C (PLC) and D (PLD), which catalyze hydrolysis of plasma membrane structural phospholipids. Phospholipid signaling is also involved in plant responses to phytohormones such as salicylic acid (SA). The relationships between phospholipid signaling, SA, and secondary metabolism are not fully understood. Using a Capsicum chinense cell suspension as a model, we evaluated whether phospholipid signaling modulates SA-induced vanillin production through the activation of phenylalanine ammonia lyase (PAL), a key enzyme in the biosynthetic pathway. Salicylic acid was found to elicit PAL activity and consequently vanillin production, which was diminished or reversed upon exposure to the phosphoinositide-phospholipase C (PI-PLC) signaling inhibitors neomycin and U73122. Exposure to the phosphatidic acid inhibitor 1-butanol altered PLD activity and prevented SA-induced vanillin production. Our results suggest that PLC and PLD-generated secondary messengers may be modulating SA-induced vanillin production through the activation of key biosynthetic pathway enzymes.

  9. Opposing effects of bile acids deoxycholic acid and ursodeoxycholic acid on signal transduction pathways in oesophageal cancer cells.

    PubMed

    Abdel-Latif, Mohamed M; Inoue, Hiroyasu; Reynolds, John V

    2016-09-01

    Ursodeoxycholic acid (UDCA) was reported to reduce bile acid toxicity, but the mechanisms underlying its cytoprotective effects are not fully understood. The aim of the present study was to examine the effects of UDCA on the modulation of deoxycholic acid (DCA)-induced signal transduction in oesophageal cancer cells. Nuclear factor-κB (NF-κB) and activator protein-1 (AP-1) activity was assessed using a gel shift assay. NF-κB activation and translocation was performed using an ELISA-based assay and immunofluorescence analysis. COX-2 expression was analysed by western blotting and COX-2 promoter activity was assessed by luciferase assay. DCA induced NF-κB and AP-1 DNA-binding activities in SKGT-4 and OE33 cells. UDCA pretreatment inhibited DCA-induced NF-κB and AP-1 activation and NF-κB translocation. This inhibitory effect was coupled with a blockade of IκB-α degradation and inhibition of phosphorylation of IKK-α/β and ERK1/2. Moreover, UDCA pretreatment inhibited COX-2 upregulation. Using transient transfection of the COX-2 promoter, UDCA pretreatment abrogated DCA-induced COX-2 promoter activation. In addition, UDCA protected oesophageal cells from the apoptotic effects of deoxycholate. Our findings indicate that UDCA inhibits DCA-induced signalling pathways in oesophageal cancer cells. These data indicate a possible mechanistic role for the chemopreventive actions of UDCA in oesophageal carcinogenesis.

  10. Chemical genetics reveals negative regulation of abscisic acid signaling by a plant immune response pathway.

    PubMed

    Kim, Tae-Houn; Hauser, Felix; Ha, Tracy; Xue, Shaowu; Böhmer, Maik; Nishimura, Noriyuki; Munemasa, Shintaro; Hubbard, Katharine; Peine, Nora; Lee, Byeong-Ha; Lee, Stephen; Robert, Nadia; Parker, Jane E; Schroeder, Julian I

    2011-06-01

    Coordinated regulation of protection mechanisms against environmental abiotic stress and pathogen attack is essential for plant adaptation and survival. Initial abiotic stress can interfere with disease-resistance signaling [1-6]. Conversely, initial plant immune signaling may interrupt subsequent abscisic acid (ABA) signal transduction [7, 8]. However, the processes involved in this crosstalk between these signaling networks have not been determined. By screening a 9600-compound chemical library, we identified a small molecule [5-(3,4-dichlorophenyl)furan-2-yl]-piperidine-1-ylmethanethione (DFPM) that rapidly downregulates ABA-dependent gene expression and also inhibits ABA-induced stomatal closure. Transcriptome analyses show that DFPM also stimulates expression of plant defense-related genes. Major early regulators of pathogen-resistance responses, including EDS1, PAD4, RAR1, and SGT1b, are required for DFPM-and notably also for Pseudomonas-interference with ABA signal transduction, whereas salicylic acid, EDS16, and NPR1 are not necessary. Although DFPM does not interfere with early ABA perception by PYR/RCAR receptors or ABA activation of SnRK2 kinases, it disrupts cytosolic Ca(2+) signaling and downstream anion channel activation in a PAD4-dependent manner. Our findings provide evidence that activation of EDS1/PAD4-dependent plant immune responses rapidly disrupts ABA signal transduction and that this occurs at the level of Ca(2+) signaling, illuminating how the initial biotic stress pathway interferes with ABA signaling.

  11. Drosophila fatty acid taste signals through the PLC pathway in sugar-sensing neurons.

    PubMed

    Masek, Pavel; Keene, Alex C

    2013-01-01

    Taste is the primary sensory system for detecting food quality and palatability. Drosophila detects five distinct taste modalities that include sweet, bitter, salt, water, and the taste of carbonation. Of these, sweet-sensing neurons appear to have utility for the detection of nutritionally rich food while bitter-sensing neurons signal toxicity and confer repulsion. Growing evidence in mammals suggests that taste for fatty acids (FAs) signals the presence of dietary lipids and promotes feeding. While flies appear to be attracted to fatty acids, the neural basis for fatty acid detection and attraction are unclear. Here, we demonstrate that a range of FAs are detected by the fly gustatory system and elicit a robust feeding response. Flies lacking olfactory organs respond robustly to FAs, confirming that FA attraction is mediated through the gustatory system. Furthermore, flies detect FAs independent of pH, suggesting the molecular basis for FA taste is not due to acidity. We show that low and medium concentrations of FAs serve as an appetitive signal and they are detected exclusively through the same subset of neurons that sense appetitive sweet substances, including most sugars. In mammals, taste perception of sweet and bitter substances is dependent on phospholipase C (PLC) signaling in specialized taste buds. We find that flies mutant for norpA, a Drosophila ortholog of PLC, fail to respond to FAs. Intriguingly, norpA mutants respond normally to other tastants, including sucrose and yeast. The defect of norpA mutants can be rescued by selectively restoring norpA expression in sweet-sensing neurons, corroborating that FAs signal through sweet-sensing neurons, and suggesting PLC signaling in the gustatory system is specifically involved in FA taste. Taken together, these findings reveal that PLC function in Drosophila sweet-sensing neurons is a conserved molecular signaling pathway that confers attraction to fatty acids.

  12. Phosphatidic acid mediates activation of mTORC1 through the ERK signaling pathway

    PubMed Central

    Winter, Jeremiah N.; Fox, Todd E.; Kester, Mark; Jefferson, Leonard S.

    2010-01-01

    The mammalian target of rapamycin (mTOR) assembles into two distinct multiprotein complexes known as mTORC1 and mTORC2. Of the two complexes, mTORC1 acts to integrate a variety of positive and negative signals to downstream targets that regulate cell growth. The lipid second messenger, phosphatidic acid (PA), represents one positive input to mTORC1, and it is thought to act by binding directly to mTOR, thereby enhancing the protein kinase activity of mTORC1. Support for this model includes findings that PA binds directly to mTOR and addition of PA to the medium of cells in culture results in activation of mTORC1. In contrast, the results of the present study do not support a model in which PA activates mTORC1 through direct interaction with the protein kinase but, instead, show that the lipid promotes mTORC1 signaling through activation of the ERK pathway. Moreover, rather than acting directly on mTORC1, the results suggest that exogenous PA must be metabolized to lysophosphatidic acid (LPA), which subsequently activates the LPA receptor endothelial differentiation gene (EDG-2). Finally, in contrast to previous studies, the results of the present study demonstrate that leucine does not act through phospholipase D and PA to activate mTORC1 and, instead, show that the two mediators act through parallel upstream signaling pathways to activate mTORC1. Overall, the results demonstrate that leucine and PA signal through parallel pathways to activate mTORC1 and that PA mediates its effect through the ERK pathway, rather than through direct binding to mTOR. PMID:20427710

  13. Early mouse caudal development relies on crosstalk between retinoic acid, Shh and Fgf signalling pathways.

    PubMed

    Ribes, Vanessa; Le Roux, Isabelle; Rhinn, Muriel; Schuhbaur, Brigitte; Dollé, Pascal

    2009-02-01

    The progressive generation of embryonic trunk structures relies on the proper patterning of the caudal epiblast, which involves the integration of several signalling pathways. We have investigated the function of retinoic acid (RA) signalling during this process. We show that, in addition to posterior mesendoderm, primitive streak and node cells transiently express the RA-synthesizing enzyme Raldh2 prior to the headfold stage. RA-responsive cells (detected by the RA-activated RARE-lacZ transgene) are additionally found in the epiblast layer. Analysis of RA-deficient Raldh2(-/-) mutants reveals early caudal patterning defects, with an expansion of primitive streak and mesodermal markers at the expense of markers of the prospective neuroepithelium. As a result, many genes involved in neurogenesis and/or patterning of the embryonic spinal cord are affected in their expression. We demonstrate that RA signalling is required at late gastrulation stages for mesodermal and neural progenitors to respond to the Shh signal. Whole-embryo culture experiments indicate that the proper response of cells to Shh requires two RA-dependent mechanisms: (1) a balanced antagonism between Fgf and RA signals, and (2) a RA-mediated repression of Gli2 expression. Thus, an interplay between RA, Fgf and Shh signalling is likely to be an important mechanism underpinning the tight regulation of caudal embryonic development. PMID:19168680

  14. FOXP2 drives neuronal differentiation by interacting with retinoic acid signaling pathways

    PubMed Central

    Devanna, Paolo; Middelbeek, Jeroen; Vernes, Sonja C.

    2014-01-01

    FOXP2 was the first gene shown to cause a Mendelian form of speech and language disorder. Although developmentally expressed in many organs, loss of a single copy of FOXP2 leads to a phenotype that is largely restricted to orofacial impairment during articulation and linguistic processing deficits. Why perturbed FOXP2 function affects specific aspects of the developing brain remains elusive. We investigated the role of FOXP2 in neuronal differentiation and found that FOXP2 drives molecular changes consistent with neuronal differentiation in a human model system. We identified a network of FOXP2 regulated genes related to retinoic acid signaling and neuronal differentiation. FOXP2 also produced phenotypic changes associated with neuronal differentiation including increased neurite outgrowth and reduced migration. Crucially, cells expressing FOXP2 displayed increased sensitivity to retinoic acid exposure. This suggests a mechanism by which FOXP2 may be able to increase the cellular differentiation response to environmental retinoic acid cues for specific subsets of neurons in the brain. These data demonstrate that FOXP2 promotes neuronal differentiation by interacting with the retinoic acid signaling pathway and regulates key processes required for normal circuit formation such as neuronal migration and neurite outgrowth. In this way, FOXP2, which is found only in specific subpopulations of neurons in the brain, may drive precise neuronal differentiation patterns and/or control localization and connectivity of these FOXP2 positive cells. PMID:25309332

  15. FOXP2 drives neuronal differentiation by interacting with retinoic acid signaling pathways.

    PubMed

    Devanna, Paolo; Middelbeek, Jeroen; Vernes, Sonja C

    2014-01-01

    FOXP2 was the first gene shown to cause a Mendelian form of speech and language disorder. Although developmentally expressed in many organs, loss of a single copy of FOXP2 leads to a phenotype that is largely restricted to orofacial impairment during articulation and linguistic processing deficits. Why perturbed FOXP2 function affects specific aspects of the developing brain remains elusive. We investigated the role of FOXP2 in neuronal differentiation and found that FOXP2 drives molecular changes consistent with neuronal differentiation in a human model system. We identified a network of FOXP2 regulated genes related to retinoic acid signaling and neuronal differentiation. FOXP2 also produced phenotypic changes associated with neuronal differentiation including increased neurite outgrowth and reduced migration. Crucially, cells expressing FOXP2 displayed increased sensitivity to retinoic acid exposure. This suggests a mechanism by which FOXP2 may be able to increase the cellular differentiation response to environmental retinoic acid cues for specific subsets of neurons in the brain. These data demonstrate that FOXP2 promotes neuronal differentiation by interacting with the retinoic acid signaling pathway and regulates key processes required for normal circuit formation such as neuronal migration and neurite outgrowth. In this way, FOXP2, which is found only in specific subpopulations of neurons in the brain, may drive precise neuronal differentiation patterns and/or control localization and connectivity of these FOXP2 positive cells.

  16. Changes in actin dynamics are involved in salicylic acid signaling pathway.

    PubMed

    Matoušková, Jindřiška; Janda, Martin; Fišer, Radovan; Sašek, Vladimír; Kocourková, Daniela; Burketová, Lenka; Dušková, Jiřina; Martinec, Jan; Valentová, Olga

    2014-06-01

    Changes in actin cytoskeleton dynamics are one of the crucial players in many physiological as well as non-physiological processes in plant cells. Positioning of actin filament arrays is necessary for successful establishment of primary lines of defense toward pathogen attack, depolymerization leads very often to the enhanced susceptibility to the invading pathogen. On the other hand it was also shown that the disruption of actin cytoskeleton leads to the induction of defense response leading to the expression of PATHOGENESIS RELATED proteins (PR). In this study we show that pharmacological actin depolymerization leads to the specific induction of genes in salicylic acid pathway but not that involved in jasmonic acid signaling. Life imaging of leafs of Arabidopsis thaliana with GFP-tagged fimbrin (GFP-fABD2) treated with 1 mM salicylic acid revealed rapid disruption of actin filaments resembling the pattern viewed after treatment with 200 nM latrunculin B. The effect of salicylic acid on actin filament fragmentation was prevented by exogenous addition of phosphatidic acid, which binds to the capping protein and thus promotes actin polymerization. The quantitative evaluation of actin filament dynamics is also presented.

  17. Streptozotocin induced activation of oxidative stress responsive splenic cell signaling pathways: Protective role of arjunolic acid

    SciTech Connect

    Manna, Prasenjit; Ghosh, Jyotirmoy; Das, Joydeep

    2010-04-15

    Present study investigates the beneficial role of arjunolic acid (AA) against the alteration in the cytokine levels and simultaneous activation of oxidative stress responsive signaling pathways in spleen under hyperglycemic condition. Diabetes was induced by injection of streptozotocin (STZ) (at a dose of 70 mg/kg body weight, injected in the tail vain). STZ administration elevated the levels of IL-2 as well as IFN-gamma and attenuated the level of TNF-alpha in the sera of diabetic animals. In addition, hyperglycemia is also associated with the increased production of intracellular reactive intermediates resulting with the elevation in lipid peroxidation, protein carbonylation and reduction in intracellular antioxidant defense. Investigating the oxidative stress responsive cell signaling pathways, increased expressions (immunoreactive concentrations) of phosphorylated p65 as well as its inhibitor protein phospho IkappaBalpha and phosphorylated mitogen activated protein kinases (MAPKs) have been observed in diabetic spleen tissue. Studies on isolated splenocytes revealed that hyperglycemia caused disruption of mitochondrial membrane potential, elevation in the concentration of cytosolic cytochrome c as well as activation of caspase 3 leading to apoptotic cell death. Histological examination revealed that diabetic induction depleted the white pulp scoring which is in agreement with the reduced immunological response. Treatment with AA prevented the hyperglycemia and its associated pathogenesis in spleen tissue. Results suggest that AA might act as an anti-diabetic and immunomodulatory agent against hyperglycemia.

  18. Salvianolic Acid B Attenuates Experimental Pulmonary Fibrosis through Inhibition of the TGF-β Signaling Pathway

    PubMed Central

    Liu, Qingmei; Chu, Haiyan; Ma, Yanyun; Wu, Ting; Qian, Feng; Ren, Xian; Tu, Wenzhen; Zhou, Xiaodong; Jin, Li; Wu, Wenyu; Wang, Jiucun

    2016-01-01

    Pulmonary fibrosis is a progressive and fatal disorder. In our previous study, we found that the Yiqihuoxue formula (YQHX), a prescription of Traditional Chinese Medicine, had a curative effect on scleroderma, a typical fibrotic disease. The aim of this study was to determine the key ingredient mediating the therapeutic effects of YQHX and to examine its effect on pulmonary fibrosis, including its mechanism. Luciferase reporter assays showed that the most important anti-fibrotic component of the YQHX was Salviae miltiorrhiza (SM). Experiments performed using a bleomycin-instilled mouse model of pulmonary fibrosis showed that Salvianolic acid B (SAB), the major ingredient of SM, had strong anti-inflammatory and anti-fibrotic effects through its inhibition of inflammatory cell infiltration, alveolar structure disruption, and collagen deposition. Furthermore, SAB suppressed TGF-β-induced myofibroblastic differentiation of MRC-5 fibroblasts and TGF-β-mediated epithelial-to-mesenchymal transition of A549 cells by inhibiting both Smad-dependent signaling and the Smad-independent MAPK pathway. Taken together, our results suggest that SM is the key anti-fibrotic component of the YQHX and that SAB, the major ingredient of SM, alleviates experimental pulmonary fibrosis both in vivo and in vitro by inhibiting the TGF-β signaling pathway. Together, these results suggest that SAB potently inhibits pulmonary fibrosis. PMID:27278104

  19. Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress.

    PubMed

    Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

    2016-02-01

    The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter

  20. Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress

    PubMed Central

    Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

    2016-01-01

    The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter

  1. Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress.

    PubMed

    Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

    2016-02-01

    The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter

  2. Impact of Arachidonic Acid and the Leukotriene Signaling Pathway on Vasculogenesis of Mouse Embryonic Stem Cells.

    PubMed

    Huang, Yu-Han; Sharifpanah, Fatemeh; Becker, Sven; Wartenberg, Maria; Sauer, Heinrich

    2016-01-01

    Embryonic stem (ES) cells can differentiate into various kinds of cells, such as endothelial and hematopoietic cells. In addition, some evidence suggests that inflammatory mediators such as leukotrienes (LTs), which include the 5-lipoxygenase (LOX) family, can regulate endothelial cell differentiation. In the present study, the eicosanoid precursor arachidonic acid (AA) stimulated vasculogenesis of ES cells by increasing the number of fetal liver kinase-1+ vascular progenitor cells as well as vascular structures positive for platelet endothelial cell adhesion protein-1 and vascular endothelial cadherin. The stimulation of vasculogenesis and expression of the rate-limiting enzyme in the LT signaling pathway, 5-LOX-activating protein (FLAP), was blunted upon treatment with the FLAP inhibitors AM643 and REV5901. Vasculogenesis was significantly restored upon exogenous addition of LTs. Downstream of FLAP, the LTB4 receptor (BLT1) blocker U75302, the BLT2 receptor blocker LY255283 as well as the cysteinyl LT blocker BAY-u9773 inhibited vasculogenesis of ES cells. AA treatment of differentiating ES cells increased reactive oxygen species (ROS) generation, which was not affected upon either FLAP or cyclooxygenase-2 inhibition. Prevention of ROS generation by either the free radical scavengers vitamin E and N-(2-mercaptopropionyl)glycine or the NADPH oxidase inhibitor VAS2870 downregulated vasculogenesis of ES cells and blunted the provasculogenic effect of AA. In summary, our data demonstrate that proinflammatory AA stimulates vasculogenesis of ES cells via the LT pathway by mechanisms involving ROS generation. PMID:27198524

  3. Regulation of Abscisic Acid Signaling by the Ethylene Response Pathway in Arabidopsis

    PubMed Central

    Ghassemian, Majid; Nambara, Eiji; Cutler, Sean; Kawaide, Hiroshi; Kamiya, Yuji; McCourt, Peter

    2000-01-01

    Although abscisic acid (ABA) is involved in a variety of plant growth and developmental processes, few genes that actually regulate the transduction of the ABA signal into a cellular response have been identified. In an attempt to determine negative regulators of ABA signaling, we identified mutants, designated enhanced response to ABA3 (era3), that increased the sensitivity of the seed to ABA. Biochemical and molecular analyses demonstrated that era3 mutants overaccumulate ABA, suggesting that era3 is a negative regulator of ABA synthesis. Subsequent genetic analysis of era3 alleles, however, showed that these are new alleles at the ETHYLENE INSENSITIVE2 locus. Other mutants defective in their response to ethylene also showed altered ABA sensitivity; from these results, we conclude that ethylene appears to be a negative regulator of ABA action during germination. In contrast, the ethylene response pathway positively regulates some aspects of ABA action that involve root growth in the absence of ethylene. We discuss the response of plants to ethylene and ABA in the context of how these two hormones could influence the same growth responses. PMID:10899978

  4. Chitosan oligosaccharide induces resistance to Tobacco mosaic virus in Arabidopsis via the salicylic acid-mediated signalling pathway.

    PubMed

    Jia, Xiaochen; Meng, Qingshan; Zeng, Haihong; Wang, Wenxia; Yin, Heng

    2016-01-01

    Chitosan is one of the most abundant carbohydrate biopolymers in the world, and chitosan oligosaccharide (COS), which is prepared from chitosan, is a plant immunity regulator. The present study aimed to validate the effect of COS on inducing resistance to tobacco mosaic virus (TMV) in Arabidopsis and to investigate the potential defence-related signalling pathways involved. Optimal conditions for the induction of TMV resistance in Arabidopsis were COS pretreatment at 50 mg/L for 1 day prior to inoculation with TMV. Multilevel indices, including phenotype data, and TMV coat protein expression, revealed that COS induced TMV resistance in wild-type and jasmonic acid pathway- deficient (jar1) Arabidopsis plants, but not in salicylic acid pathway deficient (NahG) Arabidopsis plants. Quantitative-PCR and analysis of phytohormone levels confirmed that COS pretreatment enhanced the expression of the defence-related gene PR1, which is a marker of salicylic acid signalling pathway, and increased the amount of salicylic acid in WT and jar1, but not in NahG plants. Taken together, these results confirm that COS induces TMV resistance in Arabidopsis via activation of the salicylic acid signalling pathway. PMID:27189192

  5. Chitosan oligosaccharide induces resistance to Tobacco mosaic virus in Arabidopsis via the salicylic acid-mediated signalling pathway

    PubMed Central

    Jia, Xiaochen; Meng, Qingshan; Zeng, Haihong; Wang, Wenxia; Yin, Heng

    2016-01-01

    Chitosan is one of the most abundant carbohydrate biopolymers in the world, and chitosan oligosaccharide (COS), which is prepared from chitosan, is a plant immunity regulator. The present study aimed to validate the effect of COS on inducing resistance to tobacco mosaic virus (TMV) in Arabidopsis and to investigate the potential defence-related signalling pathways involved. Optimal conditions for the induction of TMV resistance in Arabidopsis were COS pretreatment at 50 mg/L for 1 day prior to inoculation with TMV. Multilevel indices, including phenotype data, and TMV coat protein expression, revealed that COS induced TMV resistance in wild-type and jasmonic acid pathway- deficient (jar1) Arabidopsis plants, but not in salicylic acid pathway deficient (NahG) Arabidopsis plants. Quantitative-PCR and analysis of phytohormone levels confirmed that COS pretreatment enhanced the expression of the defence-related gene PR1, which is a marker of salicylic acid signalling pathway, and increased the amount of salicylic acid in WT and jar1, but not in NahG plants. Taken together, these results confirm that COS induces TMV resistance in Arabidopsis via activation of the salicylic acid signalling pathway. PMID:27189192

  6. Uncoupling protein 3 expression levels influence insulin sensitivity, fatty acid oxidation, and related signaling pathways.

    PubMed

    Senese, Rosalba; Valli, Vivien; Moreno, Maria; Lombardi, Assunta; Busiello, Rosa Anna; Cioffi, Federica; Silvestri, Elena; Goglia, Fernando; Lanni, Antonia; de Lange, Pieter

    2011-01-01

    Controversy exists on whether uncoupling protein 3 (UCP3) positively or negatively influences insulin sensitivity in vivo, and the underlying signaling pathways have been scarcely studied. We studied how a progressive reduction in UCP3 expression (using UCP3 +/+, UCP3 +/-, and UCP3 -/- mice) modulates insulin sensitivity and related metabolic parameters. In order to further validate our observations, we also studied animals in which insulin resistance was induced by administration of a high-fat diet (HFD). In UCP3 +/- and UCP3 -/- mice, gastrocnemius muscle Akt/protein kinase B (Akt/PKB) (serine 473) and AMP-activated protein kinase (AMPK) (threonine 171) phosphorylation, and glucose transporter 4 (GLUT4) membrane levels were reduced compared to UCP3 +/+ mice. The HOMA-IR index (insulin resistance parameter) was increased both in the UCP3 +/- and UCP3 -/- mice. In these mice, insulin administration normalized Akt/PKB phosphorylation between genotypes while AMPK phosphorylation was further reduced, and sarcolemmal GLUT4 levels were induced but did not reach control levels. Furthermore, non-insulin-stimulated muscle fatty acid oxidation and the expression of several involved genes both in muscle and in liver were reduced. HFD administration induced insulin resistance in UCP3 +/+ mice and the aforementioned parameters resulted similar to those of chow-fed UCP3 +/- and UCP3 -/- mice. In conclusion, high-fat-diet-induced insulin resistance in wild-type mice mimics that of chow-fed UCP3 +/- and UCP3 -/- mice showing that progressive reduction of UCP3 levels results in insulin resistance. This is accompanied by decreased fatty acid oxidation and a less intense Akt/PKB and AMPK signaling.

  7. Tributyltin and triphenyltin inhibit osteoclast differentiation through a retinoic acid receptor-dependent signaling pathway

    SciTech Connect

    Yonezawa, Takayuki; Hasegawa, Shin-ichi; Ahn, Jae-Yong; Cha, Byung-Yoon; Teruya, Toshiaki; Hagiwara, Hiromi; Nagai, Kazuo; Woo, Je-Tae; E-mail: jwoo@isc.chubu.ac.jp

    2007-03-30

    Organotin compounds, such as tributyltin (TBT) and triphenyltin (TPT), have been widely used in agriculture and industry. Although these compounds are known to have many toxic effects, including endocrine-disrupting effects, their effects on bone resorption are unknown. In this study, we investigated the effects of organotin compounds, such as monobutyltin (MBT), dibutyltin (DBT), TBT, and TPT, on osteoclast differentiation using mouse monocytic RAW264.7 cells. MBT and DBT had no effects, whereas TBT and TPT dose-dependently inhibited osteoclast differentiation at concentrations of 3-30 nM. Treatment with a retinoic acid receptor (RAR)-specific antagonist, Ro41-5253, restored the inhibition of osteoclastogenesis by TBT and TPT. TBT and TPT reduced receptor activator of nuclear factor-{kappa}B ligand (RANKL) induced nuclear factor of activated T cells (NFAT) c1 expression, and the reduction in NFATc1 expression was recovered by Ro41-5253. Our results suggest that TBT and TPT suppress osteoclastogenesis by inhibiting RANKL-induced NFATc1 expression via an RAR-dependent signaling pathway.

  8. Asiatic Acid Protects against Cardiac Hypertrophy through Activating AMPKα Signalling Pathway

    PubMed Central

    Ma, Zhen-Guo; Dai, Jia; Wei, Wen-Ying; Zhang, Wen-Bin; Xu, Si-Chi; Liao, Hai-Han; Yang, Zheng; Tang, Qi-Zhu

    2016-01-01

    Background: AMPactivated protein kinase α (AMPKα) is closely involved in the process of cardiac hypertrophy. Asiatic acid (AA), a pentacyclic triterpene, was found to activate AMPKα in our preliminary experiment. However, its effects on the development of cardiac hypertrophy remain unclear. The present study was to determine whether AA could protect against cardiac hypertrophy. Methods: Mice subjected to aortic banding were orally given AA (10 or 30mg/kg) for 7 weeks. In the inhibitory experiment, Compound C was intraperitoneally injected for 3 weeks after surgery. Results: Our results showed that AA markedly inhibited hypertrophic responses induced by pressure overload or angiotensin II. AA also suppressed cardiac fibrosis in vivo and accumulation of collagen in vitro. The protective effects of AA were mediated by activation of AMPKα and inhibition of the mammalian target of rapamycin (mTOR) pathway and extracellular signal-regulated kinase (ERK) in vivo and in vitro. However, AA lost the protective effects after AMPKα inhibition or gene deficiency. Conclusions: AA protects against cardiac hypertrophy by activating AMPKα, and has the potential to be used for the treatment of heart failure. PMID:27313499

  9. 15-oxoeicosatetraenoic acid is a 15-hydroxyprostaglandin dehydrogenase-derived electrophilic mediator of inflammatory signaling pathways

    PubMed Central

    Snyder, Nathaniel W.; Golin-Bisello, Franca; Gao, Yang; Blair, Ian A.; Freeman, Bruce A.; Wendell, Stacy Gelhaus

    2014-01-01

    Bioactive lipids govern cellular homeostasis and pathogenic inflammatory processes. Current dogma holds that bioactive lipids, such as prostaglandins and lipoxins, are inactivated by 15-hydroxyprostaglandin dehydrogenase (15PGDH). In contrast, the present results reveal that catabolic “inactivation” of hydroxylated polyunsaturated fatty acids (PUFAs) yields electrophilic α,β-unsaturated ketone derivatives. These endogenously produced species are chemically reactive signaling mediators that induce tissue protective events. Electrophilic fatty acids diversify the proteome through post-translational alkylation of nucleophilic cysteines in key transcriptional regulatory proteins and enzymes that govern cellular metabolic and inflammatory homeostasis. 15PGDH regulates these processes as it is responsible for the formation of numerous electrophilic fatty acids including the arachidonic acid metabolite, 15-oxoeicosatetraenoic acid (15-oxoETE). Herein, the role of 15-oxoETE in regulating signaling responses is reported. In cell cultures, 15-oxoETE activates Nrf2-regulated antioxidant responses (AR) and inhibits NF-κB-mediated pro-inflammatory responses via IKKβ inhibition. Inhibition of glutathione S-transferases using ethacrynic acid incrementally increased the signaling capacity of 15-oxoETE by decreasing 15-oxoETE-GSH adduct formation. This work demonstrates that 15PGDH plays a role in the regulation of cell and tissue homeostasis via the production of electrophilic fatty acid signaling mediators. PMID:25450232

  10. Chlorogenic Acid Improves Late Diabetes through Adiponectin Receptor Signaling Pathways in db/db Mice

    PubMed Central

    Jin, Shasha; Chang, Cuiqing; Zhang, Lantao; Liu, Yang; Huang, Xianren; Chen, Zhimin

    2015-01-01

    The aim of this study was to examine the effects of chlorogenic acid (CGA) on glucose and lipid metabolism in late diabetic db/db mice, as well as on adiponectin receptors and their signaling molecules, to provide evidence for CGA in the prevention of type 2 diabetes. We randomly divided 16 female db/db mice into db/db-CGA and db/db-control (CON) groups equally; db/m mice were used as control mice. The mice in both the db/db-CGA and db/m-CGA groups were administered 80 mg/kg/d CGA by lavage for 12 weeks, whereas the mice in both CON groups were given equal volumes of phosphate-buffered saline (PBS) by lavage. At the end of the intervention, we assessed body fat and the parameters of glucose and lipid metabolism in the plasma, liver and skeletal muscle tissues as well as the levels of aldose reductase (AR) and transforming growth factor-β1 (TGF-β1) in the kidneys and measured adiponectin receptors and the protein expression of their signaling molecules in liver and muscle tissues. After 12 weeks of intervention, compared with the db/db-CON group, the percentage of body fat, fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c) in the db/db-CGA group were all significantly decreased; TGF-β1 protein expression and AR activity in the kidney were both decreased; and the adiponectin level in visceral adipose was increased. The protein expression of adiponectin receptors (ADPNRs), the phosphorylation of AMP-activated protein kinase (AMPK) in the liver and muscle, and the mRNA and protein levels of peroxisome proliferator-activated receptor alpha (PPAR-α) in the liver were all significantly greater. CGA could lower the levels of fasting plasma glucose and HbA1c during late diabetes and improve kidney fibrosis to some extent through the modulation of adiponectin receptor signaling pathways in db/db mice. PMID:25849026

  11. Jasmonic acid is involved in the signaling pathway for fungal endophyte-induced volatile oil accumulation of Atractylodes lancea plantlets

    PubMed Central

    2012-01-01

    Background Jasmonic acid (JA) is a well-characterized signaling molecule in plant defense responses. However, its relationships with other signal molecules in secondary metabolite production induced by endophytic fungus are largely unknown. Atractylodes lancea (Asteraceae) is a traditional Chinese medicinal plant that produces antimicrobial volatiles oils. We incubated plantlets of A. lancea with the fungus Gilmaniella sp. AL12. to research how JA interacted with other signal molecules in volatile oil production. Results Fungal inoculation increased JA generation and volatile oil accumulation. To investigate whether JA is required for volatile oil production, plantlets were treated with JA inhibitors ibuprofen (IBU) and nordihydroguaiaretic acid. The inhibitors suppressed both JA and volatile oil production, but fungal inoculation could still induce volatile oils. Plantlets were further treated with the nitric oxide (NO)-specific scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide potassium salt (cPTIO), the H2O2 inhibitors diphenylene iodonium (DPI) and catalase (CAT), and the salicylic acid (SA) biosynthesis inhibitors paclobutrazol and 2-aminoindan-2-phosphonic acid. With fungal inoculation, IBU did not inhibit NO production, and JA generation was significantly suppressed by cPTIO, showing that JA may act as a downstream signal of the NO pathway. Exogenous H2O2 could reverse the inhibitory effects of cPTIO on JA generation, indicating that NO mediates JA induction by the fungus through H2O2-dependent pathways. With fungal inoculation, the H2O2 scavenger DPI/CAT could inhibit JA generation, but IBU could not inhibit H2O2 production, implying that H2O2 directly mediated JA generation. Finally, JA generation was enhanced when SA production was suppressed, and vice versa. Conclusions Jasmonic acid acts as a downstream signaling molecule in NO- and H2O2-mediated volatile oil accumulation induced by endophytic fungus and has a complementary

  12. Ulvan, a Sulfated Polysaccharide from Green Algae, Activates Plant Immunity through the Jasmonic Acid Signaling Pathway

    PubMed Central

    Jaulneau, Valérie; Lafitte, Claude; Jacquet, Christophe; Fournier, Sylvie; Salamagne, Sylvie; Briand, Xavier; Esquerré-Tugayé, Marie-Thérèse; Dumas, Bernard

    2010-01-01

    The industrial use of elicitors as alternative tools for disease control needs the identification of abundant sources of them. We report on an elicitor obtained from the green algae Ulva spp. A fraction containing most exclusively the sulfated polysaccharide known as ulvan-induced expression of a GUS gene placed under the control of a lipoxygenase gene promoter. Gene expression profiling was performed upon ulvan treatments on Medicago truncatula and compared to phytohormone effects. Ulvan induced a gene expression signature similar to that observed upon methyl jasmonate treatment (MeJA). Involvement of jasmonic acid (JA) in ulvan response was confirmed by detecting induction of protease inhibitory activity and by hormonal profiling of JA, salicylic acid (SA) and abscisic acid (ABA). Ulvan activity on the hormonal pathway was further consolidated by using Arabidopsis hormonal mutants. Altogether, our results demonstrate that green algae are a potential reservoir of ulvan elicitor which acts through the JA pathway. PMID:20445752

  13. Uric acid induces oxidative stress and growth inhibition by activating adenosine monophosphate-activated protein kinase and extracellular signal-regulated kinase signal pathways in pancreatic β cells.

    PubMed

    Zhang, Yongneng; Yamamoto, Tetsuya; Hisatome, Ichiro; Li, Youfeng; Cheng, Weijie; Sun, Ning; Cai, Bozhi; Huang, Tianliang; Zhu, Yuzhang; Li, Zhi; Jing, Xubin; Zhou, Rui; Cheng, Jidong

    2013-08-15

    Hyperuricaemia is a disorder of purine metabolism, and is strongly associated with insulin resistance and abnormal glucose metabolism. As the producer of insulin, pancreatic β cells might be affected by elevated serum uric acid levels and contribute to the disregulated glucose metabolism. In this study, we investigated the effect of high uric acid on rat pancreatic β cell function. Under high uric acid condition, proliferation of pancreatic β cells was inhibited, production of reactive oxygen species increased, and glucose stimulated insulin secretion was also compromised. Further examination on signal transduction pathways revealed that uric acid-induced ROS is involved in the activation of adenosine monophosphate-activated protein kinase (AMPK), and extracellular signal-regulated kinase (ERK). Pharmacological inhibition of ERK activation rescued β cells from growth inhibition. More importantly, activation of ERK induced by uric acid is significantly diminished by AMPK inhibitor, indicating ERK as a downstream target of AMPK in response to high uric acid condition. We also investigated the transportation channel for uric acid into pancreatic β cells. While major urate transporter URAT1 is not expressed in β cells, organic anion transporter (OAT) inhibitor successfully blocked the activation of ERK by uric acid. Our data indicate that high uric acid levels induce oxidative damage and inhibit growth of rat pancreatic β cells by activating the AMPK and ERK signal pathways. Hyperuricemia may contribute to abnormal glucose metabolism by causing oxidative damage and function inhibition of pancreatic β cells.

  14. The Epoxyeicosatrienoic Acid Pathway Enhances Hepatic Insulin Signaling and is Repressed in Insulin-Resistant Mouse Liver.

    PubMed

    Schäfer, Alexander; Neschen, Susanne; Kahle, Melanie; Sarioglu, Hakan; Gaisbauer, Tobias; Imhof, Axel; Adamski, Jerzy; Hauck, Stefanie M; Ueffing, Marius

    2015-10-01

    Although it is widely accepted that ectopic lipid accumulation in the liver is associated with hepatic insulin resistance, the underlying molecular mechanisms have not been well characterized.Here we employed time resolved quantitative proteomic profiling of mice fed a high fat diet to determine which pathways were affected during the transition of the liver to an insulin-resistant state. We identified several metabolic pathways underlying altered protein expression. In order to test the functional impact of a critical subset of these alterations, we focused on the epoxyeicosatrienoic acid (EET) eicosanoid pathway, whose deregulation coincided with the onset of hepatic insulin resistance. These results suggested that EETs may be positive modulators of hepatic insulin signaling. Analyzing EET activity in primary hepatocytes, we found that EETs enhance insulin signaling on the level of Akt. In contrast, EETs did not influence insulin receptor or insulin receptor substrate-1 phosphorylation. This effect was mediated through the eicosanoids, as overexpression of the deregulated enzymes in absence of arachidonic acid had no impact on insulin signaling. The stimulation of insulin signaling by EETs and depression of the pathway in insulin resistant liver suggest a likely role in hepatic insulin resistance. Our findings support therapeutic potential for inhibiting EET degradation.

  15. Salicylic acid induces vanillin synthesis through the phospholipid signaling pathway in Capsicum chinense cell cultures

    PubMed Central

    Rodas-Junco, Beatriz A; Cab-Guillen, Yahaira; Muñoz-Sanchez, J Armando; Vázquez-Flota, Felipe; Monforte-Gonzalez, Miriam; Hérnandez-Sotomayor, S M Teresa

    2013-01-01

    Signal transduction via phospholipids is mediated by phospholipases such as phospholipase C (PLC) and D (PLD), which catalyze hydrolysis of plasma membrane structural phospholipids. Phospholipid signaling is also involved in plant responses to phytohormones such as salicylic acid (SA). The relationships between phospholipid signaling, SA, and secondary metabolism are not fully understood. Using a Capsicum chinense cell suspension as a model, we evaluated whether phospholipid signaling modulates SA-induced vanillin production through the activation of phenylalanine ammonia lyase (PAL), a key enzyme in the biosynthetic pathway. Salicylic acid was found to elicit PAL activity and consequently vanillin production, which was diminished or reversed upon exposure to the phosphoinositide-phospholipase C (PI-PLC) signaling inhibitors neomycin and U73122. Exposure to the phosphatidic acid inhibitor 1-butanol altered PLD activity and prevented SA-induced vanillin production. Our results suggest that PLC and PLD-generated secondary messengers may be modulating SA-induced vanillin production through the activation of key biosynthetic pathway enzymes.

  16. Gallic acid inhibits vascular calcification through the blockade of BMP2-Smad1/5/8 signaling pathway.

    PubMed

    Kee, Hae Jin; Cho, Soo-Na; Kim, Gwi Ran; Choi, Sin Young; Ryu, Yuhee; Kim, In Kyeom; Hong, Young Joon; Park, Hyung Wook; Ahn, Youngkeun; Cho, Jeong Gwan; Park, Jong Chun; Jeong, Myung Ho

    2014-11-01

    Vascular calcification is associated with increased risk of morbidity and mortality in patients with cardiovascular diseases, chronic kidney diseases, and diabetes. Gallic acid, a natural compound found in gallnut and green tea, is known to be antifungal, antioxidant, and anticancer. Here we investigated the effect of gallic acid on vascular smooth muscle cell (VSMC) calcification and the underlying mechanism. Gallic acid inhibited inorganic phosphate-induced osteoblast differentiation markers as well as calcification phenotypes (as determined by calcium deposition, Alizarin Red, and Von Kossa staining). Knockdown of BMP2 or Noggin blocked phosphate-induced calcification. Gallic acid suppressed phosphorylation of Smad1/5/8 protein induced by inorganic phosphate. Taken together, we suggest that gallic acid acts as a novel therapeutic agent of vascular calcification by mediating BMP2-Smad1/5/8 signaling pathway.

  17. Folic Acid Is Able to Polarize the Inflammatory Response in LPS Activated Microglia by Regulating Multiple Signaling Pathways

    PubMed Central

    Salvatore, Rosaria; Porro, Chiara; Trotta, Teresa

    2016-01-01

    We investigated the ability of folic acid to modulate the inflammatory responses of LPS activated BV-2 microglia cells and the signal transduction pathways involved. To this aim, the BV-2 cell line was exposed to LPS as a proinflammatory response inducer, in presence or absence of various concentrations of folic acid. The production of nitric oxide (NO) was determined by the Griess test. The levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and IL-10 were determined by ELISA. Inducible NO synthase (iNOS), nuclear transcription factor-kappa B (NF-κB) p65, MAPKs protein, and suppressors of cytokine signaling (SOCS)1 and SOCS3 were analyzed by western blotting. TNF-α and IL-1β, as well as iNOS dependent NO production, resulted significantly inhibited by folic acid pretreatment in LPS-activated BV-2 cells. We also observed that folic acid dose-dependently upregulated both SOCS1 and SOCS3 expression in BV-2 cells, leading to an increased expression of the anti-inflammatory cytokine IL-10. Finally, p-IκBα, which indirectly reflects NF-κB complex activation, and JNK phosphorylation resulted dose-dependently downregulated by folic acid pretreatment of LPS-activated cells, whereas p38 MAPK phosphorylation resulted significantly upregulated by folic acid treatment. Overall, these results demonstrated that folic acid was able to modulate the inflammatory response in microglia cells, shifting proinflammatory versus anti-inflammatory responses through regulating multiple signaling pathways. PMID:27738387

  18. Abscisic acid and blue light signaling pathways in chloroplast movements in Arabidopsis mesophyll.

    PubMed

    Eckstein, Aleksandra; Krzeszowiec, Weronika; Banaś, Agnieszka Katarzyna; Janowiak, Franciszek; Gabryś, Halina

    2016-01-01

    Abscisic acid (ABA) and phototropins act antagonistically to control stomatal movements. Here, we investigated the role of ABA in phototropin-directed chloroplast movements in mesophyll cells of Arabidopsis thaliana. We analyzed the expression of phototropins at mRNA and protein level under the influence of ABA. PHOT1 mRNA level was decreased by ABA in the dark while it was insensitive to ABA in light. PHOT2 mRNA level was independent of the hormone treatment. The levels of phototropin proteins were down-regulated by ABA, both in darkness and light. No impact of exogenous ABA on amplitudes and kinetics of chloroplast movements was detected. Chloroplast responses in wild type Arabidopsis and three mutants, abi4, abi2 (abscisic acid insensitive4, 2) and aba1 (abscisic acid1), were measured to account for endogenous ABA signaling. The chloroplast responses were slightly reduced in abi2 and aba1 mutants in strong light. To further investigate the effect, abi2 and aba1 mutants were supplemented with exogenous ABA. In the aba1 mutant, the reaction was rescued but in abi2 it was unaffected. Our results show that ABA is not directly involved in phototropin-controlled chloroplast responses in mature leaves of Arabidopsis. However, the disturbance of ABA biosynthesis and signaling in mutants affects some elements of the chloroplast movement mechanism. In line with its role as a stress hormone, ABA appears to enhance plant sensitivity to light and promote the chloroplast avoidance response.

  19. Abscisic acid and blue light signaling pathways in chloroplast movements in Arabidopsis mesophyll.

    PubMed

    Eckstein, Aleksandra; Krzeszowiec, Weronika; Banaś, Agnieszka Katarzyna; Janowiak, Franciszek; Gabryś, Halina

    2016-01-01

    Abscisic acid (ABA) and phototropins act antagonistically to control stomatal movements. Here, we investigated the role of ABA in phototropin-directed chloroplast movements in mesophyll cells of Arabidopsis thaliana. We analyzed the expression of phototropins at mRNA and protein level under the influence of ABA. PHOT1 mRNA level was decreased by ABA in the dark while it was insensitive to ABA in light. PHOT2 mRNA level was independent of the hormone treatment. The levels of phototropin proteins were down-regulated by ABA, both in darkness and light. No impact of exogenous ABA on amplitudes and kinetics of chloroplast movements was detected. Chloroplast responses in wild type Arabidopsis and three mutants, abi4, abi2 (abscisic acid insensitive4, 2) and aba1 (abscisic acid1), were measured to account for endogenous ABA signaling. The chloroplast responses were slightly reduced in abi2 and aba1 mutants in strong light. To further investigate the effect, abi2 and aba1 mutants were supplemented with exogenous ABA. In the aba1 mutant, the reaction was rescued but in abi2 it was unaffected. Our results show that ABA is not directly involved in phototropin-controlled chloroplast responses in mature leaves of Arabidopsis. However, the disturbance of ABA biosynthesis and signaling in mutants affects some elements of the chloroplast movement mechanism. In line with its role as a stress hormone, ABA appears to enhance plant sensitivity to light and promote the chloroplast avoidance response. PMID:27486921

  20. The Osmoregulatory and the Amino Acid-regulated Responses of System A Are Mediated by Different Signal Transduction Pathways

    PubMed Central

    López-Fontanals, Marta; Rodríguez-Mulero, Silvia; Casado, F. Javier; Dérijard, Benoit; Pastor-Anglada, Marçal

    2003-01-01

    The osmotic response of system A for neutral amino acid transport has been related to the adaptive response of this transport system to amino acid starvation. In a previous study (Ruiz-Montasell, B., M. Gómez-Angelats, F.J. Casado, A. Felipe, J.D. McGivan, and M. Pastor-Anglada. 1994. Proc. Natl. Acad. Sci. USA. 91:9569–9573), a model was proposed in which both responses were mediated by different mechanisms. The recent cloning of several isoforms of system A as well as the elucidation of a variety of signal transduction pathways involved in stress responses allow to test this model. SAT2 mRNA levels increased after amino acid deprivation but not after hyperosmotic shock. Inhibition of p38 activity or transfection with a dominant negative p38 did not alter the response to amino acid starvation but partially blocked the hypertonicity response. Inhibition of the ERK pathway resulted in full inhibition of the adaptive response of system A and no increase in SAT2 mRNA levels, without modifying the response to hyperosmolarity. Similar results were obtained after transfection with a dominant negative JNK1. The CDK2 inhibitor peptide-II decreased the osmotic response in a dose-dependent manner but did not have any effect on the adaptive response of system A. In summary, the previously proposed model of up-regulation of system A after hypertonic shock or after amino acid starvation by separate mechanisms is now confirmed and the two signal transduction pathways have been identified. The involvement of a CDK–cyclin complex in the osmotic response of system A links the activity of this transporter to the increase in cell volume previous to the entry in a new cell division cycle. PMID:12810851

  1. Chemosensory signalling pathways involved in sensing of amino acids by the ghrelin cell

    PubMed Central

    Vancleef, L.; Van Den Broeck, T.; Thijs, T.; Steensels, S.; Briand, L.; Tack, J.; Depoortere, I.

    2015-01-01

    Taste receptors on enteroendocrine cells sense nutrients and transmit signals that control gut hormone release. This study aimed to investigate the amino acid (AA) sensing mechanisms of the ghrelin cell in a gastric ghrelinoma cell line, tissue segments and mice. Peptone and specific classes of amino acids stimulate ghrelin secretion in the ghrelinoma cell line. Sensing of L-Phe occurs via the CaSR, monosodium glutamate via the TAS1R1-TAS1R3 while L-Ala and peptone act via 2 different amino acid taste receptors: CaSR & TAS1R1-TAS1R3 and CaSR & GPRC6A, respectively. The stimulatory effect of peptone on ghrelin release was mimicked ex vivo in gastric but not in jejunal tissue segments, where peptone inhibited ghrelin release. The latter effect could not be blocked by receptor antagonists for CCK, GLP-1 or somatostatin. In vivo, plasma ghrelin levels were reduced both upon intragastric (peptone or L-Phe) or intravenous (L-Phe) administration, indicating that AA- sensing is not polarized and is due to inhibition of ghrelin release from the stomach or duodenum respectively. In conclusion, functional AA taste receptors regulate AA-induced ghrelin release in vitro. The effects differ between stomach and jejunum but these local nutrient sensing mechanisms are overruled in vivo by indirect mechanisms inhibiting ghrelin release. PMID:26510380

  2. Chemosensory signalling pathways involved in sensing of amino acids by the ghrelin cell.

    PubMed

    Vancleef, L; Van Den Broeck, T; Thijs, T; Steensels, S; Briand, L; Tack, J; Depoortere, I

    2015-01-01

    Taste receptors on enteroendocrine cells sense nutrients and transmit signals that control gut hormone release. This study aimed to investigate the amino acid (AA) sensing mechanisms of the ghrelin cell in a gastric ghrelinoma cell line, tissue segments and mice. Peptone and specific classes of amino acids stimulate ghrelin secretion in the ghrelinoma cell line. Sensing of L-Phe occurs via the CaSR, monosodium glutamate via the TAS1R1-TAS1R3 while L-Ala and peptone act via 2 different amino acid taste receptors: CaSR &TAS1R1-TAS1R3 and CaSR &GPRC6A, respectively. The stimulatory effect of peptone on ghrelin release was mimicked ex vivo in gastric but not in jejunal tissue segments, where peptone inhibited ghrelin release. The latter effect could not be blocked by receptor antagonists for CCK, GLP-1 or somatostatin. In vivo, plasma ghrelin levels were reduced both upon intragastric (peptone or L-Phe) or intravenous (L-Phe) administration, indicating that AA- sensing is not polarized and is due to inhibition of ghrelin release from the stomach or duodenum respectively. In conclusion, functional AA taste receptors regulate AA-induced ghrelin release in vitro. The effects differ between stomach and jejunum but these local nutrient sensing mechanisms are overruled in vivo by indirect mechanisms inhibiting ghrelin release. PMID:26510380

  3. A hepatic amino acid/mTOR/S6K-dependent signalling pathway modulates systemic lipid metabolism via neuronal signals

    PubMed Central

    Uno, Kenji; Yamada, Tetsuya; Ishigaki, Yasushi; Imai, Junta; Hasegawa, Yutaka; Sawada, Shojiro; Kaneko, Keizo; Ono, Hiraku; Asano, Tomoichiro; Oka, Yoshitomo; Katagiri, Hideki

    2015-01-01

    Metabolism is coordinated among tissues and organs via neuronal signals. Levels of circulating amino acids (AAs), which are elevated in obesity, activate the intracellular target of rapamycin complex-1 (mTORC1)/S6kinase (S6K) pathway in the liver. Here we demonstrate that hepatic AA/mTORC1/S6K signalling modulates systemic lipid metabolism via a mechanism involving neuronal inter-tissue communication. Hepatic expression of an AA transporter, SNAT2, activates the mTORC1/S6K pathway, and markedly elevates serum triglycerides (TGs), while downregulating adipose lipoprotein lipase (LPL). Hepatic Rheb or active-S6K expression have similar metabolic effects, whereas hepatic expression of dominant-negative-S6K inhibits TG elevation in SNAT2 mice. Denervation, pharmacological deafferentation and β-blocker administration suppress obesity-related hypertriglyceridemia with adipose LPL upregulation, suggesting that signals are transduced between liver and adipose tissue via a neuronal pathway consisting of afferent vagal and efferent sympathetic nerves. Thus, the neuronal mechanism uncovered here serves to coordinate amino acid and lipid levels and contributes to the development of obesity-related hypertriglyceridemia. PMID:26268630

  4. A WRKY gene from creosote bush encodes an activator of the abscisic acid signaling pathway.

    PubMed

    Zou, Xiaolu; Seemann, Jeffrey R; Neuman, Dawn; Shen, Qingxi J

    2004-12-31

    The creosote bush (Larrea tridentata) is a xerophytic evergreen C3 shrub thriving in vast arid areas of North America. As the first step toward understanding the molecular mechanisms controlling the drought tolerance of this desert plant, we have isolated a dozen genes encoding transcription factors, including LtWRKY21 that encodes a protein of 314 amino acid residues. Transient expression studies with the GFP-LtWRKY21 fusion construct indicate that the LtWRKY21 protein is localized in the nucleus and is able to activate the promoter of an abscisic acid (ABA)-inducible gene, HVA22, in a dosage-dependent manner. The transactivating activity of LtWRKY21 relies on the C-terminal sequence containing the WRKY domain and a N-terminal motif that is essential for the repression activity of some regulators in ethylene signaling. LtWRKY21 interacts synergistically with ABA and transcriptional activators VP1 and ABI5 to control the expression of the HVA22 promoter. Co-expression of VP1, ABI5, and LtWRKY21 leads to a much higher expression of the HVA22 promoter than does the ABA treatment alone. In contrast, the Lt-WRKY21-mediated transactivation is inhibited by two known negative regulators of ABA signaling: 1-butanol, an inhibitor of phospholipase D, and abi1-1, a dominant negative mutant protein phosphatase. Interestingly, abi1-1 does not block the synergistic effect of LtWRKY21, VP1, and ABI5 co-expression, indicating that LtWRKY21, VP1, and ABI5 may form a complex that functions downstream of ABI1 to control ABA-regulated expression of genes.

  5. Gaseous 3-pentanol primes plant immunity against a bacterial speck pathogen, Pseudomonas syringae pv. tomato via salicylic acid and jasmonic acid-dependent signaling pathways in Arabidopsis

    PubMed Central

    Song, Geun C.; Choi, Hye K.; Ryu, Choong-Min

    2015-01-01

    3-Pentanol is an active organic compound produced by plants and is a component of emitted insect sex pheromones. A previous study reported that drench application of 3-pentanol elicited plant immunity against microbial pathogens and an insect pest in crop plants. Here, we evaluated whether 3-pentanol and the derivatives 1-pentanol and 2-pentanol induced plant systemic resistance using the in vitro I-plate system. Exposure of Arabidopsis seedlings to 10 μM and 100 nM 3-pentanol evaporate elicited an immune response to Pseudomonas syringae pv. tomato DC3000. We performed quantitative real-time PCR to investigate the 3-pentanol-mediated Arabidopsis immune responses by determining Pathogenesis-Related (PR) gene expression levels associated with defense signaling through salicylic acid (SA), jasmonic acid (JA), and ethylene signaling pathways. The results show that exposure to 3-pentanol and subsequent pathogen challenge upregulated PDF1.2 and PR1 expression. Selected Arabidopsis mutants confirmed that the 3-pentanol-mediated immune response involved SA and JA signaling pathways and the NPR1 gene. Taken together, this study indicates that gaseous 3-pentanol triggers induced resistance in Arabidopsis by priming SA and JA signaling pathways. To our knowledge, this is the first report that a volatile compound of an insect sex pheromone triggers plant systemic resistance against a bacterial pathogen. PMID:26500665

  6. The effects of centrally injected arachidonic acid on respiratory system: Involvement of cyclooxygenase to thromboxane signaling pathway.

    PubMed

    Erkan, Leman Gizem; Guvenc, Gokcen; Altinbas, Burcin; Niaz, Nasir; Yalcin, Murat

    2016-05-01

    Arachidonic acid (AA) is a polyunsaturated fatty acid that is present in the phospholipids of the cell membranes of the body and is abundant in the brain. Exogenously administered AA has been shown to affect brain metabolism and to exhibit cardiovascular and neuroendocrine actions. However, little is known regarding its respiratory actions and/or central mechanism of its respiratory effects. Therefore, the present study was designed to investigate the possible effects of centrally injected AA on respiratory system and the mediation of the central cyclooxygenase (COX) to thromboxane A2 (TXA2) signaling pathway on AA-induced respiratory effects in anaesthetized rats. Intracerebroventricular (i.c.v.) administration of AA induced dose- and time-dependent increase in tidal volume, respiratory rates and respiratory minute ventilation and also caused an increase in partial oxygen pressure (pO2) and decrease in partial carbon dioxide pressure (pCO2) in male anaesthetized Spraque Dawley rats. I.c.v. pretreatment with ibuprofen, a non-selective COX inhibitor, completely blocked the hyperventilation and blood gases changes induced by AA. In addition, central pretreatment with different doses of furegrelate, a TXA2 synthesis inhibitor, also partially prevented AA-evoked hyperventilation and blood gases effects. These data explicitly show that centrally administered AA induces hyperventilation with increasing pO2 and decreasing pCO2 levels which are mediated by the activation of central COX to TXA2 signaling pathway.

  7. Abscisic acid signals reorientation of polyamine metabolism to orchestrate stress responses via the polyamine exodus pathway in grapevine.

    PubMed

    Toumi, Imene; Moschou, Panagiotis N; Paschalidis, Konstantinos A; Bouamama, Badra; Ben Salem-Fnayou, Asma; Ghorbel, Abdel Wahed; Mliki, Ahmed; Roubelakis-Angelakis, Kalliopi A

    2010-05-01

    Polyamines (PAs) have been suggested to be implicated in plant responses to abiotic and biotic stress. Grapevine is a model perennial plant species whose cultivars respond differently to osmotic stress. In this study, we used two cultivars, one sensitive (S) and one tolerant (T) to drought. In adult vines subjected to drought under greenhouse conditions, total PAs were significantly lower in the control T- and higher in the control S-genotype and significantly increased or decreased, respectively, post-treatment. Soluble Put and Spd exhibited the greatest increase on d 8 post-treatment in the T- but not in the S-genotype, which accumulated soluble Spm. Abscisic acid (ABA) was differentially accumulated in T- and S-genotypes under drought conditions, and activated the PA biosynthetic pathway, which in turn was correlated with the differential increases in PA titers. In parallel, polyamine oxidases (PAOs) increased primarily in the S-genotype. ABA at least partially induced PA accumulation and exodus into the apoplast, where they were oxidized by the apoplastic amine oxidases (AOs), producing H2O2, which signaled secondary stress responses. The results here show that the ABA signaling pathway integrates PAs and AOs to regulate the generation of H2O2, which signals further stress responses or the PCD syndrome.

  8. Ursolic Acid Increases Glucose Uptake through the PI3K Signaling Pathway in Adipocytes

    PubMed Central

    He, Yonghan; Li, Wen; Li, Ying; Zhang, Shuocheng; Wang, Yanwen; Sun, Changhao

    2014-01-01

    Background Ursolic acid (UA), a triterpenoid compound, is reported to have a glucose-lowering effect. However, the mechanisms are not fully understood. Adipose tissue is one of peripheral tissues that collectively control the circulating glucose levels. Objective The objective of the present study was to determine the effect and further the mechanism of action of UA in adipocytes. Methods and Results The 3T3-L1 preadipocytes were induced to differentiate and treated with different concentrations of UA. NBD-fluorescent glucose was used as the tracer to measure glucose uptake and Western blotting used to determine the expression and activity of proteins involved in glucose transport. It was found that 2.5, 5 and 10 µM of UA promoted glucose uptake in a dose-dependent manner (17%, 29% and 35%, respectively). 10 µM UA-induced glucose uptake with insulin stimulation was completely blocked by the phosphatidylinositol (PI) 3-kinase (PI3K) inhibitor wortmannin (1 µM), but not by SB203580 (10 µM), the inhibitor of mitogen-activated protein kinase (MAPK), or compound C (2.5 µM), the inhibitor of AMP-activated kinase (AMPK) inhibitor. Furthmore, the downstream protein activities of the PI3K pathway, phosphoinositide-dependent kinase (PDK) and phosphoinositide-dependent serine/threoninekinase (AKT) were increased by 10 µM of UA in the presence of insulin. Interestingly, the activity of AS160 and protein kinase C (PKC) and the expression of glucose transporter 4 (GLUT4) were stimulated by 10 µM of UA under either the basal or insulin-stimulated status. Moreover, the translocation of GLUT4 from cytoplasm to cell membrane was increased by UA but decreased when the PI3K inhibitor was applied. Conclusions Our results suggest that UA stimulates glucose uptake in 3T3-L1 adipocytes through the PI3K pathway, providing important information regarding the mechanism of action of UA for its anti-diabetic effect. PMID:25329874

  9. Fatty Acid-binding Protein 4, a Point of Convergence for Angiogenic and Metabolic Signaling Pathways in Endothelial Cells*

    PubMed Central

    Harjes, Ulrike; Bridges, Esther; McIntyre, Alan; Fielding, Barbara A.; Harris, Adrian L.

    2014-01-01

    Fatty acid-binding protein 4 (FABP4) is an adipogenic protein and is implicated in atherosclerosis, insulin resistance, and cancer. In endothelial cells, FABP4 is induced by VEGFA, and inhibition of FABP4 blocks most of the VEGFA effects. We investigated the DLL4-NOTCH-dependent regulation of FABP4 in human umbilical vein endothelial cells by gene/protein expression and interaction analyses following inhibitor treatment and RNA interference. We found that FABP4 is directly induced by NOTCH. Stimulation of NOTCH signaling with human recombinant DLL4 led to FABP4 induction, independently of VEGFA. FABP4 induction by VEGFA was reduced by blockade of DLL4 binding to NOTCH or inhibition of NOTCH signal transduction. Chromatin immunoprecipitation of the NOTCH intracellular domain showed increased binding to two specific regions in the FABP4 promoter. The induction of FABP4 gene expression was dependent on the transcription factor FOXO1, which was essential for basal expression of FABP4, and FABP4 up-regulation following stimulation of the VEGFA and/or the NOTCH pathway. Thus, we show that the DLL4-NOTCH pathway mediates endothelial FABP4 expression. This indicates that induction of the angiogenesis-restricting DLL4-NOTCH can have pro-angiogenic effects via this pathway. It also provides a link between DLL4-NOTCH and FOXO1-mediated regulation of endothelial gene transcription, and it shows that DLL4-NOTCH is a nodal point in the integration of pro-angiogenic and metabolic signaling in endothelial cells. This may be crucial for angiogenesis in the tumor environment. PMID:24939870

  10. Crosstalk between cystine and glutathione is critical for the regulation of amino acid signaling pathways and ferroptosis

    PubMed Central

    Yu, Xinlei; Long, Yun Chau

    2016-01-01

    Although essential amino acids regulate mechanistic target of rapamycin complex 1 (mTORC1) and the integrated stress response (ISR), the role of cysteine is unknown. We found that in hepatoma HepG2 cells, cystine (oxidized form of cysteine) activated mTORC1 and suppressed the ISR. Cystine deprivation induced GSH efflux and extracellular degradation, which aimed to restore cellular cysteine. Inhibition of γ-glutamyl transpeptidase (GGT) impaired the ability of GSH or cell-permeable GSH to restore mTORC1 signaling and the ISR, suggesting that the capacity of GSH to release cysteine, but not GSH per se, regulated the signaling networks. Inhibition of protein translation restored both mTORC1 signaling and the ISR during cystine starvation, suggesting the bulk of cellular cysteine was committed to the biosynthetic process. Cellular cysteine and GSH displayed overlapping protective roles in the suppression of ferroptosis, further supporting their cooperation in the regulation of cell signaling. Thus, cellular cysteine and its derivative GSH cooperate to regulate mTORC1 pathway, the ISR and ferroptosis. PMID:27425006

  11. Crosstalk between cystine and glutathione is critical for the regulation of amino acid signaling pathways and ferroptosis.

    PubMed

    Yu, Xinlei; Long, Yun Chau

    2016-01-01

    Although essential amino acids regulate mechanistic target of rapamycin complex 1 (mTORC1) and the integrated stress response (ISR), the role of cysteine is unknown. We found that in hepatoma HepG2 cells, cystine (oxidized form of cysteine) activated mTORC1 and suppressed the ISR. Cystine deprivation induced GSH efflux and extracellular degradation, which aimed to restore cellular cysteine. Inhibition of γ-glutamyl transpeptidase (GGT) impaired the ability of GSH or cell-permeable GSH to restore mTORC1 signaling and the ISR, suggesting that the capacity of GSH to release cysteine, but not GSH per se, regulated the signaling networks. Inhibition of protein translation restored both mTORC1 signaling and the ISR during cystine starvation, suggesting the bulk of cellular cysteine was committed to the biosynthetic process. Cellular cysteine and GSH displayed overlapping protective roles in the suppression of ferroptosis, further supporting their cooperation in the regulation of cell signaling. Thus, cellular cysteine and its derivative GSH cooperate to regulate mTORC1 pathway, the ISR and ferroptosis. PMID:27425006

  12. Taurolithocholic acid promotes intrahepatic cholangiocarcinoma cell growth via muscarinic acetylcholine receptor and EGFR/ERK1/2 signaling pathway.

    PubMed

    Amonyingcharoen, Sumet; Suriyo, Tawit; Thiantanawat, Apinya; Watcharasit, Piyajit; Satayavivad, Jutamaad

    2015-01-01

    Cholangiocarcinoma (CCA) is a malignant cancer of the biliary tract and its occurrence is associated with chronic cholestasis which causes an elevation of bile acids in the liver and bile duct. The present study aimed to investigate the role and mechanistic effect of bile acids on the CCA cell growth. Intrahepatic CCA cell lines, RMCCA-1 and HuCCA-1, were treated with bile acids and their metabolites to determine the growth promoting effect. Cell viability, cell cycle analysis, EdU incorporation assays were conducted. Intracellular signaling proteins were detected by western immunoblotting. Among eleven forms of bile acids and their metabolites, only taurolithocholic acid (TLCA) concentration dependently (1-40 µM) increased the cell viability of RMCCA-1, but not HuCCA-1 cells. The cell cycle analysis showed induction of cells in the S phase and the EdU incorporation assay revealed induction of DNA synthesis in the TLCA-treated RMCCA-1 cells. Moreover, TLCA increased the phosphorylation of EGFR, ERK 1/2 and also increased the expression of cyclin D1 in RMCCA-1 cells. Furthermore, TLCA-induced RMCCA-1 cell growth could be inhibited by atropine, a non-selective muscarinic acetylcholine receptor (mAChR) antagonist, AG 1478, a specific EGFR inhibitor, or U 0126, a specific MEK 1/2 inhibitor. These results suggest that TLCA induces CCA cell growth via mAChR and EGFR/EKR1/2 signaling pathway. Moreover, the functional presence of cholinergic system plays a certain role in TLCA-induced CCA cell growth.

  13. Arsenic acid inhibits proliferation of skin fibroblasts, and increases cellular senescence through ROS mediated MST1-FOXO signaling pathway.

    PubMed

    Yamaguchi, Yuya; Madhyastha, Harishkumar; Madhyastha, Radha; Choijookhuu, Narantsog; Hishikawa, Yoshitaka; Pengjam, Yutthana; Nakajima, Yuichi; Maruyama, Masugi

    2016-02-01

    Arsenic exposure through drinking water is a major public health problem. It causes a number of toxic effects on skin. Arsenic has been reported to inhibit cell proliferation in in vitro conditions. However, reports about the molecular mechanisms are limited. Here, we investigated the mechanism involved in arsenic acid-mediated inhibition of cell proliferation using mouse skin fibroblast cell line. The present study found that 10 ppm arsenic acid inhibited cell proliferation, without any effect on cell death. Arsenic acid induced the generation of reactive oxygen species (ROS), resulting in oxidative stress to DNA. It also activated the mammalian Ste20-like protein kinase 1 (MST1); however the serine/threonine kinase Akt was downregulated. Forkhead box O (FOXO) transcription factors are activated through phosphorylation by MST1 under stress conditions. They are inhibited by phosphorylation by Akt through external and internal stimuli. Activation of FOXOs results in their nuclear localization, followed by an increase in transcriptional activity. Our results showed that arsenic induced the nuclear translocation of FOXO1 and FOXO3a, and altered the cell cycle, with cells accumulating at the G2/M phase. These effects caused cellular senescence. Taken together, our results indicate that arsenic acid inhibited cell proliferation through cellular senescence process regulated by MST1-FOXO signaling pathway. PMID:26763397

  14. The NPR1-dependent salicylic acid signalling pathway is pivotal for enhanced salt and oxidative stress tolerance in Arabidopsis.

    PubMed

    Jayakannan, Maheswari; Bose, Jayakumar; Babourina, Olga; Shabala, Sergey; Massart, Amandine; Poschenrieder, Charlotte; Rengel, Zed

    2015-04-01

    The role of endogenous salicylic acid (SA) signalling cascades in plant responses to salt and oxidative stresses is unclear. Arabidopsis SA signalling mutants, namely npr1-5 (non-expresser of pathogenesis related gene1), which lacks NPR1-dependent SA signalling, and nudt7 (nudix hydrolase7), which has both constitutively expressed NPR1-dependent and NPR1-independent SA signalling pathways, were compared with the wild type (Col-0) during salt or oxidative stresses. Growth and viability staining showed that, compared with wild type, the npr1-5 mutant was sensitive to either salt or oxidative stress, whereas the nudt7 mutant was tolerant. Acute salt stress caused the strongest membrane potential depolarization, highest sodium and proton influx, and potassium loss from npr1-5 roots in comparison with the wild type and nudt7 mutant. Though salt stress-induced hydrogen peroxide production was lowest in the npr1-5 mutant, the reactive oxygen species (ROS) stress (induced by 1mM of hydroxyl-radical-generating copper-ascorbate mix, or either 1 or 10mM hydrogen peroxide) caused a higher potassium loss from the roots of the npr1-5 mutant than the wild type and nudt7 mutant. Long-term salt exposure resulted in the highest sodium and the lowest potassium concentration in the shoots of npr1-5 mutant in comparison with the wild type and nudt7 mutant. The above results demonstrate that NPR1-dependent SA signalling is pivotal to (i) controlling Na(+) entry into the root tissue and its subsequent long-distance transport into the shoot, and (ii) preventing a potassium loss through depolarization-activated outward-rectifying potassium and ROS-activated non-selective cation channels. In conclusion, NPR1-dependent SA signalling is central to the salt and oxidative stress tolerance in Arabidopsis. PMID:25614660

  15. The NPR1-dependent salicylic acid signalling pathway is pivotal for enhanced salt and oxidative stress tolerance in Arabidopsis

    PubMed Central

    Jayakannan, Maheswari; Bose, Jayakumar; Babourina, Olga; Shabala, Sergey; Massart, Amandine; Poschenrieder, Charlotte; Rengel, Zed

    2015-01-01

    The role of endogenous salicylic acid (SA) signalling cascades in plant responses to salt and oxidative stresses is unclear. Arabidopsis SA signalling mutants, namely npr1-5 (non-expresser of pathogenesis related gene1), which lacks NPR1-dependent SA signalling, and nudt7 (nudix hydrolase7), which has both constitutively expressed NPR1-dependent and NPR1-independent SA signalling pathways, were compared with the wild type (Col-0) during salt or oxidative stresses. Growth and viability staining showed that, compared with wild type, the npr1-5 mutant was sensitive to either salt or oxidative stress, whereas the nudt7 mutant was tolerant. Acute salt stress caused the strongest membrane potential depolarization, highest sodium and proton influx, and potassium loss from npr1-5 roots in comparison with the wild type and nudt7 mutant. Though salt stress-induced hydrogen peroxide production was lowest in the npr1-5 mutant, the reactive oxygen species (ROS) stress (induced by 1mM of hydroxyl-radical-generating copper-ascorbate mix, or either 1 or 10mM hydrogen peroxide) caused a higher potassium loss from the roots of the npr1-5 mutant than the wild type and nudt7 mutant. Long-term salt exposure resulted in the highest sodium and the lowest potassium concentration in the shoots of npr1-5 mutant in comparison with the wild type and nudt7 mutant. The above results demonstrate that NPR1-dependent SA signalling is pivotal to (i) controlling Na+ entry into the root tissue and its subsequent long-distance transport into the shoot, and (ii) preventing a potassium loss through depolarization-activated outward-rectifying potassium and ROS-activated non-selective cation channels. In conclusion, NPR1-dependent SA signalling is central to the salt and oxidative stress tolerance in Arabidopsis. PMID:25614660

  16. The NPR1-dependent salicylic acid signalling pathway is pivotal for enhanced salt and oxidative stress tolerance in Arabidopsis.

    PubMed

    Jayakannan, Maheswari; Bose, Jayakumar; Babourina, Olga; Shabala, Sergey; Massart, Amandine; Poschenrieder, Charlotte; Rengel, Zed

    2015-04-01

    The role of endogenous salicylic acid (SA) signalling cascades in plant responses to salt and oxidative stresses is unclear. Arabidopsis SA signalling mutants, namely npr1-5 (non-expresser of pathogenesis related gene1), which lacks NPR1-dependent SA signalling, and nudt7 (nudix hydrolase7), which has both constitutively expressed NPR1-dependent and NPR1-independent SA signalling pathways, were compared with the wild type (Col-0) during salt or oxidative stresses. Growth and viability staining showed that, compared with wild type, the npr1-5 mutant was sensitive to either salt or oxidative stress, whereas the nudt7 mutant was tolerant. Acute salt stress caused the strongest membrane potential depolarization, highest sodium and proton influx, and potassium loss from npr1-5 roots in comparison with the wild type and nudt7 mutant. Though salt stress-induced hydrogen peroxide production was lowest in the npr1-5 mutant, the reactive oxygen species (ROS) stress (induced by 1mM of hydroxyl-radical-generating copper-ascorbate mix, or either 1 or 10mM hydrogen peroxide) caused a higher potassium loss from the roots of the npr1-5 mutant than the wild type and nudt7 mutant. Long-term salt exposure resulted in the highest sodium and the lowest potassium concentration in the shoots of npr1-5 mutant in comparison with the wild type and nudt7 mutant. The above results demonstrate that NPR1-dependent SA signalling is pivotal to (i) controlling Na(+) entry into the root tissue and its subsequent long-distance transport into the shoot, and (ii) preventing a potassium loss through depolarization-activated outward-rectifying potassium and ROS-activated non-selective cation channels. In conclusion, NPR1-dependent SA signalling is central to the salt and oxidative stress tolerance in Arabidopsis.

  17. Linoleic acid and stearic acid elicit opposite effects on AgRP expression and secretion via TLR4-dependent signaling pathways in immortalized hypothalamic N38 cells.

    PubMed

    Wang, Songbo; Xiang, Nana; Yang, Liusong; Zhu, Canjun; Zhu, Xiaotong; Wang, Lina; Gao, Ping; Xi, Qianyun; Zhang, Yongliang; Shu, Gang; Jiang, Qingyan

    2016-03-18

    The regulation of food intake is a promising way to combat obesity. It has been implicated that various fatty acids exert different effects on food intake and body weight. However, the underlying mechanism remains poorly understood. The aim of the present study was to investigate the effects of linoleic acid (LA) and stearic acid (SA) on agouti-related protein (AgRP) expression and secretion in immortalized mouse hypothalamic N38 cells and to explore the likely underlying mechanisms. Our results demonstrated that LA inhibited, while SA stimulated AgRP expression and secretion of N38 cells in a dose-dependent manner. In addition, LA suppressed the protein expression of toll-like receptor 4 (TLR4), phosphorylation levels of JNK and IKKα/β, suggesting the inhibition of TLR4-dependent inflammation pathway. However, the above mentioned inhibitory effects of LA were eliminated by TLR4 agonist lipopolysaccharide (LPS). In contrast, SA promoted TLR4 protein expression and activated TLR4-dependent inflammation pathway, with elevated ratio of p-JNK/JNK. While TLR4 siRNA reversed the stimulatory effects of SA on AgRP expression and TLR4-dependent inflammation. Moreover, we found that TLR4 was also involved in LA-enhanced and SA-impaired leptin/insulin signal pathways in N38 cells. In conclusion, our findings indicated that LA elicited inhibitory while SA exerted stimulatory effects on AgRP expression and secretion via TLR4-dependent inflammation and leptin/insulin pathways in N38 cells. These data provided a better understanding of the mechanism underlying fatty acids-regulated food intake and suggested the potential role of long-chain unsaturated fatty acids such as LA in reducing food intake and treating obesity.

  18. Alleviation of Drought Stress by Hydrogen Sulfide Is Partially Related to the Abscisic Acid Signaling Pathway in Wheat

    PubMed Central

    Wang, Chenyang; Qin, Haixia; Han, Qiaoxia; Hou, Junfeng; Lu, Hongfang; Xie, Yingxin; Guo, Tiancai

    2016-01-01

    Little information is available describing the effects of exogenous H2S on the ABA pathway in the acquisition of drought tolerance in wheat. In this study, we investigated the physiological parameters, the transcription levels of several genes involved in the abscisic acid (ABA) metabolism pathway, and the ABA and H2S contents in wheat leaves and roots under drought stress in response to exogenous NaHS treatment. The results showed that pretreatment with NaHS significantly increased plant height and the leaf relative water content of seedlings under drought stress. Compared with drought stress treatment alone, H2S application increased antioxidant enzyme activities and reduced MDA and H2O2 contents in both leaves and roots. NaHS pretreatment increased the expression levels of ABA biosynthesis and ABA reactivation genes in leaves; whereas the expression levels of ABA biosynthesis and ABA catabolism genes were up-regulated in roots. These results indicated that ABA participates in drought tolerance induced by exogenous H2S, and that the responses in leaves and roots are different. The transcription levels of genes encoding ABA receptors were up-regulated in response to NaHS pretreatment under drought conditions in both leaves and roots. Correspondingly, the H2S contents in leaves and roots were increased by NaHS pretreatment, while the ABA contents of leaves and roots decreased. This implied that there is complex crosstalk between these two signal molecules, and that the alleviation of drought stress by H2S, at least in part, involves the ABA signaling pathway. PMID:27649534

  19. Alleviation of Drought Stress by Hydrogen Sulfide Is Partially Related to the Abscisic Acid Signaling Pathway in Wheat.

    PubMed

    Ma, Dongyun; Ding, Huina; Wang, Chenyang; Qin, Haixia; Han, Qiaoxia; Hou, Junfeng; Lu, Hongfang; Xie, Yingxin; Guo, Tiancai

    2016-01-01

    Little information is available describing the effects of exogenous H2S on the ABA pathway in the acquisition of drought tolerance in wheat. In this study, we investigated the physiological parameters, the transcription levels of several genes involved in the abscisic acid (ABA) metabolism pathway, and the ABA and H2S contents in wheat leaves and roots under drought stress in response to exogenous NaHS treatment. The results showed that pretreatment with NaHS significantly increased plant height and the leaf relative water content of seedlings under drought stress. Compared with drought stress treatment alone, H2S application increased antioxidant enzyme activities and reduced MDA and H2O2 contents in both leaves and roots. NaHS pretreatment increased the expression levels of ABA biosynthesis and ABA reactivation genes in leaves; whereas the expression levels of ABA biosynthesis and ABA catabolism genes were up-regulated in roots. These results indicated that ABA participates in drought tolerance induced by exogenous H2S, and that the responses in leaves and roots are different. The transcription levels of genes encoding ABA receptors were up-regulated in response to NaHS pretreatment under drought conditions in both leaves and roots. Correspondingly, the H2S contents in leaves and roots were increased by NaHS pretreatment, while the ABA contents of leaves and roots decreased. This implied that there is complex crosstalk between these two signal molecules, and that the alleviation of drought stress by H2S, at least in part, involves the ABA signaling pathway. PMID:27649534

  20. Saturated fatty acids activate TLR-mediated pro-inflammatory signaling pathways

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Toll-like receptor 4 (TLR4) and TLR2 were shown to be activated by saturated fatty acids (SFAs) but inhibited by docosahexaenoic acid (DHA). However, one report (ATVB 11:1944, 2009) suggested that SFA-induced TLR activation in cell culture systems is due to contaminants in BSA used for conjugating f...

  1. Signaling Pathways in Melanogenesis

    PubMed Central

    D’Mello, Stacey A. N.; Finlay, Graeme J.; Baguley, Bruce C.; Askarian-Amiri, Marjan E.

    2016-01-01

    Melanocytes are melanin-producing cells found in skin, hair follicles, eyes, inner ear, bones, heart and brain of humans. They arise from pluripotent neural crest cells and differentiate in response to a complex network of interacting regulatory pathways. Melanins are pigment molecules that are endogenously synthesized by melanocytes. The light absorption of melanin in skin and hair leads to photoreceptor shielding, thermoregulation, photoprotection, camouflage and display coloring. Melanins are also powerful cation chelators and may act as free radical sinks. Melanin formation is a product of complex biochemical events that starts from amino acid tyrosine and its metabolite, dopa. The types and amounts of melanin produced by melanocytes are determined genetically and are influenced by a variety of extrinsic and intrinsic factors such as hormonal changes, inflammation, age and exposure to UV light. These stimuli affect the different pathways in melanogenesis. In this review we will discuss the regulatory mechanisms involved in melanogenesis and explain how intrinsic and extrinsic factors regulate melanin production. We will also explain the regulatory roles of different proteins involved in melanogenesis. PMID:27428965

  2. Signaling Pathways in Melanogenesis.

    PubMed

    D'Mello, Stacey A N; Finlay, Graeme J; Baguley, Bruce C; Askarian-Amiri, Marjan E

    2016-01-01

    Melanocytes are melanin-producing cells found in skin, hair follicles, eyes, inner ear, bones, heart and brain of humans. They arise from pluripotent neural crest cells and differentiate in response to a complex network of interacting regulatory pathways. Melanins are pigment molecules that are endogenously synthesized by melanocytes. The light absorption of melanin in skin and hair leads to photoreceptor shielding, thermoregulation, photoprotection, camouflage and display coloring. Melanins are also powerful cation chelators and may act as free radical sinks. Melanin formation is a product of complex biochemical events that starts from amino acid tyrosine and its metabolite, dopa. The types and amounts of melanin produced by melanocytes are determined genetically and are influenced by a variety of extrinsic and intrinsic factors such as hormonal changes, inflammation, age and exposure to UV light. These stimuli affect the different pathways in melanogenesis. In this review we will discuss the regulatory mechanisms involved in melanogenesis and explain how intrinsic and extrinsic factors regulate melanin production. We will also explain the regulatory roles of different proteins involved in melanogenesis. PMID:27428965

  3. Jasmonic acid enhancement of anthocyanin accumulation is dependent on phytochrome A signaling pathway under far-red light in Arabidopsis.

    PubMed

    Li, Ting; Jia, Kun-Peng; Lian, Hong-Li; Yang, Xu; Li, Ling; Yang, Hong-Quan

    2014-11-01

    Anthocyanins are critical for plants. It is shown that the expression of genes encoding the key enzymes such as dihydroflavonol 4-reductase (DFR), UDP-Glc: flavonoid 3-O-glucosyltransferase (UF3GT), and leucoanthocyanidin dioxygenase (LDOX) in anthocyanin biosynthesis pathway is regulated by MYB75, a R2R3 MYB transcription factor. The production of anthocyanin is known to be promoted by jasmonic acid (JA) in light but not in darkness. The photoreceptors cryptochrome 1 (CRY1), phytochrome B (phyB), and phytochrome A (phyA) are also shown to mediate light promotion of anthocyanin accumulation, respectively, whereas their downstream factor COP1, a master negative regulator of photomorphogensis, represses anthocyanin accumulation. However, whether JA coordinates with photoreceptors in the regulation of anthocyanin accumulation is unknown. Here, we show that under far-red light, JA promotes anthocyanin accumulation in a phyA signaling pathway-dependent manner. The phyA mutant is hyposensitive to jasmonic acid analog methyl jasmonic acid (MeJA) under far-red light. The dominant mutant of MYB75, pap1-D, accumulates significantly higher levels of anthocyanin than wild type under far-red light, whereas knockdown of MYBs (MYB75, MYB90, MYB113, and MYB114) through RNAi significantly reduces MeJA promotion of anthocyanin accumulation. The phyA pap1-D double mutant shows reduced responsiveness to MeJA, similar to phyA mutant under far-red light. In darkness, a mutant allele of cop1, cop1-4, shows enhanced responsiveness to MeJA, but pap1-D mutant is barely responsive to MeJA. Upon MeJA application, the cop1-4 pap1-D double mutant accumulates considerably higher levels of anthocyanin than cop1-4 in darkness. Protein studies indicate that MYB75 protein is stabilized by white light and far-red light. Further gene expression studies suggest that MeJA promotes the expression of DFR, UF3GT, and LDOX genes in a phyA- and MYB75-dependent manner under far-red light. Our findings suggest

  4. α-Lipoic acid inhibits sevoflurane-induced neuronal apoptosis through PI3K/Akt signalling pathway.

    PubMed

    Ma, Rong; Wang, Xiang; Peng, Peipei; Xiong, Jingwei; Dong, Hongquan; Wang, Lixia; Ding, Zhengnian

    2016-01-01

    Sevoflurane is a widely used anaesthetic agent, including in anaesthesia of children and infants. Recent studies indicated that the general anaesthesia might cause the cell apoptosis in the brain. This issue raises the concerns about the neuronal toxicity induced by the application of anaesthetic agents, especially in the infants and young children. In this study, we used Morris water maze, western blotting and immunohistochemistry to elucidate the role of α-lipoic acid in the inhibition of neuronal apoptosis. We found that sevoflurane led to the long-term cognitive impairment in the young rats. This adverse effect may be caused by the neuronal death in the hippocampal region, mediated through PI3K/Akt signalling pathway. We also showed that α-lipoic acid offset the effect of sevoflurane on the neuronal apoptosis and cognitive dysfunction. This study elucidated the potential clinical role of α-lipoic acid, providing a promising way in the prevention and treatment of long-term cognitive impairment induced by sevoflurane general anesthesia.

  5. Induction of G2/M arrest by pseudolaric acid B is mediated by activation of the ATM signaling pathway

    PubMed Central

    Meng, Ai-guo; Jiang, Ling-ling

    2009-01-01

    Aim: The aim of this study was to investigate the mechanism of pseudolaric acid B (PLAB)-induced cell cycle arrest in human melanoma SK-28 cells. Methods: Cell growth inhibition was detected by MTT assay, the cell cycle was analyzed by flow cytometry, and protein expression was examined by Western blot analysis. Results: PLAB inhibited the growth of human melanoma cells and induced G2/M arrest in SK-28 cells, accompanied by an up-regulation of Cdc2 phosphorylation and a subsequent down-regulation of Cdc2 expression. Furthermore, PLAB decreased the expression of Cdc25C phosphatase and increased the expression of Wee1 kinase. Meanwhile, a reduction in Cdc2 activity was partly due to induction of the expression of p21waf1/cip1 in a p53-dependent manner. In addition, PLAB activated the checkpoint kinase, Chk2, and increased the expression of p53, two major targets of ATM kinase. These effects were inhibited by caffeine, an ATM kinase inhibitor. We also found that PLAB significantly enhanced ATM kinase activity. Conclusion: Taken together, these results suggest that PLAB induced G2/M arrest in human melanoma cells via a mechanism involving the activation of ATM, and the effect of PLAB on Cdc2 activity was mediated via interactions with the Chk2-Cdc25C and p53 signalling pathways, two distinct downstream pathways of ATM. PLAB may be a promising chemopreventive agent for treating human melanoma. PMID:19305423

  6. PPARα signal pathway gene expression is associated with fatty acid content in yak and cattle longissimus dorsi muscle.

    PubMed

    Qin, W; Liang, C N; Guo, X; Chu, M; Pei, J; Bao, P J; Wu, X Y; Li, T K; Yan, P

    2015-01-01

    Intramuscular fatty acid (FA) is related to meat qualities such as juiciness, tenderness, palatability, and shear force. PPARα plays an important role in lipid metabolism in the liver and skeletal muscle. This study investigated FA composition in yaks and cattle, in order to ascertain whether a correlation between PPARα signal pathway genes as candidate genes and meat FA composition in yaks and cattle exists. Statistical analyses revealed that levels of monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) in yaks were significantly higher than those in cattle (P < 0.01), whereas saturated fatty acid (SFA) levels were significantly lower than those in cattle (P < 0.05). The mRNA expression levels of FABP4 (P < 0.05), SCP2 (P < 0.05), and APOA1 (P < 0.01) in yaks were significantly lower than those in cattle. However, LPL expression in yaks was significantly higher than that in cattle (P < 0.05). In yaks, the expression levels of FABP3 (P < 0.05) and LPL (P < 0.01) were negatively correlated with MUFA, and those of FABP4 and SCD were positively correlated with PUFA (P < 0.01). In cattle, the mRNA level of PLTP was positively correlated with SFA (P < 0.05), and LPL was positively correlated with MUFA (P < 0.05). These results suggest that these genes may participate in the regulation and control of intramuscular FA metabolism in yaks, so they could be used as candidate markers to improve yak meat quality. PMID:26600505

  7. PPARα signal pathway gene expression is associated with fatty acid content in yak and cattle longissimus dorsi muscle.

    PubMed

    Qin, W; Liang, C N; Guo, X; Chu, M; Pei, J; Bao, P J; Wu, X Y; Li, T K; Yan, P

    2015-11-19

    Intramuscular fatty acid (FA) is related to meat qualities such as juiciness, tenderness, palatability, and shear force. PPARα plays an important role in lipid metabolism in the liver and skeletal muscle. This study investigated FA composition in yaks and cattle, in order to ascertain whether a correlation between PPARα signal pathway genes as candidate genes and meat FA composition in yaks and cattle exists. Statistical analyses revealed that levels of monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) in yaks were significantly higher than those in cattle (P < 0.01), whereas saturated fatty acid (SFA) levels were significantly lower than those in cattle (P < 0.05). The mRNA expression levels of FABP4 (P < 0.05), SCP2 (P < 0.05), and APOA1 (P < 0.01) in yaks were significantly lower than those in cattle. However, LPL expression in yaks was significantly higher than that in cattle (P < 0.05). In yaks, the expression levels of FABP3 (P < 0.05) and LPL (P < 0.01) were negatively correlated with MUFA, and those of FABP4 and SCD were positively correlated with PUFA (P < 0.01). In cattle, the mRNA level of PLTP was positively correlated with SFA (P < 0.05), and LPL was positively correlated with MUFA (P < 0.05). These results suggest that these genes may participate in the regulation and control of intramuscular FA metabolism in yaks, so they could be used as candidate markers to improve yak meat quality.

  8. Gallic Acid Induces Necroptosis via TNF–α Signaling Pathway in Activated Hepatic Stellate Cells

    PubMed Central

    Chang, Ya Ju; Hsu, Shih Lan; Liu, Yi Ting; Lin, Yu Hsuan; Lin, Ming Hui; Huang, Shu Jung; Ho, Ja-an Annie; Wu, Li-Chen

    2015-01-01

    Gallic acid (3, 4, 5-trihydroxybenzoic acid, GA), a natural phenolic acid widely found in gallnuts, tea leaves and various fruits, possesses several bioactivities against inflammation, oxidation, and carcinogenicity. The beneficial effect of GA on the reduction of animal hepatofibrosis has been indicated due to its antioxidative property. However, the cytotoxicity of GA autoxidation causing cell death has also been reported. Herein, we postulated that GA might target activated hepatic stellate cells (aHSCs), the cell type responsible for hepatofibrosis, to mitigate the process of fibrosis. The molecular cytotoxic mechanisms that GA exerted on aHSCs were then analyzed. The results indicated that GA elicited aHSC programmed cell death through TNF–α–mediated necroptosis. GA induced significant oxidative stress through the suppression of catalase activity and the depletion of glutathione (GSH). Elevated oxidative stress triggered the production of TNF–α facilitating the undergoing of necroptosis through the up-regulation of key necroptotic regulatory proteins TRADD and receptor-interacting protein 3 (RIP3), and the inactivation of caspase–8. Calmodulin and calpain–1 activation were engaged, which promoted subsequent lysosomal membrane permeabilization (LMP). The TNF–α antagonist (SPD–304) and the RIP1 inhibitor (necrostatin–1, Nec–1) confirmed GA-induced TNFR1–mediated necroptosis. The inhibition of RIP1 by Nec–1 diverted the cell death from necroptosis to apoptosis, as the activation of caspase 3 and the increase of cytochrome c. Collectively, this is the first report indicating that GA induces TNF signaling–triggered necroptosis in aHSCs, which may offer an alternative strategy for the amelioration of liver fibrosis. PMID:25816210

  9. Isp7 is a novel regulator of amino acid uptake in the TOR signaling pathway.

    PubMed

    Laor, Dana; Cohen, Adiel; Pasmanik-Chor, Metsada; Oron-Karni, Varda; Kupiec, Martin; Weisman, Ronit

    2014-03-01

    TOR proteins reside in two distinct complexes, TOR complexes 1 and 2 (TORC1 and TORC2), that are central for the regulation of cellular growth, proliferation, and survival. TOR is also the target for the immunosuppressive and anticancer drug rapamycin. In Schizosaccharomyces pombe, disruption of the TSC complex, mutations in which can lead to the tuberous sclerosis syndrome in humans, results in a rapamycin-sensitive phenotype under poor nitrogen conditions. We show here that the sensitivity to rapamycin is mediated via inhibition of TORC1 and suppressed by overexpression of isp7(+), a member of the family of 2-oxoglutarate-Fe(II)-dependent oxygenase genes. The transcript level of isp7(+) is negatively regulated by TORC1 but positively regulated by TORC2. Yet we find extensive similarity between the transcriptome of cells disrupted for isp7(+) and cells mutated in the catalytic subunit of TORC1. Moreover, Isp7 regulates amino acid permease expression in a fashion similar to that of TORC1 and opposite that of TORC2. Overexpression of isp7(+) induces TORC1-dependent phosphorylation of ribosomal protein Rps6 while inhibiting TORC2-dependent phosphorylation and activation of the AGC-like kinase Gad8. Taken together, our findings suggest a central role for Isp7 in amino acid homeostasis and the presence of isp7(+)-dependent regulatory loops that affect both TORC1 and TORC2.

  10. Chlorogenic acid attenuates lipopolysaccharide-induced mice mastitis by suppressing TLR4-mediated NF-κB signaling pathway.

    PubMed

    Ruifeng, Gao; Yunhe, Fu; Zhengkai, Wei; Ershun, Zhou; Yimeng, Li; Minjun, Yao; Xiaojing, Song; Zhengtao, Yang; Naisheng, Zhang

    2014-04-15

    Chlorogenic acid (CGA), one of the most abundant polyphenols in the diet, has been reported to have potent anti-inflammatory properties. However, the effect of CGA on lipopolysaccharide (LPS)-induced mice mastitis has not been investigated. The purpose of the present study was to elucidate whether CGA could ameliorate the inflammation response in LPS-induced mice mastitis and to clarify the possible mechanism. The mouse model of mastitis was induced by injection of LPS through the duct of mammary gland. CGA was administered intraperitoneally with the dose of 12.5, 25, and 50mg/kg respectively 1h before and 12h after induction of LPS. In this study, the effect of CGA on LPS-induced mice mastitis was assessed through histopathological examination, ELISA assay, and western blot analysis. The results showed that CGA significantly reduced TNF-α, IL-1β, and IL-6 production compared with LPS group. Besides, western blot analysis showed that CGA could inhibit the expression of TLR4 and the phosphorylation of NF-κB and IκB induced by LPS. These results suggested that anti-inflammatory effects of CGA against LPS-induced mastitis may be due to its ability to inhibit TLR4-mediated NF-κB signaling pathway. Therefore, CGA may be a potent therapeutic reagent for the prevention of the immunopathology encountered during Escherichia coli elicited mastitis.

  11. Xenobiotic- and jasmonic acid-inducible signal transduction pathways have become interdependent at the Arabidopsis CYP81D11 promoter.

    PubMed

    Köster, Julia; Thurow, Corinna; Kruse, Kerstin; Meier, Alexander; Iven, Tim; Feussner, Ivo; Gatz, Christiane

    2012-05-01

    Plants modify harmful substances through an inducible detoxification system. In Arabidopsis (Arabidopsis thaliana), chemical induction of the cytochrome P450 gene CYP81D11 and other genes linked to the detoxification program depends on class II TGA transcription factors. CYP81D11 expression is also induced by the phytohormone jasmonic acid (JA) through the established pathway requiring the JA receptor CORONATINE INSENSITIVE1 (COI1) and the JA-regulated transcription factor MYC2. Here, we report that the xenobiotic- and the JA-dependent signal cascades have become interdependent at the CYP81D11 promoter. On the one hand, MYC2 can only activate the expression of CYP81D11 when both the MYC2- and the TGA-binding sites are present in the promoter. On the other hand, the xenobiotic-regulated class II TGA transcription factors can only mediate maximal promoter activity if TGA and MYC2 binding motifs, MYC2, and the JA-isoleucine biosynthesis enzymes DDE2/AOS and JAR1 are functional. Since JA levels and degradation of JAZ1, a repressor of the JA response, are not affected by reactive chemicals, we hypothesize that basal JA signaling amplifies the response to chemical stress. Remarkably, stress-induced expression levels were 3-fold lower in coi1 than in the JA biosynthesis mutant dde2-2, [corrected] revealing that COI1 can contribute to the activation of the promoter in the absence of JA. Moreover, we show that deletion of the MYC2 binding motifs abolishes the JA responsiveness of the promoter but not the responsiveness to COI1. These findings suggest that yet unknown cis-element(s) can mediate COI1-dependent transcriptional activation in the absence of JA.

  12. c9, t11- conjugated linoleic acid induces HCC cell apoptosis and correlation with PPAR-γ signaling pathway

    PubMed Central

    Lu, Guozhong; Zhang, Guoqing; Zheng, Xing; Zeng, Yan; Xu, Ziqi; Zeng, Weichi; Wang, Kebing

    2015-01-01

    Objective: Cis9, trans11 conjugated linoleic acid (c9, t11-CLA.) is one of the most important isomers of conjugated linoleic acid, which have a strong anti-tumor effects. Based on previous studies, we further explored the molecular mechanism of inducing cells apoptosis in human hepatocellular carcinoma cell line HepG2 and Hep3B. Methods: Cell Counting Kit 8 (CCK-8) assay was used to investigate the effects of c9, t11-CLA on cell viability and cell proliferation ability; The effects of c9, t11-CLA on cell apoptosis was analyzed by DNA ladder assay, immuno-fluorescence and flow cytometry, respectively. Apoptotic related gene (Bcl-2, Bcl-XL, Bcl-w, Mcl-1, Bax, Bak, Bad, Bid and Bim), PPAR family member (PPAR-α, PPAR-β and PPAR-γ), and Cox2 mRNA and protein expression were analyzed by RT-PCR and western blotting. ELISA assay was used to detect the content of Caspase-3. Results: Our data were confirmed that c9, t11-CLA could inhibit the HCC cells proliferation ability and decrease the cells viability. RT-PCR and western blotting assay verified that c9, t11-CLA obviously increased the transcription and protein expression levels of PPAR-γ. The synchronism and correlation between PPAR-γ and apoptotic proteins Bcl-2, Bax and Caspase-3 were found with a dose- and time-dependent manner. PPAR-γ inhibitor GW9662 and activator Rosilitazone were further verified that there was cooperative relation between them. Conclusion: In our study, we first report that c9, t11-CLA induces apoptosis in HCC cells by activation of PPARγ-Bcl-2-Caspase-3 signal pathway. These results indicated that c9, t11-CLA will be useful for clinic therapy of anti-tumor and as a new regulator of PPAR-γ in the future. PMID:26885272

  13. Salicylic acid receptors activate jasmonic acid signalling through a non-canonical pathway to promote effector-triggered immunity

    PubMed Central

    Liu, Lijing; Sonbol, Fathi-Mohamed; Huot, Bethany; Gu, Yangnan; Withers, John; Mwimba, Musoki; Yao, Jian; He, Sheng Yang; Dong, Xinnian

    2016-01-01

    It is an apparent conundrum how plants evolved effector-triggered immunity (ETI), involving programmed cell death (PCD), as a major defence mechanism against biotrophic pathogens, because ETI-associated PCD could leave them vulnerable to necrotrophic pathogens that thrive on dead host cells. Interestingly, during ETI, the normally antagonistic defence hormones, salicylic acid (SA) and jasmonic acid (JA) associated with defence against biotrophs and necrotrophs respectively, both accumulate to high levels. In this study, we made the surprising finding that JA is a positive regulator of RPS2-mediated ETI. Early induction of JA-responsive genes and de novo JA synthesis following SA accumulation is activated through the SA receptors NPR3 and NPR4, instead of the JA receptor COI1. We provide evidence that NPR3 and NPR4 may mediate this effect by promoting degradation of the JA transcriptional repressor JAZs. This unique interplay between SA and JA offers a possible explanation of how plants can mount defence against a biotrophic pathogen without becoming vulnerable to necrotrophic pathogens. PMID:27725643

  14. Retroactive Signaling in Short Signaling Pathways

    PubMed Central

    Sepulchre, Jacques-Alexandre; Merajver, Sofía D.; Ventura, Alejandra C.

    2012-01-01

    In biochemical signaling pathways without explicit feedback connections, the core signal transduction is usually described as a one-way communication, going from upstream to downstream in a feedforward chain or network of covalent modification cycles. In this paper we explore the possibility of a new type of signaling called retroactive signaling, offered by the recently demonstrated property of retroactivity in signaling cascades. The possibility of retroactive signaling is analysed in the simplest case of the stationary states of a bicyclic cascade of signaling cycles. In this case, we work out the conditions for which variables of the upstream cycle are affected by a change of the total amount of protein in the downstream cycle, or by a variation of the phosphatase deactivating the same protein. Particularly, we predict the characteristic ranges of the downstream protein, or of the downstream phosphatase, for which a retroactive effect can be observed on the upstream cycle variables. Next, we extend the possibility of retroactive signaling in short but nonlinear signaling pathways involving a few covalent modification cycles. PMID:22848403

  15. Signaling on the endocytic pathway.

    PubMed

    McPherson, P S; Kay, B K; Hussain, N K

    2001-06-01

    Ligand binding to receptor tyrosine kinases and G-protein-coupled receptors initiates signal transduction events and induces receptor endocytosis via clathrin-coated pits and vesicles. While receptor-mediated endocytosis has been traditionally considered an effective mechanism to attenuate ligand-activated responses, more recent studies demonstrate that signaling continues on the endocytic pathway. In fact, certain signaling events, such as the activation of the extracellular signal-regulated kinases, appear to require endocytosis. Protein components of signal transduction cascades can assemble at clathrin coated pits and remain associated with endocytic vesicles following their dynamin-dependent release from the plasma membrane. Thus, endocytic vesicles can function as a signaling compartment distinct from the plasma membrane. These observations demonstrate that endocytosis plays an important role in the activation and propagation of signaling pathways.

  16. Signaling on the endocytic pathway.

    PubMed

    McPherson, P S; Kay, B K; Hussain, N K

    2001-06-01

    Ligand binding to receptor tyrosine kinases and G-protein-coupled receptors initiates signal transduction events and induces receptor endocytosis via clathrin-coated pits and vesicles. While receptor-mediated endocytosis has been traditionally considered an effective mechanism to attenuate ligand-activated responses, more recent studies demonstrate that signaling continues on the endocytic pathway. In fact, certain signaling events, such as the activation of the extracellular signal-regulated kinases, appear to require endocytosis. Protein components of signal transduction cascades can assemble at clathrin coated pits and remain associated with endocytic vesicles following their dynamin-dependent release from the plasma membrane. Thus, endocytic vesicles can function as a signaling compartment distinct from the plasma membrane. These observations demonstrate that endocytosis plays an important role in the activation and propagation of signaling pathways. PMID:11389765

  17. All-trans retinoic acid potentiates cisplatin-induced kidney injury in rats: impact of retinoic acid signaling pathway.

    PubMed

    Elsayed, Abdelrahman M; Abdelghany, Tamer M; Akool, El-Sayed; Abdel-Aziz, Abdel-Aziz H; Abdel-Bakky, Mohamed S

    2016-03-01

    Cisplatin (cis-diammine dichloroplatinum (II), CDDP) is a widely used drug for treatment of various types of cancers. However, CDDP-induced nephrotoxicity remains the main dose-limiting side effect. Retinoids are a group of vitamin A-related compounds that exert their effects through retinoid receptors activation. In this study, we investigated the effect of CDDP treatment on retinoic acid receptor-α (RAR-α) and retinoid X receptor-α (RXR-α) expression. In addition, we investigated the possible modulatory effects of RAR agonist, all-trans retinoic acid (ATRA), on CDDP-induced nephrotoxicity. Rats were treated with saline, DMSO, CDDP, ATRA, or CDDP/ATRA. Twenty-four hours after the last ATRA injection, rats were killed; blood samples were collected; kidneys were dissected; and biochemical, immunohistochemical, and histological examinations were performed. Our results revealed that CDDP treatment significantly increased serum levels of creatinine and urea, with concomitant decrease in serum albumin. Moreover, reduced glutathione (GSH) content as well as superoxide dismutase (SOD) and catalase (CAT) activities were significantly reduced with concurrent increase in kidney malondialdehyde (MDA) content following CDDP treatment. Furthermore, CDDP markedly upregulated tubular RAR-α, RXR-α, fibrin, and inducible nitric oxide synthase (iNOS) protein expression. Although administration of ATRA to control rats did not produce marked alterations in kidney function parameters, administration of ATRA to CDDP-treated rats significantly exacerbated CDDP-induced nephrotoxicity. In addition, CDDP/ATRA co-treatment significantly increased RAR-α, RXR-α, fibrin, and iNOS protein expression compared to CDDP alone. In conclusion, we report, for the first time, the crucial role of retinoid receptors in CDDP-induced nephrotoxicity. Moreover, our findings indicate that co-administration of ATRA with CDDP, although beneficial on the therapeutic effects, their deleterious effects on

  18. Caffeic acid regulates LPS-induced NF-κB activation through NIK/IKK and c-Src/ERK signaling pathways in endothelial cells.

    PubMed

    Kim, So Ra; Jung, Yu Ri; Kim, Dae Hyun; An, Hye Jin; Kim, Mi Kyung; Kim, Nam Deuk; Chung, Hae Young

    2014-04-01

    The redox sensitive, proinflammatory nuclear transcription factor NF-κB plays a key role in inflammation. In a redox state disrupted by oxidative stress, pro-inflammatory genes are upregulated by the activation of NF-κB via diverse kinases. Thus, the search and characterization of new substances that modulate NF-κB are topics of considerable research interest. Caffeic acid is a component of garlic, some fruits, and coffee, and is widely used as a phenolic agent in beverages. In the present study, caffeic acid was examined with respect to the modulation of inflammatory NF-κB activation via the redox-related c-Src/ERK and NIK/IKK pathways via the reduction of oxidative stress. YPEN-1 cells (an endothelial cell line) were used to explore the molecular mechanism underlying the anti-inflammatory effect of caffeic acid by examining its modulation of NF-κB signaling pathway by LPS. Our results show that LPS-induced oxidative stress-related NF-κB activation upregulated pro-inflammatory COX-2, NF-κB targeting gene which were all inhibited effectively by caffeic acid. Our study shows that caffeic acid inhibits the activation of NF-κB via the c-Src/ERK and NIK/IKK signal transduction pathways. Our results indicate that antioxidative effect of caffeic acid and its restoration of redox balance are responsible for its anti-inflammatory action. Thus, the study provides new information regarding the anti-inflammatory properties of caffeic acid and the roles in the regulation of LPS-induced oxidative stress induces alterations in signal transduction pathways.

  19. Ferulic acid regulates the AKT/GSK-3β/CRMP-2 signaling pathway in a middle cerebral artery occlusion animal model.

    PubMed

    Gim, Sang-A; Sung, Jin-Hee; Shah, Fawad-Ali; Kim, Myeong-Ok; Koh, Phil-Ok

    2013-06-01

    Ferulic acid, a component of the plants Angelica sinensis (Oliv.) Diels and Ligusticum chuanxiong Hort, exerts a neuroprotective effect by regulating various signaling pathways. This study showed that ferulic acid treatment prevents the injury-induced increase of collapsin response mediator protein 2 (CRMP-2) in focal cerebral ischemia. Glycogen synthase kinase-3β (GSK-3β) regulates CRMP-2 function through phosphorylation of CRMP-2. Moreover, the pro-apoptotic activity of GSK-3β is inactivated by phosphorylation by Akt. This study investigated whether ferulic acid modulates the expression of CRMP-2 and its upstream targets, Akt and GSK-3β, in focal cerebral ischemia. Male rats were treated immediately with ferulic acid (100 mg/kg, i.v.) or vehicle after middle cerebral artery occlusion (MCAO), and then cerebral cortices were collected 24 hr after MCAO. MCAO resulted in decreased levels of phospho-Akt and phospho-GSK-3β, while ferulic acid treatment prevented the decrease in the levels of these proteins. Moreover, phospho-CRMP-2 and CRMP-2 levels increased during MCAO, whereas ferulic acid attenuated these injury-induced increases. These results demonstrate that ferulic acid regulates the Akt/GSK-3β/CRMP-2 signaling pathway in focal cerebral ischemic injury, thereby protecting against brain injury. PMID:23825478

  20. Analysis of key genes of jasmonic acid mediated signal pathway for defense against insect damages by comparative transcriptome sequencing

    PubMed Central

    Yang, Fengshan; Zhang, Yuliang; Huang, Qixing; Yin, Guohua; Pennerman, Kayla K.; Yu, Jiujiang; Liu, Zhixin; Li, Dafei; Guo, Anping

    2015-01-01

    Corn defense systems against insect herbivory involve activation of genes that lead to metabolic reconfigurations to produce toxic compounds, proteinase inhibitors, oxidative enzymes, and behavior-modifying volatiles. Similar responses occur when the plant is exposed to methyl jasmonate (MeJA). To compare the defense responses between stalk borer feeding and exogenous MeJA on a transcriptional level, we employed deep transcriptome sequencing methods following Ostrinia furnacalis leaf feeding and MeJA leaf treatment. 39,636 genes were found to be differentially expressed with O. furnacalis feeding, MeJA application, and O. furnacalis feeding and MeJA application. Following Gene Ontology enrichment analysis of the up- or down- regulated genes, many were implicated in metabolic processes, stimuli-responsive catalytic activity, and transfer activity. Fifteen genes that indicated significant changes in the O. furnacalis feeding group: LOX1, ASN1, eIF3, DXS, AOS, TIM, LOX5, BBTI2, BBTI11, BBTI12, BBTI13, Cl-1B, TPS10, DOX, and A20/AN1 were found to almost all be involved in jasmonate defense signaling pathways. All of the data demonstrate that the jasmonate defense signal pathway is a major defense signaling pathways of Asian corn borer’s defense against insect herbivory. The transcriptome data are publically available at NCBI SRA: SRS965087. PMID:26560755

  1. Analysis of key genes of jasmonic acid mediated signal pathway for defense against insect damages by comparative transcriptome sequencing.

    PubMed

    Yang, Fengshan; Zhang, Yuliang; Huang, Qixing; Yin, Guohua; Pennerman, Kayla K; Yu, Jiujiang; Liu, Zhixin; Li, Dafei; Guo, Anping

    2015-01-01

    Corn defense systems against insect herbivory involve activation of genes that lead to metabolic reconfigurations to produce toxic compounds, proteinase inhibitors, oxidative enzymes, and behavior-modifying volatiles. Similar responses occur when the plant is exposed to methyl jasmonate (MeJA). To compare the defense responses between stalk borer feeding and exogenous MeJA on a transcriptional level, we employed deep transcriptome sequencing methods following Ostrinia furnacalis leaf feeding and MeJA leaf treatment. 39,636 genes were found to be differentially expressed with O. furnacalis feeding, MeJA application, and O. furnacalis feeding and MeJA application. Following Gene Ontology enrichment analysis of the up- or down- regulated genes, many were implicated in metabolic processes, stimuli-responsive catalytic activity, and transfer activity. Fifteen genes that indicated significant changes in the O. furnacalis feeding group: LOX1, ASN1, eIF3, DXS, AOS, TIM, LOX5, BBTI2, BBTI11, BBTI12, BBTI13, Cl-1B, TPS10, DOX, and A20/AN1 were found to almost all be involved in jasmonate defense signaling pathways. All of the data demonstrate that the jasmonate defense signal pathway is a major defense signaling pathways of Asian corn borer's defense against insect herbivory. The transcriptome data are publically available at NCBI SRA: SRS965087.

  2. Analysis of key genes of jasmonic acid mediated signal pathway for defense against insect damages by comparative transcriptome sequencing.

    PubMed

    Yang, Fengshan; Zhang, Yuliang; Huang, Qixing; Yin, Guohua; Pennerman, Kayla K; Yu, Jiujiang; Liu, Zhixin; Li, Dafei; Guo, Anping

    2015-01-01

    Corn defense systems against insect herbivory involve activation of genes that lead to metabolic reconfigurations to produce toxic compounds, proteinase inhibitors, oxidative enzymes, and behavior-modifying volatiles. Similar responses occur when the plant is exposed to methyl jasmonate (MeJA). To compare the defense responses between stalk borer feeding and exogenous MeJA on a transcriptional level, we employed deep transcriptome sequencing methods following Ostrinia furnacalis leaf feeding and MeJA leaf treatment. 39,636 genes were found to be differentially expressed with O. furnacalis feeding, MeJA application, and O. furnacalis feeding and MeJA application. Following Gene Ontology enrichment analysis of the up- or down- regulated genes, many were implicated in metabolic processes, stimuli-responsive catalytic activity, and transfer activity. Fifteen genes that indicated significant changes in the O. furnacalis feeding group: LOX1, ASN1, eIF3, DXS, AOS, TIM, LOX5, BBTI2, BBTI11, BBTI12, BBTI13, Cl-1B, TPS10, DOX, and A20/AN1 were found to almost all be involved in jasmonate defense signaling pathways. All of the data demonstrate that the jasmonate defense signal pathway is a major defense signaling pathways of Asian corn borer's defense against insect herbivory. The transcriptome data are publically available at NCBI SRA: SRS965087. PMID:26560755

  3. Phenylbutyric acid induces the cellular senescence through an Akt/p21{sup WAF1} signaling pathway

    SciTech Connect

    Kim, Hag Dong; Jang, Chang-Young; Choe, Jeong Min; Sohn, Jeongwon; Kim, Joon

    2012-06-01

    Highlights: Black-Right-Pointing-Pointer Phenylbutyric acid induces cellular senescence. Black-Right-Pointing-Pointer Phenylbutyric acid activates Akt kinase. Black-Right-Pointing-Pointer The knockdown of PERK also can induce cellular senescence. Black-Right-Pointing-Pointer Akt/p21{sup WAF1} pathway activates in PERK knockdown induced cellular senescence. -- Abstract: It has been well known that three sentinel proteins - PERK, ATF6 and IRE1 - initiate the unfolded protein response (UPR) in the presence of misfolded or unfolded proteins in the ER. Recent studies have demonstrated that upregulation of UPR in cancer cells is required to survive and proliferate. Here, we showed that long exposure to 4-phenylbutyric acid (PBA), a chemical chaperone that can reduce retention of unfolded and misfolded proteins in ER, induced cellular senescence in cancer cells such as MCF7 and HT1080. In addition, we found that treatment with PBA activates Akt, which results in p21{sup WAF1} induction. Interestingly, the depletion of PERK but not ATF6 and IRE1 also induces cellular senescence, which was rescued by additional depletion of Akt. This suggests that Akt pathway is downstream of PERK in PBA induced cellular senescence. Taken together, these results show that PBA induces cellular senescence via activation of the Akt/p21{sup WAF1} pathway by PERK inhibition.

  4. Cancer stem cell signaling pathways.

    PubMed

    Matsui, William H

    2016-09-01

    Tissue development and homeostasis are governed by the actions of stem cells. Multipotent cells are capable of self-renewal during the course of one's lifetime. The accurate and appropriate regulation of stem cell functions is absolutely critical for normal biological activity. Several key developmental or signaling pathways have been shown to play essential roles in this regulatory capacity. Specifically, the Janus-activated kinase/signal transducer and activator of transcription, Hedgehog, Wnt, Notch, phosphatidylinositol 3-kinase/phosphatase and tensin homolog, and nuclear factor-κB signaling pathways have all been shown experimentally to mediate various stem cell properties, such as self-renewal, cell fate decisions, survival, proliferation, and differentiation. Unsurprisingly, many of these crucial signaling pathways are dysregulated in cancer. Growing evidence suggests that overactive or abnormal signaling within and among these pathways may contribute to the survival of cancer stem cells (CSCs). CSCs are a relatively rare population of cancer cells capable of self-renewal, differentiation, and generation of serially transplantable heterogeneous tumors of several types of cancer. PMID:27611937

  5. Transcriptional regulation of the IGF signaling pathway by amino acids and insulin-like growth factors during myogenesis in Atlantic salmon.

    PubMed

    Bower, Neil I; Johnston, Ian A

    2010-01-01

    The insulin-like growth factor signalling pathway is an important regulator of skeletal muscle growth. We examined the mRNA expression of components of the insulin-like growth factor (IGF) signalling pathway as well as Fibroblast Growth Factor 2 (FGF2) during maturation of myotubes in primary cell cultures isolated from fast myotomal muscle of Atlantic salmon (Salmo salar). The transcriptional regulation of IGFs and IGFBP expression by amino acids and insulin-like growth factors was also investigated. Proliferation of cells was 15% d(-1) at days 2 and 3 of the culture, increasing to 66% d(-1) at day 6. Three clusters of elevated gene expression were observed during the maturation of the culture associated with mono-nucleic cells (IGFBP5.1 and 5.2, IGFBP-6, IGFBP-rP1, IGFBP-2.2 and IGF-II), the initial proliferation phase (IGF-I, IGFBP-4, FGF2 and IGF-IRb) and terminal differentiation and myotube production (IGF2R, IGF-IRa). In cells starved of amino acids and serum for 72 h, IGF-I mRNA decreased 10-fold which was reversed by amino acid replacement. Addition of IGF-I and amino acids to starved cells resulted in an 18-fold increase in IGF-I mRNA indicating synergistic effects and the activation of additional pathway(s) leading to IGF-I production via a positive feedback mechanism. IGF-II, IGFBP-5.1 and IGFBP-5.2 expression was unchanged in starved cells, but increased with amino acid replacement. Synergistic increases in expression of IGFBP5.2 and IGFBP-4, but not IGFBP5.1 were observed with addition of IGF-I, IGF-II or insulin and amino acids to the medium. IGF-I and IGF-II directly stimulated IGFBP-6 expression, but not when amino acids were present. These findings indicate that amino acids alone are sufficient to stimulate myogenesis in myoblasts and that IGF-I production is controlled by both endocrine and paracrine pathways. A model depicting the transcriptional regulation of the IGF pathway in Atlantic salmon muscle following feeding is proposed. PMID:20559434

  6. Caffeic Acid Phenethylester Increases Stress Resistance and Enhances Lifespan in Caenorhabditis elegans by Modulation of the Insulin-Like DAF-16 Signalling Pathway

    PubMed Central

    Havermann, Susannah; Chovolou, Yvonni; Humpf, Hans-Ulrich; Wätjen, Wim

    2014-01-01

    CAPE is an active constituent of propolis which is widely used in traditional medicine. This hydroxycinnamic acid derivate is a known activator of the redox-active Nrf2 signalling pathway in mammalian cells. We used C. elegans to investigate the effects of this compound on accumulation of reactive oxygen species and the modulation of the pivotal redox-active pathways SKN-1 and DAF-16 (homologues of Nrf2 and FoxO, respectively) in this model organism; these results were compared to the effects in Hct116 human colon carcinoma cells. CAPE exerts a strong antioxidative effect in C. elegans: The increase of reactive oxygen species induced by thermal stress was diminished by about 50%. CAPE caused a nuclear translocation of DAF-16, but not SKN-1. CAPE increased stress resistance of the nematode against thermal stress and finally a prolongation of the median and maximum lifespan by 9 and 17%, respectively. This increase in stress resistance and lifespan was dependent on DAF-16 as shown in experiments using a DAF-16 loss of function mutant strain. Life prolongation was retained under SKN-1 RNAi conditions showing that the effect is SKN-1 independent. The results of CAPE obtained in C. elegans differed from the results obtained in Hct116 colon carcinoma cells: CAPE also caused strong antioxidative effects in the mammalian cells, but no activation of the FoxO4 signalling pathway was detectable. Instead, an activation of the Nrf2 signalling pathway was shown by luciferase assay and western blots. CONCLUSION: CAPE activates the insulin-like DAF-16, but not the SKN-1 signalling pathway in C. elegans and therefore enhances the stress resistance and lifespan of this organism. Since modulation of the DAF-16 pathway was found to be a pivotal effect of CAPE in C. elegans, this has to be taken into account for the investigation of the molecular mechanisms of the traditional use of propolis. PMID:24964141

  7. Lobaric Acid Inhibits VCAM-1 Expression in TNF-α-Stimulated Vascular Smooth Muscle Cells via Modulation of NF-κB and MAPK Signaling Pathways

    PubMed Central

    Kwon, Ii-Seul; Yim, Joung-Han; Lee, Hong-Kum; Pyo, Suhkneung

    2016-01-01

    Lichens have been known to possess multiple biological activities, including anti-proliferative and anti-inflammatory activities. Vascular cell adhesion molecule-1 (VCAM-1) may play a role in the development of atherosclerosis. Hence, VCAM-1 is a possible therapeutic target in the treatment of the inflammatory disease. However, the effect of lobaric acid on VCAM-1 has not yet been investigated and characterized. For this study, we examined the effect of lobaric acid on the inhibition of VCAM-1 in tumor necrosis factor-alpha (TNF-α)-stimulated mouse vascular smooth muscle cells. Western blot and ELISA showed that the increased expression of VCAM-1 by TNF-α was significantly suppressed by the pre-treatment of lobaric acid (0.1–10 μg/ml) for 2 h. Lobaric acid abrogated TNF-α-induced NF-κB activity through preventing the degradation of IκB and phosphorylation of extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK), and p38 mitogen activated protein (MAP) kinase. Lobaric acid also inhibited the expression of TNF-α receptor 1 (TNF-R1). Overall, our results suggest that lobaric acid inhibited VCAM-1 expression through the inhibition of p38, ERK, JNK and NF-κB signaling pathways, and downregulation of TNF-R1 expression. Therefore, it is implicated that lobaric acid may suppress inflammation by altering the physiology of the atherosclerotic lesion. PMID:26759698

  8. In silico study of interaction between rice proteins enhanced disease susceptibility 1 and phytoalexin deficient 4, the regulators of salicylic acid signalling pathway.

    PubMed

    Singh, Indra; Shah, Kavita

    2012-07-01

    Enhanced disease susceptibility 1 (EDS1), a plant-specific protein has homology with the eukaryotic lipase in their N-terminal halves and a unique domain at its C-termini. EDS1 is known to be an important regulator of biotic stress and an essential component of basal immunity. EDS1 interacts with its positive co-regulator phytoalexin deficient 4 (PAD4), resulting in mobilization of the salicylic acid defence pathway. Limited information regarding this interaction in rice is available. To study this interaction, a model of EDS1 and PAD4 proteins from rice was generated and validated with Accelrys DS software version 3.1 using bioinformatics interface. The in silico docking between the two proteins showed a significant protein-protein interaction between rice EDS1 and PAD4, suggesting that they form a dimeric protein complex, which, similar to that in Arabidopsis, is perhaps also important for triggering the salicylic acid signalling pathway in plants.

  9. Effect of methacrylic acid beads on the sonic hedgehog signaling pathway and macrophage polarization in a subcutaneous injection mouse model.

    PubMed

    Lisovsky, Alexandra; Zhang, David K Y; Sefton, Michael V

    2016-08-01

    Poly(methacrylic acid-co-methyl methacrylate) (MAA) beads promote a vascular regenerative response when used in diabetic wound healing. Previous studies reported that MAA beads modulated the expression of sonic hedgehog (Shh) and inflammation related genes in diabetic wounds. The aim of this work was to follow up on these observations in a subcutaneous injection model to study the host response in the absence of the confounding factors of diabetic wound healing. In this model, MAA beads improved vascularization in healthy mice of both sexes compared to control poly(methyl methacrylate) (MM) beads, with a stronger effect seen in males than females. MAA-induced vessels were perfusable, as evidenced from the CLARITY-processed images. In Shh-Cre-eGFP/Ptch1-LacZ non-diabetic transgenic mice, the increased vessel formation was accompanied by a higher density of cells expressing GFP (Shh) and β-Gal (patched 1, Ptch1) suggesting MAA enhanced the activation of the Shh pathway. Ptch1 is the Shh receptor and a target of the pathway. MAA beads also modulated the inflammatory cell infiltrate in CD1 mice: more neutrophils and more macrophages were noted with MAA relative to MM beads at days 1 and 7, respectively. In addition, MAA beads biased macrophages towards a MHCII-CD206+ ("M2") polarization state. This study suggests that the Shh pathway and an altered inflammatory response are two elements of the complex mechanism whereby MAA-based biomaterials effect vascular regeneration. PMID:27264502

  10. All-Trans Retinoic Acid Induces Proliferation, Survival, and Migration in A549 Lung Cancer Cells by Activating the ERK Signaling Pathway through a Transcription-Independent Mechanism

    PubMed Central

    Quintero Barceinas, Reyna Sara; García-Regalado, Alejandro; Aréchaga-Ocampo, Elena; Villegas-Sepúlveda, Nicolás; González-De la Rosa, Claudia Haydée

    2015-01-01

    All-trans retinoic acid (ATRA) has been used as an antineoplastic because of its ability to promote proliferation, inhibition, and differentiation, primarily in leukemia; however, in other types of cancer, such as lung cancer, treatment with ATRA is restricted because not all the patients experience the same results. The ERK signaling pathway is dysregulated in cancer cells, including lung cancer, and this dysregulation promotes proliferation and cell invasion. In this study, we demonstrate that treatment with ATRA can activate the ERK signaling pathway by a transcription-independent mechanism through a signaling cascade that involves RARα and PI3K, promoting growth, survival, and migration in lung cancer cells. Until now, this mechanism was unknown in lung cancer cells. The inhibition of the ERK signaling pathway restores the beneficial effects of ATRA, reduces proliferation, increases apoptosis, and blocks the cell migration process in lung cancer cells. In conclusion, our results suggest that the combination of ATRA with ERK inhibitor in clinical trials for lung cancer is warranted. PMID:26557664

  11. Pseudolaric acid B exerts antitumor activity via suppression of the Akt signaling pathway in HeLa cervical cancer cells.

    PubMed

    Li, Mingqun; Hong, Li

    2015-08-01

    Pseudolaric acid B (PAB) is a diterpene acid isolated from the bark of the root and trunk of Pseudolarix kaempferi Gordon (Pinaceae), which has demonstrated cytotoxic effects against various types of cancer. However, the mechanisms underlying the anticancer effects of PAB have remained to be elucidated. In the present study, the effects of PAB on the viability and apoptosis of HeLa cells were investigated by MTT assay, flow cytometric analysis of Annexin V-fluorescein isothiocyanate/propidium iodide staining, Rhodamine 123 staining and western blot analysis. The results demonstrated that PAB had antiproliferative and apoptosis-inducing effects on HeLa cells. PAB markedly inhibited HeLa cell viability in a time- and concentration-dependent manner. Flow cytometric analysis indicated that PAB induced apoptosis in HeLa cells in a dose-dependent manner. Treatment with PAB suppressed the expression of anti-apoptotic factor B cell lymphoma-2, and promoted the expression of pro-apoptotic factor Bcl-2-associated X protein. In addition, PAB induced an increase in Caspase-3 activity and loss of mitochondrial membrane potential, suggesting that this apoptosis may be mediated by mitochondrial pathways. Furthermore, the results of western blot analysis indicated that PAB was able to reduce Akt phosphorylation, thereby inhibiting the Akt pathway. These results suggested that PAB inhibited cell proliferation and induced apoptosis in HeLa cells, and that the anti-tumor effects of PAB were associated with inhibition of the Akt pathway. In conclusion, the results of the present study suggested that PAB may represent a novel therapeutic strategy for the treatment of human cervical cancer. However, additional studies are required to investigate the underlying apoptotic mechanisms.

  12. Regulation of Monocarboxylic Acid Transporter 1 Trafficking by the Canonical Wnt/β-Catenin Pathway in Rat Brain Endothelial Cells Requires Cross-talk with Notch Signaling.

    PubMed

    Liu, Zejian; Sneve, Mary; Haroldson, Thomas A; Smith, Jeffrey P; Drewes, Lester R

    2016-04-01

    The transport of monocarboxylate fuels such as lactate, pyruvate, and ketone bodies across brain endothelial cells is mediated by monocarboxylic acid transporter 1 (MCT1). Although the canonical Wnt/β-catenin pathway is required for rodent blood-brain barrier development and for the expression of associated nutrient transporters, the role of this pathway in the regulation of brain endothelial MCT1 is unknown. Here we report expression of nine members of the frizzled receptor family by the RBE4 rat brain endothelial cell line. Furthermore, activation of the canonical Wnt/β-catenin pathway in RBE4 cells via nuclear β-catenin signaling with LiCl does not alter brain endothelialMct1mRNA but increases the amount of MCT1 transporter protein. Plasma membrane biotinylation studies and confocal microscopic examination of mCherry-tagged MCT1 indicate that increased transporter results from reduced MCT1 trafficking from the plasma membrane via the endosomal/lysosomal pathway and is facilitated by decreased MCT1 ubiquitination following LiCl treatment. Inhibition of the Notch pathway by the γ-secretase inhibitorN-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycinet-butyl ester negated the up-regulation of MCT1 by LiCl, demonstrating a cross-talk between the canonical Wnt/β-catenin and Notch pathways. Our results are important because they show, for the first time, the regulation of MCT1 in cerebrovascular endothelial cells by the multifunctional canonical Wnt/β-catenin and Notch signaling pathways.

  13. Adipocyte amino acid sensing controls adult germline stem cell number via the amino acid response pathway and independently of Target of Rapamycin signaling in Drosophila

    PubMed Central

    Armstrong, Alissa R.; Laws, Kaitlin M.; Drummond-Barbosa, Daniela

    2014-01-01

    How adipocytes contribute to the physiological control of stem cells is a critical question towards understanding the link between obesity and multiple diseases, including cancers. Previous studies have revealed that adult stem cells are influenced by whole-body physiology through multiple diet-dependent factors. For example, nutrient-dependent pathways acting within the Drosophila ovary control the number and proliferation of germline stem cells (GSCs). The potential role of nutrient sensing by adipocytes in modulating stem cells in other organs, however, remains largely unexplored. Here, we report that amino acid sensing by adult adipocytes specifically modulates the maintenance of GSCs through a Target of Rapamycin-independent mechanism. Instead, reduced amino acid levels and the consequent increase in uncoupled tRNAs trigger activation of the GCN2-dependent amino acid response pathway within adipocytes, causing increased rates of GSC loss. These studies reveal a new step in adipocyte-stem cell crosstalk. PMID:25359724

  14. Oleanolic acid supplement attenuates liquid fructose-induced adipose tissue insulin resistance through the insulin receptor substrate-1/phosphatidylinositol 3-kinase/Akt signaling pathway in rats

    SciTech Connect

    Li, Ying; Wang, Jianwei; Gu, Tieguang; Yamahara, Johji; Li, Yuhao

    2014-06-01

    Oleanolic acid, a triterpenoid contained in more than 1620 plants including various fruits and foodstuffs, has numerous metabolic effects, such as hepatoprotection. However, its underlying mechanisms remain poorly understood. Adipose tissue insulin resistance (Adipo-IR) may contribute to the development and progress of metabolic abnormalities through release of excessive free fatty acids from adipose tissue. This study investigated the effect of oleanolic acid on Adipo-IR. The results showed that supplement with oleanolic acid (25 mg/kg, once daily, by oral gavage) over 10 weeks attenuated liquid fructose-induced increase in plasma insulin concentration and the homeostasis model assessment of insulin resistance (HOMA-IR) index in rats. Simultaneously, oleanolic acid reversed the increase in the Adipo-IR index and plasma non-esterified fatty acid concentrations during the oral glucose tolerance test assessment. In white adipose tissue, oleanolic acid enhanced mRNA expression of the genes encoding insulin receptor, insulin receptor substrate (IRS)-1 and phosphatidylinositol 3-kinase. At the protein level, oleanolic acid upregulated total IRS-1 expression, suppressed the increased phosphorylated IRS-1 at serine-307, and restored the increased phosphorylated IRS-1 to total IRS-1 ratio. In contrast, phosphorylated Akt to total Akt ratio was increased. Furthermore, oleanolic acid reversed fructose-induced decrease in phosphorylated-Akt/Akt protein to plasma insulin concentration ratio. However, oleanolic acid did not affect IRS-2 mRNA expression. Therefore, these results suggest that oleanolic acid supplement ameliorates fructose-induced Adipo-IR in rats via the IRS-1/phosphatidylinositol 3-kinase/Akt pathway. Our findings may provide new insights into the mechanisms of metabolic actions of oleanolic acid. - Highlights: • Adipose insulin resistance (Adipo-IR) contributes to metabolic abnormalities. • We investigated the effect of oleanolic acid (OA) on adipo-IR in

  15. Pharmacology of intracellular signalling pathways

    PubMed Central

    Nahorski, Stefan R

    2006-01-01

    This article provides a brief and somewhat personalized review of the dramatic developments that have occurred over the last 45 years in our understanding of intracellular signalling pathways associated with G-protein-coupled receptor activation. Signalling via cyclic AMP, the phosphoinositides and Ca2+ is emphasized and these systems have already been revealed as new pharmacological targets. The therapeutic benefits of most of such targets are, however, yet to be realized, but it is certain that the discipline of pharmacology needs to widen its boundaries to meet these challenges in the future. PMID:16402119

  16. Signaling Pathways in Cartilage Repair

    PubMed Central

    Mariani, Erminia; Pulsatelli, Lia; Facchini, Andrea

    2014-01-01

    In adult healthy cartilage, chondrocytes are in a quiescent phase characterized by a fine balance between anabolic and catabolic activities. In ageing, degenerative joint diseases and traumatic injuries of cartilage, a loss of homeostatic conditions and an up-regulation of catabolic pathways occur. Since cartilage differentiation and maintenance of homeostasis are finely tuned by a complex network of signaling molecules and biophysical factors, shedding light on these mechanisms appears to be extremely relevant for both the identification of pathogenic key factors, as specific therapeutic targets, and the development of biological approaches for cartilage regeneration. This review will focus on the main signaling pathways that can activate cellular and molecular processes, regulating the functional behavior of cartilage in both physiological and pathological conditions. These networks may be relevant in the crosstalk among joint compartments and increased knowledge in this field may lead to the development of more effective strategies for inducing cartilage repair. PMID:24837833

  17. Distinct abscisic acid signaling pathways for modulation of guard cell versus mesophyll cell potassium channels revealed by expression studies in Xenopus laevis oocytes

    NASA Technical Reports Server (NTRS)

    Sutton, F.; Paul, S. S.; Wang, X. Q.; Assmann, S. M.; Evans, M. L. (Principal Investigator)

    2000-01-01

    Regulation of guard cell ion transport by abscisic acid (ABA) and in particular ABA inhibition of a guard cell inward K(+) current (I(Kin)) is well documented. However, little is known concerning ABA effects on ion transport in other plant cell types. Here we applied patch clamp techniques to mesophyll cell protoplasts of fava bean (Vicia faba cv Long Pod) plants and demonstrated ABA inhibition of an outward K(+) current (I(Kout)). When mesophyll cell protoplast mRNA (mesophyll mRNA) was expressed in Xenopus laevis oocytes, I(Kout) was generated that displayed similar properties to I(Kout) observed from direct analysis of mesophyll cell protoplasts. I(Kout) expressed by mesophyll mRNA-injected oocytes was inhibited by ABA, indicating that the ABA signal transduction pathway observed in mesophyll cells was preserved in the frog oocytes. Co-injection of oocytes with guard cell protoplast mRNA and cRNA for KAT1, an inward K(+) channel expressed in guard cells, resulted in I(Kin) that was similarly inhibited by ABA. However, oocytes co-injected with mesophyll mRNA and KAT1 cRNA produced I(Kin) that was not inhibited by ABA. These results demonstrate that the mesophyll-encoded signaling mechanism could not substitute for the guard cell pathway. These findings indicate that mesophyll cells and guard cells use distinct and different receptor types and/or signal transduction pathways in ABA regulation of K(+) channels.

  18. Protective Effects of Gallic Acid Against NiSO4-Induced Toxicity Through Down-Regulation of the Ras/ERK Signaling Pathway in Beas-2B Cells

    PubMed Central

    An, Xuejun; Zhou, Aijia; Yang, Yue; Wang, Yue; Xin, Rui; Tian, Chao; Wu, Yonghui

    2016-01-01

    Background This study aimed to explore the preventive effects of gallic acid (GA) on the toxicity induced by NiSO4 in Beas-2B cells. Material/Methods Beas-2B cell viability was measured by MTT assay. The degree of oxidative stress was detected by measuring the levels of reactive oxygen species (ROS) and lipid peroxide (LPO). The rate of apoptosis was measured by flow cytometry. Ras/ERK-related protein levels were analyzed by Western blot analysis, which including Ras, ERK, c-Myc, PARP, and PARP cleavage. Results MTT assay showed that NiSO4 induced cytotoxicity, while GA had a protective role against toxicity. Additionally, GA could reduce the apoptotic cell number and the level of ROS in Beas-2B cells induced by NiSO4. Western blot analysis demonstrated that NiSO4 could up-regulate the related protein in the Ras/ERK signaling pathway. Furthermore, we observed that GA could alleviate the toxicity of NiSO4 through regulating protein changes in the Ras/ERK signaling pathway. Conclusions Preventive effects of GA on NiSO4-induced cytotoxicity in Beas-2B cells may be through the Ras/ERK signaling pathways. PMID:27676106

  19. Distinct abscisic acid signaling pathways for modulation of guard cell versus mesophyll cell potassium channels revealed by expression studies in Xenopus laevis oocytes.

    PubMed

    Sutton, F; Paul, S S; Wang, X Q; Assmann, S M

    2000-09-01

    Regulation of guard cell ion transport by abscisic acid (ABA) and in particular ABA inhibition of a guard cell inward K(+) current (I(Kin)) is well documented. However, little is known concerning ABA effects on ion transport in other plant cell types. Here we applied patch clamp techniques to mesophyll cell protoplasts of fava bean (Vicia faba cv Long Pod) plants and demonstrated ABA inhibition of an outward K(+) current (I(Kout)). When mesophyll cell protoplast mRNA (mesophyll mRNA) was expressed in Xenopus laevis oocytes, I(Kout) was generated that displayed similar properties to I(Kout) observed from direct analysis of mesophyll cell protoplasts. I(Kout) expressed by mesophyll mRNA-injected oocytes was inhibited by ABA, indicating that the ABA signal transduction pathway observed in mesophyll cells was preserved in the frog oocytes. Co-injection of oocytes with guard cell protoplast mRNA and cRNA for KAT1, an inward K(+) channel expressed in guard cells, resulted in I(Kin) that was similarly inhibited by ABA. However, oocytes co-injected with mesophyll mRNA and KAT1 cRNA produced I(Kin) that was not inhibited by ABA. These results demonstrate that the mesophyll-encoded signaling mechanism could not substitute for the guard cell pathway. These findings indicate that mesophyll cells and guard cells use distinct and different receptor types and/or signal transduction pathways in ABA regulation of K(+) channels. PMID:10982437

  20. Proinsulin C-peptide antagonizes the profibrotic effects of TGF-beta1 via up-regulation of retinoic acid and HGF-related signaling pathways.

    PubMed

    Hills, Claire E; Willars, Gary B; Brunskill, Nigel J

    2010-04-01

    Novel signaling roles for C-peptide have recently been discovered with evidence that it can ameliorate complications of type 1 diabetes. Here we sought to identify new pathways regulated by C-peptide of relevance to the pathophysiology of diabetic nephropathy. Microarray analysis was performed to identify genes regulated by either C-peptide and/or TGF-beta1 in a human proximal tubular cell line, HK-2. Expression of retinoic acid receptor beta (RARbeta), hepatocyte growth factor (HGF), cellular retinoic acid-binding protein II (CRABPII), vimentin, E-cadherin, Snail, and beta-catenin was assessed by immunoblotting. The cellular localization of vimentin and beta-catenin was determined by immunocytochemistry. Changes in cell morphology were assessed by phase contrast microscopy. Gene expression profiling demonstrated differential expression of 953 and 1458 genes after C-peptide exposure for 18 h or 48 h, respectively. From these, members of the antifibrotic retinoic acid (RA)- and HGF-signaling pathways were selected. Immunoblotting demonstrated that C-peptide increased RARbeta, CRABPII, and HGF. We confirmed a role for RA in reversal of TGF-beta1-induced changes associated with epithelial-mesenchymal transition, including expression changes in Snail, E-cadherin, vimetin, and redistribution of beta-catenin. Importantly, these TGF-beta1-induced changes were inhibited by C-peptide. Further, effects of TGF-beta1 on Snail and E-cadherin expression were blocked by HGF, and inhibitory effects of C-peptide were removed by blockade of HGF activity. This study identifies a novel role for HGF as an effector of C-peptide, possibly via an RA-signaling pathway, highlighting C-peptide as a potential therapy for diabetic nephropathy. PMID:20197308

  1. Antagonism between abscisic acid and ethylene in Arabidopsis acts in parallel with the reciprocal regulation of their metabolism and signaling pathways.

    PubMed

    Cheng, Wan-Hsing; Chiang, Ming-Hau; Hwang, San-Gwang; Lin, Pei-Chi

    2009-09-01

    Although abscisic acid (ABA) and ethylene have antagonistic functions in the control of plant growth and development, including seed germination and early seedling development, it remains unknown whether a convergent point exists between these two signaling pathways or whether they operate in parallel in Arabidopsis thaliana. To elucidate this issue, four ethylene mutants, ctr1, ein2, ein3, and ein6, were crossed with aba2 (also known as gin1-3) to generate double mutants. Genetic epistasis analysis revealed that all of the resulting double mutants displayed aba2 mutant phenotypes with a small plant size and wiltiness when grown in soil or on agar plates. Further ethylene sensitivity or triple response analyses demonstrated that these double mutants also retained the ctr1 or ein mutant phenotypes, showing ethylene constitutive triple and insensitive responses, respectively. Our current data therefore demonstrate that ABA and ethylene act in parallel, at least in primary signal transduction pathways. Moreover, by microarray analysis we found that an ACC oxidase (ACO) was significantly upregulated in the aba2 mutant, whereas the 9-CIS-EPOXYCAROTENOID DIOXYGENASE 3 (NCED3) gene in ein2 was upregulated, and both the ABSCISIC ACID INSENSITIVE1 (ABI1) and cytochrome P450, family 707, subfamily A, polypeptide 2 (CYP707A2) genes in etr1-1 were downregulated. These data further suggest that ABA and ethylene may control the hormonal biosynthesis, catabolism, or signaling of each other to enhance their antagonistic effects upon seed germination and early seedling growth.

  2. Carnosic acid nanoparticles suppress liver ischemia/reperfusion injury by inhibition of ROS, Caspases and NF-κB signaling pathway in mice.

    PubMed

    Li, Hui; Sun, Jian-Jun; Chen, Guo-Yong; Wang, Wei-Wei; Xie, Zhan-Tao; Tang, Gao-Feng; Wei, Si-Dong

    2016-08-01

    Living donor liver transplantation (LDLT) requires ischemia/reperfusion (I/R), which can lead to early graft injury. However, the detailed molecular mechanism of I/R injury remains unclear. Carnosic acid, as a phenolic diterpene with function of anti-inflammation, anti-cancer, anti-bacterial, anti-diabetic, as well as neuroprotective properties, is produced by many species from Lamiaceae family. Nanoparticulate drug delivery systems have been known to better the bioavailability of drugs on intranasal administration compared with only drug solutions. Administration of carnosic acid nanoparticles was thought to be sufficient to lead to considerable inhibition of liver injury progression induced by ischemia/reperfusion. In our study, liver ischemia/reperfusion injury was established successfully with C57BL/6 animal model. 10 and 20mg/kg carnosic acid nanoparticles were injected to mice for five days prior to ischemia. After liver ischemia/reperfusion, the levels of serum AST, ALT and APL were increased, which was attenuated by pre-treatment with carnosic acid nanoparticles. In addition, carnosic acid nanoparticles inhibited ROS production via its related signals regulation. And carnosic acid nanoparticles also suppressed the ischemia/reperfusion-induced up-regulation in the pro-apoptotic protein and mRNA levels of Bax, Cyto-c, Apaf-1 and Caspase-9/3 while increased ischemia/reperfusion-induced decrease of anti-apoptotic factor of Bcl-2. Further, ischemia/reperfusion-induced inflammation was also inhibited for carnosic acid nanoparticles administration via inactivating NF-κB signaling pathway, leading to down-regulation of pro-inflammatory cytokines releasing. In conclusion, our study suggested that carnosic acid nanoparticles protected against liver ischemia/reperfusion injury via its role of anti-oxidative, anti-apoptotic and anti-inflammatory bioactivity. PMID:27470360

  3. Modulation of neurotrophic signaling pathways by polyphenols

    PubMed Central

    Moosavi, Fatemeh; Hosseini, Razieh; Saso, Luciano; Firuzi, Omidreza

    2016-01-01

    Polyphenols are an important class of phytochemicals, and several lines of evidence have demonstrated their beneficial effects in the context of a number of pathologies including neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease. In this report, we review the studies on the effects of polyphenols on neuronal survival, growth, proliferation and differentiation, and the signaling pathways involved in these neurotrophic actions. Several polyphenols including flavonoids such as baicalein, daidzein, luteolin, and nobiletin as well as nonflavonoid polyphenols such as auraptene, carnosic acid, curcuminoids, and hydroxycinnamic acid derivatives including caffeic acid phentyl ester enhance neuronal survival and promote neurite outgrowth in vitro, a hallmark of neuronal differentiation. Assessment of underlying mechanisms, especially in PC12 neuronal-like cells, reveals that direct agonistic effect on tropomyosin receptor kinase (Trk) receptors, the main receptors of neurotrophic factors including nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) explains the action of few polyphenols such as 7,8-dihydroxyflavone. However, several other polyphenolic compounds activate extracellular signal-regulated kinase (ERK) and phosphoinositide 3-kinase (PI3K)/Akt pathways. Increased expression of neurotrophic factors in vitro and in vivo is the mechanism of neurotrophic action of flavonoids such as scutellarin, daidzein, genistein, and fisetin, while compounds like apigenin and ferulic acid increase cyclic adenosine monophosphate response element-binding protein (CREB) phosphorylation. Finally, the antioxidant activity of polyphenols reflected in the activation of Nrf2 pathway and the consequent upregulation of detoxification enzymes such as heme oxygenase-1 as well as the contribution of these effects to the neurotrophic activity have also been discussed. In conclusion, a better understanding of the neurotrophic effects of polyphenols and

  4. 2α-Hydroxyursolic Acid Inhibited Cell Proliferation and Induced Apoptosis in MDA-MB-231 Human Breast Cancer Cells through the p38/MAPK Signal Transduction Pathway.

    PubMed

    Jiang, Xue; Li, Tong; Liu, Rui Hai

    2016-03-01

    The mechanisms of action of 2α-hydroxyursolic acid in inhibiting cell proliferation and inducing apoptosis in MDA-MB-231 human breast cancer cells were investigated. The antiproliferative activity and cytotoxicity were determined by the methylene blue assay. The expression of proteins was determined using Western blot. 2α-Hydroxyursolic acid significantly inhibited MDA-MB-231 cell proliferation, and no cytotoxicity was observed at concentrations below 30 μM. 2α-Hydroxyursolic acid significantly down-regulated expressions of TRAF2, PCNA, cyclin D1, and CDK4 and up-regulated the expressions of p-ASK1, p-p38, p-p53, and p-21. 2α-Hydroxyursolic acid induced apoptosis in MDA-MB-231 cells by significantly increasing the Bax/Bcl-2 ratio and inducing the cleaved caspase-3. Additionally, treatment of SB203580, a p38 MAPK specific inhibitor, reversed the inhibition of PCNA, cyclin D1, and Bcl-2 expression induced by 2α-hydroxyursolic acid in MDA-MB-231 cells. These results suggested that 2α-hydroxyursolic acid exhibited anticancer activity through the inhibition of cell proliferation and the induction of apoptosis by regulating the p38/MAPK signal transduction pathway.

  5. Integration of ethylene and jasmonic acid signaling pathways in the expression of maize defense protein Mir1-CP.

    PubMed

    Ankala, A; Luthe, D S; Williams, W P; Wilkinson, J R

    2009-12-01

    In plants, ethylene and jasmonate control the defense responses to multiple stressors, including insect predation. Among the defense proteins known to be regulated by ethylene is maize insect resistance 1-cysteine protease (Mir1-CP). This protein is constitutively expressed in the insect-resistant maize (Zea mays) genotype Mp708; however, its abundance significantly increases during fall armyworm (Spodoptera frugiperda) herbivory. Within 1 h of herbivory by fall armyworm, Mir1-CP accumulates at the feeding site and continues to increase in abundance until 24 h without any increase in its transcript (mir1) levels. To resolve this discrepancy and elucidate the role of ethylene and jasmonate in the signaling of Mir1-CP expression, the effects of phytohormone biosynthesis and perception inhibitors on Mir1-CP expression were tested. Immunoblot analysis of Mir1-CP accumulation and quantitative reverse-transcriptase polymerase chain reaction examination of mir1 levels in these treated plants demonstrate that Mir1-CP accumulation is regulated by both transcript abundance and protein expression levels. The results also suggest that jasmonate functions upstream of ethylene in the Mir1-CP expression pathway, allowing for both low-level constitutive expression and a two-stage defensive response, an immediate response involving Mir1-CP accumulation and a delayed response inducing mir1 transcript expression.

  6. RNA Sequencing Identifies Upregulated Kyphoscoliosis Peptidase and Phosphatidic Acid Signaling Pathways in Muscle Hypertrophy Generated by Transgenic Expression of Myostatin Propeptide

    PubMed Central

    Miao, Yuanxin; Yang, Jinzeng; Xu, Zhong; Jing, Lu; Zhao, Shuhong; Li, Xinyun

    2015-01-01

    Myostatin (MSTN), a member of the transforming growth factor-β superfamily, plays a crucial negative role in muscle growth. MSTN mutations or inhibitions can dramatically increase muscle mass in most mammal species. Previously, we generated a transgenic mouse model of muscle hypertrophy via the transgenic expression of the MSTN N-terminal propeptide cDNA under the control of the skeletal muscle-specific MLC1 promoter. Here, we compare the mRNA profiles between transgenic mice and wild-type littermate controls with a high-throughput RNA sequencing method. The results show that 132 genes were significantly differentially expressed between transgenic mice and wild-type control mice; 97 of these genes were up-regulated, and 35 genes were down-regulated in the skeletal muscle. Several genes that had not been reported to be involved in muscle hypertrophy were identified, including up-regulated myosin binding protein H (mybph), and zinc metallopeptidase STE24 (Zmpste24). In addition, kyphoscoliosis peptidase (Ky), which plays a vital role in muscle growth, was also up-regulated in the transgenic mice. Interestingly, a pathway analysis based on grouping the differentially expressed genes uncovered that cardiomyopathy-related pathways and phosphatidic acid (PA) pathways (Dgki, Dgkz, Plcd4) were up-regulated. Increased PA signaling may increase mTOR signaling, resulting in skeletal muscle growth. The findings of the RNA sequencing analysis help to understand the molecular mechanisms of muscle hypertrophy caused by MSTN inhibition. PMID:25860951

  7. RNA sequencing identifies upregulated kyphoscoliosis peptidase and phosphatidic acid signaling pathways in muscle hypertrophy generated by transgenic expression of myostatin propeptide.

    PubMed

    Miao, Yuanxin; Yang, Jinzeng; Xu, Zhong; Jing, Lu; Zhao, Shuhong; Li, Xinyun

    2015-01-01

    Myostatin (MSTN), a member of the transforming growth factor-β superfamily, plays a crucial negative role in muscle growth. MSTN mutations or inhibitions can dramatically increase muscle mass in most mammal species. Previously, we generated a transgenic mouse model of muscle hypertrophy via the transgenic expression of the MSTN N-terminal propeptide cDNA under the control of the skeletal muscle-specific MLC1 promoter. Here, we compare the mRNA profiles between transgenic mice and wild-type littermate controls with a high-throughput RNA sequencing method. The results show that 132 genes were significantly differentially expressed between transgenic mice and wild-type control mice; 97 of these genes were up-regulated, and 35 genes were down-regulated in the skeletal muscle. Several genes that had not been reported to be involved in muscle hypertrophy were identified, including up-regulated myosin binding protein H (mybph), and zinc metallopeptidase STE24 (Zmpste24). In addition, kyphoscoliosis peptidase (Ky), which plays a vital role in muscle growth, was also up-regulated in the transgenic mice. Interestingly, a pathway analysis based on grouping the differentially expressed genes uncovered that cardiomyopathy-related pathways and phosphatidic acid (PA) pathways (Dgki, Dgkz, Plcd4) were up-regulated. Increased PA signaling may increase mTOR signaling, resulting in skeletal muscle growth. The findings of the RNA sequencing analysis help to understand the molecular mechanisms of muscle hypertrophy caused by MSTN inhibition. PMID:25860951

  8. RNA sequencing identifies upregulated kyphoscoliosis peptidase and phosphatidic acid signaling pathways in muscle hypertrophy generated by transgenic expression of myostatin propeptide.

    PubMed

    Miao, Yuanxin; Yang, Jinzeng; Xu, Zhong; Jing, Lu; Zhao, Shuhong; Li, Xinyun

    2015-04-09

    Myostatin (MSTN), a member of the transforming growth factor-β superfamily, plays a crucial negative role in muscle growth. MSTN mutations or inhibitions can dramatically increase muscle mass in most mammal species. Previously, we generated a transgenic mouse model of muscle hypertrophy via the transgenic expression of the MSTN N-terminal propeptide cDNA under the control of the skeletal muscle-specific MLC1 promoter. Here, we compare the mRNA profiles between transgenic mice and wild-type littermate controls with a high-throughput RNA sequencing method. The results show that 132 genes were significantly differentially expressed between transgenic mice and wild-type control mice; 97 of these genes were up-regulated, and 35 genes were down-regulated in the skeletal muscle. Several genes that had not been reported to be involved in muscle hypertrophy were identified, including up-regulated myosin binding protein H (mybph), and zinc metallopeptidase STE24 (Zmpste24). In addition, kyphoscoliosis peptidase (Ky), which plays a vital role in muscle growth, was also up-regulated in the transgenic mice. Interestingly, a pathway analysis based on grouping the differentially expressed genes uncovered that cardiomyopathy-related pathways and phosphatidic acid (PA) pathways (Dgki, Dgkz, Plcd4) were up-regulated. Increased PA signaling may increase mTOR signaling, resulting in skeletal muscle growth. The findings of the RNA sequencing analysis help to understand the molecular mechanisms of muscle hypertrophy caused by MSTN inhibition.

  9. Redox Signaling and CBF-Responsive Pathway Are Involved in Salicylic Acid-Improved Photosynthesis and Growth under Chilling Stress in Watermelon

    PubMed Central

    Cheng, Fei; Lu, Junyang; Gao, Min; Shi, Kai; Kong, Qiusheng; Huang, Yuan; Bie, Zhilong

    2016-01-01

    Salicylic acid (SA) plays an important role in plant response to abiotic stresses. This study investigated the potential role of SA in alleviating the adverse effects of chilling stress on photosynthesis and growth in watermelon (Citrullus lanatus). Chilling stress induced the simultaneous accumulation of free and conjugated SA in watermelon plants, and the chilling-induced SA production was attributed to the phenylalanine ammonia-lyase pathway. Applying SA at moderate concentrations induced chilling tolerance, whereas inhibition of SA biosynthesis by L-α-aminooxy-β-phenylpropionic acid (AOPP) increased the photooxidation of PS II under chilling stress in watermelon, resulting in reduced photosynthesis and growth. Chilling induced a transient increase in the ratios of reduced to oxidized glutathione and reduced ascorbate to dehydroascorbate. Then, the expression of antioxidant genes was upregulated, and the activities of antioxidant enzymes were enhanced. Furthermore, SA-induced chilling tolerance was associated with cellular glutathione and ascorbate homeostasis, which served as redox signals to regulate antioxidant metabolism under chilling stress. AOPP treatment stimulated the chilling-induced expression of cold-responsive genes, particularly via C-repeat binding factors CBF3 and CBF4. These results confirm the synergistic role of SA signaling and the CBF-dependent responsive pathway during chilling stress in watermelon. PMID:27777580

  10. Propolis cinnamic acid derivatives induce apoptosis through both extrinsic and intrinsic apoptosis signaling pathways and modulate of miRNA expression.

    PubMed

    Kumazaki, Minami; Shinohara, Haruka; Taniguchi, Kohei; Yamada, Nami; Ohta, Shozo; Ichihara, Kenji; Akao, Yukihiro

    2014-01-01

    Propolis cinnamic acid derivatives have a number of biological activities including anti-oxidant and anti-cancer ones. In this study, we aimed to elucidate the mechanism of the anti-cancer activity of 3 representative propolis cinnamic acid derivatives, i.e., Artepilin C, Baccharin and Drupanin in human colon cancer cell lines. Our study demonstrated that these compounds had a potent apoptosis-inductive effect even on drug-resistant colon cancer cells. Combination treatment of human colon cancer DLD-1 cells with 2 of these compounds, each at its IC20 concentration, induced apoptosis by stimulating both intrinsic and extrinsic apoptosis signaling pathways. Especially, Baccharin plus Drupanin exhibited a synergistic growth-inhibitory effect by strengthening both intrinsic and extrinsic apoptotic signaling transduction through TRAIL/DR4/5 and/or FasL/Fas death-signaling loops and by increasing the expression level of miR-143, resulting in decreased expression levels of the target gene MAPK/Erk5 and its downstream target c-Myc. These data suggest that the supplemental intake of these compounds found in propolis has enormous significance with respect to cancer prevention.

  11. A splice donor mutation in NAA10 results in the dysregulation of the retinoic acid signaling pathway and causes Lenz microphthalmia syndrome

    PubMed Central

    Esmailpour, Taraneh; Riazifar, Hamidreza; Liu, Linan; Donkervoort, Sandra; Huang, Vincent H; Madaan, Shreshtha; Shoucri, Bassem M; Busch, Anke; Wu, Jie; Towbin, Alexander; Chadwick, Robert B; Sequeira, Adolfo; Vawter, Marquis P; Sun, Guoli; Johnston, Jennifer J; Biesecker, Leslie G; Kawaguchi, Riki; Sun, Hui; Kimonis, Virginia; Huang, Taosheng

    2014-01-01

    Introduction Lenz microphthalmia syndrome (LMS) is a genetically heterogeneous X-linked disorder characterised by microphthalmia/anophthalmia, skeletal abnormalities, genitourinary malformations, and anomalies of the digits, ears, and teeth. Intellectual disability and seizure disorders are seen in about 60% of affected males. To date, no gene has been identified for LMS in the microphthalmia syndrome 1 locus (MCOPS1). In this study, we aim to find the disease-causing gene for this condition. Methods and results Using exome sequencing in a family with three affected brothers, we identified a mutation in the intron 7 splice donor site (c.471+2T→A) of the N-acetyltransferase NAA10 gene. NAA10 has been previously shown to be mutated in patients with Ogden syndrome, which is clinically distinct from LMS. Linkage studies for this family mapped the disease locus to Xq27-Xq28, which was consistent with the locus of NAA10. The mutation co-segregated with the phenotype and cDNA analysis showed aberrant transcripts. Patient fibroblasts lacked expression of full length NAA10 protein and displayed cell proliferation defects. Expression array studies showed significant dysregulation of genes associated with genetic forms of anophthalmia such as BMP4, STRA6, and downstream targets of BCOR and the canonical WNT pathway. In particular, STRA6 is a retinol binding protein receptor that mediates cellular uptake of retinol/vitamin A and plays a major role in regulating the retinoic acid signalling pathway. A retinol uptake assay showed that retinol uptake was decreased in patient cells. Conclusions We conclude that the NAA10 mutation is the cause of LMS in this family, likely through the dysregulation of the retinoic acid signalling pathway. PMID:24431331

  12. The poly-γ-d-glutamic acid capsule surrogate of the Bacillus anthracis capsule induces nitric oxide production via the platelet activating factor receptor signaling pathway.

    PubMed

    Lee, Hae-Ri; Jeon, Jun Ho; Park, Ok-Kyu; Chun, Jeong-Hoon; Park, Jungchan; Rhie, Gi-Eun

    2015-12-01

    The poly-γ-d-glutamic acid (PGA) capsule, a major virulence factor of Bacillus anthracis, confers protection of the bacillus from phagocytosis and allows its unimpeded growth in the host. PGA capsules released from B. anthracis are associated with lethal toxin in the blood of experimentally infected animals and enhance the cytotoxic effect of lethal toxin on macrophages. In addition, PGA capsule itself activates macrophages and dendritic cells to produce proinflammatory cytokine such as IL-1β, indicating multiple roles of PGA capsule in anthrax pathogenesis. Here we report that PGA capsule of Bacillus licheniformis, a surrogate of B. anthracis capsule, induces production of nitric oxide (NO) in RAW264.7 cells and bone marrow-derived macrophages. NO production was induced by PGA in a dose-dependent manner and was markedly reduced by inhibitors of inducible NO synthase (iNOS), suggesting iNOS-dependent production of NO. Induction of NO production by PGA was not observed in macrophages from TLR2-deficient mice and was also substantially inhibited in RAW264.7 cells by pretreatment of TLR2 blocking antibody. Subsequently, the downstream signaling events such as ERK, JNK and p38 of MAPK pathways as well as NF-κB activation were required for PGA-induced NO production. In addition, the induced NO production was significantly suppressed by treatment with antagonists of platelet activating factor receptor (PAFR) or PAFR siRNA, and mediated through PAFR/Jak2/STAT-1 signaling pathway. These findings suggest that PGA capsule induces NO production in macrophages by triggering both TLR2 and PAFR signaling pathways which lead to activation of NF-kB and STAT-1, respectively.

  13. All-trans retinoic acid prevents epidural fibrosis through NF-κB signaling pathway in post-laminectomy rats.

    PubMed

    Zhang, Chao; Kong, Xiaohong; Ning, Guangzhi; Liang, Zhipin; Qu, Tongjun; Chen, Feiran; Cao, Daigui; Wang, Tianyi; Sharma, Hari S; Feng, Shiqing

    2014-04-01

    Laminectomy is a widely accepted treatment for lumbar disorders, and epidural fibrosis (EF) is a common complication. EF is thought to cause post-operative pain recurrence after laminectomy or discectomy. All-trans retinoic acid (ATRA) has shown anti-fibrotic, anti-inflammatory, and anti-proliferative functions. The object of this study was to investigate the effects of ATRA on the prevention of EF in post-laminectomy rats. In vitro, the anti-fibrotic effect of ATRA was demonstrated with cultured fibroblasts count, which comprised of those that were cultured with/without ATRA. In vivo, rats underwent laminectomy at the L1-L2 levels. We first demonstrated the beneficial effects using 0.05% ATRA compared to vehicle (control group). We found that a higher concentration of ATRA (0.1%) achieved dose-dependent results. Hydroxyproline content, Rydell score, vimentin-positive cell density, fibroblast density, inflammatory cell density and inflammatory factor expression levels all suggested better outcomes in the 0.1% ATRA rats compared to the other three groups. Presumably, these effects involved ATRA's ability to suppress transforming growth factor (TGF-β1) and interleukin (IL)-6 which was confirmed with reverse-transcriptase polymerase chain reaction (RT-PCR). Finally we demonstrated that ATRA down-regulated nuclear factor (NF)-κB by immunohistochemistry and western blotting for p65 and inhibition of κB (IκBα), respectively. Our findings indicate that topical application of ATRA can inhibit fibroblast proliferation, decrease TGF-β1 and IL-6 expression level, and prevent epidural scar adhesion in rats. The highest concentration employed in this study (0.1%) was the most effective. ATRA suppressed EF through down-regulating NF-κB signaling, whose specific mechanism is suppression of IκB phosphorylation and proteolytic degradation.

  14. Down-regulation of the tumor suppressor gene retinoic acid receptor beta2 through the phosphoinositide 3-kinase/Akt signaling pathway.

    PubMed

    Lefebvre, Bruno; Brand, Céline; Flajollet, Sébastien; Lefebvre, Philippe

    2006-09-01

    The retinoic acid receptor beta2 (RARbeta2) is a potent, retinoid-inducible tumor suppressor gene, which is a critical molecular relay for retinoid actions in cells. Its down-regulation, or loss of expression, leads to resistance of cancer cells to retinoid treatment. Up to now, no primary mechanism underlying the repression of the RARbeta2 gene expression, hence affecting cellular retinoid sensitivity, has been identified. Here, we demonstrate that the phosphoinositide 3-kinase/Akt signaling pathway affects cellular retinoid sensitivity, by regulating corepressor recruitment to the RARbeta2 promoter. Through direct phosphorylation of the corepressor silencing mediator for retinoic and thyroid hormone receptors (SMRT), Akt stabilized RAR/SMRT interaction, leading to an increased tethering of SMRT to the RARbeta2 promoter, decreased histone acetylation, down-regulation of the RARbeta2 expression, and impaired cellular differentiation in response to retinoid. The phosphoinositide 3-kinase/Akt signaling pathway, an important modulator of cellular survival, has thus a direct impact on cellular retinoid sensitivity, and its deregulation may be the triggering event in retinoid resistance of cancer cells.

  15. Shared Segment Analysis and Next-Generation Sequencing Implicates the Retinoic Acid Signaling Pathway in Total Anomalous Pulmonary Venous Return (TAPVR)

    PubMed Central

    Nash, Dustin; Arrington, Cammon B.; Kennedy, Brett J.; Yandell, Mark; Wu, Wilfred; Zhang, Wenying; Ware, Stephanie; Jorde, Lynn B.; Gruber, Peter J.; Yost, H. Joseph

    2015-01-01

    Most isolated congenital heart defects are thought to be sporadic and are often ascribed to multifactorial mechanisms with poorly understood genetics. Total Anomalous Pulmonary Venous Return (TAPVR) occurs in 1 in 15,000 live-born infants and occurs either in isolation or as part of a syndrome involving aberrant left-right development. Previously, we reported causative links between TAVPR and the PDGFRA gene. TAPVR has also been linked to the ANKRD1/CARP genes. However, these genes only explain a small fraction of the heritability of the condition. By examination of phased single nucleotide polymorphism genotype data from 5 distantly related TAPVR patients we identified a single 25 cM shared, Identical by Descent genomic segment on the short arm of chromosome 12 shared by 3 of the patients and their obligate-carrier parents. Whole genome sequence (WGS) analysis identified a non-synonymous variant within the shared segment in the retinol binding protein 5 (RBP5) gene. The RBP5 variant is predicted to be deleterious and is overrepresented in the TAPVR population. Gene expression and functional analysis of the zebrafish orthologue, rbp7, supports the notion that RBP5 is a TAPVR susceptibility gene. Additional sequence analysis also uncovered deleterious variants in genes associated with retinoic acid signaling, including NODAL and retinol dehydrogenase 10. These data indicate that genetic variation in the retinoic acid signaling pathway confers, in part, susceptibility to TAPVR. PMID:26121141

  16. Alpha-2-glycoprotein 1(AZGP1) regulates biological behaviors of LoVo cells by down-regulating mTOR signaling pathway and endogenous fatty acid synthesis.

    PubMed

    Chang, Ligong; Tian, Xiaoqiang; Lu, Yinghui; Jia, Min; Wu, Peng; Huang, Peilin

    2014-01-01

    AZGP1 is a multifaceted protein associated with lipid mobilization, a process that is regulated by FASN and other metabolic pathways such as mTOR signaling. The active mTOR signaling pathway has been found to be involved in a variety of tumors. However, it remains unclear whether it is involved in the regulation of AZGP1 and FASN. An AZGP1-expressing plasmid was transfected into a human colorectal cancer cell line (LoVo) with a low expression of AZGP1. The expression of AZGP1, FASN, eIF4E, p-mTOR, p-S6,and S6K1 were measured by Western blot analysis, and target genes were detected by RT-PCR. Cell proliferation was studied using the MTT and colony formation assays. The analysis of apoptosis and the cell cycle phase were assessed by flow cytometry. The capacity of cell migration was investigated using the transwell migration assay. We found that the expression of AZGP1 was up-regulated while the expression of FASN, eIF4E, p-mTOR, p-S6, and S6K1 were down-regulated in LoVo cells after AZGP1 was expressed. The proliferation of malignant cells was reduced in AZGP1-overexpression cells, which is consistent with an increased in the G2-arrest and apoptosis rate. Furthermore, the migration of AZGP1-overexpression cells was decreased. The overexpression of AZGP1 suppressed the activation of the mTOR pathway and endogenous FASN-regulated fatty acid synthesis, mitigating the malignant phenotype of LoVo cells. Herein, we provide evidence that AZGP1 may constitute a novel tumor suppressor for LoVo colorectal cancer cells.

  17. Blocking TGF-β Signaling Pathway Preserves Mitochondrial Proteostasis and Reduces Early Activation of PDGFRβ+ Pericytes in Aristolochic Acid Induced Acute Kidney Injury in Wistar Male Rats

    PubMed Central

    Pozdzik, Agnieszka A.; Giordano, Laetitia; Li, Gang; Antoine, Marie-Hélène; Quellard, Nathalie; Godet, Julie; De Prez, Eric; Husson, Cécile; Declèves, Anne-Emilie; Arlt, Volker M.; Goujon, Jean-Michel; Brochériou-Spelle, Isabelle; Ledbetter, Steven R.; Caron, Nathalie; Nortier, Joëlle L.

    2016-01-01

    Background The platelet-derived growth factor receptor β (PDGFRβ)+ perivascular cell activation becomes increasingly recognized as a main source of scar-associated kidney myofibroblasts and recently emerged as a new cellular therapeutic target. Aims In this regard, we first confirmed the presence of PDGFRβ+ perivascular cells in a human case of end-stage aristolochic acid nephropathy (AAN) and thereafter we focused on the early fibrosis events of transforming growth factor β (TGFβ) inhibition in a rat model of AAN. Materials and Methods Neutralizing anti-TGFβ antibody (1D11) and its control isotype (13C4) were administered (5 mg/kg, i.p.) at Days -1, 0, 2 and 4; AA (15 mg/kg, sc) was injected daily. Results At Day 5, 1D11 significantly suppressed p-Smad2/3 signaling pathway improving renal function impairment, reduced the score of acute tubular necrosis, peritubular capillaritis, interstitial inflammation and neoangiogenesis. 1D11 markedly decreased interstitial edema, disruption of tubular basement membrane loss of brush border, cytoplasmic edema and organelle ultrastructure alterations (mitochondrial disruption and endoplasmic reticulum edema) in proximal tubular epithelial cells. Moreover, 1D11 significantly inhibited p-PERK activation and attenuated dysregulation of unfolded protein response (UPR) pathways, endoplasmic reticulum and mitochondrial proteostasis in vivo and in vitro. Conclusions The early inhibition of p-Smad2/3 signaling pathway improved acute renal function impairment, partially prevented epithelial-endothelial axis activation by maintaining PTEC proteostasis and reduced early PDGFRβ+ pericytes-derived myofibroblasts accumulation. PMID:27379382

  18. All-Trans Retinoic Acid Inhibits Human Colorectal Cancer Cells RKO Migration via Downregulating Myosin Light Chain Kinase Expression through MAPK Signaling Pathway.

    PubMed

    Zuo, Li; Yang, Xiaoping; Lu, Man; Hu, Ruolei; Zhu, Huaqing; Zhang, Sumei; Zhou, Qing; Chen, Feihu; Gui, Shuyu; Wang, Yuan

    2016-10-01

    All-trans-retinoic acid (ATRA) inhibits the invasive and metastatic potentials of various cancer cells. However, the underlying mechanism is unclear. Here, we demonstrate that ATRA inhibited colorectal cancer cells RKO (human colon adenocarcinoma cell) migration by downregulating cell movement and increasing cell adhesion. ATRA inhibited the expression and activation of myosin light chain kinase (MLCK) in RKO cells, while the expression level of MLC phosphatase (MLCP) had no change in RKO cells treated with or without ATRA. The expression and activity of MLC was also inhibited in RKO cells exposed to ATRA. Intriguingly, ATRA increased the expression of occludin messenger RNA (mRNA) and protein and its localization on cell membrane. However, ATRA did not change the expression of zonula occludens 1 (ZO-1), but increased the accumulation of ZO-1 on RKO cells membrane. ML-7, an inhibitor of MLCK, significantly inhibited RKO cell migration. Furthermore, knockdown of endogenous MLCK expression inhibited RKO migration. Mechanistically, we showed that MAPK-specific inhibitor PD98059 enhanced the inhibitory effect of ATRA on RKO migration. In contrast, phorbol 12-myristate 13-acetate (PMA) attenuated the effects of ATRA in RKO cells. Moreover, knocking down endogenous extracellular signal-regulated kinase (ERK) expression inhibited MLCK expression in the RKO cells. In conclusion, ATRA inhibits RKO migration by reducing MLCK expression via extracellular signal-regulated kinase 1/Mitogen-activated protein kinase (ERK1/MAPK) signaling pathway. PMID:27564600

  19. The Transcription Factor p8 Regulates Autophagy in Response to Palmitic Acid Stress via a Mammalian Target of Rapamycin (mTOR)-independent Signaling Pathway.

    PubMed

    Jia, Sheng-Nan; Lin, Cheng; Chen, Dian-Fu; Li, An-Qi; Dai, Li; Zhang, Li; Zhao, Ling-Ling; Yang, Jin-Shu; Yang, Fan; Yang, Wei-Jun

    2016-02-26

    Autophagy is an evolutionarily conserved degradative process that allows cells to maintain homoeostasis in numerous physiological situations. This process also functions as an essential protective response to endoplasmic reticulum (ER) stress, which promotes the removal and degradation of unfolded proteins. However, little is known regarding the mechanism by which autophagy is initiated and regulated in response to ER stress. In this study, different types of autophagy were identified in human gastric cancer MKN45 cells in response to the stress induced by nutrient starvation or lipotoxicity in which the regulation of these pathways is mammalian target of rapamycin (mTOR)-dependent or -independent, respectively. Interestingly, we found that p8, a stress-inducible transcription factor, was enhanced in MKN45 cells treated with palmitic acid to induce lipotoxicity. Furthermore, an increase in autophagy was observed in MKN45 cells stably overexpressing p8 using a lentivirus system, and autophagy induced by palmitic acid was blocked by p8 RNAi compared with the control. Western blotting analyses showed that autophagy was regulated by p8 or mTOR in response to the protein kinase-like endoplasmic reticulum kinase/activating transcription factor 6-mediated ER stress of lipotoxicity or the parkin-mediated mitochondrial stress of nutrient starvation, respectively. Furthermore, our results indicated that autophagy induced by palmitic acid is mTOR-independent, but this autophagy pathway was regulated by p8 via p53- and PKCα-mediated signaling in MKN45 cells. Our findings provide insights into the role of p8 in regulating autophagy induced by the lipotoxic effects of excess fat accumulation in cells. PMID:26733200

  20. 18α-Glycyrrhetinic Acid Induces Apoptosis of HL-60 Human Leukemia Cells through Caspases- and Mitochondria-Dependent Signaling Pathways.

    PubMed

    Huang, Yi-Chang; Kuo, Chao-Lin; Lu, Kung-Wen; Lin, Jen-Jyh; Yang, Jiun-Long; Wu, Rick Sai-Chuen; Wu, Ping-Ping; Chung, Jing-Gung

    2016-01-01

    In this study we investigate the molecular mechanisms of caspases and mitochondria in the extrinsic and intrinsic signal apoptosis pathways in human leukemia HL-60 cells after in vitro exposure to 18α-glycyrrhetinic acid (18α-GA). Cells were exposed to 18α-GA at various concentrations for various time periods and were harvested for flow cytometry total viable cell and apoptotic cell death measurements. Cells treated with 18α-GA significantly inhibited cell proliferation and induced cell apoptosis in a dose-dependent manner, with an IC50 value of 100 μM at 48 h. The cell growth inhibition resulted in induction of apoptosis and decreased the mitochondria membrane potential (ΔΨm) and increased caspase-8, -9 and -3 activities. Furthermore, cytochrome c and AIF were released from mitochondria, as shown by western blotting and confirmed by confocal laser microscopy. Western blotting showed that 18α-GA increased the levels of pro-apoptotic proteins such as Bax and Bid and decreased the anti-apoptotic proteins such as Bcl-2 and Bcl-xl, furthermore, results also showed that 18α-GA increased Fas and Fas-L which are associated with surface death receptor in HL-60 cells. Based on those observations, the present study supports the hypothesis that 18α-GA-induced apoptosis in HL-60 cells involves the activation of the both extrinsic and intrinsic apoptotic pathways. PMID:27376261

  1. G-protein-coupled receptor cell signaling pathways mediating embryonic chick retinal growth cone collapse induced by lysophosphatidic acid and sphingosine-1-phosphate.

    PubMed

    Fincher, Jarod; Whiteneck, Canaan; Birgbauer, Eric

    2014-01-01

    In the development of the nervous system, one of the critical aspects is the proper navigation of axons to their targets, i.e. the problem of axonal guidance. We used the chick visual system as a model to investigate the role of the lysophospholipids lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) as potential axon guidance cues. We showed that both LPA and S1P cause a specific, dose-dependent growth cone collapse of retinal neurons in vitro in the chick model system, with slight differences compared to the mouse but very similar to observations in Xenopus. Because LPA and S1P receptors are G-protein-coupled receptors, we analyzed the intracellular signaling pathways using pharmacological inhibitors in chick retinal neurons. Blocking rho kinase (ROCK) prevented growth cone collapse by LPA and S1P, while blocking PLC or chelating calcium had no effect on growth cone collapse. Inhibition of Gi/o with pertussis toxin resulted in a partial reduction of growth cone collapse, both with LPA and with S1P. Inhibition of p38 blocked growth cone collapse mediated by LPA but not S1P. Thus, in addition to the involvement of the G12/13-ROCK pathway, LPA- and S1P-induced collapse of chick retinal growth cones has a partial requirement for Gi/o. PMID:25138637

  2. α-Lipoic Acids Promote the Protein Synthesis of C2C12 Myotubes by the TLR2/PI3K Signaling Pathway.

    PubMed

    Jing, Yuanyuan; Cai, Xingcai; Xu, Yaqiong; Zhu, Canjun; Wang, Lina; Wang, Songbo; Zhu, Xiaotong; Gao, Ping; Zhang, Yongliang; Jiang, Qingyan; Shu, Gang

    2016-03-01

    Skeletal muscle protein turnover is regulated by endocrine hormones, nutrients, and inflammation. α-Lipoic acid (ALA) plays an important role in energy homeostasis. Therefore, the aim of this study was to investigate the effects of ALA on protein synthesis in skeletal muscles and reveal the underlying mechanism. ALA (25 μM) significantly increased the protein synthesis and phosphorylation of Akt, mTOR, and S6 in C2C12 myotubes with attenuated phosphorylation of AMPK, Ikkα/β, and eIF2α. Intraperitoneal injection of 50 mg/kg ALA also produced the same results in mouse gastrocnemius. Both the PI3K (LY294002) and mTOR (rapamycin) inhibitors abolished the effects of ALA on protein synthesis in the C2C12 myotubes. However, AICAR (AMPK agonist) failed to block the activation of mTOR and S6 by ALA. ALA increased TLR2 and MyD88 mRNA expression in the C2C12 myotubes. TLR2 knockdown by siRNA almost eliminated the effects of ALA on protein synthesis and the Akt/mTOR pathway in the C2C12 myotubes. Immunoprecipitation data showed that ALA enhanced the p85 subunit of PI3K binding to MyD88. These findings indicate that ALA induces protein synthesis and the PI3K/Akt signaling pathway by TLR2.

  3. Mycosporine-Like Amino Acids Promote Wound Healing through Focal Adhesion Kinase (FAK) and Mitogen-Activated Protein Kinases (MAP Kinases) Signaling Pathway in Keratinocytes.

    PubMed

    Choi, Yun-Hee; Yang, Dong Joo; Kulkarni, Atul; Moh, Sang Hyun; Kim, Ki Woo

    2015-11-26

    Mycosporine-like amino acids (MAAs) are secondary metabolites found in diverse marine, freshwater, and terrestrial organisms. Evidence suggests that MAAs have several beneficial effects on skin homeostasis such as protection against UV radiation and reactive oxygen species (ROS). In addition, MAAs are also involved in the modulation of skin fibroblasts proliferation. However, the regulatory function of MAAs on wound repair in human skin is not yet clearly elucidated. To investigate the roles of MAAs on the wound healing process in human keratinocytes, three MAAs, Shinorine (SH), Mycosporine-glycine (M-Gly), and Porphyra (P334) were purified from Chlamydomonas hedlyei and Porphyra yezoensis. We found that SH, M-Gly, and P334 have significant effects on the wound healing process in human keratinocytes and these effects were mediated by activation of focal adhesion kinases (FAK), extracellular signal-regulated kinases (ERK), and c-Jun N-terminal kinases (JNK). These results suggest that MAAs accelerate wound repair by activating the FAK-MAPK signaling pathways. This study also indicates that MAAs can act as a new wound healing agent and further suggests that MAAs might be a novel biomaterial for wound healing therapies.

  4. Inhibition of MAPK signaling pathways enhances cell death induced by 5-Aminolevulinic acid-photodynamic therapy in skin squamous carcinoma cells.

    PubMed

    Ge, Xinhong; Liu, Jianping; Shi, Zhiyun; Jing, Li; Yu, Nan; Zhang, Xiujuan; Jiao, Yaning; Wang, Yili; Li, P Andy

    2016-04-01

    Combination of a photosensitizer, 5-aminolevulinic acid (ALA), with photodynamic therapy (PDT) has been widely used to treat skin squamous cell carcinoma (SCC). However, a portion of SCC patients do not respond well to PDT. The molecular reason for this resistance is not clear. We hypothesize that mitogen-activated phosphorylation kinase (MAPK) plays a key role in mediating SCC resistance to PDT. To determine whether inhibition of MAPK signaling enhances the anti-tumor effect of ALA-PDT in SCC. The human squamous carcinoma cell line, SCL-1, was either untreated or treated with various combinations of ALA, PDT light source and inhibitors of MAPK signaling components. ALA-PDT treatment significantly decreased cell viability, increased the percentage of annexin-V positive cells and resulted in formation of apoptotic bodies. ALA-PDT treated cells showed increased levels of p-MEK, p-ERK1/2, p-p38, p-Elk-1, p-JNK and p-c-Jun. Addition of inhibitors for ERK1/2 (PD98059), p38 (SB203580) and JNK (SP60125) reversed the changes and led to a more dramatic decrease in SCL-1 cell viability than seen with ALA-PDT alone. Inhibition of the MAPK pathway enhances the cytotoxic effect of ALA-PDT on SCL-1.

  5. Involvement of mitogen-activated protein kinase and NF-κB signaling pathways in perfluorooctane sulfonic acid-induced inflammatory reaction in BV2 microglial cells.

    PubMed

    Zhu, Jingying; Qian, Wenyi; Wang, Yixin; Gao, Rong; Wang, Jun; Xiao, Hang

    2015-12-01

    Microglial activation is closely related to the pathogenesis of neurodegenerative diseases by producing proinflammatory cytokines. Perfluorooctane sulfonic acid (PFOS), known as an emerging persistent organic pollutant, is reported to disturb human immune homeostasis; however, whether it affects cytokine production or the immune response in the central nervous system remains unclear. The present study was aimed to explore whether PFOS contributed to inflammatory action and to investigate the corresponding mechanisms in BV2 microglia. PFOS-mediated morphologic changes, cytokine responses and signaling events were examined by light microscopy, real-time polymerase chain reaction, enzyme-linked immunosorbent assay and Western blot assays. Our results indicated that PFOS increased BV2 cells activation and simultaneously increased tumor necrosis factor alpha and interleukin-6 expression. In addition, the c-Jun N-terminal protein kinase inhibitor (SP600125), as well as ERK1/2 blocker (PD98059), transcriptionally at least, displayed anti-inflammatory properties on PFOS-elicited cytokine responses. Moreover, the inflammatory transcription factor NF-κB was specifically activated by PFOS as well. These results, taken together, suggested that PFOS exerts its functional effects on the response of microglial cell activation via, in part, the c-Jun N-terminal protein kinase, ERK and NF-κB signaling pathways with its subsequent influence on proinflammatory action.

  6. Mycosporine-Like Amino Acids Promote Wound Healing through Focal Adhesion Kinase (FAK) and Mitogen-Activated Protein Kinases (MAP Kinases) Signaling Pathway in Keratinocytes

    PubMed Central

    Choi, Yun-Hee; Yang, Dong Joo; Kulkarni, Atul; Moh, Sang Hyun; Kim, Ki Woo

    2015-01-01

    Mycosporine-like amino acids (MAAs) are secondary metabolites found in diverse marine, freshwater, and terrestrial organisms. Evidence suggests that MAAs have several beneficial effects on skin homeostasis such as protection against UV radiation and reactive oxygen species (ROS). In addition, MAAs are also involved in the modulation of skin fibroblasts proliferation. However, the regulatory function of MAAs on wound repair in human skin is not yet clearly elucidated. To investigate the roles of MAAs on the wound healing process in human keratinocytes, three MAAs, Shinorine (SH), Mycosporine-glycine (M-Gly), and Porphyra (P334) were purified from Chlamydomonas hedlyei and Porphyra yezoensis. We found that SH, M-Gly, and P334 have significant effects on the wound healing process in human keratinocytes and these effects were mediated by activation of focal adhesion kinases (FAK), extracellular signal-regulated kinases (ERK), and c-Jun N-terminal kinases (JNK). These results suggest that MAAs accelerate wound repair by activating the FAK-MAPK signaling pathways. This study also indicates that MAAs can act as a new wound healing agent and further suggests that MAAs might be a novel biomaterial for wound healing therapies. PMID:26703626

  7. Inhibition of MAPK signaling pathways enhances cell death induced by 5-Aminolevulinic acid-photodynamic therapy in skin squamous carcinoma cells.

    PubMed

    Ge, Xinhong; Liu, Jianping; Shi, Zhiyun; Jing, Li; Yu, Nan; Zhang, Xiujuan; Jiao, Yaning; Wang, Yili; Li, P Andy

    2016-04-01

    Combination of a photosensitizer, 5-aminolevulinic acid (ALA), with photodynamic therapy (PDT) has been widely used to treat skin squamous cell carcinoma (SCC). However, a portion of SCC patients do not respond well to PDT. The molecular reason for this resistance is not clear. We hypothesize that mitogen-activated phosphorylation kinase (MAPK) plays a key role in mediating SCC resistance to PDT. To determine whether inhibition of MAPK signaling enhances the anti-tumor effect of ALA-PDT in SCC. The human squamous carcinoma cell line, SCL-1, was either untreated or treated with various combinations of ALA, PDT light source and inhibitors of MAPK signaling components. ALA-PDT treatment significantly decreased cell viability, increased the percentage of annexin-V positive cells and resulted in formation of apoptotic bodies. ALA-PDT treated cells showed increased levels of p-MEK, p-ERK1/2, p-p38, p-Elk-1, p-JNK and p-c-Jun. Addition of inhibitors for ERK1/2 (PD98059), p38 (SB203580) and JNK (SP60125) reversed the changes and led to a more dramatic decrease in SCL-1 cell viability than seen with ALA-PDT alone. Inhibition of the MAPK pathway enhances the cytotoxic effect of ALA-PDT on SCL-1. PMID:27032574

  8. α-Lipoic acid up-regulates expression of peroxisome proliferator-activated receptor β in skeletal muscle: involvement of the JNK signaling pathway.

    PubMed

    Rousseau, Anne-Sophie; Sibille, Brigitte; Murdaca, Joseph; Mothe-Satney, Isabelle; Grimaldi, Paul A; Neels, Jaap G

    2016-03-01

    We hypothesized that α-lipoic acid (α-LA) might interact with the transcriptional control of peroxisome proliferator-activated receptor (PPAR)β in skeletal muscle. Molecular mechanisms were investigated using differentiated C2C12 myotubes treated with α-LA and/or PPARβ agonist GW0742. In vivo studies with 3-mo-old C57Bl6 mice were realized: voluntary wheel running (VWR) training (7 wk), and a 6 wk diet containing (or not) α-LA (0.25% wt/wt). This last condition was combined with (or not) 1 bout of treadmill exercise (18 m/min for 1 h). Using a reporter assay, we demonstrate that α-LA is not an agonist of PPARβ but regulates PPARβ target gene expression through an active PPARβ pathway. GW0742-induced pyruvate dehydrogenase kinase 4 mRNA is potentiated by α-LA. In C2C12, α-LA lowers the activation of the JNK signaling pathway and increases PPARβ mRNA and protein levels (2-fold) to the same extent as with the JNK inhibitor SP600125. Similarly to VWR training effect, PPARβ expression increases (2-fold) in vastus lateralis of animals fed an α-LA-enriched diet. However, α-LA treatment does not further stimulate the adaptive up-regulation of PPARβ observed in response to 1 bout of exercise. We have identified a novel mechanism of regulation of PPARβ expression/action in skeletal muscle with potential physiologic application through the action of α-LA, involving the JNK pathway.

  9. The Apoptotic Effect of Ursolic Acid on SK-Hep-1 Cells is Regulated by the PI3K/Akt, p38 and JNK MAPK Signaling Pathways.

    PubMed

    Chuang, Wan-Ling; Lin, Ping-Yi; Lin, Hui-Chuan; Chen, Yao-Li

    2016-01-01

    Ursolic acid (UA) is a pentacyclic triterpene acid that is present in a wide variety of medicinal herbs and edible plants. This study investigated the effect of UA on apoptosis and proliferation of hepatocellular carcinoma SK-Hep-1 cells. After treatment of SK-Hep-1 cells with different concentrations of UA, we observed that cell viability was reduced in a dose- and time-dependent manner. Furthermore, there was a dose-dependent increase in the percentage of cells in the sub-G1 and G2/M phases, with cells treated with 60 μM showing the highest percentages of cells in those phases. UA-induced chromatin condensation of nuclei was observed by using DAPI staining. The western blot results revealed that exposure to UA was associated with decreased expression of the anti-apoptotic proteins Mcl-1, Bcl-xL, Bcl-2, and TCTP and increased expression of apoptosis-related proteins TNF-α, Fas, FADD, Bax, cleaved caspase-3, caspase-8, caspase-9, and PARP. Immunocytochemistry staining showed that treatment with UA resulted in increased expression of caspase-3. Moreover, exposure to UA resulted in the inhibition of the PI3K/Akt and p38 MAPK signaling pathways. These findings suggest that UA inhibits the proliferation of SK-Hep-1 cells and induces apoptosis.

  10. Leptin signalling pathways in hypothalamic neurons.

    PubMed

    Kwon, Obin; Kim, Ki Woo; Kim, Min-Seon

    2016-04-01

    Leptin is the most critical hormone in the homeostatic regulation of energy balance among those so far discovered. Leptin primarily acts on the neurons of the mediobasal part of hypothalamus to regulate food intake, thermogenesis, and the blood glucose level. In the hypothalamic neurons, leptin binding to the long form leptin receptors on the plasma membrane initiates multiple signaling cascades. The signaling pathways known to mediate the actions of leptin include JAK-STAT signaling, PI3K-Akt-FoxO1 signaling, SHP2-ERK signaling, AMPK signaling, and mTOR-S6K signaling. Recent evidence suggests that leptin signaling in hypothalamic neurons is also linked to primary cilia function. On the other hand, signaling molecules/pathways mitigating leptin actions in hypothalamic neurons have been extensively investigated in an effort to treat leptin resistance observed in obesity. These include SOCS3, tyrosine phosphatase PTP1B, and inflammatory signaling pathways such as IKK-NFκB and JNK signaling, and ER stress-mitochondrial signaling. In this review, we discuss leptin signaling pathways in the hypothalamus, with a particular focus on the most recently discovered pathways. PMID:26786898

  11. Leptin signalling pathways in hypothalamic neurons.

    PubMed

    Kwon, Obin; Kim, Ki Woo; Kim, Min-Seon

    2016-04-01

    Leptin is the most critical hormone in the homeostatic regulation of energy balance among those so far discovered. Leptin primarily acts on the neurons of the mediobasal part of hypothalamus to regulate food intake, thermogenesis, and the blood glucose level. In the hypothalamic neurons, leptin binding to the long form leptin receptors on the plasma membrane initiates multiple signaling cascades. The signaling pathways known to mediate the actions of leptin include JAK-STAT signaling, PI3K-Akt-FoxO1 signaling, SHP2-ERK signaling, AMPK signaling, and mTOR-S6K signaling. Recent evidence suggests that leptin signaling in hypothalamic neurons is also linked to primary cilia function. On the other hand, signaling molecules/pathways mitigating leptin actions in hypothalamic neurons have been extensively investigated in an effort to treat leptin resistance observed in obesity. These include SOCS3, tyrosine phosphatase PTP1B, and inflammatory signaling pathways such as IKK-NFκB and JNK signaling, and ER stress-mitochondrial signaling. In this review, we discuss leptin signaling pathways in the hypothalamus, with a particular focus on the most recently discovered pathways.

  12. Gambogic acid inhibits osteoclast formation and ovariectomy-induced osteoporosis by suppressing the JNK, p38 and Akt signalling pathways.

    PubMed

    Ma, Jianjun; Ma, Yan; Liu, Xuqiang; Chen, Shuai; Liu, Chao; Qin, An; Fan, Shunwu

    2015-08-01

    Excessive osteoclast formation and bone resorption are key causes of osteoporosis. Natural compounds can serve as alternative therapeutic agents for the prevention and treatment of osteoporosis, and some natural compounds may have advantages over traditional drugs. In the present paper, we report that the natural compound GBA (gambogic acid), which is bioavailable, effective and less toxic, inhibits osteoclast formation, thereby attenuating osteoclastic bone resorption in vitro. Further in vivo studies demonstrated that GBA prevented ovariectomy-induced bone loss in a dose-dependent manner. Moreover, we demonstrated that GBA suppressed RANKL (receptor activator of nuclear factor κB ligand)-induced JNK (c-Jun N-terminal kinase), p38 and Akt phosphorylation. Taken together, our results demonstrate that GBA inhibits osteoclast formation in vitro and in vivo, suggesting that it is of potential value in the treatment of osteoclast-related diseases.

  13. Curcumin protects ANIT-induced cholestasis through signaling pathway of FXR-regulated bile acid and inflammation.

    PubMed

    Yang, Fan; Tang, Xiaowen; Ding, Lili; Zhou, Yue; Yang, Qiaoling; Gong, Junting; Wang, Guangyun; Wang, Zhengtao; Yang, Li

    2016-01-01

    Cholestasis is a clinically significant symptom and widely associated with liver diseases, however, there are very few effective therapies for cholestasis. Danning tablet (DNT, a Chinese patent medicine preparation) has been clinically used to treat human liver and gallbladder diseases for more than 20 years in China. However, which ingredients of DNT contributed to this beneficial effect and their mechanistic underpinnings have been largely unknown. In the present study, we discovered that DNT not only demonstrated greater benefits for cholecystitis patients after cholecystectomy surgery in clinic but also showed protective effect against alpha-naphthylisothiocyanate (ANIT)-induced cholestasis model in rodent. Curcumin, one major compound derived from DNT, exerted the protective effect against cholestasis through farnesoid X receptor (FXR), which has been focused as potential therapeutic targets for treating cholestasis. The underlying mechanism of curcumin against cholestasis was restoring bile acid homeostasis and antagonizing inflammatory responses in a FXR-dependent manner and in turn contributed to overall cholestasis attenuation. Collectively, curcumin can be served as a potential treatment option for liver injury with cholestasis. PMID:27624003

  14. Curcumin protects ANIT-induced cholestasis through signaling pathway of FXR-regulated bile acid and inflammation

    PubMed Central

    Yang, Fan; Tang, Xiaowen; Ding, Lili; zhou, Yue; Yang, Qiaoling; Gong, Junting; Wang, Guangyun; Wang, Zhengtao; Yang, Li

    2016-01-01

    Cholestasis is a clinically significant symptom and widely associated with liver diseases, however, there are very few effective therapies for cholestasis. Danning tablet (DNT, a Chinese patent medicine preparation) has been clinically used to treat human liver and gallbladder diseases for more than 20 years in China. However, which ingredients of DNT contributed to this beneficial effect and their mechanistic underpinnings have been largely unknown. In the present study, we discovered that DNT not only demonstrated greater benefits for cholecystitis patients after cholecystectomy surgery in clinic but also showed protective effect against alpha-naphthylisothiocyanate (ANIT)-induced cholestasis model in rodent. Curcumin, one major compound derived from DNT, exerted the protective effect against cholestasis through farnesoid X receptor (FXR), which has been focused as potential therapeutic targets for treating cholestasis. The underlying mechanism of curcumin against cholestasis was restoring bile acid homeostasis and antagonizing inflammatory responses in a FXR-dependent manner and in turn contributed to overall cholestasis attenuation. Collectively, curcumin can be served as a potential treatment option for liver injury with cholestasis. PMID:27624003

  15. Novel β-Carboline/Hydroxamic Acid Hybrids Targeting Both Histone Deacetylase and DNA Display High Anticancer Activity via Regulation of the p53 Signaling Pathway.

    PubMed

    Ling, Yong; Xu, Chenjun; Luo, Lin; Cao, Jingyi; Feng, Jiao; Xue, Yu; Zhu, Qing; Ju, Caoyun; Li, Fengzhi; Zhang, Yihua; Zhang, Yanan; Ling, Xiang

    2015-12-10

    A novel series of hybrids from β-carboline and hydroxamic acid were designed and synthesized. Several compounds (5m, 11b-d, and 11h) not only exerted significant antiproliferation activity against four human colorectal cancer (CRC) cell lines but also showed histone deacetylase inhibitory effects in vitro. The most potent compound, 11c, exhibited anticancer potency sevenfold higher than that of SAHA. 11c triggered more significant cancer cell apoptosis than did SAHA by cleavage of both PARP and caspase 3 in a dose-dependent manner. Furthermore, 11c simultaneously increased the acetylation of histone H3 and α-tubulin, enhanced expression of DNA damage markers histone H2AX phosphorylation and p-p53 (Ser15), and activated p53 signaling pathway in HCT116 cells. Finally, 11c showed low acute toxicity in mice and inhibited the growth of implanted human CRC in mice more potently than did SAHA. Together, 11c possessed potent antitumor activity and may be a promising candidate for the potential treatment of human CRC.

  16. Tormentic acid inhibits H2O2-induced oxidative stress and inflammation in rat vascular smooth muscle cells via inhibition of the NF-κB signaling pathway.

    PubMed

    Wang, Yu-Lun; Sun, Gen-Yi; Zhang, Ying; He, Jia-Jun; Zheng, Shen; Lin, Jing-Na

    2016-10-01

    Tormentic acid (TA) is a triterpene isolated from the stem bark of the plant Vochysia divergens and has been reported to exhibit anticancer, anti‑inflammatory and anti‑atherogenic properties. However, the functions of TA in hydrogen peroxide (H2O2)‑induced oxidative stress and inflammation in rat vascular smooth muscle cells (RVSMCs) remain unclear. Therefore, the present study aimed to investigate whether TA suppressed H2O2‑induced oxidative stress and inflammation in RVSMCs, and to determine its molecular mechanisms. The present study demonstrated that TA inhibited reactive oxygen species (ROS) generation, induced H2O2 in RVSMCs, and inhibited H2O2-induced expression of inducible nitric oxide synthase (iNOS) and NADPH oxidase (NOX) in RVSMCs. In addition, TA significantly decreased the production of tumor necrosis factor‑α (TNF‑α), interleukin 6 (IL‑6) and IL‑1β. Furthermore, TA pretreatment prevented nuclear factor‑κB (NF‑κB) subunit p65 phosphorylation and NF‑κB inhibitor α (IκBα) degradation induced by H2O2 in RVSMCs. TA is, therefore, suggested to inhibit H2O2-induced oxidative stress and inflammation in RVSMCs via inhibition of the NF‑κB signaling pathway. TA may have potential as a pharmacological agent in the prevention or treatment of atherosclerosis. PMID:27572426

  17. Chlorogenic acid inhibits hypoxia-induced pulmonary artery smooth muscle cells proliferation via c-Src and Shc/Grb2/ERK2 signaling pathway.

    PubMed

    Li, Qun-Yi; Zhu, Ying-Feng; Zhang, Meng; Chen, Li; Zhang, Zhen; Du, Yong-Li; Ren, Guo-Qiang; Tang, Jian-Min; Zhong, Ming-Kang; Shi, Xiao-Jin

    2015-03-15

    Chlorogenic acid (CGA), abundant in coffee and particular fruits, can modulate hypertension and vascular dysfunction. Hypoxia-induced pulmonary artery smooth muscle cells (PASMCs) proliferation has been tightly linked to vascular remodeling in pulmonary arterial hypertension (PAH). Thus, the present study was designed to investigate the effect of CGA on hypoxia-induced proliferation in cultured rat PASMCs. The data showed that CGA potently inhibited PASMCs proliferation and DNA synthesis induced by hypoxia. These inhibitory effects were associated with G1 cell cycle arrest and down-regulation of cell cycle proteins. Treatment with CGA reduced hypoxia-induced hypoxia inducible factor 1α (HIF-1α) expression and trans-activation. Furthermore, hypoxia-evoked c-Src phosphorylation was inhibited by CGA. In vitro ELISA-based tyrosine kinase assay indicated that CGA was a direct inhibitor of c-Src. Moreover, CGA attenuated physical co-association of c-Src/Shc/Grb2 and ERK2 phosphorylation in PASMCs. These results suggest that CGA inhibits hypoxia-induced proliferation in PASMCs via regulating c-Src-mediated signaling pathway. In vivo investigation showed that chronic CGA treatment inhibits monocrotaline-induced PAH in rats. These findings presented here highlight the possible therapeutic use of CGA in hypoxia-related PAH. PMID:25666384

  18. The Protein Kinase CK2 Mediates Cross-Talk between Auxin- and Salicylic Acid-Signaling Pathways in the Regulation of PINOID Transcription

    PubMed Central

    Armengot, Laia; Caldarella, Eleonora; Marquès-Bueno, Maria Mar; Martínez, M. Carmen

    2016-01-01

    The protein kinase CK2 is a ubiquitous and highly conserved enzyme, the activity of which is vital for eukaryotic cells. We recently demonstrated that CK2 modulates salicylic acid (SA) homeostasis in Arabidopsis thaliana, and that functional interplay between CK2 and SA sustains transcriptional expression of PIN-FORMED (PIN) genes. In this work, we show that CK2 also plays a key role in the transcriptional regulation of PINOID (PID), an AGC protein kinase that modulates the apical/basal localization of auxin-efflux transporters. We show that PID transcription is up-regulated by auxin and by SA and that CK2 is involved in both pathways. On the one hand, CK2 activity is required for proteosome-dependent degradation of AXR3, a member of the AUX/IAA family of auxin transcriptional repressors that must be degraded to activate auxin-responsive gene expression. On the other hand, the role of CK2 in SA homeostasis and, indirectly, in SA-driven PID transcription, was confirmed by using Arabidopsis NahG transgenic plants, which cannot accumulate SA. In conclusion, our results evidence a role for CK2 as a functional link in the negative cross-talk between auxin- and SA-signaling. PMID:27275924

  19. Tormentic acid inhibits H2O2-induced oxidative stress and inflammation in rat vascular smooth muscle cells via inhibition of the NF-κB signaling pathway

    PubMed Central

    Wang, Yu-Lun; Sun, Gen-Yi; Zhang, Ying; He, Jia-Jun; Zheng, Shen; Lin, Jing-Na

    2016-01-01

    Tormentic acid (TA) is a triterpene isolated from the stem bark of the plant Vochysia divergens and has been reported to exhibit anticancer, anti-inflammatory and anti-atherogenic properties. However, the functions of TA in hydrogen peroxide (H2O2)-induced oxidative stress and inflammation in rat vascular smooth muscle cells (RVSMCs) remain unclear. Therefore, the present study aimed to investigate whether TA suppressed H2O2-induced oxidative stress and inflammation in RVSMCs, and to determine its molecular mechanisms. The present study demonstrated that TA inhibited reactive oxygen species (ROS) generation, induced H2O2 in RVSMCs, and inhibited H2O2-induced expression of inducible nitric oxide synthase (iNOS) and NADPH oxidase (NOX) in RVSMCs. In addition, TA significantly decreased the production of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6) and IL-1β. Furthermore, TA pretreatment prevented nuclear factor-κB (NF-κB) subunit p65 phosphorylation and NF-κB inhibitor α (IκBα) degradation induced by H2O2 in RVSMCs. TA is, therefore, suggested to inhibit H2O2-induced oxidative stress and inflammation in RVSMCs via inhibition of the NF-κB signaling pathway. TA may have potential as a pharmacological agent in the prevention or treatment of atherosclerosis. PMID:27572426

  20. The Protein Kinase CK2 Mediates Cross-Talk between Auxin- and Salicylic Acid-Signaling Pathways in the Regulation of PINOID Transcription.

    PubMed

    Armengot, Laia; Caldarella, Eleonora; Marquès-Bueno, Maria Mar; Martínez, M Carmen

    2016-01-01

    The protein kinase CK2 is a ubiquitous and highly conserved enzyme, the activity of which is vital for eukaryotic cells. We recently demonstrated that CK2 modulates salicylic acid (SA) homeostasis in Arabidopsis thaliana, and that functional interplay between CK2 and SA sustains transcriptional expression of PIN-FORMED (PIN) genes. In this work, we show that CK2 also plays a key role in the transcriptional regulation of PINOID (PID), an AGC protein kinase that modulates the apical/basal localization of auxin-efflux transporters. We show that PID transcription is up-regulated by auxin and by SA and that CK2 is involved in both pathways. On the one hand, CK2 activity is required for proteosome-dependent degradation of AXR3, a member of the AUX/IAA family of auxin transcriptional repressors that must be degraded to activate auxin-responsive gene expression. On the other hand, the role of CK2 in SA homeostasis and, indirectly, in SA-driven PID transcription, was confirmed by using Arabidopsis NahG transgenic plants, which cannot accumulate SA. In conclusion, our results evidence a role for CK2 as a functional link in the negative cross-talk between auxin- and SA-signaling. PMID:27275924

  1. Evidence for the involvement of retinoic acid receptor RAR alpha-dependent signaling pathway in the induction of tissue transglutaminase and apoptosis by retinoids.

    PubMed

    Zhang, L X; Mills, K J; Dawson, M I; Collins, S J; Jetten, A M

    1995-03-17

    In this study, we show that all-trans-retinoic acid (RA) is a potent inducer of tissue transglutaminase (TGase II) and apoptosis in the rat tracheobronchial epithelial cell line SPOC-1. We demonstrate that these cells express the retinoid receptors RAR alpha, RAR gamma, and RXR beta. To identify which of these receptors are involved in regulating these processes, we analyzed the effects of several receptor-selective agonists, an antagonist, and a dominant-negative RAR alpha. We show that the RAR-selective retinoid SRI-6751-84 strongly increased TGase II expression at both the protein and mRNA levels, whereas the RXR-selective retinoid SR11217 had little effect. The RAR alpha-selective retinoid Ro40-6055 was also able to induce TGase II, whereas the RAR gamma-selective retinoid CD437 was inactive. The induction of TGase II by the RAR-selective retinoid was completely inhibited by the RAR alpha-antagonist Ro41-5253. Overexpression of a truncated RAR alpha gene with dominant-negative activity also inhibited the induction of TGase II expression. The increase in TGase II is associated with an induction of apoptosis as revealed by DNA fragmentation and the generation of apoptotic cells. We demonstrate that apoptosis is affected by retinoids in a manner similar to TGase II. Our results suggest that the induction of TGase II expression and apoptosis in SPOC-1 cells are mediated through an RAR alpha-dependent signaling pathway.

  2. Tormentic acid inhibits H2O2-induced oxidative stress and inflammation in rat vascular smooth muscle cells via inhibition of the NF-κB signaling pathway.

    PubMed

    Wang, Yu-Lun; Sun, Gen-Yi; Zhang, Ying; He, Jia-Jun; Zheng, Shen; Lin, Jing-Na

    2016-10-01

    Tormentic acid (TA) is a triterpene isolated from the stem bark of the plant Vochysia divergens and has been reported to exhibit anticancer, anti‑inflammatory and anti‑atherogenic properties. However, the functions of TA in hydrogen peroxide (H2O2)‑induced oxidative stress and inflammation in rat vascular smooth muscle cells (RVSMCs) remain unclear. Therefore, the present study aimed to investigate whether TA suppressed H2O2‑induced oxidative stress and inflammation in RVSMCs, and to determine its molecular mechanisms. The present study demonstrated that TA inhibited reactive oxygen species (ROS) generation, induced H2O2 in RVSMCs, and inhibited H2O2-induced expression of inducible nitric oxide synthase (iNOS) and NADPH oxidase (NOX) in RVSMCs. In addition, TA significantly decreased the production of tumor necrosis factor‑α (TNF‑α), interleukin 6 (IL‑6) and IL‑1β. Furthermore, TA pretreatment prevented nuclear factor‑κB (NF‑κB) subunit p65 phosphorylation and NF‑κB inhibitor α (IκBα) degradation induced by H2O2 in RVSMCs. TA is, therefore, suggested to inhibit H2O2-induced oxidative stress and inflammation in RVSMCs via inhibition of the NF‑κB signaling pathway. TA may have potential as a pharmacological agent in the prevention or treatment of atherosclerosis.

  3. Xenobiotic- and Jasmonic Acid-Inducible Signal Transduction Pathways Have Become Interdependent at the Arabidopsis CYP81D11 Promoter1[C][W

    PubMed Central

    Köster, Julia; Thurow, Corinna; Kruse, Kerstin; Meier, Alexander; Iven, Tim; Feussner, Ivo; Gatz, Christiane

    2012-01-01

    Plants modify harmful substances through an inducible detoxification system. In Arabidopsis (Arabidopsis thaliana), chemical induction of the cytochrome P450 gene CYP81D11 and other genes linked to the detoxification program depends on class II TGA transcription factors. CYP81D11 expression is also induced by the phytohormone jasmonic acid (JA) through the established pathway requiring the JA receptor CORONATINE INSENSITIVE1 (COI1) and the JA-regulated transcription factor MYC2. Here, we report that the xenobiotic- and the JA-dependent signal cascades have become interdependent at the CYP81D11 promoter. On the one hand, MYC2 can only activate the expression of CYP81D11 when both the MYC2- and the TGA-binding sites are present in the promoter. On the other hand, the xenobiotic-regulated class II TGA transcription factors can only mediate maximal promoter activity if TGA and MYC2 binding motifs, MYC2, and the JA-isoleucine biosynthesis enzymes DDE2/AOS and JAR1 are functional. Since JA levels and degradation of JAZ1, a repressor of the JA response, are not affected by reactive chemicals, we hypothesize that basal JA signaling amplifies the response to chemical stress. Remarkably, stress-induced expression levels were 3-fold lower in coi1 than in the JA biosynthesis mutant dede2-2, revealing that COI1 can contribute to the activation of the promoter in the absence of JA. Moreover, we show that deletion of the MYC2 binding motifs abolishes the JA responsiveness of the promoter but not the responsiveness to COI1. These findings suggest that yet unknown cis-element(s) can mediate COI1-dependent transcriptional activation in the absence of JA. PMID:22452854

  4. Eicosapentaenoic acid-enriched phosphatidylcholine isolated from Cucumaria frondosa exhibits anti-hyperglycemic effects via activating phosphoinositide 3-kinase/protein kinase B signal pathway.

    PubMed

    Hu, Shiwei; Xu, Leilei; Shi, Di; Wang, Jingfeng; Wang, Yuming; Lou, Qiaoming; Xue, Changhu

    2014-04-01

    Eicosapentaenoic acid-enriched phosphatidylcholine was isolated from the sea cucumber Cucumaria frondosa (Cucumaria-PC) and its effects on streptozotocin (STZ)-induced hyperglycemic rats were investigated. Male Sprague-Dawley rats were randomly divided into normal control, model control (STZ), low- and high-dose Cucumaria-PC groups (STZ + Cucumaria-PC at 25 and 75 mg/Kg·b·wt, intragastrically, respectively). Blood glucose, insulin, glycogen in liver and gastrocnemius were determined over 60 days. Insulin signaling in the rats' gastrocnemius was determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting. The results showed that Cucumaria-PC significantly decreased blood glucose level, increased insulin secretion and glycogen synthesis in diabetic rats. RT-PCR analysis revealed that Cucumaria-PC significantly promoted the expressions of glycometabolism-related genes of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), phosphoinositide 3-kinase (PI3K), protein kinase B (PKB), and glucose transporter 4 (GLUT4) in gastrocnemius. Western blotting assay demonstrated that Cucumaria-PC remarkably enhanced the proteins abundance of IR-β, PI3K, PKB, GLUT4, as well as phosphorylation of Tyr-IR-β, p85-PI3K, Ser473-PKB (P < 0.05 and P < 0.01). These findings suggested that Cucumaria-PC exhibited significant anti-hyperglycemic activities through up-regulating PI3K/PKB signal pathway mediated by insulin. Nutritional supplementation with Cucumaria-PC, if validated for human studies, may offer an adjunctive therapy for diabetes mellitus.

  5. LXR signaling pathways and atherosclerosis

    PubMed Central

    Calkin, Anna; Tontonoz, Peter

    2010-01-01

    First discovered as orphan receptors, liver X receptors (LXRs) were subsequently identified as the nuclear receptor target of the cholesterol metabolites, oxysterols.1 There are 2 LXR receptors encoded by distinct genes: LXRα is most highly expressed in the liver, adipose, kidney, adrenal tissues and macrophages, and LXRβ is ubiquitously expressed. Despite differential tissue distribution, these isoforms have 78% homology in their ligand-binding domain and appear to respond to the same endogenous ligands. Work over the past 10 years has shown that the LXR pathway regulates lipid metabolism and inflammation via both the induction and repression of target genes. Given the importance of cholesterol regulation and inflammation in the development of cardiovascular disease, it is not surprising that activation of the LXR pathway attenuates various mechanisms underlying atherosclerotic plaque development.2 In this minireview we will discuss the impact of the LXR pathway on both cholesterol metabolism and atherosclerosis. PMID:20631351

  6. Signaling Pathways Related to Protein Synthesis and Amino Acid Concentration in Pig Skeletal Muscles Depend on the Dietary Protein Level, Genotype and Developmental Stages.

    PubMed

    Liu, Yingying; Li, Fengna; Kong, Xiangfeng; Tan, Bie; Li, Yinghui; Duan, Yehui; Blachier, François; Hu, Chien-An A; Yin, Yulong

    2015-01-01

    Muscle growth is regulated by the homeostatic balance of the biosynthesis and degradation of muscle proteins. To elucidate the molecular interactions among diet, pig genotype, and physiological stage, we examined the effect of dietary protein concentration, pig genotype, and physiological stages on amino acid (AA) pools, protein deposition, and related signaling pathways in different types of skeletal muscles. The study used 48 Landrace pigs and 48 pure-bred Bama mini-pigs assigned to each of 2 dietary treatments: lower/GB (Chinese conventional diet)- or higher/NRC (National Research Council)-protein diet. Diets were fed from 5 weeks of age to respective market weights of each genotype. Samples of biceps femoris muscle (BFM, type I) and longissimus dorsi muscle (LDM, type II) were collected at nursery, growing, and finishing phases according to the physiological stage of each genotype, to determine the AA concentrations, mRNA levels for growth-related genes in muscles, and protein abundances of mechanistic target of rapamycin (mTOR) signaling pathway. Our data showed that the concentrations of most AAs in LDM and BFM of pigs increased (P<0.05) gradually with increasing age. Bama mini-pigs had generally higher (P<0.05) muscle concentrations of flavor-related AA, including Met, Phe, Tyr, Pro, and Ser, compared with Landrace pigs. The mRNA levels for myogenic determining factor, myogenin, myocyte-specific enhancer binding factor 2 A, and myostatin of Bama mini-pigs were higher (P<0.05) than those of Landrace pigs, while total and phosphorylated protein levels for protein kinase B, mTOR, and p70 ribosomal protein S6 kinases (p70S6K), and ratios of p-mTOR/mTOR, p-AKT/AKT, and p-p70S6K/p70S6K were lower (P<0.05). There was a significant pig genotype-dependent effect of dietary protein on the levels for mTOR and p70S6K. When compared with the higher protein-NRC diet, the lower protein-GB diet increased (P<0.05) the levels for mTOR and p70S6K in Bama mini-pigs, but

  7. Modularized TGFbeta-Smad Signaling Pathway

    NASA Technical Reports Server (NTRS)

    Li, Yongfeng; Wang, M.; Carra, C.; Cucinotta, F. A.

    2011-01-01

    The Transforming Growth Factor beta (TGFbeta) signaling pathway is a prominent regulatory signaling pathway controlling various important cellular processes. It can be induced by several factors, including ionizing radiation. It is regulated by Smads in a negative feedback loop through promoting increases in the regulatory Smads in the cell nucleus, and subsequent expression of inhibitory Smad, Smad7 to form a ubiquitin ligase with Smurf targeting active TGF receptors for degradation. In this work, we proposed a mathematical model to study the radiation-induced Smad-regulated TGF signaling pathway. By modularization, we are able to analyze each module (subsystem) and recover the nonlinear dynamics of the entire network system. Meanwhile the excitability, a common feature observed in the biological systems, along the TGF signaling pathway is discussed by mathematical analysis and numerical simulation.

  8. Premetazoan origin of the Hippo signaling pathway

    PubMed Central

    Sebé-Pedrós, Arnau; Zheng, Yonggang; Ruiz-Trillo, Iñaki; Pan, Duojia

    2012-01-01

    Summary Non-aggregative multicellularity requires strict control of cell number. The Hippo signaling pathway coordinates cell proliferation and apoptosis and is a central regulator of organ size in animals. Recent studies have shown the presence of key members of the Hippo pathway in non-bilaterian animals, but failed to identify this pathway outside Metazoa. Through comparative analyses of recently sequenced holozoan genomes, we show that Hippo pathway components, such as the kinases Hippo and Warts, the co-activator Yorkie and the transcription factor Scalloped, were already present in the unicellular ancestors of animals. Remarkably, functional analysis of Hippo components of the amoeboid holozoan Capsaspora owczarzaki, performed in Drosophila, demonstrate that the growth-regulatory activity of the Hippo pathway is conserved in this unicellular lineage. Our findings show that the Hippo pathway evolved well before the origin of Metazoa and highlight the importance of Hippo signaling as a key developmental mechanism pre-dating the origin of Metazoa. PMID:22832104

  9. Optogenetic control of intracellular signaling pathways.

    PubMed

    Zhang, Kai; Cui, Bianxiao

    2015-02-01

    Cells employ a plethora of signaling pathways to make their life-and-death decisions. Extensive genetic, biochemical, and physiological studies have led to the accumulation of knowledge about signaling components and their interactions within signaling networks. These conventional approaches, although useful, lack the ability to control the spatial and temporal aspects of signaling processes. The recently emerged optogenetic tools open exciting opportunities by enabling signaling regulation with superior temporal and spatial resolution, easy delivery, rapid reversibility, fewer off-target side effects, and the ability to dissect complex signaling networks. Here we review recent achievements in using light to control intracellular signaling pathways and discuss future prospects for the field, including integration of new genetic approaches into optogenetics.

  10. Optogenetic control of intracellular signaling pathways

    PubMed Central

    Zhang, Kai; Cui, Bianxiao

    2014-01-01

    Cells employ a plethora of signaling pathways to make their life-and-death decisions. Extensive genetic, biochemical, and physiological studies have led to the accumulation of knowledge about signaling components and their interactions within signaling networks. These conventional approaches, though useful, lack the ability to control the spatial and temporal aspects of signaling processes. The recently emerged optogenetic tools open up exciting opportunities by enabling signaling regulation with superior temporal and spatial resolution, easy delivery, rapid reversibility, fewer off-target side effects, and the ability to dissect complex signaling networks. Here we review recent achievements in using light to control intracellular signaling pathways, and discuss future prospects for the field, including integration of new genetic approaches into optogenetics. PMID:25529484

  11. Arabidopsis GLUTATHIONE REDUCTASE1 plays a crucial role in leaf responses to intracellular hydrogen peroxide and in ensuring appropriate gene expression through both salicylic acid and jasmonic acid signaling pathways.

    PubMed

    Mhamdi, Amna; Hager, Jutta; Chaouch, Sejir; Queval, Guillaume; Han, Yi; Taconnat, Ludivine; Saindrenan, Patrick; Gouia, Houda; Issakidis-Bourguet, Emmanuelle; Renou, Jean-Pierre; Noctor, Graham

    2010-07-01

    Glutathione is a major cellular thiol that is maintained in the reduced state by glutathione reductase (GR), which is encoded by two genes in Arabidopsis (Arabidopsis thaliana; GR1 and GR2). This study addressed the role of GR1 in hydrogen peroxide (H(2)O(2)) responses through a combined genetic, transcriptomic, and redox profiling approach. To identify the potential role of changes in glutathione status in H(2)O(2) signaling, gr1 mutants, which show a constitutive increase in oxidized glutathione (GSSG), were compared with a catalase-deficient background (cat2), in which GSSG accumulation is conditionally driven by H(2)O(2). Parallel transcriptomics analysis of gr1 and cat2 identified overlapping gene expression profiles that in both lines were dependent on growth daylength. Overlapping genes included phytohormone-associated genes, in particular implicating glutathione oxidation state in the regulation of jasmonic acid signaling. Direct analysis of H(2)O(2)-glutathione interactions in cat2 gr1 double mutants established that GR1-dependent glutathione status is required for multiple responses to increased H(2)O(2) availability, including limitation of lesion formation, accumulation of salicylic acid, induction of pathogenesis-related genes, and signaling through jasmonic acid pathways. Modulation of these responses in cat2 gr1 was linked to dramatic GSSG accumulation and modified expression of specific glutaredoxins and glutathione S-transferases, but there is little or no evidence of generalized oxidative stress or changes in thioredoxin-associated gene expression. We conclude that GR1 plays a crucial role in daylength-dependent redox signaling and that this function cannot be replaced by the second Arabidopsis GR gene or by thiol systems such as the thioredoxin system.

  12. Advances in Targeting Signal Transduction Pathways

    PubMed Central

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

    2012-01-01

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

  13. Retinoic Acid Ameliorates Pancreatic Fibrosis and Inhibits the Activation of Pancreatic Stellate Cells in Mice with Experimental Chronic Pancreatitis via Suppressing the Wnt/β-Catenin Signaling Pathway

    PubMed Central

    Yin, Guojian; Fan, Yuting; Wu, Deqing; Qiu, Lei; Yu, Ge; Xing, Miao; Hu, Guoyong; Wang, Xingpeng; Wan, Rong

    2015-01-01

    Pancreatic fibrosis, a prominent feature of chronic pancreatitis (CP), induces persistent and permanent damage in the pancreas. Pancreatic stellate cells (PSCs) provide a major source of extracellular matrix (ECM) deposition during pancreatic injury, and persistent activation of PSCs plays a vital role in the progression of pancreatic fibrosis. Retinoic acid (RA), a retinoid, has a broad range of biological functions, including regulation of cell differentiation and proliferation, attenuating progressive fibrosis of multiple organs. In the present study, we investigated the effects of RA on fibrosis in experimental CP and cultured PSCs. CP was induced in mice by repetitive cerulein injection in vivo, and mouse PSCs were isolated and activated in vitro. Suppression of pancreatic fibrosis upon administration of RA was confirmed based on reduction of histological damage, α-smooth muscle actin (α-SMA) expression and mRNA levels of β-catenin, platelet-derived growth factor (PDGF)-Rβ transforming growth factor (TGF)-βRII and collagen 1α1 in vivo. Wnt 2 and β-catenin protein levels were markedly down-regulated, while Axin 2 expression level was up-regulated in the presence of RA, both in vivo and in vitro. Nuclear translation of β-catenin was significantly decreased following RA treatment, compared with cerulein-induced CP in mice and activated PSCs. Furthermore, RA induced significant PSC apoptosis, inhibited proliferation, suppressed TCF/LEF-dependent transcriptional activity and ECM production of PSC via down-regulation of TGFβRII, PDGFRβ and collagen 1α1 in vitro. These results indicate a critical role of the Wnt/β-catenin signaling pathway in RA-induced effects on CP and PSC regulation and support the potential of RA as a suppressor of pancreatic fibrosis in mice. PMID:26556479

  14. β-1,3 Glucan Sulfate, but Not β-1,3 Glucan, Induces the Salicylic Acid Signaling Pathway in Tobacco and Arabidopsis

    PubMed Central

    Ménard, Rozenn; Alban, Susanne; de Ruffray, Patrice; Jamois, Frank; Franz, Gerhard; Fritig, Bernard; Yvin, Jean-Claude; Kauffmann, Serge

    2004-01-01

    Sulfate substituents naturally occurring in biomolecules, such as oligosaccharides and polysaccharides, can play a critical role in major physiological functions in plants and animals. We show that laminarin, a β-1,3 glucan with elicitor activity in tobacco (Nicotiana tabacum), becomes, after chemical sulfation, an inducer of the salicylic acid (SA) signaling pathway in tobacco and Arabidopsis thaliana. In tobacco cell suspensions, the oxidative burst induced by the laminarin sulfate PS3 was Ca2+ dependent but partially kinase independent, whereas laminarin triggered a strickly kinase-dependent oxidative burst. Cells treated with PS3 or laminarin remained fully responsive to a second application of laminarin or PS3, respectively, suggesting two distinct perception systems. In tobacco leaves, PS3, but not laminarin, caused electrolyte leakage and triggered scopoletin and SA accumulation. Expression of different families of Pathogenesis-Related (PR) proteins was analyzed in wild-type and mutant tobacco as well as in Arabidopsis. Laminarin induced expression of ethylene-dependent PR proteins, whereas PS3 triggered expression of ethylene- and SA-dependent PR proteins. In Arabidopsis, PS3-induced PR1 expression was also NPR1 (for nonexpressor of PR genes1) dependent. Structure-activity analysis revealed that (1) a minimum chain length is essential for biological activity of unsulfated as well as sulfated laminarin, (2) the sulfate residues are essential and cannot be replaced by other anionic groups, and (3) moderately sulfated β-1,3 glucans are active. In tobacco, PS3 and curdlan sulfate induced immunity against Tobacco mosaic virus infection, whereas laminarin induced only a weak resistance. The results open new routes to work out new molecules suitable for crop protection. PMID:15494557

  15. Betulinic acid alleviates non-alcoholic fatty liver by inhibiting SREBP1 activity via the AMPK-mTOR-SREBP signaling pathway.

    PubMed

    Quan, Hai Yan; Kim, Do Yeon; Kim, Soo Jung; Jo, Hee Kyung; Kim, Go Woon; Chung, Sung Hyun

    2013-05-01

    Non-alcoholic fatty liver disease (NAFLD) is emerging as the most common liver disease in industrialized countries. The discovery of food components that can ameliorate NAFLD is therefore of interest. Betulinic acid (BA) is a triterpenoid with many pharmacological activities, but the effect of BA on fatty liver is as yet unknown. To explore the possible anti-fatty liver effects and their underlying mechanisms, we used insulin-resistant HepG2 cells, primary rat hepatocytes and liver tissue from ICR mice fed a high-fat diet (HFD). Oil Red O staining revealed that BA significantly suppressed excessive triglyceride accumulation in HepG2 cells and in the livers of mice fed a HFD. Ca(+2)-calmodulin dependent protein kinase kinase (CAMKK) and AMP-activated protein kinase (AMPK) were both activated by BA treatment. In contrast, the protein levels of sterol regulatory element-binding protein 1 (SREBP1), mammalian target of rapamycin (mTOR) and S6 kinase (S6K) were all reduced when hepatocytes were treated with BA for up to 24h. We found that BA activates AMPK via phosphorylation, suppresses SREBP1 mRNA expression, nuclear translocation and repressed SREBP1 target gene expression in HepG2 cells and primary hepatocytes, leading to reduced lipogenesis and lipid accumulation. These effects were completely abolished in the presence of STO-609 (a CAMKK inhibitor) or compound C (an AMPK inhibitor), indicating that the BA-induced reduction in hepatic steatosis was mediated via the CAMKK-AMPK-SREBP1 signaling pathway. Taken together, our results suggest that BA effectively ameliorates intracellular lipid accumulation in liver cells and thus is a potential therapeutic agent for the prevention of fatty liver disease. PMID:23435355

  16. Retinoic Acid Ameliorates Pancreatic Fibrosis and Inhibits the Activation of Pancreatic Stellate Cells in Mice with Experimental Chronic Pancreatitis via Suppressing the Wnt/β-Catenin Signaling Pathway.

    PubMed

    Xiao, Wenqin; Jiang, Weiliang; Shen, Jie; Yin, Guojian; Fan, Yuting; Wu, Deqing; Qiu, Lei; Yu, Ge; Xing, Miao; Hu, Guoyong; Wang, Xingpeng; Wan, Rong

    2015-01-01

    Pancreatic fibrosis, a prominent feature of chronic pancreatitis (CP), induces persistent and permanent damage in the pancreas. Pancreatic stellate cells (PSCs) provide a major source of extracellular matrix (ECM) deposition during pancreatic injury, and persistent activation of PSCs plays a vital role in the progression of pancreatic fibrosis. Retinoic acid (RA), a retinoid, has a broad range of biological functions, including regulation of cell differentiation and proliferation, attenuating progressive fibrosis of multiple organs. In the present study, we investigated the effects of RA on fibrosis in experimental CP and cultured PSCs. CP was induced in mice by repetitive cerulein injection in vivo, and mouse PSCs were isolated and activated in vitro. Suppression of pancreatic fibrosis upon administration of RA was confirmed based on reduction of histological damage, α-smooth muscle actin (α-SMA) expression and mRNA levels of β-catenin, platelet-derived growth factor (PDGF)-Rβ transforming growth factor (TGF)-βRII and collagen 1α1 in vivo. Wnt 2 and β-catenin protein levels were markedly down-regulated, while Axin 2 expression level was up-regulated in the presence of RA, both in vivo and in vitro. Nuclear translation of β-catenin was significantly decreased following RA treatment, compared with cerulein-induced CP in mice and activated PSCs. Furthermore, RA induced significant PSC apoptosis, inhibited proliferation, suppressed TCF/LEF-dependent transcriptional activity and ECM production of PSC via down-regulation of TGFβRII, PDGFRβ and collagen 1α1 in vitro. These results indicate a critical role of the Wnt/β-catenin signaling pathway in RA-induced effects on CP and PSC regulation and support the potential of RA as a suppressor of pancreatic fibrosis in mice. PMID:26556479

  17. Inhibition of de novo Palmitate Synthesis by Fatty Acid Synthase Induces Apoptosis in Tumor Cells by Remodeling Cell Membranes, Inhibiting Signaling Pathways, and Reprogramming Gene Expression

    PubMed Central

    Ventura, Richard; Mordec, Kasia; Waszczuk, Joanna; Wang, Zhaoti; Lai, Julie; Fridlib, Marina; Buckley, Douglas; Kemble, George; Heuer, Timothy S.

    2015-01-01

    Inhibition of de novo palmitate synthesis via fatty acid synthase (FASN) inhibition provides an unproven approach to cancer therapy with a strong biological rationale. FASN expression increases with tumor progression and associates with chemoresistance, tumor metastasis, and diminished patient survival in numerous tumor types. TVB-3166, an orally-available, reversible, potent, and selective FASN inhibitor induces apoptosis, inhibits anchorage-independent cell growth under lipid-rich conditions, and inhibits in-vivo xenograft tumor growth. Dose-dependent effects are observed between 20–200 nM TVB-3166, which agrees with the IC50 in biochemical FASN and cellular palmitate synthesis assays. Mechanistic studies show that FASN inhibition disrupts lipid raft architecture, inhibits biological pathways such as lipid biosynthesis, PI3K–AKT–mTOR and β-catenin signal transduction, and inhibits expression of oncogenic effectors such as c-Myc; effects that are tumor-cell specific. Our results demonstrate that FASN inhibition has anti-tumor activities in biologically diverse preclinical tumor models and provide mechanistic and pharmacologic evidence that FASN inhibition presents a promising therapeutic strategy for treating a variety of cancers, including those expressing mutant K-Ras, ErbB2, c-Met, and PTEN. The reported findings inform ongoing studies to link mechanisms of action with defined tumor types and advance the discovery of biomarkers supporting development of FASN inhibitors as cancer therapeutics. Research in context Fatty acid synthase (FASN) is a vital enzyme in tumor cell biology; the over-expression of FASN is associated with diminished patient prognosis and resistance to many cancer therapies. Our data demonstrate that selective and potent FASN inhibition with TVB-3166 leads to selective death of tumor cells, without significant effect on normal cells, and inhibits in vivo xenograft tumor growth at well-tolerated doses. Candidate biomarkers for

  18. Logical modelling of Drosophila signalling pathways.

    PubMed

    Mbodj, Abibatou; Junion, Guillaume; Brun, Christine; Furlong, Eileen E M; Thieffry, Denis

    2013-09-01

    A limited number of signalling pathways are involved in the specification of cell fate during the development of all animals. Several of these pathways were originally identified in Drosophila. To clarify their roles, and possible cross-talk, we have built a logical model for the nine key signalling pathways recurrently used in metazoan development. In each case, we considered the associated ligands, receptors, signal transducers, modulators, and transcription factors reported in the literature. Implemented using the logical modelling software GINsim, the resulting models qualitatively recapitulate the main characteristics of each pathway, in wild type as well as in various mutant situations (e.g. loss-of-function or gain-of-function). These models constitute pluggable modules that can be used to assemble comprehensive models of complex developmental processes. Moreover, these models of Drosophila pathways could serve as scaffolds for more complicated models of orthologous mammalian pathways. Comprehensive model annotations and GINsim files are provided for each of the nine considered pathways.

  19. The Hedgehog signalling pathway in bone formation

    PubMed Central

    Yang, Jing; Andre, Philipp; Ye, Ling; Yang, Ying-Zi

    2015-01-01

    The Hedgehog (Hh) signalling pathway plays many important roles in development, homeostasis and tumorigenesis. The critical function of Hh signalling in bone formation has been identified in the past two decades. Here, we review the evolutionarily conserved Hh signalling mechanisms with an emphasis on the functions of the Hh signalling pathway in bone development, homeostasis and diseases. In the early stages of embryonic limb development, Sonic Hedgehog (Shh) acts as a major morphogen in patterning the limb buds. Indian Hedgehog (Ihh) has an essential function in endochondral ossification and induces osteoblast differentiation in the perichondrium. Hh signalling is also involved intramembrane ossification. Interactions between Hh and Wnt signalling regulate cartilage development, endochondral bone formation and synovial joint formation. Hh also plays an important role in bone homeostasis, and reducing Hh signalling protects against age-related bone loss. Disruption of Hh signalling regulation leads to multiple bone diseases, such as progressive osseous heteroplasia. Therefore, understanding the signalling mechanisms and functions of Hh signalling in bone development, homeostasis and diseases will provide important insights into bone disease prevention, diagnoses and therapeutics. PMID:26023726

  20. Citric acid induces cell-cycle arrest and apoptosis of human immortalized keratinocyte cell line (HaCaT) via caspase- and mitochondrial-dependent signaling pathways.

    PubMed

    Ying, Tsung-Ho; Chen, Chia-Wei; Hsiao, Yu-Ping; Hung, Sung-Jen; Chung, Jing-Gung; Yang, Jen-Hung

    2013-10-01

    Citric acid is an alpha-hydroxyacid (AHA) widely used in cosmetic dermatology and skincare products. However, there is concern regarding its safety for the skin. In this study, we investigated the cytotoxic effects of citric acid on the human keratinocyte cell line HaCaT. HaCaT cells were treated with citric acid at 2.5-12.5 mM for different time periods. Cell-cycle arrest and apoptosis were investigated by 4,6-diamidino-2-phenylindole dihydrochloride (DAPI) staining, flow cytometry, western blot and confocal microscopy. Citric acid not only inhibited proliferation of HaCaT cells in a dose-dependent manner, but also induced apoptosis and cell cycle-arrest at the G2/M phase (before 24 h) and S phase (after 24 h). Citric acid increased the level of Bcl-2-associated X protein (BAX) and reduced the levels of B-cell lymphoma-2 (BCL-2), B-cell lymphoma-extra large (BCL-XL) and activated caspase-9 and caspase-3, which subsequently induced apoptosis via caspase-dependent and caspase-independent pathways. Citric acid also activated death receptors and increased the levels of caspase-8, activated BH3 interacting-domain death agonist (BID) protein, Apoptosis-inducing factor (AIF), and Endonuclease G (EndoG). Therefore, citric acid induces apoptosis through the mitochondrial pathway in the human keratinocyte cell line HaCaT. The study results suggest that citric acid is cytotoxic to HaCaT cells via induction of apoptosis and cell-cycle arrest in vitro.

  1. Signaling Pathways Related to Protein Synthesis and Amino Acid Concentration in Pig Skeletal Muscles Depend on the Dietary Protein Level, Genotype and Developmental Stages

    PubMed Central

    Liu, Yingying; Li, Fengna; Kong, Xiangfeng; Tan, Bie; Li, Yinghui; Duan, Yehui; Blachier, François; Hu, Chien-An A.; Yin, Yulong

    2015-01-01

    Muscle growth is regulated by the homeostatic balance of the biosynthesis and degradation of muscle proteins. To elucidate the molecular interactions among diet, pig genotype, and physiological stage, we examined the effect of dietary protein concentration, pig genotype, and physiological stages on amino acid (AA) pools, protein deposition, and related signaling pathways in different types of skeletal muscles. The study used 48 Landrace pigs and 48 pure-bred Bama mini-pigs assigned to each of 2 dietary treatments: lower/GB (Chinese conventional diet)- or higher/NRC (National Research Council)-protein diet. Diets were fed from 5 weeks of age to respective market weights of each genotype. Samples of biceps femoris muscle (BFM, type I) and longissimus dorsi muscle (LDM, type II) were collected at nursery, growing, and finishing phases according to the physiological stage of each genotype, to determine the AA concentrations, mRNA levels for growth-related genes in muscles, and protein abundances of mechanistic target of rapamycin (mTOR) signaling pathway. Our data showed that the concentrations of most AAs in LDM and BFM of pigs increased (P<0.05) gradually with increasing age. Bama mini-pigs had generally higher (P<0.05) muscle concentrations of flavor-related AA, including Met, Phe, Tyr, Pro, and Ser, compared with Landrace pigs. The mRNA levels for myogenic determining factor, myogenin, myocyte-specific enhancer binding factor 2 A, and myostatin of Bama mini-pigs were higher (P<0.05) than those of Landrace pigs, while total and phosphorylated protein levels for protein kinase B, mTOR, and p70 ribosomal protein S6 kinases (p70S6K), and ratios of p-mTOR/mTOR, p-AKT/AKT, and p-p70S6K/p70S6K were lower (P<0.05). There was a significant pig genotype-dependent effect of dietary protein on the levels for mTOR and p70S6K. When compared with the higher protein-NRC diet, the lower protein-GB diet increased (P<0.05) the levels for mTOR and p70S6K in Bama mini-pigs, but

  2. Abnormalities in signaling pathways in diabetic nephropathy

    PubMed Central

    Brosius, Frank C; Khoury, Charbel C; Buller, Carolyn L; Chen, Sheldon

    2010-01-01

    Diabetic nephropathy (DN) is characterized by a plethora of signaling abnormalities that together ultimately result in the clinical and pathologic hallmarks of DN, namely progressive albuminuria followed by a gradual decline in glomerular filtration rate leading to kidney failure, and accompanied by podocyte loss, progressive glomerular sclerosis and, ultimately, progressive tubulointerstitial fibrosis. Over the past few years, the general understanding of the abnormalities in signaling pathways that lead to DN has expanded considerably. In this review, some of the important pathways that appear to be involved in driving this process are discussed, with special emphasis on newer findings and insights. Newer concepts regarding signaling changes in bradykinin, mTOR, JAK/STAT, MCP-1, VEGF, endothelial nitric oxide synthase, activated protein C and other pathways are discussed. PMID:20224802

  3. [Wnt signalling pathway and cervical cancer].

    PubMed

    Ramos-Solano, Moisés; Álvarez-Zavala, Monserrat; García-Castro, Beatriz; Jave-Suárez, Luis Felipe; Aguilar-Lemarroy, Adriana

    2015-01-01

    Cervical cancer (CC) is a pathology that arises in the cervical epithelium, whose major cause of risk is human papillomavirus (HPV) infection. Due to the fact that HPV infection per se is not enough to generate a carcinogenic process, it has been proposed that alterations in the Wnt signaling pathway are involved in cervical carcinogenesis. The Wnt family consists of 13 receptors and 19 ligands, and it is highly conserved phylogenetically due to its contribution in different biological processes, such as embryogenesis and tissue regeneration. Additionally, this signaling pathway modulates various cellular functions, for instance: cell proliferation, differentiation, migration and cell polarity. This paper describes the Wnt signaling pathways and alterations that have been found in members of this family in different cancer types and, especially, in CC.

  4. Aging of signal transduction pathways, and pathology

    PubMed Central

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

    2008-01-01

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

  5. Canonical WNT signaling pathway and human AREG.

    PubMed

    Katoh, Yuriko; Katoh, Masaru

    2006-06-01

    AREG (Amphiregulin), BTC (beta-cellulin), EGF, EPGN (Epigen), EREG (Epiregulin), HBEGF, NRG1, NRG2, NRG3, NRG4 and TGFA (TGFalpha) constitute EGF family ligands for ERBB family receptors. Cetuximab (Erbitux), Pertuzumab (Omnitarg) and Trastuzumab (Herceptin) are anti-cancer drugs targeted to EGF family ligands, while Gefitinib (Iressa), Erlotinib (Tarceva) and Lapatinib (GW572016) are anti-cancer drugs targeted to ERBB family receptors. AREG and TGFA are biomarkers for Gefitinib non-responders. The TCF/LEF binding sites within the promoter region of human EGF family members were searched for by using bioinformatics and human intelligence (Humint). Because three TCF/LEF-binding sites were identified within the 5'-promoter region of human AREG gene, comparative genomics analyses on AREG orthologs were further performed. The EPGN-EREG-AREG-BTC cluster at human chromosome 4q13.3 was linked to the PPBP-CXCL segmental duplicons. AREG was the paralog of HBEGF at human chromosome 5q31.2. Chimpanzee AREG gene, consisting of six exons, was located within NW_105918.1 genome sequence. Chimpanzee AREG was a type I transmembrane protein showing 98.0% and 71.4% total amino-acid identity with human AREG and mouse Areg, respectively. Three TCF/LEF-binding sites within human AREG promoter were conserved in chimpanzee AREG promoter, but not in rodent Areg promoters. Primate AREG promoters were significantly divergent from rodent Areg promoters. AREG mRNA was expressed in a variety of human tumors, such as colorectal cancer, liver cancer, gastric cancer, breast cancer, prostate cancer, esophageal cancer and myeloma. Because human AREG was characterized as potent target gene of WNT/beta-catenin signaling pathway, WNT signaling activation could lead to Gefitinib resistance through AREG upregulation. AREG is a target of systems medicine in the field of oncology. PMID:16685431

  6. Bile Acid Metabolism and Signaling

    PubMed Central

    Chiang, John Y. L.

    2015-01-01

    Bile acids are important physiological agents for intestinal nutrient absorption and biliary secretion of lipids, toxic metabolites, and xenobiotics. Bile acids also are signaling molecules and metabolic regulators that activate nuclear receptors and G protein-coupled receptor (GPCR) signaling to regulate hepatic lipid, glucose, and energy homeostasis and maintain metabolic homeostasis. Conversion of cholesterol to bile acids is critical for maintaining cholesterol homeostasis and preventing accumulation of cholesterol, triglycerides, and toxic metabolites, and injury in the liver and other organs. Enterohepatic circulation of bile acids from the liver to intestine and back to the liver plays a central role in nutrient absorption and distribution, and metabolic regulation and homeostasis. This physiological process is regulated by a complex membrane transport system in the liver and intestine regulated by nuclear receptors. Toxic bile acids may cause inflammation, apoptosis, and cell death. On the other hand, bile acid-activated nuclear and GPCR signaling protects against inflammation in liver, intestine, and macrophages. Disorders in bile acid metabolism cause cholestatic liver diseases, dyslipidemia, fatty liver diseases, cardiovascular diseases, and diabetes. Bile acids, bile acid derivatives, and bile acid sequestrants are therapeutic agents for treating chronic liver diseases, obesity, and diabetes in humans. PMID:23897684

  7. α-Lipoic acid interaction with dopamine D2 receptor-dependent activation of the Akt/GSK-3β signaling pathway induced by antipsychotics: potential relevance for the treatment of schizophrenia.

    PubMed

    Deslauriers, Jessica; Desmarais, Christian; Sarret, Philippe; Grignon, Sylvain

    2013-05-01

    Chronic administration of antipsychotics has been associated with dopamine D2 receptor (D2R) upregulation and tardive dyskinesia. We have previously shown that haloperidol, a first-generation antipsychotic (FGA), exerted an increase in D2R expression and oxidative stress and that (±)-α-lipoic acid reversed its effect. Previous studies have implicated the Akt/glycogen synthase kinase-3β (GSK-3β) signaling pathway in antipsychotic action. These findings led us to examine whether the Akt/GSK-3β pathway was involved in D2R upregulation and oxidative stress elicited by antipsychotics and, in (±)-α-lipoic acid-induced reversal of these phenomena, in SH-SY5Y cells. Antipsychotics increased phosphorylation of Akt and GSK-3β, and additive effects were observed with (±)-α-lipoic acid. GSK-3β inhibitors reversed haloperidol-induced overexpression of D2R mRNA levels but did not affect haloperidol-induced oxidative stress. Sustained antipsychotic treatment increased β-arrestin-2 and D2R receptor interaction. Regarding Akt/GSK-3β downstream targets, antipsychotics increased β-catenin levels, whereas (±)-α-lipoic acid induced an elevation of mTOR activation. These results suggest (1) that the effect of antipsychotics on the Akt/GSK-3β pathway in SH-SY5Y cells is reminiscent of their in vivo action, (2) that (±)-α-lipoic acid partially synergizes with antipsychotic drugs (APDs) on the same pathway, and (3) that the Akt/GSK-3β signaling cascade is not involved in the preventive effect of (±)-α-lipoic acid on antipsychotics-induced D2R upregulation.

  8. The Fibroblast Growth Factor signaling pathway

    PubMed Central

    Ornitz, David M; Itoh, Nobuyuki

    2015-01-01

    The signaling component of the mammalian Fibroblast Growth Factor (FGF) family is comprised of eighteen secreted proteins that interact with four signaling tyrosine kinase FGF receptors (FGFRs). Interaction of FGF ligands with their signaling receptors is regulated by protein or proteoglycan cofactors and by extracellular binding proteins. Activated FGFRs phosphorylate specific tyrosine residues that mediate interaction with cytosolic adaptor proteins and the RAS-MAPK, PI3K-AKT, PLCγ, and STAT intracellular signaling pathways. Four structurally related intracellular non-signaling FGFs interact with and regulate the family of voltage gated sodium channels. Members of the FGF family function in the earliest stages of embryonic development and during organogenesis to maintain progenitor cells and mediate their growth, differentiation, survival, and patterning. FGFs also have roles in adult tissues where they mediate metabolic functions, tissue repair, and regeneration, often by reactivating developmental signaling pathways. Consistent with the presence of FGFs in almost all tissues and organs, aberrant activity of the pathway is associated with developmental defects that disrupt organogenesis, impair the response to injury, and result in metabolic disorders, and cancer. © 2015 Wiley Periodicals, Inc. PMID:25772309

  9. GA signalling and cross-talk with other signalling pathways.

    PubMed

    Lor, Vai S; Olszewski, Neil E

    2015-01-01

    Gibberellins (GAs) are phytohormones that regulate growth and development. DELLA proteins repress GA responses. GA binding to its receptor triggers a series of events that culminate in the destruction of DELLA proteins by the 26S proteasome, which removes the repression of GA signalling. DELLA proteins are transcription co-activators that induce the expression of genes which encode products that inhibit GA responses. In addition to repressing GA responses, DELLA proteins influence the activity of other signalling pathways and serve as a central hub from which other pathways influence GA signalling. In this role, DELLA proteins bind to and inhibit proteins, including transcription factors that act in the signalling pathways of other hormones and light. The binding of these proteins to DELLA proteins also inhibits DELLA activity. GA signalling is subject to homoeostatic regulation through GA-induced repression of GA biosynthesis gene expression, and increased production of the GA receptor and enzymes that catabolize bioactive GAs. This review also discusses the nature of mutant DELLA alleles that are used to produce high-yielding 'Green Revolution' cereal varieties, and highlights important gaps in our knowledge of GA signalling. PMID:26374886

  10. β-Hydroxybutyric acid inhibits growth hormone-releasing hormone synthesis and secretion through the GPR109A/extracellular signal-regulated 1/2 signalling pathway in the hypothalamus.

    PubMed

    Fu, S-P; Liu, B-R; Wang, J-F; Xue, W-J; Liu, H-M; Zeng, Y-L; Huang, B-X; Li, S-N; Lv, Q-K; Wang, W; Liu, J-X

    2015-03-01

    β-Hydroxybutyric acid (BHBA) has recently been shown to regulate hormone synthesis and secretion in the hypothalamus. However, little is known about the effects of BHBA-mediated hormone regulation or the detailed mechanisms by which BHBA regulates growth hormone-releasing hormone (GHRH) synthesis and secretion. In the present study, we examined the expression of the BHBA receptor GPR109A in primary hypothalamic cell cultures. We hypothesised that BHBA regulates GHRH via GPR109A and its downstream signals. Initial in vivo studies conducted in rats demonstrated that GHRH mRNA expression in the hypothalamus was strongly inversely correlated with BHBA levels in the cerebrospinal fluid during postnatal development (r = -0.89, P < 0.01). Furthermore, i.c.v. administration of BHBA acutely decreased GHRH mRNA expression in rats. Further in vitro studies revealed a decrease in GHRH synthesis and secretion in primary hypothalamic cells after treatment with BHBA; this effect was inhibited when hypothalamic cells were pretreated with pertussis toxin (PTX). BHBA had no effect on GHRH synthesis and secretion in GT1-7 cells, which do not exhibit cell surface expression of GPR109A. Furthermore, BHBA acutely decreased the transcription of the homeobox gene for Gsh-1 in the hypothalamus in both in vivo and in vitro, and this effect was also inhibited by PTX in vitro. In primary hypothalamic cells, BHBA activated the extracellular signal-regulated kinase (ERK)1/2, p38 and c-Jun N-terminal kinase mitogen-activated protein kinase (MAPK) kinases, as shown by western blot analysis. Moreover, inhibition of ERK1/2 with U0126 attenuated the BHBA-mediated reduction in Gsh-1 expression and GHRH synthesis and secretion. These results strongly suggest that BHBA directly regulates GHRH synthesis and secretion via the GPR109A/ERK1/2 MAPK pathway, and also that Gsh-1 is essential for this function.

  11. Targeting RTK Signaling Pathways in Cancer

    PubMed Central

    Regad, Tarik

    2015-01-01

    The RAS/MAP kinase and the RAS/PI3K/AKT pathways play a key role in the regulation of proliferation, differentiation and survival. The induction of these pathways depends on Receptor Tyrosine Kinases (RTKs) that are activated upon ligand binding. In cancer, constitutive and aberrant activations of components of those pathways result in increased proliferation, survival and metastasis. For instance, mutations affecting RTKs, Ras, B-Raf, PI3K and AKT are common in perpetuating the malignancy of several types of cancers and from different tissue origins. Therefore, these signaling pathways became prime targets for cancer therapy. This review aims to provide an overview about the most frequently encountered mutations, the pathogenesis that results from such mutations and the known therapeutic strategies developed to counteract their aberrant functions. PMID:26404379

  12. The Fog signaling pathway: Insights into signaling in morphogenesis

    PubMed Central

    Manning, Alyssa J.; Rogers, Stephen L.

    2014-01-01

    Epithelia form the building blocks of many tissue and organ types. Epithelial cells often form a contiguous 2-dimensional sheet that is held together by strong adhesions. The mechanical properties conferred by these adhesions allow the cells to undergo dramatic three-dimensional morphogenetic movements while maintaining cell–cell contacts during embryogenesis and post-embryonic development. The Drosophila Folded gastrulation pathway triggers epithelial cell shape changes that drive gastrulation and tissue folding and is one of the most extensively studied examples of epithelial morphogenesis. This pathway has yielded key insights into the signaling mechanisms and cellular machinery involved in epithelial remodeling. In this review, we discuss principles of morphogenesis and signaling that have been discovered through genetic and cell biological examination of this pathway. We also consider various regulatory mechanisms and the system's relevance to mammalian development. We propose future directions that will continue to broaden our knowledge of morphogenesis across taxa. PMID:25127992

  13. Inhibitory effects of omega-3 fatty acids on early brain injury after subarachnoid hemorrhage in rats: Possible involvement of G protein-coupled receptor 120/β-arrestin2/TGF-β activated kinase-1 binding protein-1 signaling pathway.

    PubMed

    Yin, Jia; Li, Haiying; Meng, Chengjie; Chen, Dongdong; Chen, Zhouqing; Wang, Yibin; Wang, Zhong; Chen, Gang

    2016-06-01

    Omega-3 fatty acids have been reported to improve neuron functions during aging and in patients affected by mild cognitive impairment, and mediate potent anti-inflammatory via G protein-coupled receptor 120 (GPR120) signal pathway. Neuron dysfunction and inflammatory response also contributed to the progression of subarachnoid hemorrhage (SAH)-induced early brain injury (EBI). This study was to examine the effects of omega-3 fatty acids on SAH-induced EBI. Two weeks before SAH, 30% Omega-3 fatty acids was administered by oral gavage at 1g/kg body weight once every 24h. Specific siRNA for GPR120 was exploited. Terminal deoxynucleotidyl transferase dUTP nick end labeling, fluoro-Jade B staining, and neurobehavioral scores and brain water content test showed that omega-3 fatty acids effectively suppressed SAH-induced brain cell apoptosis and neuronal degradation, behavioral impairment, and brain edema. Western blot, immunoprecipitation, and electrophoretic mobility shift assays results showed that omega-3 fatty acids effectively suppressed SAH-induced elevation of inflammatory factors, including cyclooxygenase-2, monocyte chemoattractant protein-1, and inducible nitric oxide synthase. In addition, omega-3 fatty acids could inhibit phosphorylation of transforming growth factor β activated kinase-1 (TAK1), MEK4, c-Jun N-terminal kinase, and IkappaB kinase as well as activation of nuclear factor kappa B through regulating GPR120/β-arrestin2/TAK1 binding protein-1 pathway. Furthermore, siRNA-induced GPR120 silencing blocked the protective effects of omega-3 fatty acids. Here, we show that stimulation of GPR120 with omega-3 fatty acids pretreatment causes anti-apoptosis and anti-inflammatory effects via β-arrestin2/TAK1 binding protein-1/TAK1 pathway in the brains of SAH rats. Fish omega-3 fatty acids as part of a daily diet may reduce EBI in an experimental rat model of SAH.

  14. Inhibitory effects of omega-3 fatty acids on early brain injury after subarachnoid hemorrhage in rats: Possible involvement of G protein-coupled receptor 120/β-arrestin2/TGF-β activated kinase-1 binding protein-1 signaling pathway.

    PubMed

    Yin, Jia; Li, Haiying; Meng, Chengjie; Chen, Dongdong; Chen, Zhouqing; Wang, Yibin; Wang, Zhong; Chen, Gang

    2016-06-01

    Omega-3 fatty acids have been reported to improve neuron functions during aging and in patients affected by mild cognitive impairment, and mediate potent anti-inflammatory via G protein-coupled receptor 120 (GPR120) signal pathway. Neuron dysfunction and inflammatory response also contributed to the progression of subarachnoid hemorrhage (SAH)-induced early brain injury (EBI). This study was to examine the effects of omega-3 fatty acids on SAH-induced EBI. Two weeks before SAH, 30% Omega-3 fatty acids was administered by oral gavage at 1g/kg body weight once every 24h. Specific siRNA for GPR120 was exploited. Terminal deoxynucleotidyl transferase dUTP nick end labeling, fluoro-Jade B staining, and neurobehavioral scores and brain water content test showed that omega-3 fatty acids effectively suppressed SAH-induced brain cell apoptosis and neuronal degradation, behavioral impairment, and brain edema. Western blot, immunoprecipitation, and electrophoretic mobility shift assays results showed that omega-3 fatty acids effectively suppressed SAH-induced elevation of inflammatory factors, including cyclooxygenase-2, monocyte chemoattractant protein-1, and inducible nitric oxide synthase. In addition, omega-3 fatty acids could inhibit phosphorylation of transforming growth factor β activated kinase-1 (TAK1), MEK4, c-Jun N-terminal kinase, and IkappaB kinase as well as activation of nuclear factor kappa B through regulating GPR120/β-arrestin2/TAK1 binding protein-1 pathway. Furthermore, siRNA-induced GPR120 silencing blocked the protective effects of omega-3 fatty acids. Here, we show that stimulation of GPR120 with omega-3 fatty acids pretreatment causes anti-apoptosis and anti-inflammatory effects via β-arrestin2/TAK1 binding protein-1/TAK1 pathway in the brains of SAH rats. Fish omega-3 fatty acids as part of a daily diet may reduce EBI in an experimental rat model of SAH. PMID:27000704

  15. Antiepileptic Effect of Uncaria rhynchophylla and Rhynchophylline Involved in the Initiation of c-Jun N-Terminal Kinase Phosphorylation of MAPK Signal Pathways in Acute Seizures of Kainic Acid-Treated Rats.

    PubMed

    Hsu, Hsin-Cheng; Tang, Nou-Ying; Liu, Chung-Hsiang; Hsieh, Ching-Liang

    2013-01-01

    Seizures cause inflammation of the central nervous system. The extent of the inflammation is related to the severity and recurrence of the seizures. Cell surface receptors are stimulated by stimulators such as kainic acid (KA), which causes intracellular mitogen-activated protein kinase (MAPK) signal pathway transmission to coordinate a response. It is known that Uncaria rhynchophylla (UR) and rhynchophylline (RP) have anticonvulsive effects, although the mechanisms remain unclear. Therefore, the purpose of this study is to develop a novel strategy for treating epilepsy by investigating how UR and RP initiate their anticonvulsive mechanisms. Sprague-Dawley rats were administered KA (12 mg/kg, i.p.) to induce seizure before being sacrificed. The brain was removed 3 h after KA administration. The results indicate that pretreatment with UR (1.0 g/kg), RP (0.25 mg/kg), and valproic acid (VA, 250 mg/kg) for 3 d could reduce epileptic seizures and could also reduce the expression of c-Jun aminoterminal kinase phosphorylation (JNKp) of MAPK signal pathways in the cerebral cortex and hippocampus brain tissues. Proinflammatory cytokines interleukin (IL)-1 β , IL-6, and tumor necrosis factor- α remain unchanged, indicating that the anticonvulsive effect of UR and RP is initially involved in the JNKp MAPK signal pathway during the KA-induced acute seizure period. PMID:24381640

  16. Environmentally relevant concentrations of arsenite and monomethylarsonous acid inhibit IL-7/STAT5 cytokine signaling pathways in mouse CD3+CD4-CD8- double negative thymus cells.

    PubMed

    Xu, Huan; Lauer, Fredine T; Liu, Ke Jian; Hudson, Laurie G; Burchiel, Scott W

    2016-04-15

    Environmental arsenic exposure is a public health issue. Immunotoxicity induced by arsenic has been reported in humans and animal models. The purpose of this study was to evaluate mechanisms of As(+3) and MMA(+3) toxicity in mouse thymus cells. Because we know that MMA(+3) inhibits IL-7 signaling in mouse bone marrow pre-B cells, we studied the influence of As(+3) and MMA(+3) on T cell development in the thymus at the earliest stage of T cell development (CD4-CD8-, double negative, DN) which requires IL-7 dependent signaling. We found in a DN thymus cell line (D1) that a low concentration of MMA(+3) (50 nM) suppressed IL-7 dependent JAK1, 3 and STAT5 signaling. As(+3) suppressed STAT5 and JAK3 at higher concentrations (500 nM). Cell surface expression of the IL-7 receptor (CD127) was also suppressed by 50 nM MMA(+)3, but was increased by 500 NM As(+3), indicating possible differences in the mechanisms of action of these agents. A decrease in cyclin D1 protein expression was observed in D1 cells exposed to As(+3) at 500 nM and MMA(+3) starting at 50 nM, suggesting that arsenic at these environmentally-relevant doses suppresses early T cell development through the inhibition of IL-7 signaling pathway. PMID:26921788

  17. Environmentally relevant concentrations of arsenite and monomethylarsonous acid inhibit IL-7/STAT5 cytokine signaling pathways in mouse CD3+CD4-CD8- double negative thymus cells.

    PubMed

    Xu, Huan; Lauer, Fredine T; Liu, Ke Jian; Hudson, Laurie G; Burchiel, Scott W

    2016-04-15

    Environmental arsenic exposure is a public health issue. Immunotoxicity induced by arsenic has been reported in humans and animal models. The purpose of this study was to evaluate mechanisms of As(+3) and MMA(+3) toxicity in mouse thymus cells. Because we know that MMA(+3) inhibits IL-7 signaling in mouse bone marrow pre-B cells, we studied the influence of As(+3) and MMA(+3) on T cell development in the thymus at the earliest stage of T cell development (CD4-CD8-, double negative, DN) which requires IL-7 dependent signaling. We found in a DN thymus cell line (D1) that a low concentration of MMA(+3) (50 nM) suppressed IL-7 dependent JAK1, 3 and STAT5 signaling. As(+3) suppressed STAT5 and JAK3 at higher concentrations (500 nM). Cell surface expression of the IL-7 receptor (CD127) was also suppressed by 50 nM MMA(+)3, but was increased by 500 NM As(+3), indicating possible differences in the mechanisms of action of these agents. A decrease in cyclin D1 protein expression was observed in D1 cells exposed to As(+3) at 500 nM and MMA(+3) starting at 50 nM, suggesting that arsenic at these environmentally-relevant doses suppresses early T cell development through the inhibition of IL-7 signaling pathway.

  18. Chlorogenic acid induces apoptosis to inhibit inflammatory proliferation of IL-6-induced fibroblast-like synoviocytes through modulating the activation of JAK/STAT and NF-κB signaling pathways

    PubMed Central

    LOU, LIXIA; ZHOU, JINGWEI; LIU, YUJUN; WEI, YI; ZHAO, JIULI; DENG, JIAGANG; DONG, BIN; ZHU, LINGQUN; WU, AIMING; YANG, YINGXI; CHAI, LIMIN

    2016-01-01

    Chlorogenic acid (CGA) is the primary constituent of Caulis Lonicerae, a Chinese herb used for the treatment of rheumatoid arthritis (RA). The present study aimed to investigate whether CGA was able to inhibit the proliferation of the fibroblast-like synoviocyte cell line (RSC-364), stimulated by interleukin (IL)-6, through inducing apoptosis. Following incubation with IL-6 or IL-6 and CGA, the cellular proliferation of RSC-364 cells was detected by MTT assay. The ratio of apoptosed cells were detected by flow cytometry. Western blot analysis was performed to observe protein expression levels of key molecules involved in the Janus-activated kinase/signal transducer and activator of transcription 3 (JAK/STAT) signaling pathway [phosphorylated (p)-STAT3, JAK1 and gp130] and the nuclear factor κB (NF-κB) signaling pathway [phosphorylated (p)-inhibitor of κB kinase subunit α/β and NF-κB p50). It was revealed that CGA was able to inhibit the inflammatory proliferation of RSC-364 cells mediated by IL-6 through inducing apoptosis. CGA was also able to suppress the expression levels of key molecules in the JAK/STAT and NF-κB signaling pathways, and inhibit the activation of these signaling pathways in the inflammatory response through IL-6-mediated signaling, thereby resulting in the inhibition of the inflammatory proliferation of synoviocytes. The present results indicated that CGA may have potential as a novel therapeutic agent for inhibiting inflammatory hyperplasia of the synovium through inducing synoviocyte apoptosis in patients with RA. PMID:27168850

  19. Gallic acid, a phenolic compound, exerts anti-angiogenic effects via the PTEN/AKT/HIF-1α/VEGF signaling pathway in ovarian cancer cells.

    PubMed

    He, Zhiping; Chen, Allen Y; Rojanasakul, Yon; Rankin, Gary O; Chen, Yi Charlie

    2016-01-01

    Gallic acid (GA), a polyphenol, is widely found in numerous fruits and vegetables, particularly in hickory nuts. In the present study, we found that gallic acid, a natural phenolic compound isolated from fruits and vegetables, had a more potent growth inhibitory effect on two ovarian cancer cell lines, OVCAR-3 and A2780/CP70, than the effect on a normal ovarian cell line, IOSE-364. These results demonstrated that GA selectively inhibits the growth of cancer cells. Gene expression was examined by ELISA and western blot analysis, and gene pathways were examined by luciferase assay. It was found that GA inhibited VEGF secretion and suppressed in vitro angiogenesis in a concentration-dependent manner. GA downregulated AKT phosphorylation as well as HIF-1α expression but promoted PTEN expression. The luciferase assay results suggest that the PTEN/AKT/HIF-1α pathway accounts for the inhibitory effect of GA on VEGF expression and in vitro angiogenesis. These findings provide strong support for the high potential of GA in the prevention and therapy of ovarian cancer.

  20. Gallic acid, a phenolic compound, exerts anti-angiogenic effects via the PTEN/AKT/HIF-1α/VEGF signaling pathway in ovarian cancer cells

    PubMed Central

    HE, ZHIPING; CHEN, ALLEN Y.; ROJANASAKUL, YON; RANKIN, GARY O.; CHEN, YI CHARLIE

    2016-01-01

    Gallic acid (GA), a polyphenol, is widely found in numerous fruits and vegetables, particularly in hickory nuts. In the present study, we found that gallic acid, a natural phenolic compound isolated from fruits and vegetables, had a more potent growth inhibitory effect on two ovarian cancer cell lines, OVCAR-3 and A2780/CP70, than the effect on a normal ovarian cell line, IOSE-364. These results demonstrated that GA selectively inhibits the growth of cancer cells. Gene expression was examined by ELISA and western blot analysis, and gene pathways were examined by luciferase assay. It was found that GA inhibited VEGF secretion and suppressed in vitro angiogenesis in a concentration-dependent manner. GA downregulated AKT phosphorylation as well as HIF-1α expression but promoted PTEN expression. The luciferase assay results suggest that the PTEN/AKT/HIF-1α pathway accounts for the inhibitory effect of GA on VEGF expression and in vitro angiogenesis. These findings provide strong support for the high potential of GA in the prevention and therapy of ovarian cancer. PMID:26530725

  1. The ethylene signal transduction pathway in Arabidopsis

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  2. Lysophosphatidic acid signalling in development.

    PubMed

    Sheng, Xiaoyan; Yung, Yun C; Chen, Allison; Chun, Jerold

    2015-04-15

    Lysophosphatidic acid (LPA) is a bioactive phospholipid that is present in all tissues examined to date. LPA signals extracellularly via cognate G protein-coupled receptors to mediate cellular processes such as survival, proliferation, differentiation, migration, adhesion and morphology. These LPA-influenced processes impact many aspects of organismal development. In particular, LPA signalling has been shown to affect fertility and reproduction, formation of the nervous system, and development of the vasculature. Here and in the accompanying poster, we review the developmentally related features of LPA signalling. PMID:25852197

  3. Eicosapentaenoic acid membrane incorporation impairs ABCA1-dependent cholesterol efflux via a protein kinase A signaling pathway in primary human macrophages.

    PubMed

    Fournier, Natalie; Tardivel, Sylviane; Benoist, Jean-François; Vedie, Benoît; Rousseau-Ralliard, Delphine; Nowak, Maxime; Allaoui, Fatima; Paul, Jean-Louis

    2016-04-01

    A diet rich in n-3/n-6 polyunsaturated fatty acids (PUFAs) is cardioprotective. Dietary PUFAs affect the cellular phospholipids composition, which may influence the function of membrane proteins. We investigated the impact of the membrane incorporation of several PUFAs on ABCA1-mediated cholesterol efflux, a key antiatherogenic pathway. Arachidonic acid (AA) (C20:4 n-6) and docosahexaenoic acid (DHA) (C22:6 n-3) decreased or increased cholesterol efflux from J774 mouse macrophages, respectively, whereas they had no effect on efflux from human monocyte-derived macrophages (HMDM). Importantly, eicosapentaenoic acid (EPA) (C20:5 n-3) induced a dose-dependent reduction of ABCA1 functionality in both cellular models (-28% for 70μM of EPA in HMDM), without any alterations in ABCA1 expression. These results show that PUFA membrane incorporation does not have the same consequences on cholesterol efflux from mouse and human macrophages. The EPA-treated HMDM exhibited strong phospholipid composition changes, with high levels of both EPA and its elongation product docosapentaenoic acid (DPA) (C22:5 n-3), which is associated with a decreased level of AA. In HMDM, EPA reduced the ATPase activity of the membrane transporter. Moreover, the activation of adenylate cyclase by forskolin and the inhibition of cAMP phosphodiesterase by isobutylmethylxanthine restored ABCA1 cholesterol efflux in EPA-treated human macrophages. In conclusion, EPA membrane incorporation reduces ABCA1 functionality in mouse macrophages as well as in primary human macrophages and this effect seems to be PKA-dependent in human macrophages.

  4. Purinergic signaling pathways in endocrine system.

    PubMed

    Bjelobaba, Ivana; Janjic, Marija M; Stojilkovic, Stanko S

    2015-09-01

    Adenosine-5'-triphosphate is released by neuroendocrine, endocrine, and other cell types and acts as an extracellular agonist for ligand-gated P2X cationic channels and G protein-coupled P2Y receptors in numerous organs and tissues, including the endocrine system. The breakdown of ATP by ectonucleotidases not only terminates its extracellular messenger functions, but also provides a pathway for the generation of two additional agonists: adenosine 5'-diphosphate, acting via some P2Y receptors, and adenosine, a native agonist for G protein-coupled adenosine receptors, also expressed in the endocrine system. This article provides a review of purinergic signaling pathways in the hypothalamic magnocellular neurosecretory cells and neurohypophysis, hypothalamic parvocellular neuroendocrine system, adenohypophysis, and effector glands organized in five axes: hypothalamic-pituitary-gonadal, hypothalamic-pituitary-thyroid, hypothalamic-pituitary-adrenal, hypothalamic-pituitary-growth hormone, and hypothalamic-pituitary-prolactin. We attempted to summarize current knowledge of purinergic receptor subtypes expressed in the endocrine system, including their roles in intracellular signaling, hormone secretion, and other cell functions. We also briefly review the release mechanism for adenosine-5'-triphosphate by neuroendocrine, endocrine and surrounding cells, the enzymes involved in adenosine-5'-triphosphate hydrolysis to adenosine-5'-diphosphate and adenosine, and the relevance of this pathway for sequential activation of receptors and termination of signaling.

  5. Purinergic Signaling Pathways in Endocrine System

    PubMed Central

    Bjelobaba, Ivana; Janjic, Marija M.; Stojilkovic, Stanko S.

    2015-01-01

    Adenosine-5′-triphosphate is released by neuroendocrine, endocrine, and other cell types and acts as an extracellular agonist for ligand-gated P2X cationic channels and G protein-coupled P2Y receptors in numerous organs and tissues, including the endocrine system. The breakdown of ATP by ectonucleotidases not only terminates its extracellular messenger functions, but also provides a pathway for the generation of two additional agonists: adenosine 5′-diphosphate, acting via some P2Y receptors, and adenosine, a native agonist for G protein-coupled adenosine receptors, also expressed in the endocrine system. This article provides a review of purinergic signaling pathways in the hypothalamic magnocellular neurosecretory cells and neurohypophysis, hypothalamic parvocellular neuroendocrine system, adenohypophysis, and effector glands organized in five axes: hypothalamic-pituitary-gonadal, hypothalamic-pituitary-thyroid, hypothalamic-pituitary-adrenal, hypothalamic-pituitary-growth hormone, and hypothalamic-pituitary-prolactin. We attempted to summarize current knowledge of purinergic receptor subtypes expressed in the endocrine system, including their roles in intracellular signaling, hormone secretion, and other cell functions. We also briefly review the release mechanism for adenosine-5′-triphosphate by neuroendocrine, endocrine and surrounding cells, the enzymes involved in adenosine-5′-triphosphate hydrolysis to adenosine-5′-diphosphate and adenosine, and the relevance of this pathway for sequential activation of receptors and termination of signaling. PMID:25960051

  6. Cytochrome P450 epoxygenase pathway of polyunsaturated fatty acid metabolism

    PubMed Central

    Spector, Arthur A.; Kim, Hee-Yong

    2014-01-01

    Polyunsaturated fatty acids (PUFA) are oxidized by cytochrome P450 epoxygenases to PUFA epoxides which function as potent lipid mediators. The major metabolic pathways of PUFA epoxides are incorporation into phospholipids and hydrolysis to the corresponding PUFA diols by soluble epoxide hydrolase. Inhibitors of soluble epoxide hydrolase stabilize PUFA epoxides and potentiate their functional effects. The epoxyeicosatrienoic acids (EETs) synthesized from arachidonic acid produce vasodilation, stimulate angiogenesis, have anti-inflammatory actions, and protect the heart against ischemia-reperfusion injury. EETs produce these functional effects by activating receptor-mediated signaling pathways and ion channels. The epoxyeicosatetraenoic acids synthesized from eicosapentaenoic acid and epoxydocosapentaenoic acids synthesized from docosahexaenoic acid are potent inhibitors of cardiac arrhythmias. Epoxydocosapentaenoic acids also inhibit angiogenesis, decrease inflammatory and neuropathic pain, and reduce tumor metastasis. These findings indicate that a number of the beneficial functions of PUFA may be due to their conversion to PUFA epoxides. PMID:25093613

  7. Phylogenetic diversity of stress signalling pathways in fungi

    PubMed Central

    Nikolaou, Elissavet; Agrafioti, Ino; Stumpf, Michael; Quinn, Janet; Stansfield, Ian; Brown, Alistair JP

    2009-01-01

    Background Microbes must sense environmental stresses, transduce these signals and mount protective responses to survive in hostile environments. In this study we have tested the hypothesis that fungal stress signalling pathways have evolved rapidly in a niche-specific fashion that is independent of phylogeny. To test this hypothesis we have compared the conservation of stress signalling molecules in diverse fungal species with their stress resistance. These fungi, which include ascomycetes, basidiomycetes and microsporidia, occupy highly divergent niches from saline environments to plant or mammalian hosts. Results The fungi displayed significant variation in their resistance to osmotic (NaCl and sorbitol), oxidative (H2O2 and menadione) and cell wall stresses (Calcofluor White and Congo Red). There was no strict correlation between fungal phylogeny and stress resistance. Rather, the human pathogens tended to be more resistant to all three types of stress, an exception being the sensitivity of Candida albicans to the cell wall stress, Calcofluor White. In contrast, the plant pathogens were relatively sensitive to oxidative stress. The degree of conservation of osmotic, oxidative and cell wall stress signalling pathways amongst the eighteen fungal species was examined. Putative orthologues of functionally defined signalling components in Saccharomyces cerevisiae were identified by performing reciprocal BLASTP searches, and the percent amino acid identities of these orthologues recorded. This revealed that in general, central components of the osmotic, oxidative and cell wall stress signalling pathways are relatively well conserved, whereas the sensors lying upstream and transcriptional regulators lying downstream of these modules have diverged significantly. There was no obvious correlation between the degree of conservation of stress signalling pathways and the resistance of a particular fungus to the corresponding stress. Conclusion Our data are consistent with

  8. Signaling Pathways in Leiomyoma: Understanding Pathobiology and Implications for Therapy

    PubMed Central

    Borahay, Mostafa A; Al-Hendy, Ayman; Kilic, Gokhan S; Boehning, Darren

    2015-01-01

    Uterine leiomyomas are the most common tumors of the female genital tract, affecting 50% to 70% of females by the age of 50. Despite their prevalence and enormous medical and economic impact, no effective medical treatment is currently available. This is, in part, due to the poor understanding of their underlying pathobiology. Although they are thought to start as a clonal proliferation of a single myometrial smooth muscle cell, these early cytogenetic alterations are considered insufficient for tumor development and additional complex signaling pathway alterations are crucial. These include steroids, growth factors, transforming growth factor-beta (TGF-β)/Smad; wingless-type (Wnt)/β-catenin, retinoic acid, vitamin D, and peroxisome proliferator-activated receptor γ (PPARγ). An important finding is that several of these pathways converge in a summative way. For example, mitogen-activated protein kinase (MAPK) and Akt pathways seem to act as signal integrators, incorporating input from several signaling pathways, including growth factors, estrogen and vitamin D. This underlines the multifactorial origin and complex nature of these tumors. In this review, we aim to dissect these pathways and discuss their interconnections, aberrations and role in leiomyoma pathobiology. We also aim to identify potential targets for development of novel therapeutics. PMID:25879625

  9. Fumaric acid esters promote neuronal survival upon ischemic stress through activation of the Nrf2 but not HIF-1 signaling pathway.

    PubMed

    Lin-Holderer, Jiemeng; Li, Lexiao; Gruneberg, Daniel; Marti, Hugo H; Kunze, Reiner

    2016-06-01

    Oxidative stress is a hallmark of ischemic stroke pathogenesis causing neuronal malfunction and cell death. Up-regulation of anti-oxidative genes through activation of the NF-E2-related transcription factor 2 (Nrf2) is one of the key mechanisms in cellular defense against oxidative stress. Fumaric acid esters (FAEs) represent a class of anti-oxidative and anti-inflammatory molecules that are already in clinical use for multiple sclerosis therapy. Purpose of this study was to investigate whether FAEs promote neuronal survival upon ischemia, and analyze putative underlying molecular mechanisms in neurons. Murine organotypic hippocampal slice cultures, and two neuronal cell lines were treated with dimethyl fumarate (DMF) and monomethyl fumarate (MMF). Ischemic conditions were generated by exposing cells and slice cultures to oxygen-glucose deprivation (OGD), and cell death was determined through propidium iodide staining. Treatment with both DMF and MMF immediately after OGD during reoxygenation strongly reduced cell death in hippocampal cultures ex vivo. Both DMF and MMF promoted neuronal survival in HT-22 and SH-SY5Y cell lines exposed to ischemic stress. DMF but not MMF activated the anti-oxidative Nrf2 pathway in neurons. Accordingly, Nrf2 knockdown in murine neurons abrogated the protective effect of DMF but not MMF. Moreover, FAEs did not activate the hypoxia-inducible factor (HIF) pathway suggesting that this pathway may not significantly contribute to FAE mediated neuroprotection. Our results may provide the basis for a new therapeutic approach to treat ischemic pathologies such as stroke with a drug that already has a broad safety record in humans. PMID:26801077

  10. Activation of ATP-sensitive potassium channels in rat pancreatic beta-cells by linoleic acid through both intracellular metabolites and membrane receptor signalling pathway.

    PubMed

    Zhao, Yu-Feng; Pei, Jianming; Chen, Chen

    2008-09-01

    ATP-sensitive potassium channels (K(ATP) channels) determine the excitability of pancreatic beta-cells and importantly regulate glucose-stimulated insulin secretion (GSIS). Long-chain free fatty acids (FFAs) decrease GSIS after long-term exposure to beta-cells, but the effects of exogenous FFAs on K(ATP) channels are not yet well clarified. In this study, the effects of linoleic acid (LA) on membrane potential (MP) and K(ATP) channels were observed in primary cultured rat pancreatic beta-cells. LA (20 microM) induced hyperpolarization of MP and opening of K(ATP) channels, which was totally reversed and inhibited by tolbutamide, a K(ATP) channel blocker. Inhibition of LA metabolism by acyl-CoA synthetase inhibitor, triacsin C (10 microM), partially inhibited LA-induced opening of K(ATP) channels by 64%. The non-FFA G protein-coupled receptor (GPR) 40 agonist, GW9508 (40 microM), induced an opening of K(ATP) channels, which was similar to that induced by LA under triacsin C treatment. Blockade of protein kinases A and C did not influence the opening of K(ATP) channels induced by LA and GW9508, indicating that these two protein kinase pathways are not involved in the action of LA on K(ATP) channels. The present study demonstrates that LA induces hyperpolarization of MP by activating K(ATP) channels via both intracellular metabolites and activation of GPR40. It indicates that not only intracellular metabolites of FFAs but also GPR40-mediated pathways take part in the inhibition of GSIS and beta-cell dysfunction induced by FFAs.

  11. Nongenomic Signaling Pathways of Estrogen Toxicity

    PubMed Central

    Watson, Cheryl S.; Jeng, Yow-Jiun; Kochukov, Mikhail Y.

    2010-01-01

    Xenoestrogens can affect the healthy functioning of a variety of tissues by acting as potent estrogens via nongenomic signaling pathways or by interfering with those actions of multiple physiological estrogens. Collectively, our and other studies have compared a wide range of estrogenic compounds, including some closely structurally related subgroups. The estrogens that have been studied include environmental contaminants of different subclasses, dietary estrogens, and several prominent physiological metabolites. By comparing the nongenomic signaling and functional responses to these compounds, we have begun to address the structural requirements for their actions through membrane estrogen receptors in the pituitary, in comparison to other tissues, and to gain insights into their typical non-monotonic dose-response behavior. Their multiple inputs into cellular signaling begin processes that eventually integrate at the level of mitogen-activated protein kinase activities to coordinately regulate broad cellular destinies, such as proliferation, apoptosis, or differentiation. PMID:19955490

  12. α-Lipoic acid protects against the cytotoxicity and oxidative stress induced by cadmium in HepG2 cells through regeneration of glutathione by glutathione reductase via Nrf2/ARE signaling pathway.

    PubMed

    Shi, Chunli; Zhou, Xue; Zhang, Jiayu; Wang, Jiachun; Xie, Hong; Wu, Zhigang

    2016-07-01

    α-Lipoic acid (α-LA) is a potent natural antioxidant, which is capable of regenerating glutathione (GSH). However, the mechanisms by which α-LA regenerates reduced glutathione (rGSH) via the reduction of oxidized glutathione (GSSG) by glutathione reductase (GR) are still not well understood. In the present study, we investigated if α-LA replenished rGSH by GR via Nrf2/ARE signaling pathway in cadmium-treated HepG2 cells. We found that α-LA antagonized the oxidative damage and alleviated the cytotoxicity in cadmium-induced HepG2 cells by regeneration of rGSH. α-LA regenerated rGSH by activating Nrf2 signaling pathway via promoting the nuclear translocation of Nrf2, which upregulates the transcription of GR, and thus increased the activity of GR. Our results indicated that α-LA was an effective agent to antagonize the oxidative stress and alleviate the cytotoxicity in cadmium-treated HepG2 cells by regenerating rGSH through activating Nrf2 signaling pathway.

  13. α-Lipoic acid protects against the cytotoxicity and oxidative stress induced by cadmium in HepG2 cells through regeneration of glutathione by glutathione reductase via Nrf2/ARE signaling pathway.

    PubMed

    Shi, Chunli; Zhou, Xue; Zhang, Jiayu; Wang, Jiachun; Xie, Hong; Wu, Zhigang

    2016-07-01

    α-Lipoic acid (α-LA) is a potent natural antioxidant, which is capable of regenerating glutathione (GSH). However, the mechanisms by which α-LA regenerates reduced glutathione (rGSH) via the reduction of oxidized glutathione (GSSG) by glutathione reductase (GR) are still not well understood. In the present study, we investigated if α-LA replenished rGSH by GR via Nrf2/ARE signaling pathway in cadmium-treated HepG2 cells. We found that α-LA antagonized the oxidative damage and alleviated the cytotoxicity in cadmium-induced HepG2 cells by regeneration of rGSH. α-LA regenerated rGSH by activating Nrf2 signaling pathway via promoting the nuclear translocation of Nrf2, which upregulates the transcription of GR, and thus increased the activity of GR. Our results indicated that α-LA was an effective agent to antagonize the oxidative stress and alleviate the cytotoxicity in cadmium-treated HepG2 cells by regenerating rGSH through activating Nrf2 signaling pathway. PMID:27343752

  14. Nuclear MEK1 Sequesters PPARγ and Bisects MEK1/ERK Signaling: A Non-Canonical Pathway of Retinoic Acid Inhibition of Adipocyte Differentiation

    PubMed Central

    Dave, Sandeep; Nanduri, Ravikanth; Dkhar, Hedwin Kitdorlang; Bhagyaraj, Ella; Rao, Alka; Gupta, Pawan

    2014-01-01

    Uncontrolled adipogenesis and adipocyte proliferation have been connected to human comorbidities. Retinoic acid (RA) is known to inhibit adipocyte differentiation, however the underlying mechanisms have not been adequately understood. This study reports that RA acting as a ligand to RA receptors (RARs and RXRs) is not a sine qua non to the inhibition of adipogenesis. Our intriguing observation of a negative correlation between increased retinoylation and adipogenesis led us to explore retinoylated proteins in adipocytes. Exportin (CRM1) was found to be retinoylated, which in turn can affect the spatio-temporal regulation of the important signaling molecule mitogen-activated protein kinase kinase 1 (MEK1), likely by disrupting its export from the nucleus. Nuclear enrichment of MEK1 physically sequesters peroxisome proliferator-activated receptor gamma (PPARγ), the master regulator of adipogenesis, from its target genes and thus inhibits adipogenesis while also disrupting the MEK1-extracellular-signal regulated kinase (ERK) signaling cascade. This study is first to report the inhibition of adipocyte differentiation by retinoylation. PMID:24959884

  15. Insulin signaling pathways in lepidopteran ecdysone secretion

    PubMed Central

    Smith, Wendy A.; Lamattina, Anthony; Collins, McKensie

    2014-01-01

    Molting and metamorphosis are stimulated by the secretion of ecdysteroid hormones from the prothoracic glands. Insulin-like hormones have been found to enhance prothoracic gland activity, providing a mechanism to link molting to nutritional state. In silk moths (Bombyx mori), the prothoracic glands are directly stimulated by insulin and the insulin-like hormone bombyxin. Further, in Bombyx, the neuropeptide prothoracicotropic hormone (PTTH) appears to act at least in part through the insulin-signaling pathway. In the prothoracic glands of Manduca sexta, while insulin stimulates the phosphorylation of the insulin receptor and Akt, neither insulin nor bombyxin II stimulate ecdysone secretion. Involvement of the insulin-signaling pathway in Manduca prothoracic glands was explored using two inhibitors of phosphatidylinositol-3-kinase (PI3K), LY294002 and wortmannin. PI3K inhibitors block the phosphorylation of Akt and 4EBP but have no effect on ecdysone secretion, or on the phosphorylation of the MAPkinase, ERK. Inhibitors that block phosphorylation of ERK, including the MEK inhibitor U0126, and high doses of the RSK inhibitor SL0101, effectively inhibit ecdysone secretion. The results highlight differences between the two lepidopteran insects most commonly used to directly study ecdysteroid secretion. In Bombyx, the PTTH and insulin-signaling pathways intersect; both insulin and PTTH enhance the phosphorylation of Akt and stimulate ecdysteroid secretion, and inhibition of PI3K reduces ecdysteroid secretion. By contrast, in Manduca, the action of PTTH is distinct from insulin. The results highlight species differences in the roles of translational regulators such as 4EBP, and members of the MAPkinase pathway such as ERK and RSK, in the regulation of insect ecdysone secretion, and in the impact of nutritionally-sensitive hormones such as insulin in the control of ecdysone secretion and molting. PMID:24550835

  16. Subpathway Analysis based on Signaling-Pathway Impact Analysis of Signaling Pathway

    PubMed Central

    Li, Xianbin; Shen, Liangzhong; Shang, Xuequn; Liu, Wenbin

    2015-01-01

    Pathway analysis is a common approach to gain insight from biological experiments. Signaling-pathway impact analysis (SPIA) is one such method and combines both the classical enrichment analysis and the actual perturbation on a given pathway. Because this method focuses on a single pathway, its resolution generally is not very high because the differentially expressed genes may be enriched in a local region of the pathway. In the present work, to identify cancer-related pathways, we incorporated a recent subpathway analysis method into the SPIA method to form the “sub-SPIA method.” The original subpathway analysis uses the k-clique structure to define a subpathway. However, it is not sufficiently flexible to capture subpathways with complex structure and usually results in many overlapping subpathways. We therefore propose using the minimal-spanning-tree structure to find a subpathway. We apply this approach to colorectal cancer and lung cancer datasets, and our results show that sub-SPIA can identify many significant pathways associated with each specific cancer that other methods miss. Based on the entire pathway network in the Kyoto Encyclopedia of Genes and Genomes, we find that the pathways identified by sub-SPIA not only have the largest average degree, but also are more closely connected than those identified by other methods. This result suggests that the abnormality signal propagating through them might be responsible for the specific cancer or disease. PMID:26207919

  17. The platelet-activating factor acetylhydrolase gene derived from Trichoderma harzianum induces maize resistance to Curvularia lunata through the jasmonic acid signaling pathway.

    PubMed

    Yu, Chuanjin; Fan, Lili; Gao, Jinxin; Wang, Meng; Wu, Qiong; Tang, Jun; Li, Yaqian; Chen, Jie

    2015-01-01

    Platelet-activating factor acetylhydrolase (PAF-AH) derived from Trichoderma harzianum was upregulated by the interaction of T. harzianum with maize roots or the foliar pathogen Curvularia lunata. PAF-AH was associated with chitinase and cellulase expressions, but especially with chitinase, because its activity in the KO40 transformant (PAF-AH disruption transformant) was lower, compared with the wild-type strain T28. The result demonstrated that the colonization of maize roots by T. harzianum induced systemic protection of leaves inoculated with C. lunata. Such protection was associated with the expression of inducible jasmonic acid pathway-related genes. Moreover, the data from liquid chromatography-mass spectrometry confirmed that the concentration of jasmonic acid in maize leaves was associated with the expression level of defense-related genes, suggesting that PAF-AH induced resistance to the foliar pathogen. Our findings showed that PAF-AH had an important function in inducing systemic resistance to maize leaf spot pathogen. PMID:26273755

  18. The platelet-activating factor acetylhydrolase gene derived from Trichoderma harzianum induces maize resistance to Curvularia lunata through the jasmonic acid signaling pathway.

    PubMed

    Yu, Chuanjin; Fan, Lili; Gao, Jinxin; Wang, Meng; Wu, Qiong; Tang, Jun; Li, Yaqian; Chen, Jie

    2015-01-01

    Platelet-activating factor acetylhydrolase (PAF-AH) derived from Trichoderma harzianum was upregulated by the interaction of T. harzianum with maize roots or the foliar pathogen Curvularia lunata. PAF-AH was associated with chitinase and cellulase expressions, but especially with chitinase, because its activity in the KO40 transformant (PAF-AH disruption transformant) was lower, compared with the wild-type strain T28. The result demonstrated that the colonization of maize roots by T. harzianum induced systemic protection of leaves inoculated with C. lunata. Such protection was associated with the expression of inducible jasmonic acid pathway-related genes. Moreover, the data from liquid chromatography-mass spectrometry confirmed that the concentration of jasmonic acid in maize leaves was associated with the expression level of defense-related genes, suggesting that PAF-AH induced resistance to the foliar pathogen. Our findings showed that PAF-AH had an important function in inducing systemic resistance to maize leaf spot pathogen.

  19. Abscisic acid: biosynthesis, inactivation, homoeostasis and signalling.

    PubMed

    Dong, Ting; Park, Youngmin; Hwang, Inhwan

    2015-01-01

    The phytohormone abscisic acid (ABA) plays crucial roles in numerous physiological processes during plant growth and abiotic stress responses. The endogenous ABA level is controlled by complex regulatory mechanisms involving biosynthesis, catabolism, transport and signal transduction pathways. This complex regulatory network may target multiple levels, including transcription, translation and post-translational regulation of genes involved in ABA responses. Most of the genes involved in ABA biosynthesis, catabolism and transport have been characterized. The local ABA concentration is critical for initiating ABA-mediated signalling during plant development and in response to environmental changes. In this chapter we discuss the mechanisms that regulate ABA biosynthesis, catabolism, transport and homoeostasis. We also present the findings of recent research on ABA perception by cellular receptors, and ABA signalling in response to cellular and environmental conditions.

  20. Lysophosphatidic Acid signaling in the nervous system.

    PubMed

    Yung, Yun C; Stoddard, Nicole C; Mirendil, Hope; Chun, Jerold

    2015-02-18

    The brain is composed of many lipids with varied forms that serve not only as structural components but also as essential signaling molecules. Lysophosphatidic acid (LPA) is an important bioactive lipid species that is part of the lysophospholipid (LP) family. LPA is primarily derived from membrane phospholipids and signals through six cognate G protein-coupled receptors (GPCRs), LPA1-6. These receptors are expressed on most cell types within central and peripheral nervous tissues and have been functionally linked to many neural processes and pathways. This Review covers a current understanding of LPA signaling in the nervous system, with particular focus on the relevance of LPA to both physiological and diseased states. PMID:25695267

  1. Nutrient shortage triggers the hexosamine biosynthetic pathway via the GCN2-ATF4 signalling pathway.

    PubMed

    Chaveroux, Cédric; Sarcinelli, Carmen; Barbet, Virginie; Belfeki, Sofiane; Barthelaix, Audrey; Ferraro-Peyret, Carole; Lebecque, Serge; Renno, Toufic; Bruhat, Alain; Fafournoux, Pierre; Manié, Serge N

    2016-06-03

    The hexosamine biosynthetic pathway (HBP) is a nutrient-sensing metabolic pathway that produces the activated amino sugar UDP-N-acetylglucosamine, a critical substrate for protein glycosylation. Despite its biological significance, little is known about the regulation of HBP flux during nutrient limitation. Here, we report that amino acid or glucose shortage increase GFAT1 production, the first and rate-limiting enzyme of the HBP. GFAT1 is a transcriptional target of the activating transcription factor 4 (ATF4) induced by the GCN2-eIF2α signalling pathway. The increased production of GFAT1 stimulates HBP flux and results in an increase in O-linked β-N-acetylglucosamine protein modifications. Taken together, these findings demonstrate that ATF4 provides a link between nutritional stress and the HBP for the regulation of the O-GlcNAcylation-dependent cellular signalling.

  2. Nutrient shortage triggers the hexosamine biosynthetic pathway via the GCN2-ATF4 signalling pathway

    PubMed Central

    Chaveroux, Cédric; Sarcinelli, Carmen; Barbet, Virginie; Belfeki, Sofiane; Barthelaix, Audrey; Ferraro-Peyret, Carole; Lebecque, Serge; Renno, Toufic; Bruhat, Alain; Fafournoux, Pierre; Manié, Serge N.

    2016-01-01

    The hexosamine biosynthetic pathway (HBP) is a nutrient-sensing metabolic pathway that produces the activated amino sugar UDP-N-acetylglucosamine, a critical substrate for protein glycosylation. Despite its biological significance, little is known about the regulation of HBP flux during nutrient limitation. Here, we report that amino acid or glucose shortage increase GFAT1 production, the first and rate-limiting enzyme of the HBP. GFAT1 is a transcriptional target of the activating transcription factor 4 (ATF4) induced by the GCN2-eIF2α signalling pathway. The increased production of GFAT1 stimulates HBP flux and results in an increase in O-linked β-N-acetylglucosamine protein modifications. Taken together, these findings demonstrate that ATF4 provides a link between nutritional stress and the HBP for the regulation of the O-GlcNAcylation-dependent cellular signalling. PMID:27255611

  3. The immune signaling pathways of Manduca sexta.

    PubMed

    Cao, Xiaolong; He, Yan; Hu, Yingxia; Wang, Yang; Chen, Yun-Ru; Bryant, Bart; Clem, Rollie J; Schwartz, Lawrence M; Blissard, Gary; Jiang, Haobo

    2015-07-01

    Signal transduction pathways and their coordination are critically important for proper functioning of animal immune systems. Our knowledge of the constituents of the intracellular signaling network in insects mainly comes from genetic analyses in Drosophila melanogaster. To facilitate future studies of similar systems in the tobacco hornworm and other lepidopteran insects, we have identified and examined the homologous genes in the genome of Manduca sexta. Based on 1:1 orthologous relationships in most cases, we hypothesize that the Toll, Imd, MAPK-JNK-p38 and JAK-STAT pathways are intact and operative in this species, as are most of the regulatory mechanisms. Similarly, cellular processes such as autophagy, apoptosis and RNA interference probably function in similar ways, because their mediators and modulators are mostly conserved in this lepidopteran species. We have annotated a total of 186 genes encoding 199 proteins, studied their domain structures and evolution, and examined their mRNA levels in tissues at different life stages. Such information provides a genomic perspective of the intricate signaling system in a non-drosophiline insect. PMID:25858029

  4. Schistosoma mansoni: TGF-β Signaling Pathways

    PubMed Central

    LoVerde, Philip T.; Osman, Ahmed; Hinck, Andrew

    2007-01-01

    Schistosome parasites have co-evolved an intricate relationship with their human and snail hosts as well as a novel interplay between the adult male and female parasites. We review the role of the TGF-β signaling pathway in parasite development, host-parasite interactions and male-female interactions. The data to date supports multiple roles for the TGF-β signaling pathway throughout schistosome development, in particular in the tegument which is at the interface with the host and between the male and female schistosome, development of vitelline cells in female worms whose genes and development are regulated by a stimulus from the male schistosome and embryogenesis of the egg. The human ligand TGF-β1 has been demonstrated to regulate the expression of a schistosome target gene that encodes a gynecophoric canal protein in the schistosome worm itself. Studies on signaling in schistosomes opens a new era for investigation of host-parasite and male-female interactions. PMID:17643432

  5. Interleukin 4 signals through two related pathways.

    PubMed

    Pernis, A; Witthuhn, B; Keegan, A D; Nelms, K; Garfein, E; Ihle, J N; Paul, W E; Pierce, J H; Rothman, P

    1995-08-15

    The interleukin 4 (IL-4) signaling pathway involves activation, by tyrosine phosphorylation, of two distinct substrates, a signal-transducing factor (STF-IL4) and the IL-4-induced phosphotyrosine substrate (4PS). It is not known whether the IL-4-mediated activation of these substrates occurs via related or distinct signaling pathways. We report that 32D cells, an IL-3-dependent myeloid progenitor cell line in which no phosphorylated 4PS is found, activate high levels of STF-IL4 in response to IL-4. Consistent with the known requirement for 4PS or insulin receptor substrate 1 (IRS-1) in IL-4-mediated mitogenesis, activation of STF-IL4 in 32D cells is not sufficient for IL-4-inducible c-myc expression. In addition, we have examined the ability of 32D cells transfected with different truncation mutants of the human IL-4 receptor to activate Jak-3 kinase and STF-IL4 in response to human IL-4. As in the case of 4PS/IRS-1, we have found that activation of both Jak-3 and STF-IL4 requires the presence of the IL-4 receptor region comprising aa 437-557. The finding that the same region of the IL-4 receptor is required for the induction of both 4PS/IRS-1 and STF-IL4 suggests that the IL-4-stimulated activation of these two substrates might involve common factors.

  6. Effect of triterpene acids of Eriobotrya japonica (Thunb.) Lindl. leaf and MAPK signal transduction pathway on inducible nitric oxide synthase expression in alveolar macrophage of chronic bronchitis rats.

    PubMed

    Huang, Y; Li, J; Meng, X M; Jiang, G L; Li, H; Cao, Q; Yu, S C; Lv, X W; Cheng, W M

    2009-01-01

    The goal of this study was to investigate the possible therapy mechanism of triterpene acids of Eriobotrya japonica (Thunb.) Lindl. Leaf (TAL) in alveolar macrophage (AM) of chronic bronchitis (CB) rats. CB model was established by injection of bacillus calmette guein (BCG) plus lipopolisacharide (LPS) in rats. TAL significantly inhibited the increased NO concentration, iNOS expression and phosphorylation of p38 MAPK in alveolar macrophages (AMs) of CB rats. Using in vivo test, we found that SB203580, a p38 MAPK inhibitor, (10 muM) significantly inhibited inducible nitric oxide synthase (iNOS) mRNA expression in AM. This data indicate that TAL highly decreases excessive iNOS expression and NO induction, and p38 MAPK signal transduction participates in iNOS expression and NO induction in AM of CB rats. The effect of TAL on iNOS expression in AM may be related to its inhibition of p38 MAPK signal transduction. PMID:19938219

  7. Mitochondrial Retrograde Signaling: Triggers, Pathways, and Outcomes

    PubMed Central

    da Cunha, Fernanda Marques; Torelli, Nicole Quesada; Kowaltowski, Alicia J.

    2015-01-01

    Mitochondria are essential organelles for eukaryotic homeostasis. Although these organelles possess their own DNA, the vast majority (>99%) of mitochondrial proteins are encoded in the nucleus. This situation makes systems that allow the communication between mitochondria and the nucleus a requirement not only to coordinate mitochondrial protein synthesis during biogenesis but also to communicate eventual mitochondrial malfunctions, triggering compensatory responses in the nucleus. Mitochondria-to-nucleus retrograde signaling has been described in various organisms, albeit with differences in effector pathways, molecules, and outcomes, as discussed in this review. PMID:26583058

  8. Building mammalian signalling pathways with RNAi screens.

    PubMed

    Moffat, Jason; Sabatini, David M

    2006-03-01

    Technological advances in mammalian systems are providing new tools to identify the molecular components of signalling pathways. Foremost among these tools is the ability to knock down gene function through the use of RNA interference (RNAi). The fact that RNAi can be scaled up for use in high-throughput techniques has motivated the creation of genome-wide RNAi reagents. We are now at the brink of being able to harness the power of RNAi for large-scale functional discovery in mammalian cells.

  9. The TAK1-TRAF6 signalling pathway.

    PubMed

    Landström, Marene

    2010-05-01

    Cellular responses to pathogens, growth factors, cytokines, extra- or intra-cellular stress, is a prerequisite for the cell to adapt to novel and potentially dangerous situations. If the changes in the extra- or intra-cellular milieu causes DNA-damage or revoke a signalling pathway utilized during morphogenesis, the epithelial cells might be forced to undergo programmed cell death (apoptosis) in the benefit for the whole organism or transform to a mesenchymal cell type (epithelial to mesenchymal transition; EMT), in respond to a specific stimuli. An overview is presented over the current knowledge for the key components in signal transduction in homeostasis, inflammation and cancer. A handful of transcription factors are crucial for the determination of the specific cellular responses, where the transforming growth factor-beta (TGF-beta) is an important factor as discussed in this review. PMID:20060931

  10. The retinoic acid signaling pathway regulates anterior/posterior patterning in the nerve cord and pharynx of amphioxus, a chordate lacking neural crest

    NASA Technical Reports Server (NTRS)

    Escriva, Hector; Holland, Nicholas D.; Gronemeyer, Hinrich; Laudet, Vincent; Holland, Linda Z.

    2002-01-01

    Amphioxus, the closest living invertebrate relative of the vertebrates, has a notochord, segmental axial musculature, pharyngeal gill slits and dorsal hollow nerve cord, but lacks neural crest. In amphioxus, as in vertebrates, exogenous retinoic acid (RA) posteriorizes the embryo. The mouth and gill slits never form, AmphiPax1, which is normally downregulated where gill slits form, remains upregulated and AmphiHox1 expression shifts anteriorly in the nerve cord. To dissect the role of RA signaling in patterning chordate embryos, we have cloned the single retinoic acid receptor (AmphiRAR), retinoid X receptor (AmphiRXR) and an orphan receptor (AmphiTR2/4) from amphioxus. AmphiTR2/4 inhibits AmphiRAR-AmphiRXR-mediated transactivation in the presence of RA by competing for DR5 or IR7 retinoic acid response elements (RAREs). The 5' untranslated region of AmphiTR2/4 contains an IR7 element, suggesting possible auto- and RA-regulation. The patterns of AmphiTR2/4 and AmphiRAR expression during embryogenesis are largely complementary: AmphiTR2/4 is strongly expressed in the cerebral vesicle (homologous to the diencephalon plus anterior midbrain), while AmphiRAR expression is high in the equivalent of the hindbrain and spinal cord. Similarly, while AmphiTR2/4 is expressed most strongly in the anterior and posterior thirds of the endoderm, the highest AmphiRAR expression is in the middle third. Expression of AmphiRAR is upregulated by exogenous RA and completely downregulated by the RA antagonist BMS009. Moreover, BMS009 expands the pharynx posteriorly; the first three gill slit primordia are elongated and shifted posteriorly, but do not penetrate, and additional, non-penetrating gill slit primordia are induced. Thus, in an organism without neural crest, initiation and penetration of gill slits appear to be separate events mediated by distinct levels of RA signaling in the pharyngeal endoderm. Although these compounds have little effect on levels of AmphiTR2/4 expression, RA

  11. MAPKs in development: insights from Dictyostelium signaling pathways

    PubMed Central

    Hadwiger, Jeffrey A.; Nguyen, Hoai-Nghia

    2011-01-01

    Mitogen activated protein kinases (MAPKs) play important roles in the development of eukaryotic organisms through the regulation of signal transduction pathways stimulated by external signals. MAPK signaling pathways have been associated with the regulation of cell growth, differentiation, and chemotaxis, indicating MAPKs contribute to a diverse set of developmental processes. In most eukaryotes, the diversity of external signals is likely to far exceed the diversity of MAPKs, suggesting that multiple signaling pathways might share MAPKs. Do different signaling pathways converge before MAPK function or can MAPKs maintain signaling specificity through interactions with specific proteins? The genetic and biochemical analysis of MAPK pathways in simple eukaryotes such as Dictyostelium offers opportunities to investigate functional specificity of MAPKs in G protein-mediated signal transduction pathways. This review considers the regulation and specificity of MAPK function in pathways that control Dictyostelium growth and development. PMID:21666837

  12. Triggering Apoptotic Death of Human Epidermal Keratinocytes by Malic Acid: Involvement of Endoplasmic Reticulum Stress- and Mitochondria-Dependent Signaling Pathways

    PubMed Central

    Hsiao, Yu-Ping; Lai, Wan-Wen; Wu, Shi-Bei; Tsai, Chung-Hung; Tang, Sheau-Chung; Chung, Jing-Gung; Yang, Jen-Hung

    2015-01-01

    Malic acid (MA) has been commonly used in cosmetic products, but the safety reports in skin are sparse. To investigate the biological effects of MA in human skin keratinocytes, we investigated the potential cytotoxicity and apoptotic effects of MA in human keratinocyte cell lines (HaCaT). The data showed that MA induced apoptosis based on the observations of DAPI staining, DNA fragmentation, and sub-G1 phase in HaCaT cells and normal human epidermal keratinocytes (NHEKs). Flow cytometric assays also showed that MA increased the production of mitochondrial superoxide (mito-SOX) but decreased the mitochondrial membrane potential. Analysis of bioenergetics function with the XF 24 analyzer Seahorse extracellular flux analyzer demonstrated that oxygen consumption rate (OCR) was significantly decreased whereas extracellular acidification rate (ECAR) was increased in MA-treated keratinocytes. The occurrence of apoptosis was proved by the increased expressions of FasL, Fas, Bax, Bid, caspases-3, -8, -9, cytochrome c, and the declined expressions of Bcl-2, PARP. MA also induced endoplasmic reticulum stress associated protein expression such as GRP78, GADD153, and ATF6α. We demonstrated that MA had anti-proliferative effect in HaCaT cell through the inhibition of cell cycle progression at G0/G1, and the induction of programmed cell death through endoplasmic reticulum stress- and mitochondria-dependent pathways. PMID:25584429

  13. Evaluation and Application of Dimethylated Amino Acids as Isobaric Tags for Quantitative Proteomics of the TGF-β/Smad3 Signaling Pathway.

    PubMed

    Yu, Qing; Shi, Xudong; Greer, Tyler; Lietz, Christopher B; Kent, K Craig; Li, Lingjun

    2016-09-01

    Isobaric labeling has become a widespread tool for quantitative proteomic studies. Here, we report the development and evaluation of several dimethylated amino acids as novel isobaric tags for quantitative proteomics. Four-plex dimethylated alanine (DiAla), valine (DiVal), and leucine (DiLeu) have been synthesized, sharing common features of peptide tagging and reporter ion production. DiAla and DiLeu are shown to achieve complete labeling. These two tags' impacts on peptide fragmentation and quantitation are further evaluated using HEK293 cell lysate. DiAla labeling generates more abundant backbone fragmentation whereas DiLeu labeling produces more intense reporter ions. Nonetheless, both tags enable accurate quantitative analysis of HEK293 cell proteomes. DiAla and DiLeu tags are then applied to study the TGF-β/Smad3 pathway with four differentially treated mouse vascular smooth muscle (MOVAS) cells. Our MS data reveal proteome-wide changes of AdSmad3 as compared to the GFP control, consistent with previous findings of causing smooth muscle cell (SMC) dedifferentiation.1 Additionally, the other two novel mutations on the hub protein Smad3, Y226A, and D408H, show compromised TGF-β/Smad3-dependent gene transcription and reversed phenotypic switch. These results are further corroborated with Western blotting and demonstrate that the novel DiAla and DiLeu isobaric tagging reagents provide useful tools for multiplex quantitative proteomics. PMID:27457343

  14. Exercise for the heart: signaling pathways

    PubMed Central

    Zhang, Haifeng; Xiao, Junjie; Li, Xinli

    2015-01-01

    Physical exercise, a potent functional intervention in protecting against cardiovascular diseases, is a hot topic in recent years. Exercise has been shown to reduce cardiac risk factors, protect against myocardial damage, and increase cardiac function. This improves quality of life and decreases mortality and morbidity in a variety of cardiovascular diseases, including myocardial infarction, cardiac ischemia/reperfusion injury, diabetic cardiomyopathy, cardiac aging, and pulmonary hypertension. The cellular adaptation to exercise can be associated with both endogenous and exogenous factors: 1) exercise induces cardiac growth via hypertrophy and renewal of cardiomyocytes, and 2) exercise induces endothelial progenitor cells to proliferate, migrate and differentiate into mature endothelial cells, giving rise to endothelial regeneration and angiogenesis. The cellular adaptations associated with exercise are due to the activation of several signaling pathways, in particular, the growth factor neuregulin1 (NRG1)-ErbB4-C/EBPβ and insulin-like growth factor (IGF)-1-PI3k-Akt signaling pathways. Of interest, microRNAs (miRNAs, miRs) such as miR-222 also play a major role in the beneficial effects of exercise. Thus, exploring the mechanisms mediating exercise-induced benefits will be instrumental for devising new effective therapies against cardiovascular diseases. PMID:26318584

  15. Lysophosphatidic Acid Signaling May Initiate Fetal Hydrocephalus

    PubMed Central

    Yung, Yun C.; Mutoh, Tetsuji; Lin, Mu-en; Noguchi, Kyoko; Rivera, Richard R.; Choi, Ji Woong; Kingsbury, Marcy A.; Chun, Jerold

    2013-01-01

    Fetal hydrocephalus (FH), characterized by the accumulation of cerebrospinal fluid (CSF), enlarged heads, histological defects, and neurological dysfunction, is the most common neurological disorder of newborns. Although the etiology of FH remains unclear, it is known to be associated with intracranial hemorrhage. Here, we report that lysophosphatidic acid (LPA), a blood-borne lipid that activates signaling through G protein-coupled receptors, provides a molecular explanation for FH associated with hemorrhage and other conditions that increase LPA levels. A mouse model of intracranial hemorrhage in which the brains of mouse embryos were exposed to blood or LPA resulted in characteristics of FH that were dependent on the presence of the LPA1 receptor expressed by neural progenitor cells (NPCs). Administration of an LPA1 receptor antagonist blocked development of FH. These findings identify the LPA signaling pathway in the etiology of FH and suggest potential targets toward developing new therapeutics to treat FH. PMID:21900594

  16. Altered retinoic acid signalling underpins dentition evolution.

    PubMed

    Gibert, Yann; Samarut, Eric; Pasco-Viel, Emmanuel; Bernard, Laure; Borday-Birraux, Véronique; Sadier, Alexa; Labbé, Catherine; Viriot, Laurent; Laudet, Vincent

    2015-03-01

    Small variations in signalling pathways have been linked to phenotypic diversity and speciation. In vertebrates, teeth represent a reservoir of adaptive morphological structures that are prone to evolutionary change. Cyprinid fish display an impressive diversity in tooth number, but the signals that generate such diversity are unknown. Here, we show that retinoic acid (RA) availability influences tooth number size in Cyprinids. Heterozygous adult zebrafish heterozygous for the cyp26b1 mutant that encodes an enzyme able to degrade RA possess an extra tooth in the ventral row. Expression analysis of pharyngeal mesenchyme markers such as dlx2a and lhx6 shows lateral, anterior and dorsal expansion of these markers in RA-treated embryos, whereas the expression of the dental epithelium markers dlx2b and dlx3b is unchanged. Our analysis suggests that changes in RA signalling play an important role in the diversification of teeth in Cyprinids. Our work illustrates that through subtle changes in the expression of rate-limiting enzymes, the RA pathway is an active player of tooth evolution in fish.

  17. Signaling pathways take aim at neurotransmitter transporters.

    PubMed

    Robinson, Michael B

    2003-11-01

    Neurotransmitter transporters are the target of various pharmacological agents used to treat psychological or cognitive conditions, such as depression and attention-deficit disorder. In addition, some of the effects of stimulant-type drugs of abuse result from inhibition of neurotransmitter transporters. Robinson describes the intersection between neurotransmitter transporters and signaling pathways. Neurotransmitter transporters can be regulated by altering the rate of internalization and insertion into the plasma membrane to control cell surface expression or by altering the activity of the transporters within the membrane. As the mechanisms governing regulation of these transporters become elucidated, new potential therapeutic targets may be revealed, given the many processes affected by the activity of neurotransmitter transporters.

  18. Signaling pathways in melanosome biogenesis and pathology.

    PubMed

    Schiaffino, Maria Vittoria

    2010-07-01

    Melanosomes are the specialized intracellular organelles of pigment cells devoted to the synthesis, storage and transport of melanin pigments, which are responsible for most visible pigmentation in mammals and other vertebrates. As a direct consequence, any genetic mutation resulting in alteration of melanosomal function, either because affecting pigment cell survival, migration and differentiation, or because interfering with melanosome biogenesis, transport and transfer to keratinocytes, is immediately translated into color variations of skin, fur, hair or eyes. Thus, over 100 genes and proteins have been identified as pigmentary determinants in mammals, providing us with a deep understanding of this biological system, which functions by using mechanisms and processes that have parallels in other tissues and organs. In particular, many genes implicated in melanosome biogenesis have been characterized, so that melanosomes represent an incredible source of information and a model for organelles belonging to the secretory pathway. Furthermore, the function of melanosomes can be associated with common physiological phenotypes, such as variation of pigmentation among individuals, and with rare pathological conditions, such as albinism, characterized by severe visual defects. Among the most relevant mechanisms operating in melanosome biogenesis are the signal transduction pathways mediated by two peculiar G protein-coupled receptors: the melanocortin-1 receptor (MC1R), involved in the fair skin/red hair phenotype and skin cancer; and OA1 (GPR143), whose loss-of-function results in X-linked ocular albinism. This review will focus on the most recent novelties regarding the functioning of these two receptors, by highlighting emerging signaling mechanisms and general implications for cell biology and pathology. PMID:20381640

  19. GmCYP82A3, a Soybean Cytochrome P450 Family Gene Involved in the Jasmonic Acid and Ethylene Signaling Pathway, Enhances Plant Resistance to Biotic and Abiotic Stresses.

    PubMed

    Yan, Qiang; Cui, Xiaoxia; Lin, Shuai; Gan, Shuping; Xing, Han; Dou, Daolong

    2016-01-01

    The cytochrome P450 monooxygenases (P450s) represent a large and important enzyme superfamily in plants. They catalyze numerous monooxygenation/hydroxylation reactions in biochemical pathways, P450s are involved in a variety of metabolic pathways and participate in the homeostasis of phytohormones. The CYP82 family genes specifically reside in dicots and are usually induced by distinct environmental stresses. However, their functions are largely unknown, especially in soybean (Glycine max L.). Here, we report the function of GmCYP82A3, a gene from soybean CYP82 family. Its expression was induced by Phytophthora sojae infection, salinity and drought stresses, and treatment with methyl jasmonate (MeJA) or ethephon (ETH). Its expression levels were consistently high in resistant cultivars. Transgenic Nicotiana benthamiana plants overexpressing GmCYP82A3 exhibited strong resistance to Botrytis cinerea and Phytophthora parasitica, and enhanced tolerance to salinity and drought stresses. Furthermore, transgenic plants were less sensitive to jasmonic acid (JA), and the enhanced resistance was accompanied with increased expression of the JA/ET signaling pathway-related genes. PMID:27588421

  20. GmCYP82A3, a Soybean Cytochrome P450 Family Gene Involved in the Jasmonic Acid and Ethylene Signaling Pathway, Enhances Plant Resistance to Biotic and Abiotic Stresses

    PubMed Central

    Yan, Qiang; Cui, Xiaoxia; Lin, Shuai; Gan, Shuping; Xing, Han; Dou, Daolong

    2016-01-01

    The cytochrome P450 monooxygenases (P450s) represent a large and important enzyme superfamily in plants. They catalyze numerous monooxygenation/hydroxylation reactions in biochemical pathways, P450s are involved in a variety of metabolic pathways and participate in the homeostasis of phytohormones. The CYP82 family genes specifically reside in dicots and are usually induced by distinct environmental stresses. However, their functions are largely unknown, especially in soybean (Glycine max L.). Here, we report the function of GmCYP82A3, a gene from soybean CYP82 family. Its expression was induced by Phytophthora sojae infection, salinity and drought stresses, and treatment with methyl jasmonate (MeJA) or ethephon (ETH). Its expression levels were consistently high in resistant cultivars. Transgenic Nicotiana benthamiana plants overexpressing GmCYP82A3 exhibited strong resistance to Botrytis cinerea and Phytophthora parasitica, and enhanced tolerance to salinity and drought stresses. Furthermore, transgenic plants were less sensitive to jasmonic acid (JA), and the enhanced resistance was accompanied with increased expression of the JA/ET signaling pathway-related genes. PMID:27588421

  1. Rhamnolipids elicit defense responses and induce disease resistance against biotrophic, hemibiotrophic, and necrotrophic pathogens that require different signaling pathways in Arabidopsis and highlight a central role for salicylic acid.

    PubMed

    Sanchez, Lisa; Courteaux, Barbara; Hubert, Jane; Kauffmann, Serge; Renault, Jean-Hugues; Clément, Christophe; Baillieul, Fabienne; Dorey, Stéphan

    2012-11-01

    Plant resistance to phytopathogenic microorganisms mainly relies on the activation of an innate immune response usually launched after recognition by the plant cells of microbe-associated molecular patterns. The plant hormones, salicylic acid (SA), jasmonic acid, and ethylene have emerged as key players in the signaling networks involved in plant immunity. Rhamnolipids (RLs) are glycolipids produced by bacteria and are involved in surface motility and biofilm development. Here we report that RLs trigger an immune response in Arabidopsis (Arabidopsis thaliana) characterized by signaling molecules accumulation and defense gene activation. This immune response participates to resistance against the hemibiotrophic bacterium Pseudomonas syringae pv tomato, the biotrophic oomycete Hyaloperonospora arabidopsidis, and the necrotrophic fungus Botrytis cinerea. We show that RL-mediated resistance involves different signaling pathways that depend on the type of pathogen. Ethylene is involved in RL-induced resistance to H. arabidopsidis and to P. syringae pv tomato whereas jasmonic acid is essential for the resistance to B. cinerea. SA participates to the restriction of all pathogens. We also show evidence that SA-dependent plant defenses are potentiated by RLs following challenge by B. cinerea or P. syringae pv tomato. These results highlight a central role for SA in RL-mediated resistance. In addition to the activation of plant defense responses, antimicrobial properties of RLs are thought to participate in the protection against the fungus and the oomycete. Our data highlight the intricate mechanisms involved in plant protection triggered by a new type of molecule that can be perceived by plant cells and that can also act directly onto pathogens. PMID:22968829

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

    PubMed

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

    2016-01-01

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

  3. Mechanisms of disease: signaling pathways and immunobiology of inflammatory myopathies.

    PubMed

    Dalakas, Marinos C

    2006-04-01

    The signaling pathways involved in the immunobiology of polymyositis, dermatomyositis, and inclusion-body myositis are outlined in this Review, which is based on research performed during the past 10 years. In dermatomyositis, the complement cascade is activated and the expression of cytokines and chemokines is upregulated. In polymyositis and inclusion-body myositis, autoinvasive CD8+ T cells are clonally expanded. This T-cell subset possesses conserved amino-acid sequences in complementarity-determining region 3 of the T-cell receptor and, via the perforin pathway, exerts a myotoxic effect on muscle fibers that express major histocompatibility complex (MHC) class I molecules. In all inflammatory myopathies, molecules associated with T-cell transmigration and cytokine signaling, as well as chemokines and their receptors, are strongly expressed by endothelial and inflammatory cells. Early in the pathogenesis of polymyositis and inclusion-body myositis, expression of MHC class I molecules on muscle fibers is upregulated, even in the absence of autoinvasive CD8+ T cells. Emerging data indicate that such continuous upregulation of the expression of MHC class I molecules on muscle fibers leads to an endoplasmic reticulum stress response, intracellular accumulation of misfolded glycoproteins, and activation of nuclear factor kappaB pathways, which can further stimulate formation of MHC class I-CD8 complexes, resulting in a self-sustaining inflammatory response. Advances in our understanding of the signaling pathways involved in the pathogenesis of these inflammatory myopathies are expected to result in the identification of novel therapeutic targets for these diseases.

  4. Canonical RTK-Ras-ERK signaling and related alternative pathways

    PubMed Central

    Sundaram, Meera V.

    2013-01-01

    Receptor Tyrosine Kinase (RTK)-Ras-Extracellular signal-regulated kinase (ERK) signaling pathways control many aspects of C. elegans development and behavior. Studies in C. elegans helped elucidate the basic framework of the RTK-Ras-ERK pathway and continue to provide insights into its complex regulation, its biological roles, how it elicits cell-type appropriate responses, and how it interacts with other signaling pathways to do so. C. elegans studies have also revealed biological contexts in which alternative RTK- or Ras-dependent pathways are used instead of the canonical pathway. PMID:23908058

  5. Connecting proline metabolism and signaling pathways in plant senescence

    PubMed Central

    Zhang, Lu; Becker, Donald F.

    2015-01-01

    The amino acid proline has a unique biological role in stress adaptation. Proline metabolism is manipulated under stress by multiple and complex regulatory pathways and can profoundly influence cell death and survival in microorganisms, plants, and animals. Though the effects of proline are mediated by diverse signaling pathways, a common theme appears to be the generation of reactive oxygen species (ROS) due to proline oxidation being coupled to the respiratory electron transport chain. Considerable research has been devoted to understand how plants exploit proline metabolism in response to abiotic and biotic stress. Here, we review potential mechanisms by which proline metabolism influences plant senescence, namely in the petal and leaf. Recent studies of petal senescence suggest proline content is manipulated to meet energy demands of senescing cells. In the flower and leaf, proline metabolism may influence ROS signaling pathways that delay senescence progression. Future studies focusing on the mechanisms by which proline metabolic shifts occur during senescence may lead to novel methods to rescue crops under stress and to preserve post-harvest agricultural products. PMID:26347750

  6. Transcriptional regulation of human mucin MUC4 by bile acids in oesophageal cancer cells is promoter-dependent and involves activation of the phosphatidylinositol 3-kinase signalling pathway.

    PubMed Central

    Mariette, Christophe; Perrais, Michaël; Leteurtre, Emmanuelle; Jonckheere, Nicolas; Hémon, Brigitte; Pigny, Pascal; Batra, Surinder; Aubert, Jean-Pierre; Triboulet, Jean-Pierre; Van Seuningen, Isabelle

    2004-01-01

    Abnormal gastro-oesophageal reflux and bile acids have been linked to the presence of Barrett's oesophageal premalignant lesion associated with an increase in mucin-producing goblet cells and MUC4 mucin gene overexpression. However, the molecular mechanisms underlying the regulation of MUC4 by bile acids are unknown. Since total bile is a complex mixture, we undertook to identify which bile acids are responsible for MUC4 up-regulation by using a wide panel of bile acids and their conjugates. MUC4 apomucin expression was studied by immunohistochemistry both in patient biopsies and OE33 oesophageal cancer cell line. MUC4 mRNA levels and promoter regulation were studied by reverse transcriptase-PCR and transient transfection assays respectively. We show that among the bile acids tested, taurocholic, taurodeoxycholic, taurochenodeoxycholic and glycocholic acids and sodium glycocholate are strong activators of MUC4 expression and that this regulation occurs at the transcriptional level. By using specific pharmacological inhibitors of mitogen-activated protein kinase, phosphatidylinositol 3-kinase, protein kinase A and protein kinase C, we demonstrate that bile acid-mediated up-regulation of MUC4 is promoter-specific and mainly involves activation of phosphatidylinositol 3-kinase. This new mechanism of regulation of MUC4 mucin gene points out an important role for bile acids as key molecules in targeting MUC4 overexpression in early stages of oesophageal carcinogenesis. PMID:14583090

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

    PubMed

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

    2015-01-01

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

  8. Dietary influence on MAPK-signaling pathways and risk of colon and rectal cancer

    PubMed Central

    Slattery, Martha L.; Lundgreen, Abbie; Wolff, Roger K.

    2014-01-01

    Mitogen-activated protein kinase (MAPK) pathways regulate cellular functions including cell proliferation, differentiation, migration, and apoptosis. Associations between genes in the DUSP, ERK1/2, JNK, and p38 MAPK-signaling pathways and dietary factors associated with growth factors, inflammation, and oxidative stress and risk of colon and rectal cancer were evaluated. Data include colon cases (n=1555) and controls (n=1956) and rectal cases (n=754) and controls (n=959). Statistically significant interactions were observed for the MAPK-signaling pathways after adjustment for multiple comparisons. DUSP genes interacted with carbohydrates, mutagen index, calories, calcium, vitamin D, lycopene, dietary fats, folic acid, and selenium. MAPK1, MAPK3, MAPK1 and RAF1 within the ERK1/2 MAPK-signaling pathway interacted with dietary fats and cruciferous vegetables. Within the JNK MAPK-signaling pathway, interactions between MAP3K7 and protein, vitamin C, iron, folic acid, carbohydrates, and cruciferous vegetables; MAP3K10 and folic acid; MAP3K9 and lutein/zeaxanthin; MAPK8 and calcium; MAP3K3 and calcium and lutein; MAP3K1 and cruciferous vegetables. Interaction within the p38-signaling pathway included: MAPK14 with calories, carbohydrates saturated fat, selenium, vitamin C; MAP3K2 and carbohydrates, and folic acid. These data suggest that dietary factors involved in inflammation and oxidative stress interact with MAPK-signaling genes to alter risk of colorectal cancer. PMID:23859041

  9. Cerebral insulin, insulin signaling pathway, and brain angiogenesis.

    PubMed

    Zeng, Yi; Zhang, Le; Hu, Zhiping

    2016-01-01

    Insulin performs unique non-metabolic functions within the brain. Broadly speaking, two major areas of these functions are those related to brain endothelial cells and the blood-brain barrier (BBB) function, and those related to behavioral effects, like cognition in disease states (Alzheimer's disease, AD) and in health. Recent studies showed that both these functions are associated with brain angiogenesis. These findings raise interesting questions such as how they are linked to each other and whether modifying brain angiogenesis by targeting certain insulin signaling pathways could be an effective strategy to treat dementia as in AD, or even to help secure healthy longevity. The two canonical downstream pathways involved in mediating the insulin signaling pathway, the phosphoinositide-3 kinase (PI3K), and mitogen-activated protein kinase (MAPK) cascades, in the brain are supposed to be similar to those in the periphery. PI3K and MAPK pathways play important roles in angiogenesis. Both are involved in stimulating hypoxia inducible factor (HIF) in angiogenesis and could be activated by the insulin signaling pathway. This suggests that PI3K and MAPK pathways might act as cross-talk between the insulin signaling pathway and the angiogenesis pathway in brain. But the cerebral insulin, insulin signaling pathway, and the detailed mechanism in the connection of insulin signaling pathway, brain angiogenesis pathway, and healthy aging or dementias are still mostly not clear and need further studies.

  10. Bile acid signaling and liver regeneration.

    PubMed

    Fan, Mingjie; Wang, Xichun; Xu, Ganyu; Yan, Qingfeng; Huang, Wendong

    2015-02-01

    The liver is able to regenerate itself in response to partial hepatectomy or liver injury. This is accomplished by a complex network of different cell types and signals both inside and outside the liver. Bile acids (BAs) are recently identified as liver-specific metabolic signals and promote liver regeneration by activating their receptors: Farnesoid X Receptor (FXR) and G-protein-coupled BA receptor 1 (GPBAR1, or TGR5). FXR is a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors. FXR promotes liver regeneration after 70% partial hepatectomy (PHx) or liver injury. Moreover, activation of FXR is able to alleviate age-related liver regeneration defects. Both liver- and intestine-FXR are activated by BAs after liver resection or injury and promote liver regeneration through distinct mechanism. TGR5 is a membrane-bound BA receptor and it is also activated during liver regeneration. TGR5 regulates BA hydrophobicity and stimulates BA excretion in urine during liver regeneration. BA signaling thus represents a novel metabolic pathway during liver regeneration. This article is part of a Special Issue entitled: Nuclear receptors in animal development.

  11. Long-chain omega-3 fatty acids regulate bovine whole-body protein metabolism by promoting muscle insulin signalling to the Akt–mTOR–S6K1 pathway and insulin sensitivity

    PubMed Central

    Gingras, Andrée-Anne; White, Phillip James; Chouinard, P Yvan; Julien, Pierre; Davis, Teresa A; Dombrowski, Luce; Couture, Yvon; Dubreuil, Pascal; Myre, Alexandre; Bergeron, Karen; Marette, André; Thivierge, M Carole

    2007-01-01

    The ability of the skeletal musculature to use amino acids to build or renew constitutive proteins is gradually lost with age and this is partly due to a decline in skeletal muscle insulin sensitivity. Since long-chain omega-3 polyunsaturated fatty acids (LCn–3PUFA) from fish oil are known to improve insulin-mediated glucose metabolism in insulin-resistant states, their potential role in regulating insulin-mediated protein metabolism was investigated in this study. Experimental data are based on a switchback design composed of three 5 week experimental periods using six growing steers to compare the effect of a continuous abomasal infusion of LCn–3PUFA-rich menhaden oil with an iso-energetic control oil mixture. Clamp and insulin signalling observations were combined with additional data from a second cohort of six steers. We found that enteral LCn–3PUFA potentiate insulin action by increasing the insulin-stimulated whole-body disposal of amino acids from 152 to 308 μmol kg−1 h−1 (P = 0.006). The study further showed that in the fed steady-state, chronic adaptation to LCn–3PUFA induces greater activation (P < 0.05) of the Akt–mTOR–S6K1 signalling pathway. Simultaneously, whole-body total flux of phenylalanine was reduced from 87 to 67 μmol kg−1 h−1 (P = 0.04) and oxidative metabolism was decreased (P = 0.05). We conclude that chronic feeding of menhaden oil provides a novel nutritional mean to enhance insulin-sensitive aspects of protein metabolism. PMID:17158167

  12. Long-chain omega-3 fatty acids regulate bovine whole-body protein metabolism by promoting muscle insulin signalling to the Akt-mTOR-S6K1 pathway and insulin sensitivity.

    PubMed

    Gingras, Andrée-Anne; White, Phillip James; Chouinard, P Yvan; Julien, Pierre; Davis, Teresa A; Dombrowski, Luce; Couture, Yvon; Dubreuil, Pascal; Myre, Alexandre; Bergeron, Karen; Marette, André; Thivierge, M Carole

    2007-02-15

    The ability of the skeletal musculature to use amino acids to build or renew constitutive proteins is gradually lost with age and this is partly due to a decline in skeletal muscle insulin sensitivity. Since long-chain omega-3 polyunsaturated fatty acids (LCn-3PUFA) from fish oil are known to improve insulin-mediated glucose metabolism in insulin-resistant states, their potential role in regulating insulin-mediated protein metabolism was investigated in this study. Experimental data are based on a switchback design composed of three 5 week experimental periods using six growing steers to compare the effect of a continuous abomasal infusion of LCn-3PUFA-rich menhaden oil with an iso-energetic control oil mixture. Clamp and insulin signalling observations were combined with additional data from a second cohort of six steers. We found that enteral LCn-3PUFA potentiate insulin action by increasing the insulin-stimulated whole-body disposal of amino acids from 152 to 308 micromol kg(-1) h(-1) (P=0.006). The study further showed that in the fed steady-state, chronic adaptation to LCn-3PUFA induces greater activation (P<0.05) of the Akt-mTOR-S6K1 signalling pathway. Simultaneously, whole-body total flux of phenylalanine was reduced from 87 to 67 micromol kg(-1) h(-1) (P=0.04) and oxidative metabolism was decreased (P=0.05). We conclude that chronic feeding of menhaden oil provides a novel nutritional mean to enhance insulin-sensitive aspects of protein metabolism. PMID:17158167

  13. Amino acid transporters: roles in amino acid sensing and signalling in animal cells.

    PubMed Central

    Hyde, Russell; Taylor, Peter M; Hundal, Harinder S

    2003-01-01

    Amino acid availability regulates cellular physiology by modulating gene expression and signal transduction pathways. However, although the signalling intermediates between nutrient availability and altered gene expression have become increasingly well documented, how eukaryotic cells sense the presence of either a nutritionally rich or deprived medium is still uncertain. From recent studies it appears that the intracellular amino acid pool size is particularly important in regulating translational effectors, thus, regulated transport of amino acids across the plasma membrane represents a means by which the cellular response to amino acids could be controlled. Furthermore, evidence from studies with transportable amino acid analogues has demonstrated that flux through amino acid transporters may act as an initiator of nutritional signalling. This evidence, coupled with the substrate selectivity and sensitivity to nutrient availability classically associated with amino acid transporters, plus the recent discovery of transporter-associated signalling proteins, demonstrates a potential role for nutrient transporters as initiators of cellular nutrient signalling. Here, we review the evidence supporting the idea that distinct amino acid "receptors" function to detect and transmit certain nutrient stimuli in higher eukaryotes. In particular, we focus on the role that amino acid transporters may play in the sensing of amino acid levels, both directly as initiators of nutrient signalling and indirectly as regulators of external amino acid access to intracellular receptor/signalling mechanisms. PMID:12879880

  14. Berberine attenuates high glucose-induced fibrosis by activating the G protein-coupled bile acid receptor TGR5 and repressing the S1P2/MAPK signaling pathway in glomerular mesangial cells.

    PubMed

    Yang, Zhiying; Li, Jie; Xiong, Fengxiao; Huang, Junying; Chen, Cheng; Liu, Peiqing; Huang, Heqing

    2016-08-15

    Berberine (BBR) exerts powerful renoprotective effects on diabetic nephropathy (DN), but the underlying mechanisms remain unclear. We previously demonstrated that activation of the G protein-coupled bile acid receptor TGR5 ameliorates diabetic nephropathy by inhibiting the activation of the sphingosine 1-phosphate (S1P)/sphingosine 1-phosphate receptor 2 (S1P2) signaling pathway. In this study, we explored the role of TGR5 in the BBR-induced downregulation of sphingosine 1-phosphate receptor 2 (S1P2)/mitogen-activated protein kinase (MAPK)-mediated fibrosis in glomerular mesangial cells (GMCs). Results showed that, BBR suppressed the expression of FN, ICAM-1, and TGF-β1 in high-glucose cultures of GMCs, and the phosphorylation level of c-Jun/c-Fos was downregulated. The high glucose lowered TGR5 expression in a time-dependent manner; this effect was reversed by BBR in a dose-dependent manner. The TGR5 agonist INT-777 decreased the high glucose-induced FN, ICAM-1, and TGF-β1 protein contents. In addition, TGR5 siRNA blocked S1P2 degradation by BBR. And MAPK signaling, which plays important regulatory roles in the pathological progression of DN, was activated by TGR5 siRNA. Apart from this, MAPK signaling as well as FN, ICAM-1, and TGF-β1 suppressed by BBR under high glucose conditions were limited by TGR5 depletion. Thus, BBR decreases FN, ICAM-1, and TGF-β1 levels under high glucose conditions in GMCs possibly by activating TGR5 and inhibiting S1P2/MAPK signaling. PMID:27292312

  15. The Hippo signaling pathway in stem cell biology and cancer.

    PubMed

    Mo, Jung-Soon; Park, Hyun Woo; Guan, Kun-Liang

    2014-06-01

    The Hippo signaling pathway, consisting of a highly conserved kinase cascade (MST and Lats) and downstream transcription coactivators (YAP and TAZ), plays a key role in tissue homeostasis and organ size control by regulating tissue-specific stem cells. Moreover, this pathway plays a prominent role in tissue repair and regeneration. Dysregulation of the Hippo pathway is associated with cancer development. Recent studies have revealed a complex network of upstream inputs, including cell density, mechanical sensation, and G-protein-coupled receptor (GPCR) signaling, that modulate Hippo pathway activity. This review focuses on the role of the Hippo pathway in stem cell biology and its potential implications in tissue homeostasis and cancer.

  16. Charged Amino Acid-rich Leucine Zipper-1 (Crlz-1) as a Target of Wnt Signaling Pathway Controls Pre-B Cell Proliferation by Affecting Runx/CBFβ-targeted VpreB and λ5 Genes.

    PubMed

    Choi, Seung-Young; Park, Sung-Kyun; Yoo, Han-Woong; Pi, Joo-Hyun; Kang, Chang-Joong

    2016-07-15

    The proliferation of pre-B cells is known to further increase the clonal diversity of B cells at the stage of pre-B cells by allowing the same rearranged heavy chains to combine with differently rearranged light chains in a subsequent developmental stage. Crlz-1 (charged amino acid-rich leucine zipper-1) was found to control this proliferation of pre-B cells by working as a Wnt (wingless-related mouse mammary tumor virus integration site) target gene in these cells. Mechanistically, Crlz-1 protein functioned by mobilizing cytoplasmic CBFβ (core binding factor β) into the nucleus to allow Runx (runt-related transcription factor)/CBFβ heterodimerization. Runx/CBFβ then turned on its target genes such as EBF (early B cell factor), VpreB, and λ5 and thereby pre-B cell receptor signaling, leading to the expression of cyclins D2 and D3 Actually, the proliferative function of Crlz-1 was demonstrated by not only Crlz-1 or β-catenin knockdown but also Crlz-1 overexpression. Furthermore, the mechanistic view that the proliferative function of Crlz-1 is caused by relaying Wnt/β-catenin to pre-B cell receptor signaling pathways through the regulation of Runx/CBFβ heterodimerization was also verified by employing niclosamide, XAV939, and LiCl as Wnt inhibitors and activator, respectively. PMID:27226553

  17. Suppression of MMP-9 and FAK expression by pomolic acid via blocking of NF-κB/ERK/mTOR signaling pathways in growth factor-stimulated human breast cancer cells.

    PubMed

    Park, Ji-Hyun; Cho, Yoon Young; Yoon, Seong Woo; Park, Byoungduck

    2016-09-01

    The expression of matrix metalloproteinase-9 (MMP-9) and the phosphorylation of focal adhesion kinase (FAK) have been implicated in the invasion, metastasis and cell motility of cancer cells. It is considered that epidermal growth factor (EGF) may increase cell motility, an event involved in cancer cell invasion and metastasis. Pomolic acid (PA), an active triterpenoid from Euscaphis japonica, is known to inhibit the proliferation of a variety of cancer cells, but the effect of PA on the invasiveness of cancer cells is largely unknown. In this study, we first determined the molecular mechanism by which PA inhibits the migratory and invasive abilities of highly metastatic MDA-MB‑231 cells. Transwell invasion, wound-healing assay and F-actin reorganization showed that PA significantly inhibits the EGF-induced invasion, migration and cell motility by reducing expression of MMP-9 and FAK phosphorylation. In particular, PA potently suppressed the phosphorylation of nuclear factor (NF)-κB, extraceullar signal-regulated kinase (ERK), phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway. Furthermore, PA treatment inhibited the DNA binding activity of NF-κB and activator protein (AP)-1, which is known to mediate the expression of EGFR and MMP-9. These results suggest that PA may be a potential therapeutic candidate for treatment of breast cancer metastasis. PMID:27573547

  18. Targeting the WNT Signaling Pathway in Cancer Therapeutics.

    PubMed

    Tai, David; Wells, Keith; Arcaroli, John; Vanderbilt, Chad; Aisner, Dara L; Messersmith, Wells A; Lieu, Christopher H

    2015-10-01

    The WNT signaling cascade is integral in numerous biological processes including embryonic development, cell cycle regulation, inflammation, and cancer. Hyperactivation of WNT signaling secondary to alterations to varying nodes of the pathway have been identified in multiple tumor types. These alterations converge into increased tumorigenicity, sustained proliferation, and enhanced metastatic potential. This review seeks to evaluate the evidence supporting the WNT pathway in cancer, the therapeutic strategies in modulating this pathway, and potential challenges in drug development.

  19. Effect of 5-caffeoylquinic acid on the NF-κB signaling pathway, peroxisome proliferator-activated receptor gamma 2, and macrophage infiltration in high-fat diet-fed Sprague-Dawley rat adipose tissue.

    PubMed

    Liu, Si-Le; Peng, Bing-Jie; Zhong, Ying-Li; Liu, Yun-Long; Song, Zhuo; Wang, Zheng

    2015-08-01

    Obesity, considered as a consequence of overnutrition, sustains a low-degree inflammatory state and results in insulin-resistance and type 2 diabetes. Here, we investigated the anti-inflammatory effects of 5-caffeoylquinic acid (5-CQA) in high-fat diet-induced obese rats. Serum interleukin (IL)-6, monocyte chemotactic protein 1 (MCP-1), tumor necrosis factor-alpha (TNF-α), total cholesterol (TC), triglyceride (TG), and free fatty acid (FFA) levels were determined. Expression of genes related to TG metabolism, macrophage biomarkers, and inflammation was assessed by real-time PCR. Protein expression of NF-κB, PPARγ2, and phosphorylated IκBα was evaluated by western blotting, and the histology of adipose tissue was examined. Supplementation of the rat diet with 5-CQA reduced obesity development, macrophage infiltration, and steatosis. Additionally, 5-CQA decreased the expression of NF-κB and downstream inflammatory cytokines, but increased the expression of PPARγ2, in a dose-dependent manner. Thus, 5-CQA improved obesity and obesity-related metabolic disturbances via PPARγ2 and the NF-κB signaling pathway.

  20. Signaling Pathways in Thyroid Cancer and Their Therapeutic Implications

    PubMed Central

    Jin, Shan; Borkhuu, Oyungerel; Bao, Wuyuntu; Yang, Yun-Tian

    2016-01-01

    Thyroid cancer is a common malignancy of endocrine system, and has now become the fastest increasing cancer among all the malignancies. The development, progression, invasion, and metastasis are closely associated with multiple signaling pathways and the functions of related molecules, such as Src, Janus kinase (JAK)-signal transducers and activators of transcription (STAT), mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)/Akt, NF-κB, thyroid stimulating hormone receptor (TSHR), Wnt-β-catenin and Notch signaling pathways. Each of the signaling pathways could exert its function singly or through network with other pathways. These pathways could cooperate, promote, antagonize, or interact with each other to form a complex network for the regulation. Dysfunction of this network could increase the development, progression, invasion, and metastasis of thyroid cancer. Inoperable thyroid cancer still has a poor prognosis. However, signaling pathway-related targeted therapies offer the hope of longer quality of meaningful life for this small group of patients. Signaling pathway-related targets provide unprecedented opportunities for further research and clinical development of novel treatment strategies for this cancer. In the present work, the advances in these signaling pathways and targeted treatments of thyroid cancer were reviewed. PMID:26985248

  1. Role of bile acids in the regulation of the metabolic pathways

    PubMed Central

    Taoka, Hiroki; Yokoyama, Yoko; Morimoto, Kohkichi; Kitamura, Naho; Tanigaki, Tatsuya; Takashina, Yoko; Tsubota, Kazuo; Watanabe, Mitsuhiro

    2016-01-01

    Recent studies have revealed that bile acids (BAs) are not only facilitators of dietary lipid absorption but also important signaling molecules exerting multiple physiological functions. Some major signaling pathways involving the nuclear BAs receptor farnesoid X receptor and the G protein-coupled BAs receptor TGR5/M-BAR have been identified to be the targets of BAs. BAs regulate their own homeostasis via signaling pathways. BAs also affect diverse metabolic pathways including glucose metabolism, lipid metabolism and energy expenditure. This paper suggests the mechanism of controlling metabolism via BA signaling and demonstrates that BA signaling is an attractive therapeutic target of the metabolic syndrome. PMID:27433295

  2. Information processing in multi-step signaling pathways

    NASA Astrophysics Data System (ADS)

    Ganesan, Ambhi; Hamidzadeh, Archer; Zhang, Jin; Levchenko, Andre

    Information processing in complex signaling networks is limited by a high degree of variability in the abundance and activity of biochemical reactions (biological noise) operating in living cells. In this context, it is particularly surprising that many signaling pathways found in eukaryotic cells are composed of long chains of biochemical reactions, which are expected to be subject to accumulating noise and delayed signal processing. Here, we challenge the notion that signaling pathways are insulated chains, and rather view them as parts of extensively branched networks, which can benefit from a low degree of interference between signaling components. We further establish conditions under which this pathway organization would limit noise accumulation, and provide evidence for this type of signal processing in an experimental model of a calcium-activated MAPK cascade. These results address the long-standing problem of diverse organization and structure of signaling networks in live cells.

  3. The hypoxia signaling pathway and hypoxic adaptation in fishes.

    PubMed

    Xiao, Wuhan

    2015-02-01

    The hypoxia signaling pathway is an evolutionarily conserved cellular signaling pathway present in animals ranging from Caenorhabditis elegans to mammals. The pathway is crucial for oxygen homeostasis maintenance. Hypoxia-inducible factors (HIF-1α and HIF-2α) are master regulators in the hypoxia signaling pathway. Oxygen concentrations vary a lot in the aquatic environment. To deal with this, fishes have adapted and developed varying strategies for living in hypoxic conditions. Investigations into the strategies and mechanisms of hypoxia adaptation in fishes will allow us to understand fish speciation and breed hypoxia-tolerant fish species/strains. This review summarizes the process of the hypoxia signaling pathway and its regulation, as well as the mechanism of hypoxia adaptation in fishes.

  4. Quercetin Protects against Okadaic Acid-Induced Injury via MAPK and PI3K/Akt/GSK3β Signaling Pathways in HT22 Hippocampal Neurons.

    PubMed

    Jiang, Wei; Luo, Tao; Li, Sheng; Zhou, Yue; Shen, Xiu-Yin; He, Feng; Xu, Jie; Wang, Hua-Qiao

    2016-01-01

    Increasing evidence shows that oxidative stress and the hyperphosphorylation of tau protein play essential roles in the progression of Alzheimer's disease (AD). Quercetin is a major flavonoid that has anti-oxidant, anti-cancer and anti-inflammatory properties. We investigated the neuroprotective effects of quercetin to HT22 cells (a cell line from mouse hippocampal neurons). We found that Okadaic acid (OA) induced the hyperphosphorylation of tau protein at Ser199, Ser396, Thr205, and Thr231 and produced oxidative stress to the HT22 cells. The oxidative stress suppressed the cell viability and decreased the levels of lactate dehydrogenase (LDH), superoxide dismutase (SOD), mitochondria membrane potential (MMP) and Glutathione peroxidase (GSH-Px). It up-regulated malondialdehyde (MDA) production and intracellular reactive oxygen species (ROS). In addition, phosphoinositide 3 kinase/protein kinase B/Glycogen synthase kinase3β (PI3K/Akt/GSK3β) and mitogen activated protein kinase (MAPK) were also involved in this process. We found that pre-treatment with quercetin can inhibited OA-induced the hyperphosphorylation of tau protein and oxidative stress. Moreover, pre-treatment with quercetin not only inhibited OA-induced apoptosis via the reduction of Bax, and up-regulation of cleaved caspase 3, but also via the inhibition of PI3K/Akt/GSK3β, MAPKs and activation of NF-κB p65. Our findings suggest the therapeutic potential of quercetin to treat AD. PMID:27050422

  5. Modulating the p66shc signaling pathway with protocatechuic acid protects the intestine from ischemia-reperfusion injury and alleviates secondary liver damage.

    PubMed

    Ma, Lingfei; Wang, Guangzhi; Chen, Zhao; Li, Zhenlu; Yao, Jihong; Zhao, Haidong; Wang, Shu; Ma, Zhenhai; Chang, Hong; Tian, Xiaofeng

    2014-01-01

    Intestinal ischemia-reperfusion (I/R) injury is a serious clinical pathophysiological process that may result in acute local intestine and remote liver injury. Protocatechuic acid (PCA), which has been widely studied as a polyphenolic compound, induces expression of antioxidative genes that combat oxidative stress and cell apoptosis. In this study, we investigated the effect of PCA pretreatment for protecting intestinal I/R-induced local intestine and remote liver injury in mice. Intestinal I/R was established by superior mesenteric artery occlusion for 45 min followed by reperfusion for 90 min. After the reperfusion period, PCA pretreatment markedly alleviated intestine and liver injury induced by intestinal I/R as indicated by histological alterations, decreases in serological damage parameters and nuclear factor-kappa B and phospho-foxo3a protein expression levels, and increases in glutathione, glutathione peroxidase, manganese superoxide dismutase protein expression, and Bcl-xL protein expression in the intestine and liver. These parameters were accompanied by PCA-induced adaptor protein p66shc suppression. These results suggest that PCA has a significant protective effect in the intestine and liver following injury induced by intestinal I/R. The protective effect of PCA may be attributed to the suppression of p66shc and the regulation of p66shc-related antioxidative and antiapoptotic factors.

  6. Gardenia jasminoides extracts and gallic acid inhibit lipopolysaccharide-induced inflammation by suppression of JNK2/1 signaling pathways in BV-2 cells

    PubMed Central

    Lin, Wen-Hung; Kuo, Heng-Hung; Ho, Li-Hsing; Tseng, Ming-Lang; Siao, An-Ci; Hung, Chang-Tsen; Jeng, Kee-Ching; Hou, Chien-Wei

    2015-01-01

    Objective(s): Gardenia jasminoides Ellis (GJ, Cape Jasmine Fruit, Zhi Zi) has been traditionally used for the treatment of infectious hepatitis, aphthous ulcer, and trauma; however, the direct evidence is lacking. Materials and Methods: We investigated the effect of the GJ extract (GJ) and gallic acid (GA) on lipopolysaccharide (LPS) induced inflammation of BV-2 microglial cells and acute liver injury in Sprague-Dawley (SD) rats. Results: Our results showed that the GJ extract and GA reduced LPS-induced nitric oxide (NO), interleukin (IL)-1, IL-6, reactive oxygen species (ROS), and prostaglandin (PGE2) production in BV-2 cells. The GJ extract and GA significantly decreased serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in LPS-treated rats. Furthermore, the water extract, but not the ethanol extract, of the GJ dose-dependently inhibited LPS-induced JNK2/1 and slightly p38 mitogen-activated protein kinases (MAPK), and cyclooxygenase-2 (COX-2) expression in BV-2 cells. Conclusion: Taken together, these results indicate that the protective mechanism of the GJ extract involves an antioxidant effect and inhibition of JNK2/1 MAP kinase and COX-2 expressions in LPS-induced inflammation of BV-2 cells. PMID:26221479

  7. Quercetin Protects against Okadaic Acid-Induced Injury via MAPK and PI3K/Akt/GSK3β Signaling Pathways in HT22 Hippocampal Neurons

    PubMed Central

    Li, Sheng; Zhou, Yue; Shen, Xiu-Yin; He, Feng; Xu, Jie; Wang, Hua-Qiao

    2016-01-01

    Increasing evidence shows that oxidative stress and the hyperphosphorylation of tau protein play essential roles in the progression of Alzheimer’s disease (AD). Quercetin is a major flavonoid that has anti-oxidant, anti-cancer and anti-inflammatory properties. We investigated the neuroprotective effects of quercetin to HT22 cells (a cell line from mouse hippocampal neurons). We found that Okadaic acid (OA) induced the hyperphosphorylation of tau protein at Ser199, Ser396, Thr205, and Thr231 and produced oxidative stress to the HT22 cells. The oxidative stress suppressed the cell viability and decreased the levels of lactate dehydrogenase (LDH), superoxide dismutase (SOD), mitochondria membrane potential (MMP) and Glutathione peroxidase (GSH-Px). It up-regulated malondialdehyde (MDA) production and intracellular reactive oxygen species (ROS). In addition, phosphoinositide 3 kinase/protein kinase B/Glycogen synthase kinase3β (PI3K/Akt/GSK3β) and mitogen activated protein kinase (MAPK) were also involved in this process. We found that pre-treatment with quercetin can inhibited OA-induced the hyperphosphorylation of tau protein and oxidative stress. Moreover, pre-treatment with quercetin not only inhibited OA-induced apoptosis via the reduction of Bax, and up-regulation of cleaved caspase 3, but also via the inhibition of PI3K/Akt/GSK3β, MAPKs and activation of NF-κB p65. Our findings suggest the therapeutic potential of quercetin to treat AD. PMID:27050422

  8. Evolutionary conservation of plant gibberellin signalling pathway components

    PubMed Central

    Vandenbussche, Filip; Fierro, Ana C; Wiedemann, Gertrud; Reski, Ralf; Van Der Straeten, Dominique

    2007-01-01

    Background: Gibberellins (GA) are plant hormones that can regulate germination, elongation growth, and sex determination. They ubiquitously occur in seed plants. The discovery of gibberellin receptors, together with advances in understanding the function of key components of GA signalling in Arabidopsis and rice, reveal a fairly short GA signal transduction route. The pathway essentially consists of GID1 gibberellin receptors that interact with F-box proteins, which in turn regulate degradation of downstream DELLA proteins, suppressors of GA-controlled responses. Results: Arabidopsis sequences of the gibberellin signalling compounds were used to screen databases from a variety of plants, including protists, for homologues, providing indications for the degree of conservation of the pathway. The pathway as such appears completely absent in protists, the moss Physcomitrella patens shares only a limited homology with the Arabidopsis proteins, thus lacking essential characteristics of the classical GA signalling pathway, while the lycophyte Selaginella moellendorffii contains a possible ortholog for each component. The occurrence of classical GA responses can as yet not be linked with the presence of homologues of the signalling pathway. Alignments and display in neighbour joining trees of the GA signalling components confirm the close relationship of gymnosperms, monocotyledonous and dicotyledonous plants, as suggested from previous studies. Conclusion: Homologues of the GA-signalling pathway were mainly found in vascular plants. The GA signalling system may have its evolutionary molecular onset in Physcomitrella patens, where GAs at higher concentrations affect gravitropism and elongation growth. PMID:18047669

  9. Targeting the Notch signaling pathway in cancer therapeutics

    PubMed Central

    Guo, Huajiao; Lu, Yi; Wang, Jianhua; Liu, Xia; Keller, Evan T; Liu, Qian; Zhou, Qinghua; Zhang, Jian

    2014-01-01

    Despite advances in surgery, imaging, chemotherapy, and radiotherapy, the poor overall cancer-related death rate remains unacceptable. Novel therapeutic strategies are desperately needed. Nowadays, targeted therapy has become the most promising therapy and a welcome asset to the cancer therapeutic arena. There is a large body of evidence demonstrating that the Notch signaling pathway is critically involved in the pathobiology of a variety of malignancies. In this review, we provide an overview of emerging data, highlight the mechanism of the Notch signaling pathway in the development of a wide range of cancers, and summarize recent progress in therapeutic targeting of the Notch signaling pathway. PMID:26767041

  10. 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.

  11. Neurotrophin signalling pathways regulating neuronal apoptosis.

    PubMed

    Miller, F D; Kaplan, D R

    2001-07-01

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

  12. Tight Junction–Associated Signaling Pathways Modulate Cell Proliferation in Uveal Melanoma

    PubMed Central

    Jayagopal, Ashwath; Yang, Jin-Long; Haselton, Frederick R.; Chang, Min S.

    2011-01-01

    Purpose. To investigate the role of tight junction (TJ)–associated signaling pathways in the proliferation of uveal melanoma. Methods. Human uveal melanoma cell lines overexpressing the TJ molecule blood vessel epicardial substance (Bves) were generated. The effects of Bves overexpression on TJ protein expression, cell proliferation, and cell cycle distribution were quantified. In addition, localization and transcription activity of the TJ-associated protein ZO-1–associated nucleic acid binding protein (ZONAB) were evaluated using immunofluorescence and bioluminescence reporter assays to study the involvement of Bves signaling in cell proliferation-associated pathways. Results. Bves overexpression in uveal melanoma cell lines resulted in increased expression of the TJ proteins occludin and ZO-1, reduced cell proliferation, and increased sequestration of ZONAB at TJs and reduced ZONAB transcriptional activity. Conclusions. TJ proteins are present in uveal melanoma, and TJ-associated signaling pathways modulate cell signaling pathways relevant to proliferation in uveal melanoma. PMID:20861479

  13. An arachidonic acid-preferring acyl-CoA synthetase is a hormone-dependent and obligatory protein in the signal transduction pathway of steroidogenic hormones.

    PubMed

    Cornejo Maciel, Fabiana; Maloberti, Paula; Neuman, Isabel; Cano, Florencia; Castilla, Rocío; Castillo, Fernanda; Paz, Cristina; Podestá, Ernesto J

    2005-06-01

    We have described that, in adrenal and Leydig cells, the hormonal regulation of free arachidonic acid (AA) concentration is mediated by the concerted action of two enzymes: an acyl-CoA thioesterase (MTE-I or ARTISt) and an acyl-CoA synthetase (ACS4). In this study we analyzed the potential regulation of these proteins by hormonal action in steroidogenic cells. We demonstrated that ACS4 is rapidly induced by adrenocorticotropin (ACTH) and cAMP in Y1 adrenocortical cells. The hormone and its second messenger increased ACS4 protein levels in a time and concentration dependent way. Maximal concentration of ACTH (10 mIU/ml) produced a significant effect after 15 min of treatment and exerted the highest increase (3-fold) after 30 min. Moreover, (35)S-methionine incorporation showed that the increase in ACS4 protein levels is due to an increase in the de novo synthesis of the protein. On the contrary MTE-I protein levels in Y1 and MA-10 cells did not change after steroidogenic stimuli. In contrast with the effect observed on protein levels, stimulation of both cell lines did not change ACS4 RNA levels during the first hour of treatment, indicating that the effect of both stimuli is exerted at the level of ACS4 protein synthesis.StAR protein induction has a key role on the activation of steroidogenesis since this protein increases the rate of the limiting step of the whole process. In agreement with the fact that the inhibition of ACS4 activity by triacsin C blocks cAMP-stimulated progesterone production by MA-10 Leydig cells, here we demonstrated that ACS4 inhibition also reduces StAR protein levels. Moreover, exogenous AA was able to overcome the effect of triacsin C on both events, StAR induction and steroidogenesis. These results were confirmed by experiments using ACS4-targeted siRNA which result in a reduction in both ACS4 and StAR protein levels. The concomitant decrease in steroid production was overcome by the addition of AA to the knocked-out cells. In summary

  14. Intricacies of hedgehog signaling pathways: A perspective in tumorigenesis

    SciTech Connect

    Kar, Swayamsiddha; Deb, Moonmoon; Sengupta, Dipta; Shilpi, Arunima; Bhutia, Sujit Kumar; Patra, Samir Kumar

    2012-10-01

    The hedgehog (HH) signaling pathway is a crucial negotiator of developmental proceedings in the embryo governing a diverse array of processes including cell proliferation, differentiation, and tissue patterning. The overall activity of the pathway is significantly curtailed after embryogenesis as well as in adults, yet it retains many of its functional capacities. However, aberration in HH signaling mediates the initiation, proliferation and continued sustenance of malignancy in different tissues to varying degrees through different mechanisms. In this review, we provide an overview of the role of constitutively active aberrant HH signaling pathway in different types of human cancer and the underlying molecular and genetic mechanisms that drive tumorigenesis in that particular tissue. An insight into the various modes of anomalous HH signaling in different organs will provide a comprehensive knowledge of the pathway in these tissues and open a window for individually tailored, tissue-specific therapeutic interventions. The synergistic cross talking of HH pathway with many other regulatory molecules and developmentally inclined signaling pathways may offer many avenues for pharmacological advances. Understanding the molecular basis of abnormal HH signaling in cancer will provide an opportunity to inhibit the deregulated pathway in many aggressive and therapeutically challenging cancers where promising options are not available.

  15. SPIKE: a database of highly curated human signaling pathways.

    PubMed

    Paz, Arnon; Brownstein, Zippora; Ber, Yaara; Bialik, Shani; David, Eyal; Sagir, Dorit; Ulitsky, Igor; Elkon, Ran; Kimchi, Adi; Avraham, Karen B; Shiloh, Yosef; Shamir, Ron

    2011-01-01

    The rapid accumulation of knowledge on biological signaling pathways and their regulatory mechanisms has highlighted the need for specific repositories that can store, organize and allow retrieval of pathway information in a way that will be useful for the research community. SPIKE (Signaling Pathways Integrated Knowledge Engine; http://www.cs.tau.ac.il/&~spike/) is a database for achieving this goal, containing highly curated interactions for particular human pathways, along with literature-referenced information on the nature of each interaction. To make database population and pathway comprehension straightforward, a simple yet informative data model is used, and pathways are laid out as maps that reflect the curator’s understanding and make the utilization of the pathways easy. The database currently focuses primarily on pathways describing DNA damage response, cell cycle, programmed cell death and hearing related pathways. Pathways are regularly updated, and additional pathways are gradually added. The complete database and the individual maps are freely exportable in several formats. The database is accompanied by a stand-alone software tool for analysis and dynamic visualization of pathways.

  16. Apoptosis of HL-60 human leukemia cells induced by Asiatic acid through modulation of B-cell lymphoma 2 family proteins and the mitogen-activated protein kinase signaling pathway.

    PubMed

    Wu, Qiuling; Lv, Tingting; Chen, Yan; Wen, Lu; Zhang, Junli; Jiang, Xudong; Liu, Fang

    2015-07-01

    The toxicities of conventional chemotherapeutic agents to normal cells restrict their dosage and clinical efficacy in acute leukemia; therefore, it is important to develop novel chemotherapeutics, including natural products, which selectively target cancer-specific pathways. The present study aimed to explore the effect of the chemopreventive agent asiatic acid (AA) on the proliferation and apoptotic rate of the leukemia cell line HL-60 and investigated the mechanisms underlying its anti-tumor activity. The effect of AA on the proliferation of HL-60 cells was evaluated using the MTT assay. Annexin V-fluorescein isothiocyanate/propidium iodide double staining followed by flow cytometric analysis as well as Hoechst 33258 staining were used to analyze the apoptotic rate of the cells. Furthermore, changes of survivin, B-cell lymphoma 2 (Bcl-2), myeloid cell leukemia 1 (Mcl-1), extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 expressions were detected by western blot analysis. AA blocked the growth of HL-60 cells in a dose- and time-dependent manner. The IC50-value of AA on HL-60 cells was 46.67 ± 5.08 µmol/l for 24 h. AA induced apoptosis in a dose-dependent manner, which was inhibited in the presence of Z-DEVD-FMK, a specific inhibitor of caspase. The anti-apoptotic proteins Bcl-2, Mcl-1 and survivin were downregulated by AA in a dose-dependent manner. Concurrently, AA inhibited ERK and p38 phosphorylation in a dose-dependent manner, while JNK phosphorylation was not affected. In conclusion, the present study indicated that the p38 and ERK pathways, as well as modulation of Bcl-2 family and survivin proteins were key regulators of apoptosis induced in HL-60 cells in response to AA.

  17. UV signaling pathways within the skin

    PubMed Central

    Chen, Hongxiang; Weng, Qing Yu; Fisher, David E.

    2014-01-01

    The effects of UVR on the skin include tanning, carcinogenesis, immunomodulation, and synthesis of vitamin D, among others. Melanocortin 1 receptor polymorphisms correlate with skin pigmentation, UV sensitivity, and skin cancer risk. This article reviews pathways through which UVR induces cutaneous stress and the pigmentation response. Modulators of the UV tanning pathway include sunscreen agents, MC1R activators, adenylate cyclase activators, phosphodiesterase 4D3 inhibitors, T oligos, and MITF regulators such as histone deacetylase (HDAC)-inhibitors. UVR, as one of the most ubiquitous carcinogens, represents both a challenge and enormous opportunity in skin cancer prevention. PMID:24759085

  18. Cherry Valley Ducks Mitochondrial Antiviral-Signaling Protein-Mediated Signaling Pathway and Antiviral Activity Research

    PubMed Central

    Li, Ning; Hong, Tianqi; Li, Rong; Wang, Yao; Guo, Mengjiao; Cao, Zongxi; Cai, Yumei; Liu, Sidang; Chai, Tongjie; Wei, Liangmeng

    2016-01-01

    Mitochondrial antiviral-signaling protein (MAVS), an adaptor protein of retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs)-mediated signal pathway, is involved in innate immunity. In this study, Cherry Valley duck MAVS (duMAVS) was cloned from the spleen and analyzed. duMAVS was determined to have a caspase activation and recruitment domain at N-terminal, followed by a proline-rich domain and a transmembrane domain at C-terminal. Quantitative real-time PCR indicated that duMAVS was expressed in all tissues tested across a broad expression spectrum. The expression of duMAVS was significantly upregulated after infection with duck Tembusu virus (DTMUV). Overexpression of duMAVS could drive the activation of interferon (IFN)-β, nuclear factor-κB, interferon regulatory factor 7, and many downstream factors (such as Mx, PKR, OAS, and IL-8) in duck embryo fibroblast cells. What is more, RNA interference further confirmed that duMAVS was an important adaptor for IFN-β activation. The antiviral assay showed that duMAVS could suppress the various viral replications (DTMUV, novel reovirus, and duck plague virus) at early stages of infection. Overall, these results showed that the main signal pathway mediated by duMAVS and it had a broad-spectrum antiviral ability. This research will be helpful to better understanding the innate immune system of ducks. PMID:27708647

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

    PubMed

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

    2009-01-01

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

  20. Acetaminophen-induced liver injury: Implications for temporal homeostasis of lipid metabolism and eicosanoid signaling pathway.

    PubMed

    Suciu, Maria; Gruia, Alexandra T; Nica, Dragos V; Azghadi, Seyed M R; Mic, Ani A; Mic, Felix A

    2015-12-01

    Acetaminophen is a commonly used drug that induces serious hepatotoxicity when overdosed, leading to increased levels of serum aminotransferases. However, little knowledge exists linking acetaminophen to liver free fatty acids and the eicosanoid-mediated signaling pathway. To this end, adult NMRI mice injected with a dose of 400 mg/kg acetaminophen were monitored for one week post-treatment. Consistent changes were observed in serum transaminases, profile of hepatic free fatty acids, expression of cyclooxygenase, elongase, lipogenesis, and lipolysis genes; as well as in expression patterns of cyclooxygenase-1 and -2 in the liver. Both linoleic acid and arachidonic acid--substrates in eicosanoid biosynthesis--were significantly influenced by overdose, and the latter peaked first among the free fatty acids examined here. There was a close similarity between the temporal dynamics of linoleic acid and aspartate aminotransferases. Moreover, serum transaminases were reduced by cyclooxygenase-2 inhibitors, but not by cyclooxygenase-1 inhibitors. Our results hence attest to the hazard of acetaminophen overdose on the temporal homeostasis of hepatic concentrations of free fatty acids and expression of key genes underlying liver lipid metabolism. There is also evidence for activation of a cyclooxygenase-mediated signaling pathway, especially the cyclooxygenase 2-prostanoid pathway, during acetaminophen-induced liver injury. Therefore, the results of the present study should provide valuable information to a wide audience, working to understand the health hazard of this drug and the implications of the eicosanoid signaling pathway in liver pathophysiology.

  1. Salvianolic acid B improves the disruption of high glucose-mediated brain microvascular endothelial cells via the ROS/HIF-1α/VEGF and miR-200b/VEGF signaling pathways.

    PubMed

    Yang, Ming-Chao; You, Fu-Li; Wang, Zhe; Liu, Xiang-Nan; Wang, Yan-Feng

    2016-09-01

    The study investigated the roles and mechanisms of Salvianolic acid B (Sal B) on permeability of rat brain microvascular endothelial cells (RBMECs) exposed to high glucose. The results demonstrated that Sal B greatly up-regulated the expression of tight junction (TJ) proteins and decreased the permeability of RBMECs compared with the control group. And the increase of reactive oxidative species (ROS) production, the upregulation of hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF) protein induced by high glucose were antagonized by Sal B. In addition, a great decrease of microRNA-200b (miR-200b) was observed in the RBMECs under high-glucose condition, which was significantly increased by Sal B pretreatment. And overexpression of miR-200b markedly attenuated the RBMECs permeability and inhibited the expression of VEGF protein by targeting with 3'-UTR of its mRNA. This led to the conclusion that Sal B-mediated improvement of blood-brain barrier dysfunction induced by high-glucose is related to the ROS/HIF-1α/VEGF and miR-200b/VEGF signaling pathways.

  2. ER-Dependent Ca++-mediated Cytosolic ROS as an Effector for Induction of Mitochondrial Apoptotic and ATM-JNK Signal Pathways in Gallic Acid-treated Human Oral Cancer Cells.

    PubMed

    Lu, Yao-Cheng; Lin, Meng-Liang; Su, Hong-Lin; Chen, Shih-Shun

    2016-02-01

    Release of calcium (Ca(++)) from the endoplasmic reticulum (ER) has been proposed to be involved in induction of apoptosis by oxidative stress. Using inhibitor of ER Ca(++) release dantrolene and inhibitor of mitochondrial Ca(++) uptake Ru-360, we demonstrated that Ca(++) release from the ER was associated with generation of reactive oxygen species (ROS), loss of mitochondrial membrane potential, and apoptosis of human oral cancer (OC) cells induced by gallic acid (GA). Small interfering RNA-mediated suppression of protein kinase RNA-like endoplasmic reticulum kinase inhibited tunicamycin-induced induction of 78 kDa glucose-regulated protein, C/EBP homologous protein, pro-caspase-12 cleavage, cytosolic Ca(++) increase and apoptosis, but did not attenuate the increase in cytosolic Ca(++) level and apoptosis induced by GA. Ataxia telangiectasia mutated (ATM)-mediated c-Jun N-terminal kinase (JNK) phosphorylation and apoptosis by GA was blocked by dantrolene. The specificity of ROS-mediated ATM-JNK activation was confirmed by treatment with N-acetylcysteine, a ROS scavenger. Blockade of ATM activation by specific inhibitor KU55933, short hairpin RNA, or kinase-dead ATM overexpression suppressed JNK phosphorylation but did not completely inhibit cytosolic ROS production, mitochondrial cytochrome c release, pro-caspase-3 cleavage, and apoptosis induced by GA. Taken together, these results indicate that GA induces OC cell apoptosis by inducing the activation of mitochondrial apoptotic and ATM-JNK signal pathways, likely through ER Ca(++)-mediated ROS production. PMID:26851027

  3. ER-Dependent Ca++-mediated Cytosolic ROS as an Effector for Induction of Mitochondrial Apoptotic and ATM-JNK Signal Pathways in Gallic Acid-treated Human Oral Cancer Cells.

    PubMed

    Lu, Yao-Cheng; Lin, Meng-Liang; Su, Hong-Lin; Chen, Shih-Shun

    2016-02-01

    Release of calcium (Ca(++)) from the endoplasmic reticulum (ER) has been proposed to be involved in induction of apoptosis by oxidative stress. Using inhibitor of ER Ca(++) release dantrolene and inhibitor of mitochondrial Ca(++) uptake Ru-360, we demonstrated that Ca(++) release from the ER was associated with generation of reactive oxygen species (ROS), loss of mitochondrial membrane potential, and apoptosis of human oral cancer (OC) cells induced by gallic acid (GA). Small interfering RNA-mediated suppression of protein kinase RNA-like endoplasmic reticulum kinase inhibited tunicamycin-induced induction of 78 kDa glucose-regulated protein, C/EBP homologous protein, pro-caspase-12 cleavage, cytosolic Ca(++) increase and apoptosis, but did not attenuate the increase in cytosolic Ca(++) level and apoptosis induced by GA. Ataxia telangiectasia mutated (ATM)-mediated c-Jun N-terminal kinase (JNK) phosphorylation and apoptosis by GA was blocked by dantrolene. The specificity of ROS-mediated ATM-JNK activation was confirmed by treatment with N-acetylcysteine, a ROS scavenger. Blockade of ATM activation by specific inhibitor KU55933, short hairpin RNA, or kinase-dead ATM overexpression suppressed JNK phosphorylation but did not completely inhibit cytosolic ROS production, mitochondrial cytochrome c release, pro-caspase-3 cleavage, and apoptosis induced by GA. Taken together, these results indicate that GA induces OC cell apoptosis by inducing the activation of mitochondrial apoptotic and ATM-JNK signal pathways, likely through ER Ca(++)-mediated ROS production.

  4. UNDERSTANDING PATHWAYS OF TOXICITY: MAKING SENSE OF CHANGING SIGNALS

    EPA Science Inventory

    Title:
    Understanding Pathways of Toxicity: Making sense of changing signals
    Authors & affiliations:
    Sid Hunter, Maria Blanton, Edward Karoly, Ellen Rogers, Leonard Mole, Phillip Hartig, James Andrews. Reproductive Toxicology Division, National Health and Environmental Ef...

  5. Linear effects models of signaling pathways from combinatorial perturbation data

    PubMed Central

    Szczurek, Ewa; Beerenwinkel, Niko

    2016-01-01

    Motivation: Perturbations constitute the central means to study signaling pathways. Interrupting components of the pathway and analyzing observed effects of those interruptions can give insight into unknown connections within the signaling pathway itself, as well as the link from the pathway to the effects. Different pathway components may have different individual contributions to the measured perturbation effects, such as gene expression changes. Those effects will be observed in combination when the pathway components are perturbed. Extant approaches focus either on the reconstruction of pathway structure or on resolving how the pathway components control the downstream effects. Results: Here, we propose a linear effects model, which can be applied to solve both these problems from combinatorial perturbation data. We use simulated data to demonstrate the accuracy of learning the pathway structure as well as estimation of the individual contributions of pathway components to the perturbation effects. The practical utility of our approach is illustrated by an application to perturbations of the mitogen-activated protein kinase pathway in Saccharomyces cerevisiae. Availability and Implementation: lem is available as a R package at http://www.mimuw.edu.pl/∼szczurek/lem. Contact: szczurek@mimuw.edu.pl; niko.beerenwinkel@bsse.ethz.ch Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27307630

  6. Cardioprotective actions of Notch1 against myocardial infarction via LKB1-dependent AMPK signaling pathway.

    PubMed

    Yang, Hui; Sun, Wanqing; Quan, Nanhu; Wang, Lin; Chu, Dongyang; Cates, Courtney; Liu, Quan; Zheng, Yang; Li, Ji

    2016-05-15

    AMP-activated protein kinase (AMPK) signaling pathway plays a pivotal role in intracellular adaptation to energy stress during myocardial ischemia. Notch1 signaling in the adult myocardium is also activated in response to ischemic stress. However, the relationship between Notch1 and AMPK signaling pathways during ischemia remains unclear. We hypothesize that Notch1 as an adaptive signaling pathway protects the heart from ischemic injury via modulating the cardioprotective AMPK signaling pathway. C57BL/6J mice were subjected to an in vivo ligation of left anterior descending coronary artery and the hearts from C57BL/6J mice were subjected to an ex vivo globe ischemia and reperfusion in the Langendorff perfusion system. The Notch1 signaling was activated during myocardial ischemia. A Notch1 γ-secretase inhibitor, dibenzazepine (DBZ), was intraperitoneally injected into mice to inhibit Notch1 signaling pathway by ischemia. The inhibition of Notch1 signaling by DBZ significantly augmented cardiac dysfunctions caused by myocardial infarction. Intriguingly, DBZ treatment also significantly blunted the activation of AMPK signaling pathway. The immunoprecipitation experiments demonstrated that an interaction between Notch1 and liver kinase beta1 (LKB1) modulated AMPK activation during myocardial ischemia. Furthermore, a ligand of Notch1 Jagged1 can significantly reduce cardiac damage caused by ischemia via activation of AMPK signaling pathway and modulation of glucose oxidation and fatty acid oxidation during ischemia and reperfusion. But Jagged1 did not have any cardioprotections on AMPK kinase dead transgenic hearts. Taken together, the results indicate that the cardioprotective effect of Notch1 against ischemic damage is mediated by AMPK signaling via an interaction with upstream LKB1.

  7. Arrestins: ubiquitous regulators of cellular signaling pathways.

    PubMed

    Gurevich, Eugenia V; Gurevich, Vsevolod V

    2006-01-01

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

  8. Role of Hedgehog Signaling Pathway in NASH

    PubMed Central

    Verdelho Machado, Mariana; Diehl, Anna Mae

    2016-01-01

    Non-alcoholic fatty liver disease (NAFLD) is the number one cause of chronic liver disease in the Western world. Although only a minority of patients will ultimately develop end-stage liver disease, it is not yet possible to efficiently predict who will progress and, most importantly, effective treatments are still unavailable. Better understanding of the pathophysiology of this disease is necessary to improve the clinical management of NAFLD patients. Epidemiological data indicate that NAFLD prognosis is determined by an individual’s response to lipotoxic injury, rather than either the severity of exposure to lipotoxins, or the intensity of liver injury. The liver responds to injury with a synchronized wound-healing response. When this response is abnormal, it leads to pathological scarring, resulting in progressive fibrosis and cirrhosis, rather than repair. The hedgehog pathway is a crucial player in the wound-healing response. In this review, we summarize the pre-clinical and clinical evidence, which demonstrate the role of hedgehog pathway dysregulation in NAFLD pathogenesis, and the preliminary data that place the hedgehog pathway as a potential target for the treatment of this disease. PMID:27258259

  9. Modeling Protein Expression and Protein Signaling Pathways

    PubMed Central

    Telesca, Donatello; Müller, Peter; Kornblau, Steven M.; Suchard, Marc A.; Ji, Yuan

    2015-01-01

    High-throughput functional proteomic technologies provide a way to quantify the expression of proteins of interest. Statistical inference centers on identifying the activation state of proteins and their patterns of molecular interaction formalized as dependence structure. Inference on dependence structure is particularly important when proteins are selected because they are part of a common molecular pathway. In that case, inference on dependence structure reveals properties of the underlying pathway. We propose a probability model that represents molecular interactions at the level of hidden binary latent variables that can be interpreted as indicators for active versus inactive states of the proteins. The proposed approach exploits available expert knowledge about the target pathway to define an informative prior on the hidden conditional dependence structure. An important feature of this prior is that it provides an instrument to explicitly anchor the model space to a set of interactions of interest, favoring a local search approach to model determination. We apply our model to reverse-phase protein array data from a study on acute myeloid leukemia. Our inference identifies relevant subpathways in relation to the unfolding of the biological process under study. PMID:26246646

  10. A common response to common danger? Comparison of animal and plant signaling pathways involved in cadmium sensing.

    PubMed

    Chmielowska-Bąk, Jagna; Deckert, Joanna

    2012-12-01

    Exposure to cadmium results in disturbances in cell homeostasis in all living organisms. The first response to stress factors, including cadmium, is activation of signal transduction pathways that mobilize cell defense mechanisms. The aim of this review is a comparison between the signaling network triggered by Cd in plants and animals. Despite differences in the structure and physiology of plant and animal cells, their cadmium signal transduction pathways share many common elements. These elements include signaling molecules such as ROS, Ca(2+) and NO, the involvement of phospholipase C, mitogen-activated protein kinase cascades, and activation of transcription factors. Undoubtedly, both animals and plants also possess specific signaling pathways. In case of animals, Wnt/β-catenin, sonic hedgehog and oestorgen signaling are engaged in the transduction of cadmium signal. Plant specific signal transduction pathways include signaling mediated by plant hormones. The role of ethylene and jasmonic, salicylic and abscisic acid in plant response to cadmium is also discussed.

  11. Sonic Hedgehog Signalling Pathway and Ameloblastoma - A Review.

    PubMed

    Mishra, Pallavi; Panda, Abikshyeet; Bandyopadhyay, Alokenath; Kumar, Harish; Mohiddin, Gouse

    2015-11-01

    Ameloblastoma is a benign but aggressive odontogenic neoplasm arising from odontogenic epithelium. Many theories have been proposed to explain the pathogenesis of ameloblatoma. Numerous signalling pathways have been implicated to be associated in the development and progression of this neoplasm. Studies have found association of various signalling molecules of Sonic Hedgehog Pathway, namely SHH, PTCH1, SMO, Gli 1, Gli 2, Gli 3, with ameloblastoma. Knowledge about this pathway will help us to understand the nature and behaviour of this neoplasm. This will open the door towards new treatment modalities. PMID:26674664

  12. Sonic Hedgehog Signalling Pathway and Ameloblastoma – A Review

    PubMed Central

    Mishra, Pallavi; Bandyopadhyay, Alokenath; Kumar, Harish; Mohiddin, Gouse

    2015-01-01

    Ameloblastoma is a benign but aggressive odontogenic neoplasm arising from odontogenic epithelium. Many theories have been proposed to explain the pathogenesis of ameloblatoma. Numerous signalling pathways have been implicated to be associated in the development and progression of this neoplasm. Studies have found association of various signalling molecules of Sonic Hedgehog Pathway, namely SHH, PTCH1, SMO, Gli 1, Gli 2, Gli 3, with ameloblastoma. Knowledge about this pathway will help us to understand the nature and behaviour of this neoplasm. This will open the door towards new treatment modalities. PMID:26674664

  13. Humic acid in drinking well water induces inflammation through reactive oxygen species generation and activation of nuclear factor-κB/activator protein-1 signaling pathways: A possible role in atherosclerosis

    SciTech Connect

    Hseu, You-Cheng; Senthil Kumar, K.J.; Chen, Chih-Sheng; Cho, Hsin-Ju; Lin, Shu-Wei; Shen, Pei-Chun; Lin, Cheng-Wen; Lu, Fung-Jou; Yang, Hsin-Ling

    2014-01-15

    Humic acid (HA) has been implicated as one of the etiological factors in the peripheral vasculopathy of blackfoot disease (BFD) in Taiwan. However, the underlying pathophysiological mechanisms of BFD are not well defined. In this study, we used an in vitro and in vivo model, in which HA (25–200 μg/mL) activated macrophages to produce pro-inflammatory molecules by activating their transcriptional factors. HA exposure induced NO and PGE{sub 2} production followed by induction of iNOS and COX-2 through NF-κB/AP-1 transactivation in macrophages. In addition, the production of TNF-α and IL-1β was significantly increased by HA. Moreover, HA-induced iNOS and COX-2 expression were down-regulated by the NF-κB and AP-1 inhibitors pyrrolidine dithiocarbamate (PDTC) and Tanshinone, respectively. Furthermore, generations of ROS and nitrotyrosine, as well as activation of the AKT and MAPKs signaling cascades were observed after HA exposure. Specifically, HA-induced NF-κB activation was mediated by ROS and AKT, and that HA-induced AP-1 activation was mediated by JNK and ERK. Notably, HA-mediated AKT, JNK, and ERK activation was ROS-independent. The inflammatory potential of HA was correlated with increased expression of HO-1 and Nrf2. Furthermore, an in vivo study confirms that mice exposed to HA, the serum levels of TNF-α and IL-1β was significantly increased in a dose-dependent manner. This report marks the first confirmation that environmental exposure of HA induces inflammation in macrophages, which may be one of the main causes of early atherogenesis in blackfoot disease. - Highlights: • Humic acid (HA) induce pro-inflammatory cytokines and mediators in macrophages. • HA-induced inflammation is mediated by ROS and NF-κB/AP-1 signaling pathways. • The inflammatory potential of HA correlated with activation of Nrf2/HO-1 genes. • HA exposure to mice increased pro-inflammatory cytokines production in vivo. • HA may be one of the main causes of early

  14. Acylcarnitines activate pro-inflammatory signaling pathways

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Incomplete beta-oxidation of fatty acids in mitochondria is a feature of insulin resistance and type 2 diabetes mellitus (T2DM) and the resulting metabolic by-products, medium- and long-chain acylcarnitines are shown to be elevated. In preliminary studies, mixed isomers of C12- or C14-carnitine act...

  15. Signaling pathway networks mined from human pituitary adenoma proteomics data

    PubMed Central

    2010-01-01

    Background We obtained a series of pituitary adenoma proteomic expression data, including protein-mapping data (111 proteins), comparative proteomic data (56 differentially expressed proteins), and nitroproteomic data (17 nitroproteins). There is a pressing need to clarify the significant signaling pathway networks that derive from those proteins in order to clarify and to better understand the molecular basis of pituitary adenoma pathogenesis and to discover biomarkers. Here, we describe the significant signaling pathway networks that were mined from human pituitary adenoma proteomic data with the Ingenuity pathway analysis system. Methods The Ingenuity pathway analysis system was used to analyze signal pathway networks and canonical pathways from protein-mapping data, comparative proteomic data, adenoma nitroproteomic data, and control nitroproteomic data. A Fisher's exact test was used to test the statistical significance with a significance level of 0.05. Statistical significant results were rationalized within the pituitary adenoma biological system with literature-based bioinformatics analyses. Results For the protein-mapping data, the top pathway networks were related to cancer, cell death, and lipid metabolism; the top canonical toxicity pathways included acute-phase response, oxidative-stress response, oxidative stress, and cell-cycle G2/M transition regulation. For the comparative proteomic data, top pathway networks were related to cancer, endocrine system development and function, and lipid metabolism; the top canonical toxicity pathways included mitochondrial dysfunction, oxidative phosphorylation, oxidative-stress response, and ERK/MAPK signaling. The nitroproteomic data from a pituitary adenoma were related to cancer, cell death, lipid metabolism, and reproductive system disease, and the top canonical toxicity pathways mainly related to p38 MAPK signaling and cell-cycle G2/M transition regulation. Nitroproteins from a pituitary control related to

  16. 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.

  17. 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.

  18. Regulation of the Hippo-YAP pathway by G-protein coupled receptor signaling

    PubMed Central

    Yu, Fa-Xing; Zhao, Bin; Panupinthu, Nattapon; Jewell, Jenna L.; Lian, Ian; Wang, Lloyd H.; Zhao, Jiagang; Yuan, Haixin; Tumaneng, Karen; Li, Hairi; Fu, Xiang-Dong; Mills, Gordon B.; Guan, Kun-Liang

    2012-01-01

    SUMMARY The Hippo pathway is crucial in organ size control and its dysregulation contributes to tumorigenesis. However, upstream signals that regulate the mammalian Hippo pathway have remained elusive. Here we report that the Hippo pathway is regulated by G-protein coupled receptor (GPCR) signaling. Serum-borne lysophosphatidic acid (LPA) and sphingosine 1-phosphophate (S1P) act through G12/13-coupled receptors to inhibit the Hippo pathway kinases Lats1/2 thereby activating YAP and TAZ transcription co-activators, which are oncoproteins repressed by Lats1/2. YAP and TAZ are involved in LPA-induced gene expression, cell migration, and proliferation. In contrast, stimulation of Gs-coupled receptors by glucagon or epinephrine activates Lats1/2 kinase activity, thereby inhibiting YAP function. Thus, GPCR signaling can either activate or inhibit the Hippo-YAP pathway depending on the coupled G-protein. Our study identifies extracellular diffusible signals that modulate the Hippo pathway and also establishes the Hippo-YAP pathway as a critical signaling branch downstream of GPCR. PMID:22863277

  19. Frontier of Epilepsy Research - mTOR signaling pathway

    PubMed Central

    2011-01-01

    Studies of epilepsy have mainly focused on the membrane proteins that control neuronal excitability. Recently, attention has been shifting to intracellular proteins and their interactions, signaling cascades and feedback regulation as they relate to epilepsy. The mTOR (mammalian target of rapamycin) signal transduction pathway, especially, has been suggested to play an important role in this regard. These pathways are involved in major physiological processes as well as in numerous pathological conditions. Here, involvement of the mTOR pathway in epilepsy will be reviewed by presenting; an overview of the pathway, a brief description of key signaling molecules, a summary of independent reports and possible implications of abnormalities of those molecules in epilepsy, a discussion of the lack of experimental data, and questions raised for the understanding its epileptogenic mechanism. PMID:21467839

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

    SciTech Connect

    Shankaran, Harish; Wiley, H. S.

    2010-12-01

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

  1. Functional roles for myosin 1c in cellular signaling pathways

    PubMed Central

    Bond, Lisa M.; Brandstaetter, Hemma; Kendrick-Jones, John; Buss, Folma

    2013-01-01

    Cellular signaling pathways underlie the transfer of information throughout the cell and to adjoining cells and so govern most critical cellular functions. Increasing evidence points to the molecular motor myosin 1c as a prominent player in many signaling cascades, from the integrin-dependent signaling involved in cell migration to the signaling events underlying insulin resistance. Myosin 1c functions on these pathways both via an important role in regulating lipid raft recycling and also via direct involvement in signaling cascades. This review provides an overview of the functional involvement of myosin 1c in cellular signaling and discusses the possible potential for myosin 1c as a target for drug-based treatments for human diseases. PMID:23022959

  2. IDO⁺ DCs and signalling pathways.

    PubMed

    Wang, Yue; Yang, Bao-Hong; Li, Hui; Cao, Shui; Ren, Xiu-Bao; Yu, Jin-Pu

    2013-03-01

    Dendritic cells (DCs) have traditionally been viewed as constituting an 'information management' system that functions solely to integrate a diverse array of incoming signals, in order to induce immune reactivity. In recent years, however, there has been a shift towards viewing these cells as key regulators in the orchestration of immunological tolerance, with increasing recognition that they are capable of suppressing T-cell responses depending on signalling processes and localised biochemical conditions. Indoleamine 2,3-dioxygenase (IDO) competent (IDO⁺) DCs are a subset of human DCs which are programmed to a tolerogenic state and play a vital role in establishing and maintaining a tumour-suppressing milieu. The expression of IDO in these DCs represents a key mechanism responsible for inducing the tolerogenic state. However, the mechanisms by which IDO becomes dysregulated in this subset of DCs have not yet been described. In this review, the function of IDO⁺ DCs within the cancer-tolerogenic milieu, as well as the signals responsible for expression of IDO in this subset, will be discussed.

  3. Gene Expressions for Signal Transduction under Acidic Conditions

    PubMed Central

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

    2013-01-01

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

  4. Peptide Ligand Structure and I-Aq Binding Avidity Influence T Cell Signaling Pathway Utilization

    PubMed Central

    Myers, Linda K; Cullins, David L; Park, Jeoung-Eun; Yi, Ae-Kyung; Brand, David D; Rosloniec, Edward F; Stuart, John M; Kang, Andrew H

    2015-01-01

    Factors that drive T cells to signal through differing pathways remain unclear. We have shown that an altered peptide ligand (A9) activates T cells to utilize an alternate signaling pathway which is dependent upon FcRγ and Syk. However, it remains unknown whether the affinity of peptide binding to MHC drives this selection. To answer this question we developed a panel of peptides designed so that amino acids interacting with the p6 and p9 predicted MHC binding pockets were altered. Analogs were tested for binding to I-Aq using a competitive binding assay and selected analogs were administered to arthritic mice. Using the collagen-induced arthritis (CIA) model, arthritis severity was correlated with T cell cytokine production and molecular T cell signaling responses. We establish that reduced affinity of interaction with the MHC correlates with T cell signaling through the alternative pathway, leading ultimately to secretion of suppressive cytokine and attenuation of arthritis. PMID:25982319

  5. [Psychiatric implications of PACAP signaling pathway].

    PubMed

    Hashimoto, Hitoshi

    2012-06-01

    Studies on genetically modified mice for investigating the role of pituitary adenylate cyclase-activating polypeptide (PACAP) in the brain have revealed a previously uncharacterized function of this neuropeptidergic signaling in the regulation of psychomotor behaviors. In addition, recent clinical studies investigating single nucleotide polymorphisms and copy number variations in the PACAP and its receptor genes have associated the variations with major psychiatric disorders and stress-dependent mental disorders. Here, I briefly review these recent advances in the field and make this an opportunity to consider future direction of research.

  6. ERβ induces the differentiation of cultured osteoblasts by both Wnt/β-catenin signaling pathway and estrogen signaling pathways

    SciTech Connect

    Yin, Xinhua; Wang, Xiaoyuan; Hu, Xiongke; Chen, Yong; Zeng, Kefeng; Zhang, Hongqi

    2015-07-01

    Although 17β-estradial (E2) is known to stimulate bone formation, the underlying mechanisms are not fully understood. Recent studies have implicated the Wnt/β-catenin pathway as a major signaling cascade in bone biology. The interactions between Wnt/β-catenin signaling pathway and estrogen signaling pathways have been reported in many tissues. In this study, E2 significantly increased the expression of β-catenin by inducing phosphorylations of GSK3β at serine 9. ERβ siRNAs were transfected into MC3T3-E1 cells and revealed that ERβ involved E2-induced osteoblasts proliferation and differentiation via Wnt/β-catenin signaling. The osteoblast differentiation genes (BGP, ALP and OPN) and proliferation related gene (cyclin D1) expression were significantly induced by E2-mediated ERβ. Furthermore immunofluorescence and immunoprecipitation analysis demonstrated that E2 induced the accumulation of β-catenin protein in the nucleus which leads to interaction with T-cell-specific transcription factor/lymphoid enhancer binding factor (TCF/LEF) transcription factors. Taken together, these findings suggest that E2 promotes osteoblastic proliferation and differentiation by inducing proliferation-related and differentiation-related gene expression via ERβ/GSK-3β-dependent Wnt/β-catenin signaling pathway. Our findings provide novel insights into the mechanisms of action of E2 in osteoblastogenesis. - Highlights: • 17β-estradial (E2) promotes GSK3-β phosphorylation. • E2 activates the Wnt/β-catenin signaling pathway. • The Wnt/β-catenin signaling pathway interacts with estrogen signaling pathways. • E2-mediated ER induced osteoblast differentiation and proliferation related genes expression.

  7. Regulatory Cross-Talks and Cascades in Rice Hormone Biosynthesis Pathways Contribute to Stress Signaling.

    PubMed

    Deb, Arindam; Grewal, Rumdeep K; Kundu, Sudip

    2016-01-01

    Crosstalk among different hormone signaling pathways play an important role in modulating plant response to both biotic and abiotic stress. Hormone activity is controlled by its bio-availability, which is again influenced by its biosynthesis. Thus, independent hormone biosynthesis pathways must be regulated and co-ordinated to mount an integrated response. One of the possibilities is to use cis-regulatory elements to orchestrate expression of hormone biosynthesis genes. Analysis of CREs, associated with differentially expressed hormone biosynthesis related genes in rice leaf under Magnaporthe oryzae attack and drought stress enabled us to obtain insights about cross-talk among hormone biosynthesis pathways at the transcriptional level. We identified some master transcription regulators that co-ordinate different hormone biosynthesis pathways under stress. We found that Abscisic acid and Brassinosteroid regulate Cytokinin conjugation; conversely Brassinosteroid biosynthesis is affected by both Abscisic acid and Cytokinin. Jasmonic acid and Ethylene biosynthesis may be modulated by Abscisic acid through DREB transcription factors. Jasmonic acid or Salicylic acid biosynthesis pathways are co-regulated but they are unlikely to influence each others production directly. Thus, multiple hormones may modulate hormone biosynthesis pathways through a complex regulatory network, where biosynthesis of one hormone is affected by several other contributing hormones.

  8. Regulatory Cross-Talks and Cascades in Rice Hormone Biosynthesis Pathways Contribute to Stress Signaling

    PubMed Central

    Deb, Arindam; Grewal, Rumdeep K.; Kundu, Sudip

    2016-01-01

    Crosstalk among different hormone signaling pathways play an important role in modulating plant response to both biotic and abiotic stress. Hormone activity is controlled by its bio-availability, which is again influenced by its biosynthesis. Thus, independent hormone biosynthesis pathways must be regulated and co-ordinated to mount an integrated response. One of the possibilities is to use cis-regulatory elements to orchestrate expression of hormone biosynthesis genes. Analysis of CREs, associated with differentially expressed hormone biosynthesis related genes in rice leaf under Magnaporthe oryzae attack and drought stress enabled us to obtain insights about cross-talk among hormone biosynthesis pathways at the transcriptional level. We identified some master transcription regulators that co-ordinate different hormone biosynthesis pathways under stress. We found that Abscisic acid and Brassinosteroid regulate Cytokinin conjugation; conversely Brassinosteroid biosynthesis is affected by both Abscisic acid and Cytokinin. Jasmonic acid and Ethylene biosynthesis may be modulated by Abscisic acid through DREB transcription factors. Jasmonic acid or Salicylic acid biosynthesis pathways are co-regulated but they are unlikely to influence each others production directly. Thus, multiple hormones may modulate hormone biosynthesis pathways through a complex regulatory network, where biosynthesis of one hormone is affected by several other contributing hormones. PMID:27617021

  9. Regulatory Cross-Talks and Cascades in Rice Hormone Biosynthesis Pathways Contribute to Stress Signaling

    PubMed Central

    Deb, Arindam; Grewal, Rumdeep K.; Kundu, Sudip

    2016-01-01

    Crosstalk among different hormone signaling pathways play an important role in modulating plant response to both biotic and abiotic stress. Hormone activity is controlled by its bio-availability, which is again influenced by its biosynthesis. Thus, independent hormone biosynthesis pathways must be regulated and co-ordinated to mount an integrated response. One of the possibilities is to use cis-regulatory elements to orchestrate expression of hormone biosynthesis genes. Analysis of CREs, associated with differentially expressed hormone biosynthesis related genes in rice leaf under Magnaporthe oryzae attack and drought stress enabled us to obtain insights about cross-talk among hormone biosynthesis pathways at the transcriptional level. We identified some master transcription regulators that co-ordinate different hormone biosynthesis pathways under stress. We found that Abscisic acid and Brassinosteroid regulate Cytokinin conjugation; conversely Brassinosteroid biosynthesis is affected by both Abscisic acid and Cytokinin. Jasmonic acid and Ethylene biosynthesis may be modulated by Abscisic acid through DREB transcription factors. Jasmonic acid or Salicylic acid biosynthesis pathways are co-regulated but they are unlikely to influence each others production directly. Thus, multiple hormones may modulate hormone biosynthesis pathways through a complex regulatory network, where biosynthesis of one hormone is affected by several other contributing hormones.

  10. Regulatory Cross-Talks and Cascades in Rice Hormone Biosynthesis Pathways Contribute to Stress Signaling.

    PubMed

    Deb, Arindam; Grewal, Rumdeep K; Kundu, Sudip

    2016-01-01

    Crosstalk among different hormone signaling pathways play an important role in modulating plant response to both biotic and abiotic stress. Hormone activity is controlled by its bio-availability, which is again influenced by its biosynthesis. Thus, independent hormone biosynthesis pathways must be regulated and co-ordinated to mount an integrated response. One of the possibilities is to use cis-regulatory elements to orchestrate expression of hormone biosynthesis genes. Analysis of CREs, associated with differentially expressed hormone biosynthesis related genes in rice leaf under Magnaporthe oryzae attack and drought stress enabled us to obtain insights about cross-talk among hormone biosynthesis pathways at the transcriptional level. We identified some master transcription regulators that co-ordinate different hormone biosynthesis pathways under stress. We found that Abscisic acid and Brassinosteroid regulate Cytokinin conjugation; conversely Brassinosteroid biosynthesis is affected by both Abscisic acid and Cytokinin. Jasmonic acid and Ethylene biosynthesis may be modulated by Abscisic acid through DREB transcription factors. Jasmonic acid or Salicylic acid biosynthesis pathways are co-regulated but they are unlikely to influence each others production directly. Thus, multiple hormones may modulate hormone biosynthesis pathways through a complex regulatory network, where biosynthesis of one hormone is affected by several other contributing hormones. PMID:27617021

  11. RNase activity of sialic acid-binding lectin from bullfrog eggs drives antitumor effect via the activation of p38 MAPK to caspase-3/7 signaling pathway in human breast cancer cells

    PubMed Central

    Kariya, Yukiko; Tatsuta, Takeo; Sugawara, Shigeki; Kariya, Yoshinobu; Nitta, Kazuo; Hosono, Masahiro

    2016-01-01

    Sialic acid-binding lectin obtained from bullfrog eggs (SBL) induces cell death in cancer cells but not in normal cells. This antitumor effect is mediated through its ribo-nuclease (RNase) activity. However, the underlying molecular mechanisms remain unclear. We found that the p38 mitogen-activated protein kinase (MAPK) signaling pathway was activated when SBL induced cell death in three human breast cancer cell lines: SK-BR-3, MCF-7, and MDA-MB231. The suppression of p38 MAPK phosphorylation by a p38 MAPK inhibitor as well as short interference RNA knockdown of p38 MAPK expression significantly decreased cell death and increased the cell viability of SBL-treated MDA-MB231 cells. H103A, an SBL mutant lacking in RNase activity, showed decreased SBL-induced cell death compared with native SBL. However, the loss of RNase activity of SBL had no effect on its internalization into cells. The H103A mutant also displayed decreased phosphorylation of p38 MAPK. Moreover, SBL promoted caspase-3/7 activation followed by a cleavage of poly (ADP-ribose)-polymerase, whereas the SBL mutant, H103A, lost this ability. The SBL-induced caspase-3/7 activation was suppressed by the p38 MAPK inhibitor, SB203580, as well as pan-caspase inhibitor, zVAD-fmk. In the presence of zVAD-fmk, the SBL-induced cell death was decreased. In addition, the cell viability of SBL-treated MDA-MB231 cells recovered by zVAD-fmk treatment. Taken together, our results suggest that the RNase activity of SBL leads to breast cancer cell death through the activation of p38 MAPK followed by the activation of caspase-3/7. PMID:27513956

  12. Cross-talk in abscisic acid signaling

    NASA Technical Reports Server (NTRS)

    Fedoroff, Nina V.

    2002-01-01

    "Cross-talk" in hormone signaling reflects an organism's ability to integrate different inputs and respond appropriately, a crucial function at the heart of signaling network operation. Abscisic acid (ABA) is a plant hormone involved in bud and seed dormancy, growth regulation, leaf senescence and abscission, stomatal opening, and a variety of plant stress responses. This review summarizes what is known about ABA signaling in the control of stomatal opening and seed dormancy and provides an overview of emerging knowledge about connections between ABA, ethylene, sugar, and auxin synthesis and signaling.

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

    PubMed Central

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

    2009-01-01

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

  14. [Glutamic acid as a universal extracellular signal].

    PubMed

    Yoneda, Yukio

    2015-08-01

    The prevailing view is that both glutamic (Glu) and gamma-aminobutyric (GABA) acids play a role as an amino acid neurotransmitter released from neurons. However, little attention has been paid to the possible expression and functionality of signaling machineries required for amino acidergic neurotransmission in cells other than central neurons. In line with our first demonstration of the presence of Glu receptors outside the brain, in this review I will outline our recent findings accumulated since then on the physiological and pathological significance of neuronal amino acids as an extracellular signal essential for homeostasis in a variety of phenotypic cells. In undifferentiated neural progenitor cells, for instance, functional expression is seen with different signaling machineries used for glutamatergic and GABAergic neurotransmission in neurons. Moreover, Glu plays a role in mechanisms underlying suppression of proliferation for self-replication in undifferentiated mesenchymal stem cells. There is more accumulating evidence for neuronal amino acids playing a role as an extracellular autocrine or paracrine signal commonly used in different phenotypic cells. Evaluation of drugs currently used could be thus beneficial for the efficient prophylaxis and/or the therapy of a variety of diseases relevant to disturbance of amino acid signaling in diverse organs.

  15. A multi-pathway hypothesis for human visual fear signaling

    PubMed Central

    Silverstein, David N.; Ingvar, Martin

    2015-01-01

    A hypothesis is proposed for five visual fear signaling pathways in humans, based on an analysis of anatomical connectivity from primate studies and human functional connectvity and tractography from brain imaging studies. Earlier work has identified possible subcortical and cortical fear pathways known as the “low road” and “high road,” which arrive at the amygdala independently. In addition to a subcortical pathway, we propose four cortical signaling pathways in humans along the visual ventral stream. All four of these traverse through the LGN to the visual cortex (VC) and branching off at the inferior temporal area, with one projection directly to the amygdala; another traversing the orbitofrontal cortex; and two others passing through the parietal and then prefrontal cortex, one excitatory pathway via the ventral-medial area and one regulatory pathway via the ventral-lateral area. These pathways have progressively longer propagation latencies and may have progressively evolved with brain development to take advantage of higher-level processing. Using the anatomical path lengths and latency estimates for each of these five pathways, predictions are made for the relative processing times at selective ROIs and arrival at the amygdala, based on the presentation of a fear-relevant visual stimulus. Partial verification of the temporal dynamics of this hypothesis might be accomplished using experimental MEG analysis. Possible experimental protocols are suggested. PMID:26379513

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

    PubMed Central

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

    2015-01-01

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

  17. Cancer stem cells and signaling pathways in radioresistance

    PubMed Central

    Chang, Lei; Graham, Peter; Hao, Jingli; Ni, Jie; Deng, Junli; Bucci, Joseph; Malouf, David; Gillatt, David; Li, Yong

    2016-01-01

    Radiation therapy (RT) is one of the most important strategies in cancer treatment. Radioresistance (the failure to RT) results in locoregional recurrence and metastasis. Therefore, it is critically important to investigate the mechanisms leading to cancer radioresistance to overcome this problem and increase patients' survival. Currently, the majority of the radioresistance-associated researches have focused on preclinical studies. Although the exact mechanisms of cancer radioresistance have not been fully uncovered, accumulating evidence supports that cancer stem cells (CSCs) and different signaling pathways play important roles in regulating radiation response and radioresistance. Therefore, targeting CSCs or signaling pathway proteins may hold promise for developing novel combination modalities and overcoming radioresistance. The present review focuses on the key evidence of CSC markers and several important signaling pathways in cancer radioresistance and explores innovative approaches for future radiation treatment. PMID:26716904

  18. Signalling pathways involved in the control of sperm cell volume.

    PubMed

    Petrunkina, A M; Harrison, R A P; Tsolova, M; Jebe, E; Töpfer-Petersen, E

    2007-01-01

    The ability to maintain cellular volume is an important general physiological function, which is achieved by specific molecular mechanisms. Hypotonically induced swelling results in the opening of K+ and Cl- ion channels, through which these ions exit with accompanying water loss. This process is known as regulatory volume decrease (RVD). The molecular mechanisms that control the opening of the ion channels in spermatozoa are as yet poorly understood. The present study investigated pathways of osmo-signalling using boar spermatozoa as a model. Spermatozoa were diluted into isotonic and hypotonic Hepes-buffered saline in the presence or absence of effector drugs, and at predetermined intervals volume measurements were performed electronically. Treatment with protein kinase C (PKC) inhibitors staurosporine, bismaleimide I and bismaleimide X led to dose-dependent increases of both isotonic and hypotonic volumes (P<0.05). However, as the isotonic volume was affected more than the hypotonic volume, the kinase inhibitors appeared to improve RVD, whereas activation of PKC with phorbol dibutyrate blocked RVD. The increase in isotonic cell volume induced by bismaleimide X was observed in chloride-containing medium but not in the medium in which chloride was replaced by sulphate, implying that PKC was involved in the control of chloride channel activity, e.g. by closing the channel after volume adjustment. The protein phosphatase PP1/PP2 inhibitors calyculin and okadaic acid increased the isotonic volume only slightly but they greatly increased the relative cell volume and blocked RVD. The activation of RVD processes was found to be cAMP-dependent; incubation with forskolin and papaverine improved volume regulation. Moreover, papaverine was able to overcome the negative effect of protein phosphatase inhibitors. The mechanism of sperm RVD appears to involve (a) alterations in protein phosphorylation/dephosphorylation balance brought about by PKC and PP1 and (b) a c

  19. Triggering signaling pathways using F-actin self-organization

    PubMed Central

    Colin, A.; Bonnemay, L.; Gayrard, C.; Gautier, J.; Gueroui, Z.

    2016-01-01

    The spatiotemporal organization of proteins within cells is essential for cell fate behavior. Although it is known that the cytoskeleton is vital for numerous cellular functions, it remains unclear how cytoskeletal activity can shape and control signaling pathways in space and time throughout the cell cytoplasm. Here we show that F-actin self-organization can trigger signaling pathways by engineering two novel properties of the microfilament self-organization: (1) the confinement of signaling proteins and (2) their scaffolding along actin polymers. Using in vitro reconstitutions of cellular functions, we found that both the confinement of nanoparticle-based signaling platforms powered by F-actin contractility and the scaffolding of engineered signaling proteins along actin microfilaments can drive a signaling switch. Using Ran-dependent microtubule nucleation, we found that F-actin dynamics promotes the robust assembly of microtubules. Our in vitro assay is a first step towards the development of novel bottom-up strategies to decipher the interplay between cytoskeleton spatial organization and signaling pathway activity. PMID:27698406

  20. Dissecting Major Signaling Pathways throughout the Development of Prostate Cancer

    PubMed Central

    da Silva, Henrique B.; Amaral, Eduardo P.; Nolasco, Eduardo L.; de Victo, Nathalia C.; Atique, Rodrigo; Jank, Carina C.; Anschau, Valesca; Zerbini, Luiz F.; Correa, Ricardo G.

    2013-01-01

    Prostate cancer (PCa) is one of the most common malignancies found in males. The development of PCa involves several mutations in prostate epithelial cells, usually linked to developmental changes, such as enhanced resistance to apoptotic death, constitutive proliferation, and, in some cases, to differentiation into an androgen deprivation-resistant phenotype, leading to the appearance of castration-resistant PCa (CRPCa), which leads to a poor prognosis in patients. In this review, we summarize recent findings concerning the main deregulations into signaling pathways that will lead to the development of PCa and/or CRPCa. Key mutations in some pathway molecules are often linked to a higher prevalence of PCa, by directly affecting the respective cascade and, in some cases, by deregulating a cross-talk node or junction along the pathways. We also discuss the possible environmental and nonenvironmental inducers for these mutations, as well as the potential therapeutic strategies targeting these signaling pathways. A better understanding of how some risk factors induce deregulation of these signaling pathways, as well as how these deregulated pathways affect the development of PCa and CRPCa, will further help in the development of new treatments and prevention strategies for this disease. PMID:23738079

  1. Bone biology, signaling pathways, and therapeutic targets for osteoporosis.

    PubMed

    Iñiguez-Ariza, Nicole M; Clarke, Bart L

    2015-10-01

    Major advances have occurred recently in the treatment of osteoporosis in recent years. Most patients are currently treated with bisphosphonates, denosumab, raloxifene, or teriparatide, and in some countries, strontium ranelate. Strontium ranelate and calcitonin have recently had their use restricted due to cardiovascular concerns and malignancy, respectively. The available agents have generally provided excellent options that effectively reduce fracture risk. New targets are being sought based on appreciation of the bone biology and signaling pathways involved in bone formation and resorption. These agents will directly target these signaling pathways, and further expand the options available for treatment of osteoporosis. PMID:26255682

  2. The Hippo Signaling Pathway in Development and Cancer

    PubMed Central

    Pan, Duojia

    2011-01-01

    First discovered in Drosophila, the Hippo signaling pathway is a conserved regulator of organ size. Central to this pathway is a kinase cascade leading from the tumor suppressor Hippo (Mst1 and Mst2 in mammals) to the oncoprotein Yki (YAP and TAZ in mammals), a transcriptional coactivator of target genes involved in cell proliferation and survival. Here, I review recent progress in elucidating the molecular mechanism and physiological function of Hippo signaling in Drosophila and mammals. These studies suggest that the core Hippo kinase cascade integrates multiple upstream inputs, enabling dynamic regulation of tissue homeostasis in animal development and physiology. PMID:20951342

  3. POSTRANSLATIONAL MODIFICATIONS OF P53: UPSTREAM SIGNALING PATHWAYS.

    SciTech Connect

    ANDERSON,C.W.APPELLA,E.

    2003-10-23

    The p53 tumor suppressor is a tetrameric transcription factor that is posttranslational modified at >20 different sites by phosphorylation, acetylation, or sumoylation in response to various cellular stress conditions. Specific posttranslational modifications, or groups of modifications, that result from the activation of different stress-induced signaling pathways are thought to modulate p53 activity to regulate cell fate by inducing cell cycle arrest, apoptosis, or cellular senescence. Here we review recent progress in characterizing the upstream signaling pathways whose activation in response to various genotoxic and non-genotoxic stresses result in p53 posttranslational modifications.

  4. The Notch signaling pathway as a mediator of tumor survival

    PubMed Central

    Pine, Sharon R.

    2013-01-01

    The Notch signaling pathway is evolutionarily conserved and responsible for cell fate determination in the developing embryo and mature tissue. At the molecular level, ligand binding activates Notch signaling by liberating the Notch intracellular domain, which then translocates into the nucleus and activates gene transcription. Despite the elegant simplicity of this pathway, which lacks secondary messengers or a signaling cascade, Notch regulates gene expression in a highly context- and cell-type-dependent manner. Notch signaling is frequently dysregulated, most commonly by overactivation, across many cancers and confers a survival advantage on tumors, leading to poorer outcomes for patients. Recent studies demonstrate how Notch signaling increases tumor cell proliferation and provide evidence that active Notch signaling maintains the cancer stem-cell pool, induces epithelial–mesenchymal transition and promotes chemoresistance. These studies imply that pharmacological inhibition of Notch signaling may refine control of cancer therapy and improve patient survival. Gamma secretase inhibitors (GSIs) are drugs that inhibit Notch signaling and may be successful in controlling cancer cell growth in conjunction with standard chemotherapy, but substantial side effects have hampered their widespread use. Recent efforts have been aimed at the development of antibodies against specific Notch receptors and ligands with the hope of limiting side effects while providing the same therapeutic benefit as GSIs. Together, studies characterizing Notch signaling and modulation have offered hope that refined methods targeting Notch may become powerful tools in anticancer therapeutics. PMID:23585460

  5. The Notch signaling pathway as a mediator of tumor survival.

    PubMed

    Capaccione, Kathleen M; Pine, Sharon R

    2013-07-01

    The Notch signaling pathway is evolutionarily conserved and responsible for cell fate determination in the developing embryo and mature tissue. At the molecular level, ligand binding activates Notch signaling by liberating the Notch intracellular domain, which then translocates into the nucleus and activates gene transcription. Despite the elegant simplicity of this pathway, which lacks secondary messengers or a signaling cascade, Notch regulates gene expression in a highly context- and cell-type-dependent manner. Notch signaling is frequently dysregulated, most commonly by overactivation, across many cancers and confers a survival advantage on tumors, leading to poorer outcomes for patients. Recent studies demonstrate how Notch signaling increases tumor cell proliferation and provide evidence that active Notch signaling maintains the cancer stem-cell pool, induces epithelial-mesenchymal transition and promotes chemoresistance. These studies imply that pharmacological inhibition of Notch signaling may refine control of cancer therapy and improve patient survival. Gamma secretase inhibitors (GSIs) are drugs that inhibit Notch signaling and may be successful in controlling cancer cell growth in conjunction with standard chemotherapy, but substantial side effects have hampered their widespread use. Recent efforts have been aimed at the development of antibodies against specific Notch receptors and ligands with the hope of limiting side effects while providing the same therapeutic benefit as GSIs. Together, studies characterizing Notch signaling and modulation have offered hope that refined methods targeting Notch may become powerful tools in anticancer therapeutics. PMID:23585460

  6. Pharmacology of bile acid receptors: Evolution of bile acids from simple detergents to complex signaling molecules.

    PubMed

    Copple, Bryan L; Li, Tiangang

    2016-02-01

    For many years, bile acids were thought to only function as detergents which solubilize fats and facilitate the uptake of fat-soluble vitamins in the intestine. Many early observations; however, demonstrated that bile acids regulate more complex processes, such as bile acids synthesis and immune cell function through activation of signal transduction pathways. These studies were the first to suggest that receptors may exist for bile acids. Ultimately, seminal studies by many investigators led to the discovery of several bile acid-activated receptors including the farnesoid X receptor, the vitamin D receptor, the pregnane X receptor, TGR5, α5 β1 integrin, and sphingosine-1-phosphate receptor 2. Several of these receptors are expressed outside of the gastrointestinal system, indicating that bile acids may have diverse functions throughout the body. Characterization of the functions of these receptors over the last two decades has identified many important roles for these receptors in regulation of bile acid synthesis, transport, and detoxification; regulation of glucose utilization; regulation of fatty acid synthesis and oxidation; regulation of immune cell function; regulation of energy expenditure; and regulation of neural processes such as gastric motility. Through these many functions, bile acids regulate many aspects of digestion ranging from uptake of essential vitamins to proper utilization of nutrients. Accordingly, within a short time period, bile acids moved beyond simple detergents and into the realm of complex signaling molecules. Because of the important processes that bile acids regulate through activation of receptors, drugs that target these receptors are under development for the treatment of several diseases, including cholestatic liver disease and metabolic syndrome. In this review, we will describe the various bile acid receptors, the signal transduction pathways activated by these receptors, and briefly discuss the physiological processes that

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

    PubMed

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

    2016-03-01

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

  8. A lateral signalling pathway coordinates shape volatility during cell migration

    PubMed Central

    Zhang, Liang; Luga, Valbona; Armitage, Sarah K.; Musiol, Martin; Won, Amy; Yip, Christopher M.; Plotnikov, Sergey V.; Wrana, Jeffrey L.

    2016-01-01

    Cell migration is fundamental for both physiological and pathological processes. Migrating cells usually display high dynamics in morphology, which is orchestrated by an integrative array of signalling pathways. Here we identify a novel pathway, we term lateral signalling, comprised of the planar cell polarity (PCP) protein Pk1 and the RhoGAPs, Arhgap21/23. We show that the Pk1–Arhgap21/23 complex inhibits RhoA, is localized on the non-protrusive lateral membrane cortex and its disruption leads to the disorganization of the actomyosin network and altered focal adhesion dynamics. Pk1-mediated lateral signalling confines protrusive activity and is regulated by Smurf2, an E3 ubiquitin ligase in the PCP pathway. Furthermore, we demonstrate that dynamic interplay between lateral and protrusive signalling generates cyclical fluctuations in cell shape that we quantify here as shape volatility, which strongly correlates with migration speed. These studies uncover a previously unrecognized lateral signalling pathway that coordinates shape volatility during productive cell migration. PMID:27226243

  9. Redefining Signaling Pathways with an Expanding Single-Cell Toolbox.

    PubMed

    Gaudet, Suzanne; Miller-Jensen, Kathryn

    2016-06-01

    Genetically identical cells respond heterogeneously to uniform environmental stimuli. Consequently, investigating the signaling networks that control these cell responses using 'average' bulk cell measurements can obscure underlying mechanisms and misses information emerging from cell-to-cell variability. Here we review recent technological advances including live-cell fluorescence imaging-based approaches and microfluidic devices that enable measurements of signaling networks, dynamics, and responses in single cells. We discuss how these single-cell tools have uncovered novel mechanistic insights for canonical signaling pathways that control cell proliferation (ERK), DNA-damage responses (p53), and innate immune and stress responses (NF-κB). Future improvements in throughput and multiplexing, analytical pipelines, and in vivo applicability will all significantly expand the biological information gained from single-cell measurements of signaling pathways. PMID:26968612

  10. Redefining Signaling Pathways with an Expanding Single-Cell Toolbox.

    PubMed

    Gaudet, Suzanne; Miller-Jensen, Kathryn

    2016-06-01

    Genetically identical cells respond heterogeneously to uniform environmental stimuli. Consequently, investigating the signaling networks that control these cell responses using 'average' bulk cell measurements can obscure underlying mechanisms and misses information emerging from cell-to-cell variability. Here we review recent technological advances including live-cell fluorescence imaging-based approaches and microfluidic devices that enable measurements of signaling networks, dynamics, and responses in single cells. We discuss how these single-cell tools have uncovered novel mechanistic insights for canonical signaling pathways that control cell proliferation (ERK), DNA-damage responses (p53), and innate immune and stress responses (NF-κB). Future improvements in throughput and multiplexing, analytical pipelines, and in vivo applicability will all significantly expand the biological information gained from single-cell measurements of signaling pathways.

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

    PubMed

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

    2016-01-01

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

  12. Pentagone internalises glypicans to fine-tune multiple signalling pathways.

    PubMed

    Norman, Mark; Vuilleumier, Robin; Springhorn, Alexander; Gawlik, Jennifer; Pyrowolakis, George

    2016-01-01

    Tight regulation of signalling activity is crucial for proper tissue patterning and growth. Here we investigate the function of Pentagone (Pent), a secreted protein that acts in a regulatory feedback during establishment and maintenance of BMP/Dpp morphogen signalling during Drosophila wing development. We show that Pent internalises the Dpp co-receptors, the glypicans Dally and Dally-like protein (Dlp), and propose that this internalisation is important in the establishment of a long range Dpp gradient. Pent-induced endocytosis and degradation of glypicans requires dynamin- and Rab5, but not clathrin or active BMP signalling. Thus, Pent modifies the ability of cells to trap and transduce BMP by fine-tuning the levels of the BMP reception system at the plasma membrane. In addition, and in accordance with the role of glypicans in multiple signalling pathways, we establish a requirement of Pent for Wg signalling. Our data propose a novel mechanism by which morphogen signalling is regulated. PMID:27269283

  13. 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.

  14. 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

  15. Transcription Profiles Reveal Sugar and Hormone Signaling Pathways Mediating Flower Induction in Apple (Malus domestica Borkh.).

    PubMed

    Xing, Li-Bo; Zhang, Dong; Li, You-Mei; Shen, Ya-Wen; Zhao, Cai-Ping; Ma, Juan-Juan; An, Na; Han, Ming-Yu

    2015-10-01

    Flower induction in apple (Malus domestica Borkh.) is regulated by complex gene networks that involve multiple signal pathways to ensure flower bud formation in the next year, but the molecular determinants of apple flower induction are still unknown. In this research, transcriptomic profiles from differentiating buds allowed us to identify genes potentially involved in signaling pathways that mediate the regulatory mechanisms of flower induction. A hypothetical model for this regulatory mechanism was obtained by analysis of the available transcriptomic data, suggesting that sugar-, hormone- and flowering-related genes, as well as those involved in cell-cycle induction, participated in the apple flower induction process. Sugar levels and metabolism-related gene expression profiles revealed that sucrose is the initiation signal in flower induction. Complex hormone regulatory networks involved in cytokinin (CK), abscisic acid (ABA) and gibberellic acid pathways also induce apple flower formation. CK plays a key role in the regulation of cell formation and differentiation, and in affecting flowering-related gene expression levels during these processes. Meanwhile, ABA levels and ABA-related gene expression levels gradually increased, as did those of sugar metabolism-related genes, in developing buds, indicating that ABA signals regulate apple flower induction by participating in the sugar-mediated flowering pathway. Furthermore, changes in sugar and starch deposition levels in buds can be affected by ABA content and the expression of the genes involved in the ABA signaling pathway. Thus, multiple pathways, which are mainly mediated by crosstalk between sugar and hormone signals, regulate the molecular network involved in bud growth and flower induction in apple trees. PMID:26412779

  16. Transcription Profiles Reveal Sugar and Hormone Signaling Pathways Mediating Flower Induction in Apple (Malus domestica Borkh.).

    PubMed

    Xing, Li-Bo; Zhang, Dong; Li, You-Mei; Shen, Ya-Wen; Zhao, Cai-Ping; Ma, Juan-Juan; An, Na; Han, Ming-Yu

    2015-10-01

    Flower induction in apple (Malus domestica Borkh.) is regulated by complex gene networks that involve multiple signal pathways to ensure flower bud formation in the next year, but the molecular determinants of apple flower induction are still unknown. In this research, transcriptomic profiles from differentiating buds allowed us to identify genes potentially involved in signaling pathways that mediate the regulatory mechanisms of flower induction. A hypothetical model for this regulatory mechanism was obtained by analysis of the available transcriptomic data, suggesting that sugar-, hormone- and flowering-related genes, as well as those involved in cell-cycle induction, participated in the apple flower induction process. Sugar levels and metabolism-related gene expression profiles revealed that sucrose is the initiation signal in flower induction. Complex hormone regulatory networks involved in cytokinin (CK), abscisic acid (ABA) and gibberellic acid pathways also induce apple flower formation. CK plays a key role in the regulation of cell formation and differentiation, and in affecting flowering-related gene expression levels during these processes. Meanwhile, ABA levels and ABA-related gene expression levels gradually increased, as did those of sugar metabolism-related genes, in developing buds, indicating that ABA signals regulate apple flower induction by participating in the sugar-mediated flowering pathway. Furthermore, changes in sugar and starch deposition levels in buds can be affected by ABA content and the expression of the genes involved in the ABA signaling pathway. Thus, multiple pathways, which are mainly mediated by crosstalk between sugar and hormone signals, regulate the molecular network involved in bud growth and flower induction in apple trees.

  17. The Hippo signaling pathway in liver regeneration and tumorigenesis.

    PubMed

    Hong, Lixin; Cai, Yabo; Jiang, Mingting; Zhou, Dawang; Chen, Lanfen

    2015-01-01

    The Hippo signaling pathway is an evolutionarily conserved signaling module that plays critical roles in liver size control and tumorigenesis. The Hippo pathway consists of a core kinase cascade in which the mammalian Ste20-like kinases (Mst1/2, orthologs of Drosophila Hippo) and their cofactor Salvador (Sav1) form a complex to phosphorylate and activate the large tumor suppressor (Lats1/2). Lats1/2 kinases in turn phosphorylate and inhibit the transcription co-activators, the Yes-associated protein (YAP) and the transcriptional co-activator with PDZ-binding motif (TAZ), two major downstream effectors of the Hippo pathway. Losses of the Hippo pathway components induce aberrant hepatomegaly and tumorigenesis, in which YAP coordinates regulation of cell proliferation and apoptosis and plays an essential role. This review summarizes the current findings of the regulation of Hippo signaling in liver regeneration and tumorigenesis, focusing on how the loss of tumor suppressor components of the Hippo pathway results in liver cancers and discussing the molecular mechanisms that regulate the expression and activation of its downstream effector YAP in liver tumorigenesis.

  18. Integrating Retinoic Acid Signaling with Brain Function

    ERIC Educational Resources Information Center

    Luo, Tuanlian; Wagner, Elisabeth; Drager, Ursula C.

    2009-01-01

    The vitamin A derivative retinoic acid (RA) regulates the transcription of about a 6th of the human genome. Compelling evidence indicates a role of RA in cognitive activities, but its integration with the molecular mechanisms of higher brain functions is not known. Here we describe the properties of RA signaling in the mouse, which point to…

  19. Targeting stem cell signaling pathways for drug discovery: advances in the Notch and Wnt pathways.

    PubMed

    An, Songzhu Michael; Ding, Qiang; Zhang, Jie; Xie, JingYi; Li, LingSong

    2014-06-01

    Signaling pathways transduce extracellular stimuli into cells through molecular cascades to regulate cellular functions. In stem cells, a small number of pathways, notably those of TGF-β/BMP, Hedgehog, Notch, and Wnt, are responsible for the regulation of pluripotency and differentiation. During embryonic development, these pathways govern cell fate specifications as well as the formation of tissues and organs. In adulthood, their normal functions are important for tissue homeostasis and regeneration, whereas aberrations result in diseases, such as cancer and degenerative disorders. In complex biological systems, stem cell signaling pathways work in concert as a network and exhibit crosstalk, such as the negative crosstalk between Wnt and Notch. Over the past decade, genetic and genomic studies have identified a number of potential drug targets that are involved in stem cell signaling pathways. Indeed, discovery of new targets and drugs for these pathways has become one of the most active areas in both the research community and pharmaceutical industry. Remarkable progress has been made and several promising drug candidates have entered into clinical trials. This review focuses on recent advances in the discovery of novel drugs which target the Notch and Wnt pathways.

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

    PubMed Central

    Erion, Renske; Sehgal, Amita

    2013-01-01

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

  1. Cellular metabolic and autophagic pathways: traffic control by redox signaling.

    PubMed

    Dodson, Matthew; Darley-Usmar, Victor; Zhang, Jianhua

    2013-10-01

    It has been established that the key metabolic pathways of glycolysis and oxidative phosphorylation are intimately related to redox biology through control of cell signaling. Under physiological conditions glucose metabolism is linked to control of the NADH/NAD redox couple, as well as providing the major reductant, NADPH, for thiol-dependent antioxidant defenses. Retrograde signaling from the mitochondrion to the nucleus or cytosol controls cell growth and differentiation. Under pathological conditions mitochondria are targets for reactive oxygen and nitrogen species and are critical in controlling apoptotic cell death. At the interface of these metabolic pathways, the autophagy-lysosomal pathway functions to maintain mitochondrial quality and generally serves an important cytoprotective function. In this review we will discuss the autophagic response to reactive oxygen and nitrogen species that are generated from perturbations of cellular glucose metabolism and bioenergetic function.

  2. Organic acid component from Taraxacum mongolicum Hand.-Mazz alleviates inflammatory injury in lipopolysaccharide-induced acute tracheobronchitis of ICR mice through TLR4/NF-κB signaling pathway.

    PubMed

    Yang, Nan; Li, Chao; Tian, Gang; Zhu, Maomao; Bu, Weiquan; Chen, Juan; Hou, Xuefeng; Di, Liuqing; Jia, Xiaobin; Dong, Zibo; Feng, Liang

    2016-05-01

    Inflammation plays an important role in the pathogenesis of acute tracheobronchitis. Taraxacum mongolicum Hand.-Mazz (TMHM) is a dietic herb for heat-clearing and detoxifying functions as well as swell-reducing and mass-resolving effect in Traditional Chinese Medicine. Studies have shown that its major ingredient organic acid component (OAC) possesses favorable anti-inflammatory activity. However, the protective effect of OAC from TMHM (TMHM-OAC) on inflammatory injury of acute tracheobronchitis and its possible mechanism remains poorly understood. In this study, HPLC-DAD was used to analyze the components of TMHM-OAC. Lipopolysaccharide of 1mg/ml was used to induce respiratory inflammation in ICR mice at the dose of 5mg/kg by intratracheally aerosol administration. Enzyme-linked immunosorbent assay (ELISA) was employed to detect the levels of inflammation factors such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and nitric oxide in serum and supernatant of trachea tissue. Western blotting (WB) and Immunohistochemistry analysis (IHC) were conducted in parallel to determine TNF-α, IL-6, inducible nitric oxide synthase (iNOS), Toll-like receptors 4(TLR4) protein expressions and nuclear factor-kappa B p65 (NF-κB p65) phosphorylation. Hematoxylin-Eosin staining (HE) was applied to evaluate pathological lesions of trachea tissue. Experimental results showed that TMHM-OAC significantly reduced the levels of the TNF-α, IL-6 and NO in serum and supernatant of tracheal of LPS-induced ICR mice. The protein expression levels of TNF-α, IL-6 and iNOS in tracheal tissue were also down-regulated significantly by the treatment of TMHM-OAC. Moreover, TMHM-OAC downregulated phosphorylation of NF-κB p65 and protein expression of TLR4. Our results indicated that TMHM-OAC could improve LPS-induced histopathological damage of tracheal tissues through the regulation of TLR4/NF-κB signaling pathway and could be beneficial for the treatment of acute tracheobronchitis

  3. Organic acid component from Taraxacum mongolicum Hand.-Mazz alleviates inflammatory injury in lipopolysaccharide-induced acute tracheobronchitis of ICR mice through TLR4/NF-κB signaling pathway.

    PubMed

    Yang, Nan; Li, Chao; Tian, Gang; Zhu, Maomao; Bu, Weiquan; Chen, Juan; Hou, Xuefeng; Di, Liuqing; Jia, Xiaobin; Dong, Zibo; Feng, Liang

    2016-05-01

    Inflammation plays an important role in the pathogenesis of acute tracheobronchitis. Taraxacum mongolicum Hand.-Mazz (TMHM) is a dietic herb for heat-clearing and detoxifying functions as well as swell-reducing and mass-resolving effect in Traditional Chinese Medicine. Studies have shown that its major ingredient organic acid component (OAC) possesses favorable anti-inflammatory activity. However, the protective effect of OAC from TMHM (TMHM-OAC) on inflammatory injury of acute tracheobronchitis and its possible mechanism remains poorly understood. In this study, HPLC-DAD was used to analyze the components of TMHM-OAC. Lipopolysaccharide of 1mg/ml was used to induce respiratory inflammation in ICR mice at the dose of 5mg/kg by intratracheally aerosol administration. Enzyme-linked immunosorbent assay (ELISA) was employed to detect the levels of inflammation factors such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and nitric oxide in serum and supernatant of trachea tissue. Western blotting (WB) and Immunohistochemistry analysis (IHC) were conducted in parallel to determine TNF-α, IL-6, inducible nitric oxide synthase (iNOS), Toll-like receptors 4(TLR4) protein expressions and nuclear factor-kappa B p65 (NF-κB p65) phosphorylation. Hematoxylin-Eosin staining (HE) was applied to evaluate pathological lesions of trachea tissue. Experimental results showed that TMHM-OAC significantly reduced the levels of the TNF-α, IL-6 and NO in serum and supernatant of tracheal of LPS-induced ICR mice. The protein expression levels of TNF-α, IL-6 and iNOS in tracheal tissue were also down-regulated significantly by the treatment of TMHM-OAC. Moreover, TMHM-OAC downregulated phosphorylation of NF-κB p65 and protein expression of TLR4. Our results indicated that TMHM-OAC could improve LPS-induced histopathological damage of tracheal tissues through the regulation of TLR4/NF-κB signaling pathway and could be beneficial for the treatment of acute tracheobronchitis.

  4. New Insights into Reelin-Mediated Signaling Pathways

    PubMed Central

    Lee, Gum Hwa; D’Arcangelo, Gabriella

    2016-01-01

    Reelin, a multifunctional extracellular protein that is important for mammalian brain development and function, is secreted by different cell types in the prenatal or postnatal brain. The spatiotemporal regulation of Reelin expression and distribution during development relates to its multifaceted function in the brain. Prenatally Reelin controls neuronal radial migration and proper positioning in cortical layers, whereas postnatally Reelin promotes neuronal maturation, synaptic formation and plasticity. The molecular mechanisms underlying the distinct biological functions of Reelin during and after brain development involve unique and overlapping signaling pathways that are activated following Reelin binding to its cell surface receptors. Distinct Reelin ligand isoforms, such as the full-length protein or fragments generated by proteolytic cleavage differentially affect the activity of downstream signaling pathways. In this review, we discuss recent advances in our understanding of the signaling transduction pathways activated by Reelin that regulate different aspects of brain development and function. A core signaling machinery, including ApoER2/VLDLR receptors, Src/Fyn kinases, and the adaptor protein Dab1, participates in all known aspects of Reelin biology. However, distinct downstream mechanisms, such as the Crk/Rap1 pathway and cell adhesion molecules, play crucial roles in the control of neuronal migration, whereas the PI3K/Akt/mTOR pathway appears to be more important for dendrite and spine development. Finally, the NMDA receptor (NMDAR) and an unidentified receptor contribute to the activation of the MEK/Erk1/2 pathway leading to the upregulation of genes involved in synaptic plasticity and learning. This knowledge may provide new insight into neurodevelopmental or neurodegenerative disorders that are associated with Reelin dysfunction. PMID:27242434

  5. Current perspectives of the signaling pathways directing neural crest induction.

    PubMed

    Stuhlmiller, Timothy J; García-Castro, Martín I

    2012-11-01

    The neural crest is a migratory population of embryonic cells with a tremendous potential to differentiate and contribute to nearly every organ system in the adult body. Over the past two decades, an incredible amount of research has given us a reasonable understanding of how these cells are generated. Neural crest induction involves the combinatorial input of multiple signaling pathways and transcription factors, and is thought to occur in two phases from gastrulation to neurulation. In the first phase, FGF and Wnt signaling induce NC progenitors at the border of the neural plate, activating the expression of members of the Msx, Pax, and Zic families, among others. In the second phase, BMP, Wnt, and Notch signaling maintain these progenitors and bring about the expression of definitive NC markers including Snail2, FoxD3, and Sox9/10. In recent years, additional signaling molecules and modulators of these pathways have been uncovered, creating an increasingly complex regulatory network. In this work, we provide a comprehensive review of the major signaling pathways that participate in neural crest induction, with a focus on recent developments and current perspectives. We provide a simplified model of early neural crest development and stress similarities and differences between four major model organisms: Xenopus, chick, zebrafish, and mouse. PMID:22547091

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

    PubMed

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

    2006-02-01

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

  7. Current perspectives of the signaling pathways directing neural crest induction.

    PubMed

    Stuhlmiller, Timothy J; García-Castro, Martín I

    2012-11-01

    The neural crest is a migratory population of embryonic cells with a tremendous potential to differentiate and contribute to nearly every organ system in the adult body. Over the past two decades, an incredible amount of research has given us a reasonable understanding of how these cells are generated. Neural crest induction involves the combinatorial input of multiple signaling pathways and transcription factors, and is thought to occur in two phases from gastrulation to neurulation. In the first phase, FGF and Wnt signaling induce NC progenitors at the border of the neural plate, activating the expression of members of the Msx, Pax, and Zic families, among others. In the second phase, BMP, Wnt, and Notch signaling maintain these progenitors and bring about the expression of definitive NC markers including Snail2, FoxD3, and Sox9/10. In recent years, additional signaling molecules and modulators of these pathways have been uncovered, creating an increasingly complex regulatory network. In this work, we provide a comprehensive review of the major signaling pathways that participate in neural crest induction, with a focus on recent developments and current perspectives. We provide a simplified model of early neural crest development and stress similarities and differences between four major model organisms: Xenopus, chick, zebrafish, and mouse.

  8. Pentoxifylline inhibits liver fibrosis via hedgehog signaling pathway.

    PubMed

    Li, Hui; Hua, Juan; Guo, Chun-Xia; Wang, Wei-Xian; Wang, Bao-Ju; Yang, Dong-Liang; Wei, Ping; Lu, Yin-Ping

    2016-06-01

    Infection of schistosomiasis japonica may eventually lead to liver fibrosis, and no effective antifibrotic therapies are available but liver transplantation. Hedgehog (HH) signaling pathway has been involved in the process and is a promising target for treating liver fibrosis. This study aimed to explore the effects of pentoxifylline (PTX) on liver fibrosis induced by schistosoma japonicum infection by inhibiting the HH signaling pathway. Phorbol12-myristate13-acetate (PMA) was used to induce human acute mononuclear leukemia cells THP-1 to differentiate into macrophages. The THP-1-derived macrophages were stimulated by soluble egg antigen (SEA), and the culture supernatants were collected for detection of activation of macrophages. Cell Counting Kit-8 (CCK-8) was used to detect the cytotoxicity of the culture supernatant and PTX on the LX-2 cells. The LX-2 cells were administered with activated culture supernatant from macrophages and(or) PTX to detect the transforming growth factor-β gene expression. The mRNA expression of shh and gli-1, key parts in HH signaling pathway, was detected. The mRNA expression of shh and gli-1 was increased in LX-2 cells treated with activated macrophages-derived culture supernatant, suggesting HH signaling pathway may play a key role in the activation process of hepatic stellate cells (HSCs). The expression of these genes decreased in LX-2 cells co-cultured with both activated macrophages-derived culture supernatant and PTX, indicating PTX could suppress the activation process of HSCs. In conclusion, these data provide evidence that PTX prevents liver fibrogenesis in vitro by the suppression of HH signaling pathway. PMID:27376806

  9. Signaling Pathways That Control mRNA Turnover

    PubMed Central

    Thapar, Roopa; Denmon, Andria P.

    2013-01-01

    Cells regulate their genomes mainly at the level of transcription and at the level of mRNA decay. While regulation at the level of transcription is clearly important, the regulation of mRNA turnover by signaling networks is essential for a rapid response to external stimuli. Signaling pathways result in posttranslational modification of RNA binding proteins by phosphorylation, ubiquitination, methylation, acetylation etc. These modifications are important for rapid remodeling of dynamic ribonucleoprotein complexes and triggering mRNA decay. Understanding how these posttranslational modifications alter gene expression is therefore a fundamental question in biology. In this review we highlight recent findings on how signaling pathways and cell cycle checkpoints involving phosphorylation, ubiquitination, and arginine methylation affect mRNA turnover. PMID:23602935

  10. Stress Signaling Pathways for the Pathogenicity of Cryptococcus

    PubMed Central

    Jung, Kwang-Woo

    2013-01-01

    Sensing, responding, and adapting to the surrounding environment are crucial for all living organisms to survive, proliferate, and differentiate in their biological niches. This ability is also essential for Cryptococcus neoformans and its sibling species Cryptococcus gattii, as these pathogens have saprobic and parasitic life cycles in natural and animal host environments. The ability of Cryptococcus to cause fatal meningoencephalitis is highly related to its capability to remodel and optimize its metabolic and physiological status according to external cues. These cues act through multiple stress signaling pathways through a panoply of signaling components, including receptors/sensors, small GTPases, secondary messengers, kinases, transcription factors, and other miscellaneous adaptors or regulators. In this minireview, we summarize and highlight the importance of several stress signaling pathways that influence the pathogenicity of Cryptococcus and discuss future challenges in these areas. PMID:24078305

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

    PubMed Central

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

    2016-01-01

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

  12. Asymptotic Analysis of the Wnt/β Signaling Pathway

    NASA Astrophysics Data System (ADS)

    Maris, D. T.; Goussis, D. A.

    2015-01-01

    The Wnt/β-catenin pathway is a signal transduction pathway made of proteins, which plays an important role in oncogenesis. Ethan Lee and and co-workers introduced in 2003 a detailed mathematical model of this pathway, incorporating the kinetics of protein-protein interactions, protein synthesis/degradation and phosphorylation/dephosphorylation. The fast/slow dynamics of Lee's system are examined here, by employing the Computational Singular Perturbation (CSP) algorithm. CSP reproduces the results of the classical singular perturbation analysis in an algorithmic fashion, producing an approximation of (i) the low dimensional Slow Invariant Manifold (SIM), where the solution evolves and (ii) the reduced model that governs the flow there. The temporal variation of the dimensions of the SIM will be presented and the components of the pathway that are responsible (i) for the generation of the SIM and (ii) for driving the system on it will be identified.

  13. Alternative fermentation pathway of cinnamic acid production via phenyllactic acid.

    PubMed

    Masuo, Shunsuke; Kobayashi, Yuta; Oinuma, Ken-Ichi; Takaya, Naoki

    2016-10-01

    Cinnamic acid (CA) is the chemical basis for bulk production of flavoring reagents and chemical intermediates, and it can be fermented from biomass. Phenylalanine ammonia lyase (PAL) has been used exclusively in the bacterial fermentation of sugar biomass in which the fermentation intermediate phenylalanine is deaminated to CA. Here, we designed an alternative metabolic pathway for fermenting glucose to CA. An Escherichia coli strain that generates phenylalanine in this pathway also produces Wickerhamia fluorescens phenylpyruvate reductase and ferments glucose to D-phenyllactate (D-PhLA) (Fujita et al. Appl Microbiol Biotechnol 97: 8887-8894, 2013). Thereafter, phenyllactate dehydratase encoded by fldABCI genes in Clostridium sporogenes converts the resulting D-PhLA into CA. The phenyllactate dehydratase expressed by fldABCI in the D-PhLA-producing bacterium fermented glucose to CA, but D-PhLA fermentation and phenyllactate dehydration were aerobic and anaerobic processes, respectively, which disrupted high-yield CA fermentation in single batch cultures. We overcame this disruption by sequentially culturing the two strains under aerobic and anaerobic conditions. We optimized the incubation periods of the respective aeration steps to produce 1.7 g/L CA from glucose, which exceeded the yield from PAL-dependent glucose fermentation to CA 11-fold. This process is a novel, efficient alternative to conventional PAL-dependent CA production.

  14. Lysophosphatidic Acid (LPA) Signaling in Vertebrate Reproduction

    PubMed Central

    Ye, Xiaoqin; Chun, Jerold

    2009-01-01

    Lysophosphatidic acid (LPA) is a cell membrane phospholipid metabolite that can act as an extracellular signal. Its effects are mediated through at least five G protein-coupled receptors (GPCRs), LPA1-5, and likely others as well. Studies in multiple species including LPA receptor-deficient mice and humans have identified or implicated important roles for receptor-mediated LPA signaling in multiple aspects of vertebrate reproduction. These include ovarian function, spermatogenesis, fertilization, early embryo development, embryo implantation, embryo spacing, decidualization, pregnancy maintenance, and parturition. LPA signaling may also have pathological consequences, influencing aspects of endometriosis and ovarian cancer. Here we review recent progress in LPA signaling research relevant to female and male reproduction. PMID:19836970

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

    PubMed

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

    2015-07-01

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

  16. Role of the ceramide-signaling pathways in ionizing radiation-induced apoptosis.

    PubMed

    Vit, Jean-Philippe; Rosselli, Filippo

    2003-11-27

    Ionizing radiations (IR) exposure leads to damage on several cellular targets. How signals from different targets are integrated to determine the cell fate remains a controversial issue. Understanding the pathway(s) responsible(s) for the cell killing effect of the IR exposure is of prime importance in light of using radiations as anticancer agent or as diagnostic tool. In this study, we have established that IR-induced cell damage initiates two independent signaling pathways that lead to a biphasic intracellular ceramide increase. A transitory increase of ceramide is observed within minutes after IR exposure as a consequence of DNA damage-independent acid sphingomyelinase activation. Several hours after irradiation, a second wave of ceramide accumulation is observed depending on the DNA damage-dependent activation of ceramide synthase, which requires a signaling pathway involving ATM. Importantly, we have demonstrated that the late ceramide accumulation is also dependent on the first one and is rate limiting for the apoptotic process induced by IR. In conclusion, our observations suggest that ceramide is a major determinant of the IR-induced apoptotic process at the cross-point of different signal transduction pathways.

  17. Regulation of various proteolytic pathways by insulin and amino acids in human fibroblasts.

    PubMed

    Esteban, Inmaculada; Aguado, Carmen; Sánchez, Maribel; Knecht, Erwin

    2007-07-24

    Intracellular protein degradation is a regulated process with several proteolytic pathways. Although regulation of macroautophagy has been investigated in some detail in hepatocytes and in few other cells, less is known on this regulation in other cells and proteolytic pathways. We show that in human fibroblasts insulin and amino acids reduce protein degradation by different signalling pathways and that this inhibition proceeds in part via the mammalian target of rapamycin, especially with amino acids, which probably increase lysosomal pH. Moreover, the regulatory amino acids (Phe, Arg, Met, Tyr, Trp and Cys) are partially different from other cells. Finally, and in addition to macroautophagy, insulin and amino acids modify, to different extents and sometimes in opposite directions, the activities of other proteolytic pathways.

  18. Quantitative structure-property relationship studies on amino acid conjugates of jasmonic acid as defense signaling molecules.

    PubMed

    Li, Zu-Guang; Chen, Ke-Xian; Xie, Hai-Ying; Gao, Jian-Rong

    2009-06-01

    Jasmonates and related compounds, including amino acid conjugates of jasmonic acid, have regulatory functions in the signaling pathway for plant developmental processes and responses to the complex equilibrium of biotic and abiotic stress. But the molecular details of the signaling mechanism are still poorly understood. Statistically significant quantitative structure-property relationship models (r(2) > 0.990) constructed by genetic function approximation and molecular field analysis were generated for the purpose of deriving structural requirements for lipophilicity of amino acid conjugates of jasmonic acid. The best models derived in the present study provide some valuable academic information in terms of the 2/3D-descriptors influencing the lipophilicity, which may contribute to further understanding the mechanism of exogenous application of jasmonates in their signaling pathway and designing novel analogs of jasmonic acid as ecological pesticides.

  19. Retinoic acid-induced expression of apolipoprotein D and concomitant growth arrest in human breast cancer cells are mediated through a retinoic acid receptor RARalpha-dependent signaling pathway.

    PubMed

    López-Boado, Y S; Klaus, M; Dawson, M I; López-Otín, C

    1996-12-13

    Apolipoprotein D (apoD) is a human plasma protein, belonging to the lipocalin superfamily, that is produced by a specific subtype of highly differentiated breast carcinomas and that is strongly up-regulated by retinoic acid (RA) in breast cancer cells. In this work, we have examined the molecular mechanisms mediating the induction of apoD gene expression by retinoids in T-47D human breast cancer cells. Northern blot analysis revealed that Ro40-6055, a synthetic retinoid that selectively binds and activates the retinoic acid receptor RARalpha, induced the accumulation of apoD mRNA in breast cancer cells in a time- and dose-dependent manner. The time course analysis demonstrated that apoD mRNA was induced 14-fold over control cells after 48 h of incubation with 10(-8) M Ro40-6055. As little as 10(-11) M of this retinoid induced apoD mRNA 5-fold over the control, whereas incubation with 10(-7) M Ro40-6055 induced maximally 15-fold over control cells. RARalpha-selective antagonists counteracted the inductive effects of all-trans-RA, 9-cis-RA, and Ro40-6055 on the expression of apoD, when present at the same concentration as the retinoid agonists. By contrast, RARbeta-, RARgamma-, and RXR-selective retinoids did not affect apoD gene expression. The retinoid agonist Ro40-6055 had an antiproliferative effect on T-47D cells, with maximal growth inhibition of approximately 60% obtained after 7 days of incubation with 10(-7) M. This antiproliferative effect could be counteracted by a 100-fold excess of the antagonist Ro41-5253. Treatment of the cells with retinoids that do not bind the nuclear retinoic acid receptors did not affect apoD expression, despite the fact that they did have a strong antiproliferative effect on T-47D cells. On the basis of these results, a role for RARalpha on apoD gene expression induction by retinoids in breast cancer cells is proposed.

  20. Distinct amino acid-sensing mTOR pathways regulate skeletal myogenesis.

    PubMed

    Yoon, Mee-Sup; Chen, Jie

    2013-12-01

    Signaling through the mammalian target of rapamycin (mTOR) in response to amino acid availability controls many cellular and developmental processes. mTOR is a master regulator of myogenic differentiation, but the pathways mediating amino acid signals in this process are not known. Here we examine the Rag GTPases and the class III phosphoinositide 3-kinase (PI3K) Vps34, two mediators of amino acid signals upstream of mTOR complex 1 (mTORC1) in cell growth regulation, for their potential involvement in myogenesis. We find that, although both Rag and Vps34 mediate amino acid activation of mTORC1 in C2C12 myoblasts, they have opposing functions in myogenic differentiation. Knockdown of RagA/B enhances, whereas overexpression of active RagB/C mutants impairs, differentiation, and this inhibitory function of Rag is mediated by mTORC1 suppression of the IRS1-PI3K-Akt pathway. On the other hand, Vps34 is required for myogenic differentiation. Amino acids activate a Vps34-phospholipase D1 (PLD1) pathway that controls the production of insulin-like growth factor II, an autocrine inducer of differentiation, through the Igf2 muscle enhancer. The product of PLD, phosphatidic acid, activates the enhancer in a rapamycin-sensitive but mTOR kinase-independent manner. Our results uncover amino acid-sensing mechanisms controlling the homeostasis of myogenesis and underline the versatility and context dependence of mTOR signaling.

  1. The Ectodysplasin and NFkappaB signalling pathways in odontogenesis.

    PubMed

    Courtney, Jo-Maree; Blackburn, James; Sharpe, Paul T

    2005-02-01

    Hypohidrotic ectodermal dysplasia (HED) is a congenital disorder affecting organs of ectodermal origin including teeth, hair and sweat glands. Defects in Ectodysplasin (tabby), Edar (downless) and Edar associated death domain (Edaradd) (crinkled) cause HED in both humans and mice. Ectodysplasin is a tumour necrosis factor (TNF) superfamily member whose downstream signalling is transduced by the inhibitor of kappaB kinase (IKK) complex and inhibitors of kappaB (IkappaB) to activate the transcription factor NFkappaB. NFkappaB signalling is involved in a wide range of cellular processes and at each stage the different family members must be tightly regulated for each function. Recent data have demonstrated the importance of this signalling pathway in odontogenesis, particularly in the formation of cusps. Here we review recent advances in our understanding of Ectodysplasin/NFkappaB signalling in tooth development and in particular the central role of the IKK complex.

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

    PubMed

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

    2016-08-23

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

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

    PubMed Central

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

    2016-01-01

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

  4. Molecular Genetic Characterization of Terreic Acid Pathway in Aspergillus terreus

    DOE PAGESBeta

    Guo, Chun-Jun; Sun, Wei-wen; Bruno, Kenneth S.; Wang, Clay C.

    2014-09-29

    Terreic acid is a natural product derived from 6-methylsalicylic acid (6-MSA). A compact gene cluster for its biosynthesis was characterized. Isolation of the intermediates and shunt products from the mutant strains, in combined with bioinformatic analyses, allowed us to propose a biosynthetic pathway for terreic acid. Lastly, defining the pathway and the genes involved will facilitate the engineering of this molecule with interesting antimicrobial and antitumor bioactivities.

  5. Expression pattern of the Hedgehog signaling pathway in pituitary adenomas.

    PubMed

    Yavropoulou, Maria P; Maladaki, Anna; Topouridou, Konstantina; Kotoula, Vasiliki; Poulios, Chris; Daskalaki, Emily; Foroglou, Nikolaos; Karkavelas, George; Yovos, John G

    2016-01-12

    Several studies have demonstrated the role of Wnt and Notch signaling in the pathogenesis of pituitary adenomas, but data are scarce regarding the role of Hedgehog signaling. In this study we investigated the differential expression of gene targets of the Hedgehog signaling pathway. Formalin-fixed, paraffin-embedded specimens from adult patients who underwent transphenoidal resection and normal human pituitary tissues that were obtained from autopsies were used. Clinical information and data from pre-operative MRI scan (extracellular tumor extension, tumor size, displacement of the optic chiasm) were retrieved from the Hospital's database. We used a customized RT(2) Profiler PCR Array, to investigate the expression of genes related to Notch and Hedgehog signaling pathways (PTCH1, PTCH2, GLI1, GLI3, NOTCH3, JAG1, HES1, and HIP). A total of 52 pituitary adenomas (32 non-functioning adenomas, 15 somatotropinomas and 5 prolactinomas) were used in the final analysis. In non-functioning pituitary adenomas there was a significant decrease (approximately 75%) in expression of all Hedgehog related genes that were tested, while Notch3 and Jagged-1 expression was found significantly increased, compared with normal pituitary tissue controls. In contrast, somatotropinomas demonstrated a significant increase in expression of all Hedgehog related genes and a decrease in the expression of Notch3 and Jagged-1. There was no significant difference in the expression of Hedgehog and Notch related genes between prolactinomas and healthy pituitary tissues. Hedgehog signalling appears to be activated in somatotropinomas but not in non-functioning pituitary adenomas in contrast to the expression pattern of Notch signalling pathway. PMID:26620835

  6. Arbuscular Mycorrhiza–Specific Signaling in Rice Transcends the Common Symbiosis Signaling Pathway[W

    PubMed Central

    Gutjahr, Caroline; Banba, Mari; Croset, Vincent; An, Kyungsook; Miyao, Akio; An, Gynheung; Hirochika, Hirohiko; Imaizumi-Anraku, Haruko; Paszkowski, Uta

    2008-01-01

    Knowledge about signaling in arbuscular mycorrhizal (AM) symbioses is currently restricted to the common symbiosis (SYM) signaling pathway discovered in legumes. This pathway includes calcium as a second messenger and regulates both AM and rhizobial symbioses. Both monocotyledons and dicotyledons form symbiotic associations with AM fungi, and although they differ markedly in the organization of their root systems, the morphology of colonization is similar. To identify and dissect AM-specific signaling in rice (Oryza sativa), we developed molecular phenotyping tools based on gene expression patterns that monitor various steps of AM colonization. These tools were used to distinguish common SYM-dependent and -independent signaling by examining rice mutants of selected putative legume signaling orthologs predicted to be perturbed both upstream (CASTOR and POLLUX) and downstream (CCAMK and CYCLOPS) of the central, calcium-spiking signal. All four mutants displayed impaired AM interactions and altered AM-specific gene expression patterns, therefore demonstrating functional conservation of SYM signaling between distant plant species. In addition, differential gene expression patterns in the mutants provided evidence for AM-specific but SYM-independent signaling in rice and furthermore for unexpected deviations from the SYM pathway downstream of calcium spiking. PMID:19033527

  7. Preface: cardiac control pathways: signaling and transport phenomena.

    PubMed

    Sideman, Samuel

    2008-03-01

    Signaling is part of a complex system of communication that governs basic cellular functions and coordinates cellular activity. Transfer of ions and signaling molecules and their interactions with appropriate receptors, transmembrane transport, and the consequent intracellular interactions and functional cellular response represent a complex system of interwoven phenomena of transport, signaling, conformational changes, chemical activation, and/or genetic expression. The well-being of the cell thus depends on a harmonic orchestration of all these events and the existence of control mechanisms that assure the normal behavior of the various parameters involved and their orderly expression. The ability of cells to sustain life by perceiving and responding correctly to their microenvironment is the basis for development, tissue repair, and immunity, as well as normal tissue homeostasis. Natural deviations, or human-induced interference in the signaling pathways and/or inter- and intracellular transport and information transfer, are responsible for the generation, modulation, and control of diseases. The present overview aims to highlight some major topics of the highly complex cellular information transfer processes and their control mechanisms. Our goal is to contribute to the understanding of the normal and pathophysiological phenomena associated with cardiac functions so that more efficient therapeutic modalities can be developed. Our objective in this volume is to identify and enhance the study of some basic passive and active physical and chemical transport phenomena, physiological signaling pathways, and their biological consequences.

  8. Signal transduction pathways involved in mechanotransduction in bone cells

    SciTech Connect

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

    2006-10-13

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

  9. SNIP1: a new activator of HSE signaling pathway.

    PubMed

    Li, Qiang; An, Jian; Liu, Xianghua; Zhang, Mingjun; Ling, Yichen; Wang, Chenji; Zhao, Jing; Yu, Long

    2012-03-01

    In the last 10 years, more and more attention has been focused on SNIP1 (Smad nuclear interacting protein 1), which functions as a transcriptional coactivator. We report here that through quantitative real-time PCR analysis in 18 different human tissues, SNIP1 was found to be expressed ubiquitously. When overexpressed in HeLa cells, SNIP1-EGFP fused protein exhibited a nuclear localization with a characteristic subnuclear distribution in speckles or formed larger discrete nuclear bodies in some cells. Reporter gene assay showed that overexpression of SNIP1 in HEK 293 cells or H1299 cells strongly activated the HSE signaling pathway. Moreover, SNIP1 could selectively regulate the transcription of HSP70A1A and HSP27. Taken together, our findings suggest that SNIP1 might also be a positive regulator of HSE signaling pathway.

  10. Development of Inhibitors of Salicylic Acid Signaling.

    PubMed

    Jiang, Kai; Kurimoto, Tetsuya; Seo, Eun-kyung; Miyazaki, Sho; Nakajima, Masatoshi; Nakamura, Hidemitsu; Asami, Tadao

    2015-08-19

    Salicylic acid (SA) plays important roles in the induction of systemic acquired resistance (SAR) in plants. Determining the mechanism of SAR will extend our understanding of plant defenses against pathogens. We recently reported that PAMD is an inhibitor of SA signaling, which suppresses the expression of the pathogenesis-related PR genes and is expected to facilitate the understanding of SA signaling. However, PAMD strongly inhibits plant growth. To minimize the side effects of PAMD, we synthesized a number of PAMD derivatives, and identified compound 4 that strongly suppresses the expression of the PR genes with fewer adverse effects on plant growth than PAMD. We further showed that the adverse effects on plant growth were partially caused the stabilization of DELLA, which is also related to the pathogen responses. These results indicate that compound 4 would facilitate our understanding of SA signaling and its cross talk with other plant hormones.

  11. Estrogen Stimulation of Cell Migration Involves Multiple Signaling Pathway Interactions

    PubMed Central

    Li, Yan; Wang, Ji-Ping; Santen, Richard J.; Kim, Tae-Hyun; Park, Hoyong; Fan, Ping; Yue, Wei

    2010-01-01

    Hormone-dependent breast cancers respond to inhibitors of estrogen synthesis or action with tumor regression and with a reduction of new metastases. The mechanisms underlying the effects of estrogen on metastasis likely differ from those on tumor regression. Cell migration is a key first step in the metastatic process. Based on our prior work and other published data, we designed and tested a working model that suggested that estrogen receptor α, epidermal growth factor receptor, focal adhesion kinase (FAK), paxillin, phosphatidylinositol 3 kinase, p60 Src tyrosine kinase (c-Src), c-Jun N-terminal kinase, and MAPK interact to facilitate estradiol (E2)-induced cell migration. Accordingly, we examined the effect of E2 on activation of these pathways and demonstrated mechanistic effects by blocking each component and assessing cell migration as a biologic endpoint. Initial studies validated a robust cell migration assay characterized by highly reproducible, dose-dependent responses to E2. Examining various mechanisms involved in migration, we showed that E2 induced activation of c-Src, FAK, and paxillin with early peaks within 5–30 min and later peaks at 24 h. ERK and protein kinase B phosphorylation exhibited only early peaks. Blockade of various steps in these signaling pathways with use of small interfering RNA or specific inhibitors demonstrated mechanistic effects of these signaling molecules on cell migration. Our results suggest that the effects of E2 on cell migration involve multiple, interacting signaling pathways. Important effects are mediated by the MAPK, phosphatidylinositol 3 kinase, and c-Jun N-terminal kinase pathways and use FAK, paxillin, and c-Src for activation. Each pathway represents a potential target for blocking cell migration and metastasis of breast cancer cells. PMID:20861240

  12. Gene expression analysis of aberrant signaling pathways in meningiomas

    PubMed Central

    TORRES-MARTÍN, MIGUEL; MARTINEZ-GLEZ, VICTOR; PEÑA-GRANERO, CAROLINA; ISLA, ALBERTO; LASSALETTA, LUIS; DE CAMPOS, JOSE M.; PINTO, GIOVANNY R.; BURBANO, ROMMEL R.; MELÉNDEZ, BÁRBARA; CASTRESANA, JAVIER S.; REY, JUAN A.

    2013-01-01

    Examining aberrant pathway alterations is one method for understanding the abnormal signals that are involved in tumorigenesis and tumor progression. In the present study, expression arrays were performed on tumor-related genes in meningiomas. The GE Array Q Series HS-006 was used to determine the expression levels of 96 genes that corresponded to six primary biological regulatory pathways in a series of 42 meningiomas, including 32 grade I, four recurrent grade I and six grade II tumors, in addition to three normal tissue controls. Results showed that 25 genes that were primarily associated with apoptosis and angiogenesis functions were downregulated and 13 genes frequently involving DNA damage repair functions were upregulated. In addition to the inactivation of the neurofibromin gene, NF2, which is considered to be an early step in tumorigenesis, variations of other biological regulatory pathways may play a significant role in the development of meningioma. PMID:23946817

  13. Gene expression analysis of aberrant signaling pathways in meningiomas.

    PubMed

    Torres-Martín, Miguel; Martinez-Glez, Victor; Peña-Granero, Carolina; Isla, Alberto; Lassaletta, Luis; DE Campos, Jose M; Pinto, Giovanny R; Burbano, Rommel R; Meléndez, Bárbara; Castresana, Javier S; Rey, Juan A

    2013-07-01

    Examining aberrant pathway alterations is one method for understanding the abnormal signals that are involved in tumorigenesis and tumor progression. In the present study, expression arrays were performed on tumor-related genes in meningiomas. The GE Array Q Series HS-006 was used to determine the expression levels of 96 genes that corresponded to six primary biological regulatory pathways in a series of 42 meningiomas, including 32 grade I, four recurrent grade I and six grade II tumors, in addition to three normal tissue controls. Results showed that 25 genes that were primarily associated with apoptosis and angiogenesis functions were downregulated and 13 genes frequently involving DNA damage repair functions were upregulated. In addition to the inactivation of the neurofibromin gene, NF2, which is considered to be an early step in tumorigenesis, variations of other biological regulatory pathways may play a significant role in the development of meningioma. PMID:23946817

  14. RNAi Induces Innate Immunity through Multiple Cellular Signaling Pathways

    PubMed Central

    Wu, Jun; Pei, Rongjuan; Xu, Yang; Yang, Dongliang; Roggendorf, Michael; Lu, Mengji

    2013-01-01

    Background & Aims Our previous results showed that the knockdown of woodchuck hepatitis virus (WHV) by RNA interference (RNAi) led to upregulation of interferon stimulated genes (ISGs) in primary hepatocytes. In the present study, we tested the hypothesis that the cellular signaling pathways recognizing RNA molecules may be involved the ISG stimulation by RNAi. Methods Primary murine hepatocytes (PMHs) from wild type mice and WHV transgenic (Tg) mice were prepared and treated with defined siRNAs. The mRNA levels of target genes and ISGs were detected by real-time RT-PCR. The involvement of the signaling pathways including RIG-I/MDA5, PKR, and TLR3/7/8/9 was examined by specific inhibition and the analysis of their activation by Western blotting. Results In PMHs from WHV Tg mice, specific siRNAs targeting WHV, mouse β-actin, and GAPDH reduced the levels of targeted mRNAs and increased the mRNA expression of IFN-β, MxA, and IP-10. The enhanced ISG expression by siRNA transfection were abolished by siRNA-specific 2′-O-methyl antisense RNA and the inhibitors 2-AP and chloroquine blocking PKR and other TLR-mediated signaling pathways. Furthermore, Western blotting revealed that RNAi results in an increase in PKR phosphorylation and nuclear translocation of IRF3 and NF-êB, indicating the possible role of IRF3 in the RNAi-directed induction of ISGs. In contrast, silencing of RIG-I and MDA5 failed to block RNAi-mediated MxA induction. Conclusions RNAi is capable of enhancing innate immune responses through the PKR- and TLR-dependent signaling pathways in primary hepatocytes. The immune stimulation by RNAi may contribute to the antiviral activity of siRNAs in vivo. PMID:23700487

  15. PI3K/Akt signalling pathway and cancer.

    PubMed

    Fresno Vara, Juan Angel; Casado, Enrique; de Castro, Javier; Cejas, Paloma; Belda-Iniesta, Cristóbal; González-Barón, Manuel

    2004-04-01

    Phosphatidylinositol-3 kinases, PI3Ks, constitute a lipid kinase family characterized by their ability to phosphorylate inositol ring 3'-OH group in inositol phospholipids to generate the second messenger phosphatidylinositol-3,4,5-trisphosphate (PI-3,4,5-P(3)). RPTK activation results in PI(3,4,5)P(3) and PI(3,4)P(2) production by PI3K at the inner side of the plasma membrane. Akt interacts with these phospholipids, causing its translocation to the inner membrane, where it is phosphorylated and activated by PDK1 and PDK2. Activated Akt modulates the function of numerous substrates involved in the regulation of cell survival, cell cycle progression and cellular growth. In recent years, it has been shown that PI3K/Akt signalling pathway components are frequently altered in human cancers. Cancer treatment by chemotherapy and gamma-irradiation kills target cells primarily by the induction of apoptosis. However, the development of resistance to therapy is an important clinical problem. Failure to activate the apoptotic programme represents an important mode of drug resistance in tumor cells. Survival signals induced by several receptors are mediated mainly by PI3K/Akt, hence this pathway may decisively contribute to the resistant phenotype. Many of the signalling pathways involved in cellular transformation have been elucidated and efforts are underway to develop treatment strategies that target these specific signalling molecules or their downstream effectors. The PI3K/Akt pathway is involved in many of the mechanisms targeted by these new drugs, thus a better understanding of this crossroad can help to fully exploit the potential benefits of these new agents. PMID:15023437

  16. Regression of Pathological Cardiac Hypertrophy: Signaling Pathways and Therapeutic Targets

    PubMed Central

    Hou, Jianglong; Kang, Y. James

    2012-01-01

    Pathological cardiac hypertrophy is a key risk factor for heart failure. It is associated with increased interstitial fibrosis, cell death and cardiac dysfunction. The progression of pathological cardiac hypertrophy has long been considered as irreversible. However, recent clinical observations and experimental studies have produced evidence showing the reversal of pathological cardiac hypertrophy. Left ventricle assist devices used in heart failure patients for bridging to transplantation not only improve peripheral circulation but also often cause reverse remodeling of the geometry and recovery of the function of the heart. Dietary supplementation with physiologically relevant levels of copper can reverse pathological cardiac hypertrophy in mice. Angiogenesis is essential and vascular endothelial growth factor (VEGF) is a constitutive factor for the regression. The action of VEGF is mediated by VEGF receptor-1, whose activation is linked to cyclic GMP-dependent protein kinase-1 (PKG-1) signaling pathways, and inhibition of cyclic GMP degradation leads to regression of pathological cardiac hypertrophy. Most of these pathways are regulated by hypoxia-inducible factor. Potential therapeutic targets for promoting the regression include: promotion of angiogenesis, selective enhancement of VEGF receptor-1 signaling pathways, stimulation of PKG-1 pathways, and sustention of hypoxia-inducible factor transcriptional activity. More exciting insights into the regression of pathological cardiac hypertrophy are emerging. The time of translating the concept of regression of pathological cardiac hypertrophy to clinical practice is coming. PMID:22750195

  17. Color signals through dorsal and ventral visual pathways

    PubMed Central

    Conway, Bevil R.

    2014-01-01

    Explanations for color phenomena are often sought in the retina, LGN and V1, yet it is becoming increasingly clear that a complete account will take us further along the visual-processing pathway. Working out which areas are involved is not trivial. Responses to S-cone activation are often assumed to indicate that an area or neuron is involved in color perception. However, work tracing S-cone signals into extrastriate cortex has challenged this assumption: S-cone responses have been found in brain regions, such as MT, not thought to play a major role in color perception. Here we review the processing of S-cone signals across cortex and present original data on S-cone responses measured with fMRI in alert macaque, focusing on one area in which S-cone signals seem likely to contribute to color (V4/posterior inferior temporal cortex), and on one area in which S signals are unlikely to play a role in color (MT). We advance a hypothesis that the S-cone signals in color-computing areas are required to achieve a balanced neural representation of perceptual color space, while the S-cone signals in non-color-areas provide a cue to illumination (not luminance) and confer sensitivity to the chromatic contrast generated by natural daylight (shadows, illuminated by ambient sky, surrounded by direct sunlight). This sensitivity would facilitate the extraction of shape-from-shadow signals to benefit global scene analysis and motion perception. PMID:24103417

  18. Extreme-longevity mutations orchestrate silencing of multiple signaling pathways.

    PubMed

    Shmookler Reis, Robert J; Bharill, Puneet; Tazearslan, Cagdas; Ayyadevara, Srinivas

    2009-10-01

    Long-lived mutants provide unique insights into the genetic factors that limit lifespan in wild-type animals. Most mutants and RNA interference targets found to extend life, typically by 1.5- to 2.5-fold, were discovered in C. elegans. Several longevity-assurance pathways are conserved across widely divergent taxa, indicating that mechanisms of lifespan regulation evolved several hundred million years ago. Strong mutations to the C. elegans gene encoding AGE-1/PI3KCS achieve unprecedented longevity by orchestrating the modulation (predominantly silencing) of multiple signaling pathways. This is evident in a profound attenuation of total kinase activity, leading to reduced phosphoprotein content. Mutations to the gene encoding the catalytic subunit of PI3K (phosphatidylinositol 3-kinase) have the potential to modulate all enzymes that depend on its product, PIP3, for membrane tethering or activation by other kinases. Remarkably, strong mutants inactivating PI3K also silence multiple signaling pathways at the transcript level, partially but not entirely mediated by the DAF-16/FOXO transcription factor. Mammals have a relatively large proportion of somatic cells, and survival depends on their replication, whereas somatic cell divisions in nematodes are limited to development and reproductive tissues. Thus, translation of longevity gains from nematodes to mammals requires disentangling the downstream consequences of signaling mutations, to avoid their deleterious consequences.

  19. Pathways for virus assembly around nucleic acids

    PubMed Central

    Perlmutter, Jason D; Perkett, Matthew R

    2014-01-01

    Understanding the pathways by which viral capsid proteins assemble around their genomes could identify key intermediates as potential drug targets. In this work we use computer simulations to characterize assembly over a wide range of capsid protein-protein interaction strengths and solution ionic strengths. We find that assembly pathways can be categorized into two classes, in which intermediates are either predominantly ordered or disordered. Our results suggest that estimating the protein-protein and the protein-genome binding affinities may be sufficient to predict which pathway occurs. Furthermore, the calculated phase diagrams suggest that knowledge of the dominant assembly pathway and its relationship to control parameters could identify optimal strategies to thwart or redirect assembly to block infection. Finally, analysis of simulation trajectories suggests that the two classes of assembly pathways can be distinguished in single molecule fluorescence correlation spectroscopy or bulk time resolved small angle x-ray scattering experiments. PMID:25036288

  20. Signaling through Rho GTPase pathway as viable drug target.

    PubMed

    Lu, Qun; Longo, Frank M; Zhou, Huchen; Massa, Stephen M; Chen, Yan-Hua

    2009-01-01

    Signaling through the Rho family of small GTPases has been increasingly investigated for their involvement in a wide variety of diseases such as cardiovascular, pulmonary, and neurological disorders as well as cancer. Rho GTPases are a subfamily of the Ras superfamily proteins which play essential roles in a number of biological processes, especially in the regulation of cell shape change, cytokinesis, cell adhesion, and cell migration. Many of these processes demonstrate a common theme: the rapid and dynamic reorganization of actin cytoskeleton of which Rho signaling has now emerged as a major switch control. The involvement of dynamic changes of Rho GTPases in disease states underscores the need to produce effective inhibitors for their therapeutic applications. Fasudil and Y-27632, with many newer additions, are two classes of widely used chemical compounds that inhibit Rho kinase (ROCK), an important downstream effector of RhoA subfamily GTPases. These inhibitors have been successful in many preclinical studies, indicating the potential benefit of clinical Rho pathway inhibition. On the other hand, except for Rac1 inhibitor NSC23766, there are few effective inhibitors directly targeting Rho GTPases, likely due to the lack of optimal structural information on individual Rho-RhoGEF, Rho-RhoGAP, or Rho-RhoGDI interaction to achieve specificity. Recently, LM11A-31 and other derivatives of peptide mimetic ligands for p75 neurotrophin receptor (p75(NTR)) show promising effects upstream of Rho GTPase signaling in neuronal regeneration. CCG-1423, a chemical compound showing profiles of inhibiting downstream of RhoA, is a further attempt for the development of novel pharmacological tools to disrupt Rho signaling pathway in cancer. Because of a rapidly growing number of studies deciphering the role of the Rho proteins in many diseases, specific and potent pharmaceutical modulators of various steps of Rho GTPase signaling pathway are critically needed to target for

  1. Multiplicity and plasticity of natural killer cell signaling pathways

    PubMed Central

    Chiesa, Sabrina; Mingueneau, Michael; Fuseri, Nicolas; Malissen, Bernard; Raulet, David H.; Malissen, Marie; Vivier, Eric; Tomasello, Elena

    2006-01-01

    Natural killer (NK) cells express an array of activating receptors that associate with DAP12 (KARAP), CD3ζ, and/or FcRγ ITAM (immunoreceptor tyrosine-based activation motif)–bearing signaling subunits. In T and mast cells, ITAM-dependent signals are integrated by critical scaffolding elements such as LAT (linker for activation of T cells) and NTAL (non–T-cell activation linker). Using mice that are deficient for ITAM-bearing molecules, LAT or NTAL, we show that NK cell cytotoxicity and interferon-γ secretion are initiated by ITAM-dependent and -independent as well as LAT/NTAL-dependent and -independent pathways. The role of these various signaling circuits depends on the target cell as well as on the activation status of the NK cell. The multiplicity and the plasticity of the pathways that initiate NK cell effector functions contrast with the situation in T cells and B cells and provide an explanation for the resiliency of NK cell effector functions to various pharmacologic inhibitors and genetic mutations in signaling molecules. PMID:16291591

  2. Signaling Pathways and Gene Regulatory Networks in Cardiomyocyte Differentiation

    PubMed Central

    Parikh, Abhirath; Wu, Jincheng; Blanton, Robert M.

    2015-01-01

    Strategies for harnessing stem cells as a source to treat cell loss in heart disease are the subject of intense research. Human pluripotent stem cells (hPSCs) can be expanded extensively in vitro and therefore can potentially provide sufficient quantities of patient-specific differentiated cardiomyocytes. Although multiple stimuli direct heart development, the differentiation process is driven in large part by signaling activity. The engineering of hPSCs to heart cell progeny has extensively relied on establishing proper combinations of soluble signals, which target genetic programs thereby inducing cardiomyocyte specification. Pertinent differentiation strategies have relied as a template on the development of embryonic heart in multiple model organisms. Here, information on the regulation of cardiomyocyte development from in vivo genetic and embryological studies is critically reviewed. A fresh interpretation is provided of in vivo and in vitro data on signaling pathways and gene regulatory networks (GRNs) underlying cardiopoiesis. The state-of-the-art understanding of signaling pathways and GRNs presented here can inform the design and optimization of methods for the engineering of tissues for heart therapies. PMID:25813860

  3. SEPT4 is regulated by the Notch signaling pathway.

    PubMed

    Liu, Wenbin

    2012-04-01

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

  4. Two distinct signaling pathways participate in auxin-induced swelling of pea epidermal protoplasts.

    PubMed

    Yamagami, Mutsumi; Haga, Ken; Napier, Richard M; Iino, Moritoshi

    2004-02-01

    Protoplast swelling was used to investigate auxin signaling in the growth-limiting stem epidermis. The protoplasts of epidermal cells were isolated from elongating internodes of pea (Pisum sativum). These protoplasts swelled in response to auxin, providing the clearest evidence that the epidermis can directly perceive auxin. The swelling response to the natural auxin IAA showed a biphasic dose response curve but that to the synthetic auxin 1-naphthalene acetic acid (NAA) showed a simple bell-shaped dose response curve. The responses to IAA and NAA were further analyzed using antibodies raised against ABP1 (auxin-binding protein 1), and their dependency on extracellular ions was investigated. Two signaling pathways were resolved for IAA, an ABP1-dependent pathway and an ABP1-independent pathway that is much more sensitive to IAA than the former. The response by the ABP1 pathway was eliminated by anti-ABP1 antibodies, had a higher sensitivity to NAA, and did not depend on extracellular Ca(2+). In contrast, the response by the non-ABP1 pathway was not affected by anti-ABP1 antibodies, had no sensitivity to NAA, and depended on extracellular Ca(2+). The swelling by either pathway required extracellular K(+) and Cl(-). The auxin-induced growth of pea internode segments showed similar response patterns, including the occurrence of two peaks in the dose response curve for IAA and the difference in Ca(2+) requirements. It is suggested that two signaling pathways participate in auxin-induced internode growth and that the non-ABP1 pathway is more likely to be involved in the control of growth by constitutive concentrations of endogenous auxin. PMID:14764902

  5. Two Distinct Signaling Pathways Participate in Auxin-Induced Swelling of Pea Epidermal Protoplasts

    PubMed Central

    Yamagami, Mutsumi; Haga, Ken; Napier, Richard M.; Iino, Moritoshi

    2004-01-01

    Protoplast swelling was used to investigate auxin signaling in the growth-limiting stem epidermis. The protoplasts of epidermal cells were isolated from elongating internodes of pea (Pisum sativum). These protoplasts swelled in response to auxin, providing the clearest evidence that the epidermis can directly perceive auxin. The swelling response to the natural auxin IAA showed a biphasic dose response curve but that to the synthetic auxin 1-naphthalene acetic acid (NAA) showed a simple bell-shaped dose response curve. The responses to IAA and NAA were further analyzed using antibodies raised against ABP1 (auxin-binding protein 1), and their dependency on extracellular ions was investigated. Two signaling pathways were resolved for IAA, an ABP1-dependent pathway and an ABP1-independent pathway that is much more sensitive to IAA than the former. The response by the ABP1 pathway was eliminated by anti-ABP1 antibodies, had a higher sensitivity to NAA, and did not depend on extracellular Ca2+. In contrast, the response by the non-ABP1 pathway was not affected by anti-ABP1 antibodies, had no sensitivity to NAA, and depended on extracellular Ca2+. The swelling by either pathway required extracellular K+ and Cl–. The auxin-induced growth of pea internode segments showed similar response patterns, including the occurrence of two peaks in the dose response curve for IAA and the difference in Ca2+ requirements. It is suggested that two signaling pathways participate in auxin-induced internode growth and that the non-ABP1 pathway is more likely to be involved in the control of growth by constitutive concentrations of endogenous auxin. PMID:14764902

  6. Exploring De Novo metabolic pathways from pyruvate to propionic acid.

    PubMed

    Stine, Andrew; Zhang, Miaomin; Ro, Soo; Clendennen, Stephanie; Shelton, Michael C; Tyo, Keith E J; Broadbelt, Linda J

    2016-03-01

    Industrial biotechnology provides an efficient, sustainable solution for chemical production. However, designing biochemical pathways based solely on known reactions does not exploit its full potential. Enzymes are known to accept non-native substrates, which may allow novel, advantageous reactions. We have previously developed a computational program named Biological Network Integrated Computational Explorer (BNICE) to predict promiscuous enzyme activities and design synthetic pathways, using generalized reaction rules curated from biochemical reaction databases. Here, we use BNICE to design pathways synthesizing propionic acid from pyruvate. The currently known natural pathways produce undesirable by-products lactic acid and succinic acid, reducing their economic viability. BNICE predicted seven pathways containing four reaction steps or less, five of which avoid these by-products. Among the 16 biochemical reactions comprising these pathways, 44% were validated by literature references. More than 28% of these known reactions were not in the BNICE training dataset, showing that BNICE was able to predict novel enzyme substrates. Most of the pathways included the intermediate acrylic acid. As acrylic acid bioproduction has been well advanced, we focused on the critical step of reducing acrylic acid to propionic acid. We experimentally validated that Oye2p from Saccharomyces cerevisiae can catalyze this reaction at a slow turnover rate (10(-3) s(-1) ), which was unknown to occur with this enzyme, and is an important finding for further propionic acid metabolic engineering. These results validate BNICE as a pathway-searching tool that can predict previously unknown promiscuous enzyme activities and show that computational methods can elucidate novel biochemical pathways for industrial applications. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:303-311, 2016. PMID:26821575

  7. Pentagone internalises glypicans to fine-tune multiple signalling pathways

    PubMed Central

    Norman, Mark; Vuilleumier, Robin; Springhorn, Alexander; Gawlik, Jennifer; Pyrowolakis, George

    2016-01-01

    Tight regulation of signalling activity is crucial for proper tissue patterning and growth. Here we investigate the function of Pentagone (Pent), a secreted protein that acts in a regulatory feedback during establishment and maintenance of BMP/Dpp morphogen signalling during Drosophila wing development. We show that Pent internalises the Dpp co-receptors, the glypicans Dally and Dally-like protein (Dlp), and propose that this internalisation is important in the establishment of a long range Dpp gradient. Pent-induced endocytosis and degradation of glypicans requires dynamin- and Rab5, but not clathrin or active BMP signalling. Thus, Pent modifies the ability of cells to trap and transduce BMP by fine-tuning the levels of the BMP reception system at the plasma membrane. In addition, and in accordance with the role of glypicans in multiple signalling pathways, we establish a requirement of Pent for Wg signalling. Our data propose a novel mechanism by which morphogen signalling is regulated. DOI: http://dx.doi.org/10.7554/eLife.13301.001 PMID:27269283

  8. Docosahexaenoic acid in neural signaling systems.

    PubMed

    Crawford, Michael A

    2006-01-01

    Docosahexaenoic acid has been conserved in neural signalling systems in the cephalopods, fish, amphibian, reptiles, birds, mammals, primates and humans. This extreme conservation, despite wide genomic changes over 500 million years, testifies to a uniqueness of this molecule in the brain. The brain selectively incorporates docosahexaenoic acid and its rate of incorporation into the developing brain has been shown to be greater than ten times more efficient than its synthesis from the omega 3 fatty acids of land plant origin. Data has now been published demonstrating a significant influence of dietary omega 3 fatty acids on neural gene expression. As docosahexaenoic acid is the only omega 3 fatty acid in the brain, it is likely that it is the ligand involved. The selective uptake, requirement for function and stimulation of gene expression would have conferred an advantage to a primate which separated from the chimpanzees in the forests and woodlands and sought a different ecological niche. In view of the paucity of docosahexaenoic acid in the land food chain it is likely that the advantage would have been gained from a lacustrine or marine coastal habitat with access to food rich in docosahexaenoic acid and the accessory micronutrients, such as iodine, zinc, copper, manganese and selenium, of importance in brain development and protection against peroxidation. Land agricultural development has, in recent time, come to dominate the human food chain. The decline in use and availability of aquatic resources is not considered important by Langdon (2006) as he considers the resource was not needed for human evolution and can be replaced from the terrestrial food chain. This notion is not supported by the biochemistry nor the molecular biology. He misses the point that the shoreline hypothesis is not just dependent on docosahexaenoic acid but also on the other accessory nutrients specifically required by the brain. Moreover he neglects the basic principle of Darwinian

  9. Signaling Pathways Involved in Lunar Dust Induced Cytotoxicity

    NASA Technical Reports Server (NTRS)

    Zhang, Ye; Lam, Chiu-Wing; Scully, Robert R.; Williams, Kyle; Zalesak, Selina; Wu, Honglu; James, John T.

    2014-01-01

    The Moon's surface is covered by a layer of fine, reactive dust. Lunar dust contain about 1-2% of very fine dust (< 3 micron), that is respirable. The habitable area of any lunar landing vehicle and outpost would inevitably be contaminated with lunar dust that could pose a health risk. The purpose of the study is to evaluate the toxicity of Apollo moon dust in rodents to assess the health risk of dust exposures to humans. One of the particular interests in the study is to evaluate dust-induced changes of the expression of fibrosis-related genes, and to identify specific signaling pathways involved in lunar dust-induced toxicity. F344 rats were exposed for 4 weeks (6h/d; 5d/wk) in nose-only inhalation chambers to concentrations of 0 (control air), 2.1, 6.1, 21, and 61 mg/m(exp 3) of lunar dust. Five rats per group were euthanized 1 day, 1 week, 1 month, and 3 months after the last inhalation exposure. The total RNAs were isolated from the blood or lung tissue after being lavaged, using the Qigen RNeasy kit. The Rat Fibrosis RT2 Profile PCR Array was used to profile the expression of 84 genes relevant to fibrosis. The genes with significant expression changes are identified and the gene expression data were further analyzed using IPA pathway analysis tool to determine the signaling pathways with significant changes.

  10. New insights into the regulation of plant immunity by amino acid metabolic pathways.

    PubMed

    Zeier, Jürgen

    2013-12-01

    Besides defence pathways regulated by classical stress hormones, distinct amino acid metabolic pathways constitute integral parts of the plant immune system. Mutations in several genes involved in Asp-derived amino acid biosynthetic pathways can have profound impact on plant resistance to specific pathogen types. For instance, amino acid imbalances associated with homoserine or threonine accumulation elevate plant immunity to oomycete pathogens but not to pathogenic fungi or bacteria. The catabolism of Lys produces the immune signal pipecolic acid (Pip), a cyclic, non-protein amino acid. Pip amplifies plant defence responses and acts as a critical regulator of plant systemic acquired resistance, defence priming and local resistance to bacterial pathogens. Asp-derived pyridine nucleotides influence both pre- and post-invasion immunity, and the catabolism of branched chain amino acids appears to affect plant resistance to distinct pathogen classes by modulating crosstalk of salicylic acid- and jasmonic acid-regulated defence pathways. It also emerges that, besides polyamine oxidation and NADPH oxidase, Pro metabolism is involved in the oxidative burst and the hypersensitive response associated with avirulent pathogen recognition. Moreover, the acylation of amino acids can control plant resistance to pathogens and pests by the formation of protective plant metabolites or by the modulation of plant hormone activity.

  11. Muscle redox signalling pathways in exercise. Role of antioxidants.

    PubMed

    Mason, Shaun A; Morrison, Dale; McConell, Glenn K; Wadley, Glenn D

    2016-09-01

    Recent research highlights the importance of redox signalling pathway activation by contraction-induced reactive oxygen species (ROS) and nitric oxide (NO) in normal exercise-related cellular and molecular adaptations in skeletal muscle. In this review, we discuss some potentially important redox signalling pathways in skeletal muscle that are involved in acute and chronic responses to contraction and exercise. Specifically, we discuss redox signalling implicated in skeletal muscle contraction force, mitochondrial biogenesis and antioxidant enzyme induction, glucose uptake and muscle hypertrophy. Furthermore, we review evidence investigating the impact of major exogenous antioxidants on these acute and chronic responses to exercise. Redox signalling pathways involved in adaptive responses in skeletal muscle to exercise are not clearly elucidated at present, and further research is required to better define important signalling pathways involved. Evidence of beneficial or detrimental effects of specific antioxidant compounds on exercise adaptations in muscle is similarly limited, particularly in human subjects. Future research is required to not only investigate effects of specific antioxidant compounds on skeletal muscle exercise adaptations, but also to better establish mechanisms of action of specific antioxidants in vivo. Although we feel it remains somewhat premature to make clear recommendations in relation to application of specific antioxidant compounds in different exercise settings, a bulk of evidence suggests that N-acetylcysteine (NAC) is ergogenic through its effects on maintenance of muscle force production during sustained fatiguing events. Nevertheless, a current lack of evidence from studies using performance tests representative of athletic competition and a potential for adverse effects with high doses (>70mg/kg body mass) warrants caution in its use for performance enhancement. In addition, evidence implicates high dose vitamin C (1g/day) and E

  12. Distinct purinergic signaling pathways in prepubescent mouse spermatogonia.

    PubMed

    Fleck, David; Mundt, Nadine; Bruentgens, Felicitas; Geilenkirchen, Petra; Machado, Patricia A; Veitinger, Thomas; Veitinger, Sophie; Lipartowski, Susanne M; Engelhardt, Corinna H; Oldiges, Marco; Spehr, Jennifer; Spehr, Marc

    2016-09-01

    Spermatogenesis ranks among the most complex, yet least understood, developmental processes. The physiological principles that control male germ cell development in mammals are notoriously difficult to unravel, given the intricate anatomy and complex endo- and paracrinology of the testis. Accordingly, we lack a conceptual understanding of the basic signaling mechanisms within the testis, which control the seminiferous epithelial cycle and thus govern spermatogenesis. Here, we address paracrine signal transduction in undifferentiated male germ cells from an electrophysiological perspective. We identify distinct purinergic signaling pathways in prepubescent mouse spermatogonia, both in vitro and in situ. ATP-a dynamic, widespread, and evolutionary conserved mediator of cell to cell communication in various developmental contexts-activates at least two different spermatogonial purinoceptor isoforms. Both receptors operate within nonoverlapping stimulus concentration ranges, display distinct response kinetics and, in the juvenile seminiferous cord, are uniquely expressed in spermatogonia. We further find that spermatogonia express Ca(2+)-activated large-conductance K(+) channels that appear to function as a safeguard against prolonged ATP-dependent depolarization. Quantitative purine measurements additionally suggest testicular ATP-induced ATP release, a mechanism that could increase the paracrine radius of initially localized signaling events. Moreover, we establish a novel seminiferous tubule slice preparation that allows targeted electrophysiological recordings from identified testicular cell types in an intact epithelial environment. This unique approach not only confirms our in vitro findings, but also supports the notion of purinergic signaling during the early stages of spermatogenesis. PMID:27574293

  13. The Gq signalling pathway inhibits brown and beige adipose tissue

    PubMed Central

    Klepac, Katarina; Kilić, Ana; Gnad, Thorsten; Brown, Loren M.; Herrmann, Beate; Wilderman, Andrea; Balkow, Aileen; Glöde, Anja; Simon, Katharina; Lidell, Martin E.; Betz, Matthias J.; Enerbäck, Sven; Wess, Jürgen; Freichel, Marc; Blüher, Matthias; König, Gabi; Kostenis, Evi; Insel, Paul A.; Pfeifer, Alexander

    2016-01-01

    Brown adipose tissue (BAT) dissipates nutritional energy as heat via the uncoupling protein-1 (UCP1) and BAT activity correlates with leanness in human adults. Here we profile G protein-coupled receptors (GPCRs) in brown adipocytes to identify druggable regulators of BAT. Twenty-one per cent of the GPCRs link to the Gq family, and inhibition of Gq signalling enhances differentiation of human and murine brown adipocytes. In contrast, activation of Gq signalling abrogates brown adipogenesis. We further identify the endothelin/Ednra pathway as an autocrine activator of Gq signalling in brown adipocytes. Expression of a constitutively active Gq protein in mice reduces UCP1 expression in BAT, whole-body energy expenditure and the number of brown-like/beige cells in white adipose tissue (WAT). Furthermore, expression of Gq in human WAT inversely correlates with UCP1 expression. Thus, our data indicate that Gq signalling regulates brown/beige adipocytes and inhibition of Gq signalling may be a novel therapeutic approach to combat obesity. PMID:26955961

  14. Capping protein integrates multiple MAMP signalling pathways to modulate actin dynamics during plant innate immunity.

    PubMed

    Li, Jiejie; Henty-Ridilla, Jessica L; Staiger, Benjamin H; Day, Brad; Staiger, Christopher J

    2015-01-01

    Plants and animals perceive diverse microbe-associated molecular patterns (MAMPs) via pattern recognition receptors and activate innate immune signalling. The actin cytoskeleton has been suggested as a target for innate immune signalling and a key transducer of cellular responses. However, the molecular mechanisms underlying actin remodelling and the precise functions of these rearrangements during innate immunity remain largely unknown. Here we demonstrate rapid actin remodelling in response to several distinct MAMP signalling pathways in plant epidermal cells. The regulation of actin dynamics is a convergence point for basal defence machinery, such as cell wall fortification and transcriptional reprogramming. Our quantitative analyses of actin dynamics and genetic studies reveal that MAMP-stimulated actin remodelling is due to the inhibition of capping protein (CP) by the signalling lipid, phosphatidic acid. In addition, CP promotes resistance against bacterial and fungal phytopathogens. These findings demonstrate that CP is a central target for the plant innate immune response. PMID:26018794

  15. Biphasic Role of Calcium in Mouse Sperm Capacitation Signaling Pathways

    PubMed Central

    Alvau, Antonio; Escoffier, Jessica; Krapf, Dario; Sánchez-Cárdenas, Claudia; Salicioni, Ana M.; Darszon, Alberto; Visconti, Pablo E.

    2016-01-01

    Mammalian sperm acquire fertilizing ability in the female tract in a process known as capacitation. At the molecular level, capacitation is associated with up-regulation of a cAMP-dependent pathway, changes in intracellular pH, intracellular Ca2+ and an increase in tyrosine phosphorylation. How these signaling systems interact during capacitation is not well understood. Results presented in this study indicate that Ca2+ ions have a biphasic role in the regulation of cAMP-dependent signaling. Media without added Ca2+ salts (nominal zero Ca2+) still contain micromolar concentrations of this ion. Sperm incubated in this medium did not undergo PKA activation or the increase in tyrosine phosphorylation suggesting that these phosphorylation pathways require Ca2+. However, chelation of the extracellular Ca2+ traces by EGTA induced both cAMP-dependent phosphorylation and the increase in tyrosine phosphorylation. The EGTA effect in nominal zero Ca2+ media was mimicked by two calmodulin antagonists, W7 and calmidazolium, and by the calcineurin inhibitor cyclosporine A. These results suggest that Ca2+ ions regulate sperm cAMP and tyrosine phosphorylation pathways in a biphasic manner and that some of its effects are mediated by calmodulin. Interestingly, contrary to wild type mouse sperm, sperm from CatSper1 KO mice underwent PKA activation and an increase in tyrosine phosphorylation upon incubation in nominal zero Ca2+ media. Therefore, sperm lacking Catsper Ca2+ channels behave as wild-type sperm incubated in the presence of EGTA. This latter result suggests that Catsper transports the Ca2+ involved in the regulation of cAMP-dependent and tyrosine phosphorylation pathways required for sperm capacitation. PMID:25597298

  16. Miltefosine Suppresses Hepatic Steatosis by Activating AMPK Signal Pathway

    PubMed Central

    Zhu, Yaqin; Tong, Xing; Li, Kexue; Bai, Hui; Li, Xiaoyu; Ben, Jingjing; Zhang, Hanwen; Yang, Qing; Chen, Qi

    2016-01-01

    Background and Purpose It has been accepted that AMPK (Adenosine monophosphate–activated protein kinase) activation exhibits many beneficial effects on glucolipid metabolism. Lysophosphatidylcholine (LPC) is an important lysophospholipid which can improve blood glucose levels in diabetic mice and attenuate inflammation by activating AMPK signal pathway in macrophages. Synthetic alkylphospholipids (ALPs), such as miltefosine, is used as an alternate of LPC for the clinical application. Here, we investigated whether miltefosine could have an impact on hepatic steatosis and related metabolic disorders. Experimental Approach Mice were fed with high fat diet (HFD) for 16 weeks to generate an obese model. Next, the obese mice were randomly divided into three groups: saline-treated and miltefosine-treated (2.5 or 5 mg/kg/d) groups. Miltefosine was intraperitoneally administrated into mice for additional 4 weeks plus HFD treatment. Key Results It was shown that miltefosine treatment could substantially improve glucose metabolism, prevented hepatic lipid accumulation, and inhibited liver inflammation in HFD-fed mice by activating AMPK signal pathway. In vitro, miltefosine stimulated AMPKα phosphorylation both in time and dose dependent manner and decreased lipid accumulation in liver cells. When a specific AMPK inhibitor compound C was used to treat mice, the antagonistic effects of miltefosine on HFD-induced mouse hyperlipidaemia and liver steatosis were abolished. Treatment with miltefosine also dramatically inhibited the HFD-induced liver inflammation in mice. Conclusions and Implications Here we demonstrated that miltefosine might be a new activator of AMPK signal pathway in vivo and in vitro and be useful for treatment of hepatic steatosis and related metabolic disorders. PMID:27681040

  17. Involvement of Notch1/Hes signaling pathway in ankylosing spondylitis

    PubMed Central

    Xu, Wei; Liang, Chao-Ge; Li, Yi-Fan; Ji, Yun-Han; Qiu, Wen-Jun; Tang, Xian-Zhong

    2015-01-01

    We aimed to investigate the role of Notch1/Hes signaling pathway in the pathogenesis of abnormal ossification of hip ligament in patients with ankylosing spondylitis (AS). 22 AS patients scheduled for artificial hip arthroplasty were randomly chosen as AS group. As controls, we used 4 patients diagnosed with transcervical fracture who underwent hip replacement surgery. Notch1 and Hes mRNA expressions were detected by real-time fluorescent quantitative polymerase chain reaction (RFQ-PCR). Immunohistochemistry (IHC) was used to detect Notch1 and Hes protein expression. Correlation analyses of Notch-l and Hes with AS-related clinical factors were conducted with spearman’s correlation analysis and partial correlation analysis. RFQ-PCR results showed significant differences in Notch1 and Hes mRNA expressions between AS group and the control group (all P < 0.05). IHC analysis further indicated positive nuclear signals of Notch1 and Hes protein, indicating functional activation of the Notch1 and Hes pathways. Semi-quantitative IHC showed a higher Notch1 and Hes expression levels in AS group compared to the control group (all P < 0.05). Correlation analysis suggested that Hes protein expression was positively associated with the clinical course of the disease in AS patients. In conclusion, Notch1 and Hes overexpression was clearly detected in hip joint ligaments of AS patients, Hes protein expression was associated with the clinical course of AS. Taken together, we suggest that signaling pathways mediated by Notch1-Hes may contribute to ligament ossification of hip joints in AS patients. PMID:26045779

  18. Multiparticle collision dynamics for diffusion-influenced signaling pathways

    NASA Astrophysics Data System (ADS)

    Strehl, R.; Rohlf, K.

    2016-08-01

    An efficient yet accurate simulation method for modeling diffusion-influenced reaction networks is presented. The method extends existing reactive multiparticle collision dynamics by incorporating species-dependent diffusion coefficients, and developing theoretical expressions for the reactant-dependent diffusion control. This off-lattice particle-based mesoscopic simulation tool is particularly suited for problems in which detailed descriptions of particle trajectories and local reactions are required. Numerical simulations of an intracellular signaling pathway for bacterial chemotaxis are carried out to validate our approach, and to demonstrate its efficiency.

  19. Signaling pathways mediating chemotaxis in the social amoeba, Dictyostelium discoideum.

    PubMed

    Willard, Stacey S; Devreotes, Peter N

    2006-09-01

    Chemotaxis, or cell migration guided by chemical cues, is critical for a multitude of biological processes in a diverse array of organisms. Dictyostelium discoideum amoebae rely on chemotaxis to find food and to survive starvation conditions, and we have taken advantage of this system to study the molecular regulation of this vital cell behavior. Previous work has identified phosphoinositide signaling as one mechanism which may contribute to directional sensing and actin polymerization during chemotaxis; a mechanism which is conserved in mammalian neutrophils. In this review, we will discuss recent data on genes and pathways governing directional sensing and actin polymerization, with a particular emphasis on contributions from our laboratory. PMID:16962888

  20. To build a synapse: signaling pathways in neuromuscular junction assembly

    PubMed Central

    Wu, Haitao; Xiong, Wen C.; Mei, Lin

    2010-01-01

    Synapses, as fundamental units of the neural circuitry, enable complex behaviors. The neuromuscular junction (NMJ) is a synapse type that forms between motoneurons and skeletal muscle fibers and that exhibits a high degree of subcellular specialization. Aided by genetic techniques and suitable animal models, studies in the past decade have brought significant progress in identifying NMJ components and assembly mechanisms. This review highlights recent advances in the study of NMJ development, focusing on signaling pathways that are activated by diffusible cues, which shed light on synaptogenesis in the brain and contribute to a better understanding of muscular dystrophy. PMID:20215342

  1. Neural differentiation from embryonic stem cells in vitro: An overview of the signaling pathways

    PubMed Central

    Chuang, Jen-Hua; Tung, Li-Chu; Lin, Yenshou

    2015-01-01

    Neurons derived from embryonic stem cells (ESCs) have gained great merit in both basic research and regenerative medicine. Here we review and summarize the signaling pathways that have been reported to be involved in the neuronal differentiation of ESCs, particularly those associated with in vitro differentiation. The inducers and pathways explored include retinoic acid, Wnt/β-catenin, transforming growth factor/bone morphogenetic protein, Notch, fibroblast growth factor, cytokine, Hedgehog, c-Jun N-terminal kinase/mitogen-activated protein kinase and others. Some other miscellaneous molecular factors that have been reported in the literature are also summarized and discussed. These include calcium, calcium receptor, calcineurin, estrogen receptor, Hox protein, ceramide, glycosaminioglycan, ginsenoside Rg1, opioids, two pore channel 2, nitric oxide, chemically defined medium, cell-cell interactions, and physical stimuli. The interaction or crosstalk between these signaling pathways and factors will be explored. Elucidating these signals in detail should make a significant contribution to future progress in stem cell biology and allow, for example, better comparisons to be made between differentiation in vivo and in vitro. Of equal importance, a comprehensive understanding of the pathways that are involved in the development of neurons from ESCs in vitro will also accelerate their application as part of translational medicine. PMID:25815127

  2. Notch signaling pathway and Cdx2 expression in the development of Barrett's esophagus.

    PubMed

    Tamagawa, Yuji; Ishimura, Norihisa; Uno, Goichi; Yuki, Takafumi; Kazumori, Hideaki; Ishihara, Shunji; Amano, Yuji; Kinoshita, Yoshikazu

    2012-06-01

    Cdx2 expression in esophageal stem cells induced by reflux bile acids may be an important factor for development of Barrett's esophagus, whereas Notch signaling is a molecular signaling pathway that plays an important role in the determination of cell differentiation. ATOH1 (a factor associated with Notch signaling) plays an important role in differentiation of stem cells into goblet cells. However, the relationship between the Notch signaling pathway and Cdx2 expression in the development of Barrett's esophagus has not been explored. The aim of this study was to investigate the interrelationship between Notch signaling and Cdx2 in esophageal epithelial cells. The expressions of Cdx2, MUC2, and intracellular signaling molecules related to Notch signaling (Notch1, Hes1, and ATOH1) were examined using real-time polymerase chain reaction (PCR) and immunohistochemical staining with biopsy specimens obtained from esophageal intestinal metaplasia (IM) with goblet cells (IM⁺) and columnar epithelium not accompanied by goblet cells (IM⁻). For in vitro experiments, we employed human esophageal epithelial cell lines (OE33, OE19, and Het-1A). After forced Cdx2 expression by applying a Cdx2 expression vector to the cells, changes in the expressions of Notch1, Hes1, ATOH1, Cdx2, and MUC2 were analyzed by real-time PCR and western blot analysis. Changes in expressions of Notch1, Hes1, ATOH1, Cdx2, and MUC2 in cells were analyzed following stimulation with bile acids in the presence or absence of Cdx2 blocking with Cdx2-siRNA. Suppressed Hes1 and enhanced ATOH1 and MUC2 expressions were identified in IM⁺ specimens. Forced expression of Cdx2 in cells suppressed Hes1, and enhanced ATOH1 and MUC2 expressions, whereas bile acids suppressed Hes1, and enhanced ATOH1, Cdx2, and MUC2 expressions. On the other hand, these effects were blocked by siRNA-based Cdx2 downregulation. Enhanced expression of Cdx2 by stimulation with bile acids may induce intestinal differentiation of

  3. 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.

  4. Lysophosphatidic acid and signaling in sensory neurons.

    PubMed

    Oude Elferink, Ronald P J; Bolier, Ruth; Beuers, Ulrich H

    2015-01-01

    Lysophosphatidic acid is a potent signaling lipid molecule that has initially been characterized as a growth factor. However, later studies have revealed many more functions such as modulation of cell shape, cell migration, prevention of apoptosis, platelet aggregation, wound healing, osteoclast differentiation, vasopressor activity, embryo implantation, angiogenesis, lung fibrosis, hair growth and more. The molecule mainly acts through the activation of a set of at least 6 G-protein-coupled receptors (LPA1-6), but intracellular LPA was also shown to signal through the activation of the nuclear receptor PPARγ. In this short review we discuss the recent observations which suggest that in pathological conditions LPA also modulates signaling in sensory neurons. Thus, LPA has been shown to play a role in the initiation of neuropathic pain and, more recently, a relation was observed between increased LPA levels in the circulation and cholestatic itch. The mechanism by which this occurs remains to be elucidated. This article is part of a Special Issue entitled Linking transcription to physiology in lipodomics. PMID:25218302

  5. Hypergravity Stimulates Osteoblast Proliferation Via Matrix-Integrin-Signaling Pathways

    NASA Technical Reports Server (NTRS)

    Vercoutere, W.; Parra, M.; Roden, C.; DaCosta, M.; Wing, A.; Damsky, C.; Holton, E.; Searby, N.; Globus, R.; Almeida, E.

    2003-01-01

    Extensive characterizations of the physiologic consequences of microgravity and gravity indicate that lack of weight-bearing may cause tissue atrophy through cellular and subcellular level mechanisms. We hypothesize that gravity is needed for the efficient transduction of cell growth and survival signals from the extra-cellular matrix (ECM) in mechanosensitive tissues. Recent work from our laboratory and from others shows that an increase of gravity increases bone cell growth and survival. We found that 50-g hypergravity stimulation increased osteoblast proliferation for cells grown on Collagen Type I and Fibronectin, but not on Laminin or uncoated plastic. This may be a tissue-specific response, because 50-g hypergravity stimulation caused no increase in proliferation for primary rat fibroblasts. These results combined with RT-PCR for all possible integrins indicate that beta1 integrin subunit may be involved. The osteoblast proliferation response on Collagen Type I was greater at 25-g than at 10-g or 50-g; 24-h duration of hypergravity was necessary to see an increase in proliferation. Survival was enhanced during hypergravity stimulation by the presence of matrix. Flow cytometry analysis indicated that cell cycle may be altered; BrdU incorporation in proliferating cells showed an increase in the number of actively dividing cells from about 60% at 1-g to over 90% at 25-g. To further investigate the molecular components involved, we applied fluorescence labeling of cytoskeletal and signaling molecules to cells after 2 to 30 minutes of hypergravity stimulation. While structural components did not appear to be altered, phosphorylation increased, indicating that signaling pathways may be activated. These data indicate that gravity mechanostimulation of osteoblast proliferation involves specific matrix-integrin signaling pathways which are sensitive to duration and g-level.

  6. Multispecific Drug Transporter Slc22a8 (Oat3) Regulates Multiple Metabolic and Signaling Pathways

    PubMed Central

    Wu, Wei; Jamshidi, Neema; Eraly, Satish A.; Liu, Henry C.; Bush, Kevin T.; Palsson, Bernhard O.

    2013-01-01

    Multispecific drug transporters of the solute carrier and ATP-binding cassette families are highly conserved through evolution, but their true physiologic role remains unclear. Analyses of the organic anion transporter 3 (OAT3; encoded by Slc22a8/Oat3, originally Roct) knockout mouse have confirmed its critical role in the renal handling of common drugs (e.g., antibiotics, antivirals, diuretics) and toxins. Previous targeted metabolomics of the knockout of the closely related Oat1 have demonstrated a central metabolic role, but the same approach with Oat3 failed to reveal a similar set of endogenous substrates. Nevertheless, the Oat3 knockout is the only Oat described so far with a physiologically significant phenotype, suggesting the disturbance of metabolic or signaling pathways. Here we analyzed global gene expression in Oat3 knockout tissue, which implicated OAT3 in phase I and phase II metabolism (drug metabolizing enzymes or DMEs), as well as signaling pathways. Metabolic reconstruction with the recently developed “mouse Recon1” supported the involvement of Oat3 in the aforementioned pathways. Untargeted metabolomics were used to determine whether the predicted metabolic alterations could be confirmed. Many significant changes were observed; several metabolites were tested for direct interaction with mOAT3, whereas others were supported by published data. Oat3 thus appears critical for the handling of phase I (hydroxylation) and phase II (glucuronidation) metabolites. Oat3 also plays a role in bioenergetic pathways (e.g., the tricarboxylic acid cycle), as well as those involving vitamins (e.g., folate), steroids, prostaglandins, gut microbiome products, uremic toxins, cyclic nucleotides, amino acids, glycans, and possibly hyaluronic acid. The data seemingly consistent with the Remote Sensing and Signaling Hypothesis (Ahn and Nigam, 2009; Wu et al., 2011), also suggests that Oat3 is essential for the handling of dietary flavonoids and antioxidants. PMID

  7. Impact of hepatitis B virus infection on hepatic metabolic signaling pathway.

    PubMed

    Shi, Yi-Xian; Huang, Chen-Jie; Yang, Zheng-Gang

    2016-09-28

    A growing body of epidemiologic research has demonstrated that metabolic derangement exists in patients with hepatitis B virus (HBV) infection, indicating that there are clinical associations between HBV infection and host metabolism. In order to understand the complex interplay between HBV and hepatic metabolism in greater depth, we systematically reviewed these alterations in different metabolic signaling pathways due to HBV infection. HBV infection interfered with most aspects of hepatic metabolic responses, including glucose, lipid, nucleic acid, bile acid and vitamin metabolism. Glucose and lipid metabolism is a particular focus due to the significant promotion of gluconeogenesis, glucose aerobic oxidation, the pentose phosphate pathway, fatty acid synthesis or oxidation, phospholipid and cholesterol biosynthesis affected by HBV. These altered metabolic pathways are involved in the pathological process of not only hepatitis B, but also metabolic disorders, increasing the occurrence of complications, such as hepatocellular carcinoma and liver steatosis. Thus, a clearer understanding of the hepatic metabolic pathways affected by HBV and its pathogenesis is necessary to develop more novel therapeutic strategies targeting viral eradication. PMID:27688657

  8. Impact of hepatitis B virus infection on hepatic metabolic signaling pathway.

    PubMed

    Shi, Yi-Xian; Huang, Chen-Jie; Yang, Zheng-Gang

    2016-09-28

    A growing body of epidemiologic research has demonstrated that metabolic derangement exists in patients with hepatitis B virus (HBV) infection, indicating that there are clinical associations between HBV infection and host metabolism. In order to understand the complex interplay between HBV and hepatic metabolism in greater depth, we systematically reviewed these alterations in different metabolic signaling pathways due to HBV infection. HBV infection interfered with most aspects of hepatic metabolic responses, including glucose, lipid, nucleic acid, bile acid and vitamin metabolism. Glucose and lipid metabolism is a particular focus due to the significant promotion of gluconeogenesis, glucose aerobic oxidation, the pentose phosphate pathway, fatty acid synthesis or oxidation, phospholipid and cholesterol biosynthesis affected by HBV. These altered metabolic pathways are involved in the pathological process of not only hepatitis B, but also metabolic disorders, increasing the occurrence of complications, such as hepatocellular carcinoma and liver steatosis. Thus, a clearer understanding of the hepatic metabolic pathways affected by HBV and its pathogenesis is necessary to develop more novel therapeutic strategies targeting viral eradication.

  9. Impact of hepatitis B virus infection on hepatic metabolic signaling pathway

    PubMed Central

    Shi, Yi-Xian; Huang, Chen-Jie; Yang, Zheng-Gang

    2016-01-01

    A growing body of epidemiologic research has demonstrated that metabolic derangement exists in patients with hepatitis B virus (HBV) infection, indicating that there are clinical associations between HBV infection and host metabolism. In order to understand the complex interplay between HBV and hepatic metabolism in greater depth, we systematically reviewed these alterations in different metabolic signaling pathways due to HBV infection. HBV infection interfered with most aspects of hepatic metabolic responses, including glucose, lipid, nucleic acid, bile acid and vitamin metabolism. Glucose and lipid metabolism is a particular focus due to the significant promotion of gluconeogenesis, glucose aerobic oxidation, the pentose phosphate pathway, fatty acid synthesis or oxidation, phospholipid and cholesterol biosynthesis affected by HBV. These altered metabolic pathways are involved in the pathological process of not only hepatitis B, but also metabolic disorders, increasing the occurrence of complications, such as hepatocellular carcinoma and liver steatosis. Thus, a clearer understanding of the hepatic metabolic pathways affected by HBV and its pathogenesis is necessary to develop more novel therapeutic strategies targeting viral eradication. PMID:27688657

  10. Impact of hepatitis B virus infection on hepatic metabolic signaling pathway

    PubMed Central

    Shi, Yi-Xian; Huang, Chen-Jie; Yang, Zheng-Gang

    2016-01-01

    A growing body of epidemiologic research has demonstrated that metabolic derangement exists in patients with hepatitis B virus (HBV) infection, indicating that there are clinical associations between HBV infection and host metabolism. In order to understand the complex interplay between HBV and hepatic metabolism in greater depth, we systematically reviewed these alterations in different metabolic signaling pathways due to HBV infection. HBV infection interfered with most aspects of hepatic metabolic responses, including glucose, lipid, nucleic acid, bile acid and vitamin metabolism. Glucose and lipid metabolism is a particular focus due to the significant promotion of gluconeogenesis, glucose aerobic oxidation, the pentose phosphate pathway, fatty acid synthesis or oxidation, phospholipid and cholesterol biosynthesis affected by HBV. These altered metabolic pathways are involved in the pathological process of not only hepatitis B, but also metabolic disorders, increasing the occurrence of complications, such as hepatocellular carcinoma and liver steatosis. Thus, a clearer understanding of the hepatic metabolic pathways affected by HBV and its pathogenesis is necessary to develop more novel therapeutic strategies targeting viral eradication.

  11. Activation of the TOR Signalling Pathway by Glutamine Regulates Insect Fecundity.

    PubMed

    Zhai, Yifan; Sun, Zhongxiang; Zhang, Jianqing; Kang, Kui; Chen, Jie; Zhang, Wenqing

    2015-01-01

    The target of rapamycin (TOR) positively controls cell growth in response to nutrients such as amino acids. However, research on the specific nutrients sensed by TOR is limited. Glutamine (Gln), a particularly important amino acid involved in metabolism in organisms, is synthesised and catalysed exclusively by glutamine synthetase (GS), and our previous studies have shown that Gln may regulate fecundity in vivo levels of the brown planthopper (BPH) Nilaparvata lugens. Until now, it has remained unclear whether Gln activates or inhibits the TOR signalling pathway. Here, we performed the combined analyses of iTRAQ (isobaric tags for relative and absolute quantification) and DGE (tag-based digital gene expression) data in N. lugens at the protein and transcript levels after GS RNAi, and we found that 52 pathways overlap, including the TOR pathway. We further experimentally demonstrate that Gln activates the TOR pathway by promoting the serine/threonine protein kinase AKT and inhibiting the 5'AMP-activated protein kinase AMPK phosphorylation activity in the pest. Furthermore, TOR regulates the fecundity of N. lugens probably by mediating vitellogenin (Vg) expression. This work is the first report that Gln activates the TOR pathway in vivo. PMID:26024507

  12. Activation of the TOR Signalling Pathway by Glutamine Regulates Insect Fecundity.

    PubMed

    Zhai, Yifan; Sun, Zhongxiang; Zhang, Jianqing; Kang, Kui; Chen, Jie; Zhang, Wenqing

    2015-05-29

    The target of rapamycin (TOR) positively controls cell growth in response to nutrients such as amino acids. However, research on the specific nutrients sensed by TOR is limited. Glutamine (Gln), a particularly important amino acid involved in metabolism in organisms, is synthesised and catalysed exclusively by glutamine synthetase (GS), and our previous studies have shown that Gln may regulate fecundity in vivo levels of the brown planthopper (BPH) Nilaparvata lugens. Until now, it has remained unclear whether Gln activates or inhibits the TOR signalling pathway. Here, we performed the combined analyses of iTRAQ (isobaric tags for relative and absolute quantification) and DGE (tag-based digital gene expression) data in N. lugens at the protein and transcript levels after GS RNAi, and we found that 52 pathways overlap, including the TOR pathway. We further experimentally demonstrate that Gln activates the TOR pathway by promoting the serine/threonine protein kinase AKT and inhibiting the 5'AMP-activated protein kinase AMPK phosphorylation activity in the pest. Furthermore, TOR regulates the fecundity of N. lugens probably by mediating vitellogenin (Vg) expression. This work is the first report that Gln activates the TOR pathway in vivo.

  13. Deoxynivalenol: signaling pathways and human exposure risk assessment--an update.

    PubMed

    Wang, Zhonghong; Wu, Qinghua; Kuča, Kamil; Dohnal, Vlastimil; Tian, Zhihong

    2014-11-01

    Deoxynivalenol (DON) is a group B trichothecene and a common contaminant of crops worldwide. This toxin is known to cause a spectrum of diseases in animals and humans such as vomiting and gastroenteritis. Importantly, DON could inhibit the synthesis of protein and nucleonic acid and induce cell apoptosis in eukaryote cells. The transduction of signaling pathways is involved in the underlying mechanism of the cytotoxicity of DON. Mitogen-activated protein kinase and Janus kinase/signal transducer and activator of transcription seem to be two important signaling pathways and induce the inflammatory response by modulating the binding activates of specific transcription factors. This review mainly discussed the toxic mechanism of DON from the vantage point of signaling pathways and also assessed the profiles of DON and its metabolites in humans. Importantly, we conducted a human exposure risk assessment of DON from cereals, cereal-based foods, vegetables, water, and animal-derived foods in different countries. Some regular patterns of DON occurrence in these countries are suggested based on an analysis of global contamination with DON. This review should provide further insight for the toxic mechanism study of DON and human exposure risk assessment, thereby facilitating mycotoxin control strategies. PMID:25199684

  14. Deoxynivalenol: signaling pathways and human exposure risk assessment--an update.

    PubMed

    Wang, Zhonghong; Wu, Qinghua; Kuča, Kamil; Dohnal, Vlastimil; Tian, Zhihong

    2014-11-01

    Deoxynivalenol (DON) is a group B trichothecene and a common contaminant of crops worldwide. This toxin is known to cause a spectrum of diseases in animals and humans such as vomiting and gastroenteritis. Importantly, DON could inhibit the synthesis of protein and nucleonic acid and induce cell apoptosis in eukaryote cells. The transduction of signaling pathways is involved in the underlying mechanism of the cytotoxicity of DON. Mitogen-activated protein kinase and Janus kinase/signal transducer and activator of transcription seem to be two important signaling pathways and induce the inflammatory response by modulating the binding activates of specific transcription factors. This review mainly discussed the toxic mechanism of DON from the vantage point of signaling pathways and also assessed the profiles of DON and its metabolites in humans. Importantly, we conducted a human exposure risk assessment of DON from cereals, cereal-based foods, vegetables, water, and animal-derived foods in different countries. Some regular patterns of DON occurrence in these countries are suggested based on an analysis of global contamination with DON. This review should provide further insight for the toxic mechanism study of DON and human exposure risk assessment, thereby facilitating mycotoxin control strategies.

  15. Validation of signalling pathways: Case study of the p16-mediated pathway.

    PubMed

    Akçay, Nimet İlke; Bashirov, Rza; Tüzmen, Şükrü

    2015-04-01

    p16 is recognized as a tumor suppressor gene due to the prevalence of its genetic inactivation in all types of human cancers. Additionally, p16 gene plays a critical role in controlling aging, regulating cellular senescence, detection and maintenance of DNA damage. The molecular mechanism behind these events involves p16-mediated signaling pathway (or p16- Rb pathway), the focus of our study. Understanding functional dependence between dynamic behavior of biological components involved in the p16-mediated pathway and aforesaid molecular-level events might suggest possible implications in the diagnosis, prognosis and treatment of human cancer. In the present work, we employ reverse-engineering approach to construct the most detailed computational model of p16-mediated pathway in higher eukaryotes. We implement experimental data from the literature to validate the model, and under various assumptions predict the dynamic behavior of p16 and other biological components by interpreting the simulation results. The quantitative model of p16-mediated pathway is created in a systematic manner in terms of Petri net technologies.

  16. Bimolecular decomposition pathways for carboxylic acids of relevance to biofuels.

    PubMed

    Clark, Jared M; Nimlos, Mark R; Robichaud, David J

    2015-01-22

    The bimolecular thermal reactions of carboxylic acids were studied using quantum mechanical molecular modeling. Previous work1 investigated the unimolecular decomposition of a variety of organic acids, including saturated, α,β-unsaturated, and β,γ-unsaturated acids, and showed that the type and position of the unsaturation resulted in unique branching ratios between dehydration and decarboxylation, [H2O]/[CO2]. In this work, the effect of bimolecular chemistry (water-acid and acid-acid) is considered with a representative of each acid class. In both cases, the strained 4-centered, unimolecular transition state, typical of most organic acids, is opened up to 6- or 8-centered bimolecular geometries. These larger structures lead to a reduction in the barrier heights (20-45%) of the thermal decomposition pathways for organic acids and an increase in the decomposition kinetics. In some cases, they even cause a shift in the branching ratio of the corresponding product slates.

  17. Signaling pathway cross talk in Alzheimer’s disease

    PubMed Central

    2014-01-01

    Numerous studies suggest energy failure and accumulative intracellular waste play a causal role in the pathogenesis of several neurodegenerative disorders and Alzheimer’s disease (AD) in particular. AD is characterized by extracellular amyloid deposits, intracellular neurofibrillary tangles, cholinergic deficits, synaptic loss, inflammation and extensive oxidative stress. These pathobiological changes are accompanied by significant behavioral, motor, and cognitive impairment leading to accelerated mortality. Currently, the potential role of several metabolic pathways associated with AD, including Wnt signaling, 5' adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), Sirtuin 1 (Sirt1, silent mating-type information regulator 2 homolog 1), and peroxisome proliferator-activated receptor gamma co-activator 1-α (PGC-1α) have widened, with recent discoveries that they are able to modulate several pathological events in AD. These include reduction of amyloid-β aggregation and inflammation, regulation of mitochondrial dynamics, and increased availability of neuronal energy. This review aims to highlight the involvement of these new set of signaling pathways, which we have collectively termed “anti-ageing pathways”, for their potentiality in multi-target therapies against AD where cellular metabolic processes are severely impaired. PMID:24679124

  18. Text mining for metabolic pathways, signaling cascades, and protein networks.

    PubMed

    Hoffmann, Robert; Krallinger, Martin; Andres, Eduardo; Tamames, Javier; Blaschke, Christian; Valencia, Alfonso

    2005-05-10

    The complexity of the information stored in databases and publications on metabolic and signaling pathways, the high throughput of experimental data, and the growing number of publications make it imperative to provide systems to help the researcher navigate through these interrelated information resources. Text-mining methods have started to play a key role in the creation and maintenance of links between the information stored in biological databases and its original sources in the literature. These links will be extremely useful for database updating and curation, especially if a number of technical problems can be solved satisfactorily, including the identification of protein and gene names (entities in general) and the characterization of their types of interactions. The first generation of openly accessible text-mining systems, such as iHOP (Information Hyperlinked over Proteins), provides additional functions to facilitate the reconstruction of protein interaction networks, combine database and text information, and support the scientist in the formulation of novel hypotheses. The next challenge is the generation of comprehensive information regarding the general function of signaling pathways and protein interaction networks. PMID:15886388

  19. Kinase Signaling in Apoptosis Induced by Saturated Fatty Acids in Pancreatic β-Cells.

    PubMed

    Šrámek, Jan; Němcová-Fürstová, Vlasta; Kovář, Jan

    2016-01-01

    Pancreatic β-cell failure and death is considered to be one of the main factors responsible for type 2 diabetes. It is caused by, in addition to hyperglycemia, chronic exposure to increased concentrations of fatty acids, mainly saturated fatty acids. Molecular mechanisms of apoptosis induction by saturated fatty acids in β-cells are not completely clear. It has been proposed that kinase signaling could be involved, particularly, c-Jun N-terminal kinase (JNK), protein kinase C (PKC), p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK), and Akt kinases and their pathways. In this review, we discuss these kinases and their signaling pathways with respect to their possible role in apoptosis induction by saturated fatty acids in pancreatic β-cells. PMID:27626409

  20. Kinase Signaling in Apoptosis Induced by Saturated Fatty Acids in Pancreatic β-Cells

    PubMed Central

    Šrámek, Jan; Němcová-Fürstová, Vlasta; Kovář, Jan

    2016-01-01

    Pancreatic β-cell failure and death is considered to be one of the main factors responsible for type 2 diabetes. It is caused by, in addition to hyperglycemia, chronic exposure to increased concentrations of fatty acids, mainly saturated fatty acids. Molecular mechanisms of apoptosis induction by saturated fatty acids in β-cells are not completely clear. It has been proposed that kinase signaling could be involved, particularly, c-Jun N-terminal kinase (JNK), protein kinase C (PKC), p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK), and Akt kinases and their pathways. In this review, we discuss these kinases and their signaling pathways with respect to their possible role in apoptosis induction by saturated fatty acids in pancreatic β-cells. PMID:27626409

  1. Root-Shoot Signaling crosstalk involved in the shoot growth promoting action of rhizospheric humic acids.

    PubMed

    Olaetxea, Maite; Mora, Verónica; García, Andrés Calderin; Santos, Leandro Azevedo; Baigorri, Roberto; Fuentes, Marta; Garnica, María; Berbara, Ricardo Luis Louro; Zamarreño, Angel Maria; Garcia-Mina, Jose M

    2016-01-01

    Numerous studies have shown the ability of humic substances to improve plant development. This action is normally reflected in an enhancement of crop yields and quality. However, the mechanisms responsible for this action of humic substances remain rather unknown. Our studies have shown that the shoot promoting action of sedimentary humic acids is dependent of its ability to increase root hydraulic conductivity through signaling pathways related to ABA, which in turn is affected in roots by humic acids in an IAA-NO dependent way. Furthermore, these studies also indicate that the primary action of humic acids in roots might also be physical, resulting from a transient mild stress caused by humic acids associated with a fouling-cleaning cycle of wall cell pores. Finally the role of alternative signal molecules, such as ROS, and corresponding signaling pathways are also discussed and modeled in the context of the above-mentioned framework. PMID:26966789

  2. Root-Shoot Signaling crosstalk involved in the shoot growth promoting action of rhizospheric humic acids

    PubMed Central

    Olaetxea, Maite; Mora, Verónica; García, Andrés Calderin; Santos, Leandro Azevedo; Baigorri, Roberto; Fuentes, Marta; Garnica, María; Berbara, Ricardo Luis Louro; Zamarreño, Angel Maria; Garcia-Mina, Jose M.

    2016-01-01

    ABSTRACT Numerous studies have shown the ability of humic substances to improve plant development. This action is normally reflected in an enhancement of crop yields and quality. However, the mechanisms responsible for this action of humic substances remain rather unknown. Our studies have shown that the shoot promoting action of sedimentary humic acids is dependent of its ability to increase root hydraulic conductivity through signaling pathways related to ABA, which in turn is affected in roots by humic acids in an IAA-NO dependent way. Furthermore, these studies also indicate that the primary action of humic acids in roots might also be physical, resulting from a transient mild stress caused by humic acids associated with a fouling-cleaning cycle of wall cell pores. Finally the role of alternative signal molecules, such as ROS, and corresponding signaling pathways are also discussed and modeled in the context of the above-mentioned framework. PMID:26966789

  3. 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

  4. Hydrolysis products generated by lipoprotein lipase and endothelial lipase differentially impact THP-1 macrophage cell signalling pathways.

    PubMed

    Essaji, Yasmin; Yang, Yanbo; Albert, Carolyn J; Ford, David A; Brown, Robert J

    2013-08-01

    Macrophages express lipoprotein lipase (LPL) and endothelial lipase (EL) within atherosclerotic plaques; however, little is known about how lipoprotein hydrolysis products generated by these lipases might affect macrophage cell signalling pathways. We hypothesized that hydrolysis products affect macrophage cell signalling pathways associated with atherosclerosis. To test our hypothesis, we incubated differentiated THP-1 macrophages with products from total lipoprotein hydrolysis by recombinant LPL or EL. Using antibody arrays, we found that the phosphorylation of six receptor tyrosine kinases and three signalling nodes--most associated with atherosclerotic processes--was increased by LPL derived hydrolysis products. EL derived hydrolysis products only increased the phosphorylation of tropomyosin-related kinase A, which is also implicated in playing a role in atherosclerosis. Using electrospray ionization-mass spectrometry, we identified the species of triacylglycerols and phosphatidylcholines that were hydrolyzed by LPL and EL, and we identified the fatty acids liberated by gas chromatography-mass spectrometry. To determine if the total liberated fatty acids influenced signalling pathways, we incubated differentiated THP-1 macrophages with a mixture of the fatty acids that matched the concentrations of liberated fatty acids from total lipoproteins by LPL, and we subjected cell lysates to antibody array analyses. The analyses showed that only the phosphorylation of Akt was significantly increased in response to fatty acid treatment. Overall, our study shows that macrophages display potentially pro-atherogenic signalling responses following acute treatments with LPL and EL lipoprotein hydrolysis products. PMID:23794138

  5. Evolution of Abscisic Acid Synthesis and Signaling Mechanisms

    PubMed Central

    Hauser, Felix; Waadt, Rainer; Schroeder, Julian I.

    2011-01-01

    The plant hormone abscisic acid (ABA) mediates seed dormancy, controls seedling development and triggers tolerance to abiotic stresses, including drought. Core ABA signaling components consist of a recently identified group of ABA receptor proteins of the PYRABACTIN RESISTANCE (PYR)/REGULATORY COMPONENT OF ABA RECEPTOR (RCAR) family that act as negative regulators of members of the PROTEIN PHOSPHATASE 2C (PP2C) family. Inhibition of PP2C activity enables activation of SNF1-RELATED KINASE 2 (SnRK2) protein kinases, which target downstream components, including transcription factors, ion channels and NADPH oxidases. These and other components form a complex ABA signaling network. Here, an in depth analysis of the evolution of components in this ABA signaling network shows that (i) PYR/RCAR ABA receptor and ABF-type transcription factor families arose during land colonization of plants and are not found in algae and other species, (ii) ABA biosynthesis enzymes have evolved to plant- and fungal-specific forms, leading to different ABA synthesis pathways, (iii) existing stress signaling components, including PP2C phosphatases and SnRK kinases, were adapted for novel roles in this plant-specific network to respond to water limitation. In addition, evolutionarily conserved secondary structures in the PYR/RCAR ABA receptor family are visualized. PMID:21549957

  6. Romidepsin targets multiple survival signaling pathways in malignant T cells

    PubMed Central

    Valdez, B C; Brammer, J E; Li, Y; Murray, D; Liu, Y; Hosing, C; Nieto, Y; Champlin, R E; Andersson, B S

    2015-01-01

    Romidepsin is a cyclic molecule that inhibits histone deacetylases. It is Food and Drug Administration-approved for treatment of cutaneous and peripheral T-cell lymphoma, but its precise mechanism of action against malignant T cells is unknown. To better understand the biological effects of romidepsin in these cells, we exposed PEER and SUPT1 T-cell lines, and a primary sample from T-cell lymphoma patient (Patient J) to romidepsin. We then examined the consequences in some key oncogenic signaling pathways. Romidepsin displayed IC50 values of 10.8, 7.9 and 7.0 nm in PEER, SUPT1 and Patient J cells, respectively. Strong inhibition of histone deacetylases and demethylases, increased production of reactive oxygen species and decreased mitochondrial membrane potential were observed, which may contribute to the observed DNA-damage response and apoptosis. The stress-activated protein kinase/c-Jun N-terminal kinase signaling pathway and unfolded protein response in the endoplasmic reticulum were activated, whereas the phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) and β-catenin pro-survival pathways were inhibited. The decreased level of β-catenin correlated with the upregulation of its inhibitor SFRP1 through romidepsin-mediated hypomethylation of its gene promoter. Our results provide new insights into how romidepsin invokes malignant T-cell killing, show evidence of its associated DNA hypomethylating activity and offer a rationale for the development of romidepsin-containing combination therapies. PMID:26473529

  7. Romidepsin targets multiple survival signaling pathways in malignant T cells.

    PubMed

    Valdez, B C; Brammer, J E; Li, Y; Murray, D; Liu, Y; Hosing, C; Nieto, Y; Champlin, R E; Andersson, B S

    2015-10-16

    Romidepsin is a cyclic molecule that inhibits histone deacetylases. It is Food and Drug Administration-approved for treatment of cutaneous and peripheral T-cell lymphoma, but its precise mechanism of action against malignant T cells is unknown. To better understand the biological effects of romidepsin in these cells, we exposed PEER and SUPT1 T-cell lines, and a primary sample from T-cell lymphoma patient (Patient J) to romidepsin. We then examined the consequences in some key oncogenic signaling pathways. Romidepsin displayed IC50 values of 10.8, 7.9 and 7.0 nm in PEER, SUPT1 and Patient J cells, respectively. Strong inhibition of histone deacetylases and demethylases, increased production of reactive oxygen species and decreased mitochondrial membrane potential were observed, which may contribute to the observed DNA-damage response and apoptosis. The stress-activated protein kinase/c-Jun N-terminal kinase signaling pathway and unfolded protein response in the endoplasmic reticulum were activated, whereas the phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin (PI3K/AKT/mTOR) and β-catenin pro-survival pathways were inhibited. The decreased level of β-catenin correlated with the upregulation of its inhibitor SFRP1 through romidepsin-mediated hypomethylation of its gene promoter. Our results provide new insights into how romidepsin invokes malignant T-cell killing, show evidence of its associated DNA hypomethylating activity and offer a rationale for the development of romidepsin-containing combination therapies.

  8. Phosphate-responsive signaling pathway is a novel component of NAD+ metabolism in Saccharomyces cerevisiae.

    PubMed

    Lu, Shu-Ping; Lin, Su-Ju

    2011-04-22

    Nicotinamide adenine dinucleotide (NAD(+)) is an essential cofactor involved in various cellular biochemical reactions. To date the signaling pathways that regulate NAD(+) metabolism remain unclear due to the dynamic nature and complexity of the NAD(+) metabolic pathways and the difficulty of determining the levels of the interconvertible pyridine nucleotides. Nicotinamide riboside (NmR) is a key pyridine metabolite that is excreted and re-assimilated by yeast and plays important roles in the maintenance of NAD(+) pool. In this study we establish a NmR-specific reporter system and use it to identify yeast mutants with altered NmR/NAD(+) metabolism. We show that the phosphate-responsive signaling (PHO) pathway contributes to control NAD(+) metabolism. Yeast strains with activated PHO pathway show increases in both the release rate and internal concentration of NmR. We further identify Pho8, a PHO-regulated vacuolar phosphatase, as a potential NmR production factor. We also demonstrate that Fun26, a homolog of human ENT (equilibrative nucleoside transporter), localizes to the vacuolar membrane and establishes the size of the vacuolar and cytosolic NmR pools. In addition, the PHO pathway responds to depletion of cellular nicotinic acid mononucleotide (NaMN) and mediates nicotinamide mononucleotide (NMN) catabolism, thereby contributing to both NmR salvage and phosphate acquisition. Therefore, NaMN is a putative molecular link connecting the PHO signaling and NAD(+) metabolic pathways. Our findings may contribute to the understanding of the molecular basis and regulation of NAD(+) metabolism in higher eukaryotes. PMID:21349851

  9. Estrogen Signaling Multiple Pathways to Impact Gene Transcription

    PubMed Central

    Marino, Maria; Galluzzo, Paola; Ascenzi, Paolo

    2006-01-01

    Steroid hormones exert profound effects on cell growth, development, differentiation, and homeostasis. Their effects are mediated through specific intracellular steroid receptors that act via multiple mechanisms. Among others, the action mechanism starting upon 17β-estradiol (E2) binds to its receptors (ER) is considered a paradigmatic example of how steroid hormones function. Ligand-activated ER dimerizes and translocates in the nucleus where it recognizes specific hormone response elements located in or near promoter DNA regions of target genes. Behind the classical genomic mechanism shared with other steroid hormones, E2 also modulates gene expression by a second indirect mechanism that involves the interaction of ER with other transcription factors which, in turn, bind their cognate DNA elements. In this case, ER modulates the activities of transcription factors such as the activator protein (AP)-1, nuclear factor-κB (NF-κB) and stimulating protein-1 (Sp-1), by stabilizing DNA-protein complexes and/or recruiting co-activators. In addition, E2 binding to ER may also exert rapid actions that start with the activation of a variety of signal transduction pathways (e.g. ERK/MAPK, p38/MAPK, PI3K/AKT, PLC/PKC). The debate about the contribution of different ER-mediated signaling pathways to coordinate the expression of specific sets of genes is still open. This review will focus on the recent knowledge about the mechanism by which ERs regulate the expression of target genes and the emerging field of integration of membrane and nuclear receptor signaling, giving examples of the ways by which the genomic and non-genomic actions of ERs on target genes converge. PMID:18369406

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

    PubMed Central

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

    2015-01-01

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

  11. Phytochrome and retrograde signalling pathways coverage to antogonistically regulate a light-induced transcription network

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plastid-to-nucleus retrograde signals emitted by dysfunctional chloroplasts impact photomorphogenic development, but the molecular link between retrograde and photosensory-receptor signaling has remained undefined. Here, we show that the phytochrome (phy) and retrograde signaling pathways converge a...

  12. Phosphoproteomic Analyses Reveal Signaling Pathways That Facilitate Lytic Gammaherpesvirus Replication

    PubMed Central

    Stahl, James A.; Chavan, Shweta S.; Sifford, Jeffrey M.; MacLeod, Veronica; Voth, Daniel E.; Edmondson, Ricky D.; Forrest, J. Craig

    2013-01-01

    Lytic gammaherpesvirus (GHV) replication facilitates the establishment of lifelong latent infection, which places the infected host at risk for numerous cancers. As obligate intracellular parasites, GHVs must control and usurp cellular signaling pathways in order to successfully replicate, disseminate to stable latency reservoirs in the host, and prevent immune-mediated clearance. To facilitate a systems-level understanding of phosphorylation-dependent signaling events directed by GHVs during lytic replication, we utilized label-free quantitative mass spectrometry to interrogate the lytic replication cycle of murine gammaherpesvirus-68 (MHV68). Compared to controls, MHV68 infection regulated by 2-fold or greater ca. 86% of identified phosphopeptides – a regulatory scale not previously observed in phosphoproteomic evaluations of discrete signal-inducing stimuli. Network analyses demonstrated that the infection-associated induction or repression of specific cellular proteins globally altered the flow of information through the host phosphoprotein network, yielding major changes to functional protein clusters and ontologically associated proteins. A series of orthogonal bioinformatics analyses revealed that MAPK and CDK-related signaling events were overrepresented in the infection-associated phosphoproteome and identified 155 host proteins, such as the transcription factor c-Jun, as putative downstream targets. Importantly, functional tests of bioinformatics-based predictions confirmed ERK1/2 and CDK1/2 as kinases that facilitate MHV68 replication and also demonstrated the importance of c-Jun. Finally, a transposon-mutant virus screen identified the MHV68 cyclin D ortholog as a viral protein that contributes to the prominent MAPK/CDK signature of the infection-associated phosphoproteome. Together, these analyses enhance an understanding of how GHVs reorganize and usurp intracellular signaling networks to facilitate infection and replication. PMID:24068923

  13. Phosphoproteomic analyses reveal signaling pathways that facilitate lytic gammaherpesvirus replication.

    PubMed

    Stahl, James A; Chavan, Shweta S; Sifford, Jeffrey M; MacLeod, Veronica; Voth, Daniel E; Edmondson, Ricky D; Forrest, J Craig

    2013-09-01

    Lytic gammaherpesvirus (GHV) replication facilitates the establishment of lifelong latent infection, which places the infected host at risk for numerous cancers. As obligate intracellular parasites, GHVs must control and usurp cellular signaling pathways in order to successfully replicate, disseminate to stable latency reservoirs in the host, and prevent immune-mediated clearance. To facilitate a systems-level understanding of phosphorylation-dependent signaling events directed by GHVs during lytic replication, we utilized label-free quantitative mass spectrometry to interrogate the lytic replication cycle of murine gammaherpesvirus-68 (MHV68). Compared to controls, MHV68 infection regulated by 2-fold or greater ca. 86% of identified phosphopeptides - a regulatory scale not previously observed in phosphoproteomic evaluations of discrete signal-inducing stimuli. Network analyses demonstrated that the infection-associated induction or repression of specific cellular proteins globally altered the flow of information through the host phosphoprotein network, yielding major changes to functional protein clusters and ontologically associated proteins. A series of orthogonal bioinformatics analyses revealed that MAPK and CDK-related signaling events were overrepresented in the infection-associated phosphoproteome and identified 155 host proteins, such as the transcription factor c-Jun, as putative downstream targets. Importantly, functional tests of bioinformatics-based predictions confirmed ERK1/2 and CDK1/2 as kinases that facilitate MHV68 replication and also demonstrated the importance of c-Jun. Finally, a transposon-mutant virus screen identified the MHV68 cyclin D ortholog as a viral protein that contributes to the prominent MAPK/CDK signature of the infection-associated phosphoproteome. Together, these analyses enhance an understanding of how GHVs reorganize and usurp intracellular signaling networks to facilitate infection and replication.

  14. Peroxiredoxins in Regulation of MAPK Signalling Pathways; Sensors and Barriers to Signal Transduction

    PubMed Central

    Latimer, Heather R.; Veal, Elizabeth A.

    2016-01-01

    Peroxiredoxins are highly conserved and abundant peroxidases. Although the thioredoxin peroxidase activity of peroxiredoxin (Prx) is important to maintain low levels of endogenous hydrogen peroxide, Prx have also been shown to promote hydrogen peroxide-mediated signalling. Mitogen activated protein kinase (MAPK) signalling pathways mediate cellular responses to a variety of stimuli, including reactive oxygen species (ROS). Here we review the evidence that Prx can act as both sensors and barriers to the activation of MAPK and discuss the underlying mechanisms involved, focusing in particular on the relationship with thioredoxin. PMID:26813660

  15. Small molecules intercept Notch signaling and the early secretory pathway.

    PubMed

    Krämer, Andreas; Mentrup, Torben; Kleizen, Bertrand; Rivera-Milla, Eric; Reichenbach, Daniela; Enzensperger, Christoph; Nohl, Richard; Täuscher, Eric; Görls, Helmar; Ploubidou, Aspasia; Englert, Christoph; Werz, Oliver; Arndt, Hans-Dieter; Kaether, Christoph

    2013-11-01

    Notch signaling has a pivotal role in numerous cell-fate decisions, and its aberrant activity leads to developmental disorders and cancer. To identify molecules that influence Notch signaling, we screened nearly 17,000 compounds using automated microscopy to monitor the trafficking and processing of a ligand-independent Notch-enhanced GFP (eGFP) reporter. Characterization of hits in vitro by biochemical and cellular assays and in vivo using zebrafish led to five validated compounds, four of which induced accumulation of the reporter at the plasma membrane by inhibiting γ-secretase. One compound, the dihydropyridine FLI-06, disrupted the Golgi apparatus in a manner distinct from that of brefeldin A and golgicide A. FLI-06 inhibited general secretion at a step before exit from the endoplasmic reticulum (ER), which was accompanied by a tubule-to-sheet morphological transition of the ER, rendering FLI-06 the first small molecule acting at such an early stage in secretory traffic. These data highlight the power of phenotypic screening to enable investigations of central cellular signaling pathways. PMID:24077179

  16. Oncogenic mutant of Galpha12 stimulates cell proliferation through cycloxygenase-2 signaling pathway.

    PubMed

    Dermott, J M; Reddy, M R; Onesime, D; Reddy, E P; Dhanasekaran, N

    1999-12-01

    Expression of the GTPase-deficient, activated mutant alpha-subunit of the heterotrimeric G protein G12 (Galpha12QL) leads to the neoplastic transformation of fibroblast cell lines. The mitogenic pathway regulated by Galpha12QL includes an extensive signaling network involving several small GTPases and various kinases. In addition, Galpha12QL has been shown to potentiate the serum-induced phospholipase-A2 activity in NIH3T3 cells. In the present study, we demonstrate that cycloxygenase-2 (COX-2) pathway is involved in the mitogenic pathway activated by Galpha12QL. Expression of Galpha12QL and not Galpha13QL, stimulates the serum-induced release of arachidonic acid in NIH3T3 cells. Furthermore, expression of Galpha12QL or the stimulation of wild-type Galpha12 induces the expression of COX-2. Our results also indicate that the COX-2 inhibitor acutely disrupts the DNA-synthesis stimulated by Galpha12QL in NIH3T3 cells. These studies, for the first time, identify the crucial role of COX-2 in Galpha12-mediated regulation of cell proliferation and suggest a role for prostaglandin-derived autocrine loop in Galpha12-mediated signaling pathways. PMID:10602471

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

    SciTech Connect

    Borziak, Kirill; Jouline, Igor B

    2007-01-01

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

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

    PubMed Central

    Borziak, Kirill

    2016-01-01

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

  19. Inhibition of fatty acid synthase suppresses U-2 OS cell invasion and migration via downregulating the activity of HER2/PI3K/AKT signaling pathway in vitro

    SciTech Connect

    Wang, Tao Fang; Wang, Heng; Peng, Ai Fen; Luo, Qing Feng; Liu, Zhi Li; Zhou, Rong Ping; Gao, Song; Zhou, Yang; Chen, Wen Zhao

    2013-10-18

    Highlights: •We investigate the relationship between FASN and HER2 or p-HER2 by IHC in OS tissues. •We construct FASN-specific RNAi plasmid. •Inhibiting FASN down-regulates HER2/PI3K/AKT cell signaling in U-2 OS. •Inhibiting FASN blocks U-2 OS cell invasion and migration. -- Abstract: FASN plays an important role in the malignant phenotype of various tumors. Our previous studies show that inhibition FASN could induce apoptosis and inhibit proliferation in human osteosarcoma (OS) cell in vivo and vitro. The aim in this study was to investigate the effect of inhibition FASN on the activity of HER2/PI3K/AKT axis and invasion and migration of OS cell. The expression of FASN, HER2 and p-HER2(Y1248) proteins was detected by immunohistochemistry in OS tissues from 24 patients with pulmonary metastatic disease, and the relationship between FASN and p-HER2 as well as HER2 was investigated. The results showed that there was a positive correlation between FASN and HER2 as well as p-HER2 protein expression. The U-2 OS cells were transfected with either the FASN specific RNAi plasmid or the negative control RNAi plasmid. FASN mRNA was measured by RT-PCR. Western blot assays was performed to examine the protein expression of FASN, HER2, p-HER2(Y1248), PI3K, Akt and p-Akt (Ser473). Migration and invasion of cells were investigated by wound healing and transwell invasion assays. The results showed that the activity of HER2/PI3K/AKT signaling pathway was suppressed by inhibiting FASN. Meanwhile, the U-2OS cells migration and invasion were also impaired by inhibiting the activity of FASN/HER2/PI3K/AKT. Our results indicated that inhibition of FASN suppresses OS cell invasion and migration via down-regulation of the “HER2/PI3K/AKT” axis in vitro. FASN blocker may be a new therapeutic strategy in OS management.

  20. An enhanced functional interrogation/manipulation of intracellular signaling pathways with the peptide 'stapling' technology.

    PubMed

    He, Y; Chen, D; Zheng, W

    2015-11-12

    Specific protein-protein interactions (PPIs) constitute a key underlying mechanism for the presence of a multitude of intracellular signaling pathways, which are essential for the survival of normal and cancer cells. Specific molecular blockers for a crucial PPI would therefore be invaluable tools for an enhanced functional interrogation of the signaling pathway harboring this particular PPI. On the other hand, if a particular PPI is essential for the survival of cancer cells but is absent in or dispensable for the survival of normal cells, its specific molecular blockers could potentially be developed into effective anticancer therapeutics. Due to the flat and extended PPI interface, it would be conceivably difficult for small molecules to achieve an effective blockade, a problem which could be potentially circumvented with peptides or proteins. However, the well-documented proteolytic instability and cellular impermeability of peptides and proteins in general would make their developing into effective intracellular PPI blockers quite a challenge. With the advent of the peptide 'stapling' technology which was demonstrated to be able to stabilize the α-helical conformation of a peptide via bridging two neighboring amino-acid side chains with a 'molecular staple', a linear parent peptide could be transformed into a stronger PPI blocker with enhanced proteolytic stability and cellular permeability. This review will furnish an account on the peptide 'stapling' technology and its exploitation in efforts to achieve an enhanced functional interrogation or manipulation of intracellular signaling pathways especially those that are cancer relevant.

  1. Signaling pathways relevant to cognition-enhancing drug targets.

    PubMed

    Ménard, Caroline; Gaudreau, Pierrette; Quirion, Rémi

    2015-01-01

    Aging is generally associated with a certain cognitive decline. However, individual differences exist. While age-related memory deficits can be observed in humans and rodents in the absence of pathological conditions, some individuals maintain intact cognitive functions up to an advanced age. The mechanisms underlying learning and memory processes involve the recruitment of multiple signaling pathways and gene expression, leading to adaptative neuronal plasticity and long-lasting changes in brain circuitry. This chapter summarizes the current understanding of how these signaling cascades could be modulated by cognition-enhancing agents favoring memory formation and successful aging. It focuses on data obtained in rodents, particularly in the rat as it is the most common animal model studied in this field. First, we will discuss the role of the excitatory neurotransmitter glutamate and its receptors, downstream signaling effectors [e.g., calcium/calmodulin-dependent protein kinase II (CaMKII), protein kinase C (PKC), extracellular signal-regulated kinases (ERK), mammalian target of rapamycin (mTOR), cAMP response element-binding protein (CREB)], associated immediate early gene (e.g., Homer 1a, Arc and Zif268), and growth factors [insulin-like growth factors (IGFs) and brain-derived neurotrophic factor (BDNF)] in synaptic plasticity and memory formation. Second, the impact of the cholinergic system and related modulators on memory will be briefly reviewed. Finally, since dynorphin neuropeptides have recently been associated with memory impairments in aging, it is proposed as an attractive target to develop novel cognition-enhancing agents. PMID:25977080

  2. Kinetic insulation as an effective mechanism for achieving pathway specificity in intracellular signaling networks

    PubMed Central

    Behar, Marcelo; Dohlman, Henrik G.; Elston, Timothy C.

    2007-01-01

    Intracellular signaling pathways that share common components often elicit distinct physiological responses. In most cases, the biochemical mechanisms responsible for this signal specificity remain poorly understood. Protein scaffolds and cross-inhibition have been proposed as strategies to prevent unwanted cross-talk. Here, we report a mechanism for signal specificity termed “kinetic insulation.” In this approach signals are selectively transmitted through the appropriate pathway based on their temporal profile. In particular, we demonstrate how pathway architectures downstream of a common component can be designed to efficiently separate transient signals from signals that increase slowly over time. Furthermore, we demonstrate that upstream signaling proteins can generate the appropriate input to the common pathway component regardless of the temporal profile of the external stimulus. Our results suggest that multilevel signaling cascades may have evolved to modulate the temporal profile of pathway activity so that stimulus information can be efficiently encoded and transmitted while ensuring signal specificity. PMID:17913886

  3. Defective phosphatidic acid-phospholipase C signaling in diabetic cardiomyopathy.

    PubMed

    Tappia, Paramjit S; Maddaford, Thane G; Hurtado, Cecilia; Dibrov, Elena; Austria, J Alejandro; Sahi, Nidhi; Panagia, Vincenzo; Pierce, Grant N

    2004-03-26

    The effects of exogenous phosphatidic acid (PA) on Ca2+ transients and contractile activity were studied in cardiomyocytes isolated from chronic streptozotocin-induced diabetic rats. In control cells, 25 microM PA induced a significant increase in active cell shortening and Ca2+ transients. PA increased IP3 generation in the control cardiomyocytes and its inotropic effects were blocked by a phospholipase C inhibitor. In cardiomyocytes from diabetic rats, PA induced a 25% decrease in active cell shortening and no significant effect on Ca2+ transients. Basal and PA-induced IP3 generation in diabetic rat cardiomyocytes was 3-fold lower as compared to control cells. Sarcolemmal membrane PLC activity was impaired. Insulin treatment of the diabetic animals resulted in a partial recovery of PA responses. Our results, therefore, identify an important defect in the PA-PLC signaling pathway in diabetic rat cardiomyocytes, which may have significant implications for heart dysfunction during diabetes. PMID:15003542

  4. Defective phosphatidic acid-phospholipase C signaling in diabetic cardiomyopathy.

    PubMed

    Tappia, Paramjit S; Maddaford, Thane G; Hurtado, Cecilia; Dibrov, Elena; Austria, J Alejandro; Sahi, Nidhi; Panagia, Vincenzo; Pierce, Grant N

    2004-03-26

    The effects of exogenous phosphatidic acid (PA) on Ca2+ transients and contractile activity were studied in cardiomyocytes isolated from chronic streptozotocin-induced diabetic rats. In control cells, 25 microM PA induced a significant increase in active cell shortening and Ca2+ transients. PA increased IP3 generation in the control cardiomyocytes and its inotropic effects were blocked by a phospholipase C inhibitor. In cardiomyocytes from diabetic rats, PA induced a 25% decrease in active cell shortening and no significant effect on Ca2+ transients. Basal and PA-induced IP3 generation in diabetic rat cardiomyocytes was 3-fold lower as compared to control cells. Sarcolemmal membrane PLC activity was impaired. Insulin treatment of the diabetic animals resulted in a partial recovery of PA responses. Our results, therefore, identify an important defect in the PA-PLC signaling pathway in diabetic rat cardiomyocytes, which may have significant implications for heart dysfunction during diabetes.

  5. Distinct amino acid-sensing mTOR pathways regulate skeletal myogenesis.

    PubMed

    Yoon, Mee-Sup; Chen, Jie

    2013-12-01

    Signaling through the mammalian target of rapamycin (mTOR) in response to amino acid availability controls many cellular and developmental processes. mTOR is a master regulator of myogenic differentiation, but the pathways mediating amino acid signals in this process are not known. Here we examine the Rag GTPases and the class III phosphoinositide 3-kinase (PI3K) Vps34, two mediators of amino acid signals upstream of mTOR complex 1 (mTORC1) in cell growth regulation, for their potential involvement in myogenesis. We find that, although both Rag and Vps34 mediate amino acid activation of mTORC1 in C2C12 myoblasts, they have opposing functions in myogenic differentiation. Knockdown of RagA/B enhances, whereas overexpression of active RagB/C mutants impairs, differentiation, and this inhibitory function of Rag is mediated by mTORC1 suppression of the IRS1-PI3K-Akt pathway. On the other hand, Vps34 is required for myogenic differentiation. Amino acids activate a Vps34-phospholipase D1 (PLD1) pathway that controls the production of insulin-like growth factor II, an autocrine inducer of differentiation, through the Igf2 muscle enhancer. The product of PLD, phosphatidic acid, activates the enhancer in a rapamycin-sensitive but mTOR kinase-independent manner. Our results uncover amino acid-sensing mechanisms controlling the homeostasis of myogenesis and underline the versatility and context dependence of mTOR signaling. PMID:24068326

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

    PubMed Central

    Nallar, Shreeram C.

    2014-01-01

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

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

    PubMed

    Nallar, Shreeram C; Kalvakolanu, Dhan V

    2014-08-01

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

  8. The root hair assay facilitates the use of genetic and pharmacological tools in order to dissect multiple signalling pathways that lead to programmed cell death.

    PubMed

    Kacprzyk, Joanna; Devine, Aoife; McCabe, Paul F

    2014-01-01

    The activation of programmed cell death (PCD) is often a result of complex signalling pathways whose relationship and intersection are not well understood. We recently described a PCD root hair assay and proposed that it could be used to rapidly screen genetic or pharmacological modulators of PCD. To further assess the applicability of the root hair assay for studying multiple signalling pathways leading to PCD activation we have investigated the crosstalk between salicylic acid, autophagy and apoptosis-like PCD (AL-PCD) in Arabidopsis thaliana. The root hair assay was used to determine rates of AL-PCD induced by a panel of cell death inducing treatments in wild type plants treated with chemical modulators of salicylic acid synthesis or autophagy, and in genetic lines defective in autophagy or salicylic acid signalling. The assay demonstrated that PCD induced by exogenous salicylic acid or fumonisin B1 displayed a requirement for salicylic acid signalling and was partially dependent on the salicylic acid signal transducer NPR1. Autophagy deficiency resulted in an increase in the rates of AL-PCD induced by salicylic acid and fumonisin B1, but not by gibberellic acid or abiotic stress. The phenylalanine ammonia lyase-dependent salicylic acid synthesis pathway contributed only to death induced by salicylic acid and fumonisin B1. 3-Methyladenine, which is commonly used as an inhibitor of autophagy, appeared to influence PCD induction in all treatments suggesting a possible secondary, non-autophagic, effect on a core component of the plant PCD pathway. The results suggest that salicylic acid signalling is negatively regulated by autophagy during salicylic acid and mycotoxin-induced AL-PCD. However, this crosstalk does not appear to be directly involved in PCD induced by gibberellic acid or abiotic stress. This study demonstrates that the root hair assay is an effective tool for relatively rapid investigation of complex signalling pathways leading to the activation of

  9. The Root Hair Assay Facilitates the Use of Genetic and Pharmacological Tools in Order to Dissect Multiple Signalling Pathways That Lead to Programmed Cell Death

    PubMed Central

    Kacprzyk, Joanna; Devine, Aoife; McCabe, Paul F.

    2014-01-01

    The activation of programmed cell death (PCD) is often a result of complex signalling pathways whose relationship and intersection are not well understood. We recently described a PCD root hair assay and proposed that it could be used to rapidly screen genetic or pharmacological modulators of PCD. To further assess the applicability of the root hair assay for studying multiple signalling pathways leading to PCD activation we have investigated the crosstalk between salicylic acid, autophagy and apoptosis-like PCD (AL-PCD) in Arabidopsis thaliana. The root hair assay was used to determine rates of AL-PCD induced by a panel of cell death inducing treatments in wild type plants treated with chemical modulators of salicylic acid synthesis or autophagy, and in genetic lines defective in autophagy or salicylic acid signalling. The assay demonstrated that PCD induced by exogenous salicylic acid or fumonisin B1 displayed a requirement for salicylic acid signalling and was partially dependent on the salicylic acid signal transducer NPR1. Autophagy deficiency resulted in an increase in the rates of AL-PCD induced by salicylic acid and fumonisin B1, but not by gibberellic acid or abiotic stress. The phenylalanine ammonia lyase-dependent salicylic acid synthesis pathway contributed only to death induced by salicylic acid and fumonisin B1. 3-Methyladenine, which is commonly used as an inhibitor of autophagy, appeared to influence PCD induction in all treatments suggesting a possible secondary, non-autophagic, effect on a core component of the plant PCD pathway. The results suggest that salicylic acid signalling is negatively regulated by autophagy during salicylic acid and mycotoxin-induced AL-PCD. However, this crosstalk does not appear to be directly involved in PCD induced by gibberellic acid or abiotic stress. This study demonstrates that the root hair assay is an effective tool for relatively rapid investigation of complex signalling pathways leading to the activation of

  10. Actionable pathways: interactive discovery of therapeutic targets using signaling pathway models

    PubMed Central

    Salavert, Francisco; Hidago, Marta R.; Amadoz, Alicia; Çubuk, Cankut; Medina, Ignacio; Crespo, Daniel; Carbonell-Caballero, Jose; Dopazo, Joaquín

    2016-01-01

    The discovery of actionable targets is crucial for targeted therapies and is also a constituent part of the drug discovery process. The success of an intervention over a target depends critically on its contribution, within the complex network of gene interactions, to the cellular processes responsible for disease progression or therapeutic response. Here we present PathAct, a web server that predicts the effect that interventions over genes (inhibitions or activations that simulate knock-outs, drug treatments or over-expressions) can have over signal transmission within signaling pathways and, ultimately, over the cell functionalities triggered by them. PathAct implements an advanced graphical interface that provides a unique interactive working environment in which the suitability of potentially actionable genes, that could eventually become drug targets for personalized or individualized therapies, can be easily tested. The PathAct tool can be found at: http://pathact.babelomics.org. PMID:27137885

  11. Partial Decay of Thiamine Signal Transduction Pathway Alters Growth Properties of Candida glabrata.

    PubMed

    Iosue, Christine L; Attanasio, Nicholas; Shaik, Noor F; Neal, Erin M; Leone, Sarah G; Cali, Brian J; Peel, Michael T; Grannas, Amanda M; Wykoff, Dennis D

    2016-01-01

    The phosphorylated form of thiamine (Vitamin B1), thiamine pyrophosphate (TPP) is essential for the metabolism of amino acids and carbohydrates in all organisms. Plants and microorganisms, such as yeast, synthesize thiamine de novo whereas animals do not. The thiamine signal transduction (THI) pathway in Saccharomyces cerevisiae is well characterized. The ~10 genes required for thiamine biosynthesis and uptake are transcriptionally upregulated during thiamine starvation by THI2, THI3, and PDC2. Candida glabrata, a human commensal and opportunistic pathogen, is closely related to S. cerevisiae but is missing half of the biosynthetic pathway, which limits its ability to make thiamine. We investigated the changes to the THI pathway in C. glabrata, confirming orthologous functions. We found that C. glabrata is unable to synthesize the pyrimidine subunit of thiamine as well as the thiamine precursor vitamin B6. In addition, THI2 (the gene encoding a transcription factor) is not present in C. glabrata, indicating a difference in the transcriptional regulation of the pathway. Although the pathway is upregulated by thiamine starvation in both species, C. glabrata appears to upregulate genes involved in thiamine uptake to a greater extent than S. cerevisiae. However, the altered regulation of the THI pathway does not alter the concentration of thiamine and its vitamers in the two species as measured by HPLC. Finally, we demonstrate potential consequences to having a partial decay of the THI biosynthetic and regulatory pathway. When the two species are co-cultured, the presence of thiamine allows C. glabrata to rapidly outcompete S. cerevisiae, while absence of thiamine allows S. cerevisiae to outcompete C. glabrata. This simplification of the THI pathway in C. glabrata suggests its environment provides thiamine and/or its precursors to cells, whereas S. cerevisiae is not as reliant on environmental sources of thiamine.

  12. Partial Decay of Thiamine Signal Transduction Pathway Alters Growth Properties of Candida glabrata

    PubMed Central

    Shaik, Noor F.; Neal, Erin M.; Leone, Sarah G.; Cali, Brian J.; Peel, Michael T.; Grannas, Amanda M.; Wykoff, Dennis D.

    2016-01-01

    The phosphorylated form of thiamine (Vitamin B1), thiamine pyrophosphate (TPP) is essential for the metabolism of amino acids and carbohydrates in all organisms. Plants and microorganisms, such as yeast, synthesize thiamine de novo whereas animals do not. The thiamine signal transduction (THI) pathway in Saccharomyces cerevisiae is well characterized. The ~10 genes required for thiamine biosynthesis and uptake are transcriptionally upregulated during thiamine starvation by THI2, THI3, and PDC2. Candida glabrata, a human commensal and opportunistic pathogen, is closely related to S. cerevisiae but is missing half of the biosynthetic pathway, which limits its ability to make thiamine. We investigated the changes to the THI pathway in C. glabrata, confirming orthologous functions. We found that C. glabrata is unable to synthesize the pyrimidine subunit of thiamine as well as the thiamine precursor vitamin B6. In addition, THI2 (the gene encoding a transcription factor) is not present in C. glabrata, indicating a difference in the transcriptional regulation of the pathway. Although the pathway is upregulated by thiamine starvation in both species, C. glabrata appears to upregulate genes involved in thiamine uptake to a greater extent than S. cerevisiae. However, the altered regulation of the THI pathway does not alter the concentration of thiamine and its vitamers in the two species as measured by HPLC. Finally, we demonstrate potential consequences to having a partial decay of the THI biosynthetic and regulatory pathway. When the two species are co-cultured, the presence of thiamine allows C. glabrata to rapidly outcompete S. cerevisiae, while absence of thiamine allows S. cerevisiae to outcompete C. glabrata. This simplification of the THI pathway in C. glabrata suggests its environment provides thiamine and/or its precursors to cells, whereas S. cerevisiae is not as reliant on environmental sources of thiamine. PMID:27015653

  13. Partial Decay of Thiamine Signal Transduction Pathway Alters Growth Properties of Candida glabrata.

    PubMed

    Iosue, Christine L; Attanasio, Nicholas; Shaik, Noor F; Neal, Erin M; Leone, Sarah G; Cali, Brian J; Peel, Michael T; Grannas, Amanda M; Wykoff, Dennis D

    2016-01-01

    The phosphorylated form of thiamine (Vitamin B1), thiamine pyrophosphate (TPP) is essential for the metabolism of amino acids and carbohydrates in all organisms. Plants and microorganisms, such as yeast, synthesize thiamine de novo whereas animals do not. The thiamine signal transduction (THI) pathway in Saccharomyces cerevisiae is well characterized. The ~10 genes required for thiamine biosynthesis and uptake are transcriptionally upregulated during thiamine starvation by THI2, THI3, and PDC2. Candida glabrata, a human commensal and opportunistic pathogen, is closely related to S. cerevisiae but is missing half of the biosynthetic pathway, which limits its ability to make thiamine. We investigated the changes to the THI pathway in C. glabrata, confirming orthologous functions. We found that C. glabrata is unable to synthesize the pyrimidine subunit of thiamine as well as the thiamine precursor vitamin B6. In addition, THI2 (the gene encoding a transcription factor) is not present in C. glabrata, indicating a difference in the transcriptional regulation of the pathway. Although the pathway is upregulated by thiamine starvation in both species, C. glabrata appears to upregulate genes involved in thiamine uptake to a greater extent than S. cerevisiae. However, the altered regulation of the THI pathway does not alter the concentration of thiamine and its vitamers in the two species as measured by HPLC. Finally, we demonstrate potential consequences to having a partial decay of the THI biosynthetic and regulatory pathway. When the two species are co-cultured, the presence of thiamine allows C. glabrata to rapidly outcompete S. cerevisiae, while absence of thiamine allows S. cerevisiae to outcompete C. glabrata. This simplification of the THI pathway in C. glabrata suggests its environment provides thiamine and/or its precursors to cells, whereas S. cerevisiae is not as reliant on environmental sources of thiamine. PMID:27015653

  14. Caytaxin Deficiency Disrupts Signaling Pathways in Cerebellar Cortex

    PubMed Central

    Xiao, Jianfeng; Gong, Suzhen; LeDoux, Mark S.

    2007-01-01

    The genetically dystonic (dt) rat, an autosomal recessive model of generalized dystonia, harbors an insertional mutation in Atcay. As a result, dt rats are deficient in Atcay transcript and the neuronally-restricted protein caytaxin. Previous electrophysiological and biochemical studies have defined olivocerebellar pathways, particularly the climbing fiber projection to Purkinje cells, as a site of significant functional abnormality in dt rats. In normal rats, Atcay transcript is abundantly expressed in the granular and Purkinje cell layers of cerebellar cortex. To better understand the consequences of caytaxin deficiency in cerebellar cortex, differential gene expression was examined in dt rats and their normal littermates. Data from oligonucleotide microarrays and quantitative real-time RT-PCR (QRT-PCR) identified phosphatidylinositol signaling pathways, calcium homeostasis, and extracellular matrix interactions as domains of cellular dysfunction in dt rats. In dt rats, genes encoding the corticotropin-releasing hormone receptor 1 (CRH-R1, Crhr1) and calcium-transporting plasma membrane ATPase 4 (PMCA4, Atp2b4) showed the greatest up-regulation with QRT-PCR. Immunocytochemical experiments demonstrated that CRH-R1, CRH, and PMCA4 were up-regulated in cerebellar cortex of mutant rats. Along with previous electrophysiological and pharmacological studies, our data indicate that caytaxin plays a critical role in the molecular response of Purkinje cells to climbing fiber input. Caytaxin may also contribute to maturational events in cerebellar cortex. PMID:17092653

  15. Osteocytic signalling pathways as therapeutic targets for bone fragility.

    PubMed

    Plotkin, Lilian I; Bellido, Teresita

    2016-10-01

    Osteocytes are differentiated osteoblasts that become surrounded by matrix during the process of bone formation. Acquisition of the osteocyte phenotype is achieved by profound changes in gene expression that facilitate adaptation to the changing cellular environment and constitute the molecular signature of osteocytes. During osteocytogenesis, the expression of genes that are characteristic of the osteoblast are altered and the expression of genes and/or proteins that impart dendritic cellular morphology, regulate matrix mineralization and control the function of cells at the bone surface are ordely modulated. The discovery of mutations in human osteocytic genes has contributed, in a large part, to our understanding of the role of osteocytes in bone homeostasis. Osteocytes are targets of the mechanical force imposed on the skeleton and have a critical role in integrating mechanosensory pathways with the action of hormones, which thereby leads to the orchestrated response of bone to environmental cues. Current, therapeutic approaches harness this accumulating knowledge by targeting osteocytic signalling pathways and messengers to improve skeletal health.

  16. Osteocytic signalling pathways as therapeutic targets for bone fragility.

    PubMed

    Plotkin, Lilian I; Bellido, Teresita

    2016-10-01

    Osteocytes are differentiated osteoblasts that become surrounded by matrix during the process of bone formation. Acquisition of the osteocyte phenotype is achieved by profound changes in gene expression that facilitate adaptation to the changing cellular environment and constitute the molecular signature of osteocytes. During osteocytogenesis, the expression of genes that are characteristic of the osteoblast are altered and the expression of genes and/or proteins that impart dendritic cellular morphology, regulate matrix mineralization and control the function of cells at the bone surface are ordely modulated. The discovery of mutations in human osteocytic genes has contributed, in a large part, to our understanding of the role of osteocytes in bone homeostasis. Osteocytes are targets of the mechanical force imposed on the skeleton and have a critical role in integrating mechanosensory pathways with the action of hormones, which thereby leads to the orchestrated response of bone to environmental cues. Current, therapeutic approaches harness this accumulating knowledge by targeting osteocytic signalling pathways and messengers to improve skeletal health. PMID:27230951

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

    PubMed Central

    Yuan, Wei; López Bernal, Andrés

    2007-01-01

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

  18. CREB pathway links PGE2 signaling with macrophage polarization.

    PubMed

    Luan, Bing; Yoon, Young-Sil; Le Lay, John; Kaestner, Klaus H; Hedrick, Susan; Montminy, Marc

    2015-12-22

    Obesity is thought to promote insulin resistance in part via activation of the innate immune system. Increases in proinflammatory cytokine production by M1 macrophages inhibit insulin signaling in white adipose tissue. In contrast, M2 macrophages have been found to enhance insulin sensitivity in part by reducing adipose tissue inflammation. The paracrine hormone prostaglandin E2 (PGE2) enhances M2 polarization in part through activation of the cAMP pathway, although the underlying mechanism is unclear. Here we show that PGE2 stimulates M2 polarization via the cyclic AMP-responsive element binding (CREB)-mediated induction of Krupple-like factor 4 (KLF4). Targeted disruption of CREB or the cAMP-regulated transcriptional coactivators 2 and 3 (CRTC2/3) in macrophages down-regulated M2 marker gene expression and promoted insulin resistance in the context of high-fat diet feeding. As re-expression of KLF4 rescued M2 marker gene expression in CREB-depleted cells, our results demonstrate the importance of the CREB/CRTC pathway in maintaining insulin sensitivity in white adipose tissue via its effects on the innate immune system.

  19. CREB pathway links PGE2 signaling with macrophage polarization

    PubMed Central

    Luan, Bing; Yoon, Young-Sil; Le Lay, John; Kaestner, Klaus H.; Hedrick, Susan; Montminy, Marc

    2015-01-01

    Obesity is thought to promote insulin resistance in part via activation of the innate immune system. Increases in proinflammatory cytokine production by M1 macrophages inhibit insulin signaling in white adipose tissue. In contrast, M2 macrophages have been found to enhance insulin sensitivity in part by reducing adipose tissue inflammation. The paracrine hormone prostaglandin E2 (PGE2) enhances M2 polarization in part through activation of the cAMP pathway, although the underlying mechanism is unclear. Here we show that PGE2 stimulates M2 polarization via the cyclic AMP-responsive element binding (CREB)-mediated induction of Krupple-like factor 4 (KLF4). Targeted disruption of CREB or the cAMP-regulated transcriptional coactivators 2 and 3 (CRTC2/3) in macrophages down-regulated M2 marker gene expression and promoted insulin resistance in the context of high-fat diet feeding. As re-expression of KLF4 rescued M2 marker gene expression in CREB-depleted cells, our results demonstrate the importance of the CREB/CRTC pathway in maintaining insulin sensitivity in white adipose tissue via its effects on the innate immune system. PMID:26644581

  20. Targeting cancer by binding iron: Dissecting cellular signaling pathways

    PubMed Central

    Lui, Goldie Y.L.; Kovacevic, Zaklina; Richardson, Vera; Merlot, Angelica M.; Kalinowski, Danuta S.; Richardson, Des R.

    2015-01-01

    Newer and more potent therapies are urgently needed to effectively treat advanced cancers that have developed resistance and metastasized. One such strategy is to target cancer cell iron metabolism, which is altered compared to normal cells and may facilitate their rapid proliferation. This is supported by studies reporting the anti-neoplastic activities of the clinically available iron chelators, desferrioxamine and deferasirox. More recently, ligands of the di-2-pyridylketone thiosemicarbazone (DpT) class have demonstrated potent and selective anti-proliferative activity across multiple cancer-types in vivo, fueling studies aimed at dissecting their molecular mechanisms of action. In the past five years alone, significant advances have been made in understanding how chelators not only modulate cellular iron metabolism, but also multiple signaling pathways implicated in tumor progression and metastasis. Herein, we discuss recent research on the targeting of iron in cancer cells, with a focus on the novel and potent DpT ligands. Several key studies have revealed that iron chelation can target the AKT, ERK, JNK, p38, STAT3, TGF-β, Wnt and autophagic pathways to subsequently inhibit cellular proliferation, the epithelial-mesenchymal transition (EMT) and metastasis. These developments emphasize that these novel therapies could be utilized clinically to effectively target cancer. PMID:26125440

  1. Targeting cancer by binding iron: Dissecting cellular signaling pathways.

    PubMed

    Lui, Goldie Y L; Kovacevic, Zaklina; Richardson, Vera; Merlot, Angelica M; Kalinowski, Danuta S; Richardson, Des R

    2015-08-01

    Newer and more potent therapies are urgently needed to effectively treat advanced cancers that have developed resistance and metastasized. One such strategy is to target cancer cell iron metabolism, which is altered compared to normal cells and may facilitate their rapid proliferation. This is supported by studies reporting the anti-neoplastic activities of the clinically available iron chelators, desferrioxamine and deferasirox. More recently, ligands of the di-2-pyridylketone thiosemicarbazone (DpT) class have demonstrated potent and selective anti-proliferative activity across multiple cancer-types in vivo, fueling studies aimed at dissecting their molecular mechanisms of action. In the past five years alone, significant advances have been made in understanding how chelators not only modulate cellular iron metabolism, but also multiple signaling pathways implicated in tumor progression and metastasis. Herein, we discuss recent research on the targeting of iron in cancer cells, with a focus on the novel and potent DpT ligands. Several key studies have revealed that iron chelation can target the AKT, ERK, JNK, p38, STAT3, TGF-β, Wnt and autophagic pathways to subsequently inhibit cellular proliferation, the epithelial-mesenchymal transition (EMT) and metastasis. These developments emphasize that these novel therapies could be utilized clinically to effectively target cancer. PMID:26125440

  2. mTOR signaling pathway genes in focal epilepsies.

    PubMed

    Baulac, S

    2016-01-01

    Focal epilepsies, where seizures initiate in spatially limited networks, are the most frequent epilepsy type, accounting for two-thirds of patients. Focal epilepsies have long been thought to be acquired disorders; several focal epilepsy syndromes are now proven to be (genetically heterogeneous) monogenic disorders. While earlier genetic studies have demonstrated a strong contribution of ion channel and neurotransmitter receptor genes, or synaptic secreted protein genes, later work has revealed a new class of genes encoding components of the mechanistic target of rapamycin (mTOR) signal transduction pathway. The mTOR pathway controls a myriad of biological processes among which cell growth and protein synthesis in response to several extracellular and intracellular. Recently, germline mutations have been found in genes encoding the components of the GATOR1 complex (DEPDC5, NPRL2, NPRL3), a repressor of mTORC1. These mutations are increasingly recognized as causing a wide and yet evolving spectrum of focal epilepsy syndromes, with and without cortical structural abnormalities (usually focal cortical dysplasia). Brain somatic mutations in the gene encoding mTOR (MTOR) have recently been linked to focal cortical dysplasia and other associated brain pathologies including hemimegalencephaly. This chapter reviews the genetics and neurobiology of DEPDC5, NPRL2, and NPRL3, and summarizes the clinical and molecular spectrum of GATOR1-related epilepsies. PMID:27323939

  3. Advances in mechanisms and signaling pathways of carbon nanotube toxicity.

    PubMed

    Dong, Jie; Ma, Qiang

    2015-01-01

    Carbon nanotubes (CNT) have been developed into new materials with a variety of industrial and commercial applications. In contrast, the physicochemical properties of CNT at the nanoscale render them the potency to generate toxic effects. Indeed, the potential health impacts of CNT have drawn a great deal of attention in recent years, owing to their identified toxicological and pathological consequences including cytotoxicity, inflammation, fibrosis, genotoxicity, tumorigenesis, and immunotoxicity. Understanding the mechanisms by which CNT induce toxicity and pathology is thus urgently needed for accurate risk assessment of CNT exposure in humans, and for safe and responsible development and commercialization of nanotechnology. Here, we summarize and discuss recent advances in this area with a focus on the molecular interactions between CNT and mammalian systems, and the signaling pathways important for the development of CNT toxicity such as the NF-κB, NLRP3 inflammasome, TGF-β1, MAPK, and p53 signaling cascades. With the current mechanistic evidence summarized in this review, we expect to provide new insights into CNT toxicology at the molecular level and offer new clues to the prevention of health effects resulting from CNT exposure. Moreover, we disclose questions and issues that remain in this rapidly advancing field of nanotoxicology, which would facilitate ascertaining future research directions. PMID:25676622

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

    PubMed

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

    2013-09-11

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

  5. Advances in mechanisms and signaling pathways of carbon nanotube toxicity

    PubMed Central

    Dong, Jie; Ma, Qiang

    2015-01-01

    Carbon nanotubes (CNT) have been developed into new materials with a variety of industrial and commercial applications. In contrast, the physicochemical properties of CNT at the nanoscale render them the potency to generate toxic effects. Indeed, the potential health impacts of CNT have drawn a great deal of attention in recent years, owing to their identified toxicological and pathological consequences including cytotoxicity, inflammation, fibrosis, genotoxicity, tumorigenesis, and immunotoxicity. Understanding the mechanisms by which CNT induce toxicity and pathology is thus urgently needed for accurate risk assessment of CNT exposure in humans, and for safe and responsible development and commercialization of nanotechnology. Here, we summarize and discuss recent advances in this area with a focus on the molecular interactions between CNT and mammalian systems, and the signaling pathways important for the development of CNT toxicity such as the NF-κB, NLRP3 inflammasome, TGF-β1, MAPK, and p53 signaling cascades. With the current mechanistic evidence summarized in this review, we expect to provide new insights into CNT toxicology at the molecular level and offer new clues to the prevention of health effects resulting from CNT exposure. Moreover, we disclose questions and issues that remain in this rapidly advancing field of nanotoxicology, which would facilitate ascertaining future research directions. PMID:25676622

  6. Targeting the VEGF and PDGF signaling pathway in glioblastoma treatment

    PubMed Central

    Popescu, Alisa Madalina; Alexandru, Oana; Brindusa, Corina; Purcaru, Stefana Oana; Tache, Daniela Elise; Tataranu, Ligia Gabriela; Taisescu, Citto; Dricu, Anica

    2015-01-01

    Growth factor receptors dysfunction has previously been correlated with glioma cell proliferation, ability to evade apoptosis, neo-angiogenesis and resistance to therapy. Antineoplastic molecules targeting growth factor receptors are in clinical handling, however the efficacy of these compounds has often been limited by the signaling redundancy. Here, we analyzed the effect of AG1433 (a PDGFR inhibitor), SU1498 (a VEGFR inhibitor) and BEZ235 (a PI3K/Akt/mTOR signaling pathways inhibitor) on glioblastoma cells in vitro. For this study, we used a low passage glioblastoma cell line (GB9B). Assessment of cell number over 72 h showed that the growth rate was 0.3024 and the doubling time of GB9B was 2.29 days. Similar cytotoxic effects were observed by using AG1433 and SU1498 treatment, while dual PI3K/Akt/mTOR inhibition by BEZ235 was more efficient in killing glioblastoma cells than individual PDGFR or VEGFR targeting. In SU1498 treated cells, caspase 3 activity was detected 3 hours after the treatment, while activation of caspase 8 and 9 was detected 48 hours later. AG1433 treatment induced caspase 3, 8 and 9, 3 hours after the treatment. BEZ235 treatment resulted in early caspase 3 and 8 activation, 3 hours after the treatment and an activation of caspase 9, 8 hours later. PMID:26339347

  7. Signaling pathways activated by a protease allergen in basophils

    PubMed Central

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

    2014-01-01

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

  8. Cysteine and cysteine-related signaling pathways in Arabidopsis thaliana.

    PubMed

    Romero, Luis C; Aroca, M Ángeles; Laureano-Marín, Ana M; Moreno, Inmaculada; García, Irene; Gotor, Cecilia

    2014-02-01

    Cysteine occupies a central position in plant metabolism because it is a reduced sulfur donor molecule involved in the synthesis of essential biomolecules and defense compounds. Moreover, cysteine per se and its derivative molecules play roles in the redox signaling of processes occurring in various cellular compartments. Cysteine is synthesized during the sulfate assimilation pathway via the incorporation of sulfide to O-acetylserine, catalyzed by O-acetylserine(thiol)lyase (OASTL). Plant cells contain OASTLs in the mitochondria, chloroplasts, and cytosol, resulting in a complex array of isoforms and subcellular cysteine pools. In recent years, significant progress has been made in Arabidopsis, in determining the specific roles of the OASTLs and the metabolites produced by them. Thus, the discovery of novel enzymatic activities of the less-abundant, like DES1 with L-cysteine desulfhydrase activity and SCS with S-sulfocysteine synthase activity, has provided new perspectives on their roles, besides their metabolic functions. Thereby, the research has been demonstrated that cytosolic sulfide and chloroplastic S-sulfocysteine act as signaling molecules regulating autophagy and protecting the photosystems, respectively. In the cytosol, cysteine plays an essential role in plant immunity; in the mitochondria, this molecule plays a central role in the detoxification of cyanide, which is essential for root hair development and plant responses to pathogens.

  9. Tubedown regulation of retinal endothelial permeability signaling pathways

    PubMed Central

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

    2015-01-01

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

  10. Curcumol suppresses RANKL-induced osteoclast formation by attenuating the JNK signaling pathway

    SciTech Connect

    Yu, Mingxiang; Chen, Xianying; Lv, Chaoyang; Yi, Xilu; Zhang, Yao; Xue, Mengjuan; He, Shunmei; Zhu, Guoying; Wang, Hongfu

    2014-05-02

    Highlights: • Curcumol suppresses osteoclasts differentiation in vitro. • Curcumol impairs JNK/AP-1 signaling pathway. • Curcumol may be used for treating osteoclast related diseases. - Abstract: Osteoclasts, derived from hemopoietic progenitors of the monocyte/macrophage lineage, have a unique role in bone resorption, and are considered a potential therapeutic target in the treatment of such pathologic bone diseases as osteoporosis, rheumatoid arthritis, and periodontitis. In the present study, we demonstrate that curcumol, one of the major components of the essential oil of Rhizoma Curcumae, exhibits an inhibitory effect on receptor activator of nuclear factor kappaB ligand (RANKL)-induced osteoclast differentiation with both bone marrow-derived macrophages and RAW264.7 cells in a dose-dependent manner. In addition, RANKL-induced mRNA expression of osteoclast-specific genes, such as tartrate-resistant acid phosphatase, calcitonin receptor, and cathepsin K, is prominently reduced in the presence of curcumol. Furthermore, the molecular mechanism of action was investigated, and curcumol inhibited osteoclastogenesis by specifically impairing RANKL-induced c-Jun N-terminal kinase (JNK)/activator protein-1 (AP-1) signaling, which was further identified in rescue studies by means of anisomycin, a JNK signaling-specific activator. Taken together, these findings suggest that curcumol suppresses RANKL-induced osteoclast differentiation through the JNK/AP-1 signaling pathway, and may be useful as a therapeutic treatment for bone resorption-associated diseases.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  12. Dietary pantothenic acid deficiency and excess depress the growth, intestinal mucosal immune and physical functions by regulating NF-κB, TOR, Nrf2 and MLCK signaling pathways in grass carp (Ctenopharyngodon idella).

    PubMed

    Li, Li; Feng, Lin; Jiang, Wei-Dan; Jiang, Jun; Wu, Pei; Kuang, Sheng-Yao; Tang, Ling; Tang, Wu-Neng; Zhang, Yong-An; Zhou, Xiao-Qiu; Liu, Yang

    2015-08-01

    This study investigated the effects of dietary pantothenic acid (PA) on the growth, intestinal mucosal immune and physical barrier, and relative mRNA levels of signaling molecules in the intestine of grass carp (Ctenopharyngodon idella). A total of 540 grass carp (253.44 ± 0.69 g) were fed six diets with graded levels of PA (PA1, PA15, PA30, PA45, PA60 and PA75 diets) for 8 weeks. The results indicated that compared with PA deficiency (PA1 diet) and excess (PA75 diet) groups, optimal PA supplementation increased (P < 0.05): (1) percent weight gain (PWG), feed intake and feed efficiency; (2) lysozyme activity, complement 3 content, liver-expressed antimicrobial peptide 2 and hepcidin, interleukin 10, transforming growth factor β1 and inhibitor of κBα mRNA levels in some intestinal segments; (3) activities and mRNA levels of copper/zinc superoxide dismutase, manganese superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferases and glutathione reductase, and NF-E2-related factor 2 (Nrf2) mRNA level in the whole intestine; (4) Claudin b, Claudin 3, Claudin c, Occludin and ZO-1 mRNA levels in some intestinal segments of grass carp. Conversely, optimal PA supplementation decreased (P < 0.05): (1) tumor necrosis factor α, interleukin 1β, interferon γ2, interleukin 8, nuclear factor κB P65 (NF-κB P65), IκB kinase α, IκB kinase β, IκB kinase γ and target of rapamycin (TOR) mRNA expression levels in some intestinal segments; (2) reactive oxygen species, malondialdehyde and protein carbonyl contents, and Kelch-like ECH-associating protein 1a, Kelch-like ECH-associating protein 1b in the intestine; (3) Claudin 12, Claudin 15a and myosin light-chain kinase (MLCK) mRNA levels in some intestinal segments of grass carp. In conclusion, optimum PA promoted growth, intestinal mucosal immune and physical function, as well as regulated mRNA levels of signaling molecules NF-κB P65, TOR, Nrf2 and MLCK in grass carp intestine. Based on the quadratic

  13. Bile Acids as Hormones: The FXR-FGF15/19 Pathway

    PubMed Central

    Kliewer, Steven A.; Mangelsdorf, David J.

    2015-01-01

    While it has long been recognized that bile acids are essential for solubilizing lipophilic nutrients in the small intestine, the discovery in 1999 that bile acids serve as ligands for the nuclear receptor FXR opened the floodgates in terms of characterizing their actions as selective signaling molecules. Bile acids act on FXR in ileal enterocytes to induce the expression of fibroblast growth factor (FGF) 15/19, an atypical FGF that functions as a hormone. FGF15/19 subsequently acts on a cell surface receptor complex in hepatocytes to repress bile acid synthesis and gluconeogenesis and to stimulate glycogen and protein synthesis. FGF15/19 also stimulates gallbladder filling. Thus, the bile acid-FXR-FGF15/19 signaling pathway regulates diverse aspects of the postprandial enterohepatic response. Pharmacologically, this endocrine pathway provides exciting new opportunities for treating metabolic disease and bile acid-related disorders such as primary biliary cirrhosis and bile acid diarrhea. Both FXR agonists and FGF19 analogs are currently in clinical trials. PMID:26045265

  14. Bile Acids as Hormones: The FXR-FGF15/19 Pathway.

    PubMed

    Kliewer, Steven A; Mangelsdorf, David J

    2015-01-01

    While it has long been recognized that bile acids are essential for solubilizing lipophilic nutrients in the small intestine, the discovery in 1999 that bile acids serve as ligands for the nuclear receptor farnesoid X receptor (FXR) opened the floodgates in terms of characterizing their actions as selective signaling molecules. Bile acids act on FXR in ileal enterocytes to induce the expression of fibroblast growth factor (FGF)15/19, an atypical FGF that functions as a hormone. FGF15/19 subsequently acts on a cell surface receptor complex in hepatocytes to repress bile acid synthesis and gluconeogenesis, and to stimulate glycogen and protein synthesis. FGF15/19 also stimulates gallbladder filling. Thus, the bile acid-FXR-FGF15/19 signaling pathway regulates diverse aspects of the postprandial enterohepatic response. Pharmacologically, this endocrine pathway provides exciting new opportunities for treating metabolic disease and bile acid-related disorders such as primary biliary cirrhosis and bile acid diarrhea. Both FXR agonists and FGF19 analogs are currently in clinical trials. PMID:26045265

  15. Nutritional Signaling via Free Fatty Acid Receptors.

    PubMed

    Miyamoto, Junki; Hasegawa, Sae; Kasubuchi, Mayu; Ichimura, Atsuhiko; Nakajima, Akira; Kimura, Ikuo

    2016-01-01

    Excess energy is stored primarily as triglycerides, which are mobilized when demand for energy arises. Dysfunc