Sample records for factor signaling maintains

  1. Control circuit maintains unity power factor of reactive load

    NASA Technical Reports Server (NTRS)

    Kramer, M.; Martinage, L. H.

    1966-01-01

    Circuit including feedback control elements automatically corrects the power factor of a reactive load. It maintains power supply efficiency where negative load reactance changes and varies by providing corrective error signals to the control windings of a power supply transformer.

  2. The C. elegans embryonic fate specification factor EGL-18 (GATA) is reutilized downstream of Wnt signaling to maintain a population of larval progenitor cells.

    PubMed

    Gorrepati, Lakshmi; Eisenmann, David M

    2015-01-01

    In metazoans, stem cells in developing and adult tissues can divide asymmetrically to give rise to a daughter that differentiates and a daughter that retains the progenitor fate. Although the short-lived nematode C. elegans does not possess adult somatic stem cells, the lateral hypodermal seam cells behave in a similar manner: they divide once per larval stage to generate an anterior daughter that adopts a non-dividing differentiated fate and a posterior daughter that retains the seam fate and the ability to divide further. Wnt signaling pathway is known to regulate the asymmetry of these divisions and maintain the progenitor cell fate in one daughter, but how activation of the Wnt pathway accomplished this was unknown. We describe here our recent work that identified the GATA transcription factor EGL-18 as a downstream target of Wnt signaling necessary for maintenance of a progenitor population of larval seam cells. EGL-18 was previously shown to act in the initial specification of the seam cells in the embryo. Thus the acquisition of a Wnt-responsive cis-regulatory module allows an embryonic fate specification factor to be reutilized later in life downstream of a different regulator (Wnt signaling) to maintain a progenitor cell population. These results support the use of seam cell development in C. elegans as a simple model system for studying stem and progenitor cell biology.

  3. IFN-γ signaling maintains skin pigmentation homeostasis through regulation of melanosome maturation

    PubMed Central

    Natarajan, Vivek T.; Ganju, Parul; Singh, Archana; Vijayan, Vinaya; Kirty, Kritika; Yadav, Shalini; Puntambekar, Shraddha; Bajaj, Sonali; Dani, Prachi P.; Kar, Hemanta K.; Gadgil, Chetan J.; Natarajan, Krishnamurthy; Rani, Rajni; Gokhale, Rajesh S.

    2014-01-01

    Cellular homeostasis is an outcome of complex interacting processes with nonlinear feedbacks that can span distinct spatial and temporal dimensions. Skin tanning is one such dynamic response that maintains genome integrity of epidermal cells. Although pathways underlying hyperpigmentation cascade are recognized, negative feedback regulatory loops that can dampen the activated melanogenesis process are not completely understood. In this study, we delineate a regulatory role of IFN-γ in skin pigmentation biology. We show that IFN-γ signaling impedes maturation of the key organelle melanosome by concerted regulation of several pigmentation genes. Withdrawal of IFN-γ signal spontaneously restores normal cellular programming. This effect in melanocytes is mediated by IFN regulatory factor-1 and is not dependent on the central regulator microphthalmia-associated transcription factor. Chronic IFN-γ signaling shows a clear hypopigmentation phenotype in both mouse and human skin. Interestingly, IFN-γ KO mice display a delayed recovery response to restore basal state of epidermal pigmentation after UV-induced tanning. Together, our studies delineate a new spatiotemporal role of the IFN-γ signaling network in skin pigmentation homeostasis, which could have implications in various cutaneous depigmentary and malignant disorders. PMID:24474804

  4. Involvement of extracellular factors in maintaining self-renewal of neural stem cell by nestin.

    PubMed

    Di, Chun Guang; Xiang, Andy Peng; Jia, Lei; Liu, Jun Feng; Lahn, Bruce T; Ma, Bao Feng

    2014-07-09

    Nestin knockout leads to embryonic lethality and self-renewal deficiency in neural stem cells (NSCs). However, how nestin maintains self-renewal remains uncertain. Here, we used the dosage effect of nestin in heterozygous mice (Nes+/-) to study self-renewal of NSCs. With existing extracellular signaling in vivo or in vitro, nestin levels do not affect proliferation ability or apoptosis when compared between Nes+/- and Nes+/+ NSCs. However, self-renewal ability of Nes+/- NSCs is impaired when plated at a low cell density and completely lost at a clonal density. This deficiency in self-renewal at a clonal density is rescued using a medium conditioned by Nes+/+ NSCs. In addition, the Akt signaling pathway is altered at low density and reversed by conditioned medium. Our data show that secreted factors contribute toward maintaining self-renewal of NSCs by nestin, potentially through Akt signaling.

  5. Hormonal pleiotropy helps maintain queen signal honesty in a highly eusocial wasp

    USDA-ARS?s Scientific Manuscript database

    In insect societies, both queens and workers produce chemicals that reliably signal caste membership and reproductive status. The mechanisms that help to maintain the honesty of such queen and fertility signals, however, remain poorly studied. Here we test if queen signal honesty could be based on t...

  6. TIF-IA-dependent regulation of ribosome synthesis in drosophila muscle is required to maintain systemic insulin signaling and larval growth.

    PubMed

    Ghosh, Abhishek; Rideout, Elizabeth J; Grewal, Savraj S

    2014-10-01

    The conserved TOR kinase signaling network links nutrient availability to cell, tissue and body growth in animals. One important growth-regulatory target of TOR signaling is ribosome biogenesis. Studies in yeast and mammalian cell culture have described how TOR controls rRNA synthesis-a limiting step in ribosome biogenesis-via the RNA Polymerase I transcription factor TIF-IA. However, the contribution of TOR-dependent ribosome synthesis to tissue and body growth in animals is less clear. Here we show in Drosophila larvae that ribosome synthesis in muscle is required non-autonomously to maintain normal body growth and development. We find that amino acid starvation and TOR inhibition lead to reduced levels of TIF-IA, and decreased rRNA synthesis in larval muscle. When we mimic this decrease in muscle ribosome synthesis using RNAi-mediated knockdown of TIF-IA, we observe delayed larval development and reduced body growth. This reduction in growth is caused by lowered systemic insulin signaling via two endocrine responses: reduced expression of Drosophila insulin-like peptides (dILPs) from the brain and increased expression of Imp-L2-a secreted factor that binds and inhibits dILP activity-from muscle. We also observed that maintaining TIF-IA levels in muscle could partially reverse the starvation-mediated suppression of systemic insulin signaling. Finally, we show that activation of TOR specifically in muscle can increase overall body size and this effect requires TIF-IA function. These data suggest that muscle ribosome synthesis functions as a nutrient-dependent checkpoint for overall body growth: in nutrient rich conditions, TOR is required to maintain levels of TIF-IA and ribosome synthesis to promote high levels of systemic insulin, but under conditions of starvation stress, reduced muscle ribosome synthesis triggers an endocrine response that limits systemic insulin signaling to restrict growth and maintain homeostasis.

  7. TIF-IA-Dependent Regulation of Ribosome Synthesis in Drosophila Muscle Is Required to Maintain Systemic Insulin Signaling and Larval Growth

    PubMed Central

    Ghosh, Abhishek; Rideout, Elizabeth J.; Grewal, Savraj S.

    2014-01-01

    The conserved TOR kinase signaling network links nutrient availability to cell, tissue and body growth in animals. One important growth-regulatory target of TOR signaling is ribosome biogenesis. Studies in yeast and mammalian cell culture have described how TOR controls rRNA synthesis—a limiting step in ribosome biogenesis—via the RNA Polymerase I transcription factor TIF-IA. However, the contribution of TOR-dependent ribosome synthesis to tissue and body growth in animals is less clear. Here we show in Drosophila larvae that ribosome synthesis in muscle is required non-autonomously to maintain normal body growth and development. We find that amino acid starvation and TOR inhibition lead to reduced levels of TIF-IA, and decreased rRNA synthesis in larval muscle. When we mimic this decrease in muscle ribosome synthesis using RNAi-mediated knockdown of TIF-IA, we observe delayed larval development and reduced body growth. This reduction in growth is caused by lowered systemic insulin signaling via two endocrine responses: reduced expression of Drosophila insulin-like peptides (dILPs) from the brain and increased expression of Imp-L2—a secreted factor that binds and inhibits dILP activity—from muscle. We also observed that maintaining TIF-IA levels in muscle could partially reverse the starvation-mediated suppression of systemic insulin signaling. Finally, we show that activation of TOR specifically in muscle can increase overall body size and this effect requires TIF-IA function. These data suggest that muscle ribosome synthesis functions as a nutrient-dependent checkpoint for overall body growth: in nutrient rich conditions, TOR is required to maintain levels of TIF-IA and ribosome synthesis to promote high levels of systemic insulin, but under conditions of starvation stress, reduced muscle ribosome synthesis triggers an endocrine response that limits systemic insulin signaling to restrict growth and maintain homeostasis. PMID:25356674

  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. Wnt signaling-mediated redox regulation maintains the germ line stem cell differentiation niche

    PubMed Central

    Wang, Su; Gao, Yuan; Song, Xiaoqing; Ma, Xing; Zhu, Xiujuan; Mao, Ying; Yang, Zhihao; Ni, Jianquan; Li, Hua; Malanowski, Kathryn E; Anoja, Perera; Park, Jungeun; Haug, Jeff; Xie, Ting

    2015-01-01

    Adult stem cells continuously undergo self-renewal and generate differentiated cells. In the Drosophila ovary, two separate niches control germ line stem cell (GSC) self-renewal and differentiation processes. Compared to the self-renewing niche, relatively little is known about the maintenance and function of the differentiation niche. In this study, we show that the cellular redox state regulated by Wnt signaling is critical for the maintenance and function of the differentiation niche to promote GSC progeny differentiation. Defective Wnt signaling causes the loss of the differentiation niche and the upregulated BMP signaling in differentiated GSC progeny, thereby disrupting germ cell differentiation. Mechanistically, Wnt signaling controls the expression of multiple glutathione-S-transferase family genes and the cellular redox state. Finally, Wnt2 and Wnt4 function redundantly to maintain active Wnt signaling in the differentiation niche. Therefore, this study has revealed a novel strategy for Wnt signaling in regulating the cellular redox state and maintaining the differentiation niche. DOI: http://dx.doi.org/10.7554/eLife.08174.001 PMID:26452202

  10. C. elegans GATA factors EGL-18 and ELT-6 function downstream of Wnt signaling to maintain the progenitor fate during larval asymmetric divisions of the seam cells.

    PubMed

    Gorrepati, Lakshmi; Thompson, Kenneth W; Eisenmann, David M

    2013-05-01

    The C. elegans seam cells are lateral epithelial cells arrayed in a single line from anterior to posterior that divide in an asymmetric, stem cell-like manner during larval development. These asymmetric divisions are regulated by Wnt signaling; in most divisions, the posterior daughter in which the Wnt pathway is activated maintains the progenitor seam fate, while the anterior daughter in which the Wnt pathway is not activated adopts a differentiated hypodermal fate. Using mRNA tagging and microarray analysis, we identified the functionally redundant GATA factor genes egl-18 and elt-6 as Wnt pathway targets in the larval seam cells. EGL-18 and ELT-6 have previously been shown to be required for initial seam cell specification in the embryo. We show that in larval seam cell asymmetric divisions, EGL-18 is expressed strongly in the posterior seam-fated daughter. egl-18 and elt-6 are necessary for larval seam cell specification, and for hypodermal to seam cell fate transformations induced by ectopic Wnt pathway overactivation. The TCF homolog POP-1 binds a site in the egl-18 promoter in vitro, and this site is necessary for robust seam cell expression in vivo. Finally, larval overexpression of EGL-18 is sufficient to drive expression of a seam marker in other hypodermal cells in wild-type animals, and in anterior hypodermal-fated daughters in a Wnt pathway-sensitized background. These data suggest that two GATA factors that are required for seam cell specification in the embryo independently of Wnt signaling are reused downstream of Wnt signaling to maintain the progenitor fate during stem cell-like divisions in larval development.

  11. C. elegans GATA factors EGL-18 and ELT-6 function downstream of Wnt signaling to maintain the progenitor fate during larval asymmetric divisions of the seam cells

    PubMed Central

    Gorrepati, Lakshmi; Thompson, Kenneth W.; Eisenmann, David M.

    2013-01-01

    The C. elegans seam cells are lateral epithelial cells arrayed in a single line from anterior to posterior that divide in an asymmetric, stem cell-like manner during larval development. These asymmetric divisions are regulated by Wnt signaling; in most divisions, the posterior daughter in which the Wnt pathway is activated maintains the progenitor seam fate, while the anterior daughter in which the Wnt pathway is not activated adopts a differentiated hypodermal fate. Using mRNA tagging and microarray analysis, we identified the functionally redundant GATA factor genes egl-18 and elt-6 as Wnt pathway targets in the larval seam cells. EGL-18 and ELT-6 have previously been shown to be required for initial seam cell specification in the embryo. We show that in larval seam cell asymmetric divisions, EGL-18 is expressed strongly in the posterior seam-fated daughter. egl-18 and elt-6 are necessary for larval seam cell specification, and for hypodermal to seam cell fate transformations induced by ectopic Wnt pathway overactivation. The TCF homolog POP-1 binds a site in the egl-18 promoter in vitro, and this site is necessary for robust seam cell expression in vivo. Finally, larval overexpression of EGL-18 is sufficient to drive expression of a seam marker in other hypodermal cells in wild-type animals, and in anterior hypodermal-fated daughters in a Wnt pathway-sensitized background. These data suggest that two GATA factors that are required for seam cell specification in the embryo independently of Wnt signaling are reused downstream of Wnt signaling to maintain the progenitor fate during stem cell-like divisions in larval development. PMID:23633508

  12. The Fibroblast Growth Factor signaling pathway.

    PubMed

    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. For further resources related to this article, please visit the WIREs website. © 2015 The Authors. WIREs Developmental Biology published by Wiley Periodicals, Inc.

  13. Hepatocyte growth factor/scatter factor-MET signaling in neural crest-derived melanocyte development.

    PubMed

    Kos, L; Aronzon, A; Takayama, H; Maina, F; Ponzetto, C; Merlino, G; Pavan, W

    1999-02-01

    The mechanisms governing development of neural crest-derived melanocytes, and how alterations in these pathways lead to hypopigmentation disorders, are not completely understood. Hepatocyte growth factor/scatter factor (HGF/SF) signaling through the tyrosine-kinase receptor, MET, is capable of promoting the proliferation, increasing the motility, and maintaining high tyrosinase activity and melanin synthesis of melanocytes in vitro. In addition, transgenic mice that ubiquitously overexpress HGF/SF demonstrate hyperpigmentation in the skin and leptomenigenes and develop melanomas. To investigate whether HGF/ SF-MET signaling is involved in the development of neural crest-derived melanocytes, transgenic embryos, ubiquitously overexpressing HGF/SF, were analyzed. In HGF/SF transgenic embryos, the distribution of melanoblasts along the characteristic migratory pathway was not affected. However, additional ectopically localized melanoblasts were also observed in the dorsal root ganglia and neural tube, as early as 11.5 days post coitus (p.c.). We utilized an in vitro neural crest culture assay to further explore the role of HGF/SF-MET signaling in neural crest development. HGF/SF added to neural crest cultures increased melanoblast number, permitted differentiation into pigmented melanocytes, promoted melanoblast survival, and could replace mast-cell growth factor/Steel factor (MGF) in explant cultures. To examine whether HGF/SF-MET signaling is required for the proper development of melanocytes, embryos with a targeted Met null mutation (Met-/-) were analysed. In Met-/- embryos, melanoblast number and location were not overtly affected up to 14 days p.c. These results demonstrate that HGF/SF-MET signaling influences, but is not required for, the initial development of neural crest-derived melanocytes in vivo and in vitro.

  14. The role of predators in maintaining the geographic organization of aposematic signals.

    PubMed

    Chouteau, Mathieu; Angers, Bernard

    2011-12-01

    Selective predation of aposematic signals is expected to promote phenotypic uniformity. But while these signals may be uniform within a population, numerous species display impressive variations in warning signals among adjacent populations. Predators from different localities who learn to avoid distinct signals while performing intense selection on others are thus expected to maintain such a geographic organization. We tested this assumption by placing clay frog models, representing distinct color morphs of the Peruvian poison dart frog Ranitomeya imitator and a nonconspicuous frog, reciprocally between adjacent localities. In each locality, avian predators were able to discriminate between warning signals; the adjacent exotic morph experienced up to four times more attacks than the local one and two times more than the nonconspicuous phenotype. Moreover, predation attempts on the exotic morph quickly decreased to almost nil, suggesting rapid learning. This experiment offers direct evidence for the existence of different predator communities performing localized homogenizing selection on distinct aposematic signals.

  15. Notch Signaling Regulates Late-Stage Epidermal Differentiation and Maintains Postnatal Hair Cycle Homeostasis

    PubMed Central

    Lin, Hsien-Yi; Kao, Cheng-Heng; Lin, Kurt Ming-Chao; Kaartinen, Vesa; Yang, Liang-Tung

    2011-01-01

    Background Notch signaling involves ligand-receptor interactions through direct cell-cell contact. Multiple Notch receptors and ligands are expressed in the epidermis and hair follicles during embryonic development and the adult stage. Although Notch signaling plays an important role in regulating differentiation of the epidermis and hair follicles, it remains unclear how Notch signaling participates in late-stage epidermal differentiation and postnatal hair cycle homeostasis. Methodology and Principal Findings We applied Cre/loxP system to generate conditional gene targeted mice that allow inactivation of critical components of Notch signaling pathway in the skin. Rbpj, the core component of all four Notch receptors, and Pofut1, an essential factor for ligand-receptor interactions, were inactivated in hair follicle lineages and suprabasal layer of the epidermis using the Tgfb3-Cre mouse line. Rbpj conditional inactivation resulted in granular parakeratosis and reactive epidermal hyperplasia. Pofut1 conditional inactivation led to ultrastructural abnormalities in the granular layer and altered filaggrin processing in the epidermis, suggesting a perturbation of the granular layer differentiation. Disruption of Pofut1 in hair follicle lineages resulted in aberrant telogen morphology, a decrease of bulge stem cell markers, and a concomitant increase of K14-positive keratinocytes in the isthmus of mutant hair follicles. Pofut1-deficent hair follicles displayed a delay in anagen re-entry and dysregulation of proliferation and apoptosis during the hair cycle transition. Moreover, increased DNA double stand breaks were detected in Pofut1-deficent hair follicles, and real time PCR analyses on bulge keratinocytes isolated by FACS revealed an induction of DNA damage response and a paucity of DNA repair machinery in mutant bulge keratinocytes. Significance our data reveal a role for Notch signaling in regulating late-stage epidermal differentiation. Notch signaling is

  16. NANOS2 acts downstream of glial cell line-derived neurotrophic factor signaling to suppress differentiation of spermatogonial stem cells.

    PubMed

    Sada, Aiko; Hasegawa, Kazuteru; Pin, Pui Han; Saga, Yumiko

    2012-02-01

    Stem cells are maintained by both stem cell-extrinsic niche signals and stem cell-intrinsic factors. During murine spermatogenesis, glial cell line-derived neurotrophic factor (GDNF) signal emanated from Sertoli cells and germ cell-intrinsic factor NANOS2 represent key regulators for the maintenance of spermatogonial stem cells. However, it remains unclear how these factors intersect in stem cells to control their cellular state. Here, we show that GDNF signaling is essential to maintain NANOS2 expression, and overexpression of Nanos2 can alleviate the stem cell loss phenotype caused by the depletion of Gfra1, a receptor for GDNF. By using an inducible Cre-loxP system, we show that NANOS2 expression is downregulated upon the conditional knockout (cKO) of Gfra1, while ectopic expression of Nanos2 in GFRA1-negative spermatogonia does not induce de novo GFRA1 expression. Furthermore, overexpression of Nanos2 in the Gfra1-cKO testes prevents precocious differentiation of the Gfra1-knockout stem cells and partially rescues the stem cell loss phenotypes of Gfra1-deficient mice, indicating that the stem cell differentiation can be suppressed by NANOS2 even in the absence of GDNF signaling. Taken together, we suggest that NANOS2 acts downstream of GDNF signaling to maintain undifferentiated state of spermatogonial stem cells. Copyright © 2011 AlphaMed Press.

  17. Endothelial β-Catenin Signaling Is Required for Maintaining Adult Blood-Brain Barrier Integrity and CNS Homeostasis

    PubMed Central

    Tran, Khiem A.; Zhang, Xianming; Predescu, Dan; Huang, Xiaojia; Machado, Roberto F.; Göthert, Joachim R.; Malik, Asrar B.; Valyi-Nagy, Tibor; Zhao, You-Yang

    2015-01-01

    Background The blood-brain barrier (BBB) formed by brain endothelial cells (ECs) interconnected by tight junctions (TJs) is essential for the homeostasis of the central nervous system (CNS). Although studies have shown the importance of various signaling molecules in BBB formation during development, little is known about the molecular basis regulating the integrity of the adult BBB. Methods and Results Using a mouse model with tamoxifen-inducible EC-restricted disruption of ctnnb1 (iCKO), here we show that endothelial β-catenin signaling is essential for maintaining BBB integrity and CNS homeostasis in adult. The iCKO mice developed severe seizures accompanied by neuronal injury, multiple brain petechial hemorrhages, and CNS inflammation, and all died postictal. Disruption of endothelial β-catenin induced BBB breakdown and downregulation of specific TJ proteins Claudin-1 and -3 in adult brain ECs. The clinical relevance of the data is indicated by the observation of decreased expression of Claudin-1 and nuclear β-catenin in brain ECs of hemorrhagic lesions of hemorrhagic stroke patients. Conclusion These results demonstrate the prerequisite role of endothelial β-catenin in maintaining the integrity of adult BBB. The results suggest that BBB dysfunction secondary to defective β-catenin transcription activity is a key pathogenic factor in hemorrhagic stroke, seizure activity and CNS inflammation. PMID:26538583

  18. Effects of Signaled Positive Reinforcement on Problem Behavior Maintained by Negative Reinforcement

    ERIC Educational Resources Information Center

    Schieltz, Kelly M.; Wacker, David P.; Romani, Patrick W.

    2017-01-01

    We evaluated the effects of providing positive reinforcement for task completion, signaled via the presence of a tangible item, on escape-maintained problem behavior displayed by three typically developing children during one-time 90-min outpatient evaluations. Brief functional analyses of problem behavior, conducted within a multielement design,…

  19. Type I insulin-like growth factor receptor signaling in hematological malignancies

    PubMed Central

    Vishwamitra, Deeksha; George, Suraj Konnath; Shi, Ping; Kaseb, Ahmed O.; Amin, Hesham M.

    2017-01-01

    The insulin-like growth factor (IGF) signaling system plays key roles in the establishment and progression of different types of cancer. In agreement with this idea, substantial evidence has shown that the type I IGF receptor (IGF-IR) and its primary ligand IGF-I are important for maintaining the survival of malignant cells of hematopoietic origin. In this review, we discuss current understanding of the role of IGF-IR signaling in cancer with a focus on the hematological neoplasms. We also address the emergence of IGF-IR as a potential therapeutic target for the treatment of different types of cancer including plasma cell myeloma, leukemia, and lymphoma. PMID:27661006

  20. [Factors influencing the sense of unintegration of thoughts in maintaining anger].

    PubMed

    Endo, Hiroko; Yukawa, Shintaro

    2013-12-01

    Endo and Yukawa (2012) investigated the process of maintaining anger and demonstrated that a sense of unintegration of thoughts maintained anger by promoting recurrent thinking and avoidance behavior. Our present study examined how personality characteristics and situational factors affected the process of maintaining anger. Undergraduates (N=713) wrote about an anger episode, and completed questionnaires assessing their sense of unintegration of thoughts, recurrent thinking, avoidance behaviors, and maintaining anger. The questionnaires also assessed personality characteristics such as difficulty in identifying feelings, and situational factors such as the need for maintaining relationships, anger arousability, and meaning-making for the anger episode. The results of covariance structure analysis indicated that difficulties in identifying feelings and anger arousability contributed to maintaining anger by increasing the sense of unintegration of thoughts just after the episode. However, the need for maintaining relationships directly reduced the sense of unintegration of thoughts just after the episode, and indirectly decreased the present sense of unintegration of thoughts by meaning-making. Moreover, although recurrent thinking promoted the current sense of unintegration of thoughts, it also provided meaning.

  1. Wnt signaling maintains the notochord fate for progenitor cells and supports the posterior extension of the notochord.

    PubMed

    Ukita, Kanako; Hirahara, Shino; Oshima, Naoko; Imuta, Yu; Yoshimoto, Aki; Jang, Chuan-Wei; Oginuma, Masayuki; Saga, Yumiko; Behringer, Richard R; Kondoh, Hisato; Sasaki, Hiroshi

    2009-10-01

    The notochord develops from notochord progenitor cells (NPCs) and functions as a major signaling center to regulate trunk and tail development. NPCs are initially specified in the node by Wnt and Nodal signals at the gastrula stage. However, the underlying mechanism that maintains the NPCs throughout embryogenesis to contribute to the posterior extension of the notochord remains unclear. Here, we demonstrate that Wnt signaling in the NPCs is essential for posterior extension of the notochord. Genetic labeling revealed that the Noto-expressing cells in the ventral node contribute the NPCs that reside in the tail bud. Robust Wnt signaling in the NPCs was observed during posterior notochord extension. Genetic attenuation of the Wnt signal via notochord-specific beta-catenin gene ablation resulted in posterior truncation of the notochord. In the NPCs of such mutant embryos, the expression of notochord-specific genes was down-regulated, and an endodermal marker, E-cadherin, was observed. No significant alteration of cell proliferation or apoptosis of the NPCs was detected. Taken together, our data indicate that the NPCs are derived from Noto-positive node cells, and are not fully committed to a notochordal fate. Sustained Wnt signaling is required to maintain the NPCs' notochordal fate.

  2. Endothelial β-Catenin Signaling Is Required for Maintaining Adult Blood-Brain Barrier Integrity and Central Nervous System Homeostasis.

    PubMed

    Tran, Khiem A; Zhang, Xianming; Predescu, Dan; Huang, Xiaojia; Machado, Roberto F; Göthert, Joachim R; Malik, Asrar B; Valyi-Nagy, Tibor; Zhao, You-Yang

    2016-01-12

    The blood-brain barrier (BBB) formed by brain endothelial cells interconnected by tight junctions is essential for the homeostasis of the central nervous system. Although studies have shown the importance of various signaling molecules in BBB formation during development, little is known about the molecular basis regulating the integrity of the adult BBB. Using a mouse model with tamoxifen-inducible endothelial cell-restricted disruption of ctnnb1 (iCKO), we show here that endothelial β-catenin signaling is essential for maintaining BBB integrity and central nervous system homeostasis in adult mice. The iCKO mice developed severe seizures accompanied by neuronal injury, multiple brain petechial hemorrhages, and central nervous system inflammation, and all had postictal death. Disruption of endothelial β-catenin induced BBB breakdown and downregulation of the specific tight junction proteins claudin-1 and -3 in adult brain endothelial cells. The clinical relevance of the data is indicated by the observation of decreased expression of claudin-1 and nuclear β-catenin in brain endothelial cells of hemorrhagic lesions of hemorrhagic stroke patients. These results demonstrate the prerequisite role of endothelial β-catenin in maintaining the integrity of adult BBB. The results suggest that BBB dysfunction secondary to defective β-catenin transcription activity is a key pathogenic factor in hemorrhagic stroke, seizure activity, and central nervous system inflammation. © 2015 American Heart Association, Inc.

  3. Reduced insulin signaling maintains electrical transmission in a neural circuit in aging flies

    PubMed Central

    McGourty, Kieran; Allen, Marcus J.; Madem, Sirisha Kudumala; Adcott, Jennifer; Kerr, Fiona; Wong, Chi Tung; Vincent, Alec; Godenschwege, Tanja; Boucrot, Emmanuel; Partridge, Linda

    2017-01-01

    Lowered insulin/insulin-like growth factor (IGF) signaling (IIS) can extend healthy lifespan in worms, flies, and mice, but it can also have adverse effects (the “insulin paradox”). Chronic, moderately lowered IIS rescues age-related decline in neurotransmission through the Drosophila giant fiber system (GFS), a simple escape response neuronal circuit, by increasing targeting of the gap junctional protein innexin shaking-B to gap junctions (GJs). Endosomal recycling of GJs was also stimulated in cultured human cells when IIS was reduced. Furthermore, increasing the activity of the recycling small guanosine triphosphatases (GTPases) Rab4 or Rab11 was sufficient to maintain GJs upon elevated IIS in cultured human cells and in flies, and to rescue age-related loss of GJs and of GFS function. Lowered IIS thus elevates endosomal recycling of GJs in neurons and other cell types, pointing to a cellular mechanism for therapeutic intervention into aging-related neuronal disorders. PMID:28902870

  4. Molecular Mechanisms of Fibroblast Growth Factor Signaling in Physiology and Pathology

    PubMed Central

    Belov, Artur A.; Mohammadi, Moosa

    2013-01-01

    Fibroblast growth factors (FGFs) signal in a paracrine or endocrine fashion to mediate a myriad of biological activities, ranging from issuing developmental cues, maintaining tissue homeostasis, and regulating metabolic processes. FGFs carry out their diverse functions by binding and dimerizing FGF receptors (FGFRs) in a heparan sulfate (HS) cofactor- or Klotho coreceptor-assisted manner. The accumulated wealth of structural and biophysical data in the past decade has transformed our understanding of the mechanism of FGF signaling in human health and development, and has provided novel concepts in receptor tyrosine kinase (RTK) signaling. Among these contributions are the elucidation of HS-assisted receptor dimerization, delineation of the molecular determinants of ligand–receptor specificity, tyrosine kinase regulation, receptor cis-autoinhibition, and tyrosine trans-autophosphorylation. These structural studies have also revealed how disease-associated mutations highjack the physiological mechanisms of FGFR regulation to contribute to human diseases. In this paper, we will discuss the structurally and biophysically derived mechanisms of FGF signaling, and how the insights gained may guide the development of therapies for treatment of a diverse array of human diseases. PMID:23732477

  5. Molecular mechanisms of fibroblast growth factor signaling in physiology and pathology.

    PubMed

    Belov, Artur A; Mohammadi, Moosa

    2013-06-01

    Fibroblast growth factors (FGFs) signal in a paracrine or endocrine fashion to mediate a myriad of biological activities, ranging from issuing developmental cues, maintaining tissue homeostasis, and regulating metabolic processes. FGFs carry out their diverse functions by binding and dimerizing FGF receptors (FGFRs) in a heparan sulfate (HS) cofactor- or Klotho coreceptor-assisted manner. The accumulated wealth of structural and biophysical data in the past decade has transformed our understanding of the mechanism of FGF signaling in human health and development, and has provided novel concepts in receptor tyrosine kinase (RTK) signaling. Among these contributions are the elucidation of HS-assisted receptor dimerization, delineation of the molecular determinants of ligand-receptor specificity, tyrosine kinase regulation, receptor cis-autoinhibition, and tyrosine trans-autophosphorylation. These structural studies have also revealed how disease-associated mutations highjack the physiological mechanisms of FGFR regulation to contribute to human diseases. In this paper, we will discuss the structurally and biophysically derived mechanisms of FGF signaling, and how the insights gained may guide the development of therapies for treatment of a diverse array of human diseases.

  6. Redox-regulated growth factor survival signaling.

    PubMed

    Woolley, John F; Corcoran, Aoife; Groeger, Gillian; Landry, William D; Cotter, Thomas G

    2013-11-20

    Once the thought of as unwanted byproducts of cellular respiration in eukaryotes, reactive oxygen species (ROS) have been shown to facilitate essential physiological roles. It is now understood that ROS are critical mediators of intracellular signaling. Control of signal transduction downstream of growth factor receptors by ROS is a complex process whose details are only recently coming to light. Indeed, recent evidence points to control of signal propagation by ROS at multiple levels in the typical cascade. Growth factor stimulation activates nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Noxs) at the membrane, producing superoxide in the extracellular matrix, which is catalyzed to the membrane-permeable hydrogen peroxide (H2O2) that mediates intracellular signaling events. The potential for H2O2, however, to disrupt cellular functions by damaging proteins and nucleic acids demands that its levels are kept in check by receptor-associated peroxiredoxins. This interplay of Nox and peroxiredoxin activity moderates levels of H2O2 sufficiently to modify signaling partners locally. Among the best studied of these partners are redox-controlled phosphatases that are inactivated by H2O2. Phosphatases regulate signal propagation downstream of receptors, and thus their inactivation allows a further level of control. Transmission of information further downstream to targets such as transcription factors, themselves regulated by ROS, completes this pathway. Thus, signal propagation or attenuation can be dictated by ROS at multiple points. Given the complex nature of these processes, we envisage the emerging trends in the field of redox signaling in the context of growth factor stimulation.

  7. Three WRKY transcription factors additively repress abscisic acid and gibberellin signaling in aleurone cells.

    PubMed

    Zhang, Liyuan; Gu, Lingkun; Ringler, Patricia; Smith, Stanley; Rushton, Paul J; Shen, Qingxi J

    2015-07-01

    Members of the WRKY transcription factor superfamily are essential for the regulation of many plant pathways. Functional redundancy due to duplications of WRKY transcription factors, however, complicates genetic analysis by allowing single-mutant plants to maintain wild-type phenotypes. Our analyses indicate that three group I WRKY genes, OsWRKY24, -53, and -70, act in a partially redundant manner. All three showed characteristics of typical WRKY transcription factors: each localized to nuclei and yeast one-hybrid assays indicated that they all bind to W-boxes, including those present in their own promoters. Quantitative real time-PCR (qRT-PCR) analyses indicated that the expression levels of the three WRKY genes varied in the different tissues tested. Particle bombardment-mediated transient expression analyses indicated that all three genes repress the GA and ABA signaling in a dosage-dependent manner. Combination of all three WRKY genes showed additive antagonism of ABA and GA signaling. These results suggest that these WRKY proteins function as negative transcriptional regulators of GA and ABA signaling. However, different combinations of these WRKY genes can lead to varied strengths in suppression of their targets. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. Primary cilia maintain corneal epithelial homeostasis by regulation of the Notch signaling pathway

    PubMed Central

    Grisanti, Laura; Revenkova, Ekaterina; Gordon, Ronald E.

    2016-01-01

    Primary cilia have been linked to signaling pathways involved in cell proliferation, cell motility and cell polarity. Defects in ciliary function result in developmental abnormalities and multiple ciliopathies. Patients affected by severe ciliopathies, such as Meckel syndrome, present several ocular surface disease conditions of unclear pathogenesis. Here, we show that primary cilia are predominantly present on basal cells of the mouse corneal epithelium (CE) throughout development and in the adult. Conditional ablation of cilia in the CE leads to an increase in proliferation and vertical migration of basal corneal epithelial cells (CECs). A consequent increase in cell density of suprabasal layers results in a thicker than normal CE. Surprisingly, in cilia-deficient CE, cilia-mediated signaling pathways, including Hh and Wnt pathways, were not affected but the intensity of Notch signaling was severely diminished. Although Notch1 and Notch2 receptors were expressed normally, nuclear Notch1 intracellular domain (N1ICD) expression was severely reduced. Postnatal development analysis revealed that in cilia-deficient CECs downregulation of the Notch pathway precedes cell proliferation defects. Thus, we have uncovered a function of the primary cilium in maintaining homeostasis of the CE by balancing proliferation and vertical migration of basal CECs through modulation of Notch signaling. PMID:27122169

  9. GIV/Girdin Links Vascular Endothelial Growth Factor Signaling to Akt Survival Signaling in Podocytes Independent of Nephrin

    PubMed Central

    Wang, Honghui; Misaki, Taro; Taupin, Vanessa; Eguchi, Akiko; Ghosh, Pradipta

    2015-01-01

    Podocytes are critically involved in the maintenance of the glomerular filtration barrier and are key targets of injury in many glomerular diseases. Chronic injury leads to progressive loss of podocytes, glomerulosclerosis, and renal failure. Thus, it is essential to maintain podocyte survival and avoid apoptosis after acute glomerular injury. In normal glomeruli, podocyte survival is mediated via nephrin-dependent Akt signaling. In several glomerular diseases, nephrin expression decreases and podocyte survival correlates with increased vascular endothelial growth factor (VEGF) signaling. How VEGF signaling contributes to podocyte survival and prevents apoptosis remains unknown. We show here that Gα–interacting, vesicle-associated protein (GIV)/girdin mediates VEGF receptor 2 (VEGFR2) signaling and compensates for nephrin loss. In puromycin aminonucleoside nephrosis (PAN), GIV expression increased, GIV was phosphorylated by VEGFR2, and p-GIV bound and activated Gαi3 and enhanced downstream Akt2, mammalian target of rapamycin complex 1 (mTORC1), and mammalian target of rapamycin complex-2 (mTORC2) signaling. In GIV-depleted podocytes, VEGF-induced Akt activation was abolished, apoptosis was triggered, and cell migration was impaired. These effects were reversed by introducing GIV but not a GIV mutant that cannot activate Gαi3. Our data indicate that after PAN injury, VEGF promotes podocyte survival by triggering assembly of an activated VEGFR2/GIV/Gαi3 signaling complex and enhancing downstream PI3K/Akt survival signaling. Because of its important role in promoting podocyte survival, GIV may represent a novel target for therapeutic intervention in the nephrotic syndrome and other proteinuric diseases. PMID:25012178

  10. The statistical mechanics of complex signaling networks: nerve growth factor signaling

    NASA Astrophysics Data System (ADS)

    Brown, K. S.; Hill, C. C.; Calero, G. A.; Myers, C. R.; Lee, K. H.; Sethna, J. P.; Cerione, R. A.

    2004-10-01

    The inherent complexity of cellular signaling networks and their importance to a wide range of cellular functions necessitates the development of modeling methods that can be applied toward making predictions and highlighting the appropriate experiments to test our understanding of how these systems are designed and function. We use methods of statistical mechanics to extract useful predictions for complex cellular signaling networks. A key difficulty with signaling models is that, while significant effort is being made to experimentally measure the rate constants for individual steps in these networks, many of the parameters required to describe their behavior remain unknown or at best represent estimates. To establish the usefulness of our approach, we have applied our methods toward modeling the nerve growth factor (NGF)-induced differentiation of neuronal cells. In particular, we study the actions of NGF and mitogenic epidermal growth factor (EGF) in rat pheochromocytoma (PC12) cells. Through a network of intermediate signaling proteins, each of these growth factors stimulates extracellular regulated kinase (Erk) phosphorylation with distinct dynamical profiles. Using our modeling approach, we are able to predict the influence of specific signaling modules in determining the integrated cellular response to the two growth factors. Our methods also raise some interesting insights into the design and possible evolution of cellular systems, highlighting an inherent property of these systems that we call 'sloppiness.'

  11. Pioneer factors, genetic competence, and inductive signaling: programming liver and pancreas progenitors from the endoderm.

    PubMed

    Zaret, K S; Watts, J; Xu, J; Wandzioch, E; Smale, S T; Sekiya, T

    2008-01-01

    The endoderm is a multipotent progenitor cell population in the embryo that gives rise to the liver, pancreas, and other cell types and provides paradigms for understanding cell-type specification. Studies of isolated embryo tissue cells and genetic approaches in vivo have defined fibroblast growth factor/mitogen-activated protein kinase (FGF/MAPK) and bone morphogenetic protein (BMP) signaling pathways that induce liver and pancreatic fates in the endoderm. In undifferentiated endoderm cells, the FoxA and GATA transcription factors are among the first to engage silent genes, helping to endow competence for cell-type specification. FoxA proteins can bind their target sites in highly compacted chromatin and open up the local region for other factors to bind; hence, they have been termed "pioneer factors." We recently found that FoxA proteins remain bound to chromatin in mitosis, as an epigenetic mark. In embryonic stem cells, which lack FoxA, FoxA target sites can be occupied by FoxD3, which in turn helps to maintain a local demethylation of chromatin. By these means, a cascade of Fox factors helps to endow progenitor cells with the competence to activate genes in response to tissue-inductive signals. Understanding such epigenetic mechanisms for transcriptional competence coupled with knowledge of the relevant signals for cell-type specification should greatly facilitate efforts to predictably differentiate stem cells to liver and pancreatic fates.

  12. RAD18 Activates the G2/M Checkpoint through DNA Damage Signaling to Maintain Genome Integrity after Ionizing Radiation Exposure

    PubMed Central

    Sasatani, Megumi; Xu, Yanbin; Kawai, Hidehiko; Cao, Lili; Tateishi, Satoshi; Shimura, Tsutomu; Li, Jianxiang; Iizuka, Daisuke; Noda, Asao; Hamasaki, Kanya; Kusunoki, Yoichiro; Kamiya, Kenji

    2015-01-01

    The ubiquitin ligase RAD18 is involved in post replication repair pathways via its recruitment to stalled replication forks, and its role in the ubiquitylation of proliferating cell nuclear antigen (PCNA). Recently, it has been reported that RAD18 is also recruited to DNA double strand break (DSB) sites, where it plays novel functions in the DNA damage response induced by ionizing radiation (IR). This new role is independent of PCNA ubiquitylation, but little is known about how RAD18 functions after IR exposure. Here, we describe a role for RAD18 in the IR-induced DNA damage signaling pathway at G2/M phase in the cell cycle. Depleting cells of RAD18 reduced the recruitment of the DNA damage signaling factors ATM, γH2AX, and 53BP1 to foci in cells at the G2/M phase after IR exposure, and attenuated activation of the G2/M checkpoint. Furthermore, depletion of RAD18 increased micronuclei formation and cell death following IR exposure, both in vitro and in vivo. Our data suggest that RAD18 can function as a mediator for DNA damage response signals to activate the G2/M checkpoint in order to maintain genome integrity and cell survival after IR exposure. PMID:25675240

  13. Moving beyond the illness: factors contributing to gaining and maintaining employment.

    PubMed

    Cunningham, K; Wolbert, R; Brockmeier, M B

    2000-08-01

    The work presented here, exploratory in nature, uses a comparative and qualitative approach to understand the factors associated with the ability of individuals with severe and persistent mental illness to successfully gain and maintain employment. Based on open-ended interviews with individuals in an Assertive Community Treatment (ACT) program, we compare the experiences of those who have been successful gaining and maintaining employment, with those who have been successful gaining but not maintaining work, and those who have been unsuccessful gaining employment. The three groups seemed to differ in three significant ways: (1) in the ways the individuals talked about their illness, (2) in the ways the individuals talked about work, and (3) in the strategies they described for coping with bad days. In each of these areas individuals' awareness of and attitude toward their illness was significant. The findings have clear implications for agencies working to help people with severe and persistent mental illness obtain and maintain employment.

  14. Unravelling signal escape through maintained EGFR activation in advanced non-small cell lung cancer (NSCLC): new treatment options

    PubMed Central

    Remon, Jordi; Besse, Benjamin

    2016-01-01

    The discovery of activating epidermal growth factor receptor (EGFR) mutations has opened up a new era in the development of more effective treatments for patients with non-small cell lung cancer (NSCLC). However, patients with EGFR-activating mutated NSCLC treated with EGFR tyrosine kinase inhibitors (TKIs) ultimately develop acquired resistance (AR). Among known cases of patients with AR, 70% of the mechanisms involved in the development of AR to EGFR TKI have been identified and may be categorised as either secondary EGFR mutations such as the T790M mutation, activation of bypass track signalling pathways such as MET amplification, or histologic transformation. EGFR-mutant NSCLC tumours maintain oncogenic addiction to the EGFR pathway beyond progression with EGFR TKI. Clinical strategies that can be implemented in daily clinical practice to potentially overcome this resistance and prolong the outcome in this subgroup of patients are presented. PMID:27843631

  15. Fibroblast growth factor receptor signaling crosstalk in skeletogenesis.

    PubMed

    Miraoui, Hichem; Marie, Pierre J

    2010-11-02

    Fibroblast growth factors (FGFs) play important roles in the control of embryonic and postnatal skeletal development by activating signaling through FGF receptors (FGFRs). Germline gain-of-function mutations in FGFR constitutively activate FGFR signaling, causing chondrocyte and osteoblast dysfunctions that result in skeletal dysplasias. Crosstalk between the FGFR pathway and other signaling cascades controls skeletal precursor cell differentiation. Genetic analyses revealed that the interplay of WNT and FGFR1 determines the fate and differentiation of mesenchymal stem cells during mouse craniofacial skeletogenesis. Additionally, interactions between FGFR signaling and other receptor tyrosine kinase networks, such as those mediated by the epidermal growth factor receptor and platelet-derived growth factor receptor α, were associated with excessive osteoblast differentiation and bone formation in the human skeletal dysplasia called craniosynostosis, which is a disorder of skull development. We review the roles of FGFR signaling and its crosstalk with other pathways in controlling skeletal cell fate and discuss how this crosstalk could be pharmacologically targeted to correct the abnormal cell phenotype in skeletal dysplasias caused by aberrant FGFR signaling.

  16. A critical role for transcription factor Smad4 in T cell function independent of transforming growth factor beta receptor signaling

    PubMed Central

    Gu, Ai-Di; Zhang, Song; Wang, Yunqi; Xiong, Hui; Curtis, Thomas A.; Wan, Yisong Y.

    2014-01-01

    Summary Transforming growth factor-beta (TGF-β) suppresses T cell function to maintain self-tolerance and to promote tumor immune evasion. Yet how Smad4, a transcription factor component of TGF-β signaling, regulates T cell function remains unclear. Here we have demonstrated an essential role for Smad4 in promoting T cell function during autoimmunity and anti-tumor immunity. Smad4 deletion rescued the lethal autoimmunity resulting from transforming growth factor-beta receptor (TGF-βR) deletion and compromised T-cell-mediated tumor rejection. While Smad4 was dispensable for T cell generation, homeostasis and effector function, it was essential for T cell proliferation following activation in vitro and in vivo. The transcription factor Myc was identified to mediate Smad4-controlled T cell proliferation. This study thus reveals a requirement of Smad4 for T-cell-mediated autoimmunity and tumor rejection, which is beyond the current paradigm. It highlights a TGF-βR-independent role for Smad4 in promoting T cell function, autoimmunity and anti-tumor immunity. PMID:25577439

  17. Insulin-Like Growth Factors Are Expressed in the Taste System, but Do Not Maintain Adult Taste Buds.

    PubMed

    Biggs, Bradley T; Tang, Tao; Krimm, Robin F

    2016-01-01

    Growth factors regulate cell growth and differentiation in many tissues. In the taste system, as yet unknown growth factors are produced by neurons to maintain taste buds. A number of growth factor receptors are expressed at greater levels in taste buds than in the surrounding epithelium and may be receptors for candidate factors involved in taste bud maintenance. We determined that the ligands of eight of these receptors were expressed in the E14.5 geniculate ganglion and that four of these ligands were expressed in the adult geniculate ganglion. Of these, the insulin-like growth factors (IGF1, IGF2) were expressed in the ganglion and their receptor, insulin-like growth factor receptor 1 (IGF1R), were expressed at the highest levels in taste buds. To determine whether IGF1R regulates taste bud number or structure, we conditionally eliminated IGF1R from the lingual epithelium of mice using the keratin 14 (K14) promoter (K14-Cre::Igf1rlox/lox). While K14-Cre::Igf1rlox/lox mice had significantly fewer taste buds at P30 compared with control mice (Igf1rlox/lox), this difference was not observed by P80. IGF1R removal did not affect taste bud size or cell number, and the number of phospholipase C β2- (PLCβ2) and carbonic anhydrase 4- (Car4) positive taste receptor cells did not differ between genotypes. Taste buds at the back of the tongue fungiform taste field were larger and contained more cells than those at the tongue tip, and these differences were diminished in K14-Cre::Igf1rlox/lox mice. The epithelium was thicker at the back versus the tip of the tongue, and this difference was also attenuated in K14-Cre::Igf1rlox/lox mice. We conclude that, although IGFs are expressed at high levels in the taste system, they likely play little or no role in maintaining adult taste bud structure. IGFs have a potential role in establishing the initial number of taste buds, and there may be limits on epithelial thickness in the absence of IGF1R signaling.

  18. Insulin-Like Growth Factors Are Expressed in the Taste System, but Do Not Maintain Adult Taste Buds

    PubMed Central

    Biggs, Bradley T.; Tang, Tao; Krimm, Robin F.

    2016-01-01

    Growth factors regulate cell growth and differentiation in many tissues. In the taste system, as yet unknown growth factors are produced by neurons to maintain taste buds. A number of growth factor receptors are expressed at greater levels in taste buds than in the surrounding epithelium and may be receptors for candidate factors involved in taste bud maintenance. We determined that the ligands of eight of these receptors were expressed in the E14.5 geniculate ganglion and that four of these ligands were expressed in the adult geniculate ganglion. Of these, the insulin-like growth factors (IGF1, IGF2) were expressed in the ganglion and their receptor, insulin-like growth factor receptor 1 (IGF1R), were expressed at the highest levels in taste buds. To determine whether IGF1R regulates taste bud number or structure, we conditionally eliminated IGF1R from the lingual epithelium of mice using the keratin 14 (K14) promoter (K14-Cre::Igf1rlox/lox). While K14-Cre::Igf1rlox/lox mice had significantly fewer taste buds at P30 compared with control mice (Igf1rlox/lox), this difference was not observed by P80. IGF1R removal did not affect taste bud size or cell number, and the number of phospholipase C β2- (PLCβ2) and carbonic anhydrase 4- (Car4) positive taste receptor cells did not differ between genotypes. Taste buds at the back of the tongue fungiform taste field were larger and contained more cells than those at the tongue tip, and these differences were diminished in K14-Cre::Igf1rlox/lox mice. The epithelium was thicker at the back versus the tip of the tongue, and this difference was also attenuated in K14-Cre::Igf1rlox/lox mice. We conclude that, although IGFs are expressed at high levels in the taste system, they likely play little or no role in maintaining adult taste bud structure. IGFs have a potential role in establishing the initial number of taste buds, and there may be limits on epithelial thickness in the absence of IGF1R signaling. PMID:26901525

  19. Bidirectional juxtacrine ephrinB2/Ephs signaling promotes angiogenesis of ECs and maintains self-renewal of MSCs.

    PubMed

    Cao, Cen; Huang, Ying; Tang, Qingming; Zhang, Chenguang; Shi, Lei; Zhao, Jiajia; Hu, Li; Hu, Zhewen; Liu, Yun; Chen, Lili

    2018-07-01

    Co-transplantation of endothelial cells (ECs) and mesenchymal stem cells (MSCs) is an important strategy for repairing complex and large bone defects. However, the ways in which ECs and MSCs interact remain to be fully clarified. We found that forward ephrinB2/Ephs signaling from hBMSCs to hUVECs promoted the tube formation of hUVECs by activating the PI3K/AKT/mTOR pathway. Reverse ephrinB2/Ephs signaling from hUVECs to hBMSCs promoted the proliferation and maintenance of hBMSCs self-renewal via upregulation of OCT4, SOX2, and YAP1. Subcutaneous co-transplantation of ECs and MSCs in nude mice confirmed that forward ephrinB2/Ephs signaling could increase the cross-sectional area of blood vessels in the transplanted area, and reverse ephrinB2/Ephs signaling could maintain the self-renewal of transplanted hBMSCs in vivo. Based on these results, ephrinB2/Ephs bidirectional juxtacrine regulation between ECs and MSCs plays a pivotal role in improving the healing of bone defects by promoting angiogenesis and achieving a sufficient number of MSCs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. NFκB–Pim-1–Eomesodermin axis is critical for maintaining CD8 T-cell memory quality

    PubMed Central

    Knudson, Karin M.; Saxena, Vikas; Altman, Amnon; Daniels, Mark A.; Teixeiro, Emma

    2017-01-01

    T-cell memory is critical for long-term immunity. However, the factors involved in maintaining the persistence, function, and phenotype of the memory pool are undefined. Eomesodermin (Eomes) is required for the establishment of the memory pool. Here, we show that in T cells transitioning to memory, the expression of high levels of Eomes is not constitutive but rather requires a continuum of cell-intrinsic NFκB signaling. Failure to maintain NFκB signals after the peak of the response led to impaired Eomes expression and a defect in the maintenance of CD8 T-cell memory. Strikingly, we found that antigen receptor [T-cell receptor (TCR)] signaling regulates this process through expression of the NFκB-dependent kinase proviral integration site for Moloney murine leukemia virus-1 (PIM-1), which in turn regulates NFκB and Eomes. T cells defective in TCR-dependent NFκB signaling were impaired in late expression of Pim-1, Eomes, and CD8 memory. These defects were rescued when TCR-dependent NFκB signaling was restored. We also found that NFκB–Pim-1 signals were required at memory to maintain memory CD8 T-cell longevity, effector function, and Eomes expression. Hence, an NFκB–Pim-1–Eomes axis regulates Eomes levels to maintain memory fitness. PMID:28193872

  1. Increased avidity for Dpp/BMP2 maintains the proliferation of progenitors-like cells in the Drosophila eye.

    PubMed

    Neto, Marta; Aguilar-Hidalgo, Daniel; Casares, Fernando

    2016-10-01

    During organ development, the progenitor state is transient, and depends on specific combinations of transcription factors and extracellular signals. Not surprisingly, abnormal maintenance of progenitor transcription factors may lead to tissue overgrowth, and the concurrence of signals from the local environment is often critical to trigger this overgrowth. Therefore, identifying specific combinations of transcription factors/signals promoting -or opposing- proliferation in progenitors is essential to understand normal development and disease. We have investigated this issue using the Drosophila eye as model. Transcription factors hth and tsh are transiently expressed in eye progenitors causing the expansion of the progenitor pool. However, if their co-expression is maintained experimentally, cell proliferation continues and differentiation is halted. Here we show that Hth+Tsh-induced tissue overgrowth requires the BMP2 Dpp and the abnormal hyperactivation of its pathway. Rather than using autocrine Dpp expression, Hth+Tsh cells increase their avidity for Dpp, produced locally, by upregulating extracellular matrix components. During normal development, Dpp represses hth and tsh ensuring that the progenitor state is transient. However, cells in which Hth+Tsh expression is forcibly maintained use Dpp to enhance their proliferation. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Tongue and Taste Organ Biology and Function: Homeostasis Maintained by Hedgehog Signaling.

    PubMed

    Mistretta, Charlotte M; Kumari, Archana

    2017-02-10

    The tongue is an elaborate complex of heterogeneous tissues with taste organs of diverse embryonic origins. The lingual taste organs are papillae, composed of an epithelium that includes specialized taste buds, the basal lamina, and a lamina propria core with matrix molecules, fibroblasts, nerves, and vessels. Because taste organs are dynamic in cell biology and sensory function, homeostasis requires tight regulation in specific compartments or niches. Recently, the Hedgehog (Hh) pathway has emerged as an essential regulator that maintains lingual taste papillae, taste bud and progenitor cell proliferation and differentiation, and neurophysiological function. Activating or suppressing Hh signaling, with genetic models or pharmacological agents used in cancer treatments, disrupts taste papilla and taste bud integrity and can eliminate responses from taste nerves to chemical stimuli but not to touch or temperature. Understanding Hh regulation of taste organ homeostasis contributes knowledge about the basic biology underlying taste disruptions in patients treated with Hh pathway inhibitors.

  3. Physiological Notch Signaling Maintains Bone Homeostasis via RBPjk and Hey Upstream of NFATc1

    PubMed Central

    Tu, Xiaolin; Chen, Jianquan; Lim, Joohyun; Karner, Courtney M.; Lee, Seung-Yon; Heisig, Julia; Wiese, Cornelia; Surendran, Kameswaran; Kopan, Raphael; Gessler, Manfred; Long, Fanxin

    2012-01-01

    Notch signaling between neighboring cells controls many cell fate decisions in metazoans both during embryogenesis and in postnatal life. Previously, we uncovered a critical role for physiological Notch signaling in suppressing osteoblast differentiation in vivo. However, the contribution of individual Notch receptors and the downstream signaling mechanism have not been elucidated. Here we report that removal of Notch2, but not Notch1, from the embryonic limb mesenchyme markedly increased trabecular bone mass in adolescent mice. Deletion of the transcription factor RBPjk, a mediator of all canonical Notch signaling, in the mesenchymal progenitors but not the more mature osteoblast-lineage cells, caused a dramatic high-bone-mass phenotype characterized by increased osteoblast numbers, diminished bone marrow mesenchymal progenitor pool, and rapid age-dependent bone loss. Moreover, mice deficient in Hey1 and HeyL, two target genes of Notch-RBPjk signaling, exhibited high bone mass. Interestingly, Hey1 bound to and suppressed the NFATc1 promoter, and RBPjk deletion increased NFATc1 expression in bone. Finally, pharmacological inhibition of NFAT alleviated the high-bone-mass phenotype caused by RBPjk deletion. Thus, Notch-RBPjk signaling functions in part through Hey1-mediated inhibition of NFATc1 to suppress osteoblastogenesis, contributing to bone homeostasis in vivo. PMID:22457635

  4. Anti-apoptotic Role of Caspase-cleaved GAB1 Adaptor Protein in Hepatocyte Growth Factor/Scatter Factor-MET Receptor Protein Signaling*

    PubMed Central

    Le Goff, Arnaud; Ji, Zongling; Leclercq, Bérénice; Bourette, Roland P.; Mougel, Alexandra; Guerardel, Cateline; de Launoit, Yvan; Vicogne, Jérôme; Goormachtigh, Gautier; Fafeur, Véronique

    2012-01-01

    The GRB2-associated binder 1 (GAB1) docking/scaffold protein is a key mediator of the MET-tyrosine kinase receptor activated by hepatocyte growth factor/scatter factor (HGF/SF). Activated MET promotes recruitment and tyrosine phosphorylation of GAB1, which in turn recruits multiple proteins and mediates MET signaling leading to cell survival, motility, and morphogenesis. We previously reported that, without its ligand, MET is a functional caspase target during apoptosis, allowing the generation of a p40-MET fragment that amplifies apoptosis. In this study we established that GAB1 is also a functional caspase target by evidencing a caspase-cleaved p35-GAB1 fragment that contains the MET binding domain. GAB1 is cleaved by caspases before MET, and the resulting p35-GAB1 fragment is phosphorylated by MET upon HGF/SF binding and can interact with a subset of GAB1 partners, PI3K, and GRB2 but not with SHP2. This p35-GAB1 fragment favors cell survival by maintaining HGF/SF-induced MET activation of AKT and by hindering p40-MET pro-apoptotic function. These data demonstrate an anti-apoptotic role of caspase-cleaved GAB1 in HGF/SF-MET signaling. PMID:22915589

  5. Novel synthetic monoketone transmute radiation-triggered NFκB-dependent TNFα cross-signaling feedback maintained NFκB and favors neuroblastoma regression.

    PubMed

    Aravindan, Sheeja; Natarajan, Mohan; Awasthi, Vibhudutta; Herman, Terence S; Aravindan, Natarajan

    2013-01-01

    Recently, we demonstrated that radiation (IR) instigates the occurrence of a NFκB-TNFα feedback cycle which sustains persistent NFκB activation in neuroblastoma (NB) cells and favors survival advantage and clonal expansion. Further, we reported that curcumin targets IR-induced survival signaling and NFκB dependent hTERT mediated clonal expansion in human NB cells. Herein, we investigated the efficacy of a novel synthetic monoketone, EF24, a curcumin analog in inhibiting persistent NFκB activation by disrupting the IR-induced NFκB-TNFα-NFκB feedback signaling in NB and subsequent mitigation of survival advantage and clonal expansion. EF24 profoundly suppressed the IR-induced NFκB-DNA binding activity/promoter activation and, maintained the NFκB repression by deterring NFκB-dependent TNFα transactivation/intercellular secretion in genetically varied human NB (SH-SY5Y, IMR-32, SK-PN-DW, MC-IXC and SK-N-MC) cell types. Further, EF24 completely suppressed IR-induced NFκB-TNFα cross-signaling dependent transactivation/translation of pro-survival IAP1, IAP2 and Survivin and subsequent cell survival. In corroboration, EF24 treatment maximally blocked IR-induced NFκB dependent hTERT transactivation/promoter activation, telomerase activation and consequent clonal expansion. EF24 displayed significant regulation of IR-induced feedback dependent NFκB and NFκB mediated survival signaling and complete regression of NB xenograft. Together, the results demonstrate for the first time that, novel synthetic monoketone EF24 potentiates radiotherapy and mitigates NB progression by selectively targeting IR-triggered NFκB-dependent TNFα-NFκB cross-signaling maintained NFκB mediated survival advantage and clonal expansion.

  6. Novel Synthetic Monoketone Transmute Radiation-Triggered NFκB-Dependent TNFα Cross-Signaling Feedback Maintained NFκB and Favors Neuroblastoma Regression

    PubMed Central

    Aravindan, Sheeja; Natarajan, Mohan; Awasthi, Vibhudutta; Herman, Terence S.; Aravindan, Natarajan

    2013-01-01

    Recently, we demonstrated that radiation (IR) instigates the occurrence of a NFκB-TNFα feedback cycle which sustains persistent NFκB activation in neuroblastoma (NB) cells and favors survival advantage and clonal expansion. Further, we reported that curcumin targets IR-induced survival signaling and NFκB dependent hTERT mediated clonal expansion in human NB cells. Herein, we investigated the efficacy of a novel synthetic monoketone, EF24, a curcumin analog in inhibiting persistent NFκB activation by disrupting the IR-induced NFκB-TNFα-NFκB feedback signaling in NB and subsequent mitigation of survival advantage and clonal expansion. EF24 profoundly suppressed the IR-induced NFκB-DNA binding activity/promoter activation and, maintained the NFκB repression by deterring NFκB-dependent TNFα transactivation/intercellular secretion in genetically varied human NB (SH-SY5Y, IMR-32, SK–PN–DW, MC-IXC and SK–N-MC) cell types. Further, EF24 completely suppressed IR-induced NFκB-TNFα cross-signaling dependent transactivation/translation of pro-survival IAP1, IAP2 and Survivin and subsequent cell survival. In corroboration, EF24 treatment maximally blocked IR-induced NFκB dependent hTERT transactivation/promoter activation, telomerase activation and consequent clonal expansion. EF24 displayed significant regulation of IR-induced feedback dependent NFκB and NFκB mediated survival signaling and complete regression of NB xenograft. Together, the results demonstrate for the first time that, novel synthetic monoketone EF24 potentiates radiotherapy and mitigates NB progression by selectively targeting IR-triggered NFκB-dependent TNFα-NFκB cross-signaling maintained NFκB mediated survival advantage and clonal expansion. PMID:23967300

  7. Human Cytomegalovirus Strategies to Maintain and Promote mRNA Translation

    PubMed Central

    Vincent, Heather A.; Ziehr, Benjamin; Moorman, Nathaniel J.

    2016-01-01

    mRNA translation requires the ordered assembly of translation initiation factors and ribosomal subunits on a transcript. Host signaling pathways regulate each step in this process to match levels of protein synthesis to environmental cues. In response to infection, cells activate multiple defenses that limit viral protein synthesis, which viruses must counteract to successfully replicate. Human cytomegalovirus (HCMV) inhibits host defenses that limit viral protein expression and manipulates host signaling pathways to promote the expression of both host and viral proteins necessary for virus replication. Here we review key regulatory steps in mRNA translation, and the strategies used by HCMV to maintain protein synthesis in infected cells. PMID:27089357

  8. Cell Identity Switching Regulated by Retinoic Acid Signaling Maintains Homogeneous Segments in the Hindbrain.

    PubMed

    Addison, Megan; Xu, Qiling; Cayuso, Jordi; Wilkinson, David G

    2018-06-04

    The patterning of tissues to form subdivisions with distinct and homogeneous regional identity is potentially disrupted by cell intermingling. Transplantation studies suggest that homogeneous segmental identity in the hindbrain is maintained by identity switching of cells that intermingle into another segment. We show that switching occurs during normal development and is mediated by feedback between segment identity and the retinoic acid degrading enzymes, cyp26b1 and cyp26c1. egr2, which specifies the segmental identity of rhombomeres r3 and r5, underlies the lower expression level of cyp26b1 and cyp26c1 in r3 and r5 compared with r2, r4, and r6. Consequently, r3 or r5 cells that intermingle into adjacent segments encounter cells with higher cyp26b1/c1 expression, which we find is required for downregulation of egr2b expression. Furthermore, egr2b expression is regulated in r2, r4, and r6 by non-autonomous mechanisms that depend upon the number of neighbors that express egr2b. These findings reveal that a community regulation of retinoid signaling maintains homogeneous segmental identity. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

  9. Quantification of growth factor signaling and pathway cross talk by live-cell imaging

    PubMed Central

    Gross, Sean M.

    2017-01-01

    Peptide growth factors stimulate cellular responses through activation of their transmembrane receptors. Multiple intracellular signaling cascades are engaged following growth factor–receptor binding, leading to short- and long-term biological effects. Each receptor-activated signaling pathway does not act in isolation but rather interacts at different levels with other pathways to shape signaling networks that are distinctive for each growth factor. To gain insights into the specifics of growth factor-regulated interactions among different signaling cascades, we developed a HeLa cell line stably expressing fluorescent live-cell imaging reporters that are readouts for two major growth factor-stimulated pathways, Ras–Raf–Mek–ERK and phosphatidylinositol (PI) 3-kinase–Akt. Incubation of cells with epidermal growth factor (EGF) resulted in rapid, robust, and sustained ERK signaling but shorter-term activation of Akt. In contrast, hepatocyte growth factor induced sustained Akt signaling but weak and short-lived ERK activity, and insulin-like growth factor-I stimulated strong long-term Akt responses but negligible ERK signaling. To address potential interactions between signaling pathways, we employed specific small-molecule inhibitors. In cells incubated with EGF or platelet-derived growth factor-AA, Raf activation and the subsequent stimulation of ERK reduced Akt signaling, whereas Mek inhibition, which blocked ERK activation, enhanced Akt and turned transient effects into sustained responses. Our results reveal that individual growth factors initiate signaling cascades that vary markedly in strength and duration and demonstrate in living cells the dramatic effects of cross talk from Raf and Mek to PI 3-kinase and Akt. Our data further indicate how specific growth factors can encode distinct cellular behaviors by promoting complex interactions among signaling pathways. PMID:28100485

  10. Quantification of growth factor signaling and pathway cross talk by live-cell imaging.

    PubMed

    Gross, Sean M; Rotwein, Peter

    2017-03-01

    Peptide growth factors stimulate cellular responses through activation of their transmembrane receptors. Multiple intracellular signaling cascades are engaged following growth factor-receptor binding, leading to short- and long-term biological effects. Each receptor-activated signaling pathway does not act in isolation but rather interacts at different levels with other pathways to shape signaling networks that are distinctive for each growth factor. To gain insights into the specifics of growth factor-regulated interactions among different signaling cascades, we developed a HeLa cell line stably expressing fluorescent live-cell imaging reporters that are readouts for two major growth factor-stimulated pathways, Ras-Raf-Mek-ERK and phosphatidylinositol (PI) 3-kinase-Akt. Incubation of cells with epidermal growth factor (EGF) resulted in rapid, robust, and sustained ERK signaling but shorter-term activation of Akt. In contrast, hepatocyte growth factor induced sustained Akt signaling but weak and short-lived ERK activity, and insulin-like growth factor-I stimulated strong long-term Akt responses but negligible ERK signaling. To address potential interactions between signaling pathways, we employed specific small-molecule inhibitors. In cells incubated with EGF or platelet-derived growth factor-AA, Raf activation and the subsequent stimulation of ERK reduced Akt signaling, whereas Mek inhibition, which blocked ERK activation, enhanced Akt and turned transient effects into sustained responses. Our results reveal that individual growth factors initiate signaling cascades that vary markedly in strength and duration and demonstrate in living cells the dramatic effects of cross talk from Raf and Mek to PI 3-kinase and Akt. Our data further indicate how specific growth factors can encode distinct cellular behaviors by promoting complex interactions among signaling pathways. Copyright © 2017 the American Physiological Society.

  11. ABCB5 maintains melanoma-initiating cells through a pro-inflammatory cytokine signaling circuit

    PubMed Central

    Wilson, Brian J.; Saab, Karim R.; Ma, Jie; Schatton, Tobias; Pütz, Pablo; Zhan, Qian; Murphy, George F.; Gasser, Martin; Waaga-Gasser, Ana Maria; Frank, Natasha Y.; Frank, Markus H.

    2014-01-01

    The drug efflux transporter ABCB5 identifies cancer stem-like cells (CSC) in diverse human malignancies, where its expression is associated with clinical disease progression and tumor recurrence. ABCB5 confers therapeutic resistance but other functions in tumorigenesis independent of drug efflux have not been described that might help explain why it is so broadly overexpressed in human cancer. Here we show that in melanoma-initiating cells ABCB5 controls IL-1β secretion which serves to maintain slow-cycling, chemoresistant cells through an IL-1β/IL8/CXCR1 cytokine signaling circuit. This CSC maintenance circuit involved reciprocal paracrine interactions with ABCB5-negative cancer cell populations. ABCB5 blockade induced cellular differentiation, reversed resistance to multiple chemotherapeutic agents, and impaired tumor growth in vivo. Together, our results defined a novel function for ABCB5 in CSC maintenance and tumor growth. PMID:24934811

  12. Factors Associated with Young Children's Opportunities for Maintaining Family Relationships during Maternal Incarceration

    ERIC Educational Resources Information Center

    Poehlmann, Julie; Shlafer, Rebecca J.; Maes, Elizabeth; Hanneman, Ashley

    2008-01-01

    Children affected by maternal incarceration experience challenges maintaining continuous family relationships because of changes in caregivers, separation from siblings, and limited contact with mothers. In this mixed-method study, we investigated maternal and contextual factors associated with continuity in family relationships of children living…

  13. Eph/Ephrin signalling maintains eye field segregation from adjacent neural plate territories during forebrain morphogenesis

    PubMed Central

    Cavodeassi, Florencia; Ivanovitch, Kenzo; Wilson, Stephen W.

    2013-01-01

    During forebrain morphogenesis, there is extensive reorganisation of the cells destined to form the eyes, telencephalon and diencephalon. Little is known about the molecular mechanisms that regulate region-specific behaviours and that maintain the coherence of cell populations undergoing specific morphogenetic processes. In this study, we show that the activity of the Eph/Ephrin signalling pathway maintains segregation between the prospective eyes and adjacent regions of the anterior neural plate during the early stages of forebrain morphogenesis in zebrafish. Several Ephrins and Ephs are expressed in complementary domains in the prospective forebrain and combinatorial abrogation of their activity results in incomplete segregation of the eyes and telencephalon and in defective evagination of the optic vesicles. Conversely, expression of exogenous Ephs or Ephrins in regions of the prospective forebrain where they are not usually expressed changes the adhesion properties of the cells, resulting in segregation to the wrong domain without changing their regional fate. The failure of eye morphogenesis in rx3 mutants is accompanied by a loss of complementary expression of Ephs and Ephrins, suggesting that this pathway is activated downstream of the regional fate specification machinery to establish boundaries between domains undergoing different programmes of morphogenesis. PMID:24026122

  14. A critical role for transcription factor Smad4 in T cell function that is independent of transforming growth factor β receptor signaling.

    PubMed

    Gu, Ai-Di; Zhang, Song; Wang, Yunqi; Xiong, Hui; Curtis, Thomas A; Wan, Yisong Y

    2015-01-20

    Transforming growth factor-beta (TGF-β) suppresses T cell function to maintain self-tolerance and to promote tumor immune evasion. Yet how Smad4, a transcription factor component of TGF-β signaling, regulates T cell function remains unclear. Here we have demonstrated an essential role for Smad4 in promoting T cell function during autoimmunity and anti-tumor immunity. Smad4 deletion rescued the lethal autoimmunity resulting from transforming growth factor-beta receptor (TGF-βR) deletion and compromised T-cell-mediated tumor rejection. Although Smad4 was dispensable for T cell generation, homeostasis, and effector function, it was essential for T cell proliferation after activation in vitro and in vivo. The transcription factor Myc was identified to mediate Smad4-controlled T cell proliferation. This study thus reveals a requirement of Smad4 for T-cell-mediated autoimmunity and tumor rejection, which is beyond the current paradigm. It highlights a TGF-βR-independent role for Smad4 in promoting T cell function, autoimmunity, and anti-tumor immunity. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Robo4 maintains vessel integrity and inhibits angiogenesis by interacting with UNC5B.

    PubMed

    Koch, Alexander W; Mathivet, Thomas; Larrivée, Bruno; Tong, Raymond K; Kowalski, Joe; Pibouin-Fragner, Laurence; Bouvrée, Karine; Stawicki, Scott; Nicholes, Katrina; Rathore, Nisha; Scales, Suzie J; Luis, Elizabeth; del Toro, Raquel; Freitas, Catarina; Bréant, Christiane; Michaud, Annie; Corvol, Pierre; Thomas, Jean-Léon; Wu, Yan; Peale, Franklin; Watts, Ryan J; Tessier-Lavigne, Marc; Bagri, Anil; Eichmann, Anne

    2011-01-18

    Robo4 is an endothelial cell-specific member of the Roundabout axon guidance receptor family. To identify Robo4 binding partners, we performed a protein-protein interaction screen with the Robo4 extracellular domain. We find that Robo4 specifically binds to UNC5B, a vascular Netrin receptor, revealing unexpected interactions between two endothelial guidance receptors. We show that Robo4 maintains vessel integrity by activating UNC5B, which inhibits signaling downstream of vascular endothelial growth factor (VEGF). Function-blocking monoclonal antibodies against Robo4 and UNC5B increase angiogenesis and disrupt vessel integrity. Soluble Robo4 protein inhibits VEGF-induced vessel permeability and rescues barrier defects in Robo4(-/-) mice, but not in mice treated with anti-UNC5B. Thus, Robo4-UNC5B signaling maintains vascular integrity by counteracting VEGF signaling in endothelial cells, identifying a novel function of guidance receptor interactions in the vasculature. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Noncanonical transforming growth factor β signaling in scleroderma fibrosis

    PubMed Central

    Trojanowska, Maria

    2014-01-01

    Purpose of review Persistent transforming growth factor β (TGF-β) signaling is the major factor contributing to scleroderma (SSc) fibrosis. This review will summarize recent progress on the noncanonical TGF-β signaling pathways and their role in SSc fibrosis. Recent findings Canonical TGF-β signaling involves activation of the TGF-β receptors and downstream signal transducers Smad2/3. The term noncanonical TGF-β signaling includes a variety of intracellular signaling pathways activated by TGF-β independently of Smad2/3 activation. There is evidence that these pathways play important role in SSc fibrosis. In a subset of SSc fibroblasts, a multiligand receptor complex consisting of TGF-β and CCN2 receptors drives constitutive activation of the Smad1 pathway. CCN2 is also a primary effector of this pathway, thus establishing an autocrine loop that amplifies TGF-β signaling. SSc fibroblasts also demonstrate reduced expression of endogenous antagonists of TGF-β signaling including transcriptional repressors, Friend leukemia integration-1 and perixosome proliferator-activated receptor-γ, as well as inhibitor of Smad3 phosphorylation, PTEN. PTEN is a key mediator of the cross-talk between the sphingosine kinase and the TGF-β pathways. Summary Discovery of the role of noncanonical TGF-β signaling in fibrosis offers new molecular targets for the antifibrotic therapies. Due to the heterogeneous nature of SSc, knowledge of these pathways could help to tailor the therapy to the individual patient depending on the activation status of a specific profibrotic pathway. PMID:19713852

  17. E2F Activators Signal and Maintain Centrosome Amplification in Breast Cancer Cells

    PubMed Central

    Lee, Mi-Young; Moreno, Carlos S.

    2014-01-01

    Centrosomes ensure accurate chromosome segregation by directing spindle bipolarity. Loss of centrosome regulation results in centrosome amplification, multipolar mitosis and aneuploidy. Since centrosome amplification is common in premalignant lesions and breast tumors, it is proposed to play a central role in breast tumorigenesis, a hypothesis that remains to be tested. The coordination between the cell and centrosome cycles is of paramount importance to maintain normal centrosome numbers, and the E2Fs may be responsible for regulating these cycles. However, the role of E2F activators in centrosome amplification is unclear. Because E2Fs are deregulated in Her2+ cells displaying centrosome amplification, we addressed whether they signal this abnormal process. Knockdown of E2F1 or E2F3 in Her2+ cells decreased centrosome amplification without significantly affecting cell cycle progression, whereas the overexpression of E2F1, E2F2, or E2F3 increased centrosome amplification in MCF10A mammary epithelial cells. Our results revealed that E2Fs affect the expression of proteins, including Nek2 and Plk4, known to influence the cell/centrosome cycles and mitosis. Downregulation of E2F3 resulted in cell death and delays/blocks in cytokinesis, which was reversed by Nek2 overexpression. Nek2 overexpression enhanced centrosome amplification in Her2+ breast cancer cells silenced for E2F3, revealing a role for the E2F activators in maintaining centrosome amplification in part through Nek2. PMID:24797070

  18. E2F activators signal and maintain centrosome amplification in breast cancer cells.

    PubMed

    Lee, Mi-Young; Moreno, Carlos S; Saavedra, Harold I

    2014-07-01

    Centrosomes ensure accurate chromosome segregation by directing spindle bipolarity. Loss of centrosome regulation results in centrosome amplification, multipolar mitosis and aneuploidy. Since centrosome amplification is common in premalignant lesions and breast tumors, it is proposed to play a central role in breast tumorigenesis, a hypothesis that remains to be tested. The coordination between the cell and centrosome cycles is of paramount importance to maintain normal centrosome numbers, and the E2Fs may be responsible for regulating these cycles. However, the role of E2F activators in centrosome amplification is unclear. Because E2Fs are deregulated in Her2(+) cells displaying centrosome amplification, we addressed whether they signal this abnormal process. Knockdown of E2F1 or E2F3 in Her2(+) cells decreased centrosome amplification without significantly affecting cell cycle progression, whereas the overexpression of E2F1, E2F2, or E2F3 increased centrosome amplification in MCF10A mammary epithelial cells. Our results revealed that E2Fs affect the expression of proteins, including Nek2 and Plk4, known to influence the cell/centrosome cycles and mitosis. Downregulation of E2F3 resulted in cell death and delays/blocks in cytokinesis, which was reversed by Nek2 overexpression. Nek2 overexpression enhanced centrosome amplification in Her2(+) breast cancer cells silenced for E2F3, revealing a role for the E2F activators in maintaining centrosome amplification in part through Nek2.

  19. EGFR signaling is critical for maintaining the superficial layer of articular cartilage and preventing osteoarthritis initiation

    PubMed Central

    Jia, Haoruo; Ma, Xiaoyuan; Tong, Wei; Doyran, Basak; Sun, Zeyang; Wang, Luqiang; Zhang, Xianrong; Zhou, Yilu; Badar, Farid; Chandra, Abhishek; Lu, X. Lucas; Xia, Yang; Han, Lin; Enomoto-Iwamoto, Motomi; Qin, Ling

    2016-01-01

    Osteoarthritis (OA) is the most common joint disease, characterized by progressive destruction of the articular cartilage. The surface of joint cartilage is the first defensive and affected site of OA, but our knowledge of genesis and homeostasis of this superficial zone is scarce. EGFR signaling is important for tissue homeostasis. Immunostaining revealed that its activity is mostly dominant in the superficial layer of healthy cartilage but greatly diminished when OA initiates. To evaluate the role of EGFR signaling in the articular cartilage, we studied a cartilage-specific Egfr-deficient (CKO) mouse model (Col2-Cre EgfrWa5/flox). These mice developed early cartilage degeneration at 6 mo of age. By 2 mo of age, although their gross cartilage morphology appears normal, CKO mice had a drastically reduced number of superficial chondrocytes and decreased lubricant secretion at the surface. Using superficial chondrocyte and cartilage explant cultures, we demonstrated that EGFR signaling is critical for maintaining the number and properties of superficial chondrocytes, promoting chondrogenic proteoglycan 4 (Prg4) expression, and stimulating the lubrication function of the cartilage surface. In addition, EGFR deficiency greatly disorganized collagen fibrils in articular cartilage and strikingly reduced cartilage surface modulus. After surgical induction of OA at 3 mo of age, CKO mice quickly developed the most severe OA phenotype, including a complete loss of cartilage, extremely high surface modulus, subchondral bone plate thickening, and elevated joint pain. Taken together, our studies establish EGFR signaling as an important regulator of the superficial layer during articular cartilage development and OA initiation. PMID:27911782

  20. A compartmentalized phosphoinositide signaling axis at cilia is regulated by INPP5E to maintain cilia and promote Sonic Hedgehog medulloblastoma.

    PubMed

    Conduit, S E; Ramaswamy, V; Remke, M; Watkins, D N; Wainwright, B J; Taylor, M D; Mitchell, C A; Dyson, J M

    2017-10-26

    Sonic Hedgehog (SHH) signaling at primary cilia drives the proliferation and progression of a subset of medulloblastomas, the most common malignant paediatric brain tumor. Severe side effects associated with conventional treatments and resistance to targeted therapies has led to the need for new strategies. SHH signaling is dependent on primary cilia for signal transduction suggesting the potential for cilia destabilizing mechanisms as a therapeutic target. INPP5E is an inositol polyphosphate 5-phosphatase that hydrolyses PtdIns(4,5)P 2 and more potently, the phosphoinositide (PI) 3-kinase product PtdIns(3,4,5)P 3 . INPP5E promotes SHH signaling during embryonic development via PtdIns(4,5)P 2 hydrolysis at cilia, that in turn regulates the cilia recruitment of the SHH suppressor GPR161. However, the role INPP5E plays in cancer is unknown and the contribution of PI3-kinase signaling to cilia function is little characterized. Here, we reveal INPP5E promotes SHH signaling in SHH medulloblastoma by negatively regulating a cilia-compartmentalized PI3-kinase signaling axis that maintains primary cilia on tumor cells. Conditional deletion of Inpp5e in a murine model of constitutively active Smoothened-driven medulloblastoma slowed tumor progression, suppressed cell proliferation, reduced SHH signaling and promoted tumor cell cilia loss. PtdIns(3,4,5)P 3 , its effector pAKT and the target pGSK3β, which when non-phosphorylated promotes cilia assembly/stability, localized to tumor cell cilia. The number of PtdIns(3,4,5)P 3 /pAKT/pGSK3β-positive cilia was increased in cultured Inpp5e-null tumor cells relative to controls. PI3-kinase inhibition or expression of wild-type, but not catalytically inactive HA-INPP5E partially rescued cilia loss in Inpp5e-null tumor cells in vitro. INPP5E mRNA and copy number were reduced in human SHH medulloblastoma compared to other molecular subtypes and consistent with the murine model, reduced INPP5E was associated with improved overall

  1. Control of germline stem cell self-renewal and differentiation in the Drosophila ovary: concerted actions of niche signals and intrinsic factors.

    PubMed

    Xie, Ting

    2013-01-01

    In the Drosophila ovary, germline stem cells (GSCs) physically interact with their niche composed of terminal filament cells, cap cells, and possibly GSC-contacting escort cells (ECs). A GSC divides to generate a self-renewing stem cell that remains in the niche and a differentiating daughter that moves away from the niche. The GSC niche provides a bone morphogenetic protein (BMP) signal that maintains GSC self-renewal by preventing stem cell differentiation via repression of the differentiation-promoting gene bag of marbles (bam). In addition, it expresses E-cadherin, which mediates cell adhesion for anchoring GSCs in the niche, enabling continuous self-renewal. GSCs themselves also express different classes of intrinsic factors, including signal transducers, transcription factors, chromatin remodeling factors, translation regulators, and miRNAs, which control self-renewal by strengthening interactions with the niche and repressing various differentiation pathways. Differentiated GSC daughters, known as cystoblasts (CBs), also express distinct classes of intrinsic factors to inhibit self-renewal and promote germ cell differentiation. Surprisingly, GSC progeny are also dependent on their surrounding ECs for proper differentiation at least partly by preventing BMP from diffusing to the differentiated germ cell zone and by repressing ectopic BMP expression. Therefore, both GSC self-renewal and CB differentiation are controlled by collaborative actions of extrinsic signals and intrinsic factors. Copyright © 2012 Wiley Periodicals, Inc.

  2. Characterization of a diffusible signaling factor from Xylella fastidiosa.

    PubMed

    Beaulieu, Ellen D; Ionescu, Michael; Chatterjee, Subhadeep; Yokota, Kenji; Trauner, Dirk; Lindow, Steven

    2013-01-08

    Cell-cell signaling in Xylella fastidiosa has been implicated in the coordination of traits enabling colonization in plant hosts as well as insect vectors. This cell density-dependent signaling has been attributed to a diffusible signaling factor (DSF) produced by the DSF synthase RpfF. DSF produced by related bacterial species are unsaturated fatty acids, but that of X. fastidiosa was thought to be different from those of other taxa. We describe here the isolation and characterization of an X. fastidiosa DSF (XfDSF) as 2(Z)-tetradecenoic acid. This compound was isolated both from recombinant Erwinia herbicola expressing X. fastidiosa rpfF and from an X. fastidiosa rpfC deletion mutant that overproduces DSF. Since an rpfF mutant is impaired in biofilm formation and underexpresses the hemagglutinin-like protein-encoding genes hxfA and hxfB, we demonstrate that these traits can be restored by ca. 0.5 µM XfDSF but not by myristic acid, the fully saturated tetradecenoic acid. A phoA-based X. fastidiosa biosensor that assesses DSF-dependent expression of hxfA or hxfB revealed a high level of molecular specificity of DSF signaling. X. fastidiosa causes diseases in many important plants, including grape, where it incites Pierce's disease. Virulence of X. fastidiosa for grape is coordinated by cell-cell signaling molecules, designated DSF (Diffusible Signaling Factor). Mutants blocked in DSF production are hypervirulent for grape, suggesting that virulence is suppressed upon DSF accumulation and that disease could be controlled by artificial elevation of the DSF level in plants. In this work, we describe the isolation of the DSF produced by X. fastidiosa and the verification of its biological activity as an antivirulence factor. We also have developed X. fastidiosa DSF biosensors to evaluate the specificity of cell-cell signaling to be investigated.

  3. Burkholderia Diffusible Signal Factor Signals to Francisella novicida To Disperse Biofilm and Increase Siderophore Production

    PubMed Central

    Dean, Scott N.; Chung, Myung-Chul

    2015-01-01

    In many bacteria, the ability to modulate biofilm production relies on specific signaling molecules that are either self-produced or made by neighboring microbes within the ecological niche. We analyzed the potential interspecies signaling effect of the Burkholderia diffusible signal factor (BDSF) on Francisella novicida, a model organism for Francisella tularensis, and demonstrated that BDSF both inhibits the formation and causes the dispersion of Francisella biofilm. Specificity was demonstrated for the cis versus the trans form of BDSF. Using transcriptome sequencing, quantitative reverse transcription-PCR, and activity assays, we found that BDSF altered the expression of many F. novicida genes, including genes involved in biofilm formation, such as chitinases. Using a chitinase inhibitor, the antibiofilm activity of BDSF was also shown to be chitinase dependent. In addition, BDSF caused an increase in RelA expression and increased levels of (p)ppGpp, leading to decreased biofilm production. These results support our observation that exposure of F. novicida to BDSF causes biofilm dispersal. Furthermore, BDSF upregulated the genes involved in iron acquisition (figABCD), increasing siderophore production. Thus, this study provides evidence for a potential role and mechanism of diffusible signal factor (DSF) signaling in the genus Francisella and suggests the possibility of interspecies signaling between Francisella and other bacteria. Overall, this study suggests that in response to the interspecies DSF signal, F. novicida can alter its gene expression and regulate its biofilm formation. PMID:26231649

  4. Hepatocyte Growth Factor-c-MET Signaling Mediates the Development of Nonsensory Structures of the Mammalian Cochlea and Hearing.

    PubMed

    Shibata, Shumei; Miwa, Toru; Wu, Hsiao-Huei; Levitt, Pat; Ohyama, Takahiro

    2016-08-03

    The stria vascularis is a nonsensory structure that is essential for auditory hair cell function by maintaining potassium concentration of the scala media. During mouse embryonic development, a subpopulation of neural crest cell-derived melanocytes migrates and incorporates into a subregion of the cochlear epithelium, forming the intermediate cell layer of the stria vascularis. The relation of this developmental process to stria vascularis function is currently unknown. In characterizing the molecular differentiation of developing peripheral auditory structures, we discovered that hepatocyte growth factor (Hgf) is expressed in the future stria vascularis of the cochlear epithelium. Its receptor tyrosine kinase, c-Met, is expressed in the cochlear epithelium and melanocyte-derived intermediate cells in the stria vascularis. Genetic dissection of HGF signaling via c-MET reveals that the incorporation of the melanocytes into the future stria vascularis of the cochlear duct requires c-MET signaling. In addition, inactivation of either the ligand or receptor developmentally resulted in a profound hearing loss at young adult stages. These results suggest a novel connection between HGF signaling and deafness via melanocyte deficiencies. We found the roles of hepatocyte growth factor (HGF) signaling in stria vascularis development for the first time and that lack of HGF signaling in the inner ear leads to profound hearing loss in the mouse. Our findings reveal a novel mechanism that may underlie human deafness DFNB39 and DFNB97. Our findings reveal an additional example of context-dependent c-MET signaling diversity, required here for proper cellular invasion developmentally that is essential for specific aspects of auditory-related organogenesis. Copyright © 2016 the authors 0270-6474/16/368200-10$15.00/0.

  5. Maintaining protein composition in cilia.

    PubMed

    Stephen, Louise A; Elmaghloob, Yasmin; Ismail, Shehab

    2017-12-20

    The primary cilium is a sensory organelle that is vital in regulating several signalling pathways. Unlike most organelles cilia are open to the rest of the cell, not enclosed by membranes. The distinct protein composition is crucial to the function of cilia and many signalling proteins and receptors are specifically concentrated within distinct compartments. To maintain this composition, a mechanism is required to deliver proteins to the cilium whilst another must counter the entropic tendency of proteins to distribute throughout the cell. The combination of the two mechanisms should result in the concentration of ciliary proteins to the cilium. In this review we will look at different cellular mechanisms that play a role in maintaining the distinct composition of cilia, including regulation of ciliary access and trafficking of ciliary proteins to, from and within the cilium.

  6. Context matters: sexual signaling loss in digital organisms

    PubMed Central

    Weigel, Emily G; Testa, Nicholas D; Peer, Alex; Garnett, Sara C

    2015-01-01

    Sexual signals are important in attracting and choosing mates; however, these signals and their associated preferences are often costly and frequently lost. Despite the prevalence of signaling system loss in many taxa, the factors leading to signal loss remain poorly understood. Here, we test the hypothesis that complexity in signal loss scenarios is due to the context-dependent nature of the many factors affecting signal loss itself. Using the Avida digital life platform, we evolved 50 replicates of ∼250 lineages, each with a unique combination of parameters, including whether signaling is obligate or facultative; genetic linkage between signaling and receiving genes; population size; and strength of preference for signals. Each of these factors ostensibly plays a crucial role in signal loss, but was found to do so only under specific conditions. Under obligate signaling, genetic linkage, but not population size, influenced signal loss; under facultative signaling, genetic linkage does not have significant influence. Somewhat surprisingly, only a total loss of preference in the obligate signaling populations led to total signal loss, indicating that even a modest amount of preference is enough to maintain signaling systems. Strength of preference proved to be the strongest single force preventing signal loss, as it consistently overcame the potential effects of drift within our study. Our findings suggest that signaling loss is often dependent on not just preference for signals, population size, and genetic linkage, but also whether signals are required to initiate mating. These data provide an understanding of the factors (and their interactions) that may facilitate the maintenance of sexual signals. PMID:26380700

  7. Neurotrophic factors switch between two signaling pathways that trigger axonal growth.

    PubMed

    Paveliev, Mikhail; Lume, Maria; Velthut, Agne; Phillips, Matthew; Arumäe, Urmas; Saarma, Mart

    2007-08-01

    Integration of multiple inputs from the extracellular environment, such as extracellular matrix molecules and growth factors, is a crucial process for cell function and information processing in multicellular organisms. Here we demonstrate that co-stimulation of dorsal root ganglion neurons with neurotrophic factors (NTFs) - glial-cell-line-derived neurotrophic factor, neurturin or nerve growth factor - and laminin leads to axonal growth that requires activation of Src family kinases (SFKs). A different, SFK-independent signaling pathway evokes axonal growth on laminin in the absence of the NTFs. By contrast, axonal branching is regulated by SFKs both in the presence and in the absence of NGF. We propose and experimentally verify a Boolean model of the signaling network triggered by NTFs and laminin. Our results demonstrate that NTFs provide an environmental cue that triggers a switch between separate pathways in the cell signaling network.

  8. Fibroblast growth factor signaling in skeletal development and disease

    PubMed Central

    Ornitz, David M.; Marie, Pierre J.

    2015-01-01

    Fibroblast growth factor (FGF) signaling pathways are essential regulators of vertebrate skeletal development. FGF signaling regulates development of the limb bud and formation of the mesenchymal condensation and has key roles in regulating chondrogenesis, osteogenesis, and bone and mineral homeostasis. This review updates our review on FGFs in skeletal development published in Genes & Development in 2002, examines progress made on understanding the functions of the FGF signaling pathway during critical stages of skeletogenesis, and explores the mechanisms by which mutations in FGF signaling molecules cause skeletal malformations in humans. Links between FGF signaling pathways and other interacting pathways that are critical for skeletal development and could be exploited to treat genetic diseases and repair bone are also explored. PMID:26220993

  9. SPSB1, a Novel Negative Regulator of the Transforming Growth FactorSignaling Pathway Targeting the Type II Receptor.

    PubMed

    Liu, Sheng; Nheu, Thao; Luwor, Rodney; Nicholson, Sandra E; Zhu, Hong-Jian

    2015-07-17

    Appropriate cellular signaling is essential to control cell proliferation, differentiation, and cell death. Aberrant signaling can have devastating consequences and lead to disease states, including cancer. The transforming growth factor-β (TGF-β) signaling pathway is a prominent signaling pathway that has been tightly regulated in normal cells, whereas its deregulation strongly correlates with the progression of human cancers. The regulation of the TGF-β signaling pathway involves a variety of physiological regulators. Many of these molecules act to alter the activity of Smad proteins. In contrast, the number of molecules known to affect the TGF-β signaling pathway at the receptor level is relatively low, and there are no known direct modulators for the TGF-β type II receptor (TβRII). Here we identify SPSB1 (a Spry domain-containing Socs box protein) as a novel regulator of the TGF-β signaling pathway. SPSB1 negatively regulates the TGF-β signaling pathway through its interaction with both endogenous and overexpressed TβRII (and not TβRI) via its Spry domain. As such, TβRII and SPSB1 co-localize on the cell membrane. SPSB1 maintains TβRII at a low level by enhancing the ubiquitination levels and degradation rates of TβRII through its Socs box. More importantly, silencing SPSB1 by siRNA results in enhanced TGF-β signaling and migration and invasion of tumor cells. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  10. Fibroblast growth factor signaling in skeletal development and disease.

    PubMed

    Ornitz, David M; Marie, Pierre J

    2015-07-15

    Fibroblast growth factor (FGF) signaling pathways are essential regulators of vertebrate skeletal development. FGF signaling regulates development of the limb bud and formation of the mesenchymal condensation and has key roles in regulating chondrogenesis, osteogenesis, and bone and mineral homeostasis. This review updates our review on FGFs in skeletal development published in Genes & Development in 2002, examines progress made on understanding the functions of the FGF signaling pathway during critical stages of skeletogenesis, and explores the mechanisms by which mutations in FGF signaling molecules cause skeletal malformations in humans. Links between FGF signaling pathways and other interacting pathways that are critical for skeletal development and could be exploited to treat genetic diseases and repair bone are also explored. © 2015 Ornitz and Marie; Published by Cold Spring Harbor Laboratory Press.

  11. Growth factors, nutrient signaling, and cardiovascular aging.

    PubMed

    Fontana, Luigi; Vinciguerra, Manlio; Longo, Valter D

    2012-04-13

    Growth factors regulated by specific macronutrients have been shown to promote aging and accelerate mortality in the majority of the organisms studied. In particular, the enzymes activated by growth hormone, insulin, and insulin-like growth factor-1 in mammals and their orthologs in simple model organisms represent perhaps the best-understood proteins involved in the aging process. Dietary restriction, which reduces the level of insulin-like growth factor-1 and of other growth factors, has been associated with protection from diabetes, cancer, and cardiovascular diseases, and deficiencies in growth hormone signaling and insulin-like growth factor-1 are strongly associated with protection from cancer and diabetes in both mice and humans; however, their role in cardiac function and cardiovascular diseases is controversial. Here, we review the link between growth factors, cardiac function, and heart disease with focus on the cardioprotective and sensitizing effect of growth factors in both model organisms and humans.

  12. Persistent tumor necrosis factor signaling in normal human fibroblasts prevents the complete resynthesis of I kappa B-alpha.

    PubMed

    Poppers, D M; Schwenger, P; Vilcek, J

    2000-09-22

    Transcription factor NF-kappa B is normally sequestered in the cytoplasm, complexed with I kappa B inhibitory proteins. Tumor necrosis factor (TNF) and interleukin-1 induce I kappa B-alpha phosphorylation, leading to I kappa B-alpha degradation and translocation of NF-kappa B to the nucleus where it activates genes important in inflammatory and immune responses. TNF and interleukin-1 actions are typically terminated by desensitization, and I kappa B-alpha reappearance normally occurs within 30-60 min. We found that in normal human FS-4 fibroblasts maintained in the presence of TNF, I kappa B-alpha protein failed to return to base-line levels for up to 15 h. Removal of TNF at any time during the 15-h period resulted in complete I kappa B-alpha resynthesis, suggesting that I kappa B-alpha reappearance was prevented by continued TNF signaling. Long term exposure of FS-4 fibroblasts to TNF led to a persistent presence of I kappa B-alpha mRNA, sustained I kappa B kinase activation, continuous proteasome-mediated degradation of I kappa B-alpha, and sustained nuclear localization of NF-kappa B. Continuous exposure of FS-4 cells to TNF did not lead to a sustained activation of p38 or ERK mitogen-activated protein kinases, suggesting that not all TNF-induced signaling pathways are persistently activated. These findings challenge the notion that all cytokine-mediated signals are rapidly terminated by desensitization and illustrate the need to elucidate the process of deactivation of TNF-induced signaling.

  13. WRKY Transcription Factors: Key Components in Abscisic Acid Signaling

    DTIC Science & Technology

    2011-01-01

    Review article WRKY transcription factors : key components in abscisic acid signalling Deena L. Rushton1, Prateek Tripathi1, Roel C. Rabara1, Jun Lin1...May 2011. *Correspondence (Tel +605 688 5749; fax +605 688 5624; email paul.rushton@sdstate.edu) Keywords: abscisic acid, WRKY transcription factor ...seed germination, drought, abiotic stress. Summary WRKY transcription factors (TFs) are key regulators of many plant processes, including the responses

  14. Insulin-Like Growth Factor Receptor Signaling is Necessary for Epidermal Growth Factor Mediated Proliferation of SVZ Neural Precursors in vitro Following Neonatal Hypoxia–Ischemia

    PubMed Central

    Alagappan, Dhivyaa; Ziegler, Amber N.; Chidambaram, Shravanthi; Min, Jungsoo; Wood, Teresa L.; Levison, Steven W.

    2014-01-01

    In this study, we assessed the importance of insulin-like growth factor (IGF) and epidermal growth factor (EGF) receptor co-signaling for rat neural precursor (NP) cell proliferation and self-renewal in the context of a developmental brain injury that is associated with cerebral palsy. Consistent with previous studies, we found that there is an increase in the in vitro growth of subventricular zone NPs isolated acutely after cerebral hypoxia–ischemia; however, when cultured in medium that is insufficient to stimulate the IGF type 1 receptor, neurosphere formation and the proliferative capacity of those NPs was severely curtailed. This reduced growth capacity could not be attributed simply to failure to survive. The growth and self-renewal of the NPs could be restored by addition of both IGF-I and IGF-II. Since the size of the neurosphere is predominantly due to cell proliferation we hypothesized that the IGFs were regulating progression through the cell cycle. Analyses of cell cycle progression revealed that IGF-1R activation together with EGFR co-signaling decreased the percentage of cells in G1 and enhanced cell progression into S and G2. This was accompanied by increases in expression of cyclin D1, phosphorylated histone 3, and phosphorylated Rb. Based on these data, we conclude that coordinate signaling between the EGF receptor and the IGF type 1 receptor is necessary for the normal proliferation of NPs as well as for their reactive expansion after injury. These data indicate that manipulations that maintain or amplify IGF signaling in the brain during recovery from developmental brain injuries will enhance the production of new brain cells to improve neurological function in children who are at risk for developing cerebral palsy. PMID:24904523

  15. Redox-dependent regulation of epidermal growth factor receptor signaling.

    PubMed

    Heppner, David E; van der Vliet, Albert

    2016-08-01

    Tyrosine phosphorylation-dependent cell signaling represents a unique feature of multicellular organisms, and is important in regulation of cell differentiation and specialized cell functions. Multicellular organisms also contain a diverse family of NADPH oxidases (NOXs) that have been closely linked with tyrosine kinase-based cell signaling and regulate tyrosine phosphorylation via reversible oxidation of cysteine residues that are highly conserved within many proteins involved in this signaling pathway. An example of redox-regulated tyrosine kinase signaling involves the epidermal growth factor receptor (EGFR), a widely studied receptor system with diverse functions in normal cell biology as well as pathologies associated with oxidative stress such as cancer. The purpose of this Graphical Redox Review is to highlight recently emerged concepts with respect to NOX-dependent regulation of this important signaling pathway. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  16. Transforming growth factor β induces bone marrow mesenchymal stem cell migration via noncanonical signals and N-cadherin.

    PubMed

    Dubon, Maria Jose; Yu, Jinyeong; Choi, Sanghyuk; Park, Ki-Sook

    2018-01-01

    Transforming growth factor-beta (TGF-β) induces the migration and mobilization of bone marrow-derived mesenchymal stem cells (BM-MSCs) to maintain bone homeostasis during bone remodeling and facilitate the repair of peripheral tissues. Although many studies have reported the mechanisms through which TGF-β mediates the migration of various types of cells, including cancer cells, the intrinsic cellular mechanisms underlying cellular migration, and mobilization of BM-MSCs mediated by TGF-β are unclear. In this study, we showed that TGF-β activated noncanonical signaling molecules, such as Akt, extracellular signal-regulated kinase 1/2 (ERK1/2), focal adhesion kinase (FAK), and p38, via TGF-β type I receptor in human BM-MSCs and murine BM-MSC-like ST2 cells. Inhibition of Rac1 by NSC23766 and Src by PP2 resulted in impaired TGF-β-mediated migration. These results suggested that the Smad-independent, noncanonical signals activated by TGF-β were necessary for migration. We also showed that N-cadherin-dependent intercellular interactions were required for TGF-β-mediated migration using functional inhibition of N-cadherin with EDTA treatment and a neutralizing antibody (GC-4 antibody) or siRNA-mediated knockdown of N-cadherin. However, N-cadherin knockdown did not affect the global activation of noncanonical signals in response to TGF-β. Therefore, these results suggested that the migration of BM-MSCs in response to TGF-β was mediated through N-cadherin and noncanonical TGF-β signals. © 2017 Wiley Periodicals, Inc.

  17. Ergonomics Contribution in Maintainability

    NASA Astrophysics Data System (ADS)

    Teymourian, Kiumars; Seneviratne, Dammika; Galar, Diego

    2017-09-01

    The objective of this paper is to describe an ergonomics contribution in maintainability. The economical designs, inputs and training helps to increase the maintainability indicators for industrial devices. This analysis can be helpful, among other cases, to compare systems, to achieve a better design regarding maintainability requirements, to improve this maintainability under specific industrial environment and to foresee maintainability problems due to eventual changes in a device operation conditions. With this purpose, this work first introduces the notion of ergonomics and human factors, maintainability and the implementation of assessment of human postures, including some important postures to perform maintenance activities. A simulation approach is used to identify the critical posture of the maintenance personnel and implements the defined postures with minimal loads on the personnel who use the equipment in a practical scenario. The simulation inputs are given to the designers to improve the workplace/equipment in order to high level of maintainability. Finally, the work concludes summarizing the more significant aspects and suggesting future research.

  18. A class I ADP-ribosylation factor GTPase-activating protein is critical for maintaining directional root hair growth in Arabidopsis.

    PubMed

    Yoo, Cheol-Min; Wen, Jiangqi; Motes, Christy M; Sparks, J Alan; Blancaflor, Elison B

    2008-08-01

    Membrane trafficking and cytoskeletal dynamics are important cellular processes that drive tip growth in root hairs. These processes interact with a multitude of signaling pathways that allow for the efficient transfer of information to specify the direction in which tip growth occurs. Here, we show that AGD1, a class I ADP ribosylation factor GTPase-activating protein, is important for maintaining straight growth in Arabidopsis (Arabidopsis thaliana) root hairs, since mutations in the AGD1 gene resulted in wavy root hair growth. Live cell imaging of growing agd1 root hairs revealed bundles of endoplasmic microtubules and actin filaments extending into the extreme tip. The wavy phenotype and pattern of cytoskeletal distribution in root hairs of agd1 partially resembled that of mutants in an armadillo repeat-containing kinesin (ARK1). Root hairs of double agd1 ark1 mutants were more severely deformed compared with single mutants. Organelle trafficking as revealed by a fluorescent Golgi marker was slightly inhibited, and Golgi stacks frequently protruded into the extreme root hair apex of agd1 mutants. Transient expression of green fluorescent protein-AGD1 in tobacco (Nicotiana tabacum) epidermal cells labeled punctate bodies that partially colocalized with the endocytic marker FM4-64, while ARK1-yellow fluorescent protein associated with microtubules. Brefeldin A rescued the phenotype of agd1, indicating that the altered activity of an AGD1-dependent ADP ribosylation factor contributes to the defective growth, organelle trafficking, and cytoskeletal organization of agd1 root hairs. We propose that AGD1, a regulator of membrane trafficking, and ARK1, a microtubule motor, are components of converging signaling pathways that affect cytoskeletal organization to specify growth orientation in Arabidopsis root hairs.

  19. Neurodevelopmental effects of insulin-like growth factor signaling

    PubMed Central

    O’Kusky, John; Ye, Ping

    2012-01-01

    Insulin-like growth factor (IGF) signaling greatly impacts the development and growth of the central nervous system (CNS). IGF-I and IGF-II, two ligands of the IGF system, exert a wide variety of actions both during development and in adulthood, promoting the survival and proliferation of neural cells. The IGFs also influence the growth and maturation of neural cells, augmenting dendritic growth and spine formation, axon outgrowth, synaptogenesis, and myelination. Specific IGF actions, however, likely depend on cell type, developmental stage, and local microenvironmental milieu within the brain. Emerging research also indicates that alterations in IGF signaling likely contribute to the pathogenesis of some neurological disorders. This review summarizes experimental studies and shed light on the critical roles of IGF signaling, as well as its mechanisms, during CNS development. PMID:22710100

  20. Combined KIT and FGFR2b Signaling Regulates Epithelial Progenitor Expansion during Organogenesis

    PubMed Central

    Lombaert, Isabelle M.A.; Abrams, Shaun R.; Li, Li; Eswarakumar, Veraragavan P.; Sethi, Aditya J.; Witt, Robert L.; Hoffman, Matthew P.

    2013-01-01

    Summary Organ formation and regeneration require epithelial progenitor expansion to engineer, maintain, and repair the branched tissue architecture. Identifying the mechanisms that control progenitor expansion will inform therapeutic organ (re)generation. Here, we discover that combined KIT and fibroblast growth factor receptor 2b (FGFR2b) signaling specifically increases distal progenitor expansion during salivary gland organogenesis. FGFR2b signaling upregulates the epithelial KIT pathway so that combined KIT/FGFR2b signaling, via separate AKT and mitogen-activated protein kinase (MAPK) pathways, amplifies FGFR2b-dependent transcription. Combined KIT/FGFR2b signaling selectively expands the number of KIT+K14+SOX10+ distal progenitors, and a genetic loss of KIT signaling depletes the distal progenitors but also unexpectedly depletes the K5+ proximal progenitors. This occurs because the distal progenitors produce neurotrophic factors that support gland innervation, which maintains the proximal progenitors. Furthermore, a rare population of KIT+FGFR2b+ cells is present in adult glands, in which KIT signaling also regulates epithelial-neuronal communication during homeostasis. Our findings provide a framework to direct regeneration of branched epithelial organs. PMID:24371813

  1. Role of fibroblast growth factor receptor signaling in kidney development.

    PubMed

    Bates, Carlton M

    2011-08-01

    Fibroblast growth factor receptors (Fgfrs) consist of four signaling family members and one nonsignaling "decoy" receptor, Fgfr-like 1 (Fgfrl1), all of which are expressed in the developing kidney. Several studies have shown that exogenous fibroblast growth factors (Fgfs) affect growth and maturation of the metanephric mesenchyme (MM) and ureteric bud (UB) in cultured tissues. Transgenic and conditional knockout approaches in whole animals have shown that Fgfr1 and Fgfr2 (predominantly the IIIc isoform) in kidney mesenchyme are critical for early MM and UB formation. Conditional deletion of the ligand, Fgf8, in nephron precursors or global deletion of Fgfrl1 interrupts nephron formation. Fgfr2 (likely the IIIb isoform signaling downstream of Fgf7 and Fgf10) is critical for ureteric morphogenesis. Moreover, Fgfr2 appears to act independently of Frs2α (the major signaling adapter for Fgfrs) in regulating UB branching. Loss of Fgfr2 in the MM leads to many kidney and urinary tract anomalies, including vesicoureteral reflux. Thus Fgfr signaling is critical for patterning of virtually all renal lineages at early and later stages of development.

  2. Dipeptide species regulate p38MAPK–Smad3 signalling to maintain chronic myelogenous leukaemia stem cells

    PubMed Central

    Naka, Kazuhito; Jomen, Yoshie; Ishihara, Kaori; Kim, Junil; Ishimoto, Takahiro; Bae, Eun-Jin; Mohney, Robert P.; Stirdivant, Steven M.; Oshima, Hiroko; Oshima, Masanobu; Kim, Dong-Wook; Nakauchi, Hiromitsu; Takihara, Yoshihiro; Kato, Yukio; Ooshima, Akira; Kim, Seong-Jin

    2015-01-01

    Understanding the specific survival of the rare chronic myelogenous leukaemia (CML) stem cell population could provide a target for therapeutics aimed at eradicating these cells. However, little is known about how survival signalling is regulated in CML stem cells. In this study, we survey global metabolic differences between murine normal haematopoietic stem cells (HSCs) and CML stem cells using metabolomics techniques. Strikingly, we show that CML stem cells accumulate significantly higher levels of certain dipeptide species than normal HSCs. Once internalized, these dipeptide species activate amino-acid signalling via a pathway involving p38MAPK and the stemness transcription factor Smad3, which promotes CML stem cell maintenance. Importantly, pharmacological inhibition of dipeptide uptake inhibits CML stem cell activity in vivo. Our results demonstrate that dipeptide species support CML stem cell maintenance by activating p38MAPK–Smad3 signalling in vivo, and thus point towards a potential therapeutic target for CML treatment. PMID:26289811

  3. The Host Plant Metabolite Glucose Is the Precursor of Diffusible Signal Factor (DSF) Family Signals in Xanthomonas campestris

    PubMed Central

    Liu, Xiaoling; Wu, Ji'en; Lee, Jasmine; Chen, Shaohua; Cheng, Yingying; Zhang, Chunyan

    2015-01-01

    Plant pathogen Xanthomonas campestris pv. campestris produces cis-11-methyl-2-dodecenoic acid (diffusible signal factor [DSF]) as a cell-cell communication signal to regulate biofilm dispersal and virulence factor production. Previous studies have demonstrated that DSF biosynthesis is dependent on the presence of RpfF, an enoyl-coenzyme A (CoA) hydratase, but the DSF synthetic mechanism and the influence of the host plant on DSF biosynthesis are still not clear. We show here that exogenous addition of host plant juice or ethanol extract to the growth medium of X. campestris pv. campestris could significantly boost DSF family signal production. It was subsequently revealed that X. campestris pv. campestris produces not only DSF but also BDSF (cis-2-dodecenoic acid) and another novel DSF family signal, which was designated DSF-II. BDSF was originally identified in Burkholderia cenocepacia to be involved in regulation of motility, biofilm formation, and virulence in B. cenocepacia. Functional analysis suggested that DSF-II plays a role equal to that of DSF in regulation of biofilm dispersion and virulence factor production in X. campestris pv. campestris. Furthermore, chromatographic separation led to identification of glucose as a specific molecule stimulating DSF family signal biosynthesis in X. campestris pv. campestris. 13C-labeling experiments demonstrated that glucose acts as a substrate to provide a carbon element for DSF biosynthesis. The results of this study indicate that X. campestris pv. campestris could utilize a common metabolite of the host plant to enhance DSF family signal synthesis and therefore promote virulence. PMID:25681189

  4. The host plant metabolite glucose is the precursor of diffusible signal factor (DSF) family signals in Xanthomonas campestris.

    PubMed

    Deng, Yinyue; Liu, Xiaoling; Wu, Ji'en; Lee, Jasmine; Chen, Shaohua; Cheng, Yingying; Zhang, Chunyan; Zhang, Lian-Hui

    2015-04-01

    Plant pathogen Xanthomonas campestris pv. campestris produces cis-11-methyl-2-dodecenoic acid (diffusible signal factor [DSF]) as a cell-cell communication signal to regulate biofilm dispersal and virulence factor production. Previous studies have demonstrated that DSF biosynthesis is dependent on the presence of RpfF, an enoyl-coenzyme A (CoA) hydratase, but the DSF synthetic mechanism and the influence of the host plant on DSF biosynthesis are still not clear. We show here that exogenous addition of host plant juice or ethanol extract to the growth medium of X. campestris pv. campestris could significantly boost DSF family signal production. It was subsequently revealed that X. campestris pv. campestris produces not only DSF but also BDSF (cis-2-dodecenoic acid) and another novel DSF family signal, which was designated DSF-II. BDSF was originally identified in Burkholderia cenocepacia to be involved in regulation of motility, biofilm formation, and virulence in B. cenocepacia. Functional analysis suggested that DSF-II plays a role equal to that of DSF in regulation of biofilm dispersion and virulence factor production in X. campestris pv. campestris. Furthermore, chromatographic separation led to identification of glucose as a specific molecule stimulating DSF family signal biosynthesis in X. campestris pv. campestris. (13)C-labeling experiments demonstrated that glucose acts as a substrate to provide a carbon element for DSF biosynthesis. The results of this study indicate that X. campestris pv. campestris could utilize a common metabolite of the host plant to enhance DSF family signal synthesis and therefore promote virulence. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  5. Growth factors, nutrient signaling, and cardiovascular aging

    PubMed Central

    Fontana, Luigi; Vinciguerra, Manlio; Longo, Valter D.

    2012-01-01

    Growth factors regulated by specific macronutrients have been shown to promote aging and accelerate mortality in the great majority of the organisms studied. In particular, the enzymes activated by growth hormone (GH), insulin and insulin-like growth factor 1 (IGF-I) in mammals and their orthologs in simple model organisms represent perhaps the best-understood proteins involved in the aging process. Dietary restriction (DR), which reduces the level of IGF-I and of other growth factors, has been associated with protection from diabetes, cancer, and cardiovascular diseases and deficiencies in GH signaling and IGF-I are strongly associated with protection from cancer and diabetes in both mice and humans, but their role in cardiac function and cardiovascular diseases is controversial. Here we review the link between growth factors, cardiac function and heart disease with focus on the cardioprotective and sensitizing effect of growth factors in both model organisms and humans. PMID:22499903

  6. Krüppel-like factors are effectors of nuclear receptor signaling

    PubMed Central

    Knoedler, Joseph R.; Denver, Robert J.

    2015-01-01

    Binding of steroid and thyroid hormones to their cognate nuclear receptors (NRs) impacts virtually every aspect of postembryonic development, physiology and behavior, and inappropriate signaling by NRs may contribute to disease. While NRs regulate genes by direct binding to hormone response elements in the genome, their actions may depend on the activity of other transcription factors (TFs) that may or may not bind DNA. The Krüppel-like family of transcription factors (KLF) is an evolutionarily conserved class of DNA-binding proteins that influence many aspects of development and physiology. Several members of this family have been shown to play diverse roles in NR signaling. For example, KLFs 1) act as accessory transcription factors for NR actions, 2) regulate expression of NR genes, and 3) as gene products of primary NR response genes function as key players in NR-dependent transcriptional networks. In mouse models, deletion of different KLFs leads to aberrant transcriptional and physiological responses to hormones, underscoring the importance of these proteins in the regulation of hormonal signaling. Understanding the functional relationships between NRs and KLFs will yield important insights into mechanisms of NR signaling. In this review we present a conceptual framework for understanding how KLFs participate in NR signaling, and we provide examples of how these proteins function to effect hormone action. PMID:24642391

  7. Fibroblast growth factor (FGF) signaling in development and skeletal diseases.

    PubMed

    Teven, Chad M; Farina, Evan M; Rivas, Jane; Reid, Russell R

    2014-12-01

    Fibroblast growth factors (FGF) and their receptors serve many functions in both the developing and adult organism. Humans contain 18 FGF ligands and four FGF receptors (FGFR). FGF ligands are polypeptide growth factors that regulate several developmental processes including cellular proliferation, differentiation, and migration, morphogenesis, and patterning. FGF-FGFR signaling is also critical to the developing axial and craniofacial skeleton. In particular, the signaling cascade has been implicated in intramembranous ossification of cranial bones as well as cranial suture homeostasis. In the adult, FGFs and FGFRs are crucial for tissue repair. FGF signaling generally follows one of three transduction pathways: RAS/MAP kinase, PI3/AKT, or PLCγ. Each pathway likely regulates specific cellular behaviors. Inappropriate expression of FGF and improper activation of FGFRs are associated with various pathologic conditions, unregulated cell growth, and tumorigenesis. Additionally, aberrant signaling has been implicated in many skeletal abnormalities including achondroplasia and craniosynostosis. The biology and mechanisms of the FGF family have been the subject of significant research over the past 30 years. Recently, work has focused on the therapeutic targeting and potential of FGF ligands and their associated receptors. The majority of FGF-related therapy is aimed at age-related disorders. Increased understanding of FGF signaling and biology may reveal additional therapeutic roles, both in utero and postnatally. This review discusses the role of FGF signaling in general physiologic and pathologic embryogenesis and further explores it within the context of skeletal development.

  8. Fibroblast growth factor (FGF) signaling in development and skeletal diseases

    PubMed Central

    Teven, Chad M.; Farina, Evan M.; Rivas, Jane; Reid, Russell R.

    2014-01-01

    Fibroblast growth factors (FGF) and their receptors serve many functions in both the developing and adult organism. Humans contain 18 FGF ligands and four FGF receptors (FGFR). FGF ligands are polypeptide growth factors that regulate several developmental processes including cellular proliferation, differentiation, and migration, morphogenesis, and patterning. FGF-FGFR signaling is also critical to the developing axial and craniofacial skeleton. In particular, the signaling cascade has been implicated in intramembranous ossification of cranial bones as well as cranial suture homeostasis. In the adult, FGFs and FGFRs are crucial for tissue repair. FGF signaling generally follows one of three transduction pathways: RAS/MAP kinase, PI3/AKT, or PLCγ. Each pathway likely regulates specific cellular behaviors. Inappropriate expression of FGF and improper activation of FGFRs are associated with various pathologic conditions, unregulated cell growth, and tumorigenesis. Additionally, aberrant signaling has been implicated in many skeletal abnormalities including achondroplasia and craniosynostosis. The biology and mechanisms of the FGF family have been the subject of significant research over the past 30 years. Recently, work has focused on the therapeutic targeting and potential of FGF ligands and their associated receptors. The majority of FGF-related therapy is aimed at age-related disorders. Increased understanding of FGF signaling and biology may reveal additional therapeutic roles, both in utero and postnatally. This review discusses the role of FGF signaling in general physiologic and pathologic embryogenesis and further explores it within the context of skeletal development. PMID:25679016

  9. AP2/EREBP transcription factors are part of gene regulatory networks and integrate metabolic, hormonal and environmental signals in stress acclimation and retrograde signalling.

    PubMed

    Dietz, Karl-Josef; Vogel, Marc Oliver; Viehhauser, Andrea

    2010-09-01

    To optimize acclimation responses to environmental growth conditions, plants integrate and weigh a diversity of input signals. Signal integration within the signalling networks occurs at different sites including the level of transcription factor activation. Accumulating evidence assigns a major and diversified role in environmental signal integration to the family of APETALA 2/ethylene response element binding protein (AP2/EREBP) transcription factors. Presently, the Plant Transcription Factor Database 3.0 assigns 147 gene loci to this family in Arabidopsis thaliana, 200 in Populus trichocarpa and 163 in Oryza sativa subsp. japonica as compared to 13 to 14 in unicellular algae ( http://plntfdb.bio.uni-potsdam.de/v3.0/ ). AP2/EREBP transcription factors have been implicated in hormone, sugar and redox signalling in context of abiotic stresses such as cold and drought. This review exemplarily addresses present-day knowledge of selected AP2/EREBP with focus on a function in stress signal integration and retrograde signalling and defines AP2/EREBP-linked gene networks from transcriptional profiling-based graphical Gaussian models. The latter approach suggests highly interlinked functions of AP2/EREBPs in retrograde and stress signalling.

  10. Mechanisms of extracellular signal-regulated kinase/cAMP response element-binding protein/brain-derived neurotrophic factor signal transduction pathway in depressive disorder☆

    PubMed Central

    Wang, Hongyan; Zhang, Yingquan; Qiao, Mingqi

    2013-01-01

    The extracellular signal-regulated kinase/cAMP response element-binding protein/brain-derived neurotrophic factor signal transduction pathway plays an important role in the mechanism of action of antidepressant drugs and has dominated recent studies on the pathogenesis of depression. In the present review we summarize the known roles of extracellular signal-regulated kinase, cAMP response element-binding protein and brain-derived neurotrophic factor in the pathogenesis of depression and in the mechanism of action of antidepressant medicines. The extracellular signal-regulated kinase/cAMP response element-binding protein/brain-derived neurotrophic factor pathway has potential to be used as a biological index to help diagnose depression, and as such it is considered as an important new target in the treatment of depression. PMID:25206732

  11. Regulation of fibroblast growth factor receptor signalling and trafficking by Src and Eps8.

    PubMed

    Auciello, Giulio; Cunningham, Debbie L; Tatar, Tulin; Heath, John K; Rappoport, Joshua Z

    2013-01-15

    Fibroblast growth factor receptors (FGFRs) mediate a wide spectrum of cellular responses that are crucial for development and wound healing. However, aberrant FGFR activity leads to cancer. Activated growth factor receptors undergo stimulated endocytosis, but can continue to signal along the endocytic pathway. Endocytic trafficking controls the duration and intensity of signalling, and growth factor receptor signalling can lead to modifications of trafficking pathways. We have developed live-cell imaging methods for studying FGFR dynamics to investigate mechanisms that coordinate the interplay between receptor trafficking and signal transduction. Activated FGFR enters the cell following recruitment to pre-formed clathrin-coated pits (CCPs). However, FGFR activation stimulates clathrin-mediated endocytosis; FGF treatment increases the number of CCPs, including those undergoing endocytosis, and this effect is mediated by Src and its phosphorylation target Eps8. Eps8 interacts with the clathrin-mediated endocytosis machinery and depletion of Eps8 inhibits FGFR trafficking and immediate Erk signalling. Once internalized, FGFR passes through peripheral early endosomes en route to recycling and degredative compartments, through an Src- and Eps8-dependent mechanism. Thus Eps8 functions as a key coordinator in the interplay between FGFR signalling and trafficking. This work provides the first detailed mechanistic analysis of growth factor receptor clustering at the cell surface through signal transduction and endocytic trafficking. As we have characterised the Src target Eps8 as a key regulator of FGFR signalling and trafficking, and identified the early endocytic system as the site of Eps8-mediated effects, this work provides novel mechanistic insight into the reciprocal regulation of growth factor receptor signalling and trafficking.

  12. 33 CFR 118.5 - Penalty for failure to maintain.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... States who fails or refuses to maintain such lights and other signals, or to obey any of the lawful rules... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Penalty for failure to maintain. 118.5 Section 118.5 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY...

  13. Role of fibroblast growth factor receptor signaling in kidney development

    PubMed Central

    2011-01-01

    Fibroblast growth factor receptors (Fgfrs) consist of four signaling family members and one nonsignaling “decoy” receptor, Fgfr-like 1 (Fgfrl1), all of which are expressed in the developing kidney. Several studies have shown that exogenous fibroblast growth factors (Fgfs) affect growth and maturation of the metanephric mesenchyme (MM) and ureteric bud (UB) in cultured tissues. Transgenic and conditional knockout approaches in whole animals have shown that Fgfr1 and Fgfr2 (predominantly the IIIc isoform) in kidney mesenchyme are critical for early MM and UB formation. Conditional deletion of the ligand, Fgf8, in nephron precursors or global deletion of Fgfrl1 interrupts nephron formation. Fgfr2 (likely the IIIb isoform signaling downstream of Fgf7 and Fgf10) is critical for ureteric morphogenesis. Moreover, Fgfr2 appears to act independently of Frs2α (the major signaling adapter for Fgfrs) in regulating UB branching. Loss of Fgfr2 in the MM leads to many kidney and urinary tract anomalies, including vesicoureteral reflux. Thus Fgfr signaling is critical for patterning of virtually all renal lineages at early and later stages of development. PMID:21613421

  14. Aldosterone interaction with epidermal growth factor receptor signaling in MDCK cells.

    PubMed

    Gekle, Michael; Freudinger, Ruth; Mildenberger, Sigrid; Silbernagl, Stefan

    2002-04-01

    Epidermal growth factor (EGF) regulates cell proliferation, differentiation, and ion transport by using extracellular signal-regulated kinase (ERK)1/2 as a downstream signal. Furthermore, the EGF-receptor (EGF-R) is involved in signaling by G protein-coupled receptors, growth hormone, and cytokines by means of transactivation. It has been suggested that steroids interact with peptide hormones, in part, by rapid, potentially nongenomic, mechanisms. Previously, we have shown that aldosterone modulates Na(+)/H(+) exchange in Madin-Darby canine kidney (MDCK) cells by means of ERK1/2 in a way similar to growth factors. Here, we tested the hypothesis that aldosterone uses the EGF-R as a heterologous signal transducer in MDCK cells. Nanomolar concentrations of aldosterone induce a rapid increase in ERK1/2 phosphorylation, cellular Ca(2+) concentration, and Na(+)/H(+) exchange activity similar to increases induced by EGF. Furthermore, aldosterone induced a rapid increase in EGF-R-Tyr phosphorylation, and inhibition of EGF-R kinase abolished aldosterone-induced signaling. Inhibition of ERK1/2 phosphorylation reduced the Ca(2+) response, whereas prevention of Ca(2+) influx did not abolish ERK1/2 phosphorylation. Our data show that aldosterone uses the EGF-R-ERK1/2 signaling cascade to elicit its rapid effects in MDCK cells.

  15. Fibroblast Growth Factor Signaling Mediates Pulmonary Endothelial Glycocalyx Reconstitution

    PubMed Central

    Yang, Yimu; Haeger, Sarah M.; Suflita, Matthew A.; Zhang, Fuming; Dailey, Kyrie L.; Colbert, James F.; Ford, Joshay A.; Picon, Mario A.; Stearman, Robert S.; Lin, Lei; Liu, Xinyue; Han, Xiaorui; Linhardt, Robert J.

    2017-01-01

    The endothelial glycocalyx is a heparan sulfate (HS)–rich endovascular structure critical to endothelial function. Accordingly, endothelial glycocalyx degradation during sepsis contributes to tissue edema and organ injury. We determined the endogenous mechanisms governing pulmonary endothelial glycocalyx reconstitution, and if these reparative mechanisms are impaired during sepsis. We performed intravital microscopy of wild-type and transgenic mice to determine the rapidity of pulmonary endothelial glycocalyx reconstitution after nonseptic (heparinase-III mediated) or septic (cecal ligation and puncture mediated) endothelial glycocalyx degradation. We used mass spectrometry, surface plasmon resonance, and in vitro studies of human and mouse samples to determine the structure of HS fragments released during glycocalyx degradation and their impact on fibroblast growth factor receptor (FGFR) 1 signaling, a mediator of endothelial repair. Homeostatic pulmonary endothelial glycocalyx reconstitution occurred rapidly after nonseptic degradation and was associated with induction of the HS biosynthetic enzyme, exostosin (EXT)-1. In contrast, sepsis was characterized by loss of pulmonary EXT1 expression and delayed glycocalyx reconstitution. Rapid glycocalyx recovery after nonseptic degradation was dependent upon induction of FGFR1 expression and was augmented by FGF-promoting effects of circulating HS fragments released during glycocalyx degradation. Although sepsis-released HS fragments maintained this ability to activate FGFR1, sepsis was associated with the downstream absence of reparative pulmonary endothelial FGFR1 induction. Sepsis may cause vascular injury not only via glycocalyx degradation, but also by impairing FGFR1/EXT1–mediated glycocalyx reconstitution. PMID:28187268

  16. The FERONIA Receptor Kinase Maintains Cell-Wall Integrity during Salt Stress through Ca2+ Signaling.

    PubMed

    Feng, Wei; Kita, Daniel; Peaucelle, Alexis; Cartwright, Heather N; Doan, Vinh; Duan, Qiaohong; Liu, Ming-Che; Maman, Jacob; Steinhorst, Leonie; Schmitz-Thom, Ina; Yvon, Robert; Kudla, Jörg; Wu, Hen-Ming; Cheung, Alice Y; Dinneny, José R

    2018-03-05

    Cells maintain integrity despite changes in their mechanical properties elicited during growth and environmental stress. How cells sense their physical state and compensate for cell-wall damage is poorly understood, particularly in plants. Here we report that FERONIA (FER), a plasma-membrane-localized receptor kinase from Arabidopsis, is necessary for the recovery of root growth after exposure to high salinity, a widespread soil stress. The extracellular domain of FER displays tandem regions of homology with malectin, an animal protein known to bind di-glucose in vitro and important for protein quality control in the endoplasmic reticulum. The presence of malectin-like domains in FER and related receptor kinases has led to widespread speculation that they interact with cell-wall polysaccharides and can potentially serve a wall-sensing function. Results reported here show that salinity causes softening of the cell wall and that FER is necessary to sense these defects. When this function is disrupted in the fer mutant, root cells explode dramatically during growth recovery. Similar defects are observed in the mur1 mutant, which disrupts pectin cross-linking. Furthermore, fer cell-wall integrity defects can be rescued by treatment with calcium and borate, which also facilitate pectin cross-linking. Sensing of these salinity-induced wall defects might therefore be a direct consequence of physical interaction between the extracellular domain of FER and pectin. FER-dependent signaling elicits cell-specific calcium transients that maintain cell-wall integrity during salt stress. These results reveal a novel extracellular toxicity of salinity, and identify FER as a sensor of damage to the pectin-associated wall. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  17. Pluripotency transcription factors and Tet1/2 maintain Brd4-independent stem cell identity.

    PubMed

    Finley, Lydia W S; Vardhana, Santosha A; Carey, Bryce W; Alonso-Curbelo, Direna; Koche, Richard; Chen, Yanyang; Wen, Duancheng; King, Bryan; Radler, Megan R; Rafii, Shahin; Lowe, Scott W; Allis, C David; Thompson, Craig B

    2018-05-01

    A robust network of transcription factors and an open chromatin landscape are hallmarks of the naive pluripotent state. Recently, the acetyllysine reader Brd4 has been implicated in stem cell maintenance, but the relative contribution of Brd4 to pluripotency remains unclear. Here, we show that Brd4 is dispensable for self-renewal and pluripotency of embryonic stem cells (ESCs). When maintained in their ground state, ESCs retain transcription factor binding and chromatin accessibility independent of Brd4 function or expression. In metastable ESCs, Brd4 independence can be achieved by increased expression of pluripotency transcription factors, including STAT3, Nanog or Klf4, so long as the DNA methylcytosine oxidases Tet1 and Tet2 are present. These data reveal that Brd4 is not essential for ESC self-renewal. Rather, the levels of pluripotency transcription factor abundance and Tet1/2 function determine the extent to which bromodomain recognition of protein acetylation contributes to the maintenance of gene expression and cell identity.

  18. Insulin-Like Growth Factor 1 Receptor and p38 Mitogen-Activated Protein Kinase Signals Inversely Regulate Signal Transducer and Activator of Transcription 3 Activity to Control Human Dental Pulp Stem Cell Quiescence, Propagation, and Differentiation

    PubMed Central

    Vandomme, Jerome; Touil, Yasmine; Ostyn, Pauline; Olejnik, Cecile; Flamenco, Pilar; El Machhour, Raja; Segard, Pascaline; Masselot, Bernadette; Bailliez, Yves; Formstecher, Pierre

    2014-01-01

    Dental pulp stem cells (DPSCs) remain quiescent until activated in response to severe dental pulp damage. Once activated, they exit quiescence and enter regenerative odontogenesis, producing reparative dentin. The factors and signaling molecules that control the quiescence/activation and commitment to differentiation of human DPSCs are not known. In this study, we determined that the inhibition of insulin-like growth factor 1 receptor (IGF-1R) and p38 mitogen-activated protein kinase (p38 MAPK) signaling commonly activates DPSCs and promotes their exit from the G0 phase of the cell cycle as well as from the pyronin Ylow stem cell compartment. The inhibition of these two pathways, however, inversely determines DPSC fate. In contrast to p38 MAPK inhibitors, IGF-1R inhibitors enhance dental pulp cell sphere-forming capacity and reduce the cells' colony-forming capacity without inducing cell death. The inverse cellular changes initiated by IGF-1R and p38 MAPK inhibitors were accompanied by inverse changes in the levels of active signal transducer and activator of transcription 3 (STAT3) factor, inactive glycogen synthase kinase 3, and matrix extracellular phosphoglycoprotein, a marker of early odontoblast differentiation. Our data suggest that there is cross talk between the IGF-1R and p38 MAPK signaling pathways in DPSCs and that the signals provided by these pathways converge at STAT3 and inversely regulate its activity to maintain quiescence or to promote self-renewal and differentiation of the cells. We propose a working model that explains the possible interactions between IGF-1R and p38 MAPK at the molecular level and describes the cellular consequences of these interactions. This model may inspire further fundamental study and stimulate research on the clinical applications of DPSC in cellular therapy and tissue regeneration. PMID:24266654

  19. Atg12 Maintains Skeletal Integrity by Modulating Pro-Osteoclastogenic Signals and Chondrocyte Differentiation

    NASA Technical Reports Server (NTRS)

    Tahimic, Candice; Bahl, Disha; Shirazi-Fard, Yasaman; Marsh, Timothy; Schreurs, Anne-Sofie; Rael, Victoria E.; Glikbarg, Chloe; Debnath, Jayantha; Globus, Ruth K.

    2016-01-01

    Weightlessness and radiation, two unique elements of space, profoundly decreases bone mass. This bone loss is attributed to increased activity of bone-resorbing osteoclasts and functional changes in bone-forming osteoblasts, cells that give rise to mature osteocytes. Our long-term goal is to identify signaling pathways that may be targeted to mitigate bone loss in scenarios of space exploration, radiotherapy and accidental radiation exposure. We have previously shown that exposure of MLO-Y4 osteocyte-like cells to simulated space radiation (56Fe) increased the expression of the pro-osteoclastogenic gene rankl and decreased protein levels of LC3B-II, a key player in autophagy. In this current study, we aimed to further elucidate the role of autophagy in maintaining structural integrity of the skeleton. We hypothesize that loss of autophagy in bone leads to an imbalance in pro-osteoclastogenic and pro-osteogenic signals, resulting in net bone loss. To test our hypothesis we performed global postnatal deletion of Atg12 using tamoxifeninducible Cre recombinase under the control of the CAG promoter. Six-week-old CAGCreERT2/ FloxAtg12 animals were treated daily with Tamoxifen or Vehicle (Control, oil only) for five days and euthanasia performed two weeks after the onset of treatment. Percent change in body weights (prior to treatment and at euthanasia) was not significantly different between treatment groups within the same gender. Compared to Vehicle (Control) groups, Tamoxifen (Atg12 iKO) groups showed decreased LC3B-I to II conversion and increased p62 protein levels, consistent with loss of autophagy. Quantitative PCR revealed increased expression of proosteoclastogenic cytokines mcp1 and rankl in bone and marrow respectively in male iKOs compared to male controls. Expression levels of these genes were not significantly altered in the Atg12 iKO females compared to females controls. Microcomputed tomography of tibiae revealed decreased cortical bone volume, cortical

  20. Endosomal receptor kinetics determine the stability of intracellular growth factor signalling complexes

    PubMed Central

    Tzafriri, A. Rami; Edelman, Elazer R.

    2006-01-01

    There is an emerging paradigm that growth factor signalling continues in the endosome and that cell response to a growth factor is defined by the integration of cell surface and endosomal events. As activated receptors in the endosome are exposed to a different set of binding partners, they probably elicit differential signals compared with when they are at the cell surface. As such, complete appreciation of growth factor signalling requires understanding of growth factor–receptor binding and trafficking kinetics both at the cell surface and in endosomes. Growth factor binding to surface receptors is well characterized, and endosomal binding is assumed to follow surface kinetics if one accounts for changes in pH. Yet, specific binding kinetics within the endosome has not been examined in detail. To parse the factors governing the binding state of endosomal receptors we analysed a whole-cell mathematical model of epidermal growth factor receptor trafficking and binding. We discovered that the stability of growth factor–receptor complexes within endosomes is governed by three primary independent factors: the endosomal dissociation constant, total endosomal volume and the number of endosomal receptors. These factors were combined into a single dimensionless parameter that determines the endosomal binding state of the growth factor–receptor complex and can distinguish different growth factors from each other and different cell states. Our findings indicate that growth factor binding within endosomal compartments cannot be appreciated solely on the basis of the pH-dependence of the dissociation constant and that the concentration of receptors in the endosomal compartment must also be considered. PMID:17117924

  1. Proinflammatory Cytokine Tumor Necrosis Factor (TNF)-like Weak Inducer of Apoptosis (TWEAK) Suppresses Satellite Cell Self-renewal through Inversely Modulating Notch and NF-κB Signaling Pathways*

    PubMed Central

    Ogura, Yuji; Mishra, Vivek; Hindi, Sajedah M.; Kuang, Shihuan; Kumar, Ashok

    2013-01-01

    Satellite cell self-renewal is an essential process to maintaining the robustness of skeletal muscle regenerative capacity. However, extrinsic factors that regulate self-renewal of satellite cells are not well understood. Here, we demonstrate that TWEAK cytokine reduces the proportion of Pax7+/MyoD− cells (an index of self-renewal) on myofiber explants and represses multiple components of Notch signaling in satellite cell cultures. The number of Pax7+ cells is significantly increased in skeletal muscle of TWEAK knock-out (KO) mice compared with wild-type in response to injury. Furthermore, Notch signaling is significantly elevated in cultured satellite cells and in regenerating myofibers of TWEAK-KO mice. Forced activation of Notch signaling through overexpression of the Notch1 intracellular domain (N1ICD) rescued the TWEAK-mediated inhibition of satellite cell self-renewal. TWEAK also activates the NF-κB transcription factor in satellite cells and inhibition of NF-κB significantly improved the number of Pax7+ cells in TWEAK-treated cultures. Furthermore, our results demonstrate that a reciprocal interaction between NF-κB and Notch signaling governs the inhibitory effect of TWEAK on satellite cell self-renewal. Collectively, our study demonstrates that TWEAK suppresses satellite cell self-renewal through activating NF-κB and repressing Notch signaling. PMID:24151074

  2. Proinflammatory cytokine tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) suppresses satellite cell self-renewal through inversely modulating Notch and NF-κB signaling pathways.

    PubMed

    Ogura, Yuji; Mishra, Vivek; Hindi, Sajedah M; Kuang, Shihuan; Kumar, Ashok

    2013-12-06

    Satellite cell self-renewal is an essential process to maintaining the robustness of skeletal muscle regenerative capacity. However, extrinsic factors that regulate self-renewal of satellite cells are not well understood. Here, we demonstrate that TWEAK cytokine reduces the proportion of Pax7(+)/MyoD(-) cells (an index of self-renewal) on myofiber explants and represses multiple components of Notch signaling in satellite cell cultures. The number of Pax7(+) cells is significantly increased in skeletal muscle of TWEAK knock-out (KO) mice compared with wild-type in response to injury. Furthermore, Notch signaling is significantly elevated in cultured satellite cells and in regenerating myofibers of TWEAK-KO mice. Forced activation of Notch signaling through overexpression of the Notch1 intracellular domain (N1ICD) rescued the TWEAK-mediated inhibition of satellite cell self-renewal. TWEAK also activates the NF-κB transcription factor in satellite cells and inhibition of NF-κB significantly improved the number of Pax7(+) cells in TWEAK-treated cultures. Furthermore, our results demonstrate that a reciprocal interaction between NF-κB and Notch signaling governs the inhibitory effect of TWEAK on satellite cell self-renewal. Collectively, our study demonstrates that TWEAK suppresses satellite cell self-renewal through activating NF-κB and repressing Notch signaling.

  3. A Diffusive Homeostatic Signal Maintains Neural Heterogeneity and Responsiveness in Cortical Networks

    PubMed Central

    Sweeney, Yann; Hellgren Kotaleski, Jeanette; Hennig, Matthias H.

    2015-01-01

    Gaseous neurotransmitters such as nitric oxide (NO) provide a unique and often overlooked mechanism for neurons to communicate through diffusion within a network, independent of synaptic connectivity. NO provides homeostatic control of intrinsic excitability. Here we conduct a theoretical investigation of the distinguishing roles of NO-mediated diffusive homeostasis in comparison with canonical non-diffusive homeostasis in cortical networks. We find that both forms of homeostasis provide a robust mechanism for maintaining stable activity following perturbations. However, the resulting networks differ, with diffusive homeostasis maintaining substantial heterogeneity in activity levels of individual neurons, a feature disrupted in networks with non-diffusive homeostasis. This results in networks capable of representing input heterogeneity, and linearly responding over a broader range of inputs than those undergoing non-diffusive homeostasis. We further show that these properties are preserved when homeostatic and Hebbian plasticity are combined. These results suggest a mechanism for dynamically maintaining neural heterogeneity, and expose computational advantages of non-local homeostatic processes. PMID:26158556

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sumi, Daigo, E-mail: sdaigo@ph.bunri-u.ac.j; Shinkai, Yasuhiro; Kumagai, Yoshito

    2010-05-01

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

  5. The Hedgehog Signal Induced Modulation of Bone Morphogenetic Protein Signaling: An Essential Signaling Relay for Urinary Tract Morphogenesis

    PubMed Central

    Nakagata, Naomi; Miyagawa, Shinichi; Suzuki, Kentaro; Kitazawa, Sohei; Yamada, Gen

    2012-01-01

    Background Congenital diseases of the urinary tract are frequently observed in infants. Such diseases present a number of developmental anomalies such as hydroureter and hydronephrosis. Although some genetically-modified mouse models of growth factor signaling genes reproduce urinary phenotypes, the pathogenic mechanisms remain obscure. Previous studies suggest that a portion of the cells in the external genitalia and bladder are derived from peri-cloacal mesenchymal cells that receive Hedgehog (Hh) signaling in the early developmental stages. We hypothesized that defects in such progenitor cells, which give rise to urinary tract tissues, may be a cause of such diseases. Methodology/Principal Findings To elucidate the pathogenic mechanisms of upper urinary tract malformations, we analyzed a series of Sonic hedgehog (Shh) deficient mice. Shh−/− displayed hydroureter and hydronephrosis phenotypes and reduced expression of several developmental markers. In addition, we suggested that Shh modulation at an early embryonic stage is responsible for such phenotypes by analyzing the Shh conditional mutants. Tissue contribution assays of Hh-responsive cells revealed that peri-cloacal mesenchymal cells, which received Hh signal secreted from cloacal epithelium, could contribute to the ureteral mesenchyme. Gain- and loss-of-functional mutants for Hh signaling revealed a correlation between Hh signaling and Bone morphogenetic protein (Bmp) signaling. Finally, a conditional ablation of Bmp receptor type IA (BmprIA) gene was examined in Hh-responsive cell lineages. This system thus made it possible to analyze the primary functions of the growth factor signaling relay. The defective Hh-to-Bmp signaling relay resulted in severe urinary tract phenotypes with a decrease in the number of Hh-responsive cells. Conclusions/Significance This study identified the essential embryonic stages for the pathogenesis of urinary tract phenotypes. These results suggested that Hh

  6. Application of homomorphic signal processing to stress wave factor analysis

    NASA Technical Reports Server (NTRS)

    Karagulle, H.; Williams, J. H., Jr.; Lee, S. S.

    1985-01-01

    The stress wave factor (SWF) signal, which is the output of an ultrasonic testing system where the transmitting and receiving transducers are coupled to the same face of the test structure, is analyzed in the frequency domain. The SWF signal generated in an isotropic elastic plate is modelled as the superposition of successive reflections. The reflection which is generated by the stress waves which travel p times as a longitudinal (P) wave and s times as a shear (S) wave through the plate while reflecting back and forth between the bottom and top faces of the plate is designated as the reflection with p, s. Short-time portions of the SWF signal are considered for obtaining spectral information on individual reflections. If the significant reflections are not overlapped, the short-time Fourier analysis is used. A summary of the elevant points of homomorphic signal processing, which is also called cepstrum analysis, is given. Homomorphic signal processing is applied to short-time SWF signals to obtain estimates of the log spectra of individual reflections for cases in which the reflections are overlapped. Two typical SWF signals generated in aluminum plates (overlapping and non-overlapping reflections) are analyzed.

  7. Insulin-like growth factor-1 suppresses the Myostatin signaling pathway during myogenic differentiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Retamales, A.; Zuloaga, R.; Valenzuela, C.A.

    Myogenic differentiation is a complex and well-coordinated process for generating mature skeletal muscle fibers. This event is autocrine/paracrine regulated by growth factors, principally Myostatin (MSTN) and Insulin-like Growth Factor-1 (IGF-1). Myostatin, a member of the transforming growth factor-β superfamily, is a negative regulator of skeletal muscle growth in vertebrates that exerts its inhibitory function by activating Smad transcription factors. In contrast, IGF-1 promotes the differentiation of skeletal myoblasts by activating the PI3K/Akt signaling pathway. This study reports on a novel functional crosstalk between the IGF-1 and MSTN signaling pathways, as mediated through interaction between PI3K/Akt and Smad3. Stimulation of skeletalmore » myoblasts with MSTN resulted in a transient increase in the pSmad3:Smad3 ratio and Smad-dependent transcription. Moreover, MSTN inhibited myod gene expression and myoblast fusion in an Activin receptor-like kinase/Smad3-dependent manner. Preincubation of skeletal myoblasts with IGF-1 blocked MSTN-induced Smad3 activation, promoting myod expression and myoblast differentiation. This inhibitory effect of IGF-1 on the MSTN signaling pathway was dependent on IGF-1 receptor, PI3K, and Akt activities. Finally, immunoprecipitation assay analysis determined that IGF-1 pretreatment increased Akt and Smad3 interaction. These results demonstrate that the IGF-1/PI3K/Akt pathway may inhibit MSTN signaling during myoblast differentiation, providing new insight to existing knowledge on the complex crosstalk between both growth factors. - Highlights: • IGF-1 inhibits Myostatin canonical signaling pathway through IGF-1R/PI3K/Akt pathway. • IGF-1 promotes myoblast differentiation through a direct blocking of Myostatin signaling pathway. • IGF-1 induces the interaction of Akt with Smad3 in skeletal myoblast.« less

  8. Maintaining embryonic stem cell pluripotency with Wnt signaling.

    PubMed

    Sokol, Sergei Y

    2011-10-01

    Wnt signaling pathways control lineage specification in vertebrate embryos and regulate pluripotency in embryonic stem (ES) cells, but how the balance between progenitor self-renewal and differentiation is achieved during axis specification and tissue patterning remains highly controversial. The context- and stage-specific effects of the different Wnt pathways produce complex and sometimes opposite outcomes that help to generate embryonic cell diversity. Although the results of recent studies of the Wnt/β-catenin pathway in ES cells appear to be surprising and controversial, they converge on the same conserved mechanism that leads to the inactivation of TCF3-mediated repression.

  9. Calcium Signaling in Taste Cells

    PubMed Central

    Medler, Kathryn F.

    2014-01-01

    The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. PMID:25450977

  10. Receptor Signaling Directs Global Recruitment of Pre-existing Transcription Factors to Inducible Elements.

    PubMed

    Cockerill, Peter N

    2016-12-01

    Gene expression programs are largely regulated by the tissue-specific expression of lineage-defining transcription factors or by the inducible expression of transcription factors in response to specific stimuli. Here I will review our own work over the last 20 years to show how specific activation signals also lead to the wide-spread re-distribution of pre-existing constitutive transcription factors to sites undergoing chromatin reorganization. I will summarize studies showing that activation of kinase signaling pathways creates open chromatin regions that recruit pre-existing factors which were previously unable to bind to closed chromatin. As models I will draw upon genes activated or primed by receptor signaling in memory T cells, and genes activated by cytokine receptor mutations in acute myeloid leukemia. I also summarize a hit-and-run model of stable epigenetic reprograming in memory T cells, mediated by transient Activator Protein 1 (AP-1) binding, which enables the accelerated activation of inducible enhancers.

  11. A comprehensive pathway map of epidermal growth factor receptor signaling

    PubMed Central

    Oda, Kanae; Matsuoka, Yukiko; Funahashi, Akira; Kitano, Hiroaki

    2005-01-01

    The epidermal growth factor receptor (EGFR) signaling pathway is one of the most important pathways that regulate growth, survival, proliferation, and differentiation in mammalian cells. Reflecting this importance, it is one of the best-investigated signaling systems, both experimentally and computationally, and several computational models have been developed for dynamic analysis. A map of molecular interactions of the EGFR signaling system is a valuable resource for research in this area. In this paper, we present a comprehensive pathway map of EGFR signaling and other related pathways. The map reveals that the overall architecture of the pathway is a bow-tie (or hourglass) structure with several feedback loops. The map is created using CellDesigner software that enables us to graphically represent interactions using a well-defined and consistent graphical notation, and to store it in Systems Biology Markup Language (SBML). PMID:16729045

  12. n-Iterative Exponential Forgetting Factor for EEG Signals Parameter Estimation

    PubMed Central

    Palma Orozco, Rosaura

    2018-01-01

    Electroencephalograms (EEG) signals are of interest because of their relationship with physiological activities, allowing a description of motion, speaking, or thinking. Important research has been developed to take advantage of EEG using classification or predictor algorithms based on parameters that help to describe the signal behavior. Thus, great importance should be taken to feature extraction which is complicated for the Parameter Estimation (PE)–System Identification (SI) process. When based on an average approximation, nonstationary characteristics are presented. For PE the comparison of three forms of iterative-recursive uses of the Exponential Forgetting Factor (EFF) combined with a linear function to identify a synthetic stochastic signal is presented. The one with best results seen through the functional error is applied to approximate an EEG signal for a simple classification example, showing the effectiveness of our proposal. PMID:29568310

  13. Diffusible signal factor-dependent quorum sensing in pathogenic bacteria and its exploitation for disease control.

    PubMed

    Dow, J M

    2017-01-01

    Cell-to-cell signals of the diffusible signal factor (DSF) family are cis-2-unsaturated fatty acids of differing chain length and branching pattern. DSF signalling has been described in diverse bacteria to include plant and human pathogens where it acts to regulate functions such as biofilm formation, antibiotic tolerance and the production of virulence factors. DSF family signals can also participate in interspecies signalling with other bacteria and interkingdom signalling such as with the yeast Candida albicans. Interference with DSF signalling may afford new opportunities for the control of bacterial disease. Such strategies will depend in part on detailed knowledge of the molecular mechanisms underlying the processes of signal synthesis, perception and turnover. Here, I review both recent progress in understanding DSF signalling at the molecular level and prospects for translating this knowledge into approaches for disease control. © 2016 The Society for Applied Microbiology.

  14. Environmental signals modulate ToxT-dependent virulence factor expression in Vibrio cholerae.

    PubMed

    Schuhmacher, D A; Klose, K E

    1999-03-01

    The regulatory protein ToxT directly activates the transcription of virulence factors in Vibrio cholerae, including cholera toxin (CT) and the toxin-coregulated pilus (TCP). Specific environmental signals stimulate virulence factor expression by inducing the transcription of toxT. We demonstrate that transcriptional activation by the ToxT protein is also modulated by environmental signals. ToxT expressed from an inducible promoter activated high-level expression of CT and TCP in V. cholerae at 30 degrees C, but expression of CT and TCP was significantly decreased or abolished by the addition of 0.4% bile to the medium and/or an increase of the temperature to 37 degrees C. Also, expression of six ToxT-dependent TnphoA fusions was modulated by temperature and bile. Measurement of ToxT-dependent transcription of genes encoding CT and TCP by ctxAp- and tcpAp-luciferase fusions confirmed that negative regulation by 37 degrees C or bile occurs at the transcriptional level in V. cholerae. Interestingly, ToxT-dependent transcription of these same promoters in Salmonella typhimurium was relatively insensitive to regulation by temperature or bile. These data are consistent with ToxT transcriptional activity being modulated by environmental signals in V. cholerae and demonstrate an additional level of complexity governing the expression of virulence factors in this pathogen. We propose that negative regulation of ToxT-dependent transcription by environmental signals prevents the incorrect temporal and spatial expression of virulence factors during cholera pathogenesis.

  15. WNK1 Promotes PIP2 Synthesis to Coordinate Growth Factor and GPCR-Gq Signaling

    PubMed Central

    An, Sung-Wan; Cha, Seung-Kuy; Yoon, Joonho; Chang, Seungwoo; Ross, Elliott M.; Huang, Chou-Long

    2011-01-01

    Summary Background PLC-β signaling is generally thought to be mediated by allosteric activation by G proteins and Ca2+. While availability of the PIP2 substrate is limiting in some cases, its production has not been shown to be independently regulated as a signaling mechanism. WNK1 protein kinase is known to regulate ion homeostasis and cause hypertension when expression is increased by gene mutations. However, its signaling functions remain largely elusive. Results Using diacylglycerol-stimulated TRPC6 and inositol trisphosphate-mediated Ca2+ transients as cellular biosensors, we show that WNK1 stimulates PLC-β signaling in cells by promoting the synthesis of PIP2 via stimulation of phosphatidylinositol 4-kinase IIIα. WNK1 kinase activity is not required. Stimulation of PLC-β by WNK1 and by Gαq are synergistic; WNK1 activity is essential for regulation of PLC-β signaling by Gq-coupled receptors and basal input from Gq is necessary for WNK1 signaling via PLC-β. WNK1 further amplifies PLC-β signaling when it is phosphorylated by Akt kinase in response to insulin-like growth factor. Conclusions WNK1 is a novel regulator of PLC-β that acts by controlling substrate availability. WNK1 thereby coordinates signaling between G protein and Akt kinase pathways. Because PIP2 is itself a signaling molecule, regulation of PIP2 synthesis by WNK1 also allows the cell to initiate PLC signaling while independently controlling the effects of PIP2 on other targets. These findings describe a new signaling pathway for Akt-activating growth factors, a mechanism for G protein-growth factor crosstalk and a means to independently control PLC signaling and PIP2 availability. PMID:22119528

  16. Inhibition of nuclear factor-κB signal by pyrrolidine dithiocarbamate alleviates lipopolysaccharide-induced acute lung injury

    PubMed Central

    Yang, Hongfu; Sun, Rongqing; Ma, Ning; Liu, Qilong; Sun, Xiaoge; Zi, Panpan; Wang, Junsheng; Chao, Ke; Yu, Lei

    2017-01-01

    This study mainly studied the effect of inhibition of nuclear factor-κB (NF-κB) signal by pyrrolidine dithiocarbamate (PDTC) on lipopolysaccharide (LPS)-induced inflammatory response, oxidative stress, and mitochondrial dysfunction in a murine acute lung injury model. The results showed that LPS exposure activated NF-κB and its upstream proteins and caused lung inflammation, oxidative stress, and mitochondrial dysfunction in mice. While inhibition of NF-κB by PDTC adminstration alleviated LPS-induced generation of lymphocytes, IL-1β, and TNF-α. Malondialdehyde, a common oxidative product, was markedly reduced after PDTC treatment in LPS-challenged mice. Furthermore, PDTC alleviated LPS-induced mitochondrial dysfunction via improving ATP synthesis and uncoupling protein 2 expression. In conclusion, inhibition of NF-κB by PDTC alleviated LPS-induced acute lung injury via maintaining inflammatory status, oxidative balance, and mitochondrial function in mice. PMID:28521300

  17. Fibroblast growth factor receptor signaling in kidney and lower urinary tract development.

    PubMed

    Walker, Kenneth A; Sims-Lucas, Sunder; Bates, Carlton M

    2016-06-01

    Fibroblast growth factor receptors (FGFRs) and FGF ligands are highly expressed in the developing kidney and lower urinary tract. Several classic studies showed many effects of exogenous FGF ligands on embryonic renal tissues in vitro and in vivo. Another older landmark publication showed that mice with a dominant negative Fgfr fragment had severe renal dysplasia. Together, these studies revealed the importance of FGFR signaling in kidney and lower urinary tract development. With the advent of modern gene targeting techniques, including conditional knockout approaches, several publications have revealed critical roles for FGFR signaling in many lineages of the kidney and lower urinary tract at different stages of development. FGFR signaling has been shown to be critical for early metanephric mesenchymal patterning, Wolffian duct patterning including induction of the ureteric bud, ureteric bud branching morphogenesis, nephron progenitor survival and nephrogenesis, and bladder mesenchyme patterning. FGFRs pattern these tissues by interacting with many other growth factor signaling pathways. Moreover, the many genetic Fgfr and Fgf animal models have structural defects mimicking numerous congenital anomalies of the kidney and urinary tract seen in humans. Finally, many studies have shown how FGFR signaling is critical for kidney and lower urinary tract patterning in humans.

  18. Synchronization of developmental processes and defense signaling by growth regulating transcription factors.

    PubMed

    Liu, Jinyi; Rice, J Hollis; Chen, Nana; Baum, Thomas J; Hewezi, Tarek

    2014-01-01

    Growth regulating factors (GRFs) are a conserved class of transcription factor in seed plants. GRFs are involved in various aspects of tissue differentiation and organ development. The implication of GRFs in biotic stress response has also been recently reported, suggesting a role of these transcription factors in coordinating the interaction between developmental processes and defense dynamics. However, the molecular mechanisms by which GRFs mediate the overlaps between defense signaling and developmental pathways are elusive. Here, we report large scale identification of putative target candidates of Arabidopsis GRF1 and GRF3 by comparing mRNA profiles of the grf1/grf2/grf3 triple mutant and those of the transgenic plants overexpressing miR396-resistant version of GRF1 or GRF3. We identified 1,098 and 600 genes as putative targets of GRF1 and GRF3, respectively. Functional classification of the potential target candidates revealed that GRF1 and GRF3 contribute to the regulation of various biological processes associated with defense response and disease resistance. GRF1 and GRF3 participate specifically in the regulation of defense-related transcription factors, cell-wall modifications, cytokinin biosynthesis and signaling, and secondary metabolites accumulation. GRF1 and GRF3 seem to fine-tune the crosstalk between miRNA signaling networks by regulating the expression of several miRNA target genes. In addition, our data suggest that GRF1 and GRF3 may function as negative regulators of gene expression through their association with other transcription factors. Collectively, our data provide new insights into how GRF1 and GRF3 might coordinate the interactions between defense signaling and plant growth and developmental pathways.

  19. The adaptor protein Cindr regulates JNK activity to maintain epithelial sheet integrity.

    PubMed

    Yasin, Hannah W R; van Rensburg, Samuel H; Feiler, Christina E; Johnson, Ruth I

    2016-02-15

    Epithelia are essential barrier tissues that must be appropriately maintained for their correct function. To achieve this a plethora of protein interactions regulate epithelial cell number, structure and adhesion, and differentiation. Here we show that Cindr (the Drosophila Cin85 and Cd2ap ortholog) is required to maintain epithelial integrity. Reducing Cindr triggered cell delamination and movement. Most delaminating cells died. These behaviors were consistent with JNK activation previously associated with loss of epithelial integrity in response to ectopic oncogene activity. We confirmed a novel interaction between Cindr and Drosophila JNK (dJNK), which when perturbed caused inappropriate JNK signaling. Genetically reducing JNK signaling activity suppressed the effects of reducing Cindr. Furthermore, ectopic JNK signaling phenocopied loss of Cindr and was partially rescued by concomitant cindr over-expression. Thus, correct Cindr-dJNK stoichiometry is essential to maintain epithelial integrity and disturbing this balance may contribute to the pathogenesis of disease states, including cancer. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Heat shock factor-1 intertwines insulin/IGF-1, TGF-β and cGMP signaling to control development and aging.

    PubMed

    Barna, János; Princz, Andrea; Kosztelnik, Mónika; Hargitai, Balázs; Takács-Vellai, Krisztina; Vellai, Tibor

    2012-11-01

    Temperature affects virtually all cellular processes. A quick increase in temperature challenges the cells to undergo a heat shock response to maintain cellular homeostasis. Heat shock factor-1 (HSF-1) functions as a major player in this response as it activates the transcription of genes coding for molecular chaperones (also called heat shock proteins) that maintain structural integrity of proteins. However, the mechanisms by which HSF-1 adjusts fundamental cellular processes such as growth, proliferation, differentiation and aging to the ambient temperature remain largely unknown. We demonstrate here that in Caenorhabditis elegans HSF-1 represses the expression of daf-7 encoding a TGF-β (transforming growth factor-beta) ligand, to induce young larvae to enter the dauer stage, a developmentally arrested, non-feeding, highly stress-resistant, long-lived larval form triggered by crowding and starvation. Under favorable conditions, HSF-1 is inhibited by crowding pheromone-sensitive guanylate cyclase/cGMP (cyclic guanosine monophosphate) and systemic nutrient-sensing insulin/IGF-1 (insulin-like growth factor-1) signaling; loss of HSF-1 activity allows DAF-7 to promote reproductive growth. Thus, HSF-1 interconnects the insulin/IGF-1, TGF-β and cGMP neuroendocrine systems to control development and longevity in response to diverse environmental stimuli. Furthermore, HSF-1 upregulates another TGF-β pathway-interacting gene, daf-9/cytochrome P450, thereby fine-tuning the decision between normal growth and dauer formation. Together, these results provide mechanistic insight into how temperature, nutrient availability and population density coordinately influence development, lifespan, behavior and stress response through HSF-1.

  1. Functional roles of fibroblast growth factor receptors (FGFRs) signaling in human cancers.

    PubMed

    Tiong, Kai Hung; Mah, Li Yen; Leong, Chee-Onn

    2013-12-01

    The fibroblast growth factor receptors (FGFRs) regulate important biological processes including cell proliferation and differentiation during development and tissue repair. Over the past decades, numerous pathological conditions and developmental syndromes have emerged as a consequence of deregulation in the FGFRs signaling network. This review aims to provide an overview of FGFR family, their complex signaling pathways in tumorigenesis, and the current development and application of therapeutics targeting the FGFRs signaling for treatment of refractory human cancers.

  2. MAPK signaling promotes axonal degeneration by speeding the turnover of the axonal maintenance factor NMNAT2

    PubMed Central

    Walker, Lauren J; Summers, Daniel W; Sasaki, Yo; Brace, EJ; Milbrandt, Jeffrey; DiAntonio, Aaron

    2017-01-01

    Injury-induced (Wallerian) axonal degeneration is regulated via the opposing actions of pro-degenerative factors such as SARM1 and a MAPK signal and pro-survival factors, the most important of which is the NAD+ biosynthetic enzyme NMNAT2 that inhibits activation of the SARM1 pathway. Here we investigate the mechanism by which MAPK signaling facilitates axonal degeneration. We show that MAPK signaling promotes the turnover of the axonal survival factor NMNAT2 in cultured mammalian neurons as well as the Drosophila ortholog dNMNAT in motoneurons. The increased levels of NMNAT2 are required for the axonal protection caused by loss of MAPK signaling. Regulation of NMNAT2 by MAPK signaling does not require SARM1, and so cannot be downstream of SARM1. Hence, pro-degenerative MAPK signaling functions upstream of SARM1 by limiting the levels of the essential axonal survival factor NMNAT2 to promote injury-dependent SARM1 activation. These findings are consistent with a linear molecular pathway for the axonal degeneration program. DOI: http://dx.doi.org/10.7554/eLife.22540.001 PMID:28095293

  3. Retrograde Signaling as a Mechanism of Yeast Adaptation to Unfavorable Factors.

    PubMed

    Trendeleva, T A; Zvyagilskaya, R A

    2018-02-01

    Mitochondria perform many essential functions in eukaryotic cells. Being the main producers of ATP and the site of many catabolic and anabolic reactions, they participate in intracellular signaling, proliferation, aging, and formation of reactive oxygen species. Mitochondrial dysfunction is the cause of many diseases and even cell death. The functioning of mitochondria in vivo is impossible without interaction with other cellular compartments. Mitochondrial retrograde signaling is a signaling pathway connecting mitochondria and the nucleus. The major signal transducers in the yeast retrograde response are Rtg1p, Rtg2p, and Rtg3p proteins, as well as four additional negative regulatory factors - Mks1p, Lst8p, and two 14-3-3 proteins (Bmh1/2p). In this review, we analyze current information on the retrograde signaling in yeast that is regarded as a stress or homeostatic response mechanism to changes in various metabolic and biosynthetic activities that occur upon mitochondrial dysfunction. We also discuss relations between retrograde signaling and other signaling pathways in the cell.

  4. Evaluating the impact of grade crossing safety factors through signal detection theory

    DOT National Transportation Integrated Search

    2012-10-22

    The purpose of this effort was to apply signal detection theory to descriptively model the impact : of five grade crossing safety factors to understand their effect on driver decision making. The : safety factors consisted of: improving commercial mo...

  5. Fibroblast growth factor receptor signaling as therapeutic targets in gastric cancer

    PubMed Central

    Yashiro, Masakazu; Matsuoka, Tasuku

    2016-01-01

    Fibroblast growth factor receptors (FGFRs) regulate a variety of cellular functions, from embryogenesis to adult tissue homeostasis. FGFR signaling also plays significant roles in the proliferation, invasion, and survival of several types of tumor cells. FGFR-induced alterations, including gene amplification, chromosomal translocation, and mutations, have been shown to be associated with the tumor initiation and progression of gastric cancer, especially in diffuse-type cancers. Therefore, the FGFR signaling pathway might be one of the therapeutic targets in gastric cancer. This review aims to provide an overview of the role of FGFR signaling in tumorigenesis, tumor progression, proliferation, and chemoresistance. We also discuss the accumulating evidence that demonstrates the effectiveness of using clinical therapeutic agents to inhibit FGFR signaling for the treatment of gastric cancer. PMID:26937130

  6. Fibroblast growth factor receptor signaling as therapeutic targets in gastric cancer.

    PubMed

    Yashiro, Masakazu; Matsuoka, Tasuku

    2016-02-28

    Fibroblast growth factor receptors (FGFRs) regulate a variety of cellular functions, from embryogenesis to adult tissue homeostasis. FGFR signaling also plays significant roles in the proliferation, invasion, and survival of several types of tumor cells. FGFR-induced alterations, including gene amplification, chromosomal translocation, and mutations, have been shown to be associated with the tumor initiation and progression of gastric cancer, especially in diffuse-type cancers. Therefore, the FGFR signaling pathway might be one of the therapeutic targets in gastric cancer. This review aims to provide an overview of the role of FGFR signaling in tumorigenesis, tumor progression, proliferation, and chemoresistance. We also discuss the accumulating evidence that demonstrates the effectiveness of using clinical therapeutic agents to inhibit FGFR signaling for the treatment of gastric cancer.

  7. Insulin-Like Growth Factor and Epidermal Growth Factor Signaling in Breast Cancer Cell Growth: Focus on Endocrine Resistant Disease

    PubMed Central

    Berdiaki, Aikaterini; Tzardi, Maria

    2015-01-01

    Breast cancer is the most common type of cancer for women worldwide with a lifetime risk amounting to a staggering total of 10%. It is well established that the endogenous synthesis of insulin-like growth factor (IGF) and epidermal growth factor (EGF) polypeptide growth factors are closely correlated to malignant transformation and all the steps of the breast cancer metastatic cascade. Numerous studies have demonstrated that both estrogens and growth factors stimulate the proliferation of steroid-dependent tumor cells, and that the interaction between these signaling pathways occurs at several levels. Importantly, the majority of breast cancer cases are estrogen receptor- (ER-) positive which have a more favorable prognosis and pattern of recurrence with endocrine therapy being the backbone of treatment. Unfortunately, the majority of patients progress to endocrine therapy resistant disease (acquired resistance) whereas a proportion of patients may fail to respond to initial therapy (de novo resistance). The IGF-I and EGF downstream signaling pathways are closely involved in the process of progression to therapy resistant disease. Modifications in the bioavailability of these growth factors contribute critically to disease progression. In the present review therefore, we will discuss in depth how IGF and EGF signaling participate in breast cancer pathogenesis and progression to endocrine resistant disease. PMID:26258011

  8. Fibroblast growth factor receptor-Frs2α signaling is critical for nephron progenitors.

    PubMed

    Di Giovanni, Valeria; Walker, Kenneth A; Bushnell, Daniel; Schaefer, Caitlin; Sims-Lucas, Sunder; Puri, Pawan; Bates, Carlton M

    2015-04-01

    Previous studies using transgenic Pax3cre mice have revealed roles for fibroblast growth factor receptors (Fgfrs) and Fgfr substrate 2α (Frs2α) signaling in early metanephric mesenchyme patterning and in ureteric morphogenesis. The role of Fgfr/Frs2α signaling in nephron progenitors is unknown. Thus, we generated mouse models using BAC transgenic Six2EGFPcre (Six2cre) mediated deletion of Fgfrs and/or Frs2α in nephron progenitors. Six2cre mediated deletion of Fgfr1 or Fgfr2 alone led to no obvious kidney defects. Six2creFgfr1(flox/flox)Fgfr2(flox/flox) (Fgfr1/2(NP-/-)) mice generate a discernable kidney; however, they develop nephron progenitor depletion starting at embryonic day 12.5 (E12.5) and later demonstrate severe cystic dysplasia. To determine the role of Frs2α signaling downstream of Fgfr2 in Fgfr1/2(NP-/-) mice, we generated Six2cre(,)Fgfr1(flox/flox)Fgfr2(LR/LR) (Fgfr1(NP-/-)Fgfr2(LR/LR)) mice that have point mutations in the Frs2α binding site of Fgfr2. Like Fgfr1/2(NP-/-) mice, Fgfr1(NP-/-)Fgfr2(LR/LR) develop nephron progenitor depletion, but it does not start until E14.5 and older mice have less severe cystic dysplasia than Fgfr1/2(NP-/-) To determine the role of Frs2α alone in nephron progenitors, we generated Six2creFrs2'A(flox/flox) (Frs2a(NP-/-)) mice. Frs2a(NP-/-)mice also develop nephron progenitor depletion and renal cysts, although these occurred later and were less severe than in the other Six2cre mutant mice. The nephron progenitor loss in all Six2cre mutant lines was associated with decreased Cited1 expression and increased apoptosis versus controls. FAC-sorted nephron progenitors in Six2cre Frs2'A(flox/flox) mice demonstrated evidence of increased Notch activity versus controls, which likely drives the progenitor defects. Thus, Fgfr1 and Fgfr2 have synergistic roles in maintaining nephron progenitors; furthermore, Fgfr signaling in nephron progenitors appears to be mediated predominantly by Frs2α. Copyright © 2015 Elsevier Inc

  9. Vascular Endothelial Growth Factor (VEGF) and Platelet (PF-4) Factor 4 Inputs Modulate Human Microvascular Endothelial Signaling in a Three-Dimensional Matrix Migration Context*

    PubMed Central

    Hang, Ta-Chun; Tedford, Nathan C.; Reddy, Raven J.; Rimchala, Tharathorn; Wells, Alan; White, Forest M.; Kamm, Roger D.; Lauffenburger, Douglas A.

    2013-01-01

    The process of angiogenesis is under complex regulation in adult organisms, particularly as it often occurs in an inflammatory post-wound environment. As such, there are many impacting factors that will regulate the generation of new blood vessels which include not only pro-angiogenic growth factors such as vascular endothelial growth factor, but also angiostatic factors. During initial postwound hemostasis, a large initial bolus of platelet factor 4 is released into localized areas of damage before progression of wound healing toward tissue homeostasis. Because of its early presence and high concentration, the angiostatic chemokine platelet factor 4, which can induce endothelial anoikis, can strongly affect angiogenesis. In our work, we explored signaling crosstalk interactions between vascular endothelial growth factor and platelet factor 4 using phosphotyrosine-enriched mass spectrometry methods on human dermal microvascular endothelial cells cultured under conditions facilitating migratory sprouting into collagen gel matrices. We developed new methods to enable mass spectrometry-based phosphorylation analysis of primary cells cultured on collagen gels, and quantified signaling pathways over the first 48 h of treatment with vascular endothelial growth factor in the presence or absence of platelet factor 4. By observing early and late signaling dynamics in tandem with correlation network modeling, we found that platelet factor 4 has significant crosstalk with vascular endothelial growth factor by modulating cell migration and polarization pathways, centered around P38α MAPK, Src family kinases Fyn and Lyn, along with FAK. Interestingly, we found EphA2 correlational topology to strongly involve key migration-related signaling nodes after introduction of platelet factor 4, indicating an influence of the angiostatic factor on this ambiguous but generally angiogenic signal in this complex environment. PMID:24023389

  10. Basal Immunoglobulin Signaling Actively Maintains Developmental Stage in Immature B Cells

    PubMed Central

    Tze, Lina E; Schram, Brian R; Lam, Kong-Peng; Hogquist, Kristin A; Hippen, Keli L; Liu, Jiabin; Shinton, Susan A; Otipoby, Kevin L; Rodine, Peter R; Vegoe, Amanda L; Kraus, Manfred; Hardy, Richard R; Schlissel, Mark S; Rajewsky, Klaus

    2005-01-01

    In developing B lymphocytes, a successful V(D)J heavy chain (HC) immunoglobulin (Ig) rearrangement establishes HC allelic exclusion and signals pro-B cells to advance in development to the pre-B stage. A subsequent functional light chain (LC) rearrangement then results in the surface expression of IgM at the immature B cell stage. Here we show that interruption of basal IgM signaling in immature B cells, either by the inducible deletion of surface Ig via Cre-mediated excision or by incubating cells with the tyrosine kinase inhibitor herbimycin A or the phosphatidylinositol 3-kinase inhibitor wortmannin, led to a striking “back-differentiation” of cells to an earlier stage in B cell development, characterized by the expression of pro-B cell genes. Cells undergoing this reversal in development also showed evidence of new LC gene rearrangements, suggesting an important role for basal Ig signaling in the maintenance of LC allelic exclusion. These studies identify a previously unappreciated level of plasticity in the B cell developmental program, and have important implications for our understanding of central tolerance mechanisms. PMID:15752064

  11. Cross-talk between GPER and growth factor signaling.

    PubMed

    Lappano, Rosamaria; De Marco, Paola; De Francesco, Ernestina Marianna; Chimento, Adele; Pezzi, Vincenzo; Maggiolini, Marcello

    2013-09-01

    G protein-coupled receptors (GPCRs) and growth factor receptors mediate multiple physio-pathological responses to a diverse array of extracellular stimuli. In this regard, it has been largely demonstrated that GPCRs and growth factor receptors generate a multifaceted signaling network, which triggers relevant biological effects in normal and cancer cells. For instance, some GPCRs transactivate the epidermal growth factor receptor (EGFR), which stimulates diverse transduction pathways leading to gene expression changes, cell migration, survival and proliferation. Moreover, it has been reported that a functional interaction between growth factor receptors and steroid hormones like estrogens is involved in the growth of many types of tumors as well as in the resistance to endocrine therapy. This review highlights recent findings on the cross-talk between a member of the GPCR family, the G protein-coupled estrogen receptor 1 (GPER, formerly known as GPR30) and two main growth factor receptors like EGFR and insulin-like growth factor-I receptor (IGF-IR). The biological implications of the functional interaction between these important mediators of cell responses particularly in cancer are discussed. This article is part of a Special Issue entitled 'CSR 2013'. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. A Class I ADP-Ribosylation Factor GTPase-Activating Protein Is Critical for Maintaining Directional Root Hair Growth in Arabidopsis1[W][OA

    PubMed Central

    Yoo, Cheol-Min; Wen, Jiangqi; Motes, Christy M.; Sparks, J. Alan; Blancaflor, Elison B.

    2008-01-01

    Membrane trafficking and cytoskeletal dynamics are important cellular processes that drive tip growth in root hairs. These processes interact with a multitude of signaling pathways that allow for the efficient transfer of information to specify the direction in which tip growth occurs. Here, we show that AGD1, a class I ADP ribosylation factor GTPase-activating protein, is important for maintaining straight growth in Arabidopsis (Arabidopsis thaliana) root hairs, since mutations in the AGD1 gene resulted in wavy root hair growth. Live cell imaging of growing agd1 root hairs revealed bundles of endoplasmic microtubules and actin filaments extending into the extreme tip. The wavy phenotype and pattern of cytoskeletal distribution in root hairs of agd1 partially resembled that of mutants in an armadillo repeat-containing kinesin (ARK1). Root hairs of double agd1 ark1 mutants were more severely deformed compared with single mutants. Organelle trafficking as revealed by a fluorescent Golgi marker was slightly inhibited, and Golgi stacks frequently protruded into the extreme root hair apex of agd1 mutants. Transient expression of green fluorescent protein-AGD1 in tobacco (Nicotiana tabacum) epidermal cells labeled punctate bodies that partially colocalized with the endocytic marker FM4-64, while ARK1-yellow fluorescent protein associated with microtubules. Brefeldin A rescued the phenotype of agd1, indicating that the altered activity of an AGD1-dependent ADP ribosylation factor contributes to the defective growth, organelle trafficking, and cytoskeletal organization of agd1 root hairs. We propose that AGD1, a regulator of membrane trafficking, and ARK1, a microtubule motor, are components of converging signaling pathways that affect cytoskeletal organization to specify growth orientation in Arabidopsis root hairs. PMID:18539780

  13. Fibroblast growth factor receptor signaling in kidney and lower urinary tract development

    PubMed Central

    Walker, Kenneth A; Sims-Lucas, Sunder; Bates, Carlton M.

    2015-01-01

    Fibroblast growth factor receptors (FGFRs) and FGF ligands are highly expressed in the developing kidney and lower urinary tract. Several classic studies showed many effects of exogenous FGF ligands on embryonic renal tissues in vitro and in vivo. Another older landmark publication showed that mice with a dominant negative Fgfr fragment had severe renal dysplasia. Together these studies revealed the importance of FGFR signaling in kidney and lower urinary tract development. With the advent of modern gene targeting techniques, including conditional knockout approaches, several publications have revealed critical roles for FGFR signaling in many lineages of the kidney and lower urinary tract at different stages of development. FGFR signaling has been shown to be critical for early metanephric mesenchymal patterning, Wolffian duct patterning including induction of the ureteric bud, ureteric bud branching morphogenesis, nephron progenitor survival and nephrogenesis, and bladder mesenchyme patterning. FGFRs pattern these tissues by interacting with many other growth factor signaling pathways. Moreover, the many genetic Fgfr and Fgf animal models have structural defects mimicking numerous congenital anomalies of the kidney and urinary tract seen in humans. Finally, many studies have shown how FGFR signaling is critical for kidney and lower urinary tract patterning in humans. PMID:26293980

  14. Identification of regional activation by factorization of high-density surface EMG signals: A comparison of Principal Component Analysis and Non-negative Matrix factorization.

    PubMed

    Gallina, Alessio; Garland, S Jayne; Wakeling, James M

    2018-05-22

    In this study, we investigated whether principal component analysis (PCA) and non-negative matrix factorization (NMF) perform similarly for the identification of regional activation within the human vastus medialis. EMG signals from 64 locations over the VM were collected from twelve participants while performing a low-force isometric knee extension. The envelope of the EMG signal of each channel was calculated by low-pass filtering (8 Hz) the monopolar EMG signal after rectification. The data matrix was factorized using PCA and NMF, and up to 5 factors were considered for each algorithm. Association between explained variance, spatial weights and temporal scores between the two algorithms were compared using Pearson correlation. For both PCA and NMF, a single factor explained approximately 70% of the variance of the signal, while two and three factors explained just over 85% or 90%. The variance explained by PCA and NMF was highly comparable (R > 0.99). Spatial weights and temporal scores extracted with non-negative reconstruction of PCA and NMF were highly associated (all p < 0.001, mean R > 0.97). Regional VM activation can be identified using high-density surface EMG and factorization algorithms. Regional activation explains up to 30% of the variance of the signal, as identified through both PCA and NMF. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Contributory factors to traffic crashes at signalized intersections in Hong Kong.

    PubMed

    Wong, S C; Sze, N N; Li, Y C

    2007-11-01

    Efficient geometric design and signal timing not only improve operational performance at signalized intersections by expanding capacity and reducing traffic delays, but also result in an appreciable reduction in traffic conflicts, and thus better road safety. Information on the incidence of crashes, traffic flow, geometric design, road environment, and traffic control at 262 signalized intersections in Hong Kong during 2002 and 2003 are incorporated into a crash prediction model. Poisson regression and negative binomial regression are used to quantify the influence of possible contributory factors on the incidence of killed and severe injury (KSI) crashes and slight injury crashes, respectively, while possible interventions by traffic flow are controlled. The results for the incidence of slight injury crashes reveal that the road environment, degree of curvature, and presence of tram stops are significant factors, and that traffic volume has a diminishing effect on the crash risk. The presence of tram stops, number of pedestrian streams, road environment, proportion of commercial vehicles, average lane width, and degree of curvature increase the risk of KSI crashes, but the effect of traffic volume is negligible.

  16. Role of fibroblast growth factor receptor signaling in kidney development.

    PubMed

    Bates, Carlton M

    2011-09-01

    Fibroblast growth factor receptors (Fgfrs) are expressed throughout the developing kidney. Several early studies have shown that exogenous fibroblast growth factors (Fgfs) affect growth and maturation of the metanephric mesenchyme (MM) and ureteric bud (UB). Transgenic mice that over-express a dominant negative receptor isoform develop renal aplasia/severe dysplasia, confirming the importance of Fgfrs in renal development. Furthermore, global deletion of Fgf7, Fgf10, and Fgfr2IIIb (isoform that binds Fgf7 and Fgf10) in mice leads to small kidneys with fewer collecting ducts and nephrons. Deletion of Fgfrl1, a receptor lacking intracellular signaling domains, causes severe renal dysgenesis. Conditional targeting of Fgf8 from the MM interrupts nephron formation. Deletion of Fgfr2 from the UB results in severe ureteric branching and stromal mesenchymal defects, although loss of Frs2α (major signaling adapter for Fgfrs) in the UB causes only mild renal hypoplasia. Deletion of both Fgfr1 and Fgfr2 in the MM results in renal aplasia with defects in MM formation and initial UB elongation and branching. Loss of Fgfr2 in the MM leads to many renal and urinary tract anomalies as well as vesicoureteral reflux. Thus, Fgfr signaling is critical for patterning of virtually all renal lineages at early and later stages of development.

  17. Involvement of nuclear factor κB in platelet CD40 signaling.

    PubMed

    Hachem, Ahmed; Yacoub, Daniel; Zaid, Younes; Mourad, Walid; Merhi, Yahye

    2012-08-17

    CD40 ligand (CD40L) is a thrombo-inflammatory molecule that predicts cardiovascular events. Platelets constitute the major source of soluble CD40L (sCD40L), which has been shown to potentiate platelet activation and aggregation, in a CD40-dependent manner, via p38 mitogen activated protein kinase (MAPK) and Rac1 signaling. In many cells, the CD40L/CD40 dyad also induces activation of nuclear factor kappa B (NF-κB). Given that platelets contain NF-κB, we hypothesized that it may be involved in platelet CD40 signaling and function. In human platelets, sCD40L induces association of CD40 with its adaptor protein the tumor necrosis factor receptor associated factor 2 and triggers phosphorylation of IκBα, which are abolished by CD40L blockade. Inhibition of IκBα phosphorylation reverses sCD40L-induced IκBα phosphorylation without affecting p38 MAPK phosphorylation. On the other hand, inhibition of p38 MAPK phosphorylation has no effect on IκBα phosphorylation, indicating a divergence in the signaling pathway originating from CD40 upon its ligation. In functional studies, inhibition of IκBα phosphorylation reverses sCD40L-induced platelet activation and potentiation of platelet aggregation in response to a sub-threshold concentration of collagen. This study demonstrates that the sCD40L/CD40 axis triggers NF-κB activation in platelets. This signaling pathway plays a critical role in platelet activation and aggregation upon sCD40L stimulation and may represent an important target against thrombo-inflammatory disorders. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. An engineered transforming growth factor β (TGF-β) monomer that functions as a dominant negative to block TGF-β signaling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, Sun Kyung; Barron, Lindsey; Hinck, Cynthia S.

    The transforming growth factor β isoforms, TGF-β1, -β2, and -β3, are small secreted homodimeric signaling proteins with essential roles in regulating the adaptive immune system and maintaining the extracellular matrix. However, dysregulation of the TGF-β pathway is responsible for promoting the progression of several human diseases, including cancer and fibrosis. Despite the known importance of TGF-βs in promoting disease progression, no inhibitors have been approved for use in humans. Herein, we describe an engineered TGF-β monomer, lacking the heel helix, a structural motif essential for binding the TGF-β type I receptor (TβRI) but dispensable for binding the other receptor requiredmore » for TGF-β signaling, the TGF-β type II receptor (TβRII), as an alternative therapeutic modality for blocking TGF-β signaling in humans. As shown through binding studies and crystallography, the engineered monomer retained the same overall structure of native TGF-β monomers and bound TβRII in an identical manner. Cell-based luciferase assays showed that the engineered monomer functioned as a dominant negative to inhibit TGF-β signaling with a Ki of 20–70 nM. Investigation of the mechanism showed that the high affinity of the engineered monomer for TβRII, coupled with its reduced ability to non-covalently dimerize and its inability to bind and recruit TβRI, enabled it to bind endogenous TβRII but prevented it from binding and recruiting TβRI to form a signaling complex. Such engineered monomers provide a new avenue to probe and manipulate TGF-β signaling and may inform similar modifications of other TGF-β family members.« less

  19. The Crossroads of Synaptic Growth Signaling, Membrane Traffic and Neurological Disease: Insights from Drosophila.

    PubMed

    Deshpande, Mugdha; Rodal, Avital A

    2016-02-01

    Neurons require target-derived autocrine and paracrine growth factors to maintain proper identity, innervation, homeostasis and survival. Neuronal growth factor signaling is highly dependent on membrane traffic, both for the packaging and release of the growth factors themselves, and for regulation of intracellular signaling by their transmembrane receptors. Here, we review recent findings from the Drosophila larval neuromuscular junction (NMJ) that illustrate how specific steps of intracellular traffic and inter-organelle interactions impinge on signaling, particularly in the bone morphogenic protein, Wingless and c-Jun-activated kinase pathways, regulating elaboration and stability of NMJ arbors, construction of synapses and synaptic transmission and homeostasis. These membrane trafficking and signaling pathways have been implicated in human motor neuron diseases including amyotrophic lateral sclerosis and hereditary spastic paraplegia, highlighting their importance for neuronal health and survival. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Regulation of pancreatic islet beta-cell mass by growth factor and hormone signaling.

    PubMed

    Huang, Yao; Chang, Yongchang

    2014-01-01

    Dysfunction and destruction of pancreatic islet beta cells is a hallmark of diabetes. Better understanding of cellular signals in beta cells will allow development of therapeutic strategies for diabetes, such as preservation and expansion of beta-cell mass and improvement of beta-cell function. During the past several decades, the number of studies analyzing the molecular mechanisms, including growth factor/hormone signaling pathways that impact islet beta-cell mass and function, has increased exponentially. Notably, somatolactogenic hormones including growth hormone (GH), prolactin (PRL), and insulin-like growth factor-1 (IGF-1) and their receptors (GHR, PRLR, and IGF-1R) are critically involved in beta-cell growth, survival, differentiation, and insulin secretion. In this chapter, we focus more narrowly on GH, PRL, and IGF-1 signaling, and GH-IGF-1 cross talk. We also discuss how these signaling aspects contribute to the regulation of beta-cell proliferation and apoptosis. In particular, our novel findings of GH-induced formation of GHR-JAK2-IGF-1R protein complex and synergistic effects of GH and IGF-1 on beta-cell signaling, proliferation, and antiapoptosis lead to a new concept that IGF-1R may serve as a proximal component of GH/GHR signaling. © 2014 Elsevier Inc. All rights reserved.

  1. Characterization of a Diffusible Signaling Factor from Xylella fastidiosa

    PubMed Central

    Beaulieu, Ellen D.; Ionescu, Michael; Chatterjee, Subhadeep; Yokota, Kenji; Trauner, Dirk; Lindow, Steven

    2013-01-01

    ABSTRACT Cell-cell signaling in Xylella fastidiosa has been implicated in the coordination of traits enabling colonization in plant hosts as well as insect vectors. This cell density-dependent signaling has been attributed to a diffusible signaling factor (DSF) produced by the DSF synthase RpfF. DSF produced by related bacterial species are unsaturated fatty acids, but that of X. fastidiosa was thought to be different from those of other taxa. We describe here the isolation and characterization of an X. fastidiosa DSF (XfDSF) as 2(Z)-tetradecenoic acid. This compound was isolated both from recombinant Erwinia herbicola expressing X. fastidiosa rpfF and from an X. fastidiosa rpfC deletion mutant that overproduces DSF. Since an rpfF mutant is impaired in biofilm formation and underexpresses the hemagglutinin-like protein-encoding genes hxfA and hxfB, we demonstrate that these traits can be restored by ca. 0.5 µM XfDSF but not by myristic acid, the fully saturated tetradecenoic acid. A phoA-based X. fastidiosa biosensor that assesses DSF-dependent expression of hxfA or hxfB revealed a high level of molecular specificity of DSF signaling. PMID:23300249

  2. Involvement of epidermal growth factor receptor signaling in estrogen inhibition of oocyte maturation mediated through the G protein-coupled estrogen receptor (Gper) in zebrafish (Danio rerio).

    PubMed

    Peyton, Candace; Thomas, Peter

    2011-07-01

    Oocyte maturation (OM) in teleosts is under precise hormonal control by progestins and estrogens. We show here that estrogens activate an epidermal growth factor receptor (Egfr) signaling pathway in fully grown, denuded zebrafish (Danio rerio) oocytes through the G protein-coupled estrogen receptor (Gper; also known as GPR30) to maintain oocyte meiotic arrest in a germinal vesicle breakdown (GVBD) bioassay. A GPER-specific antagonist, G-15, increased spontaneous OM, indicating that the inhibitory estrogen actions on OM are mediated through Gper. Estradiol-17beta-bovine serum albumin, which cannot enter oocytes, decreased GVBD, whereas treatment with actinomycin D did not block estrogen's inhibitory effects, suggesting that estrogens act at the cell surface via a nongenomic mechanism to prevent OM. The intracellular tyrosine kinase (Src) inhibitor, PP2, blocked estrogen inhibition of OM. Expression of egfr mRNA and Egfr protein were detected in denuded zebrafish oocytes. The matrix metalloproteinase (MMP) inhibitor, ilomastat, which prevents the release of heparin-bound epidermal growth factor, increased spontaneous OM, whereas the MMP activator, interleukin-1alpha, decreased spontaneous OM. Moreover, inhibitors of EGFR (ErbB1) and extracellular-related kinase 1 and 2 (Erk1/2; official symbol Mapk3/1) increased spontaneous OM. In addition, estradiol-17beta and the GPER agonist, G-1, increased phosphorylation of Erk, and this was abrogated by simultaneous treatment with the EGFR inhibitor. Taken together, these results suggest that estrogens act through Gper to maintain meiotic arrest via an Src kinase-dependent G-protein betagamma subunit signaling pathway involving transactivation of egfr and phosphorylation of Mapk3/1. To our knowledge, this is the first evidence that EGFR signaling in vertebrate oocytes can prevent meiotic progression.

  3. Genetic Analysis of Fibroblast Growth Factor Signaling in the Drosophila Eye

    PubMed Central

    Mukherjee, T.; Choi, I.; Banerjee, Utpal

    2012-01-01

    The development of eyes in Drosophila involves intricate epithelial reorganization events for accurate positioning of cells and proper formation and organization of ommatidial clusters. We demonstrate that Branchless (Bnl), the fibroblast growth factor ligand, regulates restructuring events in the eye disc primordium from as early as the emergence of clusters from a morphogenetic front to the cellular movements during pupal eye development. Breathless (Btl) functions as the fibroblast growth factor receptor to mediate Bnl signal, and together they regulate expression of DE-cadherin, Crumbs, and Actin. In addition, in the eye Bnl regulates the temporal onset and extent of retinal basal glial cell migration by activating Btl in the glia. We hypothesized that the Bnl functions in the eye are Hedgehog dependent and represent novel aspects of Bnl signaling not explored previously. PMID:22384378

  4. Genetic analysis of fibroblast growth factor signaling in the Drosophila eye.

    PubMed

    Mukherjee, T; Choi, I; Banerjee, Utpal

    2012-01-01

    The development of eyes in Drosophila involves intricate epithelial reorganization events for accurate positioning of cells and proper formation and organization of ommatidial clusters. We demonstrate that Branchless (Bnl), the fibroblast growth factor ligand, regulates restructuring events in the eye disc primordium from as early as the emergence of clusters from a morphogenetic front to the cellular movements during pupal eye development. Breathless (Btl) functions as the fibroblast growth factor receptor to mediate Bnl signal, and together they regulate expression of DE-cadherin, Crumbs, and Actin. In addition, in the eye Bnl regulates the temporal onset and extent of retinal basal glial cell migration by activating Btl in the glia. We hypothesized that the Bnl functions in the eye are Hedgehog dependent and represent novel aspects of Bnl signaling not explored previously.

  5. Intrinsic noise analysis and stochastic simulation on transforming growth factor beta signal pathway

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Ouyang, Qi

    2010-10-01

    A typical biological cell lives in a small volume at room temperature; the noise effect on the cell signal transduction pathway may play an important role in its dynamics. Here, using the transforming growth factorsignal transduction pathway as an example, we report our stochastic simulations of the dynamics of the pathway and introduce a linear noise approximation method to calculate the transient intrinsic noise of pathway components. We compare the numerical solutions of the linear noise approximation with the statistic results of chemical Langevin equations, and find that they are quantitatively in agreement with the other. When transforming growth factor-β dose decreases to a low level, the time evolution of noise fluctuation of nuclear Smad2—Smad4 complex indicates the abnormal enhancement in the transient signal activation process.

  6. Nonnegative Matrix Factorization for identification of unknown number of sources emitting delayed signals

    PubMed Central

    Iliev, Filip L.; Stanev, Valentin G.; Vesselinov, Velimir V.

    2018-01-01

    Factor analysis is broadly used as a powerful unsupervised machine learning tool for reconstruction of hidden features in recorded mixtures of signals. In the case of a linear approximation, the mixtures can be decomposed by a variety of model-free Blind Source Separation (BSS) algorithms. Most of the available BSS algorithms consider an instantaneous mixing of signals, while the case when the mixtures are linear combinations of signals with delays is less explored. Especially difficult is the case when the number of sources of the signals with delays is unknown and has to be determined from the data as well. To address this problem, in this paper, we present a new method based on Nonnegative Matrix Factorization (NMF) that is capable of identifying: (a) the unknown number of the sources, (b) the delays and speed of propagation of the signals, and (c) the locations of the sources. Our method can be used to decompose records of mixtures of signals with delays emitted by an unknown number of sources in a nondispersive medium, based only on recorded data. This is the case, for example, when electromagnetic signals from multiple antennas are received asynchronously; or mixtures of acoustic or seismic signals recorded by sensors located at different positions; or when a shift in frequency is induced by the Doppler effect. By applying our method to synthetic datasets, we demonstrate its ability to identify the unknown number of sources as well as the waveforms, the delays, and the strengths of the signals. Using Bayesian analysis, we also evaluate estimation uncertainties and identify the region of likelihood where the positions of the sources can be found. PMID:29518126

  7. Nonnegative Matrix Factorization for identification of unknown number of sources emitting delayed signals.

    PubMed

    Iliev, Filip L; Stanev, Valentin G; Vesselinov, Velimir V; Alexandrov, Boian S

    2018-01-01

    Factor analysis is broadly used as a powerful unsupervised machine learning tool for reconstruction of hidden features in recorded mixtures of signals. In the case of a linear approximation, the mixtures can be decomposed by a variety of model-free Blind Source Separation (BSS) algorithms. Most of the available BSS algorithms consider an instantaneous mixing of signals, while the case when the mixtures are linear combinations of signals with delays is less explored. Especially difficult is the case when the number of sources of the signals with delays is unknown and has to be determined from the data as well. To address this problem, in this paper, we present a new method based on Nonnegative Matrix Factorization (NMF) that is capable of identifying: (a) the unknown number of the sources, (b) the delays and speed of propagation of the signals, and (c) the locations of the sources. Our method can be used to decompose records of mixtures of signals with delays emitted by an unknown number of sources in a nondispersive medium, based only on recorded data. This is the case, for example, when electromagnetic signals from multiple antennas are received asynchronously; or mixtures of acoustic or seismic signals recorded by sensors located at different positions; or when a shift in frequency is induced by the Doppler effect. By applying our method to synthetic datasets, we demonstrate its ability to identify the unknown number of sources as well as the waveforms, the delays, and the strengths of the signals. Using Bayesian analysis, we also evaluate estimation uncertainties and identify the region of likelihood where the positions of the sources can be found.

  8. Properties of murine embryonic stem cells maintained on human foreskin fibroblasts without LIF.

    PubMed

    Meng, G L; Zur Nieden, N I; Liu, S Y; Cormier, J T; Kallos, M S; Rancourt, D E

    2008-04-01

    In embryonic stem (ES) cells, leukemia inhibitory factor (LIF)/STAT3, wnt and nodal/activin signaling are mainly active to control pluripotency during expansion. To maintain pluripotency, ES cells are typically cultured on feeder cells of varying origins. Murine ES cells are commonly cultured on murine embryonic fibroblasts (MEFs), which senesce early and must be frequently prepared. This process is laborious and leads to batch variation presenting a challenge for high-throughput ES cell expansion. Although some cell lines can be sustained by exogenous LIF, this method is costly. We present here a novel and inexpensive culture method for expanding murine ES cells on human foreskin fibroblast (HFF) feeders. After 20 passages on HFFs without LIF, ES cell lines showed normal expression levels of pluripotency markers, maintained a normal karyotype and retained the ability to contribute to the germline. As HFFs do not senesce for at least 62 passages, they present a vast supply of feeders. Copyright 2007 Wiley-Liss, Inc.

  9. RNF11 is a multifunctional modulator of growth factor receptor signalling and transcriptional regulation.

    PubMed

    Azmi, Peter; Seth, Arun

    2005-11-01

    Our laboratory has found that the 154aa RING finger protein 11 (RNF11), has modular domains and motifs including a RING-H2 finger domain, a PY motif, an ubiquitin interacting motif (UIM), a 14-3-3 binding sequence and an AKT phosphorylation site. RNF11 represents a unique protein with no other known immediate family members yet described. Comparative genetic analysis has shown that RNF11 is highly conserved throughout evolution. This may indicate a conserved and non-redundant role for the RNF11 protein. Molecular binding assays using RNF11 have shown that RNF11 has important roles in growth factor signalling, ubiquitination and transcriptional regulation. RNF11 has been shown to interact with HECT-type E3 ubiquitin ligases Nedd4, AIP4, Smurf1 and Smurf2, as well as with Cullin1, the core protein in the multi-subunit SCF E3 ubiquitin ligase complex. Work done in our laboratory has shown that RNF11 is capable of antagonizing Smurf2-mediated inhibition of TGFbeta signalling. Furthermore, RNF11 is capable of degrading AMSH, a positive regulator of both TGFbeta and EGFR signalling pathways. Recently, we have found that RNF11 can directly enhance TGFbeta signalling through a direct association with Smad4, the common signal transducer and transcription factor in the TGFbeta, BMP, and Activin pathways. Through its association with Smad4 and other transcription factors, RNF11 may have a role in direct transcriptional regulation. Our laboratory and others have found nearly 80 protein interactions for RNF11, placing RNF11 at the cross-roads of cell signalling and transcriptional regulation. RNF11 is highly expressed in breast tumours. Deregulation of RNF11 function may prove to be harmful to patient therapeutic outcomes. RNF11 may therefore provide a novel target for cancer therapeutics. The purpose of this review is to discuss the role of RNF11 in cell signalling and transcription factor modulation with special attention given to the ubiquitin-proteasomal pathway, TGFbeta

  10. Pluripotency factors in embryonic stem cells regulate differentiation into germ layers.

    PubMed

    Thomson, Matt; Liu, Siyuan John; Zou, Ling-Nan; Smith, Zack; Meissner, Alexander; Ramanathan, Sharad

    2011-06-10

    Cell fate decisions are fundamental for development, but we do not know how transcriptional networks reorganize during the transition from a pluripotent to a differentiated cell state. Here, we asked how mouse embryonic stem cells (ESCs) leave the pluripotent state and choose between germ layer fates. By analyzing the dynamics of the transcriptional circuit that maintains pluripotency, we found that Oct4 and Sox2, proteins that maintain ESC identity, also orchestrate germ layer fate selection. Oct4 suppresses neural ectodermal differentiation and promotes mesendodermal differentiation; Sox2 inhibits mesendodermal differentiation and promotes neural ectodermal differentiation. Differentiation signals continuously and asymmetrically modulate Oct4 and Sox2 protein levels, altering their binding pattern in the genome, and leading to cell fate choice. The same factors that maintain pluripotency thus also integrate external signals and control lineage selection. Our study provides a framework for understanding how complex transcription factor networks control cell fate decisions in progenitor cells. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Retrogradely Transported TrkA Endosomes Signal Locally within Dendrites to Maintain Sympathetic Neuron Synapses.

    PubMed

    Lehigh, Kathryn M; West, Katherine M; Ginty, David D

    2017-04-04

    Sympathetic neurons require NGF from their target fields for survival, axonal target innervation, dendritic growth and formation, and maintenance of synaptic inputs from preganglionic neurons. Target-derived NGF signals are propagated retrogradely, from distal axons to somata of sympathetic neurons via TrkA signaling endosomes. We report that a subset of TrkA endosomes that are transported from distal axons to cell bodies translocate into dendrites, where they are signaling competent and move bidirectionally, in close proximity to synaptic protein clusters. Using a strategy for spatially confined inhibition of TrkA kinase activity, we found that distal-axon-derived TrkA signaling endosomes are necessary within sympathetic neuron dendrites for maintenance of synapses. Thus, TrkA signaling endosomes have unique functions in different cellular compartments. Moreover, target-derived NGF mediates circuit formation and synapse maintenance through TrkA endosome signaling within dendrites to promote aggregation of postsynaptic protein complexes. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  12. Dexras1 links glucocorticoids to insulin-like growth factor-1 signaling in adipogenesis

    PubMed Central

    Kim, Hyo Jung; Cha, Jiyoung Y.; Seok, Jo Woon; Choi, Yoonjeong; Yoon, Bo Kyung; Choi, Hyeonjin; Yu, Jung Hwan; Song, Su Jin; Kim, Ara; Lee, Hyemin; Kim, Daeun; Han, Ji Yoon; Kim, Jae-woo

    2016-01-01

    Glucocorticoids are associated with obesity, but the underlying mechanism by which they function remains poorly understood. Previously, we showed that small G protein Dexras1 is expressed by glucocorticoids and leads to adipocyte differentiation. In this study, we explored the mechanism by which Dexras1 mediates adipogenesis and show a link to the insulin-like growth factor-1 (IGF-1) signaling pathway. Without Dexras1, the activation of MAPK and subsequent phosphorylation of CCAAT/enhancer binding protein β (C/EBPβ) is abolished, thereby inhibiting mitotic clonal expansion and further adipocyte differentiation. Dexras1 translocates to the plasma membrane upon insulin or IGF-1 treatment, for which the unique C-terminal domain (amino acids 223–276) is essential. Dexras1-dependent MAPK activation is selectively involved in the IGF-1 signaling, because another Ras protein, H-ras localized to the plasma membrane independently of insulin treatment. Moreover, neither epidermal growth factor nor other cell types shows Dexras1-dependent MAPK activation, indicating the importance of Dexras1 in IGF-1 signaling in adipogenesis. Dexras1 interacts with Shc and Raf, indicating that Dexras1-induced activation of MAPK is largely dependent on the Shc-Grb2-Raf complex. These results suggest that Dexras1 is a critical mediator of the IGF-1 signal to activate MAPK, linking glucocorticoid signaling to IGF-1 signaling in adipogenesis. PMID:27345868

  13. Hedgehog signaling contributes to basic fibroblast growth factor-regulated fibroblast migration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhu, Zhong Xin; Sun, Cong Cong; Wenzhou People's Hospital, Wenzhou, Zhejiang

    Fibroblast migration is a central process in skin wound healing, which requires the coordination of several types of growth factors. bFGF, a well-known fibroblast growth factor (FGF), is able to accelerate fibroblast migration; however, the underlying mechanism of bFGF regulation fibroblast migration remains unclear. Through the RNA-seq analysis, we had identified that the hedgehog (Hh) canonical pathway genes including Smoothened (Smo) and Gli1, were regulated by bFGF. Further analysis revealed that activation of the Hh pathway via up-regulation of Smo promoted fibroblast migration, invasion, and skin wound healing, but which significantly reduced by GANT61, a selective antagonist of Gli1/Gli2. Westernmore » blot analyses and siRNA transfection assays demonstrated that Smo acted upstream of phosphoinositide 3-kinase (PI3K)-c-Jun N-terminal kinase (JNK)-β-catenin to promote cell migration. Moreover, RNA-seq and qRT-PCR analyses revealed that Hh pathway genes including Smo and Gli1 were under control of β-catenin, suggesting that β-catenin turn feedback activates Hh signaling. Taken together, our analyses identified a new bFGF-regulating mechanism by which Hh signaling regulates human fibroblast migration, and the data presented here opens a new avenue for the wound healing therapy. - Highlights: • bFGF regulates Hedgehog (Hh) signaling in fibroblasts. • The Smo and Gli two master regulators of Hh signaling positively regulate fibroblast migration. • Smo facilitates β-catenin nuclear translocation via activation PI3K/JNK/GSK3β. • β-catenin positively regulates fibroblast cell migration and the expression of Hh signaling genes including Smo and Gli.« less

  14. Social costs enforce honesty of a dynamic signal of motivation.

    PubMed

    Ligon, Russell A; McGraw, Kevin J

    2016-10-26

    Understanding the processes that promote signal reliability may provide important insights into the evolution of diverse signalling strategies among species. The signals that animals use to communicate must comprise mechanisms that prohibit or punish dishonesty, and social costs of dishonesty have been demonstrated for several fixed morphological signals (e.g. colour badges of birds and wasps). The costs maintaining the honesty of dynamic signals, which are more flexible and potentially cheatable, are unknown. Using an experimental manipulation of the dynamic visual signals used by male veiled chameleons (Chamaeleo calyptratus) during aggressive interactions, we tested the idea that the honesty of rapid colour change signals is maintained by social costs. Our results reveal that social costs are an important mechanism maintaining the honesty of these dynamic colour signals-'dishonest' chameleons whose experimentally manipulated coloration was incongruent with their contest behaviour received more physical aggression than 'honest' individuals. This is the first demonstration, to the best our knowledge, that the honesty of a dynamic signal of motivation-physiological colour change-can be maintained by the social costliness of dishonesty. Behavioural responses of signal receivers, irrespective of any specific detection mechanisms, therefore prevent chameleon cheaters from prospering. © 2016 The Author(s).

  15. Corticotropin-Releasing Factor Mediates Pain-Induced Anxiety through the ERK1/2 Signaling Cascade in Locus Coeruleus Neurons

    PubMed Central

    Borges, Gisela Patrícia; Micó, Juan Antonio; Neto, Fani Lourença

    2015-01-01

    Background: The corticotropin-releasing factor is a stress-related neuropeptide that modulates locus coeruleus activity. As locus coeruleus has been involved in pain and stress-related patologies, we tested whether the pain-induced anxiety is a result of the corticotropin-releasing factor released in the locus coeruleus. Methods: Complete Freund’s adjuvant-induced monoarthritis was used as inflammatory chronic pain model. α-Helical corticotropin-releasing factor receptor antagonist was microinjected into the contralateral locus coeruleus of 4-week-old monoarthritic animals. The nociceptive and anxiety-like behaviors, as well as phosphorylated extracellular signal-regulated kinases 1/2 and corticotropin-releasing factor receptors expression, were quantified in the paraventricular nucleus and locus coeruleus. Results: Monoarthritic rats manifested anxiety and increased phosphorylated extracellular signal-regulated kinases 1/2 levels in the locus coeruleus and paraventricular nucleus, although the expression of corticotropin-releasing factor receptors was unaltered. α-Helical corticotropin-releasing factor antagonist administration reversed both the anxiogenic-like behavior and the phosphorylated extracellular signal-regulated kinases 1/2 levels in the locus coeruleus. Conclusions: Pain-induced anxiety is mediated by corticotropin-releasing factor neurotransmission in the locus coeruleus through extracellular signal-regulated kinases 1/2 signaling cascade. PMID:25716783

  16. Cell signaling and transcription factor genes expressed during whole body regeneration in a colonial chordate.

    PubMed

    Rinkevich, Yuval; Rinkevich, Baruch; Reshef, Ram

    2008-10-12

    The restoration of adults from fragments of blood vessels in botryllid ascidians (termed whole body regeneration [WBR]) represents an inimitable event in the chordates, which is poorly understood on the mechanistic level. To elucidate mechanisms underlying this phenomenon, a subtracted EST library for early WBR stages was previously assembled, revealing 76 putative genes belonging to major signaling pathways, including Notch/Delta, JAK/STAT, protein kinases, nuclear receptors, Ras oncogene family members, G-Protein coupled receptor (GPCR) and transforming growth factor beta (TGF-beta) signaling. RT-PCR on selected transcripts documented specific up-regulation in only regenerating fragments, pointing to a broad activation of these signaling pathways at onset of WBR. The followed-up expression pattern of seven representative transcripts from JAK/STAT signaling (Bl-STAT), the Ras oncogene family (Bl-Rap1A, Bl-Rab-33), the protein kinase family (Bl-Mnk), Bl-Cnot, Bl-Slit and Bl-Bax inhibitor, revealed systemic and site specific activations during WBR in a sub-population of circulatory cells. WBR in the non-vertebrate chordate Botrylloides leachi is a multifaceted phenomenon, presided by a complex array of cell signaling and transcription factors. Above results, provide a first insight into the whole genome molecular machinery of this unique regeneration process, and reveal the broad participation of cell signaling and transcription factors in the process. While regeneration involves the participation of specific cell populations, WBR signals are systemically expressed at the organism level.

  17. Involvement of Epidermal Growth Factor Receptor Signaling in Estrogen Inhibition of Oocyte Maturation Mediated Through the G Protein-Coupled Estrogen Receptor (Gper) in Zebrafish (Danio rerio)1

    PubMed Central

    Peyton, Candace; Thomas, Peter

    2011-01-01

    Oocyte maturation (OM) in teleosts is under precise hormonal control by progestins and estrogens. We show here that estrogens activate an epidermal growth factor receptor (Egfr) signaling pathway in fully grown, denuded zebrafish (Danio rerio) oocytes through the G protein-coupled estrogen receptor (Gper; also known as GPR30) to maintain oocyte meiotic arrest in a germinal vesicle breakdown (GVBD) bioassay. A GPER-specific antagonist, G-15, increased spontaneous OM, indicating that the inhibitory estrogen actions on OM are mediated through Gper. Estradiol-17beta-bovine serum albumin, which cannot enter oocytes, decreased GVBD, whereas treatment with actinomycin D did not block estrogen's inhibitory effects, suggesting that estrogens act at the cell surface via a nongenomic mechanism to prevent OM. The intracellular tyrosine kinase (Src) inhibitor, PP2, blocked estrogen inhibition of OM. Expression of egfr mRNA and Egfr protein were detected in denuded zebrafish oocytes. The matrix metalloproteinase (MMP) inhibitor, ilomastat, which prevents the release of heparin-bound epidermal growth factor, increased spontaneous OM, whereas the MMP activator, interleukin-1alpha, decreased spontaneous OM. Moreover, inhibitors of EGFR (ErbB1) and extracellular-related kinase 1 and 2 (Erk1/2; official symbol Mapk3/1) increased spontaneous OM. In addition, estradiol-17beta and the GPER agonist, G-1, increased phosphorylation of Erk, and this was abrogated by simultaneous treatment with the EGFR inhibitor. Taken together, these results suggest that estrogens act through Gper to maintain meiotic arrest via an Src kinase-dependent G-protein betagamma subunit signaling pathway involving transactivation of egfr and phosphorylation of Mapk3/1. To our knowledge, this is the first evidence that EGFR signaling in vertebrate oocytes can prevent meiotic progression. PMID:21349822

  18. Who succeeds in maintaining weight loss? A conceptual review of factors associated with weight loss maintenance and weight regain.

    PubMed

    Elfhag, K; Rössner, S

    2005-02-01

    Weight loss is difficult to achieve and maintaining the weight loss is an even greater challenge. The identification of factors associated with weight loss maintenance can enhance our understanding for the behaviours and prerequisites that are crucial in sustaining a lowered body weight. In this paper we have reviewed the literature on factors associated with weight loss maintenance and weight regain. We have used a definition of weight maintenance implying intentional weight loss that has subsequently been maintained for at least 6 months. According to our review, successful weight maintenance is associated with more initial weight loss, reaching a self-determined goal weight, having a physically active lifestyle, a regular meal rhythm including breakfast and healthier eating, control of over-eating and self-monitoring of behaviours. Weight maintenance is further associated with an internal motivation to lose weight, social support, better coping strategies and ability to handle life stress, self-efficacy, autonomy, assuming responsibility in life, and overall more psychological strength and stability. Factors that may pose a risk for weight regain include a history of weight cycling, disinhibited eating, binge eating, more hunger, eating in response to negative emotions and stress, and more passive reactions to problems.

  19. Social costs enforce honesty of a dynamic signal of motivation

    PubMed Central

    McGraw, Kevin J.

    2016-01-01

    Understanding the processes that promote signal reliability may provide important insights into the evolution of diverse signalling strategies among species. The signals that animals use to communicate must comprise mechanisms that prohibit or punish dishonesty, and social costs of dishonesty have been demonstrated for several fixed morphological signals (e.g. colour badges of birds and wasps). The costs maintaining the honesty of dynamic signals, which are more flexible and potentially cheatable, are unknown. Using an experimental manipulation of the dynamic visual signals used by male veiled chameleons (Chamaeleo calyptratus) during aggressive interactions, we tested the idea that the honesty of rapid colour change signals is maintained by social costs. Our results reveal that social costs are an important mechanism maintaining the honesty of these dynamic colour signals—‘dishonest’ chameleons whose experimentally manipulated coloration was incongruent with their contest behaviour received more physical aggression than ‘honest’ individuals. This is the first demonstration, to the best our knowledge, that the honesty of a dynamic signal of motivation—physiological colour change—can be maintained by the social costliness of dishonesty. Behavioural responses of signal receivers, irrespective of any specific detection mechanisms, therefore prevent chameleon cheaters from prospering. PMID:27798310

  20. Involvement of nuclear factor {kappa}B in platelet CD40 signaling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hachem, Ahmed; Yacoub, Daniel; Centre Hospitalier Universite de Montreal, 264 boul. Rene-Levesque est, Montreal, Quebec, Canada H2X 1P1

    Highlights: Black-Right-Pointing-Pointer sCD40L induces TRAF2 association to CD40 and NF-{kappa}B activation in platelets. Black-Right-Pointing-Pointer I{kappa}B{alpha} phosphorylation downstream of CD40L/CD40 signaling is independent of p38 MAPK phosphorylation. Black-Right-Pointing-Pointer I{kappa}B{alpha} is required for sCD40L-induced platelet activation and potentiation of aggregation. -- Abstract: CD40 ligand (CD40L) is a thrombo-inflammatory molecule that predicts cardiovascular events. Platelets constitute the major source of soluble CD40L (sCD40L), which has been shown to potentiate platelet activation and aggregation, in a CD40-dependent manner, via p38 mitogen activated protein kinase (MAPK) and Rac1 signaling. In many cells, the CD40L/CD40 dyad also induces activation of nuclear factor kappa B (NF-{kappa}B). Givenmore » that platelets contain NF-{kappa}B, we hypothesized that it may be involved in platelet CD40 signaling and function. In human platelets, sCD40L induces association of CD40 with its adaptor protein the tumor necrosis factor receptor associated factor 2 and triggers phosphorylation of I{kappa}B{alpha}, which are abolished by CD40L blockade. Inhibition of I{kappa}B{alpha} phosphorylation reverses sCD40L-induced I{kappa}B{alpha} phosphorylation without affecting p38 MAPK phosphorylation. On the other hand, inhibition of p38 MAPK phosphorylation has no effect on I{kappa}B{alpha} phosphorylation, indicating a divergence in the signaling pathway originating from CD40 upon its ligation. In functional studies, inhibition of I{kappa}B{alpha} phosphorylation reverses sCD40L-induced platelet activation and potentiation of platelet aggregation in response to a sub-threshold concentration of collagen. This study demonstrates that the sCD40L/CD40 axis triggers NF-{kappa}B activation in platelets. This signaling pathway plays a critical role in platelet activation and aggregation upon sCD40L stimulation and may represent an important target against

  1. Signaling by Kit protein-tyrosine kinase--the stem cell factor receptor.

    PubMed

    Roskoski, Robert

    2005-11-11

    Signaling by stem cell factor and Kit, its receptor, plays important roles in gametogenesis, hematopoiesis, mast cell development and function, and melanogenesis. Moreover, human and mouse embryonic stem cells express Kit transcripts. Stem cell factor exists as both a soluble and a membrane-bound glycoprotein while Kit is a receptor protein-tyrosine kinase. The complete absence of stem cell factor or Kit is lethal. Deficiencies of either produce defects in red and white blood cell production, hypopigmentation, and sterility. Gain-of-function mutations of Kit are associated with several human neoplasms including acute myelogenous leukemia, gastrointestinal stromal tumors, and mastocytomas. Kit consists of an extracellular domain, a transmembrane segment, a juxtamembrane segment, and a protein kinase domain that contains an insert of about 80 amino acid residues. Binding of stem cell factor to Kit results in receptor dimerization and activation of protein kinase activity. The activated receptor becomes autophosphorylated at tyrosine residues that serve as docking sites for signal transduction molecules containing SH2 domains. The adaptor protein APS, Src family kinases, and Shp2 tyrosyl phosphatase bind to phosphotyrosine 568. Shp1 tyrosyl phosphatase and the adaptor protein Shc bind to phosphotyrosine 570. C-terminal Src kinase homologous kinase and the adaptor Shc bind to both phosphotyrosines 568 and 570. These residues occur in the juxtamembrane segment of Kit. Three residues in the kinase insert domain are phosphorylated and attract the adaptor protein Grb2 (Tyr703), phosphatidylinositol 3-kinase (Tyr721), and phospholipase Cgamma (Tyr730). Phosphotyrosine 900 in the distal kinase domain binds phosphatidylinositol 3-kinase which in turn binds the adaptor protein Crk. Phosphotyrosine 936, also in the distal kinase domain, binds the adaptor proteins APS, Grb2, and Grb7. Kit has the potential to participate in multiple signal transduction pathways as a result of

  2. Cortical DNA methylation maintains remote memory.

    PubMed

    Miller, Courtney A; Gavin, Cristin F; White, Jason A; Parrish, R Ryley; Honasoge, Avinash; Yancey, Christopher R; Rivera, Ivonne M; Rubio, María D; Rumbaugh, Gavin; Sweatt, J David

    2010-06-01

    A behavioral memory's lifetime represents multiple molecular lifetimes, suggesting the necessity for a self-perpetuating signal. One candidate is DNA methylation, a transcriptional repression mechanism that maintains cellular memory throughout development. We found that persistent, gene-specific cortical hypermethylation was induced in rats by a single, hippocampus-dependent associative learning experience and pharmacologic inhibition of methylation 1 month after learning disrupted remote memory. We propose that the adult brain utilizes DNA methylation to preserve long-lasting memories.

  3. Tumor necrosis factor-α enhances microvascular tone and reduces blood flow in the cochlea via enhanced sphingosine-1-phosphate signaling.

    PubMed

    Scherer, Elias Q; Yang, Jingli; Canis, Martin; Reimann, Katrin; Ivanov, Karolina; Diehl, Christian D; Backx, Peter H; Wier, W Gil; Strieth, Sebastian; Wangemann, Philine; Voigtlaender-Bolz, Julia; Lidington, Darcy; Bolz, Steffen-Sebastian

    2010-11-01

    We sought to demonstrate that tumor necrosis factor (TNF)-α, via sphingosine-1-phosphate signaling, has the potential to alter cochlear blood flow and thus, cause ischemic hearing loss. We performed intravital fluorescence microscopy to measure blood flow and capillary diameter in anesthetized guinea pigs. To measure capillary diameter ex vivo, capillary beds from the gerbil spiral ligament were isolated from the cochlear lateral wall and maintained in an organ bath. Isolated gerbil spiral modiolar arteries, maintained and transfected in organ culture, were used to measure calcium sensitivity (calcium-tone relationship). In a clinical study, a total of 12 adult patients presenting with typical symptoms of sudden hearing loss who were not responsive or only partially responsive to prednisolone treatment were identified and selected for etanercept treatment. Etanercept (25 mg s.c.) was self-administered twice a week for 12 weeks. TNF-α induced a proconstrictive state throughout the cochlear microvasculature, which reduced capillary diameter and cochlear blood flow in vivo. In vitro isolated preparations of the spiral modiolar artery and spiral ligament capillaries confirmed these observations. Antagonizing sphingosine-1-phosphate receptor 2 subtype signaling (by 1 μmol/L JTE013) attenuated the effects of TNF-α in all models. TNF-α activated sphingosine kinase 1 (Sk1) and induced its translocation to the smooth muscle cell membrane. Expression of a dominant-negative Sk1 mutant (Sk1(G82D)) eliminated both baseline spiral modiolar artery calcium sensitivity and TNF-α effects, whereas a nonphosphorylatable Sk1 mutant (Sk1(S225A)) blocked the effects of TNF-α only. A small group of etanercept-treated, hearing loss patients recovered according to a 1-phase exponential decay (half-life=1.56 ± 0.20 weeks), which matched the kinetics predicted for a vascular origin. TNF-α indeed reduces cochlear blood flow via activation of vascular sphingosine-1-phosphate signaling

  4. Genetic screening of Wnt signaling factors in advanced retinopathy of prematurity

    PubMed Central

    Takahashi, Hiroshi; Orimo, Hideo; Hiraoka, Miina; Ogata, Tsutomu; Azuma, Noriyuki

    2010-01-01

    Purpose To evaluate the possibility of genetic involvement in retinopathy of prematurity (ROP). Although ROP is most often associated with low birthweight and low gestational age, these factors do not necessarily predict the severity of ROP. The possible involvement of other factors, including genetic variants, has been considered. Familial exudative vitreoretinopathy (FEVR) is a hereditary vitreoretinal disorder with clinical manifestations similar to those of ROP. Three genes involving the wingless/int1 (Wnt) receptor signaling pathway—FZD4 for frizzled 4, LRP5 for low-density lipoprotein receptor-related protein 5, and ND for Norrie disease protein—are associated with the development of FEVR. Methods In the present study, 17 Japanese patients with advanced ROP were screened for these three candidate genes of FEVR. Genomic DNA from each patient was subjected to PCR and direct sequencing of the ND, FZD4, and LRP5 genes. Results One patient had a heterozygous mutation in the 5′ untranslated region of the ND gene. Another had a leucine insertion in the signal peptide of LRP5. None showed any mutation in FZD4. Conclusions These findings suggest that genetic changes in the Wnt receptor signaling pathway associate to the development of advanced ROP. PMID:21151595

  5. Targeting fibroblast growth factor receptor signaling inhibits prostate cancer progression.

    PubMed

    Feng, Shu; Shao, Longjiang; Yu, Wendong; Gavine, Paul; Ittmann, Michael

    2012-07-15

    Extensive correlative studies in human prostate cancer as well as studies in vitro and in mouse models indicate that fibroblast growth factor receptor (FGFR) signaling plays an important role in prostate cancer progression. In this study, we used a probe compound for an FGFR inhibitor, which potently inhibits FGFR-1-3 and significantly inhibits FGFR-4. The purpose of this study is to determine whether targeting FGFR signaling from all four FGFRs will have in vitro activities consistent with inhibition of tumor progression and will inhibit tumor progression in vivo. Effects of AZ8010 on FGFR signaling and invasion were analyzed using immortalized normal prostate epithelial (PNT1a) cells and PNT1a overexpressing FGFR-1 or FGFR-4. The effect of AZ8010 on invasion and proliferation in vitro was also evaluated in prostate cancer cell lines. Finally, the impact of AZ8010 on tumor progression in vivo was evaluated using a VCaP xenograft model. AZ8010 completely inhibits FGFR-1 and significantly inhibits FGFR-4 signaling at 100 nmol/L, which is an achievable in vivo concentration. This results in marked inhibition of extracellular signal-regulated kinase (ERK) phosphorylation and invasion in PNT1a cells expressing FGFR-1 and FGFR-4 and all prostate cancer cell lines tested. Treatment in vivo completely inhibited VCaP tumor growth and significantly inhibited angiogenesis and proliferation and increased cell death in treated tumors. This was associated with marked inhibition of ERK phosphorylation in treated tumors. Targeting FGFR signaling is a promising new approach to treating aggressive prostate cancer.

  6. Decoupling the Functional Pleiotropy of Stem Cell Factor by Tuning c-Kit Signaling

    PubMed Central

    Ho, Chia Chi M.; Chhabra, Akanksha; Starkl, Philipp; Schnorr, Peter-John; Wilmes, Stephan; Moraga, Ignacio; Kwon, Hye-Sook; Gaudenzio, Nicolas; Sibilano, Riccardo; Wehrman, Tom S.; Gakovic, Milica; Sockolosky, Jonathan T.; Tiffany, Matthew R.; Ring, Aaron M.; Piehler, Jacob; Weissman, Irving L.; Galli, Stephen J.; Shizuru, Judith A.; Garcia, K. Christopher

    2017-01-01

    SUMMARY Most secreted growth factors and cytokines are functionally pleiotropic because their receptors are expressed on diverse cell types. While important for normal mammalian physiology, pleiotropy limits the efficacy of cytokines and growth factors as therapeutics. Stem cell factor (SCF) is a growth factor that acts through the c-Kit receptor tyrosine kinase to elicit hematopoietic progenitor expansion, but can be toxic when administered in vivo because it concurrently activates mast cells. We engineered a mechanism-based SCF partial agonist that impaired c-Kit dimerization, truncating downstream signaling amplitude. This SCF variant elicited biased activation of hematopoietic progenitors over mast cells in vitro and in vivo. Mouse models of SCF-mediated anaphylaxis, radioprotection, and hematopoietic expansion revealed that this SCF partial agonist retained therapeutic efficacy while exhibiting virtually no anaphylactic off-target effects. The approach of biasing cell activation by tuning signaling thresholds and outputs has applications to many dimeric receptor-ligand systems. PMID:28283060

  7. Growth Factor Signaling and Memory Formation: Temporal and Spatial Integration of a Molecular Network

    ERIC Educational Resources Information Center

    Kopec, Ashley M.; Carew, Thomas J.

    2013-01-01

    Growth factor (GF) signaling is critically important for developmental plasticity. It also plays a crucial role in adult plasticity, such as that required for memory formation. Although different GFs interact with receptors containing distinct types of kinase domains, they typically signal through converging intracellular cascades (e.g.,…

  8. WNT signaling in stem cell biology and regenerative medicine.

    PubMed

    Katoh, Masaru

    2008-07-01

    WNT family members are secreted-type glycoproteins to orchestrate embryogenesis, to maintain homeostasis, and to induce pathological conditions. FZD1, FZD2, FZD3, FZD4, FZD5, FZD6, FZD7, FZD8, FZD9, FZD10, LRP5, LRP6, and ROR2 are transmembrane receptors transducing WNT signals based on ligand-dependent preferentiality for caveolin- or clathrin-mediated endocytosis. WNT signals are transduced to canonical pathway for cell fate determination, and to non-canonical pathways for regulation of planar cell polarity, cell adhesion, and motility. MYC, CCND1, AXIN2, FGF20, WISP1, JAG1, DKK1 and Glucagon are target genes of canonical WNT signaling cascade, while CD44, Vimentin and STX5 are target genes of non-canonical WNT signaling cascades. However, target genes of WNT signaling cascades are determined in a context-dependent manner due to expression profile of transcription factors and epigenetic status. WNT signaling cascades network with Notch, FGF, BMP and Hedgehog signaling cascades to regulate the balance of stem cells and progenitor cells. Here WNT signaling in embryonic stem cells, neural stem cells, mesenchymal stem cells, hematopoietic stem cells, and intestinal stem cells will be reviewed. WNT3, WNT5A and WNT10B are expressed in undifferentiated human embryonic stem cells, while WNT6, WNT8B and WNT10B in endoderm precursor cells. Wnt6 is expressed in intestinal crypt region for stem or progenitor cells. TNF/alpha-WNT10B signaling is a negative feedback loop to maintain homeostasis of adipose tissue and gastrointestinal mucosa with chronic inflammation. Recombinant WNT protein or WNT mimetic (circular peptide, small molecule compound, or RNA aptamer) in combination with Notch mimetic, FGF protein, and BMP protein opens a new window to tissue engineering for regenerative medicine.

  9. Tunable Q-Factor RF Cavity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Balcazar, Mario D.; Yonehara, Katsuya; Moretti, Alfred

    Intense neutrino beam is a unique probe for researching beyond the standard model. Fermilab is the main institution to produce the most powerful and widespectrum neutrino beam. From that respective, a radiation robust beam diagnostic system is a critical element in order to maintain the quality of the neutrino beam. Within this context, a novel radiation-resistive beam profile monitor based on a gasfilled RF cavity is proposed. The goal of this measurement is to study a tunable Qfactor RF cavity to determine the accuracy of the RF signal as a function of the quality factor. Specifically, measurement error of themore » Q-factor in the RF calibration is investigated. Then, the RF system will be improved to minimize signal error.« less

  10. Dual role of Brg chromatin remodeling factor in Sonic hedgehog signaling during neural development.

    PubMed

    Zhan, Xiaoming; Shi, Xuanming; Zhang, Zilai; Chen, Yu; Wu, Jiang I

    2011-08-02

    Sonic hedgehog (Shh) signaling plays diverse roles during animal development and adult tissue homeostasis through differential regulation of Gli family transcription factors. Dysregulated Shh signaling activities have been linked to birth defects and tumorigenesis. Here we report that Brg, an ATP-dependent chromatin remodeling factor, has dual functions in regulating Shh target gene expression. Using a Brg conditional deletion in Shh-responding neural progenitors and fibroblasts, we demonstrate that Brg is required both for repression of the basal expression and for the activation of signal-induced transcription of Shh target genes. In developing telencephalons deficient for Brg, Shh target genes were derepressed, whereas Brg-deleted cerebellar granule neuron precursors failed to respond to Shh to increase their proliferation. The repressor function of Brg was mediated through Gli3 and both the repressor and activator functions of Brg appeared to be independent of its ATPase activity. Furthermore, Brg facilitates Gli coactivator histone deacetylase (HDAC) binding to the regulatory regions of Shh target genes, providing a possible mechanism for its positive role in Shh signaling. Our results thus reveal that a complex chromatin regulation mechanism underlies the precise transcription outcomes of Shh signaling and its diverse roles during development.

  11. Membrane-To-Nucleus Signaling Links Insulin-Like Growth Factor-1- and Stem Cell Factor-Activated Pathways

    PubMed Central

    Hayashi, Yujiro; Asuzu, David T.; Gibbons, Simon J.; Aarsvold, Kirsten H.; Bardsley, Michael R.; Lomberk, Gwen A.; Mathison, Angela J.; Kendrick, Michael L.; Shen, K. Robert; Taguchi, Takahiro; Gupta, Anu; Rubin, Brian P.; Fletcher, Jonathan A.; Farrugia, Gianrico; Urrutia, Raul A.; Ordog, Tamas

    2013-01-01

    Stem cell factor (mouse: Kitl, human: KITLG) and insulin-like growth factor-1 (IGF1), acting via KIT and IGF1 receptor (IGF1R), respectively, are critical for the development and integrity of several tissues. Autocrine/paracrine KITLG-KIT and IGF1-IGF1R signaling are also activated in several cancers including gastrointestinal stromal tumors (GIST), the most common sarcoma. In murine gastric muscles, IGF1 promotes Kitl-dependent development of interstitial cells of Cajal (ICC), the non-neoplastic counterpart of GIST, suggesting cooperation between these pathways. Here, we report a novel mechanism linking IGF1-IGF1R and KITLG-KIT signaling in both normal and neoplastic cells. In murine gastric muscles, the microenvironment for ICC and GIST, human hepatic stellate cells (LX-2), a model for cancer niches, and GIST cells, IGF1 stimulated Kitl/KITLG protein and mRNA expression and promoter activity by activating several signaling pathways including AKT-mediated glycogen synthase kinase-3β inhibition (GSK3i). GSK3i alone also stimulated Kitl/KITLG expression without activating mitogenic pathways. Both IGF1 and GSK3i induced chromatin-level changes favoring transcriptional activation at the Kitl promoter including increased histone H3/H4 acetylation and H3 lysine (K) 4 methylation, reduced H3K9 and H3K27 methylation and reduced occupancy by the H3K27 methyltransferase EZH2. By pharmacological or RNA interference-mediated inhibition of chromatin modifiers we demonstrated that these changes have the predicted impact on KITLG expression. KITLG knock-down and immunoneutralization inhibited the proliferation of GIST cells expressing wild-type KIT, signifying oncogenic autocrine/paracrine KITLG-KIT signaling. We conclude that membrane-to-nucleus signaling involving GSK3i establishes a previously unrecognized link between the IGF1-IGF1R and KITLG-KIT pathways, which is active in both physiologic and oncogenic contexts and can be exploited for therapeutic purposes. PMID:24116170

  12. Quercetin Attenuates Cell Survival, Inflammation, and Angiogenesis via Modulation of AKT Signaling in Murine T-Cell Lymphoma.

    PubMed

    Maurya, Akhilendra Kumar; Vinayak, Manjula

    2017-04-01

    AKT signaling is important to maintaining normal physiology. Hyperactivation of AKT signaling is frequent in cancer, which maintains a high oxidative state in a tumor microenvironment that is needed for tumor adaptation. Therefore, antioxidants are proposed to exhibit anticancer properties by interfering with the tumor microenvironment. Quercetin is an ubiquitous bioactive antioxidant rich in vegetables and beverages. The present study aimed to analyze cancer preventive property of quercetin in ascite cells of Dalton's lymphoma-bearing mice. Protein level was determined by Western blotting. Nitric oxide (NO) level was estimated spectrophotometrically using Griess reagent. Results show downregulation in phosphorylation of AKT and PDK1 by quercetin, which was consistent with decreased phosphorylation of downstream survival factors such as BAD, GSK-3β, mTOR, and IkBα. Further, quercetin attenuated the levels of angiogenic factor VEGF-A and inflammatory enzymes COX-2 and iNOS as well as NO levels, whereas it increased the levels of phosphatase PTEN. Overall results suggest that quercetin modulates AKT signaling leading to attenuation of cell survival, inflammation, and angiogenesis in lymphoma-bearing mice.

  13. Increased expression of c-Ski as a co-repressor in transforming growth factor-beta signaling correlates with progression of esophageal squamous cell carcinoma.

    PubMed

    Fukuchi, Minoru; Nakajima, Masanobu; Fukai, Yasuyuki; Miyazaki, Tatsuya; Masuda, Norihiro; Sohda, Makoto; Manda, Ryokuhei; Tsukada, Katsuhiko; Kato, Hiroyuki; Kuwano, Hiroyuki

    2004-03-01

    Transforming growth factor-beta (TGF-beta) regulates cell growth inhibition, and inactivation of the TGF-beta signaling pathway contributes to tumor development. In our previous study, altered expression of TGF-beta, TGF-beta-specific receptors and Smad4 was shown to correlate with tumor progression in esophageal squamous cell carcinoma (SCC). These components, however, were maintained normally in some patients with esophageal SCC. In our study, the mechanism by which aggressive esophageal SCC maintains these components was investigated, with particular emphasis on the participation of c-Ski and SnoN as transcriptional co-repressors in TGF-beta signaling. Immunohistochemistry for c-Ski and SnoN was carried out on surgical specimens obtained from 80 patients with esophageal SCC. The expression of c-Ski and SnoN was also studied in 6 established cell lines derived from esophageal SCC and compared to an immortalized human esophageal cell line by Western blotting. High levels of expression of c-Ski, detected immunohistologically, were found to correlate with depth of invasion (p = 0.0080) and pathologic stage (p = 0.0447). There was, however, no significant correlation between expression of SnoN and clinicopathologic characteristics. A significant correlation between c-Ski and TGF-beta expression was observed. Moreover, in patients with TGF-beta negative expression, the survival rates of patients with c-Ski positive expression were significantly lower than those of patients with c-Ski negative expression (p = 0.0486). c-Ski was expressed at a high level in 5 of 6 cell lines derived from esophageal SCC compared to immortalized esophageal keratinocytes. Furthermore, the cyclin-dependent kinase (CDK) inhibitor, p21 that was up-regulated by TGF-beta signaling was expressed at a low level in the 5 cell lines. The expression of c-Ski protein as a transcriptional co-repressor in TGF-beta signaling seems to be correlated with tumor progression of esophageal SCC. Copyright 2003

  14. Cyclic mechanical strain maintains Nanog expression through PI3K/Akt signaling in mouse embryonic stem cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Horiuchi, Rie; Akimoto, Takayuki, E-mail: akimoto@m.u-tokyo.ac.jp; Institute for Biomedical Engineering, Consolidated Research Institute for Advanced Science and Medical Care, Waseda University, 513 Waseda-tsurumaki, Shinjuku, Tokyo 162-0041

    2012-08-15

    Mechanical strain has been reported to affect the proliferation/differentiation of many cell types; however, the effects of mechanotransduction on self-renewal as well as pluripotency of embryonic stem (ES) cells remains unknown. To investigate the effects of mechanical strain on mouse ES cell fate, we examined the expression of Nanog, which is an essential regulator of self-renewal and pluripotency as well as Nanog-associated intracellular signaling during uniaxial cyclic mechanical strain. The mouse ES cell line, CCE was plated onto elastic membranes, and we applied 10% strain at 0.17 Hz. The expression of Nanog was reduced during ES cell differentiation in responsemore » to the withdrawal of leukemia inhibitory factor (LIF); however, two days of cyclic mechanical strain attenuated this reduction of Nanog expression. On the other hand, the cyclic mechanical strain promoted PI3K-Akt signaling, which is reported as an upstream of Nanog transcription. The cyclic mechanical strain-induced Akt phosphorylation was blunted by the PI3K inhibitor wortmannin. Furthermore, cytochalasin D, an inhibitor of actin polymerization, also inhibited the mechanical strain-induced increase in phospho-Akt. These findings imply that mechanical force plays a role in regulating Nanog expression in ES cells through the actin cytoskeleton-PI3K-Akt signaling. -- Highlights: Black-Right-Pointing-Pointer The expression of Nanog, which is an essential regulator of 'stemness' was reduced during embryonic stem (ES) cell differentiation. Black-Right-Pointing-Pointer Cyclic mechanical strain attenuated the reduction of Nanog expression. Black-Right-Pointing-Pointer Cyclic mechanical strain promoted PI3K-Akt signaling and mechanical strain-induced Akt phosphorylation was blunted by the PI3K inhibitor and an inhibitor of actin polymerization.« less

  15. Equipment for the Transient Capture of Chaotic Microwave Signals

    DTIC Science & Technology

    2017-09-14

    estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the... times are needed and over-sampling by a factor of 8 is required so that the effective number of bits can be increased from the actual bit resolution... time acquisition of transient signals with analog bandwidths up to 70 GHz for one channel, and 30 GHz for two channels.. Training Opportunities

  16. EGF-dependent re-routing of vesicular recycling switches spontaneous phosphorylation suppression to EGFR signaling

    PubMed Central

    Baumdick, Martin; Brüggemann, Yannick; Schmick, Malte; Xouri, Georgia; Sabet, Ola; Davis, Lloyd; Chin, Jason W; Bastiaens, Philippe IH

    2015-01-01

    Autocatalytic activation of epidermal growth factor receptor (EGFR) coupled to dephosphorylating activity of protein tyrosine phosphatases (PTPs) ensures robust yet diverse responses to extracellular stimuli. The inevitable tradeoff of this plasticity is spontaneous receptor activation and spurious signaling. We show that a ligand-mediated switch in EGFR trafficking enables suppression of spontaneous activation while maintaining EGFR’s capacity to transduce extracellular signals. Autocatalytic phosphorylation of tyrosine 845 on unliganded EGFR monomers is suppressed by vesicular recycling through perinuclear areas with high PTP1B activity. Ligand-binding results in phosphorylation of the c-Cbl docking tyrosine and ubiquitination of the receptor. This secondary signal relies on EGF-induced EGFR self-association and switches suppressive recycling to directional trafficking. The re-routing regulates EGFR signaling response by the transit-time to late endosomes where it is switched-off by high PTP1B activity. This ubiquitin-mediated switch in EGFR trafficking is a uniquely suited solution to suppress spontaneous activation while maintaining responsiveness to EGF. DOI: http://dx.doi.org/10.7554/eLife.12223.001 PMID:26609808

  17. Smad7 enables STAT3 activation and promotes pluripotency independent of TGF-β signaling

    PubMed Central

    Yu, Yi; Gu, Shuchen; Li, Wenjian; Sun, Chuang; Chen, Fenfang; Xiao, Mu; Wang, Lei; Xu, Dewei; Li, Ye; Ding, Chen; Xia, Zongping; Li, Yi; Ye, Sheng; Xu, Pinglong; Zhao, Bin; Qin, Jun; Chen, Ye-Guang; Lin, Xia; Feng, Xin-Hua

    2017-01-01

    Smad7 is a negative feedback product of TGF-β superfamily signaling and fine tunes a plethora of pleiotropic responses induced by TGF-β ligands. However, its noncanonical functions independent of TGF-β signaling remain to be elucidated. Here, we show that Smad7 activates signal transducers and activators of transcription 3 (STAT3) signaling in maintaining mouse embryonic stem cell pluripotency in a manner independent of the TGF-β receptors, yet dependent on the leukemia inhibitory factor (LIF) coreceptor glycoprotein 130 (gp130). Smad7 directly binds to the intracellular domain of gp130 and disrupts the SHP2–gp130 or SOCS3–gp130 complex, thereby amplifying STAT3 activation. Consequently, Smad7 facilitates LIF-mediated self-renewal of mouse ESCs and is also critical for induced pluripotent stem cell reprogramming. This finding illustrates an uncovered role of the Smad7–STAT3 interplay in maintaining cell pluripotency and also implicates a mechanism involving Smad7 underlying cytokine-dependent regulation of cancer and inflammation. PMID:28874583

  18. The lysosomal membrane protein SCAV-3 maintains lysosome integrity and adult longevity

    PubMed Central

    Li, Yuan; Chen, Baohui; Zou, Wei; Wang, Xin; Wu, Yanwei; Zhao, Dongfeng; Sun, Yanan; Liu, Yubing

    2016-01-01

    Lysosomes degrade macromolecules and recycle metabolites as well as being involved in diverse processes that regulate cellular homeostasis. The lysosome is limited by a single phospholipid bilayer that forms a barrier to separate the potent luminal hydrolases from other cellular constituents, thus protecting the latter from unwanted degradation. The mechanisms that maintain lysosomal membrane integrity remain unknown. Here, we identified SCAV-3, the Caenorhabditis elegans homologue of human LIMP-2, as a key regulator of lysosome integrity, motility, and dynamics. Loss of scav-3 caused rupture of lysosome membranes and significantly shortened lifespan. Both of these phenotypes were suppressed by reinforced expression of LMP-1 or LMP-2, the C. elegans LAMPs, indicating that longevity requires maintenance of lysosome integrity. Remarkably, reduction in insulin/insulin-like growth factor 1 (IGF-1) signaling suppressed lysosomal damage and extended the lifespan in scav-3(lf) animals in a DAF-16–dependent manner. Our data reveal that SCAV-3 is essential for preserving lysosomal membrane stability and that modulation of lysosome integrity by the insulin/IGF-1 signaling pathway affects longevity. PMID:27810910

  19. Stromal Tissue Rigidity Promotes Mesenchymal Stem Cell-Mediated Corneal Wound Healing Through the Transforming Growth Factor β Signaling Pathway.

    PubMed

    Yang, Yun-Hsiang; Hsieh, Ting-Lieh; Ji, Andrea Tung-Qian; Hsu, Wei-Tse; Liu, Chia-Yu; Lee, Oscar Kuang-Sheng; Ho, Jennifer Hui-Chun

    2016-10-01

    The healing of a corneal epithelial defect is essential for preventing infectious corneal ulcers and subsequent blindness. We previously demonstrated that mesenchymal stem cells (MSCs) in the corneal stroma, through a paracrine mechanism, yield a more favorable therapeutic benefit for corneal wound re-epithelialization than do MSCs in the corneal epithelium. In this study, MSCs were grown on a matrix with the rigidity of the physiological human vitreous (1 kPa), corneal epithelium (8 kPa), or corneal stroma (25 kPa) for investigating the role of corneal tissue rigidity in MSC functions regarding re-epithelialization promotion. MSC growth on a 25-kPa dish significantly promoted the wound healing of human corneal epithelial (HCE-T) cells. Among growth factors contributing to corneal epithelial wound healing, corneal stromal rigidity selectively enhanced transforming growth factor-beta (TGF-β) secretion from MSCs. Inhibitors of TGF-β pan receptor, TGF-β receptor 1, and Smad2 dose dependently abrogated MSC-mediated HCE-T wound healing. Furthermore, MSCs growth on a matrix with corneal stromal rigidity enhanced the ability of themselves to promote corneal re-epithelialization by activating matrix metalloproteinase (MMP) expression and integrin β1 production in HCE-T cells through TGF-β signaling pathway activation. Smad2 activation resulted in the upregulation of MMP-2 and -13 expression in HCE-T cells, whereas integrin β1 production favored a Smad2-independent TGF-β pathway. Altogether, we conclude that corneal stromal rigidity is a critical factor for MSC-induced promotion of corneal re-epithelialization. The activation of the TGF-β signaling pathway, which maintains the balance between integrin and MMP expression, in HCE-T cells is the major pathway responsible for MSC-mediated wound healing. Stem Cells 2016;34:2525-2535. © 2016 AlphaMed Press.

  20. The role of SOCS3 in modulating leukaemia inhibitory factor signalling during murine placental development

    PubMed Central

    Boyle, Kristy; Robb, Lorraine

    2008-01-01

    Cytokines are an integral part of the adaptive and innate immune responses. The signalling pathways triggered by receptor engagement translate exposure to cytokine into a coordinated biological response. To contain these responses, the initiation, duration and magnitude of the signal is controlled at multiple levels. SOCS (suppressor of cytokine signalling) proteins act in a negative feedback loop to inhibit signal transduction. Mice with a deletion of SOCS3 die at midgestion due to placental insufficiency. SOCS3-null placentae have increased numbers of mature trophoblast giant cells, disruption of the labyrinthine layer and a decrease in the spongiotrophoblast layer. Genetic crosses have revealed that the phenotype is due to dysregulation of signalling downstream of the leukaemia inhibitory factor (LIF) receptor alpha (LIFRα) and that the ligand responsible for this, LIF, is produced by embryonic tissues and acts in a paracrine fashion. These observations highlight the role of LIF as an extrinsic factor regulating trophoblast differentiation in vivo. The creation of mice with conditional deletion of SOCS3 in different tissues has also uncovered critical roles for SOCS3 in the regulation of IL-6, G-CSF and leptin signalling. PMID:17408753

  1. The role of SOCS3 in modulating leukaemia inhibitory factor signalling during murine placental development.

    PubMed

    Boyle, Kristy; Robb, Lorraine

    2008-01-01

    Cytokines are an integral part of the adaptive and innate immune responses. The signalling pathways triggered by receptor engagement translate exposure to cytokine into a coordinated biological response. To contain these responses, the initiation, duration and magnitude of the signal is controlled at multiple levels. Suppressor of cytokine signalling (SOCS) proteins act in a negative feedback loop to inhibit signal transduction. Mice with a deletion of SOCS3 die at midgestion due to placental insufficiency. SOCS3-null placentae have increased numbers of mature trophoblast giant cells, disruption of the labyrinthine layer and a decrease in the spongiotrophoblast layer. Genetic crosses have revealed that the phenotype is due to dysregulation of signalling downstream of the leukaemia inhibitory factor (LIF) receptor alpha (LIFRalpha) and that the ligand responsible for this, LIF, is produced by embryonic tissues and acts in a paracrine fashion. These observations highlight the role of LIF as an extrinsic factor regulating trophoblast differentiation in vivo. The creation of mice with conditional deletion of SOCS3 in different tissues has also uncovered critical roles for SOCS3 in the regulation of IL-6, G-CSF and leptin signalling.

  2. WRKY transcription factors: key components in abscisic acid signalling.

    PubMed

    Rushton, Deena L; Tripathi, Prateek; Rabara, Roel C; Lin, Jun; Ringler, Patricia; Boken, Ashley K; Langum, Tanner J; Smidt, Lucas; Boomsma, Darius D; Emme, Nicholas J; Chen, Xianfeng; Finer, John J; Shen, Qingxi J; Rushton, Paul J

    2012-01-01

    WRKY transcription factors (TFs) are key regulators of many plant processes, including the responses to biotic and abiotic stresses, senescence, seed dormancy and seed germination. For over 15 years, limited evidence has been available suggesting that WRKY TFs may play roles in regulating plant responses to the phytohormone abscisic acid (ABA), notably some WRKY TFs are ABA-inducible repressors of seed germination. However, the roles of WRKY TFs in other aspects of ABA signalling, and the mechanisms involved, have remained unclear. Recent significant progress in ABA research has now placed specific WRKY TFs firmly in ABA-responsive signalling pathways, where they act at multiple levels. In Arabidopsis, WRKY TFs appear to act downstream of at least two ABA receptors: the cytoplasmic PYR/PYL/RCAR-protein phosphatase 2C-ABA complex and the chloroplast envelope-located ABAR-ABA complex. In vivo and in vitro promoter-binding studies show that the target genes for WRKY TFs that are involved in ABA signalling include well-known ABA-responsive genes such as ABF2, ABF4, ABI4, ABI5, MYB2, DREB1a, DREB2a and RAB18. Additional well-characterized stress-inducible genes such as RD29A and COR47 are also found in signalling pathways downstream of WRKY TFs. These new insights also reveal that some WRKY TFs are positive regulators of ABA-mediated stomatal closure and hence drought responses. Conversely, many WRKY TFs are negative regulators of seed germination, and controlling seed germination appears a common function of a subset of WRKY TFs in flowering plants. Taken together, these new data demonstrate that WRKY TFs are key nodes in ABA-responsive signalling networks. © 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

  3. 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.

  4. Additive Factors Analysis of Inhibitory Processing in the Stop-Signal Paradigm

    ERIC Educational Resources Information Center

    van den Wildenberg, W.P.M.; van der Molen, M.W.

    2004-01-01

    This article reports an additive factors analysis of choice reaction and selective stop processes manipulated in a stop-signal paradigm. Three experiments were performed in which stimulus discriminability (SD) and stimulus-response compatibility (SRC) were manipulated in a factorial fashion. In each experiment, the effects of SD and SRC were…

  5. Measurement of Epidermal Growth Factor Receptor-Derived Signals Within Plasma Membrane Clathrin Structures.

    PubMed

    Lucarelli, Stefanie; Delos Santos, Ralph Christian; Antonescu, Costin N

    2017-01-01

    The epidermal growth factor (EGF) receptor (EGFR) is an important regulator of cell growth, proliferation, survival, migration, and metabolism. EGF binding to EGFR triggers the activation of the receptor's intrinsic kinase activity, in turn eliciting the recruitment of many secondary signaling proteins and activation of downstream signals, such as the activation of phosphatidylinositol-3-kinase (PI3K) and Akt, a process requiring the phosphorylation of Gab1. While the identity of many signals that can be activated by EGFR has been revealed, how the spatiotemporal organization of EGFR signaling within cells controls receptor outcome remains poorly understood. Upon EGF binding at the plasma membrane, EGFR is internalized by clathrin-mediated endocytosis following recruitment to clathrin-coated pits (CCPs). Further, plasma membrane CCPs, but not EGFR internalization, are required for EGF-stimulated Akt phosphorylation. Signaling intermediates such as phosphorylated Gab1, which lead to Akt phosphorylation, are enriched within CCPs upon EGF stimulation. These findings indicate that some plasma membrane CCPs also serve as signaling microdomains required for certain facets of EGFR signaling and are enriched in key EGFR signaling intermediates. Understanding how the spatiotemporal organization of EGFR signals within CCP microdomains controls receptor signaling outcome requires imaging methods that can systematically resolve and analyze the properties of CCPs, EGFR and key signaling intermediates. Here, we describe methods using total internal reflection fluorescence microscopy imaging and analysis to systematically study the enrichment of EGFR and key EGFR-derived signals within CCPs.

  6. Ectopic Expression of JcWRKY Transcription Factor Confers Salinity Tolerance via Salicylic Acid Signaling.

    PubMed

    Agarwal, Parinita; Dabi, Mitali; Sapara, Komal K; Joshi, Priyanka S; Agarwal, Pradeep K

    2016-01-01

    Plants, being sessile, have developed intricate signaling network to specifically respond to the diverse environmental stress. The plant-specific WRKY TFs form one of the largest TF family and are involved in diverse plant processes, involving growth, development and stress signaling through auto and cross regulation with different genes and TFs. Here, we report the functional characterization of a salicylic acid -inducible JcWRKY TF. The JcWRKY overexpression confers salinity tolerance in transgenic tobacco, as was evident by increased chlorophyll content and seed germination potential. The transgenic plants showed increased soluble sugar, membrane stability, reduced electrolyte leakage and generation of reactive oxygen species (H 2 O 2 and [Formula: see text]) as compared to the wild type. Furthermore, the low SA treatment along with salinity improved the tolerance potential of the transgenics by maintaining ROS homeostasis and high K + /Na + ratio. The transcript expression of SA biosynthetic gene ICS1 and antioxidative enzymes ( CAT and SOD ) showed upregulation during stress. Thus, the present study reflects that JcWRKY is working in co-ordination with SA signaling to orchestrate the different biochemical and molecular pathways to maneuvre salt stress tolerance of the transgenic plants.

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

    PubMed Central

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

    2015-01-01

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

  8. Nociceptive tuning by stem cell factor/c-Kit signaling.

    PubMed

    Milenkovic, Nevena; Frahm, Christina; Gassmann, Max; Griffel, Carola; Erdmann, Bettina; Birchmeier, Carmen; Lewin, Gary R; Garratt, Alistair N

    2007-12-06

    The molecular mechanisms regulating the sensitivity of sensory circuits to environmental stimuli are poorly understood. We demonstrate here a central role for stem cell factor (SCF) and its receptor, c-Kit, in tuning the responsiveness of sensory neurons to natural stimuli. Mice lacking SCF/c-Kit signaling displayed profound thermal hypoalgesia, attributable to a marked elevation in the thermal threshold and reduction in spiking rate of heat-sensitive nociceptors. Acute activation of c-Kit by its ligand, SCF, resulted in a reduced thermal threshold and potentiation of heat-activated currents in isolated small-diameter neurons and thermal hyperalgesia in mice. SCF-induced thermal hyperalgesia required the TRP family cation channel TRPV1. Lack of c-Kit signaling during development resulted in hypersensitivity of discrete mechanoreceptive neuronal subtypes. Thus, c-Kit can now be grouped with a small family of receptor tyrosine kinases, including c-Ret and TrkA, that control the transduction properties of sensory neurons.

  9. JunB transcription factor maintains skeletal muscle mass and promotes hypertrophy

    PubMed Central

    Raffaello, Anna; Milan, Giulia; Masiero, Eva; Carnio, Silvia; Lee, Donghoon

    2010-01-01

    The size of skeletal muscle cells is precisely regulated by intracellular signaling networks that determine the balance between overall rates of protein synthesis and degradation. Myofiber growth and protein synthesis are stimulated by the IGF-1/Akt/mammalian target of rapamycin (mTOR) pathway. In this study, we show that the transcription factor JunB is also a major determinant of whether adult muscles grow or atrophy. We found that in atrophying myotubes, JunB is excluded from the nucleus and that decreasing JunB expression by RNA interference in adult muscles causes atrophy. Furthermore, JunB overexpression induces hypertrophy without affecting satellite cell proliferation and stimulated protein synthesis independently of the Akt/mTOR pathway. When JunB is transfected into denervated muscles, fiber atrophy is prevented. JunB blocks FoxO3 binding to atrogin-1 and MuRF-1 promoters and thus reduces protein breakdown. Therefore, JunB is important not only in dividing populations but also in adult muscle, where it is required for the maintenance of muscle size and can induce rapid hypertrophy and block atrophy. PMID:20921137

  10. Mitochondrial Energy and Redox Signaling in Plants

    PubMed Central

    Schwarzländer, Markus

    2013-01-01

    Abstract Significance: For a plant to grow and develop, energy and appropriate building blocks are a fundamental requirement. Mitochondrial respiration is a vital source for both. The delicate redox processes that make up respiration are affected by the plant's changing environment. Therefore, mitochondrial regulation is critically important to maintain cellular homeostasis. This involves sensing signals from changes in mitochondrial physiology, transducing this information, and mounting tailored responses, by either adjusting mitochondrial and cellular functions directly or reprogramming gene expression. Recent Advances: Retrograde (RTG) signaling, by which mitochondrial signals control nuclear gene expression, has been a field of very active research in recent years. Nevertheless, no mitochondrial RTG-signaling pathway is yet understood in plants. This review summarizes recent advances toward elucidating redox processes and other bioenergetic factors as a part of RTG signaling of plant mitochondria. Critical Issues: Novel insights into mitochondrial physiology and redox-regulation provide a framework of upstream signaling. On the other end, downstream responses to modified mitochondrial function have become available, including transcriptomic data and mitochondrial phenotypes, revealing processes in the plant that are under mitochondrial control. Future Directions: Drawing parallels to chloroplast signaling and mitochondrial signaling in animal systems allows to bridge gaps in the current understanding and to deduce promising directions for future research. It is proposed that targeted usage of new technical approaches, such as quantitative in vivo imaging, will provide novel leverage to the dissection of plant mitochondrial signaling. Antioxid. Redox Signal. 18, 2122–2144. PMID:23234467

  11. Basic Fibroblast Growth Factor Activates Serum Response Factor Gene Expression by Multiple Distinct Signaling Mechanisms

    PubMed Central

    Spencer, Jeffrey A.; Major, Michael L.; Misra, Ravi P.

    1999-01-01

    Serum response factor (SRF) plays a central role in the transcriptional response of mammalian cells to a variety of extracellular signals. It is a key regulator of many cellular early response genes which are believed to be involved in cell growth and differentiation. The mechanism by which SRF activates transcription in response to mitogenic agents has been extensively studied; however, significantly less is known about regulation of the SRF gene itself. Previously, we identified distinct regulatory elements in the SRF promoter that play a role in activation, including a consensus ETS domain binding site, a consensus overlapping Sp/Egr-1 binding site, and two SRF binding sites. We further showed that serum induces SRF by a mechanism that requires an intact SRF binding site, also termed a CArG box. In the present study we demonstrate that in response to stimulation of cells by a purified growth factor, basic fibroblast growth factor (bFGF), the SRF promoter is upregulated by a complex pathway that involves at least two independent mechanisms: a CArG box-independent mechanism that is mediated by an ETS binding site, and a novel CArG box-dependent mechanism that requires both an Sp factor binding site and the CArG motifs for maximal stimulation. Our analysis indicates that the CArG/Sp element activation mechanism is mediated by distinct signaling pathways. The CArG box-dependent component is targeted by a Rho-mediated pathway, and the Sp binding site-dependent component is targeted by a Ras-mediated pathway. Both SRF and bFGF have been implicated in playing an important role in mediating cardiogenesis during development. The implications of our findings for SRF expression during development are discussed. PMID:10330138

  12. Signal functions in delayed reinforcement

    PubMed Central

    Lattal, Kennon A.

    1984-01-01

    Three experiments were conducted with pigeons to examine the role of the signal in delay-of-reinforcement procedures. In the first, a blackout accompanying a period of nonreinforcement increased key-peck response rates maintained by immediate reinforcement. The effects of dissociating the blackout from the delay interval were examined in the second experiment. In three conditions, blackouts and unsignaled delays were negatively correlated or occurred randomly with respect to one another. A signaled delay and an unsignaled delay that omitted the blackouts were studied in two other conditions. All delay-of-reinforcement conditions generally produced response rates lower than those produced by immediate reinforcement. Signaled delays maintained higher response rates than did any of the various unsignaled-delay conditions, with or without dissociated blackouts. The effects of these latter conditions did not differ systematically from one another. The final experiment showed that response rates varied as a function of the frequency with which a blackout accompanied delay intervals. By eliminating a number of methodological difficulties present in previous delay-of-reinforcement experiments, these results suggest the importance of the signal in maintaining responding during delay-of-reinforcement procedures and, conversely, the importance of the delay interval in decreasing responding. PMID:16812387

  13. TCR signaling by conventional CD4+ T cells is required for optimal maintenance of peripheral regulatory T cell numbers.

    PubMed

    Leichner, Theresa M; Satake, Atsushi; Kambayashi, Taku

    2016-06-01

    To maintain immune tolerance, regulatory T cell (Treg) numbers must be closely indexed to the number of conventional T cells (Tconvs) so that an adequate Treg:Tconv ratio can be maintained. Two factors important in this process are the cytokine interleukin-2 (IL-2) and T cell receptor (TCR) stimulation by major histocompatibility complex class II (MHC-II). Here, we report that in addition to TCR stimulation of Tregs themselves, the maintenance of Tregs also requires TCR signaling by Tconvs. We found that Tconvs produce IL-2 in response to self-peptide-MHC-II complexes and that Tconvs possessing more highly self-reactive TCRs express more IL-2 at baseline. Furthermore, selective disruption of TCR signaling in Tconvs led to a trend toward decreased expression of IL-2 and attenuated their ability to maintain Treg numbers. These data suggest that in order to maintain an adequate Treg:Tconv ratio, Tregs are continuously indexed to self-peptide-MHC-II-induced TCR signaling of Tconvs. These results have implications in attempts to modulate immune tolerance, as Treg numbers adjust to the self-reactivity, and ultimately IL-2 production by the T cells around them.

  14. β-catenin-mediated Wnt signaling regulates neurogenesis in the ventral telencephalon

    PubMed Central

    Gulacsi, Alexandra A.; Anderson, Stewart A.

    2009-01-01

    Development of the telencephalon involves the coordinated growth of diversely patterned brain structures. Previous studies have demonstrated the importance of β-catenin-mediated Wnt signaling in proliferation and fate determination during cerebral cortical development. In this paper, we present novel evidence that β-catenin-mediated Wnt signaling also critically maintains progenitor proliferation in the subcortical (pallidal) telencephalon of mice. Targeted deletion of β-catenin severely impairs proliferation in the medial ganglionic eminence without grossly altering differentiated fate. Several lines of evidence suggest that this phenotype is primarily due to loss of canonical Wnt signaling. As previous studies have suggested that the ventral patterning factor Shh also stimulates dorsal telencephalic proliferation, we propose a model whereby Wnt and Shh signaling promote distinct dorsal-ventral patterning, while also having broader effects on proliferation that serve to coordinate the growth of telencephalic subregions. PMID:18997789

  15. The role of tumour necrosis factor-α and tumour necrosis factor receptor signalling in inflammation-associated systemic genotoxicity

    PubMed Central

    Westbrook, Aya M.; Wei, Bo; Hacke, Katrin; Xia, Menghang; Braun, Jonathan; Schiestl, Robert H.

    2012-01-01

    Chronic inflammatory diseases are characterised by systemically elevated levels of tumour necrosis factor (TNF)-α, a proinflammatory cytokine with pleiotropic downstream effects. We have previously demonstrated increased genotoxicity in peripheral leukocytes and various tissues in models of intestinal inflammation. In the present study, we asked whether TNF-α is sufficient to induce DNA damage systemically, as observed in intestinal inflammation, and whether tumour necrosis factor receptor (TNFR) signalling would be necessary for the resultant genotoxicity. In the wild-type mice, 500 ng per mouse of TNF-α was sufficient to induce DNA damage to multiple cell types and organs 1-h post-administration. Primary splenic T cells manifested TNF-α-induced DNA damage in the absence of other cell types. Furthermore, TNFR1−/−TNFR2−/− mice demonstrated decreased systemic DNA damage in a model of intestinal inflammation and after TNF-α injection versus wild-type mice, indicating the necessity of TNFR signalling. Nuclear factor (NF)-κB inhibitors were also able to decrease damage induced by TNF-α injection in wild-type mice. When TNF-α administration was combined with interleukin (IL)-1β, another proinflammatory cytokine, DNA damage persisted for up to 24 h. When combined with IL-10, an anti-inflammatory cytokine, decreased genotoxicity was observed in vivo and in vitro. TNF-α/TNFR-mediated signalling is therefore sufficient and plays a large role in mediating DNA damage to various cell types, subject to modulation by other cytokines and their mediators. PMID:21980144

  16. Adenosine and Hypoxia-Inducible Factor Signaling in Intestinal Injury and Recovery

    PubMed Central

    Eltzschig, Holger K.

    2013-01-01

    The gastrointestinal mucosa has proven to be an interesting tissue in which to investigate disease-related metabolism. In this review, we outline some of the evidence that implicates hypoxia-mediated adenosine signaling as an important signature within both healthy and diseased mucosa. Studies derived from cultured cell systems, animal models, and human patients have revealed that hypoxia is a significant component of the inflammatory microenvironment. These studies have revealed a prominent role for hypoxia-induced factor (HIF) and hypoxia signaling at several steps along the adenine nucleotide metabolism and adenosine receptor signaling pathways. Likewise, studies to date in animal models of intestinal inflammation have demonstrated an almost uniformly beneficial influence of HIF stabilization on disease outcomes. Ongoing studies to define potential similarities with and differences between innate and adaptive immune responses will continue to teach us important lessons about the complexity of the gastrointestinal tract. Such information has provided new insights into disease pathogenesis and, importantly, will provide insights into new therapeutic targets. PMID:21942704

  17. Fibroblast growth factor (Fgf) signaling pathway regulates liver homeostasis in zebrafish.

    PubMed

    Tsai, Su-Mei; Liu, Da-Wei; Wang, Wen-Pin

    2013-04-01

    In mammals, fibroblast growth factor (FGF) signaling controls liver specification and regulates the metabolism of lipids, cholesterol, and bile acids. FGF signaling also promotes hepatocyte proliferation, and helps detoxify hepatotoxin during liver regeneration after partial hepatectomy. However, the function of Fgf in zebrafish liver is not yet well understood, specifically for postnatal homeostasis. The current study analyzed the expression of fgf receptors (fgfrs) in the liver of zebrafish. We then investigated the function of Fgf signaling in the zebrafish liver by expressing a dominant-negative Fgf receptor in hepatocytes (lfabp:dnfgfr1-egfp, lf:dnfr). Histological analysis showed that our genetic intervention resulted in a small liver size with defected medial expansion of developing livers in transgenic (Tg) larvae. Morphologically, the liver lobe of lf:dnfr adult fish was shorter than that of control. Ballooning degeneration of hepatocytes was observed in fish as young as 3 months. Further examination revealed the development of hepatic steatosis and cholestasis. In adult Tg fish, we unexpectedly observed increased liver-to-body-weight ratios, with higher percentages of proliferating hepatocytes. Considering all these findings, we concluded that as in mammals, in adult zebrafish the metabolism of lipid and bile acids in the liver are regulated by Fgf signaling. Disruption of the Fgf signal-mediated metabolism might indirectly affect hepatocyte proliferation.

  18. Intracellular mediators of transforming growth factor beta superfamily signaling localize to endosomes in chicken embryo and mouse lenses in vivo.

    PubMed

    Rajagopal, Ramya; Ishii, Shunsuke; Beebe, David C

    2007-06-25

    Endocytosis is a key regulator of growth factor signaling pathways. Recent studies showed that the localization to endosomes of intracellular mediators of growth factor signaling may be required for their function. Although there is substantial evidence linking endocytosis and growth factor signaling in cultured cells, there has been little study of the endosomal localization of signaling components in intact tissues or organs. Proteins that are downstream of the transforming growth factor-beta superfamily signaling pathway were found on endosomes in chicken embryo and postnatal mouse lenses, which depend on signaling by members of the TGFbeta superfamily for their normal development. Phosphorylated Smad1 (pSmad1), pSmad2, Smad4, Smad7, the transcriptional repressors c-Ski and TGIF and the adapter molecules Smad anchor for receptor activation (SARA) and C184M, localized to EEA-1- and Rab5-positive vesicles in chicken embryo and/or postnatal mouse lenses. pSmad1 and pSmad2 also localized to Rab7-positive late endosomes. Smad7 was found associated with endosomes, but not caveolae. Bmpr1a conditional knock-out lenses showed decreased nuclear and endosomal localization of pSmad1. Many of the effectors in this pathway were distributed differently in vivo from their reported distribution in cultured cells. Based on the findings reported here and data from other signaling systems, we suggest that the localization of activated intracellular mediators of the transforming growth factor-beta superfamily to endosomes is important for the regulation of growth factor signaling.

  19. The Effect of α-Mating Factor Secretion Signal Mutations on Recombinant Protein Expression in Pichia pastoris

    PubMed Central

    Lin-Cereghino, Geoff P.; Stark, Carolyn M.; Kim, Daniel; Chang, Jennifer; Shaheen, Nadia; Poerwanto, Hansel; Agari, Kimiko; Moua, Pachai; Low, Lauren K.; Tran, Namphuong; Huang, Amy D.; Nattestad, Maria; Oshiro, Kristin T.; Chang, John William; Chavan, Archana; Tsai, Jerry W.; Lin-Cereghino, Joan

    2013-01-01

    The methylotrophic yeast, Pichia pastoris, has been genetically engineered to produce many heterologous proteins for industrial and research purposes. In order to secrete proteins for easier purification from the extracellular medium, the coding sequence of recombinant proteins are initially fused to the Saccharomyces cerevisiae α-mating factor secretion signal leader. Extensive site-directed mutagenesis of the prepro region of the α-mating factor secretion signal sequence was performed in order to determine the effects of various deletions and substitutions on expression. Though some mutations clearly dampened protein expression, deletion of amino acids 57-70, corresponding to the predicted 3rd alpha helix of α-mating factor secretion signal, increased secretion of reporter proteins horseradish peroxidase and lipase at least 50% in small-scale cultures. These findings raise the possibility that the secretory efficiency of the leader can be further enhanced in the future. PMID:23454485

  20. Nanoconjugation prolongs endosomal signaling of the epidermal growth factor receptor and enhances apoptosis

    NASA Astrophysics Data System (ADS)

    Wu, L.; Xu, F.; Reinhard, B. M.

    2016-07-01

    It is becoming increasingly clear that intracellular signaling can be subject to strict spatial control. As the covalent attachment of a signaling ligand to a nanoparticle (NP) impacts ligand-receptor binding, uptake, and trafficking, nanoconjugation provides new opportunities for manipulating intracellular signaling in a controlled fashion. To establish the effect of nanoconjugation on epidermal growth factor (EGF) mediated signaling, we investigate here the intracellular fate of nanoconjugated EGF (NP-EGF) and its bound receptor (EGFR) by quantitative correlated darkfield/fluorescence microscopy and density-based endosomal fractionation. We demonstrate that nanoconjugation prolongs the dwell time of phosphorylated receptors in the early endosomes and that the retention of activated EGFR in the early endosomes is accompanied by an EGF mediated apoptosis at effective concentrations that do not induce apoptosis in the case of free EGF. Overall, these findings indicate nanoconjugation as a rational strategy for modifying signaling that acts by modulating the temporo-spatial distribution of the activated EGF-EGFR ligand-receptor complex.It is becoming increasingly clear that intracellular signaling can be subject to strict spatial control. As the covalent attachment of a signaling ligand to a nanoparticle (NP) impacts ligand-receptor binding, uptake, and trafficking, nanoconjugation provides new opportunities for manipulating intracellular signaling in a controlled fashion. To establish the effect of nanoconjugation on epidermal growth factor (EGF) mediated signaling, we investigate here the intracellular fate of nanoconjugated EGF (NP-EGF) and its bound receptor (EGFR) by quantitative correlated darkfield/fluorescence microscopy and density-based endosomal fractionation. We demonstrate that nanoconjugation prolongs the dwell time of phosphorylated receptors in the early endosomes and that the retention of activated EGFR in the early endosomes is accompanied by an EGF

  1. A pathway to bone: signaling molecules and transcription factors involved in chondrocyte development and maturation

    PubMed Central

    Kozhemyakina, Elena; Lassar, Andrew B.; Zelzer, Elazar

    2015-01-01

    Decades of work have identified the signaling pathways that regulate the differentiation of chondrocytes during bone formation, from their initial induction from mesenchymal progenitor cells to their terminal maturation into hypertrophic chondrocytes. Here, we review how multiple signaling molecules, mechanical signals and morphological cell features are integrated to activate a set of key transcription factors that determine and regulate the genetic program that induces chondrogenesis and chondrocyte differentiation. Moreover, we describe recent findings regarding the roles of several signaling pathways in modulating the proliferation and maturation of chondrocytes in the growth plate, which is the ‘engine’ of bone elongation. PMID:25715393

  2. Both internalization and AIP1 association are required for tumor necrosis factor receptor 2-mediated JNK signaling.

    PubMed

    Ji, Weidong; Li, Yonghao; Wan, Ting; Wang, Jing; Zhang, Haifeng; Chen, Hong; Min, Wang

    2012-09-01

    The proinflammtory cytokine tumor necrosis factor (TNF), primarily via TNF receptor 1 (TNFR1), induces nuclear factor-κB (NF-κB)-dependent cell survival, and c-Jun N-terminal kinase (JNK) and caspase-dependent cell death, regulating vascular endothelial cell (EC) activation and apoptosis. However, signaling by the second receptor, TNFR2, is poorly understood. The goal of this study was to dissect how TNFR2 mediates NF-κB and JNK signaling in vascular EC, and its relevance to in vivo EC function. We show that TNFR2 contributes to TNF-induced NF-κB and JNK signaling in EC as TNFR2 deletion or knockdown reduces the TNF responses. To dissect the critical domains of TNFR2 that mediate the TNF responses, we examine the activity of TNFR2 mutant with a specific deletion of the TNFR2 intracellular region, which contains conserved domain I, domain II, domain III, and 2 TNFR-associated factor-2-binding sites. Deletion analyses indicate that different sequences on TNFR2 have distinct roles in NF-κB and JNK activation. Specifically, deletion of the TNFR-associated factor-2-binding sites (TNFR2-59) diminishes the TNFR2-mediated NF-κB, but not JNK activation; whereas, deletion of domain II or domain III blunts TNFR2-mediated JNK but not NF-κB activation. Interestingly, we find that the TNFR-associated factor-2-binding sites ensure TNFR2 on the plasma membrane, but the di-leucine LL motif within the domain II and aa338-355 within the domain III are required for TNFR2 internalization as well as TNFR2-dependent JNK signaling. Moreover, domain III of TNFR2 is responsible for association with ASK1-interacting protein-1, a signaling adaptor critical for TNF-induced JNK signaling. While TNFR2 containing the TNFR-associated factor-2-binding sites prevents EC cell death, a specific activation of JNK without NF-κB activation by TNFR2-59 strongly induces caspase activation and EC apoptosis. Our data reveal that both internalization and ASK1-interacting protein-1 association are

  3. FOXOs attenuate bone formation by suppressing Wnt signaling

    PubMed Central

    Iyer, Srividhya; Ambrogini, Elena; Bartell, Shoshana M.; Han, Li; Roberson, Paula K.; de Cabo, Rafael; Jilka, Robert L.; Weinstein, Robert S.; O’Brien, Charles A.; Manolagas, Stavros C.; Almeida, Maria

    2013-01-01

    Wnt/β-catenin/TCF signaling stimulates bone formation and suppresses adipogenesis. The hallmarks of skeletal involution with age, on the other hand, are decreased bone formation and increased bone marrow adiposity. These changes are associated with increased oxidative stress and decreased growth factor production, which activate members of the FOXO family of transcription factors. FOXOs in turn attenuate Wnt/β-catenin signaling by diverting β-catenin from TCF- to FOXO-mediated transcription. We show herein that mice lacking Foxo1, -3, and -4 in bipotential progenitors of osteoblast and adipocytes (expressing Osterix1) exhibited increased osteoblast number and high bone mass that was maintained in old age as well as decreased adiposity in the aged bone marrow. The increased bone mass in the Foxo-deficient mice was accounted for by increased proliferation of osteoprogenitor cells and bone formation resulting from upregulation of Wnt/β-catenin signaling and cyclin D1 expression, but not changes in redox balance. Consistent with this mechanism, β-catenin deletion in Foxo null cells abrogated both the increased cyclin D1 expression and proliferation. The elucidation of a restraining effect of FOXOs on Wnt signaling in bipotential progenitors suggests that FOXO activation by accumulation of age-associated cellular stressors may be a seminal pathogenetic mechanism in the development of involutional osteoporosis. PMID:23867625

  4. Comparative biology of sperm factors and fertilization-induced calcium signals across the animal kingdom.

    PubMed

    Kashir, Junaid; Deguchi, Ryusaku; Jones, Celine; Coward, Kevin; Stricker, Stephen A

    2013-10-01

    Fertilization causes mature oocytes or eggs to increase their concentrations of intracellular calcium ions (Ca²⁺) in all animals that have been examined, and such Ca²⁺ elevations, in turn, provide key activating signals that are required for non-parthenogenetic development. Several lines of evidence indicate that the Ca²⁺ transients produced during fertilization in mammals and other taxa are triggered by soluble factors that sperm deliver into oocytes after gamete fusion. Thus, for a broad-based analysis of Ca²⁺ dynamics during fertilization in animals, this article begins by summarizing data on soluble sperm factors in non-mammalian species, and subsequently reviews various topics related to a sperm-specific phospholipase C, called PLCζ, which is believed to be the predominant activator of mammalian oocytes. After characterizing initiation processes that involve sperm factors or alternative triggering mechanisms, the spatiotemporal patterns of Ca²⁺ signals in fertilized oocytes or eggs are compared in a taxon-by-taxon manner, and broadly classified as either a single major transient or a series of repetitive oscillations. Both solitary and oscillatory types of fertilization-induced Ca²⁺ signals are typically propagated as global waves that depend on Ca²⁺ release from the endoplasmic reticulum in response to increased concentrations of inositol 1,4,5-trisphosphate (IP₃). Thus, for taxa where relevant data are available, upstream pathways that elevate intraoocytic IP3 levels during fertilization are described, while other less-common modes of producing Ca²⁺ transients are also examined. In addition, the importance of fertilization-induced Ca²⁺ signals for activating development is underscored by noting some major downstream effects of these signals in various animals. © 2013 Wiley Periodicals, Inc.

  5. Integration of light and circadian signals that regulate chloroplast transcription by a nuclear-encoded sigma factor.

    PubMed

    Belbin, Fiona E; Noordally, Zeenat B; Wetherill, Sarah J; Atkins, Kelly A; Franklin, Keara A; Dodd, Antony N

    2017-01-01

    We investigated the signalling pathways that regulate chloroplast transcription in response to environmental signals. One mechanism controlling plastid transcription involves nuclear-encoded sigma subunits of plastid-encoded plastid RNA polymerase. Transcripts encoding the sigma factor SIG5 are regulated by light and the circadian clock. However, the extent to which a chloroplast target of SIG5 is regulated by light-induced changes in SIG5 expression is unknown. Moreover, the photoreceptor signalling pathways underlying the circadian regulation of chloroplast transcription by SIG5 are unidentified. We monitored the regulation of chloroplast transcription in photoreceptor and sigma factor mutants under controlled light regimes in Arabidopsis thaliana. We established that a chloroplast transcriptional response to light intensity was mediated by SIG5; a chloroplast transcriptional response to the relative proportions of red and far red light was regulated by SIG5 through phytochrome and photosynthetic signals; and the circadian regulation of chloroplast transcription by SIG5 was predominantly dependent on blue light and cryptochrome. Our experiments reveal the extensive integration of signals concerning the light environment by a single sigma factor to regulate chloroplast transcription. This may originate from an evolutionarily ancient mechanism that protects photosynthetic bacteria from high light stress, which subsequently became integrated with higher plant phototransduction networks. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  6. Structural basis for signal recognition and transduction by platelet-activating-factor receptor.

    PubMed

    Cao, Can; Tan, Qiuxiang; Xu, Chanjuan; He, Lingli; Yang, Linlin; Zhou, Ye; Zhou, Yiwei; Qiao, Anna; Lu, Minmin; Yi, Cuiying; Han, Gye Won; Wang, Xianping; Li, Xuemei; Yang, Huaiyu; Rao, Zihe; Jiang, Hualiang; Zhao, Yongfang; Liu, Jianfeng; Stevens, Raymond C; Zhao, Qiang; Zhang, Xuejun C; Wu, Beili

    2018-06-01

    Platelet-activating-factor receptor (PAFR) responds to platelet-activating factor (PAF), a phospholipid mediator of cell-to-cell communication that exhibits diverse physiological effects. PAFR is considered an important drug target for treating asthma, inflammation and cardiovascular diseases. Here we report crystal structures of human PAFR in complex with the antagonist SR 27417 and the inverse agonist ABT-491 at 2.8-Å and 2.9-Å resolution, respectively. The structures, supported by molecular docking of PAF, provide insights into the signal-recognition mechanisms of PAFR. The PAFR-SR 27417 structure reveals an unusual conformation showing that the intracellular tips of helices II and IV shift outward by 13 Å and 4 Å, respectively, and helix VIII adopts an inward conformation. The PAFR structures, combined with single-molecule FRET and cell-based functional assays, suggest that the conformational change in the helical bundle is ligand dependent and plays a critical role in PAFR activation, thus greatly extending knowledge about signaling by G-protein-coupled receptors.

  7. Role of IGF-I Signaling in Muscle Bone Interactions

    PubMed Central

    Bikle, Daniel D; Tahimic, Candice; Chang, Wenhan; Wang, Yongmei; Philippou, Anastassios; Barton, Elisabeth R.

    2015-01-01

    Skeletal muscle and bone rely on a number of growth factors to undergo development, modulate growth, and maintain physiological strength. A major player in these actions is insulin-like growth factor I (IGF-I). However, because this growth factor can directly enhance muscle mass and bone density, it alters the state of the musculoskeletal system indirectly through mechanical crosstalk between these two organ systems. Thus, there are clearly synergistic actions of IGF-I that extend beyond the direct activity through its receptor. This review will cover the production and signaling of IGF-I as it pertains to muscle and bone, the chemical and mechanical influences that arise from IGF-I activity, and the potential for therapeutic strategies based on IGF-I. PMID:26453498

  8. Neutron Detector Signal Processing to Calculate the Effective Neutron Multiplication Factor of Subcritical Assemblies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Talamo, Alberto; Gohar, Yousry

    2016-06-01

    This report describes different methodologies to calculate the effective neutron multiplication factor of subcritical assemblies by processing the neutron detector signals using MATLAB scripts. The subcritical assembly can be driven either by a spontaneous fission neutron source (e.g. californium) or by a neutron source generated from the interactions of accelerated particles with target materials. In the latter case, when the particle accelerator operates in a pulsed mode, the signals are typically stored into two files. One file contains the time when neutron reactions occur and the other contains the times when the neutron pulses start. In both files, the timemore » is given by an integer representing the number of time bins since the start of the counting. These signal files are used to construct the neutron count distribution from a single neutron pulse. The built-in functions of MATLAB are used to calculate the effective neutron multiplication factor through the application of the prompt decay fitting or the area method to the neutron count distribution. If the subcritical assembly is driven by a spontaneous fission neutron source, then the effective multiplication factor can be evaluated either using the prompt neutron decay constant obtained from Rossi or Feynman distributions or the Modified Source Multiplication (MSM) method.« less

  9. Hedgehog signaling regulates segment formation in the annelid Platynereis.

    PubMed

    Dray, Nicolas; Tessmar-Raible, Kristin; Le Gouar, Martine; Vibert, Laura; Christodoulou, Foteini; Schipany, Katharina; Guillou, Aurélien; Zantke, Juliane; Snyman, Heidi; Béhague, Julien; Vervoort, Michel; Arendt, Detlev; Balavoine, Guillaume

    2010-07-16

    Annelids and arthropods share a similar segmented organization of the body whose evolutionary origin remains unclear. The Hedgehog signaling pathway, prominent in arthropod embryonic segment patterning, has not been shown to have a similar function outside arthropods. We show that the ligand Hedgehog, the receptor Patched, and the transcription factor Gli are all expressed in striped patterns before the morphological appearance of segments in the annelid Platynereis dumerilii. Treatments with small molecules antagonistic to Hedgehog signaling disrupt segment formation. Platynereis Hedgehog is not necessary to establish early segment patterns but is required to maintain them. The molecular similarity of segment patterning functions of the Hedgehog pathway in an annelid and in arthropods supports a common origin of segmentation in protostomes.

  10. [The role of Smads and related transcription factors in the signal transduction of bone morphogenetic protein inducing bone formation].

    PubMed

    Xu, Xiao-liang; Dai, Ke-rong; Tang, Ting-ting

    2003-09-01

    To clarify the mechanisms of the signal transduction of bone morphogenetic proteins (BMPs) inducing bone formation and to provide theoretical basis for basic and applying research of BMPs. We looked up the literature of the role of Smads and related transcription factors in the signal transduction of BMPs inducing bone formation. The signal transduction processes of BMPs included: 1. BMPs combined with type II and type I receptors; 2. the type I receptor phosphorylated Smads; and 3. Smads entered the cell nucleus, interacted with transcription factors and influenced the transcription of related proteins. Smads could be divided into receptor-regulated Smads (R-Smads: Smad1, Smad2, Smad3, Smad5, Smad8 and Smad9), common-mediator Smad (co-Smad: Smad4), and inhibitory Smads (I-Smads: Smad6 and Smad7). Smad1, Smad5, Smad8, and probable Smad9 were involved in the signal transduction of BMPs. Multiple kinases, such as focal adhesion kinase (FAK), Ras-extracellular signal-regulated kinase (ERK), phosphatidylinositol 3-kinase (PI3K), and Akt serine/threonine kinase were related to Smads signal transduction. Smad1 and Smad5 related with transcription factors included core binding factor A1 (CBFA1), smad-interacting protein 1 (SIP1), ornithine decarboxylase antizyme (OAZ), activating protein-1 (AP-1), xenopus ventralizing homeobox protein-2 (Xvent-2), sandostatin (Ski), antiproliferative proteins (Tob), and homeodomain-containing transcriptian factor-8 (Hoxc-8), et al. CBFA1 could interact with Smad1, Smad2, Smad3, and Smad5, so it was involved in TGF-beta and BMP-2 signal transduction, and played an important role in the bone formation. Cleidocranial dysplasia (CCD) was thought to be caused by heterozygous mutations in CBFA1. The CBFA1 knockout mice showed no osteogenesis and had maturational disturbance of chondrocytes. Smads and related transcription factors, especially Smad1, Smad5, Smad8 and CBFA1, play an important role in the signal transduction of BMPs inducing bone

  11. The leukemia-associated Rho guanine nucleotide exchange factor LARG is required for efficient replication stress signaling

    PubMed Central

    Beveridge, Ryan D; Staples, Christopher J; Patil, Abhijit A; Myers, Katie N; Maslen, Sarah; Skehel, J Mark; Boulton, Simon J; Collis, Spencer J

    2014-01-01

    We previously identified and characterized TELO2 as a human protein that facilitates efficient DNA damage response (DDR) signaling. A subsequent yeast 2-hybrid screen identified LARG; Leukemia-Associated Rho Guanine Nucleotide Exchange Factor (also known as Arhgef12), as a potential novel TELO2 interactor. LARG was previously shown to interact with Pericentrin (PCNT), which, like TELO2, is required for efficient replication stress signaling. Here we confirm interactions between LARG, TELO2 and PCNT and show that a sub-set of LARG co-localizes with PCNT at the centrosome. LARG-deficient cells exhibit replication stress signaling defects as evidenced by; supernumerary centrosomes, reduced replication stress-induced γH2AX and RPA nuclear foci formation, and reduced activation of the replication stress signaling effector kinase Chk1 in response to hydroxyurea. As such, LARG-deficient cells are sensitive to replication stress-inducing agents such as hydroxyurea and mitomycin C. Conversely we also show that depletion of TELO2 and the replication stress signaling kinase ATR leads to RhoA signaling defects. These data therefore reveal a level of crosstalk between the RhoA and DDR signaling pathways. Given that mutations in both ATR and PCNT can give rise to the related primordial dwarfism disorders of Seckel Syndrome and Microcephalic osteodysplastic primordial dwarfism type II (MOPDII) respectively, which both exhibit defects in ATR-dependent checkpoint signaling, these data also raise the possibility that mutations in LARG or disruption to RhoA signaling may be contributory factors to the etiology of a sub-set of primordial dwarfism disorders. PMID:25485589

  12. Density and Duration of Pneumococcal Carriage Is Maintained by Transforming Growth Factor β1 and T Regulatory Cells

    PubMed Central

    Coward, William R.; Gritzfeld, Jenna F.; Richards, Luke; Garcia-Garcia, Francesc J.; Dotor, Javier; Gordon, Stephen B.

    2014-01-01

    Rationale: Nasopharyngeal carriage of Streptococcus pneumoniae is a prerequisite for invasive disease, but the majority of carriage episodes are asymptomatic and self-resolving. Interactions determining the development of carriage versus invasive disease are poorly understood but will influence the effectiveness of vaccines or therapeutics that disrupt nasal colonization. Objectives: We sought to elucidate immunological mechanisms underlying noninvasive pneumococcal nasopharyngeal carriage. Methods: Pneumococcal interactions with human nasopharyngeal and bronchial fibroblasts and epithelial cells were investigated in vitro. A murine model of nasopharyngeal carriage and an experimental human pneumococcal challenge model were used to characterize immune responses in the airways during carriage. Measurements and Main Results: We describe the previously unknown immunological basis of noninvasive carriage and highlight mechanisms whose perturbation may lead to invasive disease. We identify the induction of active transforming growth factor (TGF)-β1 by S. pneumoniae in human host cells and highlight the key role for TGF-β1 and T regulatory cells in the establishment and maintenance of nasopharyngeal carriage in mice and humans. We identify the ability of pneumococci to drive TGF-β1 production from nasopharyngeal cells in vivo and show that an immune tolerance profile, characterized by elevated TGF-β1 and high nasopharyngeal T regulatory cell numbers, is crucial for prolonged carriage of pneumococci. Blockade of TGF-β1 signaling prevents prolonged carriage and leads to clearance of pneumococci from the nasopharynx. Conclusions: These data explain the mechanisms by which S. pneumoniae colonize the human nasopharynx without inducing damaging host inflammation and provide insight into the role of bacterial and host constituents that allow and maintain carriage. PMID:24749506

  13. Chordin and dickkopf-1b are essential for the formation of head structures through activation of the FGF signaling pathway in zebrafish.

    PubMed

    Tanaka, Shingo; Hosokawa, Hiroshi; Weinberg, Eric S; Maegawa, Shingo

    2017-04-15

    The ability of the Spemann organizer to induce dorsal axis formation is dependent on downstream factors of the maternal Wnt/β-catenin signaling pathway. The fibroblast growth factor (FGF) signaling pathway has been identified as one of the downstream components of the maternal Wnt/β-catenin signaling pathway. The ability of the FGF signaling pathway to induce the formation of a dorsal axis with a complete head structure requires chordin (chd) expression; however, the molecular mechanisms involved in this developmental process, due to activation of FGF signaling, remain unclear. In this study, we showed that activation of the FGF signaling pathway induced the formation of complete head structures through the expression of chd and dickkopf-1b (dkk1b). Using the organizer-deficient maternal mutant, ichabod, we identified dkk1b as a novel downstream factor in the FGF signaling pathway. We also demonstrate that dkk1b expression is necessary, after activation of the FGF signaling pathway, to induce neuroectoderm patterning along the anteroposterior (AP) axis and for formation of complete head structures. Co-injection of chd and dkk1b mRNA resulted in the formation of a dorsal axis with a complete head structure in ichabod embryos, confirming the role of these factors in this developmental process. Unexpectedly, we found that chd induced dkk1b expression in ichabod embryos at the shield stage. However, chd failed to maintain dkk1b expression levels in cells of the shield and, subsequently, in the cells of the prechordal plate after mid-gastrula stage. In contrast, activation of the FGF signaling pathway maintained the dkk1b expression from the beginning of gastrulation to early somitogenesis. In conclusion, activation of the FGF signaling pathway induces the formation of a dorsal axis with a complete head structure through the expression of chd and subsequent maintenance of dkk1b expression levels. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Wnt and FGF signals interact to coordinate growth with cell fate specification during limb development.

    PubMed

    ten Berge, Derk; Brugmann, Samantha A; Helms, Jill A; Nusse, Roel

    2008-10-01

    A fundamental question in developmental biology is how does an undifferentiated field of cells acquire spatial pattern and undergo coordinated differentiation? The development of the vertebrate limb is an important paradigm for understanding these processes. The skeletal and connective tissues of the developing limb all derive from a population of multipotent progenitor cells located in its distal tip. During limb outgrowth, these progenitors segregate into a chondrogenic lineage, located in the center of the limb bud, and soft connective tissue lineages located in its periphery. We report that the interplay of two families of signaling proteins, fibroblast growth factors (FGFs) and Wnts, coordinate the growth of the multipotent progenitor cells with their simultaneous segregation into these lineages. FGF and Wnt signals act together to synergistically promote proliferation while maintaining the cells in an undifferentiated, multipotent state, but act separately to determine cell lineage specification. Withdrawal of both signals results in cell cycle withdrawal and chondrogenic differentiation. Continued exposure to Wnt, however, maintains proliferation and re-specifies the cells towards the soft connective tissue lineages. We have identified target genes that are synergistically regulated by Wnts and FGFs, and show how these factors actively suppress differentiation and promote growth. Finally, we show how the spatial restriction of Wnt and FGF signals to the limb ectoderm, and to a specialized region of it, the apical ectodermal ridge, controls the distribution of cell behaviors within the growing limb, and guides the proper spatial organization of the differentiating tissues.

  15. Signaling-Dependent Control of Apical Membrane Size and Self-Renewal in Rosette-Stage Human Neuroepithelial Stem Cells.

    PubMed

    Medelnik, Jan-Philip; Roensch, Kathleen; Okawa, Satoshi; Del Sol, Antonio; Chara, Osvaldo; Mchedlishvili, Levan; Tanaka, Elly M

    2018-06-05

    In the developing nervous system, neural stem cells are polarized and maintain an apical domain facing a central lumen. The presence of apical membrane is thought to have a profound influence on maintaining the stem cell state. With the onset of neurogenesis, cells lose their polarization, and the concomitant loss of the apical domain coincides with a loss of the stem cell identity. Little is known about the molecular signals controlling apical membrane size. Here, we use two neuroepithelial cell systems, one derived from regenerating axolotl spinal cord and the other from human embryonic stem cells, to identify a molecular signaling pathway initiated by lysophosphatidic acid that controls apical membrane size and consequently controls and maintains epithelial organization and lumen size in neuroepithelial rosettes. This apical domain size increase occurs independently of effects on proliferation and involves a serum response factor-dependent transcriptional induction of junctional and apical membrane components. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

  16. Changes in insulin-like growth factor signaling alter phenotypes in Fragile X Mice.

    PubMed

    Wise, T L

    2017-02-01

    Fragile X syndrome (FXS) is an inherited form of intellectual disability that is usually caused by expansion of a polymorphic CGG repeat in the 5' untranslated region of the X-linked FMR1 gene, which leads to hypermethylation and transcriptional silencing. Two non-neurological phenotypes of FXS are enlarged testes and connective tissue dysplasia, which could be caused by alterations in a growth factor signaling pathway. FXS patients also frequently have autistic-like symptoms, suggesting that the signaling pathways affected in FXS may overlap with those affected in autism. Identifying these pathways is important for both understanding the effects of FMR1 inactivation and developing treatments for both FXS and autism. Here we show that decreasing the levels of the insulin-like growth factor (Igf) receptor 1 corrects a number of phenotypes in the mouse model of FXS, including macro-orchidism, and that increasing the levels of IGF2 exacerbates the seizure susceptibility phenotype. These results suggest that the pathways altered by the loss of the FMR1-encoded protein (FMRP) may overlap with the pathways affected by changes in Igf signaling or that one or more of the proteins that play a role in Igf signaling could interact with FMRP. They also indicate a new set of potential targets for drug treatment of FXS and autism spectrum disorders. © 2016 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

  17. Vitamin D cell signalling in health and disease.

    PubMed

    Berridge, Michael J

    2015-04-24

    Vitamin D deficiency has been linked to many human diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), hypertension and cardiovascular disease. A Vitamin D phenotypic stability hypothesis, which is developed in this review, attempts to describe how this vital hormone acts to maintain healthy cellular functions. This role of Vitamin D as a guardian of phenotypic stability seems to depend on its ability to maintain the redox and Ca(2+) signalling systems. It is argued that its primary action is to maintain the expression of those signalling components responsible for stabilizing the low resting state of these two signalling pathways. This phenotypic stability role is facilitated through the ability of vitamin D to increase the expression of both Nrf2 and the anti-ageing protein Klotho, which are also major regulators of Ca(2+) and redox signalling. A decline in Vitamin D levels will lead to a decline in the stability of this regulatory signalling network and may account for why so many of the major diseases in man, which have been linked to vitamin D deficiency, are associated with a dysregulation in both ROS and Ca(2+) signalling. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Equine grass sickness in Scotland: a case-control study of signalment- and meteorology-related risk factors.

    PubMed

    Wylie, C E; Shaw, D J; Fordyce, F M; Lilly, A; McGorum, B C

    2014-01-01

    Equine grass sickness (EGS) remains a frequently fatal disease of equids in Britain. Since previous investigations of signalment- and meteorology-related risk factors for EGS have yielded some conflicting data, further investigation is warranted. To identify signalment- and meteorology-related risk factors for EGS in Scotland. Retrospective time-matched case-control study. This study was undertaken using data for 455 EGS cases and 910 time-matched controls that were referred to the Royal (Dick) School of Veterinary Studies, and average UK Meteorological Office weather station meteorological values from the month of admission of the animal, from the 3, 6 and 12 months prior to admission, and for the entire 1990-2006 period. Signalment-related risk factors associated with an increased risk of EGS were native Scottish pure breeds compared with crossbreeds (odds ratio [OR] = 3.56, 95% confidence interval [CI] 2.43-5.43) and animals living on premises located further north within the study region (OR = 1.08, 95% CI 1.06-1.10). There was a decreased risk of EGS in animals aged 11-20 years compared with animals 2-10 years (OR = 0.32, 95% CI 0.22-0.45), non-native Scottish pure breeds compared with crossbreeds (OR = 0.71, 95% CI 0.54-0.94), and stallions compared with mares (OR = 0.43, 95% CI 0.22-0.86). Meteorology-related risk factors associated with an increased risk of EGS were (if Ordnance Survey northing is excluded) more sun hours (OR>1.43) and more frost days (OR>1.13), while there was a decreased risk of EGS with higher average maximum temperature (OR<0.83). The signalment-related risk factors will help owners identify high-risk animals, thereby allowing them to prioritise management strategies. The identification of meteorological risk factors may assist studies on the aetiology of EGS. © 2013 EVJ Ltd.

  19. Kit signaling inhibits the sphingomyelin-ceramide pathway through PLC gamma 1: implication in stem cell factor radioprotective effect.

    PubMed

    Maddens, Stéphane; Charruyer, Alexandra; Plo, Isabelle; Dubreuil, Patrice; Berger, Stuart; Salles, Bernard; Laurent, Guy; Jaffrézou, Jean-Pierre

    2002-08-15

    Previous studies demonstrated that Kit activation confers radioprotection. However, the mechanism by which Kit signaling interferes with cellular response to ionizing radiation (IR) has not been firmly established. Based on the role of the sphingomyelin (SM) cycle apoptotic pathway in IR-induced apoptosis, we hypothesized that one of the Kit signaling components might inhibit IR-induced ceramide production or ceramide-induced apoptosis. Results show that, in both Ba/F3 and 32D murine cell lines transfected with wild-type c-kit, stem cell factor (SCF) stimulation resulted in a significant reduction of IR-induced apoptosis and cytotoxicity, whereas DNA repair remained unaffected. Moreover, SCF stimulation inhibited IR-induced neutral sphingomyelinase (N-SMase) stimulation and ceramide production. The SCF inhibitory effect on SM cycle was not influenced by wortmannin, a phosphoinositide-3 kinase (PI3K) inhibitor. The SCF protective effect was maintained in 32D-KitYF719 cells in which the PI3K/Akt signaling pathway is abolished due to mutation in Kit docking site for PI3K. In contrast, phospholipase C gamma (PLC gamma) inhibition by U73122 totally restored IR-induced N-SMase stimulation, ceramide production, and apoptosis in Kit-activated cells. Moreover, SCF did not protect 32D-KitYF728 cells (lacking a functional docking site for PLC gamma 1), from IR-induced SM cycle. Finally, SCF-induced radioprotection of human CD34(+) bone marrow cells was also inhibited by U73122. Altogether, these results suggest that SCF radioprotection is due to PLC gamma 1-dependent negative regulation of IR-induced N-SMase stimulation. Beyond the scope of Kit-expressing cells, it suggests that PLC gamma 1 status could greatly influence the post-DNA damage cellular response to IR, and perhaps, to other genotoxic agents.

  20. Deep Sequencing of the Medicago truncatula Root Transcriptome Reveals a Massive and Early Interaction between Nodulation Factor and Ethylene Signals.

    PubMed

    Larrainzar, Estíbaliz; Riely, Brendan K; Kim, Sang Cheol; Carrasquilla-Garcia, Noelia; Yu, Hee-Ju; Hwang, Hyun-Ju; Oh, Mijin; Kim, Goon Bo; Surendrarao, Anandkumar K; Chasman, Deborah; Siahpirani, Alireza F; Penmetsa, Ramachandra V; Lee, Gang-Seob; Kim, Namshin; Roy, Sushmita; Mun, Jeong-Hwan; Cook, Douglas R

    2015-09-01

    The legume-rhizobium symbiosis is initiated through the activation of the Nodulation (Nod) factor-signaling cascade, leading to a rapid reprogramming of host cell developmental pathways. In this work, we combine transcriptome sequencing with molecular genetics and network analysis to quantify and categorize the transcriptional changes occurring in roots of Medicago truncatula from minutes to days after inoculation with Sinorhizobium medicae. To identify the nature of the inductive and regulatory cues, we employed mutants with absent or decreased Nod factor sensitivities (i.e. Nodulation factor perception and Lysine motif domain-containing receptor-like kinase3, respectively) and an ethylene (ET)-insensitive, Nod factor-hypersensitive mutant (sickle). This unique data set encompasses nine time points, allowing observation of the symbiotic regulation of diverse biological processes with high temporal resolution. Among the many outputs of the study is the early Nod factor-induced, ET-regulated expression of ET signaling and biosynthesis genes. Coupled with the observation of massive transcriptional derepression in the ET-insensitive background, these results suggest that Nod factor signaling activates ET production to attenuate its own signal. Promoter:β-glucuronidase fusions report ET biosynthesis both in root hairs responding to rhizobium as well as in meristematic tissue during nodule organogenesis and growth, indicating that ET signaling functions at multiple developmental stages during symbiosis. In addition, we identified thousands of novel candidate genes undergoing Nod factor-dependent, ET-regulated expression. We leveraged the power of this large data set to model Nod factor- and ET-regulated signaling networks using MERLIN, a regulatory network inference algorithm. These analyses predict key nodes regulating the biological process impacted by Nod factor perception. We have made these results available to the research community through a searchable online

  1. Two signaling molecules share a phosphotyrosine-containing binding site in the platelet-derived growth factor receptor.

    PubMed

    Nishimura, R; Li, W; Kashishian, A; Mondino, A; Zhou, M; Cooper, J; Schlessinger, J

    1993-11-01

    Autophosphorylation sites of growth factor receptors with tyrosine kinase activity function as specific binding sites for Src homology 2 (SH2) domains of signaling molecules. This interaction appears to be a crucial step in a mechanism by which receptor tyrosine kinases relay signals to downstream signaling pathways. Nck is a widely expressed protein consisting exclusively of SH2 and SH3 domains, the overexpression of which causes cell transformation. It has been shown that various growth factors stimulate the phosphorylation of Nck and its association with autophosphorylated growth factor receptors. A panel of platelet-derived growth factor (PDGF) receptor mutations at tyrosine residues has been used to identify the Nck binding site. Here we show that mutation at Tyr-751 of the PDGF beta-receptor eliminates Nck binding both in vitro and in living cells. Moreover, the Y751F PDGF receptor mutant failed to mediate PDGF-stimulated phosphorylation of Nck in intact cells. A phosphorylated Tyr-751 is also required for binding of phosphatidylinositol-3 kinase to the PDGF receptor. Hence, the SH2 domains of p85 and Nck share a binding site in the PDGF receptor. Competition experiments with different phosphopeptides derived from the PDGF receptor suggest that binding of Nck and p85 is influenced by different residues around Tyr-751. Thus, a single tyrosine autophosphorylation site is able to link the PDGF receptor to two distinct SH2 domain-containing signaling molecules.

  2. The forkhead-like transcription factor (Fhl1p) maintains yeast replicative lifespan by regulating ribonucleotide reductase 1 (RNR1) gene transcription

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tai, Akiko; Kamei, Yuka; Mukai, Yukio

    In eukaryotes, numerous genetic factors contribute to the lifespan including metabolic enzymes, signal transducers, and transcription factors. As previously reported, the forkhead-like transcription factor (FHL1) gene was required for yeast replicative lifespan and cell proliferation. To determine how Fhl1p regulates the lifespan, we performed a DNA microarray analysis of a heterozygous diploid strain deleted for FHL1. We discovered numerous Fhl1p-target genes, which were then screened for lifespan-regulating activity. We identified the ribonucleotide reductase (RNR) 1 gene (RNR1) as a regulator of replicative lifespan. RNR1 encodes a large subunit of the RNR complex, which consists of two large (Rnr1p/Rnr3p) and twomore » small (Rnr2p/Rnr4p) subunits. Heterozygous deletion of FHL1 reduced transcription of RNR1 and RNR3, but not RNR2 and RNR4. Chromatin immunoprecipitation showed that Fhl1p binds to the promoter regions of RNR1 and RNR3. Cells harboring an RNR1 deletion or an rnr1-C428A mutation, which abolishes RNR catalytic activity, exhibited a short lifespan. In contrast, cells with a deletion of the other RNR genes had a normal lifespan. Overexpression of RNR1, but not RNR3, restored the lifespan of the heterozygous FHL1 mutant to the wild-type (WT) level. The Δfhl1/FHL1 mutant conferred a decrease in dNTP levels and an increase in hydroxyurea (HU) sensitivity. These findings reveal that Fhl1p regulates RNR1 gene transcription to maintain dNTP levels, thus modulating longevity by protection against replication stress. - Highlights: • Fhl1p regulates replicative lifespan and transcription of RNR large subunit genes. • Rnr1p uniquely acts as a lifespan regulator independent of the RNR complex. • dNTP levels modulate longevity by protection against replication stress.« less

  3. Lysophosphatidic acid stimulates epidermal growth factor-family ectodomain shedding and paracrine signaling from human lung fibroblasts.

    PubMed

    Shiomi, Tetsuya; Boudreault, Francis; Padem, Nurcicek; Higashiyama, Shigeki; Drazen, Jeffrey M; Tschumperlin, Daniel J

    2011-01-01

    Lysophospatidic acid (LPA) is a bioactive lipid mediator implicated in tissue repair and wound healing. It mediates diverse functional effects in fibroblasts, including proliferation, migration and contraction, but less is known about its ability to evoke paracrine signaling to other cell types involved in wound healing. We hypothesized that human pulmonary fibroblasts stimulated by LPA would exhibit ectodomain shedding of epidermal growth factor receptor (EGFR) ligands that signal to lung epithelial cells. To test this hypothesis, we used alkaline phosphatase-tagged EGFR ligand plasmids transfected into lung fibroblasts, and enzyme-linked immunosorbent assays to detect shedding of native ligands. LPA induced shedding of alkaline phosphatase-tagged heparin-binding epidermal growth factor (HB-EGF), amphiregulin, and transforming growth factor-a; non-transfected fibroblasts shed amphiregulin and HBEGF under baseline conditions, and increased shedding of HB-EGF in response to LPA. Treatment of fibroblasts with LPA resulted in elevated phosphorylation of extracellular signal-regulated kinase 1/2, enhanced expression of mRNA for c-fos, HB-EGF and amphiregulin, and enhanced proliferation at 96 hours. However, none of these fibroblast responses to LPA required ectodomain shedding or EGFR activity. To test the ability of LPA to stimulate paracrine signaling from fibroblasts, we transferred conditioned medium from LPA-stimulated cells, and found enhanced EGFR and extracellular signal-regulated kinase 1/2 phosphorylation in reporter A549 cells in excess of what could be accounted for by transferred LPA alone. These data show that LPA mediates EGF-family ectodomain shedding, resulting in enhanced paracrine signaling from lung fibroblasts to epithelial cells. © 2011 by the Wound Healing Society.

  4. Maintaining Fluoroquinolone Class Efficacy: Review of Influencing Factors

    PubMed Central

    2003-01-01

    Previous experience with antimicrobial resistance has emphasized the importance of appropriate stewardship of these pharmacotherapeutic agents. The introduction of fluoroquinolones provided potent new drugs directed primarily against gram-negative pathogens, while the newer members of this class demonstrate more activity against gram-positive species, including Streptococcus pneumoniae. Although these agents are clinically effective against a broad range of infectious agents, emergence of resistance and associated clinical failures have prompted reexamination of their use. Appropriate use revolves around two key objectives: 1) only prescribing antimicrobial therapy when it is beneficial and 2) using the agents(s) with optimal activity against the expected pathogens(s). Pharmacodynamic principles and properties can be applied to achieve the latter objective when prescribing agents belonging to the fluoroquinolone class. A focused approach emphasizing “correct-spectrum” coverage may reduce development of antimicrobial resistance and maintain class efficacy. PMID:12533274

  5. Movement Complexity and Neuromechanical Factors Affect the Entropic Half-Life of Myoelectric Signals

    PubMed Central

    Hodson-Tole, Emma F.; Wakeling, James M.

    2017-01-01

    Appropriate neuromuscular functioning is essential for survival and features underpinning motor control are present in myoelectric signals recorded from skeletal muscles. One approach to quantify control processes related to function is to assess signal variability using measures such as Sample Entropy. Here we developed a theoretical framework to simulate the effect of variability in burst duration, activation duty cycle, and intensity on the Entropic Half-Life (EnHL) in myoelectric signals. EnHLs were predicted to be <40 ms, and to vary with fluctuations in myoelectric signal amplitude and activation duty cycle. Comparison with myoelectic data from rats walking and running at a range of speeds and inclines confirmed the range of EnHLs, however, the direction of EnHL change in response to altered locomotor demand was not correctly predicted. The discrepancy reflected different associations between the ratio of the standard deviation and mean signal intensity (Ist:It¯) and duty factor in simulated and physiological data, likely reflecting additional information in the signals from the physiological data (e.g., quiescent phase content; variation in action potential shapes). EnHL could have significant value as a novel marker of neuromuscular responses to alterations in perceived locomotor task complexity and intensity. PMID:28974932

  6. Maintainability Program Requirements for Space Systems

    NASA Technical Reports Server (NTRS)

    1987-01-01

    This document is established to provide common general requirements for all NASA programs to: design maintainability into all systems where maintenance is a factor in system operation and mission success; and ensure that maintainability characteristics are developed through the systems engineering process. These requirements are not new. Design for ease of maintenance and minimization of repair time have always been fundamental requirements of the systems engineering process. However, new or reusable orbital manned and in-flight maintainable unmanned space systems demand special emphasis on maintainability, and this document has been prepared to meet that need. Maintainability requirements on many NASA programs differ in phasing and task emphasis from requirements promulgated by other Government agencies. This difference is due to the research and development nature of NASA programs where quantities produced are generally small; therefore, the depth of logistics support typical of many programs is generally not warranted. The cost of excessive maintenance is very high due to the logistics problems associated with the space environment. The ability to provide timely maintenance often involves safety considerations for manned space flight applications. This document represents a basic set of requirements that will achieve a design for maintenance. These requirements are directed primarily at manned and unmanned orbital space systems. To be effective, maintainability requirements should be tailored to meet specific NASA program and project needs and constraints. NASA activities shall invoke the requirements of this document consistent with program planning in procurements or on inhouse development efforts.

  7. MECHANISMS OF ZN-INDUCED SIGNAL INITIATION THROUGH THE EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR)

    EPA Science Inventory

    MECHANISMS OF Zn-INDUCED SIGNAL INITIATION THROUGH THE EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR)
    James M. Samet*, Lee M. Graves? and Weidong Wu?. *Human Studies Division, NHEERL, ORD, Research Triangle Park, NC 27711, and ?Center for Environmental Medicine, University of North C...

  8. Growth differentiation factor 9 signaling requires ERK1/2 activity in mouse granulosa and cumulus cells.

    PubMed

    Sasseville, Maxime; Ritter, Lesley J; Nguyen, Thao M; Liu, Fang; Mottershead, David G; Russell, Darryl L; Gilchrist, Robert B

    2010-09-15

    Ovarian folliculogenesis is driven by the combined action of endocrine cues and paracrine factors. The oocyte secretes powerful mitogens, such as growth differentiation factor 9 (GDF9), that regulate granulosa cell proliferation, metabolism, steroidogenesis and differentiation. This study investigated the role of the epidermal growth factor receptor (EGFR)-extracellular signal-regulated kinase 1 and 2 (ERK1/2; also known as MAPK3/1) signaling pathway on GDF9 action on granulosa cells. Results show that mitogenic action of the oocyte is prevented by pharmacological inhibition of the EGFR-ERK1/2 pathway. Importantly, EGFR-ERK1/2 activity as well as rous sarcoma oncogene family kinases (SFK) are required for signaling through SMADs, mediating GDF9, activin A and TGFbeta1 mitogenic action in granulosa cells. GDF9 could not activate ERK1/2 or affect EGF-stimulated ERK1/2 in granulosa cells. However, induction of the SMAD3-specific CAGA reporter by GDF9 in granulosa cells required active EGFR, SFKs and ERK1/2 as did GDF9-responsive gene expression. Finally, the EGFR-SFKs-ERK1/2 pathway was shown to be required for the maintenance of phosphorylation of the SMAD3 linker region. Together our results suggest that receptivity of granulosa cells to oocyte-secreted factors, including GDF9, is regulated by the level of activation of the EGFR and resulting ERK1/2 activity, through the requisite permissive phosphorylation of SMAD3 in the linker region. Our results indicate that oocyte-secreted TGFbeta-like ligands and EGFR-ERK1/2 signaling are cooperatively required for the unique granulosa cell response to the signal from oocytes mediating granulosa cell survival and proliferation and hence the promotion of follicle growth and ovulation.

  9. Wnt6 maintains anterior escort cells as an integral component of the germline stem cell niche

    PubMed Central

    2018-01-01

    ABSTRACT Stem cells reside in a niche, a local environment whose cellular and molecular complexity is still being elucidated. In Drosophila ovaries, germline stem cells depend on cap cells for self-renewing signals and physical attachment. Germline stem cells also contact the anterior escort cells, and here we report that anterior escort cells are absolutely required for germline stem cell maintenance. When escort cells die from impaired Wnt signaling or hid expression, the loss of anterior escort cells causes loss of germline stem cells. Anterior escort cells function as an integral niche component by promoting DE-cadherin anchorage and by transiently expressing the Dpp ligand to promote full-strength BMP signaling in germline stem cells. Anterior escort cells are maintained by Wnt6 ligands produced by cap cells; without Wnt6 signaling, anterior escort cells die leaving vacancies in the niche, leading to loss of germline stem cells. Our data identify anterior escort cells as constituents of the germline stem cell niche, maintained by a cap cell-produced Wnt6 survival signal. PMID:29361569

  10. Wnt6 maintains anterior escort cells as an integral component of the germline stem cell niche.

    PubMed

    Wang, Xiaoxi; Page-McCaw, Andrea

    2018-02-07

    Stem cells reside in a niche, a local environment whose cellular and molecular complexity is still being elucidated. In Drosophila ovaries, germline stem cells depend on cap cells for self-renewing signals and physical attachment. Germline stem cells also contact the anterior escort cells, and here we report that anterior escort cells are absolutely required for germline stem cell maintenance. When escort cells die from impaired Wnt signaling or hid expression, the loss of anterior escort cells causes loss of germline stem cells. Anterior escort cells function as an integral niche component by promoting DE-cadherin anchorage and by transiently expressing the Dpp ligand to promote full-strength BMP signaling in germline stem cells. Anterior escort cells are maintained by Wnt6 ligands produced by cap cells; without Wnt6 signaling, anterior escort cells die leaving vacancies in the niche, leading to loss of germline stem cells. Our data identify anterior escort cells as constituents of the germline stem cell niche, maintained by a cap cell-produced Wnt6 survival signal. © 2018. Published by The Company of Biologists Ltd.

  11. Intercellular signaling through secreted proteins induces free-energy gradient-directed cell movement.

    PubMed

    Kravchenko-Balasha, Nataly; Shin, Young Shik; Sutherland, Alex; Levine, R D; Heath, James R

    2016-05-17

    Controlling cell migration is important in tissue engineering and medicine. Cell motility depends on factors such as nutrient concentration gradients and soluble factor signaling. In particular, cell-cell signaling can depend on cell-cell separation distance and can influence cellular arrangements in bulk cultures. Here, we seek a physical-based approach, which identifies a potential governed by cell-cell signaling that induces a directed cell-cell motion. A single-cell barcode chip (SCBC) was used to experimentally interrogate secreted proteins in hundreds of isolated glioblastoma brain cancer cell pairs and to monitor their relative motions over time. We used these trajectories to identify a range of cell-cell separation distances where the signaling was most stable. We then used a thermodynamics-motivated analysis of secreted protein levels to characterize free-energy changes for different cell-cell distances. We show that glioblastoma cell-cell movement can be described as Brownian motion biased by cell-cell potential. To demonstrate that the free-energy potential as determined by the signaling is the driver of motion, we inhibited two proteins most involved in maintaining the free-energy gradient. Following inhibition, cell pairs showed an essentially random Brownian motion, similar to the case for untreated, isolated single cells.

  12. Lon in maintaining mitochondrial and endoplasmic reticulum homeostasis.

    PubMed

    Yang, Jieyeqi; Chen, Wenying; Zhang, Boyang; Tian, Fengli; Zhou, Zheng; Liao, Xin; Li, Chen; Zhang, Yi; Han, Yanyan; Wang, Yan; Li, Yuzhe; Wang, Guo-Qing; Shen, Xiao Li

    2018-06-01

    As a vital member of AAA+ (ATPase associated with diverse cellular activities) protein superfamily, Lon, a homo-hexameric ring-shaped protein complex with a serine-lysine catalytic dyad, is highly conserved throughout almost all prokaryotic and eukaryotic organisms. Lon protease (LONP) plays an important role in maintaining mitoproteostasis through selectively recognizing and degrading oxidatively modified mitoproteins within mitochondrial matrix, such as oxidized aconitase, phosphorylated mitochondrial transcription factor A, etc. Furthermore, the up-regulated LONP increased mitochondrial ROS generation to promote cell survival, cell proliferation, epithelial-mesenchymal transition, and cell migration, which was attributed to the up-regulation of NADH:ubiquinone oxidoreductase core subunit S8 via interaction with chaperone Lon under hypoxic or oxidative stress in tumorigenesis. In addition, Lon also participated in protein kinase RNA (PKR)-like endoplasmic reticulum kinase signaling pathway under endoplasmic reticulum (ER) stress. In short, Lon, as a pivotal stress-responsive protein that involved in the crosstalks among mitochondria, ER and nucleus, participated in multifarious important cellular processes crucial for cell survival, such as the mitochondrial protein quality control system, the mitochondrial unfolded protein response, the mtDNA maintenance, and the ER unfolded protein response.

  13. Hypoxia-inducible factor-1 signalling promotes goblet cell hyperplasia in airway epithelium

    PubMed Central

    Polosukhin, Vasiliy V; Cates, Justin M; Lawson, William E; Milstone, Aaron P; Matafonov, Anton G; Massion, Pierre P; Lee, Jae Woo; Randell, Scott H; Blackwell, Timothy S

    2018-01-01

    Goblet cell hyperplasia is a common feature of chronic obstructive pulmonary disease (COPD) airways, but the mechanisms that underlie this epithelial remodelling in COPD are not understood. Based on our previous finding of hypoxia-inducible factor-1α (HIF-1α) nuclear localization in large airways from patients with COPD, we investigated whether hypoxia-inducible signalling could influence the development of goblet cell hyperplasia. We evaluated large airway samples obtained from 18 lifelong non-smokers and 13 former smokers without COPD, and 45 former smokers with COPD. In these specimens, HIF-1α nuclear staining occurred almost exclusively in COPD patients in areas of airway remodelling. In COPD patients, 93.2 ± 3.9% (range 65 – 100%) of goblet cells were HIF-1α positive in areas of goblet cell hyperplasia, whereas nuclear HIF-1α was not detected in individuals without COPD or in normal-appearing pseudostratified epithelium from COPD patients. To determine the direct effects of hypoxia-inducible signalling on epithelial cell differentiation in vitro, human bronchial epithelial cells (HBECs) were grown in air-liquid interface cultures under hypoxia (1% O2) or following treatment with a selective HIF-1α stabilizer, (2R)-[(4-biphenylylsulphonyl)amino]-N-hydroxy-3-phenyl-propionamide (BiPS). HBECs grown in hypoxia or with BiPS treatment were characterized by HIF-1α activation, carbonic anhydrase IX expression, mucus-producing cell hyperplasia and increased expression of MUC5AC. Analysis of signal transduction pathways in cells with HIF-1α activation showed increased ERK1/2 phosphorylation without activation of epidermal growth factor receptor, Ras, PI3K-Akt or STAT6. These data indicate an important effect of hypoxia-inducible signalling on airway epithelial cell differentiation and identify a new potential target to limit mucus production in COPD. PMID:21557221

  14. The role of cross-sectional geometry, curvature, and limb posture in maintaining equal safety factors: a computed tomography study.

    PubMed

    Brassey, Charlotte A; Kitchener, Andrew C; Withers, Philip J; Manning, Phillip L; Sellers, William I

    2013-03-01

    The limb bones of an elephant are considered to experience similar peak locomotory stresses as a shrew. "Safety factors" are maintained across the entire range of body masses through a combination of robusticity of long bones, postural variation, and modification of gait. The relative contributions of these variables remain uncertain. To test the role of shape change, we undertook X-ray tomographic scans of the leg bones of 60 species of mammals and birds, and extracted geometric properties. The maximum resistible forces the bones could withstand before yield under compressive, bending, and torsional loads were calculated using standard engineering equations incorporating curvature. Positive allometric scaling of cross-sectional properties with body mass was insufficient to prevent negative allometry of bending (F(b) ) and torsional maximum force (F(t) ) (and hence decreasing safety factors) in mammalian (femur F(b) ∞M(b) (0.76) , F(t) ∞M(b) (0.80) ; tibia F(b) ∞M(b) (0.80) , F(t) ∞M(b) (0.76) ) and avian hindlimbs (tibiotarsus F(b) ∞M(b) (0.88) , F(t) ∞M(b) (0.89) ) with the exception of avian femoral F(b) and F(t) . The minimum angle from horizontal a bone must be held while maintaining a given safety factor under combined compressive and bending loads increases with M(b) , with the exception of the avian femur. Postural erectness is shown as an effective means of achieving stress similarity in mammals. The scaling behavior of the avian femur is discussed in light of unusual posture and kinematics. Copyright © 2013 Wiley Periodicals, Inc.

  15. The CD8+ memory T-cell state of readiness is actively maintained and reversible

    PubMed Central

    Allam, Atef; Conze, Dietrich B.; Giardino Torchia, Maria Letizia; Munitic, Ivana; Yagita, Hideo; Sowell, Ryan T.; Marzo, Amanda L.

    2009-01-01

    The ability of the adaptive immune system to respond rapidly and robustly upon repeated antigen exposure is known as immunologic memory, and it is thought that acquisition of memory T-cell function is an irreversible differentiation event. In this study, we report that many phenotypic and functional characteristics of antigen-specific CD8 memory T cells are lost when they are deprived of contact with dendritic cells. Under these circumstances, memory T cells reverted from G1 to the G0 cell-cycle state and responded to stimulation like naive T cells, as assessed by proliferation, dependence upon costimulation, and interferon-γ production, without losing cell surface markers associated with memory. The memory state was maintained by signaling via members of the tumor necrosis factor receptor superfamily, CD27 and 4-1BB. Foxo1, a transcription factor involved in T-cell quiescence, was reduced in memory cells, and stimulation of naive CD8 cells via CD27 caused Foxo1 to be phosphorylated and emigrate from the nucleus in a phosphatidylinositol-3 kinase–dependent manner. Consistent with these results, maintenance of G1 in vivo was compromised in antigen-specific memory T cells in vesicular stomatitis virus-infected CD27-deficient mice. Therefore, sustaining the functional phenotype of T memory cells requires active signaling and maintenance. PMID:19617575

  16. Regulator of G protein signaling 4 is a novel target of GATA-6 transcription factor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Yonggang; Li, Fang; Xiao, Xiao

    GATA transcription factors regulate an array of genes important in cell proliferation and differentiation. Here we report the identification of regulator of G protein signaling 4 (RGS4) as a novel target for GATA-6 transcription factor. Although three sites (a, b, c) within the proximal region of rabbit RGS4 promoter for GATA transcription factors were predicted by bioinformatics analysis, only GATA-a site (16 bp from the core TATA box) is essential for RGS4 transcriptional regulation. RT-PCR analysis demonstrated that only GATA-6 was highly expressed in rabbit colonic smooth muscle cells but GATA-4/6 were expressed in cardiac myocytes and GATA-1/2/3 expressed inmore » blood cells. Adenovirus-mediated expression of GATA-6 but not GATA-1 significantly increased the constitutive and IL-1β-induced mRNA expression of the endogenous RGS4 in colonic smooth muscle cells. IL-1β stimulation induced GATA-6 nuclear translocation and increased GATA-6 binding to RGS4 promoter. These data suggest that GATA factor could affect G protein signaling through regulating RGS4 expression, and GATA signaling may develop as a future therapeutic target for RGS4-related diseases. - Highlights: • GATA-6 is highly expressed in colonic smooth muscle cells. • RGS4 is a novel target for GATA-6 transcription factor. • GATA-a response element is essential to regulate the core promoter of RGS4. • GATA-6 regulates IL-1β-induced RGS4 upregulation.« less

  17. PHF20 regulates NF-κB signalling by disrupting recruitment of PP2A to p65

    PubMed Central

    Zhang, Tiejun; Park, Kyeong Ah; Li, Yuwen; Byun, Hee Sun; Jeon, Juhee; Lee, Yoonjung; Hong, Jang Hee; Kim, Jin Man; Huang, Song-Mei; Choi, Seung-Won; Kim, Sun-Hwan; Sohn, Kyung-Cheol; Ro, Hyunju; Lee, Ji Hoon; Lu, Tao; Stark, George R.; Shen, Han-Ming; Liu, Zheng-gang; Park, Jongsun; Hur, Gang Min

    2014-01-01

    Constitutive NF-κB activation in cancer cells is caused by defects in the signalling network responsible for terminating the NF-κB response. Here we report that plant homeodomain finger protein 20 maintains NF-κB in an active state in the nucleus by inhibiting the interaction between PP2A and p65. We show that plant homeodomain finger protein 20 induces canonical NF-κB signalling by increasing the DNA-binding activity of NF-κB subunit p65. In plant homeodomain finger protein 20-overexpressing cells, the termination of tumour necrosis factor-induced p65 phosphorylation is impaired whereas upstream signalling events triggered by tumour necrosis factor are unaffected. This effect strictly depends on the interaction between plant homeodomain finger protein 20 and methylated lysine residues of p65, which hinders recruitment of PP2A to p65, thereby maintaining p65 in a phosphorylated state. We further show that plant homeodomain finger protein 20 levels correlate with p65 phosphorylation levels in human glioma specimens. Our work identifies plant homeodomain finger protein 20 as a novel regulator of NF-κB activation and suggests that elevated expression of plant homeodomain finger protein 20 may drive constitutive NF-κB activation in some cancers. PMID:23797602

  18. AP1 transcription factors are required to maintain the peripheral taste system.

    PubMed

    Shandilya, Jayasha; Gao, Yankun; Nayak, Tapan K; Roberts, Stefan G E; Medler, Kathryn F

    2016-10-27

    The sense of taste is used by organisms to achieve the optimal nutritional requirement and avoid potentially toxic compounds. In the oral cavity, taste receptor cells are grouped together in taste buds that are present in specialized taste papillae in the tongue. Taste receptor cells are the cells that detect chemicals in potential food items and transmit that information to gustatory nerves that convey the taste information to the brain. As taste cells are in contact with the external environment, they can be damaged and are routinely replaced throughout an organism's lifetime to maintain functionality. However, this taste cell turnover loses efficiency over time resulting in a reduction in taste ability. Currently, very little is known about the mechanisms that regulate the renewal and maintenance of taste cells. We therefore performed RNA-sequencing analysis on isolated taste cells from 2 and 6-month-old mice to determine how alterations in the taste cell-transcriptome regulate taste cell maintenance and function in adults. We found that the activator protein-1 (AP1) transcription factors (c-Fos, Fosb and c-Jun) and genes associated with this pathway were significantly downregulated in taste cells by 6 months and further declined at 12 months. We generated conditional c-Fos-knockout mice to target K14-expressing cells, including differentiating taste cells. c-Fos deletion caused a severe perturbation in taste bud structure and resulted in a significant reduction in the taste bud size. c-Fos deletion also affected taste cell turnover as evident by a decrease in proliferative marker, and upregulation of the apoptotic marker cleaved-PARP. Thus, AP1 factors are important regulators of adult taste cell renewal and their downregulation negatively impacts taste maintenance.

  19. AP1 transcription factors are required to maintain the peripheral taste system

    PubMed Central

    Shandilya, Jayasha; Gao, Yankun; Nayak, Tapan K; Roberts, Stefan G E; Medler, Kathryn F

    2016-01-01

    The sense of taste is used by organisms to achieve the optimal nutritional requirement and avoid potentially toxic compounds. In the oral cavity, taste receptor cells are grouped together in taste buds that are present in specialized taste papillae in the tongue. Taste receptor cells are the cells that detect chemicals in potential food items and transmit that information to gustatory nerves that convey the taste information to the brain. As taste cells are in contact with the external environment, they can be damaged and are routinely replaced throughout an organism's lifetime to maintain functionality. However, this taste cell turnover loses efficiency over time resulting in a reduction in taste ability. Currently, very little is known about the mechanisms that regulate the renewal and maintenance of taste cells. We therefore performed RNA-sequencing analysis on isolated taste cells from 2 and 6-month-old mice to determine how alterations in the taste cell-transcriptome regulate taste cell maintenance and function in adults. We found that the activator protein-1 (AP1) transcription factors (c-Fos, Fosb and c-Jun) and genes associated with this pathway were significantly downregulated in taste cells by 6 months and further declined at 12 months. We generated conditional c-Fos-knockout mice to target K14-expressing cells, including differentiating taste cells. c-Fos deletion caused a severe perturbation in taste bud structure and resulted in a significant reduction in the taste bud size. c-Fos deletion also affected taste cell turnover as evident by a decrease in proliferative marker, and upregulation of the apoptotic marker cleaved-PARP. Thus, AP1 factors are important regulators of adult taste cell renewal and their downregulation negatively impacts taste maintenance. PMID:27787515

  20. Insulin-like growth factor-1 signaling in renal cell carcinoma.

    PubMed

    Tracz, Adam F; Szczylik, Cezary; Porta, Camillo; Czarnecka, Anna M

    2016-07-12

    Renal cell carcinoma (RCC) incidence is highest in highly developed countries and it is the seventh most common neoplasm diagnosed. RCC management include nephrectomy and targeted therapies. Type 1 insulin-like growth factor (IGF-1) pathway plays an important role in cell proliferation and apoptosis resistance. IGF-1 and insulin share overlapping downstream signaling pathways in normal and cancer cells. IGF-1 receptor (IGF1R) stimulation may promote malignant transformation promoting cell proliferation, dedifferentiation and inhibiting apoptosis. Clear cell renal cell carcinoma (ccRCC) patients with IGF1R overexpression have 70 % increased risk of death compared to patients who had tumors without IGF1R expression. IGF1R signaling deregulation may results in p53, WT, BRCA1, VHL loss of function. RCC cells with high expression of IGF1R are more resistant to chemotherapy than cells with low expression. Silencing of IGF1R increase the chemosensitivity of ccRCC cells and the effect is greater in VHL mutated cells. Understanding the role of IGF-1 signaling pathway in RCC may result in development of new targeted therapeutic interventions. First preclinical attempts with anti-IGF-1R monoclonal antibodies or fragment antigen-binding (Fab) fragments alone or in combination with an mTOR inhibitor were shown to inhibit in vitro growth and reduced the number of colonies formed by of RCC cells.

  1. Regulation of Prostate Development and Benign Prostatic Hyperplasia by Autocrine Cholinergic Signaling via Maintaining the Epithelial Progenitor Cells in Proliferating Status.

    PubMed

    Wang, Naitao; Dong, Bai-Jun; Quan, Yizhou; Chen, Qianqian; Chu, Mingliang; Xu, Jin; Xue, Wei; Huang, Yi-Ran; Yang, Ru; Gao, Wei-Qiang

    2016-05-10

    Regulation of prostate epithelial progenitor cells is important in prostate development and prostate diseases. Our previous study demonstrated a function of autocrine cholinergic signaling (ACS) in promoting prostate cancer growth and castration resistance. However, whether or not such ACS also plays a role in prostate development is unknown. Here, we report that ACS promoted the proliferation and inhibited the differentiation of prostate epithelial progenitor cells in organotypic cultures. These results were confirmed by ex vivo lineage tracing assays and in vivo renal capsule recombination assays. Moreover, we found that M3 cholinergic receptor (CHRM3) was upregulated in a large subset of benign prostatic hyperplasia (BPH) tissues compared with normal tissues. Activation of CHRM3 also promoted the proliferation of BPH cells. Together, our findings identify a role of ACS in maintaining prostate epithelial progenitor cells in the proliferating state, and blockade of ACS may have clinical implications for the management of BPH. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  2. FLCN Maintains the Leucine Level in Lysosome to Stimulate mTORC1

    PubMed Central

    Chen, Zhi; Ji, Xin; Qiao, Xianfeng; Jin, Yaping; Liu, Wei

    2016-01-01

    The intracellular amino acid pool within lysosome is a signal that stimulates the nutrient-sensing mTORC1 signalling pathway. The signal transduction cascade has garnered much attention, but little is known about the sequestration of the signalling molecules within the lysosome. Using human HEK293 cells as a model, we found that suppression of the BHD syndrome gene FLCN reduced the leucine level in lysosome, which correlated with decreased mTORC1 activity. Both consequences could be reversed by supplementation with high levels of leucine, but not other tested amino acids. Conversely, overexpressed FLCN could sequester lysosomal leucine and stimulate mTORC1 in an amino acid limitation environment. These results identify a novel function of FLCN: it controls mTORC1 by modulating the leucine signal in lysosome. Furthermore, we provided evidence that FLCN exerted this role by inhibiting the accumulation of the amino acid transporter PAT1 on the lysosome surface, thereby maintaining the signal level within the organelle. PMID:27280402

  3. Nerve Growth Factor Regulates Transient Receptor Potential Vanilloid 2 via Extracellular Signal-Regulated Kinase Signaling To Enhance Neurite Outgrowth in Developing Neurons

    PubMed Central

    Cohen, Matthew R.; Johnson, William M.; Pilat, Jennifer M.; Kiselar, Janna; DeFrancesco-Lisowitz, Alicia; Zigmond, Richard E.

    2015-01-01

    Neurite outgrowth is key to the formation of functional circuits during neuronal development. Neurotrophins, including nerve growth factor (NGF), increase neurite outgrowth in part by altering the function and expression of Ca2+-permeable cation channels. Here we report that transient receptor potential vanilloid 2 (TRPV2) is an intracellular Ca2+-permeable TRPV channel upregulated by NGF via the mitogen-activated protein kinase (MAPK) signaling pathway to augment neurite outgrowth. TRPV2 colocalized with Rab7, a late endosome protein, in addition to TrkA and activated extracellular signal-regulated kinase (ERK) in neurites, indicating that the channel is closely associated with signaling endosomes. In line with these results, we showed that TRPV2 acts as an ERK substrate and identified the motifs necessary for phosphorylation of TRPV2 by ERK. Furthermore, neurite length, TRPV2 expression, and TRPV2-mediated Ca2+ signals were reduced by mutagenesis of these key ERK phosphorylation sites. Based on these findings, we identified a previously uncharacterized mechanism by which ERK controls TRPV2-mediated Ca2+ signals in developing neurons and further establish TRPV2 as a critical intracellular ion channel in neuronal function. PMID:26416880

  4. Local Epidermal Growth Factor Receptor Signaling Mediates the Systemic Pathogenic Effects of Staphylococcus aureus Toxic Shock Syndrome.

    PubMed

    Breshears, Laura M; Gillman, Aaron N; Stach, Christopher S; Schlievert, Patrick M; Peterson, Marnie L

    2016-01-01

    Secreted factors of Staphylococcus aureus can activate host signaling from the epidermal growth factor receptor (EGFR). The superantigen toxic shock syndrome toxin-1 (TSST-1) contributes to mucosal cytokine production through a disintegrin and metalloproteinase (ADAM)-mediated shedding of EGFR ligands and subsequent EGFR activation. The secreted hemolysin, α-toxin, can also induce EGFR signaling and directly interacts with ADAM10, a sheddase of EGFR ligands. The current work explores the role of EGFR signaling in menstrual toxic shock syndrome (mTSS), a disease mediated by TSST-1. The data presented show that TSST-1 and α-toxin induce ADAM- and EGFR-dependent cytokine production from human vaginal epithelial cells. TSST-1 and α-toxin also induce cytokine production from an ex vivo porcine vaginal mucosa (PVM) model. EGFR signaling is responsible for the majority of IL-8 production from PVM in response to secreted toxins and live S. aureus. Finally, data are presented demonstrating that inhibition of EGFR signaling with the EGFR-specific tyrosine kinase inhibitor AG1478 significantly increases survival in a rabbit model of mTSS. These data indicate that EGFR signaling is critical for progression of an S. aureus exotoxin-mediated disease and may represent an attractive host target for therapeutics.

  5. Corticotropin-releasing factor overexpression gives rise to sex differences in Alzheimer's disease-related signaling.

    PubMed

    Bangasser, D A; Dong, H; Carroll, J; Plona, Z; Ding, H; Rodriguez, L; McKennan, C; Csernansky, J G; Seeholzer, S H; Valentino, R J

    2017-08-01

    Several neuropsychiatric and neurodegenerative disorders share stress as a risk factor and are more prevalent in women than in men. Corticotropin-releasing factor (CRF) orchestrates the stress response, and excessive CRF is thought to contribute to the pathophysiology of these diseases. We previously found that the CRF 1 receptor (CRF 1 ) is sex biased whereby coupling to its GTP-binding protein, Gs, is greater in females, whereas β-arrestin-2 coupling is greater in males. This study used a phosphoproteomic approach in CRF-overexpressing (CRF-OE) mice to test the proof of principle that when CRF is in excess, sex-biased CRF 1 coupling translates into divergent cell signaling that is expressed as different brain phosphoprotein profiles. Cortical phosphopeptides that distinguished female and male CRF-OE mice were overrepresented in unique pathways that were consistent with Gs-dependent signaling in females and β-arrestin-2 signaling in males. Notably, phosphopeptides that were more abundant in female CRF-OE mice were overrepresented in an Alzheimer's disease (AD) pathway. Phosphoproteomic results were validated by demonstrating that CRF overexpression in females was associated with increased tau phosphorylation and, in a mouse model of AD pathology, phosphorylation of β-secretase, the enzyme involved in the formation of amyloid β. These females exhibited increased formation of amyloid β plaques and cognitive impairments relative to males. Collectively, the findings are consistent with a mechanism whereby the excess CRF that characterizes stress-related diseases initiates distinct cellular processes in male and female brains, as a result of sex-biased CRF 1 signaling. Promotion of AD-related signaling pathways through this mechanism may contribute to female vulnerability to AD.

  6. A role for Runx transcription factor signaling in dorsal root ganglion sensory neuron diversification.

    PubMed

    Kramer, Ina; Sigrist, Markus; de Nooij, Joriene C; Taniuchi, Ichiro; Jessell, Thomas M; Arber, Silvia

    2006-02-02

    Subpopulations of sensory neurons in the dorsal root ganglion (DRG) can be characterized on the basis of sensory modalities that convey distinct peripheral stimuli, but the molecular mechanisms that underlie sensory neuronal diversification remain unclear. Here, we have used genetic manipulations in the mouse embryo to examine how Runx transcription factor signaling controls the acquisition of distinct DRG neuronal subtype identities. Runx3 acts to diversify an Ngn1-independent neuronal cohort by promoting the differentiation of proprioceptive sensory neurons through erosion of TrkB expression in prospective TrkC+ sensory neurons. In contrast, Runx1 controls neuronal diversification within Ngn1-dependent TrkA+ neurons by repression of neuropeptide CGRP expression and controlling the fine pattern of laminar termination in the dorsal spinal cord. Together, our findings suggest that Runx transcription factor signaling plays a key role in sensory neuron diversification.

  7. Osteocyte-Intrinsic TGF-β Signaling Regulates Bone Quality through Perilacunar/Canalicular Remodeling

    DOE PAGES

    Dole, Neha S.; Mazur, Courtney M.; Acevedo, Claire; ...

    2017-11-28

    Poor bone quality contributes to bone fragility in diabetes, aging, and osteogenesis imperfecta. However, the mechanisms controlling bone quality are not well understood, contributing to the current lack of strategies to diagnose or treat bone quality deficits. Transforming growth factor beta (TGF-β) signaling is a crucial mechanism known to regulate the material quality of bone, but its cellular target in this regulation is unknown. Studies showing that osteocytes directly remodel their perilacunar/canalicular matrix led us to hypothesize that TGF-β controls bone quality through perilacunar/canalicular remodeling (PLR). Using inhibitors and mice with an osteocyte-intrinsic defect in TGF-β signaling (TβRII ocy-/-), wemore » show that TGF-β regulates PLR in a cell-intrinsic manner to control bone quality. Altogether, this study emphasizes that osteocytes are key in executing the biological control of bone quality through PLR, thereby highlighting the fundamental role of osteocyte-mediated PLR in bone homeostasis and fragility. Resistance to fracture requires healthy bone mass and quality. However, the cellular mechanisms regulating bone quality are unclear. Dole et al. show that osteocyte-intrinsic TGF-β signaling maintains bone quality through perilacunar/canalicular remodeling. Thus, osteocytes mediate perilacunar/canalicular remodeling and osteoclast-directed remodeling to cooperatively maintain bone quality and mass and prevent fragility.« less

  8. Osteocyte-Intrinsic TGF-β Signaling Regulates Bone Quality through Perilacunar/Canalicular Remodeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dole, Neha S.; Mazur, Courtney M.; Acevedo, Claire

    Poor bone quality contributes to bone fragility in diabetes, aging, and osteogenesis imperfecta. However, the mechanisms controlling bone quality are not well understood, contributing to the current lack of strategies to diagnose or treat bone quality deficits. Transforming growth factor beta (TGF-β) signaling is a crucial mechanism known to regulate the material quality of bone, but its cellular target in this regulation is unknown. Studies showing that osteocytes directly remodel their perilacunar/canalicular matrix led us to hypothesize that TGF-β controls bone quality through perilacunar/canalicular remodeling (PLR). Using inhibitors and mice with an osteocyte-intrinsic defect in TGF-β signaling (TβRII ocy-/-), wemore » show that TGF-β regulates PLR in a cell-intrinsic manner to control bone quality. Altogether, this study emphasizes that osteocytes are key in executing the biological control of bone quality through PLR, thereby highlighting the fundamental role of osteocyte-mediated PLR in bone homeostasis and fragility. Resistance to fracture requires healthy bone mass and quality. However, the cellular mechanisms regulating bone quality are unclear. Dole et al. show that osteocyte-intrinsic TGF-β signaling maintains bone quality through perilacunar/canalicular remodeling. Thus, osteocytes mediate perilacunar/canalicular remodeling and osteoclast-directed remodeling to cooperatively maintain bone quality and mass and prevent fragility.« less

  9. Operating guidelines for TxDOT ramp control signals.

    DOT National Transportation Integrated Search

    2009-01-01

    The Texas Department of Transportation (TxDOT) currently maintains a Traffic Signals Manual. : Originally published in 1999, this manual provides a guide and reference for handling requests : for traffic signals on the designated State Highway System...

  10. The Caenorhabditis elegans EGL-15 Signaling Pathway Implicates a DOS-Like Multisubstrate Adaptor Protein in Fibroblast Growth Factor Signal Transduction

    PubMed Central

    Schutzman, Jennifer L.; Borland, Christina Z.; Newman, John C.; Robinson, Matthew K.; Kokel, Michelle; Stern, Michael J.

    2001-01-01

    EGL-15 is a fibroblast growth factor receptor in the nematode Caenorhabditis elegans. Components that mediate EGL-15 signaling have been identified via mutations that confer a Clear (Clr) phenotype, indicative of hyperactivity of this pathway, or a suppressor-of-Clr (Soc) phenotype, indicative of reduced pathway activity. We have isolated a gain-of-function allele of let-60 ras that confers a Clr phenotype and implicated both let-60 ras and components of a mitogen-activated protein kinase cascade in EGL-15 signaling by their Soc phenotype. Epistasis analysis indicates that the gene soc-1 functions in EGL-15 signaling by acting either upstream of or independently of LET-60 RAS. soc-1 encodes a multisubstrate adaptor protein with an amino-terminal pleckstrin homology domain that is structurally similar to the DOS protein in Drosophila and mammalian GAB1. DOS is known to act with the cytoplasmic tyrosine phosphatase Corkscrew (CSW) in signaling pathways in Drosophila. Similarly, the C. elegans CSW ortholog PTP-2 was found to be involved in EGL-15 signaling. Structure-function analysis of SOC-1 and phenotypic analysis of single and double mutants are consistent with a model in which SOC-1 and PTP-2 act together in a pathway downstream of EGL-15 and the Src homology domain 2 (SH2)/SH3-adaptor protein SEM-5/GRB2 contributes to SOC-1-independent activities of EGL-15. PMID:11689700

  11. The sonic hedgehog signaling pathway maintains the cancer stem cell self-renewal of anaplastic thyroid cancer by inducing snail expression.

    PubMed

    Heiden, Katherine B; Williamson, Ashley J; Doscas, Michelle E; Ye, Jin; Wang, Yimin; Liu, Dingxie; Xing, Mingzhao; Prinz, Richard A; Xu, Xiulong

    2014-11-01

    Cancer stem cells (CSCs) have been recently identified in thyroid neoplasm. Anaplastic thyroid cancer (ATC) contains a higher percentage of CSCs than well-differentiated thyroid cancer. The signaling pathways and the transcription factors that regulate thyroid CSC self-renewal remain poorly understood. The objective of this study is to use two ATC cell lines (KAT-18 and SW1736) as a model to study the role of the sonic hedgehog (Shh) pathway in maintaining thyroid CSC self-renewal and to understand its underlying molecular mechanisms. The expression and activity of aldehyde dehydrogenase (ALDH), a marker for thyroid CSCs, was analyzed by Western blot and ALDEFLUOR assay, respectively. The effect of three Shh pathway inhibitors (cyclopamine, HhAntag, GANT61), Shh, Gli1, Snail knockdown, and Gli1 overexpression on thyroid CSC self-renewal was analyzed by ALDEFLUOR assay and thyrosphere formation. The sensitivity of transfected KAT-18 cells to radiation was evaluated by a colony survival assay. Western blot analysis revealed that ALDH protein levels in five thyroid cancer cell lines (WRO82, a follicular thyroid cancer cell line; BCPAP and TPC1, two papillary thyroid cancer cell lines; KAT-18 and SW1736, two ATC cell lines) correlated with the percentage of the ALDH(High) cells as well as Gli1 and Snail expression. The Shh pathway inhibitors, Shh and Gli1 knockdown, in KAT-18 cells decreased thyroid CSC self-renewal and increased radiation sensitivity. In contrast, Gli1 overexpression led to increased thyrosphere formation, an increased percentage of ALDH(High) cells, and increased radiation resistance in KAT-18 cells. Inhibition of the Shh pathway by three specific inhibitors led to decreased Snail expression and a decreased number of ALDH(High) cells in KAT-18 and SW1736. Snail gene knockdown decreased the number of ALDH(High) cells in KAT-18 and SW1736 cells. The Shh pathway promotes the CSC self-renewal in ATC cell lines by Gli1-induced Snail expression.

  12. The Phosphatidylinositol 3-Kinase/Akt Pathway Regulates Transforming Growth FactorSignaling by Destabilizing Ski and Inducing Smad7*

    PubMed Central

    Band, Arja M.; Björklund, Mia; Laiho, Marikki

    2009-01-01

    Ski is an oncoprotein that negatively regulates transforming growth factor (TGF)-β signaling. It acts as a transcriptional co-repressor by binding to TGF-β signaling molecules, Smads. Efficient TGF-β signaling is facilitated by rapid proteasome-mediated degradation of Ski by TGF-β. Here we report that Ski is phosphorylated by Akt/PKB kinase. Akt phosphorylates Ski on a highly conserved Akt motif at threonine 458 both in vitro and in vivo. The phosphorylation of Ski at threonine 458 is induced by Akt pathway activators including insulin, insulin-like growth factor-1, and hepatocyte growth factor. The phosphorylation of Ski causes its destabilization and reduces Ski-mediated inhibition of expression of another negative regulator of TGF-β, Smad7. Induction of Smad7 levels leads to inactivation of TGF-β receptors and TGF-β signaling cascade, as indicated by reduced induction of TGF-β target p15. Therefore, Akt modulates TGF-β signaling by temporarily adjusting the levels of two TGF-β pathway negative regulators, Ski and Smad7. These novel findings demonstrate that Akt pathway activation directly impacts TGF-β pathway. PMID:19875456

  13. Signal Detection Analysis of Factors Associated with Diabetes among Semirural Mexican American Adults

    ERIC Educational Resources Information Center

    Hanni, K. D.; Ahn, D. A.; Winkleby, M. A.

    2013-01-01

    Signal detection analysis was used to evaluate a combination of sociodemographic, acculturation, mental health, health care, and chronic disease risk factors potentially associated with diabetes in a sample of 4,505 semirural Mexican American adults. Overall, 8.9% of adults had been diagnosed with diabetes. The analysis resulted in 12 mutually…

  14. Negative feedback regulation of TGF-beta signaling by the SnoN oncoprotein.

    PubMed

    Stroschein, S L; Wang, W; Zhou, S; Zhou, Q; Luo, K

    1999-10-22

    Smad proteins mediate transforming growth factor-beta (TGF-beta) signaling to regulate cell growth and differentiation. The SnoN oncoprotein was found to interact with Smad2 and Smad4 and to repress their abilities to activate transcription through recruitment of the transcriptional corepressor N-CoR. Immediately after TGF-beta stimulation, SnoN is rapidly degraded by the nuclear accumulation of Smad3, allowing the activation of TGF-beta target genes. By 2 hours, TGF-beta induces a marked increase in SnoN expression, resulting in termination of Smad-mediated transactivation. Thus, SnoN maintains the repressed state of TGF-beta-responsive genes in the absence of ligand and participates in negative feedback regulation of TGF-beta signaling.

  15. Signaling of pigment-dispersing factor (PDF) in the Madeira cockroach Rhyparobia maderae.

    PubMed

    Wei, Hongying; Yasar, Hanzey; Funk, Nico W; Giese, Maria; Baz, El-Sayed; Stengl, Monika

    2014-01-01

    The insect neuropeptide pigment-dispersing factor (PDF) is a functional ortholog of vasoactive intestinal polypeptide, the coupling factor of the mammalian circadian pacemaker. Despite of PDF's importance for synchronized circadian locomotor activity rhythms its signaling is not well understood. We studied PDF signaling in primary cell cultures of the accessory medulla, the circadian pacemaker of the Madeira cockroach. In Ca²⁺ imaging studies four types of PDF-responses were distinguished. In regularly bursting type 1 pacemakers PDF application resulted in dose-dependent long-lasting increases in Ca²⁺ baseline concentration and frequency of oscillating Ca²⁺ transients. Adenylyl cyclase antagonists prevented PDF-responses in type 1 cells, indicating that PDF signaled via elevation of intracellular cAMP levels. In contrast, in type 2 pacemakers PDF transiently raised intracellular Ca²⁺ levels even after blocking adenylyl cyclase activity. In patch clamp experiments the previously characterized types 1-4 could not be identified. Instead, PDF-responses were categorized according to ion channels affected. Application of PDF inhibited outward potassium or inward sodium currents, sometimes in the same neuron. In a comparison of Ca²⁺ imaging and patch clamp experiments we hypothesized that in type 1 cells PDF-dependent rises in cAMP concentrations block primarily outward K⁺ currents. Possibly, this PDF-dependent depolarization underlies PDF-dependent phase advances of pacemakers. Finally, we propose that PDF-dependent concomitant modulation of K⁺ and Na⁺ channels in coupled pacemakers causes ultradian membrane potential oscillations as prerequisite to efficient synchronization via resonance.

  16. Signaling of Pigment-Dispersing Factor (PDF) in the Madeira Cockroach Rhyparobia maderae

    PubMed Central

    Funk, Nico W.; Giese, Maria; Baz, El-Sayed; Stengl, Monika

    2014-01-01

    The insect neuropeptide pigment-dispersing factor (PDF) is a functional ortholog of vasoactive intestinal polypeptide, the coupling factor of the mammalian circadian pacemaker. Despite of PDF's importance for synchronized circadian locomotor activity rhythms its signaling is not well understood. We studied PDF signaling in primary cell cultures of the accessory medulla, the circadian pacemaker of the Madeira cockroach. In Ca2+ imaging studies four types of PDF-responses were distinguished. In regularly bursting type 1 pacemakers PDF application resulted in dose-dependent long-lasting increases in Ca2+ baseline concentration and frequency of oscillating Ca2+ transients. Adenylyl cyclase antagonists prevented PDF-responses in type 1 cells, indicating that PDF signaled via elevation of intracellular cAMP levels. In contrast, in type 2 pacemakers PDF transiently raised intracellular Ca2+ levels even after blocking adenylyl cyclase activity. In patch clamp experiments the previously characterized types 1–4 could not be identified. Instead, PDF-responses were categorized according to ion channels affected. Application of PDF inhibited outward potassium or inward sodium currents, sometimes in the same neuron. In a comparison of Ca2+ imaging and patch clamp experiments we hypothesized that in type 1 cells PDF-dependent rises in cAMP concentrations block primarily outward K+ currents. Possibly, this PDF-dependent depolarization underlies PDF-dependent phase advances of pacemakers. Finally, we propose that PDF-dependent concomitant modulation of K+ and Na+ channels in coupled pacemakers causes ultradian membrane potential oscillations as prerequisite to efficient synchronization via resonance. PMID:25269074

  17. Matrix remodeling maintains ESC self-renewal by activating Stat3

    PubMed Central

    Przybyla, Laralynne M.; Theunissen, Thorold W.; Jaenisch, Rudolf; Voldman, Joel

    2013-01-01

    While a variety of natural and synthetic matrices have been used to influence embryonic stem cell (ESC) self-renewal or differentiation, and ESCs also deposit a rich matrix of their own, the mechanisms behind how extracellular matrix affects cell fate are largely unexplored. The ESC matrix is continuously remodeled by matrix metalloproteinases (MMPs), a process that we find is enhanced by the presence of mouse embryonic fibroblast feeders in a paracrine manner. Matrix remodeling by MMPs aids in the self-renewal of ESCs, as inhibition of MMPs inhibits the ability of ESCs to self-renew. We also find that addition of the interstitial collagenase MMP1 is sufficient to maintain long-term LIF-independent mESC self-renewal in a dose-dependent manner. This remarkable ability is due to the presence of endogenously produced self-renewal-inducing signals, including the LIF-family ligand CNTF, that are normally trapped within the ECM and become exposed upon MMP-induced matrix remodeling to signal through JAK and Stat3. These results uncover a new role for feeder cells in maintaining self-renewal and show that mESCs normally produce sufficient levels of autocrine-acting pro-self-renewal ligands. PMID:23404867

  18. MOSFET analog memory circuit achieves long duration signal storage

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Memory circuit maintains the signal voltage at the output of an analog signal amplifier when the input signal is interrupted or removed. The circuit uses MOSFET /Metal Oxide Semiconductor Field Effect Transistor/ devices as voltage-controlled switches, triggered by an external voltage-sensing device.

  19. Factors influencing treatment decision-making for maintaining or extracting compromised teeth.

    PubMed

    Lang-Hua, Bich Hue; McGrath, Colman P J; Lo, Edward C M; Lang, Niklaus P

    2014-01-01

    To evaluate treatment decision-making with respect to maintaining periodontally compromised teeth among dentists with or without postgraduate qualifications in implant dentistry. A series of patient scenarios with varying degrees of periodontal disease levels was presented to dental practitioners. Practitioners' decision-making outcome was determined, and intention to retain the compromised teeth was analyzed in bivariate and regression analyses (accounting for postgraduate implant training, gender, years in dental practice, and implant placement experience). This study involved 30 dental practitioners with postgraduate implant qualifications (GDPP), 33 dental practitioners without postgraduate implant qualifications (GDP), and 27 practitioners undergoing training for postgraduate implant qualifications (GDPT). Variations in treatment decision-making were evident between the three groups. Differences in treatment approaches to retaining compromised teeth were apparent. Furthermore, variations in rehabilitation of extracted scenarios existed in terms of use of implant and number of implants need for rehabilitation. Accounting for dentist and practice factors in regression analyses, GDPP/GDPT were three times as likely to retain periodontally compromised upper molar, with or without pain, compared to GDP (without pain OR 3.10, 95%CI 1.04, 10.62 P = 0.04; with pain OR 3.08, 95%CI 1.09, 8.14 P = 0.03). Variations in treatment decision-making with respect to retaining periodontally compromised teeth exist between dental practitioners with and those without postgraduate training in implant dentistry. Furthermore differences in management approaches in how they would retain the teeth or rehabilitate the dental arch were apparent. © 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

  20. A dendritic cell-stromal axis maintains immune responses in lymph nodes

    PubMed Central

    Kumar, Varsha; Dasoveanu, Dragos C.; Chyou, Susan; Tzeng, Te-Chen; Rozo, Cristina; Liang, Yong; Stohl, William; Fu, Yang-Xin; Ruddle, Nancy; Lu, Theresa T.

    2015-01-01

    Summary Within secondary lymphoid tissues, stromal reticular cells support lymphocyte function, and targeting reticular cells is a potential strategy for controlling pathogenic lymphocytes in disease. However, the mechanisms that regulate reticular cell function are not well understood. Here we found that during an immune response in lymph nodes, dendritic cells (DCs) maintain reticular cell survival in multiple compartments. DC-derived lymphotoxin beta receptor (LTβR) ligands were critical mediators, and LTβR signaling on reticular cells mediated cell survival by modulating podoplanin (PDPN). PDPN modulated integrin-mediated cell adhesion, which maintained cell survival. This DC-stromal axis maintained lymphocyte survival and the ongoing immune response. Our findings provide insight into the functions of DCs, LTβR, and PDPN and delineate a DC-stromal axis that can potentially be targeted in autoimmune or lymphoproliferative diseases. PMID:25902483

  1. Cellular signaling by fibroblast growth factors (FGFs) and their receptors (FGFRs) in male reproduction.

    PubMed

    Cotton, Leanne M; O'Bryan, Moira K; Hinton, Barry T

    2008-04-01

    The major function of the reproductive system is to ensure the survival of the species by passing on hereditary traits from one generation to the next. This is accomplished through the production of gametes and the generation of hormones that function in the maturation and regulation of the reproductive system. It is well established that normal development and function of the male reproductive system is mediated by endocrine and paracrine signaling pathways. Fibroblast growth factors (FGFs), their receptors (FGFRs), and signaling cascades have been implicated in a diverse range of cellular processes including: proliferation, apoptosis, cell survival, chemotaxis, cell adhesion, motility, and differentiation. The maintenance and regulation of correct FGF signaling is evident from human and mouse genetic studies which demonstrate that mutations leading to disruption of FGF signaling cause a variety of developmental disorders including dominant skeletal diseases, infertility, and cancer. Over the course of this review, we will provide evidence for differential expression of FGFs/FGFRs in the testis, male germ cells, the epididymis, the seminal vesicle, and the prostate. We will show that this signaling cascade has an important role in sperm development and maturation. Furthermore, we will demonstrate that FGF/FGFR signaling is essential for normal epididymal function and prostate development. To this end, we will provide evidence for the involvement of the FGF signaling system in the regulation and maintenance of the male reproductive system.

  2. Transforming growth factor (TGF)beta, fibroblast growth factor (FGF) and retinoid signalling pathways promote pancreatic exocrine gene expression in mouse embryonic stem cells.

    PubMed Central

    Skoudy, Anouchka; Rovira, Meritxell; Savatier, Pierre; Martin, Franz; León-Quinto, Trinidad; Soria, Bernat; Real, Francisco X

    2004-01-01

    Extracellular signalling cues play a major role in the activation of differentiation programmes. Mouse embryonic stem (ES) cells are pluripotent and can differentiate into a wide variety of specialized cells. Recently, protocols designed to induce endocrine pancreatic differentiation in vitro have been designed but little information is currently available concerning the potential of ES cells to differentiate into acinar pancreatic cells. By using conditioned media of cultured foetal pancreatic rudiments, we demonstrate that ES cells can respond in vitro to signalling pathways involved in exocrine development and differentiation. In particular, modulation of the hedgehog, transforming growth factor beta, retinoid, and fibroblast growth factor pathways in ES cell-derived embryoid bodies (EB) resulted in increased levels of transcripts encoding pancreatic transcription factors and cytodifferentiation markers, as demonstrated by RT-PCR. In EB undergoing spontaneous differentiation, expression of the majority of the acinar genes (i.e. amylase, carboxypeptidase A and elastase) was induced after the expression of endocrine genes, as occurs in vivo during development. These data indicate that ES cells can undergo exocrine pancreatic differentiation with a kinetic pattern of expression reminiscent of pancreas development in vivo and that ES cells can be coaxed to express an acinar phenotype by activation of signalling pathways known to play a role in pancreatic development and differentiation. PMID:14733613

  3. Research on the Additional Secondary Phase Factor for Automatic Identification System Signals Transmitted over a Rough Sea Surface

    PubMed Central

    Zhang, Shufang; Sun, Xiaowen

    2018-01-01

    This paper investigates the Additional Secondary Phase Factor (ASF) characteristics of Automatic Identification System (AIS) signals spreading over a rough sea surface. According to the change of the ASFs for AIS signals in different signal form, the influences of the different propagation conditions on the ASFs are analyzed. The expression, numerical calculation, and simulation analysis of the ASFs of AIS signal are performed in the rough sea surface. The results contribute to the high-accuracy propagation delay measurement of AIS signals spreading over the rough sea surface as, well as providing a reference for reliable communication link design in marine engineering for Very High Frequency (VHF) signals. PMID:29462995

  4. The Drosophila T-box transcription factor Midline functions within the Notch–Delta signaling pathway to specify sensory organ precursor cell fates and regulates cell survival within the eye imaginal disc

    PubMed Central

    Das, Sudeshna; Chen, Q. Brent; Saucier, Joseph D.; Drescher, Brandon; Zong, Yan; Morgan, Sarah; Forstall, John; Meriwether, Andrew; Toranzo, Randy; Leal, Sandra M.

    2014-01-01

    We report that the T-box transcription factor Midline (Mid), an evolutionary conserved homolog of the vertebrate Tbx20 protein, functions within the Notch–Delta signaling pathway essential for specifying the fates of sensory organ precursor cells. This complements an established history of research showing that Mid regulates the cell-fate specification of diverse cell types within the developing heart, epidermis and central nervous system. Tbx20 has been detected in diverse neuronal and epithelial cells of embryonic eye tissues in both mice and humans. However, the mechanisms by which either Mid or Tbx20 function to regulate cell-fate specification or other critical aspects of eye development including cell survival have not yet been elucidated. We have also gathered preliminary evidence suggesting that Mid may play an indirect, but vital role in selecting SOP cells within the third-instar larval eye disc by regulating the expression of the proneural gene atonal. During subsequent pupal stages, Mid specifies SOP cell fates as a member of the Notch–Delta signaling hierarchy and is essential for maintaining cell viability within by inhibiting apoptotic pathways. We present several new hypotheses that seek to understand the role of Mid in regulating developmental processes downstream of the Notch receptor that are critical for specifying unique cell fates, patterning the adult eye and maintaining cellular homeostasis during eye disc morphogenesis. PMID:23962751

  5. Lysophosphatidylcholine up-regulates human endothelial nitric oxide synthase gene transactivity by c-Jun N-terminal kinase signalling pathway

    PubMed Central

    Xing, Feiyue; Liu, Jing; Mo, Yongyan; Liu, Zhifeng; Qin, Qinghe; Wang, Jingzhen; Fan, Zhenhua; Long, Yutian; Liu, Na; Zhao, Kesen; Jiang, Yong

    2009-01-01

    Human endothelial nitric oxide synthase (eNOS) plays a pivotal role in maintaining blood pressure homeostasis and vascular integrity. It has recently been reported that mitogen-activated protein kinases (MAPKs) are intimately implicated in expression of eNOS. However detailed mechanism mediated by them remains to be clarified. In this study, eNOS gene transactivity in human umbilical vein endothelial cells was up-regulated by stimulation of lysophosphatidylcholine (LPC). The stimulation of LPC highly activated both extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK), with differences in the dynamic processes of activation between them. Unexpectedly, p38 MAPK could not be activated by the stimulation of LPC. The activation of JNK signalling pathway by overexpression of JNK or its upstream kinase active mutant up-regulated the transactivity of eNOS significantly, but the activation of p38 signalling pathway down-regulated it largely. The inhibition of either ERK1/2 or JNK signalling pathway by kinase-selective inhibitors could markedly block the induction of the transactivity by LPC. It was observed by electrophoretic mobility shift assay that LPC stimulated both SP1 and AP1 DNA binding activity to go up. Additionally using decoy oligonucleotides proved that SP1 was necessary for maintaining the basal or stimulated transactivity, whereas AP1 contributed mainly to the increase of the stimulated transactivity. These findings indicate that the up-regulation of the eNOS gene transactivity by LPC involves the enhancement of SP1 transcription factor by the activation of JNK and ERK1/2 signalling pathways and AP1 transcription factor by the activation of JNK signalling pathway. PMID:18624763

  6. Hypoxia-Inducible Factors Link Iron Homeostasis and Erythropoiesis

    PubMed Central

    Shah, Yatrik M.; Xie, Liwei

    2014-01-01

    Iron is required for efficient oxygen transport, and hypoxia signaling links erythropoiesis with iron homeostasis. Hypoxia induces a highly conserved signaling pathway in cells under conditions of low O2. One component of this pathway, hypoxia-inducible factor (HIF), is a transcription factor that is highly active in hypoxic cells. The first HIF target gene characterized was EPO, which encodes erythropoietin—a glycoprotein hormone that controls erythropoiesis. The past decade has led to fundamental advances in our understanding of how hypoxia regulates iron levels to support erythropoiesis and maintain systemic iron homeostasis. We review the cell-type specific effects of hypoxia and HIFs in adaptive response to changes in oxygen and iron availability, as well as potential uses of HIF modulators for patients with iron-related disorders. PMID:24389303

  7. Foxo Transcription Factors Blunt Cardiac Hypertrophy by Inhibiting Calcineurin Signaling

    PubMed Central

    Ni, Yan G.; Berenji, Kambeez; Wang, Na; Oh, Misook; Sachan, Nita; Dey, Asim; Cheng, Jun; Lu, Guangrong; Morris, David J.; Castrillon, Diego H.; Gerard, Robert D.; Rothermel, Beverly A.; Hill, Joseph A.

    2014-01-01

    Background Cellular hypertrophy requires coordinated regulation of progrowth and antigrowth mechanisms. In cultured neonatal cardiomyocytes, Foxo transcription factors trigger an atrophy-related gene program that counters hypertrophic growth. However, downstream molecular events are not yet well defined. Methods and Results Here, we report that expression of either Foxo1 or Foxo3 in cardiomyocytes attenuates calcineurin phosphatase activity and inhibits agonist-induced hypertrophic growth. Consistent with these results, Foxo proteins decrease calcineurin phosphatase activity and repress both basal and hypertrophic agonist-induced expression of MCIP1.4, a direct downstream target of the calcineurin/NFAT pathway. Furthermore, hearts from Foxo3-null mice exhibit increased MCIP1.4 abundance and a hypertrophic phenotype with normal systolic function at baseline. Together, these results suggest that Foxo proteins repress cardiac growth at least in part through inhibition of the calcineurin/NFAT pathway. Given that hypertrophic growth of the heart occurs in multiple contexts, our findings also suggest that certain hypertrophic signals are capable of overriding the antigrowth program induced by Foxo. Consistent with this, multiple hypertrophic agonists triggered inactivation of Foxo proteins in cardiomyocytes through a mechanism requiring the PI3K/Akt pathway. In addition, both Foxo1 and Foxo3 are phosphorylated and consequently inactivated in hearts undergoing hypertrophic growth induced by hemodynamic stress. Conclusions This study suggests that inhibition of the calcineurin/NFAT signaling cascade by Foxo and release of this repressive action by the PI3K/Akt pathway are important mechanisms whereby Foxo factors govern cell growth in the heart. PMID:16952979

  8. Foxo transcription factors blunt cardiac hypertrophy by inhibiting calcineurin signaling.

    PubMed

    Ni, Yan G; Berenji, Kambeez; Wang, Na; Oh, Misook; Sachan, Nita; Dey, Asim; Cheng, Jun; Lu, Guangrong; Morris, David J; Castrillon, Diego H; Gerard, Robert D; Rothermel, Beverly A; Hill, Joseph A

    2006-09-12

    Cellular hypertrophy requires coordinated regulation of progrowth and antigrowth mechanisms. In cultured neonatal cardiomyocytes, Foxo transcription factors trigger an atrophy-related gene program that counters hypertrophic growth. However, downstream molecular events are not yet well defined. Here, we report that expression of either Foxo1 or Foxo3 in cardiomyocytes attenuates calcineurin phosphatase activity and inhibits agonist-induced hypertrophic growth. Consistent with these results, Foxo proteins decrease calcineurin phosphatase activity and repress both basal and hypertrophic agonist-induced expression of MCIP1.4, a direct downstream target of the calcineurin/NFAT pathway. Furthermore, hearts from Foxo3-null mice exhibit increased MCIP1.4 abundance and a hypertrophic phenotype with normal systolic function at baseline. Together, these results suggest that Foxo proteins repress cardiac growth at least in part through inhibition of the calcineurin/NFAT pathway. Given that hypertrophic growth of the heart occurs in multiple contexts, our findings also suggest that certain hypertrophic signals are capable of overriding the antigrowth program induced by Foxo. Consistent with this, multiple hypertrophic agonists triggered inactivation of Foxo proteins in cardiomyocytes through a mechanism requiring the PI3K/Akt pathway. In addition, both Foxo1 and Foxo3 are phosphorylated and consequently inactivated in hearts undergoing hypertrophic growth induced by hemodynamic stress. This study suggests that inhibition of the calcineurin/NFAT signaling cascade by Foxo and release of this repressive action by the PI3K/Akt pathway are important mechanisms whereby Foxo factors govern cell growth in the heart.

  9. TRPM7 maintains progenitor-like features of neuroblastoma cells: implications for metastasis formation

    PubMed Central

    Middelbeek, Jeroen; Kamermans, Alwin; Kuipers, Arthur J.; Hoogerbrugge, Peter M.; Jalink, Kees; van Leeuwen, Frank N.

    2015-01-01

    Neuroblastoma is an embryonal tumor derived from poorly differentiated neural crest cells. Current research is aimed at identifying the molecular mechanisms that maintain the progenitor state of neuroblastoma cells and to develop novel therapeutic strategies that induce neuroblastoma cell differentiation. Mechanisms controlling neural crest development are typically dysregulated during neuroblastoma progression, and provide an appealing starting point for drug target discovery. Transcriptional programs involved in neural crest development act as a context dependent gene regulatory network. In addition to BMP, Wnt and Notch signaling, activation of developmental gene expression programs depends on the physical characteristics of the tissue microenvironment. TRPM7, a mechanically regulated TRP channel with kinase activity, was previously found essential for embryogenesis and the maintenance of undifferentiated neural crest progenitors. Hence, we hypothesized that TRPM7 may preserve progenitor-like, metastatic features of neuroblastoma cells. Using multiple neuroblastoma cell models, we demonstrate that TRPM7 expression closely associates with the migratory and metastatic properties of neuroblastoma cells in vitro and in vivo. Moreover, microarray-based expression profiling on control and TRPM7 shRNA transduced neuroblastoma cells indicates that TRPM7 controls a developmental transcriptional program involving the transcription factor SNAI2. Overall, our data indicate that TRPM7 contributes to neuroblastoma progression by maintaining progenitor-like features. PMID:25797249

  10. Reduced expression of the epidermal growth factor signaling system in preeclampsia.

    PubMed

    Armant, D R; Fritz, R; Kilburn, B A; Kim, Y M; Nien, J K; Maihle, N J; Romero, R; Leach, R E

    2015-03-01

    The epidermal growth factor (EGF) signaling system regulates trophoblast differentiation, and its disruption could contribute to perinatal disease. We hypothesized that this pathway is altered in preeclampsia, a disorder associated with trophoblast apoptosis and failure to invade and remodel the uterine spiral arteries. Six EGF family peptides and a truncated EGF receptor splice variant (p110/EGFR) were examined using immunohistochemistry in the trophoblast of placentas (N = 76) from women with preeclampsia, and compared to placentas from women of similar gestational age (GA) with preterm labor (PTL) or small for gestational age (SGA) fetuses, as well as normal term placentas. EGF, transforming growth factor-α (TGFA), and heparin-binding EGF-like growth factor (HBEGF) were evaluated using ELISA in maternal plasma from another 20 pregnancies with or without preeclampsia. Cell death was evaluated in the HTR-8/SVneo human cytotrophoblast cell line using TUNEL to evaluate the protective effects of EGF peptides. Trophoblast HBEGF, TGFA, and EGF were significantly reduced in preeclampsia compared to PTL and SGA, while p110/EGFR accumulated significantly on the surface of the chorionic villi (p < 0.05). Plasma EGF levels were significantly decreased in preeclamptic patients, compared to non-preeclamptic patients (p < 0.05). HBEGF, EGF, TGFA, epiregulin, and betacellulin each blocked cytotrophoblast cell death in vitro (p < 0.05). Three members of the EGF family are dysregulated in placentas with preeclampsia, whereas p110/EGFR, a potential EGF receptor antagonist, is overexpressed. These findings are consistent with the concept that disruption of the EGF signaling system contributes to aberrant trophoblast development associated with preeclampsia. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Reduced Expression of the Epidermal Growth Factor Signaling System in Preeclampsia

    PubMed Central

    Armant, D. Randall; FRITZ, Rani; KILBURN, Brian A.; KIM, Yeon Mee; NIEN, Jyh Kae; MAIHLE, Nita J.; ROMERO, Roberto; LEACH, Richard E.

    2014-01-01

    Introduction The epidermal growth factor (EGF) signaling system regulates trophoblast differentiation, and its disruption could contribute to perinatal disease. We hypothesized that this pathway is altered in preeclampsia, a disorder associated with trophoblast apoptosis and failure to invade and remodel the uterine spiral arteries. Methods Six EGF family peptides and a truncated EGF receptor splice variant (p110/EGFR) were examined using immunocytochemistry in the trophoblast of placentas (N=76) from women with preeclampsia, and compared to placentas from women of similar gestational age (GA) with preterm labor (PTL) or small for gestational age (SGA) fetuses, as well as normal term placentas. EGF, transforming growth factor-α (TGFA), and heparin-binding EGF-like growth factor (HBEGF) were evaluated using ELISA in maternal plasma from another 20 pregnancies with or without preeclampsia. Cell death was evaluated in the HTR-8/SVneo human cytotrophoblast cell line using TUNEL to evaluate the protective effects of EGF peptides. Results Trophoblast HBEGF, TGFA, and EGF were significantly reduced in preeclampsia compared to PTL and SGA, while p110/EGFR accumulated significantly on the surface of the chorionic villi (p<0.05). Plasma EGF levels were significantly decreased in preeclamptic patients, compared to non-preeclamptic patients (p<0.05). HBEGF, EGF, TGFA, epiregulin, and betacellulin each blocked cytotrophoblast cell death in vitro (p< 0.05). Discussion Three members of the EGF family are dysregulated in placentas with preeclampsia, whereas p110/EGFR, a potential EGF receptor antagonist, is overexpressed. These findings are consistent with the concept that disruption of the EGF signaling system contributes to aberrant trophoblast development associated with preeclampsia. PMID:25589361

  12. Maintaining Traditions: A Qualitative Study of Early Childhood Caries Risk and Protective Factors in an Indigenous Community

    PubMed Central

    Levin, Ana; Sokal-Gutierrez, Karen; Hargrave, Anita; Funsch, Elizabeth; Hoeft, Kristin S.

    2017-01-01

    In lower middle-income economies (LMIE), the nutrition transition from traditional diets to sugary foods and beverages has contributed to widespread early childhood dental caries. This qualitative study explores perceived risk and protective factors, and overall experiences of early childhood nutrition and oral health in indigenous Ecuadorian families participating in a community-based oral health and nutrition intervention. Dental exams of 698 children age 6 months through 6 years determined each child’s caries burden. A convenience sample of 18 “outlier” families was identified: low-caries children with ≤2 carious teeth vs. high-caries children with ≥10 carious teeth. Semi-structured in-depth interviews with parents/caregivers explored the child’s diet, dental habits, and family factors related to nutrition and oral health. Interviews were transcribed and thematically analyzed using grounded theory. In the high-caries families, proximity to highway and stores, consumption of processed-food, and low parental monitoring of child behavior were identified as risk factors for ECC (early childhood caries). In the low-caries families, protective factors included harvesting and consuming food from the family farm, remote geography, and greater parental monitoring of child behavior. The study results suggest that maintaining traditional family farms and authoritative parenting to avoid processed foods/drinks and ensure tooth brushing could improve early childhood nutrition and oral health. PMID:28800116

  13. Maintaining Traditions: A Qualitative Study of Early Childhood Caries Risk and Protective Factors in an Indigenous Community.

    PubMed

    Levin, Ana; Sokal-Gutierrez, Karen; Hargrave, Anita; Funsch, Elizabeth; Hoeft, Kristin S

    2017-08-11

    In lower middle-income economies (LMIE), the nutrition transition from traditional diets to sugary foods and beverages has contributed to widespread early childhood dental caries. This qualitative study explores perceived risk and protective factors, and overall experiences of early childhood nutrition and oral health in indigenous Ecuadorian families participating in a community-based oral health and nutrition intervention. Dental exams of 698 children age 6 months through 6 years determined each child's caries burden. A convenience sample of 18 "outlier" families was identified: low-caries children with ≤2 carious teeth vs. high-caries children with ≥10 carious teeth. Semi-structured in-depth interviews with parents/caregivers explored the child's diet, dental habits, and family factors related to nutrition and oral health. Interviews were transcribed and thematically analyzed using grounded theory. In the high-caries families, proximity to highway and stores, consumption of processed-food, and low parental monitoring of child behavior were identified as risk factors for ECC (early childhood caries). In the low-caries families, protective factors included harvesting and consuming food from the family farm, remote geography, and greater parental monitoring of child behavior. The study results suggest that maintaining traditional family farms and authoritative parenting to avoid processed foods/drinks and ensure tooth brushing could improve early childhood nutrition and oral health.

  14. Oral Application of Magnesium-L-Threonate Attenuates Vincristine-induced Allodynia and Hyperalgesia by Normalization of Tumor Necrosis Factor-α/Nuclear Factor-κB Signaling.

    PubMed

    Xu, Ting; Li, Dai; Zhou, Xin; Ouyang, Han-Dong; Zhou, Li-Jun; Zhou, Hang; Zhang, Hong-Mei; Wei, Xu-Hong; Liu, Guosong; Liu, Xian-Guo

    2017-06-01

    Antineoplastic agents, including vincristine, often induce neuropathic pain and magnesium deficiency clinically, but the causal link between them has not been determined. No drug is available for treating this form of neuropathic pain. Injection of vincristine (0.1 mg · kg · day, intraperitoneally, for 10 days) was used to induce nociceptive sensitization, which was accessed with von Frey hairs and the plantar tester in adult male Sprague-Dawley rats. Magnesium-L- threonate was administered through drinking water (604 mg · kg · day). Extracellular and intracellular free Mg were measured by Calmagite chromometry and flow cytometry. Molecular biologic and electrophysiologic experiments were performed to expose the underlying mechanisms. Vincristine injection induced allodynia and hyperalgesia (n = 12), activated tumor necrosis factor-α/nuclear factor-κB signaling, and reduced free Mg in cerebrospinal fluid by 21.7 ± 6.3% (mean ± SD; n = 13) and in dorsal root ganglion neurons by 27 ± 6% (n = 11). Reducing Mg activated tumor necrosis factor-α/nuclear factor-κB signaling in cultured dorsal root ganglion neurons. Oral application of magnesium-L-threonate prevented magnesium deficiency and attenuated both activation of tumor necrosis factor-α/nuclear factor-κB signaling and nociceptive sensitization (n = 12). Mechanistically, vincristine induced long-term potentiation at C-fiber synapses, up-regulated N-methyl-D-aspartate receptor type 2B subunit of N-methyl-D-aspartate receptor, and led to peptidergic C-fiber sprouting in spinal dorsal horn (n = 6 each). The vincristine-induced pathologic plasticity was blocked by intrathecal injection of nuclear factor-κB inhibitor (n = 6), mimicked by tumor necrosis factor-α, and substantially prevented by oral magnesium-L-threonate (n = 5). Vincristine may activate tumor necrosis factor-α/nuclear factor-κB pathway by reduction of intracellular magnesium, leading to spinal pathologic plasticity and

  15. Subcellular Redox Signaling.

    PubMed

    Zhu, Liping; Lu, Yankai; Zhang, Jiwei; Hu, Qinghua

    2017-01-01

    Oxidative and antioxidative system of cells and tissues maintains a balanced state under physiological conditions. A disruption in this balance of redox status has been associated with numerous pathological processes. Reactive oxygen species (ROS) as a major redox signaling generates in a spatiotemporally dependent manner. Subcellular organelles such as mitochondria, endoplasmic reticulum, plasma membrane and nuclei contribute to the production of ROS. In addition to downstream effects of ROS signaling regulated by average ROS changes in cytoplasm, whether subcelluar ROS mediate biological effect(s) has drawn greater attentions. With the advance in redox-sensitive probes targeted to different subcellular compartments, the investigation of subcellular ROS signaling and its associated cellular function has become feasible. In this review, we discuss the subcellular ROS signaling, with particular focus on mechanisms of subcellular ROS production and its downstream effects.

  16. Signal transduction by beta1 integrin receptors in human chondrocytes in vitro: collaboration with the insulin-like growth factor-I receptor.

    PubMed

    Shakibaei, M; John, T; De Souza, P; Rahmanzadeh, R; Merker, H J

    1999-09-15

    We have examined the mechanism by which collagen-binding integrins co-operate with insulin-like growth factor-I (IGF-I) receptors (IGF-IR) to regulate chondrocyte phenotype and differentiation. Adhesion of chondrocytes to anti-beta1 integrin antibodies or collagen type II leads to phosphorylation of cytoskeletal and signalling proteins localized at focal adhesions, including alpha-actinin, vinculin, paxillin and focal adhesion kinase (FAK). These stimulate docking proteins such as Shc (Src-homology collagen). Moreover, exposure of collagen type II-cultured chondrocytes to IGF-I leads to co-immunoprecipitation of Shc protein with the IGF-IR and with beta1, alpha1 and alpha5 integrins, but not with alpha3 integrin. Shc then associates with growth factor receptor-bound protein 2 (Grb2), an adaptor protein and extracellular signal-regulated kinase. The expression of the docking protein Shc occurs only when chondrocytes are bound to collagen type II or integrin antibodies and increases when IGF-I is added, suggesting a collaboration between integrins and growth factors in a common/shared biochemical signalling pathway. Furthermore, these results indicate that focal adhesion assembly may facilitate signalling via Shc, a potential common target for signal integration between integrin and growth-factor signalling regulatory pathways. Thus, the collagen-binding integrins and IGF-IR co-operate to regulate focal adhesion components and these signalling pathways have common targets (Shc-Grb2 complex) in subcellular compartments, thereby linking to the Ras-mitogen-activated protein kinase signalling pathway. These events may play a role during chondrocyte differentiation.

  17. Antagonistic regulation of p57kip2 by Hes/Hey downstream of Notch signaling and muscle regulatory factors regulates skeletal muscle growth arrest.

    PubMed

    Zalc, Antoine; Hayashi, Shinichiro; Auradé, Frédéric; Bröhl, Dominique; Chang, Ted; Mademtzoglou, Despoina; Mourikis, Philippos; Yao, Zizhen; Cao, Yi; Birchmeier, Carmen; Relaix, Frédéric

    2014-07-01

    A central question in development is to define how the equilibrium between cell proliferation and differentiation is temporally and spatially regulated during tissue formation. Here, we address how interactions between cyclin-dependent kinase inhibitors essential for myogenic growth arrest (p21(cip1) and p57(kip2)), the Notch pathway and myogenic regulatory factors (MRFs) orchestrate the proliferation, specification and differentiation of muscle progenitor cells. We first show that cell cycle exit and myogenic differentiation can be uncoupled. In addition, we establish that skeletal muscle progenitor cells require Notch signaling to maintain their cycling status. Using several mouse models combined with ex vivo studies, we demonstrate that Notch signaling is required to repress p21(cip1) and p57(kip2) expression in muscle progenitor cells. Finally, we identify a muscle-specific regulatory element of p57(kip2) directly activated by MRFs in myoblasts but repressed by the Notch targets Hes1/Hey1 in progenitor cells. We propose a molecular mechanism whereby information provided by Hes/Hey downstream of Notch as well as MRF activities are integrated at the level of the p57(kip2) enhancer to regulate the decision between progenitor cell maintenance and muscle differentiation. © 2014. Published by The Company of Biologists Ltd.

  18. Arsenite suppression of BMP signaling in human keratinocytes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Phillips, Marjorie A.; Qin, Qin; Hu, Qin

    2013-06-15

    Arsenic, a human skin carcinogen, suppresses differentiation of cultured keratinocytes. Exploring the mechanism of this suppression revealed that BMP-6 greatly increased levels of mRNA for keratins 1 and 10, two of the earliest differentiation markers expressed, a process prevented by co-treatment with arsenite. BMP also stimulated, and arsenite suppressed, mRNA for FOXN1, an important transcription factor driving early keratinocyte differentiation. Keratin mRNAs increased slowly after BMP-6 addition, suggesting they are indirect transcriptional targets. Inhibition of Notch1 activation blocked BMP induction of keratins 1 and 10, while FOXN1 induction was largely unaffected. Supporting a requirement for Notch1 signaling in keratin induction,more » BMP increased levels of activated Notch1, which was blocked by arsenite. BMP also greatly decreased active ERK, while co-treatment with arsenite maintained active ERK. Inhibition of ERK signaling mimicked BMP by inducing keratin and FOXN1 mRNAs and by increasing active Notch1, effects blocked by arsenite. Of 6 dual-specificity phosphatases (DUSPs) targeting ERK, two were induced by BMP unless prevented by simultaneous exposure to arsenite and EGF. Knockdown of DUSP2 or DUSP14 using shRNAs greatly reduced FOXN1 and keratins 1 and 10 mRNA levels and their induction by BMP. Knockdown also decreased activated Notch1, keratin 1 and keratin 10 protein levels, both in the presence and absence of BMP. Thus, one of the earliest effects of BMP is induction of DUSPs, which increases FOXN1 transcription factor and activates Notch1, both required for keratin gene expression. Arsenite prevents this cascade by maintaining ERK signaling, at least in part by suppressing DUSP expression. - Highlights: • BMP induces FOXN1 transcription. • BMP induces DUSP2 and DUSP14, suppressing ERK activation. • Arsenite suppresses levels of phosphorylated Smad1/5 and FOXN1 and DUSP mRNA. • These actions rationalize arsenite suppression of

  19. Mitochondrial genome-maintaining activity of mouse mitochondrial transcription factor A and its transcript isoform in Saccharomyces cerevisiae.

    PubMed

    Yoon, Young Geol; Koob, Michael D; Yoo, Young Hyun

    2011-09-15

    Mitochondrial transcription factor A (Tfam) binds to and organizes mitochondrial DNA (mtDNA) genome into a mitochondrial nucleoid (mt-nucleoid) structure, which is necessary for mtDNA transcription and maintenance. Here, we demonstrate the mtDNA-organizing activity of mouse Tfam and its transcript isoform (Tfam(iso)), which has a smaller high-mobility group (HMG)-box1 domain, using a yeast model system that contains a deletion of the yeast homolog of mouse Tfam protein, Abf2p. When the mouse Tfam genes were introduced into the ABF2 locus of yeast genome, the corresponding mouse proteins, Tfam and Tfam(iso), can functionally replace the yeast Abf2p and support mtDNA maintenance and mitochondrial biogenesis in yeast. Growth properties, mtDNA content and mitochondrial protein levels of genes encoded in the mtDNA were comparable in the strains expressing mouse proteins and the wild-type yeast strain, indicating that the proteins have robust mtDNA-maintaining and -expressing function in yeast mitochondria. These results imply that the mtDNA-organizing activities of the mouse mt-nucleoid proteins are structurally and evolutionary conserved, thus they can maintain the mtDNA of distantly related and distinctively different species, such as yeast. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Transforming growth factor β-induced expression of chondroitin sulfate proteoglycans is mediated through non-Smad signaling pathways.

    PubMed

    Jahan, Naima; Hannila, Sari S

    2015-01-01

    The expression of chondroitin sulfate proteoglycans (CSPGs) by reactive astrocytes is a major factor contributing to glial scarring and regenerative failure after spinal cord injury, but the molecular mechanisms underlying CSPG expression remain largely undefined. One contributing factor is transforming growth factor β (TGFβ), which is upregulated after injury and has been shown to induce expression of CSPGs in vitro. TGFβ typically mediates its effects through the Smad2/3 signaling pathway, and it has been suggested that this pathway is responsible for CSPG expression. However, there is evidence that TGFβ can also activate non-Smad signaling pathways. In this study, we report that TGFβ-induced expression of three different CSPGs--neurocan, brevican, and aggrecan--is mediated through non-Smad signaling pathways. We observed significant increases in TGFβ-induced expression of neurocan, brevican, and aggrecan following siRNA knockdown of Smad2 or Smad4, which indicates that Smad signaling is not required for the expression of these CSPGs. In addition, we show that neurocan, aggrecan, and brevican levels are significantly reduced when TGFβ is administered in the presence of either the PI3K inhibitor LY294002 or the mTOR inhibitor rapamycin, but not the MEK1/2 inhibitor U0126. This suggests that TGFβ mediates this effect through non-Smad-dependent activation of the PI3K-Akt-mTOR signaling pathway, and targeting this pathway may therefore be an effective means of reducing CSPG expression in the injured CNS. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. DACH1 inhibits transforming growth factor-beta signaling through binding Smad4.

    PubMed

    Wu, Kongming; Yang, Ying; Wang, Chenguang; Davoli, Maria A; D'Amico, Mark; Li, Anping; Cveklova, Kveta; Kozmik, Zbynek; Lisanti, Michael P; Russell, Robert G; Cvekl, Ales; Pestell, Richard G

    2003-12-19

    The vertebrate homologues of Drosophila dachsund, DACH1 and DACH2, have been implicated as important regulatory genes in development. DACH1 plays a role in retinal and pituitary precursor cell proliferation and DACH2 plays a specific role in myogenesis. DACH proteins contain a domain (DS domain) that is conserved with the proto-oncogenes Ski and Sno. Since the Ski/Sno proto-oncogenes repress AP-1 and SMAD signaling, we hypothesized that DACH1 might play a similar cellular function. Herein, DACH1 was found to be expressed in breast cancer cell lines and to inhibit transforming growth factor-beta (TGF-beta)-induced apoptosis. DACH1 repressed TGF-beta induction of AP-1 and Smad signaling in gene reporter assays and repressed endogenous TGF-beta-responsive genes by microarray analyses. DACH1 bound to endogenous NCoR and Smad4 in cultured cells and DACH1 co-localized with NCoR in nuclear dotlike structures. NCoR enhanced DACH1 repression, and the repression of TGF-beta-induced AP-1 or Smad signaling by DACH1 required the DACH1 DS domain. The DS domain of DACH was sufficient for NCoR binding at a Smad4-binding site. Smad4 was required for DACH1 repression of Smad signaling. In Smad4 null HTB-134 cells, DACH1 inhibited the activation of SBE-4 reporter activity induced by Smad2 or Smad3 only in the presence of Smad4. DACH1 participates in the negative regulation of TGF-beta signaling by interacting with NCoR and Smad4.

  2. Deep Sequencing of the Medicago truncatula Root Transcriptome Reveals a Massive and Early Interaction between Nodulation Factor and Ethylene Signals1[OPEN

    PubMed Central

    Larrainzar, Estíbaliz; Riely, Brendan K.; Kim, Sang Cheol; Carrasquilla-Garcia, Noelia; Yu, Hee-Ju; Hwang, Hyun-Ju; Oh, Mijin; Kim, Goon Bo; Surendrarao, Anandkumar K.; Chasman, Deborah; Siahpirani, Alireza F.; Penmetsa, Ramachandra V.; Lee, Gang-Seob; Kim, Namshin; Roy, Sushmita; Mun, Jeong-Hwan; Cook, Douglas R.

    2015-01-01

    The legume-rhizobium symbiosis is initiated through the activation of the Nodulation (Nod) factor-signaling cascade, leading to a rapid reprogramming of host cell developmental pathways. In this work, we combine transcriptome sequencing with molecular genetics and network analysis to quantify and categorize the transcriptional changes occurring in roots of Medicago truncatula from minutes to days after inoculation with Sinorhizobium medicae. To identify the nature of the inductive and regulatory cues, we employed mutants with absent or decreased Nod factor sensitivities (i.e. Nodulation factor perception and Lysine motif domain-containing receptor-like kinase3, respectively) and an ethylene (ET)-insensitive, Nod factor-hypersensitive mutant (sickle). This unique data set encompasses nine time points, allowing observation of the symbiotic regulation of diverse biological processes with high temporal resolution. Among the many outputs of the study is the early Nod factor-induced, ET-regulated expression of ET signaling and biosynthesis genes. Coupled with the observation of massive transcriptional derepression in the ET-insensitive background, these results suggest that Nod factor signaling activates ET production to attenuate its own signal. Promoter:β-glucuronidase fusions report ET biosynthesis both in root hairs responding to rhizobium as well as in meristematic tissue during nodule organogenesis and growth, indicating that ET signaling functions at multiple developmental stages during symbiosis. In addition, we identified thousands of novel candidate genes undergoing Nod factor-dependent, ET-regulated expression. We leveraged the power of this large data set to model Nod factor- and ET-regulated signaling networks using MERLIN, a regulatory network inference algorithm. These analyses predict key nodes regulating the biological process impacted by Nod factor perception. We have made these results available to the research community through a searchable online

  3. Tyrosine Phosphorylation of the Pioneer Transcription Factor FoxA1 Promotes Activation of Estrogen Signaling.

    PubMed

    Yamaguchi, Noritaka; Shibazaki, Misato; Yamada, Chiaki; Anzai, Erina; Morii, Mariko; Nakayama, Yuji; Kuga, Takahisa; Hashimoto, Yuuki; Tomonaga, Takeshi; Yamaguchi, Naoto

    2017-06-01

    The pioneer transcription factor FoxA1 plays an important role in estrogen signaling by opening closed chromatin and promoting recruitment of the estrogen receptor to its target regions in DNA. In this study, we analyzed tyrosine phosphorylation of FoxA1 by the non-receptor-type tyrosine kinase c-Abl. c-Abl was shown to phosphorylate FoxA1 at multiple sites, especially in the N- and C-terminal regions. Tyr429 and Tyr464 were identified as the major phosphorylation sites in the FoxA1 C-terminal region. The phosphomimetic and nonphosphorylatable FoxA1 mutants were generated by glutamic acid and phenylalanine substitutions at these tyrosine residues, respectively. The phosphomimetic FoxA1 promoted the activation of estrogen signaling, whereas the nonphosphorylatable FoxA1 suppressed its activation. Stimulation with the epidermal growth factor, which activates c-Abl, enhanced the activation of estrogen signaling. In contrast, the c-Abl inhibitor imatinib reduced its activation. The phosphomimetic FoxA1 mutant showed a higher affinity toward histone H3 than the wild-type. These results suggest that c-Abl-mediated phosphorylation of FoxA1 promotes the activation of estrogen signaling by inducing its binding to histones. J. Cell. Biochem. 118: 1453-1461, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  4. The Acetylase/Deacetylase Couple CREB-binding Protein/Sirtuin 1 Controls Hypoxia-inducible Factor 2 Signaling*

    PubMed Central

    Chen, Rui; Xu, Min; Hogg, Richard T.; Li, Jiwen; Little, Bertis; Gerard, Robert D.; Garcia, Joseph A.

    2012-01-01

    Hypoxia-inducible factors (HIFs) are oxygen-sensitive transcription factors. HIF-1α plays a prominent role in hypoxic gene induction. HIF-2α target genes are more restricted but include erythropoietin (Epo), one of the most highly hypoxia-inducible genes in mammals. We previously reported that HIF-2α is acetylated during hypoxia but is rapidly deacetylated by the stress-responsive deacetylase Sirtuin 1. We now demonstrate that the lysine acetyltransferases cAMP-response element-binding protein-binding protein (CBP) and p300 are required for efficient Epo induction during hypoxia. However, despite close structural similarity, the roles of CBP and p300 differ in HIF signaling. CBP acetylates HIF-2α, is a major coactivator for HIF-2-mediated Epo induction, and is required for Sirt1 augmentation of HIF-2 signaling during hypoxia in Hep3B cells. In comparison, p300 is a major contributor for HIF-1 signaling as indicated by induction of Pgk1. Whereas CBP can bind with HIF-2α independent of the HIF-2α C-terminal activation domain via enzyme/substrate interactions, p300 only complexes with HIF-2α through the C-terminal activation domain. Maximal CBP/HIF-2 signaling requires intact CBP acetyltransferase activity in both Hep3B cells as well as in mice. PMID:22807441

  5. The BTB-zinc Finger Transcription Factor Abrupt Acts as an Epithelial Oncogene in Drosophila melanogaster through Maintaining a Progenitor-like Cell State

    PubMed Central

    Turkel, Nezaket; Sahota, Virender K.; Bolden, Jessica E.; Goulding, Karen R.; Doggett, Karen; Willoughby, Lee F.; Blanco, Enrique; Martin-Blanco, Enrique; Corominas, Montserrat; Ellul, Jason; Aigaki, Toshiro; Richardson, Helena E.; Brumby, Anthony M.

    2013-01-01

    The capacity of tumour cells to maintain continual overgrowth potential has been linked to the commandeering of normal self-renewal pathways. Using an epithelial cancer model in Drosophila melanogaster, we carried out an overexpression screen for oncogenes capable of cooperating with the loss of the epithelial apico-basal cell polarity regulator, scribbled (scrib), and identified the cell fate regulator, Abrupt, a BTB-zinc finger protein. Abrupt overexpression alone is insufficient to transform cells, but in cooperation with scrib loss of function, Abrupt promotes the formation of massive tumours in the eye/antennal disc. The steroid hormone receptor coactivator, Taiman (a homologue of SRC3/AIB1), is known to associate with Abrupt, and Taiman overexpression also drives tumour formation in cooperation with the loss of Scrib. Expression arrays and ChIP-Seq indicates that Abrupt overexpression represses a large number of genes, including steroid hormone-response genes and multiple cell fate regulators, thereby maintaining cells within an epithelial progenitor-like state. The progenitor-like state is characterised by the failure to express the conserved Eyes absent/Dachshund regulatory complex in the eye disc, and in the antennal disc by the failure to express cell fate regulators that define the temporal elaboration of the appendage along the proximo-distal axis downstream of Distalless. Loss of scrib promotes cooperation with Abrupt through impaired Hippo signalling, which is required and sufficient for cooperative overgrowth with Abrupt, and JNK (Jun kinase) signalling, which is required for tumour cell migration/invasion but not overgrowth. These results thus identify a novel cooperating oncogene, identify mammalian family members of which are also known oncogenes, and demonstrate that epithelial tumours in Drosophila can be characterised by the maintenance of a progenitor-like state. PMID:23874226

  6. Learning and signal copying facilitate communication among bird species

    PubMed Central

    Wheatcroft, David; Price, Trevor D.

    2013-01-01

    Signals relevant to different sets of receivers in different contexts create a conflict for signal design. A classic example is vocal alarm signals, often used both during intraspecific and interspecific interactions. How can signals alert individuals from a variety of other species in some contexts, while also maintaining efficient communication among conspecifics? We studied heterospecific responses to avian alarm signals that drive the formation of anti-predator groups but are also used during intraspecific interactions. In three species-rich communities in the western Himalayas, alarm signals vary drastically across species. We show that, independently of differences in their calls, birds respond strongly to the alarm signals of other species with which they co-occur and much more weakly to those of species with which they do not co-occur. These results suggest that previous exposure and learning maintain heterospecific responses in the face of widespread signal divergence. At an area where only two species regularly interact, one species' calls incorporate the call of the other. We demonstrate experimentally that signal copying allows strong responses even without previous exposure and suggest that such hybrid calls may be especially favoured when pairwise interactions between species are strong. PMID:23446529

  7. Brain-Derived Neurotrophic Factor Signaling Rewrites the Glucocorticoid Transcriptome via Glucocorticoid Receptor Phosphorylation

    PubMed Central

    Lambert, W. Marcus; Xu, Chong-Feng; Neubert, Thomas A.; Chao, Moses V.

    2013-01-01

    Abnormal glucocorticoid and neurotrophin signaling has been implicated in numerous psychiatric disorders. However, the impact of neurotrophic signaling on glucocorticoid receptor (GR)-dependent gene expression is not understood. We therefore examined the impact of brain-derived neurotrophic factor (BDNF) signaling on GR transcriptional regulatory function by gene expression profiling in primary rat cortical neurons stimulated with the selective GR agonist dexamethasone (Dex) and BDNF, alone or in combination. Simultaneous treatment with BDNF and Dex elicited a unique set of GR-responsive genes associated with neuronal growth and differentiation and also enhanced the induction of a large number of Dex-sensitive genes. BDNF via its receptor TrkB enhanced the transcriptional activity of a synthetic GR reporter, suggesting a direct effect of BDNF signaling on GR function. Indeed, BDNF treatment induces the phosphorylation of GR at serine 155 (S155) and serine 287 (S287). Expression of a nonphosphorylatable mutant (GR S155A/S287A) impaired the induction of a subset of BDNF- and Dex-regulated genes. Mechanistically, BDNF-induced GR phosphorylation increased GR occupancy and cofactor recruitment at the promoter of a BDNF-enhanced gene. GR phosphorylation in vivo is sensitive to changes in the levels of BDNF and TrkB as well as stress. Therefore, BDNF signaling specifies and amplifies the GR transcriptome through a coordinated GR phosphorylation-dependent detection mechanism. PMID:23878391

  8. Bid Promotes K63-Linked Polyubiquitination of Tumor Necrosis Factor Receptor Associated Factor 6 (TRAF6) and Sensitizes to Mutant SOD1-Induced Proinflammatory Signaling in Microglia.

    PubMed

    Kinsella, Sinéad; König, Hans-Georg; Prehn, Jochen H M

    2016-01-01

    Mutations in the superoxide dismutase 1 (SOD1) gene contribute to motoneuron degeneration and are evident in 20% of familial amyotrophic lateral sclerosis cases. Mutant SOD1 induces microglial activation through a stimulation of Toll-like receptors 2 and 4 (TLR2 and TLR4). In the present study, we identified the proapoptotic Bcl-2 family protein Bid as a positive regulator of mutant SOD1-induced TLR-nuclear factor-κB (NF-κB) signaling in microglia. bid-deficient primary mouse microglia showed reduced NF-κB signaling in response to TLR4 activation or exposure to conditioned medium derived from SOD1 (G93A) expressing NSC-34 cells. Attenuation of NF-κB signaling in bid-deficient microglia was associated with lower levels of phosphorylated IKKα/β and p65, with a delayed degradation of IκBα and enhanced degradation of Peli1. Upstream of IKK, we found that Bid interacted with, and promoted, the K63-linked polyubiquitination of the E3 ubiquitin ligase tumor necrosis factor receptor associated factor 6 (TRAF6) in microglia. Our study suggests a key role for Bid in the regulation of TLR4-NF-κB proinflammatory signaling during mutant SOD1-induced disease pathology. Bid promotes TLR4-NF-κB signaling by interacting with TRAF6 and promoting TRAF6 K63-linked polyubiquitination in microglia.

  9. Inhibition of platelet-derived growth factor signaling prevents muscle fiber growth during skeletal muscle hypertrophy.

    PubMed

    Sugg, Kristoffer B; Korn, Michael A; Sarver, Dylan C; Markworth, James F; Mendias, Christopher L

    2017-03-01

    The platelet-derived growth factor receptors alpha and beta (PDGFRα and PDGFRβ) mark fibroadipogenic progenitor cells/fibroblasts and pericytes in skeletal muscle, respectively. While the role that these cells play in muscle growth and development has been evaluated, it was not known whether the PDGF receptors activate signaling pathways that control transcriptional and functional changes during skeletal muscle hypertrophy. To evaluate this, we inhibited PDGFR signaling in mice subjected to a synergist ablation muscle growth procedure, and performed analyses 3 and 10 days after induction of hypertrophy. The results from this study indicate that PDGF signaling is required for fiber hypertrophy, extracellular matrix production, and angiogenesis that occur during muscle growth. © 2017 Federation of European Biochemical Societies.

  10. Careless talk costs lives: fibroblast growth factor receptor signalling and the consequences of pathway malfunction.

    PubMed

    Carter, Edward P; Fearon, Abbie E; Grose, Richard P

    2015-04-01

    Since its discovery 40 years ago, fibroblast growth factor (FGF) receptor (FGFR) signalling has been found to regulate fundamental cellular behaviours in a wide range of cell types. FGFRs regulate development, homeostasis, and repair and are implicated in many disorders and diseases; and indeed, there is extensive potential for severe consequences, be they developmental, homeostatic, or oncogenic, should FGF-FGFR signalling go awry, so careful control of the pathway is critically important. In this review, we discuss the recent developments in the FGF field, highlighting how FGFR signalling works in normal cells, how it can go wrong, how frequently it is compromised, and how it is being targeted therapeutically. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Endothelial C-type natriuretic peptide maintains vascular homeostasis

    PubMed Central

    Moyes, Amie J.; Khambata, Rayomand S.; Villar, Inmaculada; Bubb, Kristen J.; Baliga, Reshma S.; Lumsden, Natalie G.; Xiao, Fang; Gane, Paul J.; Rebstock, Anne-Sophie; Worthington, Roberta J.; Simone, Michela I.; Mota, Filipa; Rivilla, Fernando; Vallejo, Susana; Peiró, Concepción; Sánchez Ferrer, Carlos F.; Djordjevic, Snezana; Caulfield, Mark J.; MacAllister, Raymond J.; Selwood, David L.; Ahluwalia, Amrita; Hobbs, Adrian J.

    2014-01-01

    The endothelium plays a fundamental role in maintaining vascular homeostasis by releasing factors that regulate local blood flow, systemic blood pressure, and the reactivity of leukocytes and platelets. Accordingly, endothelial dysfunction underpins many cardiovascular diseases, including hypertension, myocardial infarction, and stroke. Herein, we evaluated mice with endothelial-specific deletion of Nppc, which encodes C-type natriuretic peptide (CNP), and determined that this mediator is essential for multiple aspects of vascular regulation. Specifically, disruption of CNP leads to endothelial dysfunction, hypertension, atherogenesis, and aneurysm. Moreover, we identified natriuretic peptide receptor–C (NPR-C) as the cognate receptor that primarily underlies CNP-dependent vasoprotective functions and developed small-molecule NPR-C agonists to target this pathway. Administration of NPR-C agonists promotes a vasorelaxation of isolated resistance arteries and a reduction in blood pressure in wild-type animals that is diminished in mice lacking NPR-C. This work provides a mechanistic explanation for genome-wide association studies that have linked the NPR-C (Npr3) locus with hypertension by demonstrating the importance of CNP/NPR-C signaling in preserving vascular homoeostasis. Furthermore, these results suggest that the CNP/NPR-C pathway has potential as a disease-modifying therapeutic target for cardiovascular disorders. PMID:25105365

  12. Basic aspects of tumor cell fatty acid-regulated signaling and transcription factors.

    PubMed

    Comba, Andrea; Lin, Yi-Hui; Eynard, Aldo Renato; Valentich, Mirta Ana; Fernandez-Zapico, Martín Ernesto; Pasqualini, Marìa Eugenia

    2011-12-01

    This article reviews the current knowledge and experimental research about the mechanisms by which fatty acids and their derivatives control specific gene expression involved during carcinogenesis. Changes in dietary fatty acids, specifically the polyunsaturated fatty acids of the ω-3 and ω-6 families and some derived eicosanoids from lipoxygenases, cyclooxygenases, and cytochrome P-450, seem to control the activity of transcription factor families involved in cancer cell proliferation or cell death. Their regulation may be carried out either through direct binding to DNA as peroxisome proliferator-activated receptors or via modulation in an indirect manner of signaling pathway molecules (e.g., protein kinase C) and other transcription factors (nuclear factor kappa B and sterol regulatory element binding protein). Knowledge of the mechanisms by which fatty acids control specific gene expression may identify important risk factors for cancer and provide insight into the development of new therapeutic strategies for a better management of whole body lipid metabolism.

  13. Cellular Signaling by Fibroblast Growth Factors (FGFs) and Their Receptors (FGFRs) in Male Reproduction

    PubMed Central

    Cotton, Leanne M.; O’Bryan, Moira K.; Hinton, Barry T.

    2008-01-01

    The major function of the reproductive system is to ensure the survival of the species by passing on hereditary traits from one generation to the next. This is accomplished through the production of gametes and the generation of hormones that function in the maturation and regulation of the reproductive system. It is well established that normal development and function of the male reproductive system is mediated by endocrine and paracrine signaling pathways. Fibroblast growth factors (FGFs), their receptors (FGFRs), and signaling cascades have been implicated in a diverse range of cellular processes including: proliferation, apoptosis, cell survival, chemotaxis, cell adhesion, motility, and differentiation. The maintenance and regulation of correct FGF signaling is evident from human and mouse genetic studies which demonstrate that mutations leading to disruption of FGF signaling cause a variety of developmental disorders including dominant skeletal diseases, infertility, and cancer. Over the course of this review, we will provide evidence for differential expression of FGFs/FGFRs in the testis, male germ cells, the epididymis, the seminal vesicle, and the prostate. We will show that this signaling cascade has an important role in sperm development and maturation. Furthermore, we will demonstrate that FGF/FGFR signaling is essential for normal epididymal function and prostate development. To this end, we will provide evidence for the involvement of the FGF signaling system in the regulation and maintenance of the male reproductive system. PMID:18216218

  14. Lysophosphatidic acid signaling through its receptor initiates profibrotic epithelial cell fibroblast communication mediated by epithelial cell derived connective tissue growth factor.

    PubMed

    Sakai, Norihiko; Chun, Jerold; Duffield, Jeremy S; Lagares, David; Wada, Takashi; Luster, Andrew D; Tager, Andrew M

    2017-03-01

    The expansion of the fibroblast pool is a critical step in organ fibrosis, but the mechanisms driving expansion remain to be fully clarified. We previously showed that lysophosphatidic acid (LPA) signaling through its receptor LPA 1 expressed on fibroblasts directly induces the recruitment of these cells. Here we tested whether LPA-LPA 1 signaling drives fibroblast proliferation and activation during the development of renal fibrosis. LPA 1 -deficient (LPA 1 -/- ) or -sufficient (LPA 1 +/+ ) mice were crossed to mice with green fluorescent protein expression (GFP) driven by the type I procollagen promoter (Col-GFP) to identify fibroblasts. Unilateral ureteral obstruction-induced increases in renal collagen were significantly, though not completely, attenuated in LPA 1 -/- Col-GFP mice, as were the accumulations of both fibroblasts and myofibroblasts. Connective tissue growth factor was detected mainly in tubular epithelial cells, and its levels were suppressed in LPA 1 -/- Col-GFP mice. LPA-LPA 1 signaling directly induced connective tissue growth factor expression in primary proximal tubular epithelial cells, through a myocardin-related transcription factor-serum response factor pathway. Proximal tubular epithelial cell-derived connective tissue growth factor mediated renal fibroblast proliferation and myofibroblast differentiation. Administration of an inhibitor of myocardin-related transcription factor/serum response factor suppressed obstruction-induced renal fibrosis. Thus, targeting LPA-LPA 1 signaling and/or myocardin-related transcription factor/serum response factor-induced transcription could be promising therapeutic strategies for renal fibrosis. Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  15. L-ascorbic acid 2-phosphate and fibroblast growth factor-2 treatment maintains differentiation potential in bone marrow-derived mesenchymal stem cells through expression of hepatocyte growth factor.

    PubMed

    Bae, Sung Hae; Ryu, Hoon; Rhee, Ki-Jong; Oh, Ji-Eun; Baik, Soon Koo; Shim, Kwang Yong; Kong, Jee Hyun; Hyun, Shin Young; Pack, Hyun Sung; Im, Changjo; Shin, Ha Cheol; Kim, Yong Man; Kim, Hyun Soo; Eom, Young Woo; Lee, Jong In

    2015-04-01

    l-ascorbic acid 2-phosphate (Asc-2P) acts as an antioxidant and a stimulator of hepatocyte growth factor (HGF) production. Previously, we reported that depletion of growth factors such as fibroblast growth factor (FGF)-2, epidermal growth factor (EGF), FGF-4 and HGF during serial passage could induce autophagy, senescence and down-regulation of stemness (proliferation via FGF-2/-4 and differentiation via HGF). In this study, we investigated the proliferation and differentiation potential of BMSCs by FGF-2 and Asc-2P. Co-treatment with FGF-2 and Asc-2P induced optimal proliferation of BMSCs and increased the accumulation rate of BMSC numbers during a 2-month culture period. Moreover, differentiation potential was maintained by co-treatment with FGF-2 and Asc-2P via HGF expression. Adipogenic differentiation potential by FGF-2 and Asc-2P was dramatically suppressed by c-Met inhibitors (SU11274). These data suggest that co-treatment with FGF-2 and Asc-2P would be beneficial in obtaining BMSCs that possess "stemness" during long-term culture.

  16. Epithelial-stromal interaction via Notch signaling is essential for the full maturation of gut-associated lymphoid tissues.

    PubMed

    Obata, Yuuki; Kimura, Shunsuke; Nakato, Gaku; Iizuka, Keito; Miyagawa, Yurika; Nakamura, Yutaka; Furusawa, Yukihiro; Sugiyama, Machiko; Suzuki, Keiichiro; Ebisawa, Masashi; Fujimura, Yumiko; Yoshida, Hisahiro; Iwanaga, Toshihiko; Hase, Koji; Ohno, Hiroshi

    2014-12-01

    Intrinsic Notch signaling in intestinal epithelial cells restricts secretory cell differentiation. In gut-associated lymphoid tissue (GALT), stromal cells located beneath the follicle-associated epithelium (FAE) abundantly express the Notch ligand delta-like 1 (Dll1). Here, we show that mice lacking Rbpj-a gene encoding a transcription factor implicated in Notch signaling-in intestinal epithelial cells have defective GALT maturation. This defect can be attributed to the expansion of goblet cells, which leads to the down-regulation of CCL20 in FAE. These data demonstrate that epithelial Notch signaling maintained by stromal cells contributes to the full maturation of GALT by restricting secretory cell differentiation in FAE. © 2014 The Authors.

  17. Angiopoietin–Tie signalling in the cardiovascular and lymphatic systems

    PubMed Central

    Eklund, Lauri; Kangas, Jaakko; Saharinen, Pipsa

    2016-01-01

    Endothelial cells that form the inner layer of blood and lymphatic vessels are important regulators of vascular functions and centrally involved in the pathogenesis of vascular diseases. In addition to the vascular endothelial growth factor (VEGF) receptor pathway, the angiopoietin (Ang)–Tie system is a second endothelial cell specific ligand–receptor signalling system necessary for embryonic cardiovascular and lymphatic development. The Ang–Tie system also regulates postnatal angiogenesis, vessel remodelling, vascular permeability and inflammation to maintain vascular homoeostasis in adult physiology. This system is implicated in numerous diseases where the vasculature has an important contribution, such as cancer, sepsis, diabetes, atherosclerosis and ocular diseases. Furthermore, mutations in the TIE2 signalling pathway cause defects in vascular morphogenesis, resulting in venous malformations and primary congenital glaucoma. Here, we review recent advances in the understanding of the Ang–Tie signalling system, including cross-talk with the vascular endothelial protein tyrosine phosphatase (VE-PTP) and the integrin cell adhesion receptors, focusing on the Ang–Tie system in vascular development and pathogenesis of vascular diseases. PMID:27941161

  18. Exogenous oxidants activate nuclear factor kappa B through Toll-like receptor 4 stimulation to maintain inflammatory phenotype in macrophage.

    PubMed

    Zhang, Yan; Igwe, Orisa J

    2018-01-01

    Disturbances in redox equilibrium in tissue can lead to inflammatory state, which is a mediatory factor in many human diseases. The mechanism(s) by which exogenous oxidants may activate an inflammatory response is not fully understood. Emerging evidence suggests that oxidant-induced Toll-like receptor 4 (TLR4) activation plays a major role in "sterile" inflammation. In the present study, we used murine macrophage RAW-Blue cells, which are chromosomally integrated with secreted embryonic alkaline phosphatase (SEAP) inducible by NF-κB. We confirmed the expression of TLR4 mRNA and protein in RAW-Blue cells by RT-PCR and Western blot, respectively. We showed that oxidants increased intracellular reactive oxygen species production and lipid peroxidation, which resulted in decreased intracellular total antioxidant capacity. Consistent with the actions of TLR4-specific agonist LPS-EK, exogenous oxidants increased transcriptional activity of NF-κB p65 with subsequent release of NF-κB reporter gene SEAP. These effects were blocked by pretreatment with TLR4 neutralizing pAb and TLR4 signaling inhibitor CLI-095. In addition, oxidants decreased the expression of IκBα with enhanced phosphorylation at the Tyr42 residue. Finally, oxidants and LPS-EK increased TNFα production, but did not affect IL-10 production, which may cause imbalance between pro- and anti-inflammatory processes, which CLI-095 inhibited. For biological relevance, we confirmed that oxidants increased release of TNFα and IL-6 in primary macrophages derived from TLR4-WT and TLR4-KO mice. Our results support the involvement of TLR4 mediated oxidant-induced inflammatory phenotype through NF-κB activation in macrophages. Thus exogenous oxidants may play a role in activating inflammatory phenotypes that propagate and maintain chronic disease states. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Regulation of Cellular Communication by Signaling Microdomains in the Blood Vessel Wall

    PubMed Central

    Billaud, Marie; Lohman, Alexander W.; Johnstone, Scott R.; Biwer, Lauren A.; Mutchler, Stephanie; Isakson, Brant E.

    2014-01-01

    It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function. PMID:24671377

  20. Regulation of cellular communication by signaling microdomains in the blood vessel wall.

    PubMed

    Billaud, Marie; Lohman, Alexander W; Johnstone, Scott R; Biwer, Lauren A; Mutchler, Stephanie; Isakson, Brant E

    2014-01-01

    It has become increasingly clear that the accumulation of proteins in specific regions of the plasma membrane can facilitate cellular communication. These regions, termed signaling microdomains, are found throughout the blood vessel wall where cellular communication, both within and between cell types, must be tightly regulated to maintain proper vascular function. We will define a cellular signaling microdomain and apply this definition to the plethora of means by which cellular communication has been hypothesized to occur in the blood vessel wall. To that end, we make a case for three broad areas of cellular communication where signaling microdomains could play an important role: 1) paracrine release of free radicals and gaseous molecules such as nitric oxide and reactive oxygen species; 2) role of ion channels including gap junctions and potassium channels, especially those associated with the endothelium-derived hyperpolarization mediated signaling, and lastly, 3) mechanism of exocytosis that has considerable oversight by signaling microdomains, especially those associated with the release of von Willebrand factor. When summed, we believe that it is clear that the organization and regulation of signaling microdomains is an essential component to vessel wall function.

  1. Essential roles of Gab1 tyrosine phosphorylation in growth factor-mediated signaling and angiogenesis.

    PubMed

    Wang, Weiye; Xu, Suowen; Yin, Meimei; Jin, Zheng Gen

    2015-02-15

    Growth factors and their downstream receptor tyrosine kinases (RTKs) mediate a number of biological processes controlling cell function. Adaptor (docking) proteins, which consist exclusively of domains and motifs that mediate molecular interactions, link receptor activation to downstream effectors. Recent studies have revealed that Grb2-associated-binders (Gab) family members (including Gab1, Gab2, and Gab3), when phosphorylated on tyrosine residues, provide binding sites for multiple effector proteins, such as Src homology-2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2) and phosphatidylinositol 3-kinase (PI3K) regulatory subunit p85, thereby playing important roles in transducing RTKs-mediated signals into pathways with diversified biological functions. Here, we provide an up-to-date overview on the domain structure and biological functions of Gab1, the most intensively studied Gab family protein, in growth factor signaling and biological functions, with a special focus on angiogenesis. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  2. Analysis of corkscrew signaling in the Drosophila epidermal growth factor receptor pathway during myogenesis.

    PubMed

    Johnson Hamlet, M R; Perkins, L A

    2001-11-01

    The Drosophila nonreceptor protein tyrosine phosphatase, Corkscrew (Csw), functions positively in multiple receptor tyrosine kinase (RTK) pathways, including signaling by the epidermal growth factor receptor (EGFR). Detailed phenotypic analyses of csw mutations have revealed that Csw activity is required in many of the same developmental processes that require EGFR function. However, it is still unclear where in the signaling hierarchy Csw functions relative to other proteins whose activities are also required downstream of the receptor. To address this issue, genetic interaction experiments were performed to place csw gene activity relative to the EGFR, spitz (spi), rhomboid (rho), daughter of sevenless (DOS), kinase-suppressor of ras (ksr), ras1, D-raf, pointed (pnt), and moleskin. We followed the EGFR-dependent formation of VA2 muscle precursor cells as a sensitive assay for these genetic interaction studies. First, we established that Csw has a positive function during mesoderm development. Second, we found that tissue-specific expression of a gain-of-function csw construct rescues loss-of-function mutations in other positive signaling genes upstream of rolled (rl)/MAPK in the EGFR pathway. Third, we were able to infer levels of EGFR signaling in various mutant backgrounds during myogenesis. This work extends previous studies of Csw during Torso and Sevenless RTK signaling to include an in-depth analysis of the role of Csw in the EGFR signaling pathway.

  3. Analysis of corkscrew signaling in the Drosophila epidermal growth factor receptor pathway during myogenesis.

    PubMed Central

    Johnson Hamlet, M R; Perkins, L A

    2001-01-01

    The Drosophila nonreceptor protein tyrosine phosphatase, Corkscrew (Csw), functions positively in multiple receptor tyrosine kinase (RTK) pathways, including signaling by the epidermal growth factor receptor (EGFR). Detailed phenotypic analyses of csw mutations have revealed that Csw activity is required in many of the same developmental processes that require EGFR function. However, it is still unclear where in the signaling hierarchy Csw functions relative to other proteins whose activities are also required downstream of the receptor. To address this issue, genetic interaction experiments were performed to place csw gene activity relative to the EGFR, spitz (spi), rhomboid (rho), daughter of sevenless (DOS), kinase-suppressor of ras (ksr), ras1, D-raf, pointed (pnt), and moleskin. We followed the EGFR-dependent formation of VA2 muscle precursor cells as a sensitive assay for these genetic interaction studies. First, we established that Csw has a positive function during mesoderm development. Second, we found that tissue-specific expression of a gain-of-function csw construct rescues loss-of-function mutations in other positive signaling genes upstream of rolled (rl)/MAPK in the EGFR pathway. Third, we were able to infer levels of EGFR signaling in various mutant backgrounds during myogenesis. This work extends previous studies of Csw during Torso and Sevenless RTK signaling to include an in-depth analysis of the role of Csw in the EGFR signaling pathway. PMID:11729154

  4. Transcription factor TLX1 controls retinoic acid signaling to ensure spleen development

    PubMed Central

    Lenti, Elisa; Farinello, Diego; Penkov, Dmitry; Castagnaro, Laura; Lavorgna, Giovanni; Wuputra, Kenly; Tjaden, Naomi E. Butler; Bernassola, Francesca; Caridi, Nicoletta; Wagner, Michael; Kozinc, Katja; Niederreither, Karen; Blasi, Francesco; Pasini, Diego; Trainor, Paul A.

    2016-01-01

    The molecular mechanisms that underlie spleen development and congenital asplenia, a condition linked to increased risk of overwhelming infections, remain largely unknown. The transcription factor TLX1 controls cell fate specification and organ expansion during spleen development, and Tlx1 deletion causes asplenia in mice. Deregulation of TLX1 expression has recently been proposed in the pathogenesis of congenital asplenia in patients carrying mutations of the gene-encoding transcription factor SF-1. Herein, we have shown that TLX1-dependent regulation of retinoic acid (RA) metabolism is critical for spleen organogenesis. In a murine model, loss of Tlx1 during formation of the splenic anlage increased RA signaling by regulating several genes involved in RA metabolism. Uncontrolled RA activity resulted in premature differentiation of mesenchymal cells and reduced vasculogenesis of the splenic primordium. Pharmacological inhibition of RA signaling in Tlx1-deficient animals partially rescued the spleen defect. Finally, spleen growth was impaired in mice lacking either cytochrome P450 26B1 (Cyp26b1), which results in excess RA, or retinol dehydrogenase 10 (Rdh10), which results in RA deficiency. Together, these findings establish TLX1 as a critical regulator of RA metabolism and provide mechanistic insights into the molecular determinants of human congenital asplenia. PMID:27214556

  5. Comparative transcriptomics and proteomics analysis of citrus fruit, to improve understanding of the effect of low temperature on maintaining fruit quality during lengthy post-harvest storage

    PubMed Central

    Yun, Ze; Jin, Shuai; Ding, Yuduan; Wang, Zhuang; Gao, Huijun; Pan, Zhiyong; Xu, Juan; Cheng, Yunjiang; Deng, Xiuxin

    2012-01-01

    Fruit quality is a very complex trait that is affected by both genetic and non-genetic factors. Generally, low temperature (LT) is used to delay fruit senescence and maintain fruit quality during post-harvest storage but the molecular mechanisms involved are poorly understood. Hirado Buntan Pummelo (HBP; Citrus grandis × C. paradis) fruit were chosen to explore the mechanisms that maintain citrus fruit quality during lengthy LT storage using transcriptome and proteome studies based on digital gene expression (DGE) profiling and two-dimensional gel electrophoresis (2-DE), respectively. Results showed that LT up-regulated stress-responsive genes, arrested signal transduction, and inhibited primary metabolism, secondary metabolism and the transportation of metabolites. Calcineurin B-like protein (CBL)–CBL-interacting protein kinase complexes might be involved in the signal transduction of LT stress, and fruit quality is likely to be regulated by sugar-mediated auxin and abscisic acid (ABA) signalling. Furthermore, ABA was specific to the regulation of citrus fruit senescence and was not involved in the LT stress response. In addition, the accumulation of limonin, nomilin, methanol, and aldehyde, together with the up-regulated heat shock proteins, COR15, and cold response-related genes, provided a comprehensive proteomics and transcriptomics view on the coordination of fruit LT stress responses. PMID:22323274

  6. Polymorphism at a mimicry supergene maintained by opposing frequency-dependent selection pressures.

    PubMed

    Chouteau, Mathieu; Llaurens, Violaine; Piron-Prunier, Florence; Joron, Mathieu

    2017-08-01

    Explaining the maintenance of adaptive diversity within populations is a long-standing goal in evolutionary biology, with important implications for conservation, medicine, and agriculture. Adaptation often leads to the fixation of beneficial alleles, and therefore it erodes local diversity so that understanding the coexistence of multiple adaptive phenotypes requires deciphering the ecological mechanisms that determine their respective benefits. Here, we show how antagonistic frequency-dependent selection (FDS), generated by natural and sexual selection acting on the same trait, maintains mimicry polymorphism in the toxic butterfly Heliconius numata Positive FDS imposed by predators on mimetic signals favors the fixation of the most abundant and best-protected wing-pattern morph, thereby limiting polymorphism. However, by using mate-choice experiments, we reveal disassortative mate preferences of the different wing-pattern morphs. The resulting negative FDS on wing-pattern alleles is consistent with the excess of heterozygote genotypes at the supergene locus controlling wing-pattern variation in natural populations of H. numata The combined effect of positive and negative FDS on visual signals is sufficient to maintain a diversity of morphs displaying accurate mimicry with other local prey, although some of the forms only provide moderate protection against predators. Our findings help understand how alternative adaptive phenotypes can be maintained within populations and emphasize the need to investigate interactions between selective pressures in other cases of puzzling adaptive polymorphism.

  7. Polymorphism at a mimicry supergene maintained by opposing frequency-dependent selection pressures

    PubMed Central

    Chouteau, Mathieu; Llaurens, Violaine; Piron-Prunier, Florence; Joron, Mathieu

    2017-01-01

    Explaining the maintenance of adaptive diversity within populations is a long-standing goal in evolutionary biology, with important implications for conservation, medicine, and agriculture. Adaptation often leads to the fixation of beneficial alleles, and therefore it erodes local diversity so that understanding the coexistence of multiple adaptive phenotypes requires deciphering the ecological mechanisms that determine their respective benefits. Here, we show how antagonistic frequency-dependent selection (FDS), generated by natural and sexual selection acting on the same trait, maintains mimicry polymorphism in the toxic butterfly Heliconius numata. Positive FDS imposed by predators on mimetic signals favors the fixation of the most abundant and best-protected wing-pattern morph, thereby limiting polymorphism. However, by using mate-choice experiments, we reveal disassortative mate preferences of the different wing-pattern morphs. The resulting negative FDS on wing-pattern alleles is consistent with the excess of heterozygote genotypes at the supergene locus controlling wing-pattern variation in natural populations of H. numata. The combined effect of positive and negative FDS on visual signals is sufficient to maintain a diversity of morphs displaying accurate mimicry with other local prey, although some of the forms only provide moderate protection against predators. Our findings help understand how alternative adaptive phenotypes can be maintained within populations and emphasize the need to investigate interactions between selective pressures in other cases of puzzling adaptive polymorphism. PMID:28673971

  8. Optimization of human granulocyte macrophage-colony stimulating factor (hGM-CSF) expression using asparaginase and xylanase gene's signal sequences in Escherichia coli.

    PubMed

    Khasa, Yogender Pal; Khushoo, Amardeep; Tapryal, Suman; Mukherjee, K J

    2011-09-01

    The toxicity of the recombinant protein towards the expression host remains a significant deterrent for bioprocess development. In this study, the expression of human granulocyte macrophage-colony stimulating factor (hGM-CSF), which is known to be toxic to its host, was enhanced many folds using a combination of genetic and bioprocess strategies in Escherichia coli. The N terminus attachment of endoxylanase and asparaginase signal sequences from Bacillus subtilis and E. coli, respectively, in combination with and without His-tag, considerably improved expression levels. Induction and media optimization studies in shake flask cultures resulted in a maximal hGM-CSF concentration of 365 mg/L in the form of inclusion bodies (IBs) with a specific product yield (Y (P/X)) of 120 mg/g dry cell weight in case of the asparaginase signal. Culturing the cells in nutrient rich Terrific broth maintained the specific product yields (Y (P/X)) while a 6.6-fold higher volumetric concentration of both product and biomass was obtained. The purification and refolding steps were optimized resulting in a 95% pure protein with a fairly high refolding yield of 45%. The biological activity of the refolded protein was confirmed by a cell proliferation assay on hGM-CSF dependent human erythroleukemia TF-1 cells. This study demonstrated that this indeed is a viable route for the efficient production of hGM-CSF.

  9. Fibroblast growth factor receptor signaling affects development and function of dopamine neurons - inhibition results in a schizophrenia-like syndrome in transgenic mice.

    PubMed

    Klejbor, Ilona; Myers, Jason M; Hausknecht, Kathy; Corso, Thomas D; Gambino, Angelo S; Morys, Janusz; Maher, Pamela A; Hard, Robert; Richards, Jerry; Stachowiak, Ewa K; Stachowiak, Michal K

    2006-06-01

    Developing and mature midbrain dopamine (DA) neurons express fibroblast growth factor (FGF) receptor-1 (FGFR1). To determine the role of FGFR1 signaling in the development of DA neurons, we generated transgenic mice expressing a dominant negative mutant [FGFR1(TK-)] from the catecholaminergic, neuron-specific tyrosine hydroxylase (TH) gene promoter. In homozygous th(tk-)/th(tk-) mice, significant reductions in the size of TH-immunoreactive neurons were found in the substantia nigra compacta (SNc) and the ventral tegmental area (VTA) at postnatal days 0 and 360. Newborn th(tk-)/th(tk-) mice had a reduced density of DA neurons in both SNc and VTA, and the changes in SNc were maintained into adulthood. The reduced density of DA transporter in the striatum further demonstrated an impaired development of the nigro-striatal DA system. Paradoxically, the th(tk-)/th(tk-) mice had increased levels of DA, homovanilic acid and 3-methoxytyramine in the striatum, indicative of excessive DA transmission. These structural and biochemical changes in DA neurons are similar to those reported in human patients with schizophrenia and, furthermore, these th(tk-)/th(tk-) mice displayed an impaired prepulse inhibition that was reversed by a DA receptor antagonist. Thus, this study establishes a new developmental model for a schizophrenia-like disorder in which the inhibition of FGF signaling leads to alterations in DA neurons and DA-mediated behavior.

  10. AMPA receptor-induced local brain-derived neurotrophic factor signaling mediates motor recovery after stroke.

    PubMed

    Clarkson, Andrew N; Overman, Justine J; Zhong, Sheng; Mueller, Rudolf; Lynch, Gary; Carmichael, S Thomas

    2011-03-09

    Stroke is the leading cause of adult disability. Recovery after stroke shares similar molecular and cellular properties with learning and memory. A main component of learning-induced plasticity involves signaling through AMPA receptors (AMPARs). We systematically tested the role of AMPAR function in motor recovery in a mouse model of focal stroke. AMPAR function controls functional recovery beginning 5 d after the stroke. Positive allosteric modulators of AMPARs enhance recovery of limb control when administered after a delay from the stroke. Conversely, AMPAR antagonists impair motor recovery. The contributions of AMPARs to recovery are mediated by release of brain-derived neurotrophic factor (BDNF) in periinfarct cortex, as blocking local BDNF function in periinfarct cortex blocks AMPAR-mediated recovery and prevents the normal pattern of motor recovery. In contrast to a delayed AMPAR role in motor recovery, early administration of AMPAR agonists after stroke increases stroke damage. These findings indicate that the role of glutamate signaling through the AMPAR changes over time in stroke: early potentiation of AMPAR signaling worsens stroke damage, whereas later potentiation of the same signaling system improves functional recovery.

  11. Ultrasound Targeted Microbubble Destruction-Mediated Delivery of a Transcription Factor Decoy Inhibits STAT3 Signaling and Tumor Growth

    PubMed Central

    Kopechek, Jonathan A.; Carson, Andrew R.; McTiernan, Charles F.; Chen, Xucai; Hasjim, Bima; Lavery, Linda; Sen, Malabika; Grandis, Jennifer R.; Villanueva, Flordeliza S.

    2015-01-01

    Signal transducer and activator of transcription 3 (STAT3) is constitutively activated in many cancers where it acts to promote tumor progression. A STAT3-specific transcription factor decoy has been developed to suppress STAT3 downstream signaling, but a delivery strategy is needed to improve clinical translation. Ultrasound-targeted microbubble destruction (UTMD) has been shown to enhance image-guided local delivery of molecular therapeutics to a target site. The objective of this study was to deliver STAT3 decoy to squamous cell carcinoma (SCC) tumors using UTMD to disrupt STAT3 signaling and inhibit tumor growth. Studies performed demonstrated that UTMD treatment with STAT3 decoy-loaded microbubbles inhibited STAT3 signaling in SCC cells in vitro. Studies performed in vivo demonstrated that UTMD treatment with STAT3 decoy-loaded microbubbles induced significant tumor growth inhibition (31-51% reduced tumor volume vs. controls, p < 0.05) in mice bearing SCC tumors. Furthermore, expression of STAT3 downstream target genes (Bcl-xL and cyclin D1) was significantly reduced (34-39%, p < 0.05) in tumors receiving UTMD treatment with STAT3 decoy-loaded microbubbles compared to controls. In addition, the quantity of radiolabeled STAT3 decoy detected in tumors eight hours after treatment was significantly higher with UTMD treatment compared to controls (70-150%, p < 0.05). This study demonstrates that UTMD can increase delivery of a transcription factor decoy to tumors in vivo and that the decoy can inhibit STAT3 signaling and tumor growth. These results suggest that UTMD treatment holds potential for clinical use to increase the concentration of a transcription factor signaling inhibitor in the tumor. PMID:26681983

  12. Chromatin-Remodeling-Factor ARID1B Represses Wnt/β-Catenin Signaling

    PubMed Central

    Vasileiou, Georgia; Ekici, Arif B.; Uebe, Steffen; Zweier, Christiane; Hoyer, Juliane; Engels, Hartmut; Behrens, Jürgen; Reis, André; Hadjihannas, Michel V.

    2015-01-01

    The link of chromatin remodeling to both neurodevelopment and cancer has recently been highlighted by the identification of mutations affecting BAF chromatin-remodeling components, such as ARID1B, in individuals with intellectual disability and cancer. However, the underlying molecular mechanism(s) remains unknown. Here, we show that ARID1B is a repressor of Wnt/β-catenin signaling. Through whole-transcriptome analysis, we find that in individuals with intellectual disability and ARID1B loss-of-function mutations, Wnt/β-catenin target genes are upregulated. Using cellular models of low and high Wnt/β-catenin activity, we demonstrate that knockdown of ARID1B activates Wnt/β-catenin target genes and Wnt/β-catenin-dependent transcriptional reporters in a β-catenin-dependent manner. Reciprocally, forced expression of ARID1B inhibits Wnt/β-catenin signaling downstream of the β-catenin destruction complex. Both endogenous and exogenous ARID1B associate with β-catenin and repress Wnt/β-catenin-mediated transcription through the BAF core subunit BRG1. Accordingly, mutations in ARID1B leading to partial or complete deletion of its BRG1-binding domain, as is often observed in intellectual disability and cancers, compromise association with β-catenin, and the resultant ARID1B mutant proteins fail to suppress Wnt/β-catenin signaling. Finally, knockdown of ARID1B in mouse neuroblastoma cells leads to neurite outgrowth through β-catenin. The data suggest that aberrations in chromatin-remodeling factors, such as ARID1B, might contribute to neurodevelopmental abnormalities and cancer through deregulation of developmental and oncogenic pathways, such as the Wnt/β-catenin signaling pathway. PMID:26340334

  13. Disturbance maintains alternative biome states.

    PubMed

    Dantas, Vinícius de L; Hirota, Marina; Oliveira, Rafael S; Pausas, Juli G

    2016-01-01

    Understanding the mechanisms controlling the distribution of biomes remains a challenge. Although tropical biome distribution has traditionally been explained by climate and soil, contrasting vegetation types often occur as mosaics with sharp boundaries under very similar environmental conditions. While evidence suggests that these biomes are alternative states, empirical broad-scale support to this hypothesis is still lacking. Using community-level field data and a novel resource-niche overlap approach, we show that, for a wide range of environmental conditions, fire feedbacks maintain savannas and forests as alternative biome states in both the Neotropics and the Afrotropics. In addition, wooded grasslands and savannas occurred as alternative grassy states in the Afrotropics, depending on the relative importance of fire and herbivory feedbacks. These results are consistent with landscape scale evidence and suggest that disturbance is a general factor driving and maintaining alternative biome states and vegetation mosaics in the tropics. © 2015 John Wiley & Sons Ltd/CNRS.

  14. Distinguishing autocrine and paracrine signals in hematopoietic stem cell culture using a biofunctional microcavity platform

    NASA Astrophysics Data System (ADS)

    Müller, Eike; Wang, Weijia; Qiao, Wenlian; Bornhäuser, Martin; Zandstra, Peter W.; Werner, Carsten; Pompe, Tilo

    2016-08-01

    Homeostasis of hematopoietic stem cells (HSC) in the mammalian bone marrow stem cell niche is regulated by signals of the local microenvironment. Besides juxtacrine, endocrine and metabolic cues, paracrine and autocrine signals are involved in controlling quiescence, proliferation and differentiation of HSC with strong implications on expansion and differentiation ex vivo as well as in vivo transplantation. Towards this aim, a cell culture analysis on a polymer microcavity carrier platform was combined with a partial least square analysis of a mechanistic model of cell proliferation. We could demonstrate the discrimination of specific autocrine and paracrine signals from soluble factors as stimulating and inhibitory effectors in hematopoietic stem and progenitor cell culture. From that we hypothesize autocrine signals to be predominantly involved in maintaining the quiescent state of HSC in single-cell niches and advocate our analysis platform as an unprecedented option for untangling convoluted signaling mechanisms in complex cell systems being it of juxtacrine, paracrine or autocrine origin.

  15. 0-6775 : NTCIP-based traffic signal evaluation and optimization toolbox.

    DOT National Transportation Integrated Search

    2014-08-01

    Routine maintenance of traffic signals requires : identification and resolution of hardware faults : and operational inefficiencies. Like most : agencies in charge of operating and maintaining : traffic signals scattered over large geographic : regio...

  16. Perceived Benefits and Factors that Influence the Ability to Establish and Maintain Patient Support Groups in Rare Diseases: A Scoping Review.

    PubMed

    Delisle, Vanessa C; Gumuchian, Stephanie T; Rice, Danielle B; Levis, Alexander W; Kloda, Lorie A; Körner, Annett; Thombs, Brett D

    2017-06-01

    Support groups are an important resource for many people living with rare diseases. The perceived benefits of participating in support groups for people with rare diseases and factors that may influence the ability to successfully establish and maintain these groups are not well understood. Thus, the objective of this scoping review was to provide a mapping of the available evidence on the (1) benefits or perceived benefits of participating in rare disease support groups and (2) barriers and facilitators of establishing and maintaining these groups. CINAHL and PubMed were searched from January 2000 to August 2015, with no language restrictions. Publications that described the benefits or perceived benefits of participating in rare disease support groups or the barriers and facilitators of establishing and maintaining them were eligible for inclusion. Two investigators independently evaluated titles/abstracts and full-text publications for eligibility, and extracted data from each included publication. Ten publications were included in the scoping review. There was no trial evidence on support group benefits. All ten publications reported on the perceived benefits of participating in rare disease support groups. Three reported on barriers and facilitators of establishing and maintaining them. Overall, seven different perceived benefits of participating in rare disease support groups were identified: (1) meeting and befriending other people with the same rare disease and similar experiences; (2) learning about the disease and related treatments; (3) giving and receiving emotional support; (4) having a place to speak openly about the disease and one's feelings; (5) learning coping skills; (6) feeling empowered and hopeful; and (7) advocating to improve healthcare for other rare disease patients. Several facilitators (e.g., meeting via teleconference) and barriers (e.g., getting patients and/or family members to lead the group) of establishing and maintaining these

  17. Factors of importance for maintaining work as perceived by men with arthritis.

    PubMed

    Österholm, Johannes Hjalmarsson; Björk, Mathilda; Håkansson, Carita

    2013-01-01

    Employment rates are significantly lower among individuals with arthritis compared to a general population. There is, however, limited research about how men with arthritis perceive their ability to maintain working. The aim of this study was thus to explore their perception of this. Nine employed men with arthritis were purposively sampled. Interviews were performed and were informed by the central concepts of the Model of Human Occupation. The Empirical Phenomenological Psychological method was modified and used to analyze and interpret collected data. The findings showed that men with arthritis perceived a desire to work, adjusted their activity pattern, were aware of their own capabilities, had good work conditions, had environmental support and used effective medication to maintain their ability to work. The findings suggest that health care professionals can help men with arthritis to find strategies and a balance between recreation and work. Ultimately, this knowledge could guide health care professionals to target men needing interventions to prevent sick leave.

  18. Extraocular muscle regeneration in zebrafish requires late signals from Insulin-like growth factors.

    PubMed

    Saera-Vila, Alfonso; Louie, Ke'ale W; Sha, Cuilee; Kelly, Ryan M; Kish, Phillip E; Kahana, Alon

    2018-01-01

    Insulin-like growth factors (Igfs) are key regulators of key biological processes such as embryonic development, growth, and tissue repair and regeneration. The role of Igf in myogenesis is well documented and, in zebrafish, promotes fin and heart regeneration. However, the mechanism of action of Igf in muscle repair and regeneration is not well understood. Using adult zebrafish extraocular muscle (EOM) regeneration as an experimental model, we show that Igf1 receptor blockage using either chemical inhibitors (BMS754807 and NVP-AEW541) or translation-blocking morpholino oligonucleotides (MOs) reduced EOM regeneration. Zebrafish EOMs regeneration depends on myocyte dedifferentiation, which is driven by early epigenetic reprogramming and requires autophagy activation and cell cycle reentry. Inhibition of Igf signaling had no effect on either autophagy activation or cell proliferation, indicating that Igf signaling was not involved in the early reprogramming steps of regeneration. Instead, blocking Igf signaling produced hypercellularity of regenerating EOMs and diminished myosin expression, resulting in lack of mature differentiated muscle fibers even many days after injury, indicating that Igf was involved in late re-differentiation steps. Although it is considered the main mediator of myogenic Igf actions, Akt activation decreased in regenerating EOMs, suggesting that alternative signaling pathways mediate Igf activity in muscle regeneration. In conclusion, Igf signaling is critical for re-differentiation of reprogrammed myoblasts during late steps of zebrafish EOM regeneration, suggesting a regulatory mechanism for determining regenerated muscle size and timing of differentiation, and a potential target for regenerative therapy.

  19. Contribution of Toll-like receptor/myeloid differentiation factor 88 signaling to murine liver regeneration.

    PubMed

    Seki, Ekihiro; Tsutsui, Hiroko; Iimuro, Yuji; Naka, Tetsuji; Son, Gakuhei; Akira, Shizuo; Kishimoto, Tadamitsu; Nakanishi, Kenji; Fujimoto, Jiro

    2005-03-01

    Toll-like receptors (TLRs) act as innate immune signal sensors and play central roles in host defense. Myeloid differentiation factor (MyD) 88 is a common adaptor molecule required for signaling mediated by TLRs. When the receptors are activated, cells bearing TLRs produce various proinflammatory cytokines in a MyD88-dependent manner. Liver regeneration following partial hepatectomy (PH) requires innate immune responses, particularly interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) production by Kupffer cells, although the recognition and activation processes are still unknown. We investigated whether TLR/MyD88 signaling is critical for induction of innate immune responses after PH. In Myd88(-/-) mice after PH, induction of expression of immediate early genes involved in hepatocyte replication and phosphorylation of STAT3 in the liver, and production of TNF-alpha/IL-6 by and activation of NF-kappaB in the Kupffer cells were grossly subnormal and were associated with impaired liver regeneration. However, TLR2, 4 and 9, which recognize gram-negative and -positive bacterial products, are not essential for NF-kappaB activation and IL-6 production after PH, which excludes a possible contribution of TLR2/TLR4 or TLR9 to MyD88-mediated pathways. In conclusion, the TLR/MyD88 pathway is essential for incidental liver restoration, particularly its early phase.

  20. Fibroblast growth factor receptor signaling in hereditary and neoplastic disease: biologic and clinical implications.

    PubMed

    Helsten, Teresa; Schwaederle, Maria; Kurzrock, Razelle

    2015-09-01

    Fibroblast growth factors (FGFs) and their receptors (FGFRs) are transmembrane growth factor receptors with wide tissue distribution. FGF/FGFR signaling is involved in neoplastic behavior and also development, differentiation, growth, and survival. FGFR germline mutations (activating) can cause skeletal disorders, primarily dwarfism (generally mutations in FGFR3), and craniofacial malformation syndromes (usually mutations in FGFR1 and FGFR2); intriguingly, some of these activating FGFR mutations are also seen in human cancers. FGF/FGFR aberrations reported in cancers are mainly thought to be gain-of-function changes, and several cancers have high frequencies of FGFR alterations, including breast, bladder, or squamous cell carcinomas (lung and head and neck). FGF ligand aberrations (predominantly gene amplifications) are also frequently seen in cancers, in contrast to hereditary syndromes. There are several pharmacologic agents that have been or are being developed for inhibition of FGFR/FGF signaling. These include both highly selective inhibitors as well as multi-kinase inhibitors. Of note, only four agents (ponatinib, pazopanib, regorafenib, and recently lenvatinib) are FDA-approved for use in cancer, although the approval was not based on their activity against FGFR. Perturbations in the FGFR/FGF signaling are present in both inherited and malignant diseases. The development of potent inhibitors targeting FGF/FGFR may provide new tools against disorders caused by FGF/FGFR alterations.

  1. Directed random walks and constraint programming reveal active pathways in hepatocyte growth factor signaling.

    PubMed

    Kittas, Aristotelis; Delobelle, Aurélien; Schmitt, Sabrina; Breuhahn, Kai; Guziolowski, Carito; Grabe, Niels

    2016-01-01

    An effective means to analyze mRNA expression data is to take advantage of established knowledge from pathway databases, using methods such as pathway-enrichment analyses. However, pathway databases are not case-specific and expression data could be used to infer gene-regulation patterns in the context of specific pathways. In addition, canonical pathways may not always describe the signaling mechanisms properly, because interactions can frequently occur between genes in different pathways. Relatively few methods have been proposed to date for generating and analyzing such networks, preserving the causality between gene interactions and reasoning over the qualitative logic of regulatory effects. We present an algorithm (MCWalk) integrated with a logic programming approach, to discover subgraphs in large-scale signaling networks by random walks in a fully automated pipeline. As an exemplary application, we uncover the signal transduction mechanisms in a gene interaction network describing hepatocyte growth factor-stimulated cell migration and proliferation from gene-expression measured with microarray and RT-qPCR using in-house perturbation experiments in a keratinocyte-fibroblast co-culture. The resulting subgraphs illustrate possible associations of hepatocyte growth factor receptor c-Met nodes, differentially expressed genes and cellular states. Using perturbation experiments and Answer Set programming, we are able to select those which are more consistent with the experimental data. We discover key regulator nodes by measuring the frequency with which they are traversed when connecting signaling between receptors and significantly regulated genes and predict their expression-shift consistently with the measured data. The Java implementation of MCWalk is publicly available under the MIT license at: https://bitbucket.org/akittas/biosubg. © 2015 FEBS.

  2. Bid Promotes K63-Linked Polyubiquitination of Tumor Necrosis Factor Receptor Associated Factor 6 (TRAF6) and Sensitizes to Mutant SOD1-Induced Proinflammatory Signaling in Microglia123

    PubMed Central

    Kinsella, Sinéad

    2016-01-01

    Mutations in the superoxide dismutase 1 (SOD1) gene contribute to motoneuron degeneration and are evident in 20% of familial amyotrophic lateral sclerosis cases. Mutant SOD1 induces microglial activation through a stimulation of Toll-like receptors 2 and 4 (TLR2 and TLR4). In the present study, we identified the proapoptotic Bcl-2 family protein Bid as a positive regulator of mutant SOD1-induced TLR-nuclear factor-κB (NF-κB) signaling in microglia. bid-deficient primary mouse microglia showed reduced NF-κB signaling in response to TLR4 activation or exposure to conditioned medium derived from SOD1 G93A expressing NSC-34 cells. Attenuation of NF-κB signaling in bid-deficient microglia was associated with lower levels of phosphorylated IKKα/β and p65, with a delayed degradation of IκBα and enhanced degradation of Peli1. Upstream of IKK, we found that Bid interacted with, and promoted, the K63-linked polyubiquitination of the E3 ubiquitin ligase tumor necrosis factor receptor associated factor 6 (TRAF6) in microglia. Our study suggests a key role for Bid in the regulation of TLR4-NF-κB proinflammatory signaling during mutant SOD1-induced disease pathology. Bid promotes TLR4-NF-κB signaling by interacting with TRAF6 and promoting TRAF6 K63-linked polyubiquitination in microglia. PMID:27257617

  3. Intentions to Maintain Adherence to Mammography

    PubMed Central

    Bowling, J. Michael; Brewer, Noel T.; Lipkus, Isaac M.; Skinner, Celette Sugg; Strigo, Tara S.; Rimer, Barbara K.

    2008-01-01

    Abstract Objective Recent attention has focused on moving women from having initial mammograms to maintaining adherence to regular mammography schedules. We examined behavioral intentions to maintain mammography adherence, which include the likelihood of performing a behavior, and implementation intentions, specific action plans to obtain mammograms. Potential predictors were Theory of Planned Behavior constructs, previous barriers, previous mammography maintenance, and age. Methods Respondents were 2062 currently adherent women due for their next mammograms in 3–4 months according to American Cancer Society recommendations for annual screening. Statistical models were used to examine predictors of behavioral and two implementation intentions, including having thought about where women would get their next mammograms and having thought about making appointments. Results With the exception of pros, cons, and subjective norms, all variables predicted behavioral intentions (p ≤ 0.05). Stronger perceived control, previous mammography maintenance, and one barrier (vs. none) predicted being more likely to have thought about where to get their next mammograms. Previous maintenance and no barriers (vs. two) predicted being more likely to have thought about making appointments. Conclusions Our findings suggest that among women currently adherent to mammography, volitional factors, such as barriers, may be better predictors of implementation intentions than motivational factors, such as attitudes. Implementation variables may be useful in understanding how women move from intentions to action. Future research should examine how such factors relate to mammography maintenance behaviors and can be integrated into behavior change interventions. PMID:18657041

  4. Work Environment-Related Factors in Obtaining and Maintaining Work in a Competitive Employment Setting for Employees with Intellectual Disabilities: A Systematic Review.

    PubMed

    Ellenkamp, Joke J H; Brouwers, Evelien P M; Embregts, Petri J C M; Joosen, Margot C W; van Weeghel, Jaap

    2016-03-01

    People with an intellectual disability value work as a significant part of their lives, and many of them want to participate in regular paid employment.Current estimates show that the number of people with ID who have some form of paid employment are very low, ranging from 9 to 40% across different countries,despite legislations. This review examines papers published in the past 20 years in an attempt to answer the following research question: ‘What work environment-related factors contribute to obtaining or maintaining work in competitive employment for people with an intellectual disability?’ The databases of PubMed, PsycINFO,CINAHL, Embase and Web of Science were searched for relevant papers published between 1993 and 2013. All papers were independently screened by two researchers.Methodological quality of the studies was evaluated, and data on work environment-related factors stimulating employment for people with intellectual disabilities were extracted and grouped into categories. A total of 1932 articles were retrieved. After extensive screening for relevance and quality, 26 articles were included in this review. Four themes/categories with work environment related factors that could influence work participation were distinguished. Five studies were conducted on employers’ decisions and opinions. Eight focused on job content and performance, and eight on workplace interaction and culture. Five studies evaluated support by job coaches. Despite ongoing legislation to promote participation of people with intellectual disabilities in the paid workforce, research in this area is still extremely scarce. In the past 20 years, very few studies have focused on work environment-related factors that can enhance competitive work for people with intellectual disabilities.This review shows that relevant work environment-related factors for obtaining and maintaining work in competitive employment include supporting the employers by paying specific attention to

  5. The adrenal capsule is a signaling center controlling cell renewal and zonation through Rspo3

    PubMed Central

    Vidal, Valerie; Sacco, Sonia; Rocha, Ana Sofia; da Silva, Fabio; Panzolini, Clara; Dumontet, Typhanie; Doan, Thi Mai Phuong; Shan, Jingdong; Rak-Raszewska, Aleksandra; Bird, Tom; Vainio, Seppo; Martinez, Antoine; Schedl, Andreas

    2016-01-01

    Adrenal glands are zonated endocrine organs that are essential in controlling body homeostasis. How zonation is induced and maintained and how renewal of the adrenal cortex is ensured remain a mystery. Here we show that capsular RSPO3 signals to the underlying steroidogenic compartment to induce β-catenin signaling and imprint glomerulosa cell fate. Deletion of RSPO3 leads to loss of SHH signaling and impaired organ growth. Importantly, Rspo3 function remains essential in adult life to ensure replenishment of lost cells and maintain the properties of the zona glomerulosa. Thus, the adrenal capsule acts as a central signaling center that ensures replacement of damaged cells and is required to maintain zonation throughout life. PMID:27313319

  6. Getting and maintaining attention in talk to young children.

    PubMed

    Estigarribia, Bruno; Clark, Eve V

    2007-11-01

    When two people talk about an object, they depend on joint attention, a prerequisite for setting up common ground in a conversational exchange. In this study, we analyze this process for parent and child, with data from 40 dyads, to show how adults initiate joint attention in talking to young children (mean ages 1;6 and 3;0). Adults first get their children's attention with a summons (e.g. Ready?, See this?), but cease using such forms once children give evidence of attending. Children signal their attention by looking at the target object, evidence used by the adults. Only at that point do adults begin to talk about the object. From then on, they use language and gesture to offer information about and maintain attention on the target. The techniques adults rely on are interactive: they establish joint attention and maintain it throughout the exchange.

  7. The Drosophila T-box transcription factor Midline functions within the Notch-Delta signaling pathway to specify sensory organ precursor cell fates and regulates cell survival within the eye imaginal disc.

    PubMed

    Das, Sudeshna; Chen, Q Brent; Saucier, Joseph D; Drescher, Brandon; Zong, Yan; Morgan, Sarah; Forstall, John; Meriwether, Andrew; Toranzo, Randy; Leal, Sandra M

    2013-01-01

    We report that the T-box transcription factor Midline (Mid), an evolutionary conserved homolog of the vertebrate Tbx20 protein, functions within the Notch-Delta signaling pathway essential for specifying the fates of sensory organ precursor (SOP) cells. These findings complement an established history of research showing that Mid regulates the cell-fate specification of diverse cell types within the developing heart, epidermis and central nervous system. Tbx20 has been detected in unique neuronal and epithelial cells of embryonic eye tissues in both mice and humans. However, the mechanisms by which either Mid or Tbx20 function to regulate cell-fate specification or other critical aspects of eye development including cell survival have not yet been elucidated. We have also gathered preliminary evidence suggesting that Mid may play an indirect, but vital role in selecting SOP cells within the third-instar larval eye disc by regulating the expression of the proneural gene atonal. During subsequent pupal stages, Mid specifies SOP cell fates as a member of the Notch-Delta signaling hierarchy and is essential for maintaining cell viability by inhibiting apoptotic pathways. We present several new hypotheses that seek to understand the role of Mid in regulating developmental processes downstream of the Notch receptor that are critical for specifying unique cell fates, patterning the adult eye and maintaining cellular homeostasis during eye disc morphogenesis. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  8. The Emerging Role of Insulin and Insulin-Like Growth Factor Signaling in Cancer Stem Cells

    PubMed Central

    Malaguarnera, Roberta; Belfiore, Antonino

    2014-01-01

    Cancer cells frequently exploit the IGF signaling, a fundamental pathway mediating development, cell growth, and survival. As a consequence, several components of the IGF signaling are deregulated in cancer and sustain cancer progression. However, specific targeting of IGF-IR in humans has resulted efficacious only in small subsets of cancers, making researches wondering whether IGF system targeting is still worth pursuing in the clinical setting. Although no definite answer is yet available, it has become increasingly clear that other components of the IGF signaling pathway, such as IR-A, may substitute for the lack of IGF-IR, and induce cancer resistance and/or clonal selection. Moreover, accumulating evidence now indicates that IGF signaling is a central player in the induction/maintenance of epithelial mesenchymal transition (EMT) and cell stemness, two strictly related programs, which play a key role in metastatic spread and resistance to cancer treatments. Here we review the evidences indicating that IGF signaling enhances the expression of transcription factors implicated in the EMT program and has extensive cross-talk with specific pathways involved in cell pluripotency and stemness maintenance. In turn, EMT and cell stemness activate positive feed-back mechanisms causing up-regulation of various IGF signaling components. These findings may have novel translational implications. PMID:24550888

  9. Loss of Dlg-1 in the Mouse Lens Impairs Fibroblast Growth Factor Receptor Signaling

    PubMed Central

    Lee, SungKyoung; Griep, Anne E.

    2014-01-01

    Coordination of cell proliferation, differentiation and survival is essential for normal development and maintenance of tissues in the adult organism. Growth factor receptor tyrosine kinase signaling pathways and planar cell polarity pathways are two regulators of many developmental processes. We have previously shown through analysis of mice conditionally null in the lens for the planar cell polarity gene (PCP), Dlg-1, that Dlg-1 is required for fiber differentiation. Herein, we asked if Dlg-1 is a regulator of the Fibroblast growth factor receptor (Fgfr) signaling pathway, which is known to be required for fiber cell differentiation. Western blot analysis of whole fiber cell extracts from control and Dlg-1 deficient lenses showed that levels of the Fgfr signaling intermediates pErk, pAkt, and pFrs2α, the Fgfr target, Erm, and the fiber cell specific protein, Mip26, were reduced in the Dlg-1 deficient fiber cells. The levels of Fgfr2 were decreased in Dlg-1 deficient lenses compared to controls. Conversely, levels of Fgfr1 in Dlg-1 deficient lenses were increased compared to controls. The changes in Fgfr levels were found to be specifically in the triton insoluble, cytoskeletal associated fraction of Dlg-1 deficient lenses. Immunofluorescent staining of lenses from E13.5 embryos showed that expression levels of pErk were reduced in the transition zone, a region of the lens that exhibits PCP, in the Dlg-1 deficient lenses as compared to controls. In control lenses, immunofluorescent staining for Fgfr2 was observed in the epithelium, transition zone and fibers. By E13.5, the intensity of staining for Fgfr2 was reduced in these regions of the Dlg-1 deficient lenses. Thus, loss of Dlg-1 in the lens impairs Fgfr signaling and leads to altered levels of Fgfrs, suggesting that Dlg-1 is a modulator of Fgfr signaling pathway at the level of the receptors and that Dlg-1 regulates fiber cell differentiation through its role in PCP. PMID:24824078

  10. Factors of transforming growth factor beta signalling are co-regulated in human hepatocellular carcinoma.

    PubMed

    Longerich, Thomas; Breuhahn, Kai; Odenthal, Margarete; Petmecky, Katharina; Schirmacher, Peter

    2004-12-01

    Transforming growth factor beta (TGFbeta) is a central mitoinhibitory factor for epithelial cells, and alterations of TGFbeta signalling have been demonstrated in many different human cancers. We have analysed human hepatocellular carcinomas (HCCs) for potential pro-tumourigenic alterations in regard to expression of Smad4 and mutations and expression changes of the pro-oncogenic transcriptional co-repressors Ski and SnoN, as well as mRNA levels of matrix metalloproteinase-2 (MMP2), which is transcriptionally regulated by TGFbeta. Smad4 mRNA was detected in all HCCs; while, using immunohistology, loss of Smad4 expression was found in 10% of HCCs. Neither mutations in the transformation-relevant sequences nor significant pro-tumourigenic expression changes of the Ski and SnoN genes were detected. In HCC cell lines, expression of both genes was regulated, potentially involving phosphorylation. Ski showed a distinct nuclear speckled pattern, indicating recruitment to active transcription complexes. MMP2 mRNA levels were increased in 19% of HCCs, whereas MMP2 mRNA was not detectable in HCC cell lines, suggesting that MMP2 was derived only from tumour stroma cells. Transcript levels of Smad4, Ski, SnoN and MMP2 correlated well. These data argue against a significant role of Ski and SnoN in human hepatocarcinogenesis and suggest that, in the majority of HCCs, the analysed factors are co-regulated by an upstream mechanism, potentially by TGFbeta itself.

  11. Toxicological disruption of signaling homeostasis: Tyrosine phosphatses as targets

    EPA Science Inventory

    The protein tyrosine phosphatases (PTP) comprised a diverse group of enzymes whose activity opposes that of the tyrosine kinases. As such, the PTP have critical roles in maintaining signaling quiescence in resting cells and in restoring homeostasis by effecting signal termination...

  12. Sp5 induces the expression of Nanog to maintain mouse embryonic stem cell self-renewal.

    PubMed

    Tang, Ling; Wang, Manman; Liu, Dahai; Gong, Mengting; Ying, Qi-Long; Ye, Shoudong

    2017-01-01

    Activation of signal transducer and activator of transcription 3 (STAT3) by leukemia inhibitory factor (LIF) maintains mouse embryonic stem cell (mESC) self-renewal. Our previous study showed that trans-acting transcription factor 5 (Sp5), an LIF/STAT3 downstream target, supports mESC self-renewal. However, the mechanism by which Sp5 exerts these effects remains elusive. Here, we found that Nanog is a direct target of Sp5 and mediates the self-renewal-promoting effect of Sp5 in mESCs. Overexpression of Sp5 induced Nanog expression, while knockdown or knockout of Sp5 decreased the Nanog level. Moreover, chromatin immunoprecipitation (ChIP) assays showed that Sp5 directly bound to the Nanog promoter. Functional studies revealed that knockdown of Nanog eliminated the mESC self-renewal-promoting ability of Sp5. Finally, we demonstrated that the self-renewal-promoting function of Sp5 was largely dependent on its zinc finger domains. Taken together, our study provides unrecognized functions of Sp5 in mESCs and will expand our current understanding of the regulation of mESC pluripotency.

  13. Basic Aspects of Tumor Cell Fatty Acid-Regulated Signaling and Transcription Factors

    PubMed Central

    Comba, Andrea; Lin, Yi-Hui; Eynard, Aldo Renato; Valentich, Mirta Ana; Fernandez-Zapico, Martin Ernesto; Pasqualini, Marìa Eugenia

    2012-01-01

    This article reviews the current knowledge and experimental research about the mechanisms by which fatty acids and their derivatives control specific gene expression involved during carcinogenesis. Changes in dietary fatty acids, specifically the polyunsaturated fatty acids (PUFAs) of the ω-3 and ω-6 families and some derived eicosanoids from lipoxygenases (LOXs), cyclooxygenases (COXs), and cytochrome P-450 (CYP-450), seem to control the activity of transcription factor families involved in cancer cell proliferation or cell death. Their regulation may be carried out either through direct binding to DNA as peroxisome proliferator–activated receptors (PPARs) or via modulation in an indirect manner of signaling pathway molecules (e.g., protein kinase C [PKC]) and other transcription factors (nuclear factor kappa B [NFκB] and sterol regulatory element binding protein [SREBP]). Knowledge of the mechanisms by which fatty acids control specific gene expression may identify important risk factors for cancer, and provide insight into the development of new therapeutic strategies for a better management of whole-body lipid metabolism. PMID:22048864

  14. Chromatin-Remodeling-Factor ARID1B Represses Wnt/β-Catenin Signaling.

    PubMed

    Vasileiou, Georgia; Ekici, Arif B; Uebe, Steffen; Zweier, Christiane; Hoyer, Juliane; Engels, Hartmut; Behrens, Jürgen; Reis, André; Hadjihannas, Michel V

    2015-09-03

    The link of chromatin remodeling to both neurodevelopment and cancer has recently been highlighted by the identification of mutations affecting BAF chromatin-remodeling components, such as ARID1B, in individuals with intellectual disability and cancer. However, the underlying molecular mechanism(s) remains unknown. Here, we show that ARID1B is a repressor of Wnt/β-catenin signaling. Through whole-transcriptome analysis, we find that in individuals with intellectual disability and ARID1B loss-of-function mutations, Wnt/β-catenin target genes are upregulated. Using cellular models of low and high Wnt/β-catenin activity, we demonstrate that knockdown of ARID1B activates Wnt/β-catenin target genes and Wnt/β-catenin-dependent transcriptional reporters in a β-catenin-dependent manner. Reciprocally, forced expression of ARID1B inhibits Wnt/β-catenin signaling downstream of the β-catenin destruction complex. Both endogenous and exogenous ARID1B associate with β-catenin and repress Wnt/β-catenin-mediated transcription through the BAF core subunit BRG1. Accordingly, mutations in ARID1B leading to partial or complete deletion of its BRG1-binding domain, as is often observed in intellectual disability and cancers, compromise association with β-catenin, and the resultant ARID1B mutant proteins fail to suppress Wnt/β-catenin signaling. Finally, knockdown of ARID1B in mouse neuroblastoma cells leads to neurite outgrowth through β-catenin. The data suggest that aberrations in chromatin-remodeling factors, such as ARID1B, might contribute to neurodevelopmental abnormalities and cancer through deregulation of developmental and oncogenic pathways, such as the Wnt/β-catenin signaling pathway. Copyright © 2015 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

  15. Alteration in mitochondrial Ca(2+) uptake disrupts insulin signaling in hypertrophic cardiomyocytes.

    PubMed

    Gutiérrez, Tomás; Parra, Valentina; Troncoso, Rodrigo; Pennanen, Christian; Contreras-Ferrat, Ariel; Vasquez-Trincado, César; Morales, Pablo E; Lopez-Crisosto, Camila; Sotomayor-Flores, Cristian; Chiong, Mario; Rothermel, Beverly A; Lavandero, Sergio

    2014-11-07

    Cardiac hypertrophy is characterized by alterations in both cardiac bioenergetics and insulin sensitivity. Insulin promotes glucose uptake by cardiomyocytes and its use as a substrate for glycolysis and mitochondrial oxidation in order to maintain the high cardiac energy demands. Insulin stimulates Ca(2+) release from the endoplasmic reticulum, however, how this translates to changes in mitochondrial metabolism in either healthy or hypertrophic cardiomyocytes is not fully understood. In the present study we investigated insulin-dependent mitochondrial Ca(2+) signaling in normal and norepinephrine or insulin like growth factor-1-induced hypertrophic cardiomyocytes. Using mitochondrion-selective Ca(2+)-fluorescent probes we showed that insulin increases mitochondrial Ca(2+) levels. This signal was inhibited by the pharmacological blockade of either the inositol 1,4,5-triphosphate receptor or the mitochondrial Ca(2+) uniporter, as well as by siRNA-dependent mitochondrial Ca(2+) uniporter knockdown. Norepinephrine-stimulated cardiomyocytes showed a significant decrease in endoplasmic reticulum-mitochondrial contacts compared to either control or insulin like growth factor-1-stimulated cells. This resulted in a reduction in mitochondrial Ca(2+) uptake, Akt activation, glucose uptake and oxygen consumption in response to insulin. Blocking mitochondrial Ca(2+) uptake was sufficient to mimic the effect of norepinephrine-induced cardiomyocyte hypertrophy on insulin signaling. Mitochondrial Ca(2+) uptake is a key event in insulin signaling and metabolism in cardiomyocytes.

  16. Overexpression of SIRT1 Protects Pancreatic β-Cells Against Cytokine Toxicity by Suppressing the Nuclear Factor-κB Signaling Pathway

    PubMed Central

    Lee, Ji-Hyun; Song, Mi-Young; Song, Eun-Kyung; Kim, Eun-Kyung; Moon, Woo Sung; Han, Myung-Kwan; Park, Jin-Woo; Kwon, Kang-Beom; Park, Byung-Hyun

    2009-01-01

    OBJECTIVE—SIRT1, a class III histone/protein deacetylase, is known to interfere with the nuclear factor-κB (NF-κB) signaling pathway and thereby has an anti-inflammatory function. Because of the central role of NF-κB in cytokine-mediated pancreatic β-cell damage, we postulated that SIRT1 might work in pancreatic β-cell damage models. RESEARCH DESIGN AND METHODS—RINm5F (RIN) cells or isolated rat islets were treated with interleukin-1β and interferon-γ. SIRT1 was activated by resveratrol, a pharmacological activator, or ectopic overexpression. The underlying mechanisms of SIRT1 against cytokine toxicity were further explored. RESULTS—Treatment of RIN cells with cytokines induced cell damage, and this damage was well correlated with the expression of the inducible form of nitric oxide (NO) synthase (iNOS) and NO production. However, SIRT1 overexpression completely prevented cytokine-mediated cytotoxicity, NO production, and iNOS expression. The molecular mechanism by which SIRT1 inhibits iNOS expression appeared to involve the inhibition of the NF-κB signaling pathway through deacetylation of p65. In addition, SIRT1 activation by either resveratrol or adenoviral-directed overexpression of SIRT1 could prevent cytokine toxicity and maintain normal insulin-secreting responses to glucose in isolated rat islets. CONCLUSIONS—This study will provide valuable information not only into the mechanisms underlying β-cell destruction but also into the regulation of SIRT1 as a possible target to attenuate cytokine-induced β-cell damage. PMID:19008341

  17. Fgf Signaling is Required for Photoreceptor Maintenance in the Adult Zebrafish Retina

    PubMed Central

    Hochmann, Sarah; Kaslin, Jan; Hans, Stefan; Weber, Anke; Machate, Anja; Geffarth, Michaela; Funk, Richard H. W.; Brand, Michael

    2012-01-01

    Fibroblast growth factors (Fgf) are secreted signaling molecules that have mitogenic, patterning, neurotrophic and angiogenic properties. Their importance during embryonic development in patterning and morphogenesis of the vertebrate eye is well known, but less is known about the role of Fgfs in the adult vertebrate retina. To address Fgf function in adult retina, we determined the spatial distribution of components of the Fgf signaling pathway in the adult zebrafish retina. We detected differential expression of Fgf receptors, ligands and downstream Fgf targets within specific retinal layers. Furthermore, we blocked Fgf signaling in the retina, by expressing a dominant negative variant of Fgf receptor 1 conditionally in transgenic animals. After blocking Fgf signaling we observe a fast and progressive photoreceptor degeneration and disorganization of retinal tissue, coupled with cell death in the outer nuclear layer. Following the degeneration of photoreceptors, a profound regeneration response is triggered that starts with proliferation in the inner nuclear layer. Ultimately, rod and cone photoreceptors are regenerated completely. Our study reveals the requirement of Fgf signaling to maintain photoreceptors and for proliferation during regeneration in the adult zebrafish retina. PMID:22291943

  18. Sex Differences in Brain-Derived Neurotrophic Factor Signaling and Functions

    PubMed Central

    Chan, Chi Bun; Ye, Keqiang

    2016-01-01

    Brain derived neurotrophic factor (BDNF) is a member of the neurotrophin family that plays a critical role in numerous neuronal activities. Recent studies report that some functions or action mechanisms of BDNF vary in a sex-dependent manner. In particular, BDNF content in some brain parts and the tendency of developing BDNF-deficient-related diseases like depression is higher in female animals. With the support of other relevant studies, it is suggested that sex hormones or steroids can modulate the activities of BDNF, which may account for its functional discrepancy in different sexes. Indeed, the cross-talk between BDNF and sex steroids has been detected for decades and some sex steroids like estrogen have a positive regulatory effect to BDNF expression and signaling. Thus, the sex of animal models used is critical when studying the functions of BDNF in vivo. In this review, we will summarize our current findings on the difference in expression, signaling, and functions of BDNF between sexes. We will also discuss the potential mechanisms in mediating these differential responses with a specific emphasis on sex steroids. By presenting and discussing these findings, we encourage taking sex influences into consideration when designing experiments, interpreting results and drawing conclusions. PMID:27870419

  19. 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

  20. Amplification of the EGFR gene can be maintained and modulated by variation of EGF concentrations in in vitro models of glioblastoma multiforme

    PubMed Central

    Mokri, Poroshista; Lamp, Nora; Linnebacher, Michael; Classen, Carl Friedrich; Erbersdobler, Andreas; Schneider, Björn

    2017-01-01

    Glioblastoma multiforme (GBM) is the most common and lethal brain tumor in adults. It is known that amplification of the epidermal growth factor receptor gene (EGFR) occurs in approximately 40% of GBM, leading to enhanced activation of the EGFR signaling pathway and promoting tumor growth. Although GBM mutations are stably maintained in GBM in vitro models, rapid loss of EGFR gene amplification is a common observation during cell culture. To maintain EGFR amplification in vitro, heterotopic GBM xenografts with elevated EGFR copy number were cultured under varying serum conditions and EGF concentrations. EGFR copy numbers were assessed over several passages by quantitative PCR and chromogenic in situ hybridization. As expected, in control assays with 10% FCS, cells lost EGFR amplification with increasing passage numbers. However, cells cultured under serum free conditions stably maintained elevated copy numbers. Furthermore, EGFR protein expression positively correlated with genomic amplification levels. Although elevated EGFR copy numbers could be maintained over several passages in vitro, levels of EGFR amplification were variable and dependent on the EGF concentration in the medium. In vitro cultures of GBM cells with elevated EGFR copy number and corresponding EGFR protein expression should prove valuable preclinical tools to gain a better understanding of EGFR driven glioblastoma and assist in the development of new improved therapies. PMID:28934307

  1. Motion-based signaling in sympatric species of Australian agamid lizards.

    PubMed

    Ramos, Jose A; Peters, Richard A

    2017-08-01

    Signaling species occurring in sympatry are often exposed to similar environmental constraints, so similar adaptations to enhance signal efficacy are expected. However, potentially opposing selective pressures might be present to ensure species recognition. Here, we analyzed the movement-based signals of two pairs of sympatric lizard species to consider how reliable communication is maintained while avoiding misidentification. Our novel approach allows us to quantify signal contrast with plant motion noise at any site we measure, including those utilized by other species. Ctenophorus caudicinctus and Gowidon longirostris differed in display complexity and motor pattern use. They also differed in overall morphology, but their signal contrast scores are strikingly similar. These results demonstrate similar adaptations to their shared environment while maintaining species recognition cues. In contrast, Ctenophorus fordi and Ctenophorus pictus are much closer in appearance, but C. pictus produces considerably higher signal contrast scores, which we suggest is attributable to the absence of territoriality in C. fordi. Taken together, our data provide evidence for adaptation to the local environment in movement-based signals, while also meeting species recognition requirements, but the selective pressure to deal with local conditions is mediated by signal function.

  2. Adaptive and Innate Transforming Growth Factor β Signaling Impact Herpes Simplex Virus 1 Latency and Reactivation▿

    PubMed Central

    Allen, Sariah J.; Mott, Kevin R.; Wechsler, Steven L.; Flavell, Richard A.; Town, Terrence; Ghiasi, Homayon

    2011-01-01

    Innate and adaptive immunity play important protective roles by combating herpes simplex virus 1 (HSV-1) infection. Transforming growth factor β (TGF-β) is a key negative cytokine regulator of both innate and adaptive immune responses. Yet, it is unknown whether TGF-β signaling in either immune compartment impacts HSV-1 replication and latency. We undertook genetic approaches to address these issues by infecting two different dominant negative TGF-β receptor type II transgenic mouse lines. These mice have specific TGF-β signaling blockades in either T cells or innate cells. Mice were ocularly infected with HSV-1 to evaluate the effects of restricted innate or adaptive TGF-β signaling during acute and latent infections. Limiting innate cell but not T cell TGF-β signaling reduced virus replication in the eyes of infected mice. On the other hand, blocking TGF-β signaling in either innate cells or T cells resulted in decreased latency in the trigeminal ganglia of infected mice. Furthermore, inhibiting TGF-β signaling in T cells reduced cell lysis and leukocyte infiltration in corneas and trigeminal ganglia during primary HSV-1 infection of mice. These findings strongly suggest that TGF-β signaling, which generally functions to dampen immune responses, results in increased HSV-1 latency. PMID:21880769

  3. The adrenal capsule is a signaling center controlling cell renewal and zonation through Rspo3.

    PubMed

    Vidal, Valerie; Sacco, Sonia; Rocha, Ana Sofia; da Silva, Fabio; Panzolini, Clara; Dumontet, Typhanie; Doan, Thi Mai Phuong; Shan, Jingdong; Rak-Raszewska, Aleksandra; Bird, Tom; Vainio, Seppo; Martinez, Antoine; Schedl, Andreas

    2016-06-15

    Adrenal glands are zonated endocrine organs that are essential in controlling body homeostasis. How zonation is induced and maintained and how renewal of the adrenal cortex is ensured remain a mystery. Here we show that capsular RSPO3 signals to the underlying steroidogenic compartment to induce β-catenin signaling and imprint glomerulosa cell fate. Deletion of RSPO3 leads to loss of SHH signaling and impaired organ growth. Importantly, Rspo3 function remains essential in adult life to ensure replenishment of lost cells and maintain the properties of the zona glomerulosa. Thus, the adrenal capsule acts as a central signaling center that ensures replacement of damaged cells and is required to maintain zonation throughout life. © 2016 Vidal et al.; Published by Cold Spring Harbor Laboratory Press.

  4. Protein disulfide isomerase acts as an injury response signal that enhances fibrin generation via tissue factor activation

    PubMed Central

    Reinhardt, Christoph; von Brühl, Marie-Luise; Manukyan, Davit; Grahl, Lenka; Lorenz, Michael; Altmann, Berid; Dlugai, Silke; Hess, Sonja; Konrad, Ildiko; Orschiedt, Lena; Mackman, Nigel; Ruddock, Lloyd; Massberg, Steffen; Engelmann, Bernd

    2008-01-01

    The activation of initiator protein tissue factor (TF) is likely to be a crucial step in the blood coagulation process, which leads to fibrin formation. The stimuli responsible for inducing TF activation are largely undefined. Here we show that the oxidoreductase protein disulfide isomerase (PDI) directly promotes TF-dependent fibrin production during thrombus formation in vivo. After endothelial denudation of mouse carotid arteries, PDI was released at the injury site from adherent platelets and disrupted vessel wall cells. Inhibition of PDI decreased TF-triggered fibrin formation in different in vivo murine models of thrombus formation, as determined by intravital fluorescence microscopy. PDI infusion increased — and, under conditions of decreased platelet adhesion, PDI inhibition reduced — fibrin generation at the injury site, indicating that PDI can directly initiate blood coagulation. In vitro, human platelet–secreted PDI contributed to the activation of cryptic TF on microvesicles (microparticles). Mass spectrometry analyses indicated that part of the extracellular cysteine 209 of TF was constitutively glutathionylated. Mixed disulfide formation contributed to maintaining TF in a state of low functionality. We propose that reduced PDI activates TF by isomerization of a mixed disulfide and a free thiol to an intramolecular disulfide. Our findings suggest that disulfide isomerases can act as injury response signals that trigger the activation of fibrin formation following vessel injury. PMID:18274674

  5. Protein disulfide isomerase acts as an injury response signal that enhances fibrin generation via tissue factor activation.

    PubMed

    Reinhardt, Christoph; von Brühl, Marie-Luise; Manukyan, Davit; Grahl, Lenka; Lorenz, Michael; Altmann, Berid; Dlugai, Silke; Hess, Sonja; Konrad, Ildiko; Orschiedt, Lena; Mackman, Nigel; Ruddock, Lloyd; Massberg, Steffen; Engelmann, Bernd

    2008-03-01

    The activation of initiator protein tissue factor (TF) is likely to be a crucial step in the blood coagulation process, which leads to fibrin formation. The stimuli responsible for inducing TF activation are largely undefined. Here we show that the oxidoreductase protein disulfide isomerase (PDI) directly promotes TF-dependent fibrin production during thrombus formation in vivo. After endothelial denudation of mouse carotid arteries, PDI was released at the injury site from adherent platelets and disrupted vessel wall cells. Inhibition of PDI decreased TF-triggered fibrin formation in different in vivo murine models of thrombus formation, as determined by intravital fluorescence microscopy. PDI infusion increased - and, under conditions of decreased platelet adhesion, PDI inhibition reduced - fibrin generation at the injury site, indicating that PDI can directly initiate blood coagulation. In vitro, human platelet-secreted PDI contributed to the activation of cryptic TF on microvesicles (microparticles). Mass spectrometry analyses indicated that part of the extracellular cysteine 209 of TF was constitutively glutathionylated. Mixed disulfide formation contributed to maintaining TF in a state of low functionality. We propose that reduced PDI activates TF by isomerization of a mixed disulfide and a free thiol to an intramolecular disulfide. Our findings suggest that disulfide isomerases can act as injury response signals that trigger the activation of fibrin formation following vessel injury.

  6. Cell-cycle quiescence maintains Caenorhabditis elegans germline stem cells independent of GLP-1/Notch

    PubMed Central

    Seidel, Hannah S; Kimble, Judith

    2015-01-01

    Many types of adult stem cells exist in a state of cell-cycle quiescence, yet it has remained unclear whether quiescence plays a role in maintaining the stem cell fate. Here we establish the adult germline of Caenorhabditis elegans as a model for facultative stem cell quiescence. We find that mitotically dividing germ cells—including germline stem cells—become quiescent in the absence of food. This quiescence is characterized by a slowing of S phase, a block to M-phase entry, and the ability to re-enter M phase rapidly in response to re-feeding. Further, we demonstrate that cell-cycle quiescence alters the genetic requirements for stem cell maintenance: The signaling pathway required for stem cell maintenance under fed conditions—GLP-1/Notch signaling—becomes dispensable under conditions of quiescence. Thus, cell-cycle quiescence can itself maintain stem cells, independent of the signaling pathway otherwise essential for such maintenance. DOI: http://dx.doi.org/10.7554/eLife.10832.001 PMID:26551561

  7. Coordinated regulation of Arabidopsis microRNA biogenesis and red light signaling through Dicer-like 1 and phytochrome-interacting factor 4

    PubMed Central

    Sun, Zhenfei; Li, Min; Zhou, Ying; Guo, Tongtong; Liu, Yin; Zhang, Hui

    2018-01-01

    Light and microRNAs (miRNAs) are key external and internal signals for plant development, respectively. However, the relationship between the light signaling and miRNA biogenesis pathways remains unknown. Here we found that miRNA processer proteins DCL1 and HYL1 interact with a basic helix-loop-helix (bHLH) transcription factor, phytochrome-interacting factor 4 (PIF4), which mediates the destabilization of DCL1 during dark-to-red-light transition. PIF4 acts as a transcription factor for some miRNA genes and is necessary for the proper accumulation of miRNAs. DCL1, HYL1, and mature miRNAs play roles in the regulation of plant hypocotyl growth. These results uncovered a previously unknown crosstalk between miRNA biogenesis and red light signaling through the PIF4-dependent regulation of miRNA transcription and processing to affect red-light-directed plant photomorphogenesis. PMID:29522510

  8. Inhibitors of Intracellular Signaling Pathways that Lead to Stimulated Epidermal Pigmentation: Perspective of Anti-Pigmenting Agents

    PubMed Central

    Imokawa, Genji; Ishida, Koichi

    2014-01-01

    Few anti-pigmenting agents have been designed and developed according to their known hyperpigmentation mechanisms and corresponding intracellular signaling cascades. Most anti-pigmenting agents developed so far are mechanistically involved in the interruption of constitutional melanogenic mechanisms by which skin color is maintained at a normal and unstimulated level. Thus, owing to the difficulty of confining topical application to a specific hyperpigmented skin area, potent anti-pigmenting agents capable of attenuating the natural unstimulated pigmentation process have the risk of leading to hypopigmentation. Since intracellular signaling pathways within melanocytes do not function substantially in maintaining normal skin color and are activated only by environmental stimuli such as UV radiation, specifically down-regulating the activation of melanogenesis to the constitutive level would be an appropriate strategy to develop new potent anti-pigmenting agents with a low risk of hypopigmentation. In this article, we review the hyperpigmentation mechanisms and intracellular signaling pathways that lead to the stimulation of melanogenesis. We also discuss a screening and evaluation system to select candidates for new anti-melanogenic substances by focusing on inhibitors of endothelin-1 or stem cell factor-triggered intracellular signaling cascades. From this viewpoint, we show that extracts of the herbs Withania somnifera and Melia toosendan and the natural chemicals Withaferin A and Astaxanthin are new candidates for potent anti-pigmenting substances that avoid the risk of hypopigmentation. PMID:24823877

  9. CTGF Mediates Smad-Dependent Transforming Growth Factor β Signaling To Regulate Mesenchymal Cell Proliferation during Palate Development

    PubMed Central

    Parada, Carolina; Li, Jingyuan; Iwata, Junichi; Suzuki, Akiko

    2013-01-01

    Transforming growth factor β (TGF-β) signaling plays crucial functions in the regulation of craniofacial development, including palatogenesis. Here, we have identified connective tissue growth factor (Ctgf) as a downstream target of the TGF-β signaling pathway in palatogenesis. The pattern of Ctgf expression in wild-type embryos suggests that it may be involved in key processes during palate development. We found that Ctgf expression is downregulated in both Wnt1-Cre; Tgfbr2fl/fl and Osr2-Cre; Smad4fl/fl palates. In Tgfbr2 mutant embryos, downregulation of Ctgf expression is associated with p38 mitogen-activated protein kinase (MAPK) overactivation, whereas loss of function of Smad4 itself leads to downregulation of Ctgf expression. We also found that CTGF regulates its own expression via TGF-β signaling. Osr2-Cre; Smad4fl/fl mice exhibit a defect in cell proliferation similar to that of Tgfbr2 mutant mice, as well as cleft palate. We detected no alteration in bone morphogenetic protein (BMP) downstream targets in Smad4 mutant palates, suggesting that the reduction in cell proliferation is due to defective transduction of TGF-β signaling via decreased Ctgf expression. Significantly, an exogenous source of CTGF was able to rescue the cell proliferation defect in both Tgfbr2 and Smad4 mutant palates. Collectively, our data suggest that CTGF regulates proliferation as a mediator of the canonical pathway of TGF-β signaling during palatogenesis. PMID:23816882

  10. G-CSF maintains controlled neutrophil mobilization during acute inflammation by negatively regulating CXCR2 signaling

    PubMed Central

    Bajrami, Besnik; Zhu, Haiyan; Zhang, Yu C.

    2016-01-01

    Cytokine-induced neutrophil mobilization from the bone marrow to circulation is a critical event in acute inflammation, but how it is accurately controlled remains poorly understood. In this study, we report that CXCR2 ligands are responsible for rapid neutrophil mobilization during early-stage acute inflammation. Nevertheless, although serum CXCR2 ligand concentrations increased during inflammation, neutrophil mobilization slowed after an initial acute fast phase, suggesting a suppression of neutrophil response to CXCR2 ligands after the acute phase. We demonstrate that granulocyte colony-stimulating factor (G-CSF), usually considered a prototypical neutrophil-mobilizing cytokine, was expressed later in the acute inflammatory response and unexpectedly impeded CXCR2-induced neutrophil mobilization by negatively regulating CXCR2-mediated intracellular signaling. Blocking G-CSF in vivo paradoxically elevated peripheral blood neutrophil counts in mice injected intraperitoneally with Escherichia coli and sequestered large numbers of neutrophils in the lungs, leading to sterile pulmonary inflammation. In a lipopolysaccharide-induced acute lung injury model, the homeostatic imbalance caused by G-CSF blockade enhanced neutrophil accumulation, edema, and inflammation in the lungs and ultimately led to significant lung damage. Thus, physiologically produced G-CSF not only acts as a neutrophil mobilizer at the relatively late stage of acute inflammation, but also prevents exaggerated neutrophil mobilization and the associated inflammation-induced tissue damage during early-phase infection and inflammation. PMID:27551153

  11. Journal Impact Factor Shapes Scientists’ Reward Signal in the Prospect of Publication

    PubMed Central

    Paulus, Frieder Michel; Rademacher, Lena; Schäfer, Theo Alexander Jose; Müller-Pinzler, Laura; Krach, Sören

    2015-01-01

    The incentive structure of a scientist’s life is increasingly mimicking economic principles. While intensely criticized, the journal impact factor (JIF) has taken a role as the new currency for scientists. Successful goal-directed behavior in academia thus requires knowledge about the JIF. Using functional neuroimaging we examined how the JIF, as a powerful incentive in academia, has shaped the behavior of scientists and the reward signal in the striatum. We demonstrate that the reward signal in the nucleus accumbens increases with higher JIF during the anticipation of a publication and found a positive correlation with the personal publication record (pJIF) supporting the notion that scientists have incorporated the predominant reward principle of the scientific community in their reward system. The implications of this behavioral adaptation within the ecological niche of the scientist’s habitat remain unknown, but may also have effects which were not intended by the community. PMID:26555725

  12. Signaling by STATs

    PubMed Central

    Ivashkiv, Lionel B; Hu, Xiaoyu

    2004-01-01

    A variety of cytokines and growth factors use the Janus kinase (Jak)–STAT signaling pathway to transmit extracellular signals to the nucleus. STATs (signal transducers and activators of transcription) are latent cytoplasmic transcription factors. There are seven mammalian STATs and they have critical, nonredundant roles in mediating cellular transcriptional responses to cytokines. The physiological roles of STATs have been elucidated by analysis of mice rendered deficient in STAT genes. STAT activation is regulated and can be modulated in a positive or negative fashion; it can be reprogrammed to drive different cellular responses. Several auto-regulatory and signaling crosstalk mechanisms for regulating Jak–STAT signaling have been described. Understanding and manipulation of the function of STATs will help in the development of therapeutic strategies for diseases that are regulated by cytokines. PMID:15225360

  13. Signaling by STATs.

    PubMed

    Ivashkiv, Lionel B; Hu, Xiaoyu

    2004-01-01

    A variety of cytokines and growth factors use the Janus kinase (Jak)-STAT signaling pathway to transmit extracellular signals to the nucleus. STATs (signal transducers and activators of transcription) are latent cytoplasmic transcription factors. There are seven mammalian STATs and they have critical, nonredundant roles in mediating cellular transcriptional responses to cytokines. The physiological roles of STATs have been elucidated by analysis of mice rendered deficient in STAT genes. STAT activation is regulated and can be modulated in a positive or negative fashion; it can be reprogrammed to drive different cellular responses. Several auto-regulatory and signaling crosstalk mechanisms for regulating Jak-STAT signaling have been described. Understanding and manipulation of the function of STATs will help in the development of therapeutic strategies for diseases that are regulated by cytokines.

  14. The Hippo signaling functions through the Notch signaling to regulate intrahepatic bile duct development in mammals.

    PubMed

    Wu, Nan; Nguyen, Quy; Wan, Ying; Zhou, Tiaohao; Venter, Julie; Frampton, Gabriel A; DeMorrow, Sharon; Pan, Duojia; Meng, Fanyin; Glaser, Shannon; Alpini, Gianfranco; Bai, Haibo

    2017-07-01

    The Hippo signaling pathway and the Notch signaling pathway are evolutionary conserved signaling cascades that have important roles in embryonic development of many organs. In murine liver, disruption of either pathway impairs intrahepatic bile duct development. Recent studies suggested that the Notch signaling receptor Notch2 is a direct transcriptional target of the Hippo signaling pathway effector YAP, and the Notch signaling is a major mediator of the Hippo signaling in maintaining biliary cell characteristics in adult mice. However, it remains to be determined whether the Hippo signaling pathway functions through the Notch signaling in intrahepatic bile duct development. We found that loss of the Hippo signaling pathway tumor suppressor Nf2 resulted in increased expression levels of the Notch signaling pathway receptor Notch2 in cholangiocytes but not in hepatocytes. When knocking down Notch2 on the background of Nf2 deficiency in mouse livers, the excessive bile duct development induced by Nf2 deficiency was suppressed by heterozygous and homozygous deletion of Notch2 in a dose-dependent manner. These results implicated that Notch signaling is one of the downstream effectors of the Hippo signaling pathway in regulating intrahepatic bile duct development.

  15. The Hippo signaling functions through the Notch signaling to regulate intrahepatic bile duct development in mammals

    PubMed Central

    Wu, Nan; Nguyen, Quy; Wan, Ying; Zhou, Tiaohao; Venter, Julie; Frampton, Gabriel A; DeMorrow, Sharon; Pan, Duojia; Meng, Fanyin; Glaser, Shannon; Alpini, Gianfranco; Bai, Haibo

    2018-01-01

    The Hippo signaling pathway and the Notch signaling pathway are evolutionary conserved signaling cascades that have important roles in embryonic development of many organs. In murine liver, disruption of either pathway impairs intrahepatic bile duct development. Recent studies suggested that the Notch signaling receptor Notch2 is a direct transcriptional target of the Hippo signaling pathway effector YAP, and the Notch signaling is a major mediator of the Hippo signaling in maintaining biliary cell characteristics in adult mice. However, it remains to be determined whether the Hippo signaling pathway functions through the Notch signaling in intrahepatic bile duct development. We found that loss of the Hippo signaling pathway tumor suppressor Nf2 resulted in increased expression levels of the Notch signaling pathway receptor Notch2 in cholangiocytes but not in hepatocytes. When knocking down Notch2 on the background of Nf2 deficiency in mouse livers, the excessive bile duct development induced by Nf2 deficiency was suppressed by heterozygous and homozygous deletion of Notch2 in a dose-dependent manner. These results implicated that Notch signaling is one of the downstream effectors of the Hippo signaling pathway in regulating intrahepatic bile duct development. PMID:28581486

  16. Phase noise mitigation of QPSK signal utilizing phase-locked multiplexing of signal harmonics and amplitude saturation.

    PubMed

    Mohajerin-Ariaei, Amirhossein; Ziyadi, Morteza; Chitgarha, Mohammad Reza; Almaiman, Ahmed; Cao, Yinwen; Shamee, Bishara; Yang, Jeng-Yuan; Akasaka, Youichi; Sekiya, Motoyoshi; Takasaka, Shigehiro; Sugizaki, Ryuichi; Touch, Joseph D; Tur, Moshe; Langrock, Carsten; Fejer, Martin M; Willner, Alan E

    2015-07-15

    We demonstrate an all-optical phase noise mitigation scheme based on the generation, delay, and coherent summation of higher order signal harmonics. The signal, its third-order harmonic, and their corresponding delayed variant conjugates create a staircase phase-transfer function that quantizes the phase of quadrature-phase-shift-keying (QPSK) signal to mitigate phase noise. The signal and the harmonics are automatically phase-locked multiplexed, avoiding the need for phase-based feedback loop and injection locking to maintain coherency. The residual phase noise converts to amplitude noise in the quantizer stage, which is suppressed by parametric amplification in the saturation regime. Phase noise reduction of ∼40% and OSNR-gain of ∼3  dB at BER 10(-3) are experimentally demonstrated for 20- and 30-Gbaud QPSK input signals.

  17. Current and maintained health-enhancing physical activity in rheumatoid arthritis: a cross-sectional study.

    PubMed

    Demmelmaier, Ingrid; Bergman, Patrick; Nordgren, Birgitta; Jensen, Irene; Opava, Christina H

    2013-07-01

    To describe and identify the explanatory factors of variation in current and maintained health-enhancing physical activity (HEPA) in persons with rheumatoid arthritis (RA). In this cross-sectional study, current HEPA was assessed with the International Physical Activity Questionnaire and maintained HEPA with the Exercise Stage Assessment Instrument, the latter explicitly focusing on both aerobic physical activity and muscle strength training. Sociodemographic, disease-related, and psychosocial data were retrieved from the Swedish Rheumatology Quality (SRQ) registers and a postal questionnaire. The explained variations in the respective HEPA behaviors were analyzed with logistic regression. In all, 3,152 (58.5%) of 5,391 persons identified as eligible from the SRQ registers responded to the questionnaire. Current HEPA was reported by 69%, and maintained HEPA by 11% of the respondents. The most salient and consistent factors explaining variation in both current and maintained HEPA were self-efficacy, social support, and outcome expectations related to physical activity. To our knowledge, this is the first study exploring maintained physical activity in a large well-defined sample of persons with RA. Our results indicate that a minority perform maintained HEPA, including both aerobic physical activity and muscle strength training, and that psychosocial factors are the most salient and consistent in the explanation of HEPA variation. Copyright © 2013 by the American College of Rheumatology.

  18. CaM kinase signaling induces cardiac hypertrophy and activates the MEF2 transcription factor in vivo

    PubMed Central

    Passier, Robert; Zeng, Hong; Frey, Norbert; Naya, Francisco J.; Nicol, Rebekka L.; McKinsey, Timothy A.; Overbeek, Paul; Richardson, James A.; Grant, Stephen R.; Olson, Eric N.

    2000-01-01

    Hypertrophic growth is an adaptive response of the heart to diverse pathological stimuli and is characterized by cardiomyocyte enlargement, sarcomere assembly, and activation of a fetal program of cardiac gene expression. A variety of Ca2+-dependent signal transduction pathways have been implicated in cardiac hypertrophy, but whether these pathways are independent or interdependent and whether there is specificity among them are unclear. Previously, we showed that activation of the Ca2+/calmodulin-dependent protein phosphatase calcineurin or its target transcription factor NFAT3 was sufficient to evoke myocardial hypertrophy in vivo. Here, we show that activated Ca2+/calmodulin-dependent protein kinases-I and -IV (CaMKI and CaMKIV) also induce hypertrophic responses in cardiomyocytes in vitro and that CaMKIV overexpressing mice develop cardiac hypertrophy with increased left ventricular end-diastolic diameter and decreased fractional shortening. Crossing this transgenic line with mice expressing a constitutively activated form of NFAT3 revealed synergy between these signaling pathways. We further show that CaMKIV activates the transcription factor MEF2 through a posttranslational mechanism in the hypertrophic heart in vivo. Activated calcineurin is a less efficient activator of MEF2-dependent transcription, suggesting that the calcineurin/NFAT and CaMK/MEF2 pathways act in parallel. These findings identify MEF2 as a downstream target for CaMK signaling in the hypertrophic heart and suggest that the CaMK and calcineurin pathways preferentially target different transcription factors to induce cardiac hypertrophy. PMID:10811847

  19. Molecular neuro-oncology and development of targeted therapeutic strategies for brain tumors. Part 1: Growth factor and Ras signaling pathways.

    PubMed

    Newton, Herbert B

    2003-10-01

    Brain tumors are a diverse group of malignancies that remain refractory to conventional treatment approaches, including radiotherapy and cytotoxic chemotherapy. Molecular neuro-oncology has now begun to clarify the transformed phenotype of brain tumors and identify oncogenic pathways that may be amenable to targeted therapy. Growth factor signaling pathways are often upregulated in brain tumors and may contribute to oncogenesis through autocrine and paracrine mechanisms. Excessive growth factor receptor stimulation can also lead to overactivity of the Ras signaling pathway, which is frequently aberrant in brain tumors. Receptor tyrosine kinase inhibitors, antireceptor monoclonal antibodies and antisense oligonucleotides are targeted approaches under investigation as methods to regulate aberrant growth factor signaling pathways in brain tumors. Several receptor tyrosine kinase inhibitors, including imatinib mesylate (Gleevec), gefitinib (Iressa) and erlotinib (Tarceva), have entered clinical trials for high-grade glioma patients. Farnesyl transferase inhibitors, such as tipifarnib (Zarnestra), which impair processing of proRas and inhibit the Ras signaling pathway, have also entered clinical trials for patients with malignant gliomas. Further development of targeted therapies and evaluation of these new agents in clinical trials will be needed to improve survival and quality of life of patients with brain tumors.

  20. Wnt proteins are self-renewal factors for mammary stem cells and promote their long-term expansion in culture.

    PubMed

    Zeng, Yi Arial; Nusse, Roel

    2010-06-04

    Adult stem cells have the ability to self-renew and to generate specialized cells. Self-renewal is dependent on extrinsic niche factors but few of those signals have been identified. In addition, stem cells tend to differentiate in the absence of the proper signals and are therefore difficult to maintain in cell culture. The mammary gland provides an excellent system to study self-renewal signals, because the organ develops postnatally, arises from stem cells, and is readily generated from transplanted cells. We show here that adult mammary glands contain a Wnt-responsive cell population that is enriched for stem cells. In addition, stem cells mutant for the negative-feedback regulator Axin2 and therefore sensitized to Wnt signals have a competitive advantage in mammary gland reconstitution assays. In cell culture experiments, exposure to purified Wnt protein clonally expands mammary stem cells for many generations and maintains their ability to generate functional glands in transplantation assays. We conclude that Wnt proteins serve as rate-limiting self-renewal signals acting directly on mammary stem cells. Copyright 2010 Elsevier Inc. All rights reserved.

  1. Cell Proliferation and Epidermal Growth Factor Signaling in Non-small Cell Lung Adenocarcinoma Cell Lines Are Dependent on Rin1

    PubMed Central

    Tomshine, Jin C.; Severson, Sandra R.; Wigle, Dennis A.; Sun, Zhifu; Beleford, Daniah A. T.; Shridhar, Vijayalakshmi; Horazdovsky, Bruce F.

    2009-01-01

    Rin1 is a Rab5 guanine nucleotide exchange factor that plays an important role in Ras-activated endocytosis and growth factor receptor trafficking in fibroblasts. In this study, we show that Rin1 is expressed at high levels in a large number of non-small cell lung adenocarcinoma cell lines, including Hop62, H650, HCC4006, HCC827, EKVX, HCC2935, and A549. Rin1 depletion from A549 cells resulted in a decrease in cell proliferation that was correlated to a decrease in epidermal growth factor receptor (EGFR) signaling. Expression of wild type Rin1 but not the Rab5 guanine nucleotide exchange factor-deficient Rin1 (Rin1Δ) complemented the Rin1 depletion effects, and overexpression of Rin1Δ had a dominant negative effect on cell proliferation. Rin1 depletion stabilized the cell surface levels of EGFR, suggesting that internalization was necessary for robust signaling in A549 cells. In support of this conclusion, introduction of either dominant negative Rab5 or dominant negative dynamin decreased A549 proliferation and EGFR signaling. These data demonstrate that proper internalization and endocytic trafficking are critical for EGFR-mediated signaling in A549 cells and suggest that up-regulation of Rin1 in A549 cell lines may contribute to their proliferative nature. PMID:19570984

  2. The Drosophila mitochondrial translation elongation factor G1 contains a nuclear localization signal and inhibits growth and DPP signaling.

    PubMed

    Trivigno, Catherine; Haerry, Theodor E

    2011-02-25

    Mutations in the human mitochondrial elongation factor G1 (EF-G1) are recessive lethal and cause death shortly after birth. We have isolated mutations in iconoclast (ico), which encodes the highly conserved Drosophila orthologue of EF-G1. We find that EF-G1 is essential during fly development, but its function is not required in every tissue. In contrast to null mutations, missense mutations exhibit stronger, possibly neomorphic phenotypes that lead to premature death during embryogenesis. Our experiments show that EF-G1 contains a secondary C-terminal nuclear localization signal. Expression of missense mutant forms of EF-G1 can accumulate in the nucleus and cause growth and patterning defects and animal lethality. We find that transgenes that encode mutant human EF-G1 proteins can rescue ico mutants, indicating that the underlying problem of the human disease is not just the loss of enzymatic activity. Our results are consistent with a model where EF-G1 acts as a retrograde signal from mitochondria to the nucleus to slow down cell proliferation if mitochondrial energy output is low.

  3. The Drosophila Mitochondrial Translation Elongation Factor G1 Contains a Nuclear Localization Signal and Inhibits Growth and DPP Signaling

    PubMed Central

    Trivigno, Catherine; Haerry, Theodor E.

    2011-01-01

    Mutations in the human mitochondrial elongation factor G1 (EF-G1) are recessive lethal and cause death shortly after birth. We have isolated mutations in iconoclast (ico), which encodes the highly conserved Drosophila orthologue of EF-G1. We find that EF-G1 is essential during fly development, but its function is not required in every tissue. In contrast to null mutations, missense mutations exhibit stronger, possibly neomorphic phenotypes that lead to premature death during embryogenesis. Our experiments show that EF-G1 contains a secondary C-terminal nuclear localization signal. Expression of missense mutant forms of EF-G1 can accumulate in the nucleus and cause growth and patterning defects and animal lethality. We find that transgenes that encode mutant human EF-G1 proteins can rescue ico mutants, indicating that the underlying problem of the human disease is not just the loss of enzymatic activity. Our results are consistent with a model where EF-G1 acts as a retrograde signal from mitochondria to the nucleus to slow down cell proliferation if mitochondrial energy output is low. PMID:21364917

  4. Estrogen prevents bone loss through transforming growth factor β signaling in T cells

    PubMed Central

    Gao, Yuhao; Qian, Wei-Ping; Dark, Kimberly; Toraldo, Gianluca; Lin, Angela S. P.; Guldberg, Robert E.; Flavell, Richard A.; Weitzmann, M. Neale; Pacifici, Roberto

    2004-01-01

    Estrogen (E) deficiency leads to an expansion of the pool of tumor necrosis factor (TNF)-producing T cells through an IFN-γ-dependent pathway that results in increased levels of the osteoclastogenic cytokine TNF in the bone marrow. Disregulated IFN-γ production is instrumental for the bone loss induced by ovariectomy (ovx), but the responsible mechanism is unknown. We now show that mice with T cell-specific blockade of type β transforming growth factor (TGFβ) signaling are completely insensitive to the bone-sparing effect of E. This phenotype results from a failure of E to repress IFN-γ production, which, in turn, leads to increased T cell activation and T cell TNF production. Furthermore, ovx blunts TGFβ levels in the bone marrow, and overexpression of TGFβ in vivo prevents ovx-induced bone loss. These findings demonstrate that E prevents bone loss through a TGFβ-dependent mechanism, and that TGFβ signaling in T cells preserves bone homeostasis by blunting T cell activation. Thus, stimulation of TGFβ production in the bone marrow is a critical “upstream” mechanism by which E prevents bone loss, and enhancement of TGFβ levels in vivo may constitute a previously undescribed therapeutic approach for preventing bone loss. PMID:15531637

  5. Teaming Up for Trouble: Cancer Cells, Transforming Growth Factor-β1 Signaling and the Epigenetic Corruption of Stromal Naïve Fibroblasts.

    PubMed

    Lamprecht, Sergio; Sigal-Batikoff, Ina; Shany, Shraga; Abu-Freha, Naim; Ling, Eduard; Delinasios, George J; Moyal-Atias, Keren; Delinasios, John G; Fich, Alexander

    2018-02-27

    It is well recognized that cancer cells subvert the phenotype of stromal naïve fibroblasts and instruct the neighboring cells to sustain their growth agenda. The mechanisms underpinning the switch of fibroblasts to cancer-associated fibroblasts (CAFs) are the focus of intense investigation. One of the most significant hallmarks of the biological identity of CAFs is that their tumor-promoting phenotype is stably maintained during in vitro and ex vivo propagation without the continual interaction with the adjacent cancer cells. In this review, we discuss robust evidence showing that the master cytokine Transforming Growth Factor-β1 (TGFβ-1) is a prime mover in reshaping, via epigenetic switches, the phenotype of stromal fibroblasts to a durable state. We also examine, in detail, the pervasive involvement of TGFβ-1 signaling from both cancer cells and CAFs in fostering cancer development, taking colorectal cancer (CRC) as a paradigm of human neoplasia. Finally, we review the stroma-centric anticancer therapeutic approach focused on CAFs-the most abundant cell population of the tumor microenvironment (TME)-as target cells.

  6. A regulatory framework for shoot stem cell control integrating metabolic, transcriptional, and phytohormone signals.

    PubMed

    Schuster, Christoph; Gaillochet, Christophe; Medzihradszky, Anna; Busch, Wolfgang; Daum, Gabor; Krebs, Melanie; Kehle, Andreas; Lohmann, Jan U

    2014-02-24

    Plants continuously maintain pluripotent stem cells embedded in specialized tissues called meristems, which drive long-term growth and organogenesis. Stem cell fate in the shoot apical meristem (SAM) is controlled by the homeodomain transcription factor WUSCHEL (WUS) expressed in the niche adjacent to the stem cells. Here, we demonstrate that the bHLH transcription factor HECATE1 (HEC1) is a target of WUS and that it contributes to SAM function by promoting stem cell proliferation, while antagonizing niche cell activity. HEC1 represses the stem cell regulators WUS and CLAVATA3 (CLV3) and, like WUS, controls genes with functions in metabolism and hormone signaling. Among the targets shared by HEC1 and WUS are phytohormone response regulators, which we show to act as mobile signals in a universal feedback system. Thus, our work sheds light on the mechanisms guiding meristem function and suggests that the underlying regulatory system is far more complex than previously anticipated. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Rice bacterial blight pathogen Xanthomonas oryzae pv. oryzae produces multiple DSF-family signals in regulation of virulence factor production

    PubMed Central

    2010-01-01

    Background Xanthomonas oryzae pv. oryzae (Xoo) is the causal agent of rice bacterial blight disease. Xoo produces a range of virulence factors, including EPS, extracellular enzyme, iron-chelating siderophores, and type III-secretion dependent effectors, which are collectively essential for virulence. Genetic and genomics evidence suggest that Xoo might use the diffusible signal factor (DSF) type quorum sensing (QS) system to regulate the virulence factor production. However, little is known about the chemical structure of the DSF-like signal(s) produced by Xoo and the factors influencing the signal production. Results Xoo genome harbours an rpf cluster comprising rpfB, rpfF, rpfC and rpfG. The proteins encoded by these genes are highly homologous to their counterparts in X. campestris pv. campestris (Xcc), suggesting that Xcc and Xoo might use similar mechanisms for DSF biosynthesis and autoregulation. Consistent with in silico analysis, the rpfF mutant was DSF-deficient and the rpfC mutant produced about 25 times higher DSF-like activity than the wild type Xoo strain KACC10331. From the supernatants of rpfC mutant, we purified three compounds showing strong DSF-like activity. Mass spectrometry and NMR analysis revealed that two of them were the previously characterized DSF and BDSF; the third one was a novel unsaturated fatty acid with 2 double bonds and was designated as CDSF in this study. Further analysis showed that all the three DSF-family signals were synthesized via the enzyme RpfF encoded by Xoo2868. DSF and BDSF at a final concentration of 3 μM to the rpfF mutant could fully restore its extracellular xylanase activity and EPS production to the wild type level, but CDSF was less active than DSF and BDSF in induction of EPS and xylanase. DSF and CDSF shared a similar cell density-dependent production time course with the maximum production being detected at 42 h after inoculation, whereas the maximum production of BDSF was observed at 36 h after

  8. Xanthomonas campestris cell–cell signalling molecule DSF (diffusible signal factor) elicits innate immunity in plants and is suppressed by the exopolysaccharide xanthan

    PubMed Central

    Kakkar, Akanksha; Nizampatnam, Narasimha Rao; Kondreddy, Anil; Pradhan, Binod Bihari; Chatterjee, Subhadeep

    2015-01-01

    Several secreted and surface-associated conserved microbial molecules are recognized by the host to mount the defence response. One such evolutionarily well-conserved bacterial process is the production of cell–cell signalling molecules which regulate production of multiple virulence functions by a process known as quorum sensing. Here it is shown that a bacterial fatty acid cell–cell signalling molecule, DSF (diffusible signal factor), elicits innate immunity in plants. The DSF family of signalling molecules are highly conserved among many phytopathogenic bacteria belonging to the genus Xanthomonas as well as in opportunistic animal pathogens. Using Arabidopsis, Nicotiana benthamiana, and rice as model systems, it is shown that DSF induces a hypersensitivity reaction (HR)-like response, programmed cell death, the accumulation of autofluorescent compounds, hydrogen peroxide production, and the expression of the PATHOGENESIS-RELATED1 (PR-1) gene. Furthermore, production of the DSF signalling molecule in Pseudomonas syringae, a non-DSF-producing plant pathogen, induces the innate immune response in the N. benthamiana host plant and also affects pathogen growth. By pre- and co-inoculation of DSF, it was demonstrated that the DSF-induced plant defence reduces disease severity and pathogen growth in the host plant. In this study, it was further demonstrated that wild-type Xanthomonas campestris suppresses the DSF-induced innate immunity by secreting xanthan, the main component of extracellular polysaccharide. The results indicate that plants have evolved to recognize a widely conserved bacterial communication system and may have played a role in the co-evolution of host recognition of the pathogen and the communication machinery. PMID:26248667

  9. Phosphorylation of hepatocyte growth factor receptor and epidermal growth factor receptor of human hepatocytes can be maintained in a (3D) collagen sandwich culture system.

    PubMed

    Engl, Tobias; Boost, Kim A; Leckel, Kerstin; Beecken, Wolf-Dietrich; Jonas, Dietger; Oppermann, Elsie; Auth, Marcus K H; Schaudt, André; Bechstein, Wolf-Otto; Blaheta, Roman A

    2004-08-01

    In vitro culture models that employ human liver cells could be potent tools for predictive studies on drug toxicity and metabolism in the pharmaceutical industry. However, an adequate receptor responsiveness is necessary to allow intracellular signalling and metabolic activity. We tested the ability of three-dimensionally arranged human hepatocytes to respond to the growth factors hepatocyte growth factor (HGF) or epidermal growth factor (EGF). Isolated adult human hepatocytes were cultivated within a three-dimensional collagen gel (sandwich) or on a two-dimensional collagen matrix. Cells were treated with HGF or EGF and expression and phosphorylative activity of HGF receptors (HGFr, c-met) or EGF receptors (EGFr) were measured by flow cytometry and Western blot. Increasing HGFr and EGFr levels were detected in hepatocytes growing two-dimensionally. However, both receptors were not activated in presence of growth factors. In contrast, when hepatocytes were plated within a three-dimensional matrix, HGFr and EGFr levels remained constantly low. However, both receptors became strongly phosphorylated by soluble HGF or EGF. We conclude that cultivation of human hepatocytes in a three-dimensionally arranged in vitro system allows the maintenance of specific functional activities. The necessity of cell dimensionality for HGFr and EGFr function should be considered when an adequate in vitro system has to be introduced for drug testing.

  10. Signal detection by means of orthogonal decomposition

    NASA Astrophysics Data System (ADS)

    Hajdu, C. F.; Dabóczi, T.; Péceli, G.; Zamantzas, C.

    2018-03-01

    Matched filtering is a well-known method frequently used in digital signal processing to detect the presence of a pattern in a signal. In this paper, we suggest a time variant matched filter, which, unlike a regular matched filter, maintains a given alignment between the input signal and the template carrying the pattern, and can be realized recursively. We introduce a method to synchronize the two signals for presence detection, usable in case direct synchronization between the signal generator and the receiver is not possible or not practical. We then propose a way of realizing and extending the same filter by modifying a recursive spectral observer, which gives rise to orthogonal filter channels and also leads to another way to synchronize the two signals.

  11. High Resolution and Large Dynamic Range Resonant Pressure Sensor Based on Q-Factor Measurement

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C. (Inventor); Stell, Christopher B. (Inventor); Tang, Tony K. (Inventor); Vorperian, Vatche (Inventor); Wilcox, Jaroslava (Inventor); Shcheglov, Kirill (Inventor); Kaiser, William J. (Inventor)

    2000-01-01

    A pressure sensor has a high degree of accuracy over a wide range of pressures. Using a pressure sensor relying upon resonant oscillations to determine pressure, a driving circuit drives such a pressure sensor at resonance and tracks resonant frequency and amplitude shifts with changes in pressure. Pressure changes affect the Q-factor of the resonating portion of the pressure sensor. Such Q-factor changes are detected by the driving/sensing circuit which in turn tracks the changes in resonant frequency to maintain the pressure sensor at resonance. Changes in the Q-factor are reflected in changes of amplitude of the resonating pressure sensor. In response, upon sensing the changes in the amplitude, the driving circuit changes the force or strength of the electrostatic driving signal to maintain the resonator at constant amplitude. The amplitude of the driving signals become a direct measure of the changes in pressure as the operating characteristics of the resonator give rise to a linear response curve for the amplitude of the driving signal. Pressure change resolution is on the order of 10(exp -6) torr over a range spanning from 7,600 torr to 10(exp -6) torr. No temperature compensation for the pressure sensor of the present invention is foreseen. Power requirements for the pressure sensor are generally minimal due to the low-loss mechanical design of the resonating pressure sensor and the simple control electronics.

  12. Notch signaling and ageing.

    PubMed

    Polychronidou, Eleftheria; Vlachakis, Dimitrios; Vlamos, Panayiotis; Baumann, Marc; Kossida, Sophia

    2015-01-01

    Notch signaling is a master controller of the neural stem cell and neural development maintaining a significant role in the normal brain function. Notch genes are involved in embryogenesis, nervous system, and cardiovascular and endocrine function. On the other side, there are studies representing the involvement of Notch mutations in sporadic Alzheimer disease, other neurodegenerative diseases such as Down syndrome, Pick's and Prion's disease, and CADASIL. This manuscript attempts to present a holistic view of the positive or negative contribution of Notch signaling in the adult brain, and at the same time to present and promote the promising research fields of study.

  13. Polarization-discrimination technique to maximize the lidar signal-to-noise ratio for daylight operations.

    PubMed

    Hassebo, Yasser Y; Gross, Barry; Oo, Min; Moshary, Fred; Ahmed, Samir

    2006-08-01

    The impact and potential of a polarization-selection technique to reduce the sky background signal for linearly polarized monostatic elastic backscatter lidar measurements are examined. Taking advantage of naturally occurring polarization properties in scattered skylight, we devised a polarization-discrimination technique in which both the lidar transmitter and the receiver track and minimize detected sky background noise while maintaining maximum lidar signal throughput. Lidar elastic backscatter measurements, carried out continuously during daylight hours at 532 nm, show as much as a factor of square root 10 improvement in the signal-to-noise ratio (SNR) over conventional unpolarized schemes. For vertically pointing lidars, the largest improvements are limited to the early morning and late afternoon hours, while for lidars scanning azimuthally and in elevation at angles other than vertical, significant improvements are achievable over more extended time periods with the specific times and improvement factors depending on the specific angle between the lidar and the solar axes. The resulting diurnal variations in SNR improvement sometimes show an asymmetry with the solar angle that analysis indicates can be attributed to changes in observed relative humidity that modifies the underlying aerosol microphysics and observed optical depth.

  14. Polarization-discrimination technique to maximize the lidar signal-to-noise ratio for daylight operations

    NASA Astrophysics Data System (ADS)

    Hassebo, Yasser Y.; Gross, Barry; Oo, Min; Moshary, Fred; Ahmed, Samir

    2006-08-01

    The impact and potential of a polarization-selection technique to reduce the sky background signal for linearly polarized monostatic elastic backscatter lidar measurements are examined. Taking advantage of naturally occurring polarization properties in scattered skylight, we devised a polarization-discrimination technique in which both the lidar transmitter and the receiver track and minimize detected sky background noise while maintaining maximum lidar signal throughput. Lidar elastic backscatter measurements, carried out continuously during daylight hours at 532 nm, show as much as a factor of square root 10 improvement in the signal-to-noise ratio (SNR) over conventional unpolarized schemes. For vertically pointing lidars, the largest improvements are limited to the early morning and late afternoon hours, while for lidars scanning azimuthally and in elevation at angles other than vertical, significant improvements are achievable over more extended time periods with the specific times and improvement factors depending on the specific angle between the lidar and the solar axes. The resulting diurnal variations in SNR improvement sometimes show an asymmetry with the solar angle that analysis indicates can be attributed to changes in observed relative humidity that modifies the underlying aerosol microphysics and observed optical depth.

  15. Two MYB-related transcription factors play opposite roles in sugar signaling in Arabidopsis.

    PubMed

    Chen, Yi-Shih; Chao, Yi-Chi; Tseng, Tzu-Wei; Huang, Chun-Kai; Lo, Pei-Ching; Lu, Chung-An

    2017-02-01

    Sugar regulation of gene expression has profound effects at all stages of the plant life cycle. Although regulation at the transcriptional level is one of the most prominent mechanisms by which gene expression is regulated, only a few transcription factors have been identified and demonstrated to be involved in the regulation of sugar-regulated gene expression. OsMYBS1, an R1/2-type MYB transcription factor, has been demonstrated to be involved in sugar- and hormone-regulated α-amylase gene expression in rice. Arabidopsis contains two OsMYBS1 homologs. In the present study, we investigate MYBS1 and MYBS2 in sugar signaling in Arabidopsis. Our results indicate that MYBS1 and MYBS2 play opposite roles in regulating glucose and ABA signaling in Arabidopsis during seed germination and early seedling development. MYB proteins have been classified into four subfamilies: R2R3-MYB, R1/2-MYB, 3R-MYB, and 4R-MYB. An R1/2-type MYB transcription factor, OsMYBS1, has been demonstrated to be involved in sugar- and hormone-regulated α-amylase genes expression in rice. In this study, two genes homologous to OsMYBS1, MYBS1 and MYBS2, were investigated in Arabidopsis. Subcellular localization analysis showed that MYBS1 and MYBS2 were localized in the nucleus. Rice embryo transient expression assays indicated that both MYBS1 and MYBS2 could recognize the sugar response element, TA-box, in the promoter and induced promoter activity. mybs1 mutant exhibited hypersensitivity to glucose, whereas mybs2 seedlings were hyposensitive to it. MYBS1 and MYBS2 are involved in the control of glucose-responsive gene expression, as the mybs1 mutant displayed increased expression of a hexokinase gene (HXK1), chlorophyll a/b-binding protein gene (CAB1), ADP-glucose pyrophosphorylase gene (APL3), and chalcone synthase gene (CHS), whereas the mybs2 mutant exhibited decreased expression of these genes. mybs1 also showed an enhanced response to abscisic acid (ABA) in the seed germination and seedling

  16. Non-Smad signaling pathways.

    PubMed

    Mu, Yabing; Gudey, Shyam Kumar; Landström, Maréne

    2012-01-01

    Transforming growth factor-beta (TGFβ) is a key regulator of cell fate during embryogenesis and has also emerged as a potent driver of the epithelial-mesenchymal transition during tumor progression. TGFβ signals are transduced by transmembrane type I and type II serine/threonine kinase receptors (TβRI and TβRII, respectively). The activated TβR complex phosphorylates Smad2 and Smad3, converting them into transcriptional regulators that complex with Smad4. TGFβ also uses non-Smad signaling pathways such as the p38 and Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) pathways to convey its signals. Ubiquitin ligase tumor necrosis factor (TNF)-receptor-associated factor 6 (TRAF6) and TGFβ-associated kinase 1 (TAK1) have recently been shown to be crucial for the activation of the p38 and JNK MAPK pathways. Other TGFβ-induced non-Smad signaling pathways include the phosphoinositide 3-kinase-Akt-mTOR pathway, the small GTPases Rho, Rac, and Cdc42, and the Ras-Erk-MAPK pathway. Signals induced by TGFβ are tightly regulated and specified by post-translational modifications of the signaling components, since they dictate the subcellular localization, activity, and duration of the signal. In this review, we discuss recent findings in the field of TGFβ-induced responses by non-Smad signaling pathways.

  17. miR-24 and miR-122 Negatively Regulate the Transforming Growth Factor-β/Smad Signaling Pathway in Skeletal Muscle Fibrosis.

    PubMed

    Sun, Yaying; Wang, Hui; Li, Yan; Liu, Shaohua; Chen, Jiwu; Ying, Hao

    2018-06-01

    Fibrosis is common after skeletal muscle injury, undermining tissue regeneration and function. The mechanism underlying skeletal muscle fibrosis remains unveiled. Transforming growth factor-β/Smad signaling pathway is supposed to play a pivotal role. However, how microRNAs interact with transforming growth factor-β/Smad-related muscle fibrosis remains unclear. We showed that microRNA (miR)-24-3p and miR-122-5p declined in skeletal muscle fibrosis, which was a consequence of transforming growth factor-β. Upregulating Smad4 suppressed two microRNAs, whereas inhibiting Smad4 elevated microRNAs. Luciferase reporter assay and chromatin immunoprecipitation confirmed that Smad4 directly inhibited two microRNAs. On the other hand, overexpression of these two miRs retarded fibrotic process. We further identified that Smad2 was a direct target of miR-24-3p, whereas miR-122-5p targeted transforming growth factor-β receptor-II. Both targets were important participants in transforming growth factor-β/Smad signaling. Taken together, a positive feedback loop in transforming growth factor-β/Smad4 signaling pathway in skeletal muscle fibrosis was identified. Transforming growth factor-β/Smad axis could be downregulated by microRNAs. This effect, however, was suppressed by Smad4, the downstream of transforming growth factor-β. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  18. PCH1 integrates circadian and light-signaling pathways to control photoperiod-responsive growth in Arabidopsis

    PubMed Central

    Huang, He; Yoo, Chan Yul; Bindbeutel, Rebecca; Goldsworthy, Jessica; Tielking, Allison; Alvarez, Sophie; Naldrett, Michael J; Evans, Bradley S; Chen, Meng; Nusinow, Dmitri A

    2016-01-01

    Plants react to seasonal change in day length through altering physiology and development. Factors that function to harmonize growth with photoperiod are poorly understood. Here we characterize a new protein that associates with both circadian clock and photoreceptor components, named PHOTOPERIODIC CONTROL OF HYPOCOTYL1 (PCH1). pch1 seedlings have overly elongated hypocotyls specifically under short days while constitutive expression of PCH1 shortens hypocotyls independent of day length. PCH1 peaks at dusk, binds phytochrome B (phyB) in a red light-dependent manner, and co-localizes with phyB into photobodies. PCH1 is necessary and sufficient to promote the biogenesis of large photobodies to maintain an active phyB pool after light exposure, potentiating red-light signaling and prolonging memory of prior illumination. Manipulating PCH1 alters PHYTOCHROME INTERACTING FACTOR 4 levels and regulates light-responsive gene expression. Thus, PCH1 is a new factor that regulates photoperiod-responsive growth by integrating the clock with light perception pathways through modulating daily phyB-signaling. DOI: http://dx.doi.org/10.7554/eLife.13292.001 PMID:26839287

  19. Connective Tissue Disorders and Cardiovascular Complications: The indomitable role of Transforming Growth Factor-beta signaling

    PubMed Central

    Wheeler, Jason B.; Ikonomidis, John S.; Jones, Jeffrey A.

    2015-01-01

    Marfan Syndrome (MFS) and Loeys-Dietz Syndrome (LDS) represent heritable connective tissue disorders that cosegregate with a similar pattern of cardiovascular defects (thoracic aortic aneurysm, mitral valve prolapse/regurgitation, and aortic dilatation with regurgitation). This pattern of cardiovascular defects appears to be expressed along a spectrum of severity in many heritable connective tissue disorders and raises suspicion of a relationship between the normal development of connective tissues and the cardiovascular system. Given the evidence of increased transforming growth factor-beta (TGF-β) signaling in MFS and LDS, this signaling pathway may represent the common link in this relationship. To further explore this hypothetical link, this chapter will review the TGF-β signaling pathway, heritable connective tissue syndromes related to TGF-β receptor (TGFBR) mutations, and discuss the pathogenic contribution of TGF-β to these syndromes with a primary focus on the cardiovascular system. PMID:24443024

  20. Emerging Importance of Phytochemicals in Regulation of Stem Cells Fate via Signaling Pathways.

    PubMed

    Dadashpour, Mehdi; Pilehvar-Soltanahmadi, Younes; Zarghami, Nosratollah; Firouzi-Amandi, Akram; Pourhassan-Moghaddam, Mohammad; Nouri, Mohammad

    2017-11-01

    To reach ideal therapeutic potential of stem cells for regenerative medicine purposes, it is essential to retain their self-renewal and differentiation capacities. Currently, biological factors are extensively used for stemness maintaining and differentiation induction of stem cells. However, low stability, high cost, complicated production process, and risks associated with viral/endotoxin infection hamper the widespread use of biological factors in the stem cell biology. Moreover, regarding the modulation of several signaling cascades, which lead to a distinct fate, phytochemicals are preferable in the stem cells biology because of their efficiency. Considering the issues related to the application of biological factors and potential advantages of phytochemicals in stem cell engineering, there is a considerable increasing trend in studies associated with the application of novel alternative molecules in the stem cell biology. In support of this statement, we aimed to highlight the various effects of phytochemicals on signaling cascades involved in commitment of stem cells. Hence, in this review, the current trends in the phytochemicals-based modulation of stem cell fate have been addressed. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  1. Detection of single-molecule H2O2 signalling from epidermal growth factor receptor using fluorescent single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jin, Hong; Heller, Daniel A.; Kalbacova, Marie; Kim, Jong-Ho; Zhang, Jingqing; Boghossian, Ardemis A.; Maheshri, Narendra; Strano, Michael S.

    2010-04-01

    An emerging concept in cell signalling is the natural role of reactive oxygen species such as hydrogen peroxide (H2O2) as beneficial messengers in redox signalling pathways. The nature of H2O2 signalling is confounded, however, by difficulties in tracking it in living systems, both spatially and temporally, at low concentrations. Here, we develop an array of fluorescent single-walled carbon nanotubes that can selectively record, in real time, the discrete, stochastic quenching events that occur as H2O2 molecules are emitted from individual human epidermal carcinoma cells stimulated by epidermal growth factor. We show mathematically that such arrays can distinguish between molecules originating locally on the cell membrane from other contributions. We find that epidermal growth factor induces 2 nmol H2O2 locally over a period of 50 min. This platform promises a new approach to understanding the signalling of reactive oxygen species at the cellular level.

  2. Wright's Shifting Balance Theory and the Diversification of Aposematic Signals

    PubMed Central

    Chouteau, Mathieu; Angers, Bernard

    2012-01-01

    Despite accumulating evidence for selection within natural systems, the importance of random genetic drift opposing Wright's and Fisher's views of evolution continue to be a subject of controversy. The geographical diversification of aposematic signals appears to be a suitable system to assess the factors involved in the process of adaptation since both theories were independently proposed to explain this phenomenon. In the present study, the effects of drift and selection were assessed from population genetics and predation experiments on poison-dart frogs, Ranitomaya imitator, of Northern Peru. We specifically focus on the transient zone between two distinct aposematic signals. In contrast to regions where high predation maintains a monomorphic aposematic signal, the transient zones are characterized by lowered selection and a high phenotypic diversity. As a result, the diversification of phenotypes may occur via genetic drift without a significant loss of fitness. These new phenotypes may then colonize alternative habitats if successfully recognized and avoided by predators. This study highlights the interplay between drift and selection as determinant processes in the adaptive diversification of aposematic signals. Results are consistent with the expectations of the Wright's shifting balance theory and represent, to our knowledge, the first empirical demonstration of this highly contested theory in a natural system. PMID:22470509

  3. Initial Assessment, Surveillance, and Management of Blood Pressure in Patients Receiving Vascular Endothelial Growth Factor Signaling Pathway Inhibitors

    PubMed Central

    Bakris, George L.; Black, Henry R.; Chen, Helen X.; Durand, Jean-Bernard; Elliott, William J.; Ivy, S. Percy; Leier, Carl V.; Lindenfeld, JoAnn; Liu, Glenn; Remick, Scot C.; Steingart, Richard; Tang, W. H. Wilson

    2010-01-01

    Hypertension is a mechanism-based toxic effect of drugs that inhibit the vascular endothelial growth factor signaling pathway (VSP). Substantial evidence exists for managing hypertension as a chronic condition, but there are few prospectively collected data on managing acute hypertension caused by VSP inhibitors. The Investigational Drug Steering Committee of the National Cancer Institute convened an interdisciplinary cardiovascular toxicities expert panel to evaluate this problem, to make recommendations to the Cancer Therapy Evaluation Program on further study, and to structure an approach for safe management by treating physicians. The panel reviewed: the published literature on blood pressure (BP), hypertension, and specific VSP inhibitors; abstracts from major meetings; shared experience with the development of VSP inhibitors; and established principles of hypertension care. The panel generated a consensus report including the recommendations on clinical concerns summarized here. To support the greatest possible number of patients to receive VSP inhibitors safely and effectively, the panel had four recommendations: 1) conduct and document a formal risk assessment for potential cardiovascular complications, 2) recognize that preexisting hypertension will be common in cancer patients and should be identified and addressed before initiation of VSP inhibitor therapy, 3) actively monitor BP throughout treatment with more frequent assessments during the first cycle of treatment, and 4) manage BP with a goal of less than 140/90 mmHg for most patients (and to lower, prespecified goals in patients with specific preexisting cardiovascular risk factors). Proper agent selection, dosing, and scheduling of follow-up should enable maintaining VSP inhibition while avoiding the complications associated with excessive or prolonged elevation in BP. PMID:20351338

  4. Interferon regulatory factor 4 attenuates Notch signaling to suppress the development of chronic lymphocytic leukemia

    PubMed Central

    Shukla, Vipul; Shukla, Ashima; Joshi, Shantaram S.

    2016-01-01

    Molecular pathogenesis of Chronic Lymphocytic Leukemia (CLL) is not fully elucidated. Genome wide association studies have linked Interferon Regulatory Factor 4 (IRF4) to the development of CLL. We recently established a causal relationship between low levels of IRF4 and development of CLL. However, the molecular mechanism through which IRF4 suppresses CLL development remains unclear. Deregulation of Notch signaling pathway has been identified as one of the most recurrent molecular anomalies in the pathogenesis of CLL. Yet, the role of Notch signaling as well as its regulation during CLL development remains poorly understood. Previously, we demonstrated that IRF4 deficient mice expressing immunoglobulin heavy chain Vh11 (IRF4−/−Vh11) developed spontaneous CLL with complete penetrance. In this study, we show that elevated Notch2 expression and the resulting hyperactivation of Notch signaling are common features of IRF4−/−Vh11 CLL cells. Our studies further reveal that Notch signaling is indispensable for CLL development in the IRF4−/−Vh11 mice. Moreover, we identify E3 ubiquitin ligase Nedd4, which targets Notch for degradation, as a direct target of IRF4 in CLL cells and their precursors. Collectively, our studies provide the first in vivo evidence for an essential role of Notch signaling in the development of CLL and establish IRF4 as a critical regulator of Notch signaling during CLL development. PMID:27232759

  5. Notch signaling mediates granulocyte-macrophage colony-stimulating factor priming-induced transendothelial migration of human eosinophils.

    PubMed

    Liu, L Y; Wang, H; Xenakis, J J; Spencer, L A

    2015-07-01

    Priming with cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF) enhances eosinophil migration and exacerbates the excessive accumulation of eosinophils within the bronchial mucosa of asthmatics. However, mechanisms that drive GM-CSF priming are incompletely understood. Notch signaling is an evolutionarily conserved pathway that regulates cellular processes, including migration, by integrating exogenous and cell-intrinsic cues. This study investigates the hypothesis that the priming-induced enhanced migration of human eosinophils requires the Notch signaling pathway. Using pan Notch inhibitors and newly developed human antibodies that specifically neutralize Notch receptor 1 activation, we investigated a role for Notch signaling in GM-CSF-primed transmigration of human blood eosinophils in vitro and in the airway accumulation of mouse eosinophils in vivo. Notch receptor 1 was constitutively active in freshly isolated human blood eosinophils, and inhibition of Notch signaling or specific blockade of Notch receptor 1 activation during GM-CSF priming impaired priming-enhanced eosinophil transendothelial migration in vitro. Inclusion of Notch signaling inhibitors during priming was associated with diminished ERK phosphorylation, and ERK-MAPK activation was required for GM-CSF priming-induced transmigration. In vivo in mice, eosinophil accumulation within allergic airways was impaired following systemic treatment with Notch inhibitor, or adoptive transfer of eosinophils treated ex vivo with Notch inhibitor. These data identify Notch signaling as an intrinsic pathway central to GM-CSF priming-induced eosinophil tissue migration. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. ATAR, a novel tumor necrosis factor receptor family member, signals through TRAF2 and TRAF5.

    PubMed

    Hsu, H; Solovyev, I; Colombero, A; Elliott, R; Kelley, M; Boyle, W J

    1997-05-23

    Members of tumor necrosis factor receptor (TNFR) family signal largely through interactions with death domain proteins and TRAF proteins. Here we report the identification of a novel TNFR family member ATAR. Human and mouse ATAR contain 283 and 276 amino acids, respectively, making them the shortest known members of the TNFR superfamily. The receptor is expressed mainly in spleen, thymus, bone marrow, lung, and small intestine. The intracellular domains of human and mouse ATAR share only 25% identity, yet both interact with TRAF5 and TRAF2. This TRAF interaction domain resides at the C-terminal 20 amino acids. Like most other TRAF-interacting receptors, overexpression of ATAR activates the transcription factor NF-kappaB. Co-expression of ATAR with TRAF5, but not TRAF2, results in synergistic activation of NF-kappaB, suggesting potentially different roles for TRAF2 and TRAF5 in post-receptor signaling.

  7. Characterization of Phytochrome Interacting Factors from the Moss Physcomitrella patens Illustrates Conservation of Phytochrome Signaling Modules in Land Plants

    PubMed Central

    Xu, Tengfei; Paik, Inyup; Hanke, Sebastian; Keim, Sarah; Hermann, Helen-Maria; Wolf, Luise; Becker, Claude

    2017-01-01

    Across the plant kingdom, phytochrome (PHY) photoreceptors play an important role during adaptive and developmental responses to light. In Arabidopsis thaliana, light-activated PHYs accumulate in the nucleus, where they regulate downstream signaling components, such as phytochrome interacting factors (PIFs). PIFs are transcription factors that act as repressors of photomorphogenesis; their inhibition by PHYs leads to substantial changes in gene expression. The nuclear function of PHYs, however, has so far been investigated in only a few non-seed plants. Here, we identified putative target genes of PHY signaling in the moss Physcomitrella patens and found light-regulated genes that are putative orthologs of PIF-controlled genes in Arabidopsis. Phylogenetic analyses revealed that an ancestral PIF-like gene was already present in streptophyte algae, i.e., before the water-to-land transition of plants. The PIF homologs in the genome of P. patens resemble Arabidopsis PIFs in their protein domain structure, molecular properties, and physiological effects, albeit with notable differences in the motif-dependent PHY interaction. Our results suggest that P. patens PIFs are involved in PHY signaling. The PHY-PIF signaling node that relays light signals to target genes has been largely conserved during land plant evolution, with evidence of lineage-specific diversification. PMID:28123107

  8. Nuclear factor I-C reciprocally regulates adipocyte and osteoblast differentiation via control of canonical Wnt signaling.

    PubMed

    Zhou, Jie; Wang, Shan; Qi, Qi; Yang, Xiaoyue; Zhu, Endong; Yuan, Hairui; Li, Xuemei; Liu, Ying; Li, Xiaoxia; Wang, Baoli

    2017-05-01

    Nuclear factor I-C (NFIC) has recently been identified as an important player in osteogenesis and bone homeostasis in vivo However, the molecular mechanisms involved have yet to be defined. In the current study, Nfic expression was altered in primary marrow stromal cells and established progenitor lines after adipogenic and osteogenic treatment. Overexpression of Nfic in stromal cells ST2, mesenchymal cells C3H10T1/2, and primary marrow stromal cells inhibited adipogenic differentiation, whereas it promoted osteogenic differentiation. Conversely, silencing of endogenous Nfic in the cell lines enhanced adipogenic differentiation, whereas it blocked osteogenic differentiation. Mechanism investigations revealed that Nfic overexpression promoted nuclear translocation of β-catenin and increased nuclear protein levels of β-catenin and transcription factor 7-like 2 (TCF7L2). Promoter studies and the chromatin immunoprecipitation (ChIP) assay revealed that NFIC directly binds to the promoter of low-density lipoprotein receptor-related protein 5 (Lrp5) and thereafter transactivates the promoter. Finally, inactivation of canonical Wnt signaling in ST2 attenuated the inhibition of adipogenic differentiation and stimulation of osteogenic differentiation by NFIC. Our study suggests that NFIC balances adipogenic and osteogenic differentiation from progenitor cells through controlling canonical Wnt signaling and highlights the potential of NFIC as a target for new therapies to control metabolic disorders like osteoporosis and obesity.-Zhou, J., Wang, S., Qi, Q., Yang, X., Zhu, E., Yuan, H., Li, X., Liu, Y., Li, X., Wang, B. Nuclear factor I-C reciprocally regulates adipocyte and osteoblast differentiation via control of canonical Wnt signaling. © FASEB.

  9. Blockade of vascular endothelial growth factor receptor and epidermal growth factor receptor signaling for therapy of metastatic human pancreatic cancer.

    PubMed

    Baker, Cheryl H; Solorzano, Carmen C; Fidler, Isaiah J

    2002-04-01

    We determined whether concurrent blockage of vascular endothelial growth factor (VEGF) receptor and epidermal growth factor (EGF) receptor signaling by two novel tyrosine kinase inhibitors, PTK 787 and PKI 166, respectively, can inhibit angiogenesis and, hence, the growth and metastasis of human pancreatic carcinoma in nude mice. Highly metastatic human pancreatic carcinoma L3.6pl cells were injected into the pancreas of nude mice. Seven days later, groups of mice began receiving oral doses of PTK 787 and PKI 166 three times weekly. Some groups of mice also received i.p. injections of gemcitabine twice a week. The mice were necropsied when the control mice became moribund. Treatment with PTK 787 and PKI 166, with gemcitabine alone, or with the combination of PTK 787, PKI 166, and gemcitabine produced 69, 50, and 97% reduction in the volume of pancreatic tumors, respectively. Administration of protein tyrosine kinase inhibitors and gemcitabine also significantly decreased the incidence of lymph node and liver metastasis. The therapeutic efficacy directly correlated with a decrease in circulating proangiogenic molecules (VEGF, interleukin-8), a decrease in microvessel density, a decrease in proliferating cell nuclear antigen staining, and an increase in apoptosis of tumor cells and endothelial cells. Therapies produced by combining gemcitabine with either PKI 166 or PTK 787 were similar to those produced by combining gemcitabine with both PKI 166 and PTK 787. These results suggest that blockade of either epidermal growth factor receptor or VEGF receptor signaling combined with chemotherapy provides an effective approach to the therapy of pancreatic cancer.

  10. Unity power factor switching regulator

    NASA Technical Reports Server (NTRS)

    Rippel, Wally E. (Inventor)

    1983-01-01

    A single or multiphase boost chopper regulator operating with unity power factor, for use such as to charge a battery is comprised of a power section for converting single or multiphase line energy into recharge energy including a rectifier (10), one inductor (L.sub.1) and one chopper (Q.sub.1) for each chopper phase for presenting a load (battery) with a current output, and duty cycle control means (16) for each chopper to control the average inductor current over each period of the chopper, and a sensing and control section including means (20) for sensing at least one load parameter, means (22) for producing a current command signal as a function of said parameter, means (26) for producing a feedback signal as a function of said current command signal and the average rectifier voltage output over each period of the chopper, means (28) for sensing current through said inductor, means (18) for comparing said feedback signal with said sensed current to produce, in response to a difference, a control signal applied to the duty cycle control means, whereby the average inductor current is proportionate to the average rectifier voltage output over each period of the chopper, and instantaneous line current is thereby maintained proportionate to the instantaneous line voltage, thus achieving a unity power factor. The boost chopper is comprised of a plurality of converters connected in parallel and operated in staggered phase. For optimal harmonic suppression, the duty cycles of the switching converters are evenly spaced, and by negative coupling between pairs 180.degree. out-of-phase, peak currents through the switches can be reduced while reducing the inductor size and mass.

  11. Wnt/β-catenin and LIF-Stat3 signaling pathways converge on Sp5 to promote mouse embryonic stem cell self-renewal.

    PubMed

    Ye, Shoudong; Zhang, Dongming; Cheng, Fei; Wilson, Daniel; Mackay, Jeffrey; He, Kan; Ban, Qian; Lv, Feng; Huang, Saifei; Liu, Dahai; Ying, Qi-Long

    2016-01-15

    Activation of leukemia inhibitor factor (LIF)-Stat3 or Wnt/β-catenin signaling promotes mouse embryonic stem cell (mESC) self-renewal. A myriad of downstream targets have been identified in the individual signal pathways, but their common targets remain largely elusive. In this study, we found that the LIF-Stat3 and Wnt/β-catenin signaling pathways converge on Sp5 to promote mESC self-renewal. Forced Sp5 expression can reproduce partial effects of Wnt/β-catenin signaling but mimics most features of LIF-Stat3 signaling to maintain undifferentiated mESCs. Moreover, Sp5 is able to convert mouse epiblast stem cells into a naïve pluripotent state. Thus, Sp5 is an important component of the regulatory network governing mESC naïve pluripotency. © 2016. Published by The Company of Biologists Ltd.

  12. 17-Beta-estradiol inhibits transforming growth factor-beta signaling and function in breast cancer cells via activation of extracellular signal-regulated kinase through the G protein-coupled receptor 30.

    PubMed

    Kleuser, Burkhard; Malek, Daniela; Gust, Ronald; Pertz, Heinz H; Potteck, Henrik

    2008-12-01

    Breast cancer development and breast cancer progression involves the deregulation of growth factors leading to uncontrolled cellular proliferation, invasion and metastasis. Transforming growth factor (TGF)-beta plays a crucial role in breast cancer because it has the potential to act as either a tumor suppressor or a pro-oncogenic chemokine. A cross-communication between the TGF-beta signaling network and estrogens has been postulated, which is important for breast tumorigenesis. Here, we provide evidence that inhibition of TGF-beta signaling is associated with a rapid estrogen-dependent nongenomic action. Moreover, we were able to demonstrate that estrogens disrupt the TGF-beta signaling network as well as TGF-beta functions in breast cancer cells via the G protein-coupled receptor 30 (GPR30). Silencing of GPR30 in MCF-7 cells completely reduced the ability of 17-beta-estradiol (E2) to inhibit the TGF-beta pathway. Likewise, in GPR30-deficient MDA-MB-231 breast cancer cells, E2 achieved the ability to suppress TGF-beta signaling only after transfection with GPR30-encoding plasmids. It is most interesting that the antiestrogen fulvestrant (ICI 182,780), which possesses agonistic activity at the GPR30, also diminished TGF-beta signaling. Further experiments attempted to characterize the molecular mechanism by which activated GPR30 inhibits the TGF-beta pathway. Our results indicate that GPR30 induces the stimulation of the mitogen-activated protein kinases (MAPKs), which interferes with the activation of Smad proteins. Inhibition of MAPK activity prevented the ability of E2 from suppressing TGF-beta signaling. These findings are of great clinical relevance, because down-regulation of TGF-beta signaling is associated with the development of breast cancer resistance in response to antiestrogens.

  13. Xanthomonas campestris cell-cell signalling molecule DSF (diffusible signal factor) elicits innate immunity in plants and is suppressed by the exopolysaccharide xanthan.

    PubMed

    Kakkar, Akanksha; Nizampatnam, Narasimha Rao; Kondreddy, Anil; Pradhan, Binod Bihari; Chatterjee, Subhadeep

    2015-11-01

    Several secreted and surface-associated conserved microbial molecules are recognized by the host to mount the defence response. One such evolutionarily well-conserved bacterial process is the production of cell-cell signalling molecules which regulate production of multiple virulence functions by a process known as quorum sensing. Here it is shown that a bacterial fatty acid cell-cell signalling molecule, DSF (diffusible signal factor), elicits innate immunity in plants. The DSF family of signalling molecules are highly conserved among many phytopathogenic bacteria belonging to the genus Xanthomonas as well as in opportunistic animal pathogens. Using Arabidopsis, Nicotiana benthamiana, and rice as model systems, it is shown that DSF induces a hypersensitivity reaction (HR)-like response, programmed cell death, the accumulation of autofluorescent compounds, hydrogen peroxide production, and the expression of the PATHOGENESIS-RELATED1 (PR-1) gene. Furthermore, production of the DSF signalling molecule in Pseudomonas syringae, a non-DSF-producing plant pathogen, induces the innate immune response in the N. benthamiana host plant and also affects pathogen growth. By pre- and co-inoculation of DSF, it was demonstrated that the DSF-induced plant defence reduces disease severity and pathogen growth in the host plant. In this study, it was further demonstrated that wild-type Xanthomonas campestris suppresses the DSF-induced innate immunity by secreting xanthan, the main component of extracellular polysaccharide. The results indicate that plants have evolved to recognize a widely conserved bacterial communication system and may have played a role in the co-evolution of host recognition of the pathogen and the communication machinery. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  14. Phytochrome B and REVEILLE1/2-mediated signalling controls seed dormancy and germination in Arabidopsis.

    PubMed

    Jiang, Zhimin; Xu, Gang; Jing, Yanjun; Tang, Weijiang; Lin, Rongcheng

    2016-08-10

    Seeds maintain a dormant state to withstand adverse conditions and germinate when conditions become favourable to give rise to a new generation of flowering plants. Seed dormancy and germination are tightly controlled by internal and external signals. Although phytochrome photoreceptors are proposed to regulate primary seed dormancy, the underlying molecular mechanism remains elusive. Here we show that the REVEILLE1 (RVE1) and RVE2 transcription factors promote primary seed dormancy and repress red/far-red-light-reversible germination downstream of phytochrome B (phyB) in Arabidopsis thaliana. RVE1 and RVE2 expression is downregulated after imbibition and by phyB. RVE1 directly binds to the promoter of GIBBERELLIN 3-OXIDASE 2, inhibits its transcription and thus suppresses the biosynthesis of bioactive gibberellins. In addition, DELAY OF GERMINATION 1 also acts downstream of phyB. This study identifies a signalling pathway that integrates environmental light input with internal factors to control both seed dormancy and germination.

  15. Q-factor improvement of degenerate four-wave-mixing regenerators for ASE degraded signals

    NASA Astrophysics Data System (ADS)

    Lu, Hang; Wu, Bao-jian; Geng, Yong; Zhou, Xing-yu; Sun, Fan

    2017-11-01

    All-optical regenerators can be used to suppress amplified spontaneous emission (ASE) noise introduced by cascaded erbium doped fiber amplifiers (EDFAs) in optical fiber communication systems and lead to the improvement of optical receiver sensitivity. By introducing the Q-factor transfer function (QTF), we evaluate the Q-factor performance of degenerate four-wave mixing (DFWM) regenerators with clock pump and reveal the differences between the optimal input powers determined from the static and dynamic power tranfer function (PTF) and the QTF curves. Our simulation shows that the clock-pump regnerator is capable of improving the Q-facor and receiver sensitivity for 40 Gbit/s ASE-degraded return-to-zero on-off keying (RZ-OOK) signal by 2.58 dB and 4.2 dB, respectively.

  16. Growth Factor FGF2 Cooperates with Interleukin-17 to Repair Intestinal Epithelial Damage.

    PubMed

    Song, Xinyang; Dai, Dai; He, Xiao; Zhu, Shu; Yao, Yikun; Gao, Hanchao; Wang, Jingjing; Qu, Fangfang; Qiu, Ju; Wang, Honglin; Li, Xiaoxia; Shen, Nan; Qian, Youcun

    2015-09-15

    The intestinal epithelial barrier plays a critical role in the mucosal immunity. However, it remains largely unknown how the epithelial barrier is maintained after damage. Here we show that growth factor FGF2 synergized with interleukin-17 (IL-17) to induce genes for repairing of damaged epithelium. FGF2 or IL-17 deficiency resulted in impaired epithelial proliferation, increased pro-inflammatory microbiota outgrowth, and consequently worse pathology in a DSS-induced colitis model. The dysregulated microbiota in the model induced transforming growth factor beta 1 (TGFβ1) expression, which in turn induced FGF2 expression mainly in regulatory T cells. Act1, an essential adaptor in IL-17 signaling, suppressed FGF2-induced ERK activation through binding to adaptor molecule GRB2 to interfere with its association with guanine nucleotide exchange factor SOS1. Act1 preferentially bound to IL-17 receptor complex, releasing its suppressive effect on FGF2 signaling. Thus, microbiota-driven FGF2 and IL-17 cooperate to repair the damaged intestinal epithelium through Act1-mediated direct signaling cross-talk. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. CONNECTIVE TISSUE GROWTH FACTOR IS A TARGET OF NOTCH SIGNALING IN CELLS OF THE OSTEOBLASTIC LINEAGE

    PubMed Central

    Canalis, Ernesto; Zanotti, Stefano; Smerdel-Ramoya, Anna

    2014-01-01

    Connective tissue growth factor (Ctgf) or CCN2 is a protein synthesized by osteoblasts necessary for skeletal homeostasis, although its overexpression inhibits osteogenic signals and bone formation. Ctgf is induced by bone morphogenetic proteins, transforming growth factor β and Wnt; and in the present studies, we explored whether Notch regulated Ctgf expression in osteoblasts. We employed RosaNotch mice, where the Notch intracellular domain (NICD) is expressed following the excision of a STOP cassette, placed between the Rosa26 promoter and NICD. Notch was activated by transduction of adenoviral vectors expressing Cre recombinase (Ad-CMV-Cre). Notch induced Ctgf mRNA levels in a time dependent manner and increased Ctgf heterogeneous nuclear RNA. Notch also destabilized Ctgf mRNA shortening its half-life from 13 h to 3 h. The effect of Notch on Ctgf expression was lost following Rbpjκ downregulation, demonstrating that it was mediated by Notch canonical signaling. However, downregulation of the classic Notch target genes Hes1, Hey1 and Hey2 did not modify the effect of Notch on Ctgf expression. Wild type osteoblasts exposed to immobilized Delta-like 1 displayed enhanced Notch signaling and increased Ctgf expression. In addition to the effects of Notch in vitro, Notch induced Ctgf in vivo, and calvariae and femurs from RosaNotch mice mated with transgenics expressing the Cre recombinase in cells of the osteoblastic lineage exhibited increased expression of Ctgf. In conclusion, Ctgf is a target of Notch canonical signaling in osteoblasts, and may act in concert with Notch to regulate skeletal homeostasis. PMID:24792956

  18. Integration of growth factor signals at the c-fos serum response element.

    PubMed

    Price, M A; Hill, C; Treisman, R

    1996-04-29

    A transcription factor ternary complex composed of serum response factor (SRF) and a second factor, ternary complex factor (TCF), mediates the response of the c-fos Serum Response Element to growth factors and mitogens. In NIH3T3 fibroblasts, TCF binding is required for transcriptional activation by the SRE in response to activation of the Ras-Raf-ERK pathway. We compared the properties of three members of the TCF family, Elk-1, SAP-1 and SAP-2 (ERP/NET). Although all the proteins contain sequences required for ternary complex formation with SRF, only Elk-1 and SAP-1 appear to interact with the c-fos SRE efficiently in vivo. Each TCF contains a C-terminal activation domain capable of transcriptional activation in response to activation of the Ras-Raf-ERK pathway, and this is dependent on the integrity of S/T-P motifs conserved between all the TCF family members. In contrast, activation of the SRE by whole serum and the mitogenic phospholipid LPA requires SRF binding alone. Constitutively activated members of the Rho subfamily of Ras-like GTPases are also capable of inducing activation of the SRE in the absence of TCF; unlike activated Ras itself, these proteins do not activate the TCFs in NIH3T3 cells. At the SRE, SRF- and TCF-linked signalling pathways act synergistically to potentiate transcription.

  19. Oncogenic fusion proteins adopt the insulin-like growth factor signaling pathway.

    PubMed

    Werner, Haim; Meisel-Sharon, Shilhav; Bruchim, Ilan

    2018-02-19

    The insulin-like growth factor-1 receptor (IGF1R) has been identified as a potent anti-apoptotic, pro-survival tyrosine kinase-containing receptor. Overexpression of the IGF1R gene constitutes a typical feature of most human cancers. Consistent with these biological roles, cells expressing high levels of IGF1R are expected not to die, a quintessential feature of cancer cells. Tumor specific chromosomal translocations that disrupt the architecture of transcription factors are a common theme in carcinogenesis. Increasing evidence gathered over the past fifteen years demonstrate that this type of genomic rearrangements is common not only among pediatric and hematological malignancies, as classically thought, but may also provide a molecular and cytogenetic foundation for an ever-increasing portion of adult epithelial tumors. In this review article we provide evidence that the mechanism of action of oncogenic fusion proteins associated with both pediatric and adult malignancies involves transactivation of the IGF1R gene, with ensuing increases in IGF1R levels and ligand-mediated receptor phosphorylation. Disrupted transcription factors adopt the IGF1R signaling pathway and elicit their oncogenic activities via activation of this critical regulatory network. Combined targeting of oncogenic fusion proteins along with the IGF1R may constitute a promising therapeutic approach.

  20. E3 Ubiquitin Ligase VHL Regulates Hypoxia-Inducible Factor-1α to Maintain Regulatory T Cell Stability and Suppressive Capacity.

    PubMed

    Lee, Jee H; Elly, Chris; Park, Yoon; Liu, Yun-Cai

    2015-06-16

    Foxp3(+) regulatory T (Treg) cells play a critical role in immune homeostasis; however, the mechanisms to maintain their function remain unclear. Here, we report that the E3 ubiquitin ligase VHL is essential for Treg cell function. Mice with Foxp3-restricted VHL deletion displayed massive inflammation associated with excessive Treg cell interferon-γ (IFN-γ) production. VHL-deficient Treg cells failed to prevent colitis induction, but converted into Th1-like effector T cells. VHL intrinsically orchestrated such conversion under both steady and inflammatory conditions followed by Foxp3 downregulation, which was reversed by IFN-γ deficiency. Augmented hypoxia-inducible factor 1α (HIF-1α)-induced glycolytic reprogramming was required for IFN-γ production. Furthermore, HIF-1α bound directly to the Ifng promoter. HIF-1α knockdown or knockout could reverse the increased IFN-γ by VHL-deficient Treg cells and restore their suppressive function in vivo. These findings indicate that regulation of HIF-1α pathway by VHL is crucial to maintain the stability and suppressive function of Foxp3(+) T cells. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. The corepressor CtBP interacts with Evi-1 to repress transforming growth factor beta signaling.

    PubMed

    Izutsu, K; Kurokawa, M; Imai, Y; Maki, K; Mitani, K; Hirai, H

    2001-05-01

    Evi-1 is a zinc finger nuclear protein whose inappropriate expression leads to leukemic transformation of hematopoietic cells in mice and humans. This was previously shown to block the antiproliferative effect of transforming growth factor beta (TGF-beta). Evi-1 represses TGF-beta signaling by direct interaction with Smad3 through its first zinc finger motif. Here, it is demonstrated that Evi-1 represses Smad-induced transcription by recruiting C-terminal binding protein (CtBP) as a corepressor. Evi-1 associates with CtBP1 through one of the consensus binding motifs, and this association is required for efficient inhibition of TGF-beta signaling. A specific inhibitor for histone deacetylase (HDAc) alleviates Evi-1-mediated repression of TGF-beta signaling, suggesting that HDAc is involved in the transcriptional repression by Evi-1. This identifies a novel function of Evi-1 as a member of corepressor complexes and suggests that aberrant recruitment of corepressors is one of the mechanisms for Evi-1-induced leukemogenesis.

  2. Signal Factors Secreted by 2D and Spheroid Mesenchymal Stem Cells and by Cocultures of Mesenchymal Stem Cells Derived Microvesicles and Retinal Photoreceptor Neurons

    PubMed Central

    Mao, Mao; Zhou, Liang

    2017-01-01

    We aim to identify levels of signal factors secreted by MSCs cultured in 2D monolayers (2D-MSCs), spheroids (spheroids MSCs), and cocultures of microvesicles (MVs) derived from 2D-MSCs or spheroid MSCs and retinal photoreceptor neurons. We seeded 2D-MSCs, spheroid MSCs, and cells derived from spheroids MSCs at equal numbers. MVs isolated from all 3 culture conditions were incubated with 661W cells. Levels of 51 signal factors in conditioned medium from those cultured conditions were quantified with bead-based assay. We found that IL-8, IL-6, and GROα were the top three most abundant signal factors. Moreover, compared to 2D-MSCs, levels of 11 cytokines and IL-2Rα were significantly increased in conditioned medium from spheroid MSCs. Finally, to test if enhanced expression of these factors reflects altered immunomodulating activities, we assessed the effect of 2D-MSC-MVs and 3D-MSC-MVs on CD14+ cell chemoattraction. Compared to 2D-MSC-MVs, 3D-MSC-MVs significantly decreased the chemotactic index of CD14+ cells. Our results suggest that spheroid culture conditions improve the ability of MSCs to selectively secrete signal factors. Moreover, 3D-MSC-MVs also possessed an enhanced capability to promote signal factors secretion compared to 2D-MSC-MVs and may possess enhanced immunomodulating activities and might be a better regenerative therapy for retinal degenerative diseases. PMID:28194184

  3. Interferometric sensor based on the polarization-maintaining fibers

    NASA Astrophysics Data System (ADS)

    Cubik, Jakub; Kepak, Stanislav; Doricak, Jan; Vašinek, Vladimir; Liner, Andrej; Papes, Martin

    2012-01-01

    The interferometers composed of optical fibers are due to its high sensitivity capable of to measure various influences affecting the fiber. These influences may be bending or different sorts of fiber deformations, vibration, temperature, etc. In this case the vibration is the measured quantity, which is evaluated by analyzing the interference fringes representing changes in the fiber. Was used a Mach-Zehnder interferometer composed of the polarization maintaining elements. The polarization maintaining elements were used because of high sensitivity to polarization state inside the interferometer. The light was splitted into the two optical paths, where the first one is the reference fiber and it is separated from the actual phenomenon, and the second one is measuring fiber, which is directly exposed to vibration transmission from the underlying surface. The light source was narrowband DFB laser serating at a wavelength of 1550nm and as a detector an InGaAs PIN photodiode were used in this measurement. The electrical signal from the photodiode was amplified and fed into the measuring card. On the incoming signal the FFT was applied, which performs the transformation into the frequency domain and the results were further evaluated by software. We were evaluating the characteristic frequencies and their amplitude ratios. The frequency responses are unique for a given phenomenon, thus it is possible to identify recurring events by the characteristic frequencies and their amplitude ratios. The frequency range was limited by the properties of the used speaker, by the frequency characteristics of the filter in the amplifier and used resonant element. For the experiment evaluation the repeated impact of the various spherical objects on the surface board was performed and measured. The stability of amplitude and frequency and also the frequency range was verified in this measurement.

  4. Insulin/Insulin-like growth factor signaling controls non-Dauer developmental speed in the nematode Caenorhabditis elegans.

    PubMed

    Ruaud, Anne-Françoise; Katic, Iskra; Bessereau, Jean-Louis

    2011-01-01

    Identified as a major pathway controlling entry in the facultative dauer diapause stage, the DAF-2/Insulin receptor (InsR) signaling acts in multiple developmental and physiological regulation events in Caenorhabditis elegans. Here we identified a role of the insulin-like pathway in controlling developmental speed during the C. elegans second larval stage. This role relies on the canonical DAF-16/FOXO-dependent branch of the insulin-like signaling and is largely independent of dauer formation. Our studies provide further evidence for broad conservation of insulin/insulin-like growth factor (IGF) functions in developmental speed control.

  5. Alleviation of ischaemia-reperfusion injury by endogenous estrogen involves maintaining Bcl-2 expression via the ERα signalling pathway.

    PubMed

    Zhang, Zeng-Li; Qin, Pei; Liu, Yuhong; Zhang, Li-Xia; Guo, Hang; Deng, You-Liang; Yizhao-Liu; Hou, Yu-Shu; Wang, Li-Yang; Miao, Yi; Ma, Yu-Long; Hou, Wu-Gang

    2017-04-15

    The neuroprotective effects of estrogen against cerebral ischaemia have been confirmed by multiple basic and clinical studies. However, most of these studies used exogenous estrogen administered via different injection methods, and the neuroprotective effects of endogenous estrogen produced by ovaries during different phases of estrous cycle and the underlying mechanisms involved have rarely been explored. In this study, we first identified the stage of estrous cycle via vaginal smears and then measured serum estradiol levels at each phase via radioimmunoassay. We found that the estradiol level was highest in the proestrous and lowest in the diestrous. However, ovariectomy or treatment with the aromatase inhibitor letrozole significantly decreased estradiol levels compared to that of rats in diestrous. Western blotting showed that ovariectomy or letrozole treatment significantly decreased ERα and Bcl-2 protein expression and dramatically increased Bax protein expression compared with the rats in diestrous or proestrous. Rats also underwent 2h of ischaemia via middle cerebral artery occlusion followed by a 24-h reperfusion. Ovariectomy or letrozole treatment significantly decreased the neurological scores and the number of intact neurons detected via Nissl staining and dramatically increased the infarct volume detected via TTC staining and the extent of apoptosis detected via TUNEL staining and Western blotting for cleaved-caspase 3 protein expression. These results demonstrate that endogenous estrogen alleviates ischaemia-reperfusion injury by maintaining Bcl-2 expression via ERα signalling pathway and highlight the neuroprotective effects of endogenous estrogen during different stages of the estrous cycle, providing preliminary information on the underlying mechanism of this process. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Molecular pathways of platelet factor 4/CXCL4 signaling.

    PubMed

    Kasper, Brigitte; Petersen, Frank

    2011-01-01

    The platelet-derived chemokine CXCL4 takes a specific and unique position within the family of chemotactic cytokines. Today, much attention is directed to CXCL4's capacity to inhibit angiogenesis and to promote innate immune responses, which makes this chemokine an interesting tool and target for potential intervention in tumor growth and inflammation. However, such attempts demand a comprehensive knowledge on the molecular mechanisms and pathways underlying the corresponding cellular functions. At least two structurally different receptors, CXCR3-B and a chondroitin sulfate proteoglycan, are capable of binding CXCL4 and to induce a specific intracellular signaling machinery. While signaling mediated by CXCR3-B involves Gs proteins, elevated cAMP levels, and p38 MAP kinase, signaling via proteoglycans appears to be more complicated and varies strongly between the cell types analyzed. In CXCL4-activated neutrophils and monocytes, tyrosine kinases of the Src family and Syk as well as monomeric GTPases and members of the MAP kinase family have been identified as essential intracellular signals. Most intriguingly, signaling does not proceed in a linear sequence of events but in a repeated activation of certain transducing elements like Rac2 or sphingosine kinase 1. Depending on the downstream targets, such biphasic kinetics either leads to a redundant and prolonged activation of a single pathway or to a timely separated initiation of disparate signals and functions. Results of the studies reviewed here help to understand the molecular basis of CXCL4's functional diversity and provide insights into integrated signaling processes in general. Copyright © 2011 Elsevier GmbH. All rights reserved.

  7. Homodimeric cross-over structure of the human granulocyte colony-stimulating factor (GCSF) receptor signaling complex

    PubMed Central

    Tamada, Taro; Honjo, Eijiro; Maeda, Yoshitake; Okamoto, Tomoyuki; Ishibashi, Matsujiro; Tokunaga, Masao; Kuroki, Ryota

    2006-01-01

    A crystal structure of the signaling complex between human granulocyte colony-stimulating factor (GCSF) and a ligand binding region of GCSF receptor (GCSF-R), has been determined to 2.8 Å resolution. The GCSF:GCSF-R complex formed a 2:2 stoichiometry by means of a cross-over interaction between the Ig-like domains of GCSF-R and GCSF. The conformation of the complex is quite different from that between human GCSF and the cytokine receptor homologous domain of mouse GCSF-R, but similar to that of the IL-6/gp130 signaling complex. The Ig-like domain cross-over structure necessary for GCSF-R activation is consistent with previously reported thermodynamic and mutational analyses. PMID:16492764

  8. Transcription factor AP-2γ induces early Cdx2 expression and represses HIPPO signaling to specify the trophectoderm lineage

    PubMed Central

    Cao, Zubing; Carey, Timothy S.; Ganguly, Avishek; Wilson, Catherine A.; Paul, Soumen; Knott, Jason G.

    2015-01-01

    Cell fate decisions are fundamental to the development of multicellular organisms. In mammals the first cell fate decision involves segregation of the pluripotent inner cell mass and the trophectoderm, a process regulated by cell polarity proteins, HIPPO signaling and lineage-specific transcription factors such as CDX2. However, the regulatory mechanisms that operate upstream to specify the trophectoderm lineage have not been established. Here we report that transcription factor AP-2γ (TFAP2C) functions as a novel upstream regulator of Cdx2 expression and position-dependent HIPPO signaling in mice. Loss- and gain-of-function studies and promoter analysis revealed that TFAP2C binding to an intronic enhancer is required for activation of Cdx2 expression during early development. During the 8-cell to morula transition TFAP2C potentiates cell polarity to suppress HIPPO signaling in the outside blastomeres. TFAP2C depletion triggered downregulation of PARD6B, loss of apical cell polarity, disorganization of F-actin, and activation of HIPPO signaling in the outside blastomeres. Rescue experiments using Pard6b mRNA restored cell polarity but only partially corrected position-dependent HIPPO signaling, suggesting that TFAP2C negatively regulates HIPPO signaling via multiple pathways. Several genes involved in regulation of the actin cytoskeleton (including Rock1, Rock2) were downregulated in TFAP2C-depleted embryos. Inhibition of ROCK1 and ROCK2 activity during the 8-cell to morula transition phenocopied TFAP2C knockdown, triggering a loss of position-dependent HIPPO signaling and decrease in Cdx2 expression. Altogether, these results demonstrate that TFAP2C facilitates trophectoderm lineage specification by functioning as a key regulator of Cdx2 transcription, cell polarity and position-dependent HIPPO signaling. PMID:25858457

  9. Transcription factor AP-2γ induces early Cdx2 expression and represses HIPPO signaling to specify the trophectoderm lineage.

    PubMed

    Cao, Zubing; Carey, Timothy S; Ganguly, Avishek; Wilson, Catherine A; Paul, Soumen; Knott, Jason G

    2015-05-01

    Cell fate decisions are fundamental to the development of multicellular organisms. In mammals the first cell fate decision involves segregation of the pluripotent inner cell mass and the trophectoderm, a process regulated by cell polarity proteins, HIPPO signaling and lineage-specific transcription factors such as CDX2. However, the regulatory mechanisms that operate upstream to specify the trophectoderm lineage have not been established. Here we report that transcription factor AP-2γ (TFAP2C) functions as a novel upstream regulator of Cdx2 expression and position-dependent HIPPO signaling in mice. Loss- and gain-of-function studies and promoter analysis revealed that TFAP2C binding to an intronic enhancer is required for activation of Cdx2 expression during early development. During the 8-cell to morula transition TFAP2C potentiates cell polarity to suppress HIPPO signaling in the outside blastomeres. TFAP2C depletion triggered downregulation of PARD6B, loss of apical cell polarity, disorganization of F-actin, and activation of HIPPO signaling in the outside blastomeres. Rescue experiments using Pard6b mRNA restored cell polarity but only partially corrected position-dependent HIPPO signaling, suggesting that TFAP2C negatively regulates HIPPO signaling via multiple pathways. Several genes involved in regulation of the actin cytoskeleton (including Rock1, Rock2) were downregulated in TFAP2C-depleted embryos. Inhibition of ROCK1 and ROCK2 activity during the 8-cell to morula transition phenocopied TFAP2C knockdown, triggering a loss of position-dependent HIPPO signaling and decrease in Cdx2 expression. Altogether, these results demonstrate that TFAP2C facilitates trophectoderm lineage specification by functioning as a key regulator of Cdx2 transcription, cell polarity and position-dependent HIPPO signaling. © 2015. Published by The Company of Biologists Ltd.

  10. Regulation of long-term repopulating hematopoietic stem cells by EPCR/PAR1 signaling

    PubMed Central

    Gur-Cohen, Shiri; Kollet, Orit; Graf, Claudine; Esmon, Charles T.; Ruf, Wolfram; Lapidot, Tsvee

    2016-01-01

    The common developmental origin of endothelial and hematopoietic cells is manifested by coexpression of several cell surface receptors. Adult murine bone marrow (BM) long-term repopulating hematopoietic stem cells (LT-HSCs), endowed with the highest repopulation and self-renewal potential, express endothelial protein C receptor (EPCR), which is used as a marker to isolate them. EPCR/PAR1 signaling in endothelial cells has anticoagulant and anti-inflammatory roles, while thrombin/PAR1 signaling induces coagulation and inflammation. Recent studies define two new PAR1-mediated signaling cascades that regulate EPCR+ LT-HSC BM retention and egress. EPCR/PAR1 signaling facilitates LT-HSC BM repopulation, retention, survival, and chemotherapy resistance by restricting nitric oxide (NO) production, maintaining NOlow LT-HSC BM retention with increased VLA4 expression, affinity, and adhesion. Conversely, acute stress and clinical mobilization upregulate thrombin generation and activate different PAR1 signaling which overcomes BM EPCR+ LT-HSC retention, inducing their recruitment to the bloodstream. Thrombin/PAR1 signaling induces NO generation, TACE-mediated EPCR shedding, and upregulation of CXCR4 and PAR1, leading to CXCL12-mediated stem and progenitor cell mobilization. This review discusses new roles for factors traditionally viewed as coagulation related, which independently act in the BM to regulate PAR1 signaling in bone- and blood-forming progenitor cells, navigating their fate by controlling NO production. PMID:26928241

  11. Quiescent gastric stem cells maintain the adult Drosophila stomach.

    PubMed

    Strand, Marie; Micchelli, Craig A

    2011-10-25

    The adult Drosophila copper cell region or "stomach" is a highly acidic compartment of the midgut with pH < 3. In this region, a specialized group of acid-secreting cells similar to mammalian gastric parietal cells has been identified by a unique ultrastructure and by copper-metallothionein fluorescence. However, the homeostatic mechanism maintaining the acid-secreting "copper cells" of the adult midgut has not been examined. Here, we combine cell lineage tracing and genetic analysis to investigate the mechanism by which the gastric epithelium is maintained. Our investigation shows that a molecularly identifiable population of multipotent, self-renewing gastric stem cells (GSSCs) produces the acid-secreting copper cells, interstitial cells, and enteroendocrine cells of the stomach. Our assays demonstrate that GSSCs are largely quiescent but can be induced to regenerate the gastric epithelium in response to environmental challenge. Finally, genetic analysis reveals that adult GSSC maintenance depends on Wnt signaling. Characterization of the GSSC lineage in Drosophila, with striking similarities to mammals, will advance the study of both homeostatic and pathogenic processes in the stomach.

  12. The Angiocrine Factor Rspondin3 Is a Key Determinant of Liver Zonation.

    PubMed

    Rocha, Ana Sofia; Vidal, Valerie; Mertz, Marjolijn; Kendall, Timothy J; Charlet, Aurelie; Okamoto, Hitoshi; Schedl, Andreas

    2015-12-01

    Liver zonation, the spatial separation of different metabolic pathways along the liver sinusoids, is fundamental for proper functioning of this organ, and its disruption can lead to the development of metabolic disorders such as hyperammonemia. Metabolic zonation involves the induction of β-catenin signaling around the central veins, but how this patterned activity is established and maintained is unclear. Here, we show that the signaling molecule Rspondin3 is specifically expressed within the endothelial compartment of the central vein. Conditional deletion of Rspo3 in mice disrupts activation of central fate, demonstrating its crucial role in determining and maintaining β-catenin-dependent zonation. Moreover, ectopic expression of Rspo1, a close family member of Rspo3, induces the expression of pericentral markers, demonstrating Rspondins to be sufficient to imprint a more central fate. Thus, Rspo3 is a key angiocrine factor that controls metabolic zonation of liver hepatocytes. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  13. Activin-A, transforming growth factor-beta, and myostatin signaling pathway in experimental dilated cardiomyopathy.

    PubMed

    Mahmoudabady, Maryam; Mathieu, Myrielle; Dewachter, Laurence; Hadad, Ielham; Ray, Lynn; Jespers, Pascale; Brimioulle, Serge; Naeije, Robert; McEntee, Kathleen

    2008-10-01

    The pathogenic mechanisms of dilated cardiomyopathy are still uncertain. A number of cytokines and growth factors participate in the remodeling process of the disease. We investigated the cardiac myostatin, transforming growth factor (TGF)beta, and activin-A/Smad growth inhibitory signaling pathway in experimental dilated cardiomyopathy. Transvenous endomyocardial biopsies of the interventricular septum were taken weekly in 15 beagle dogs during the development of heart failure (HF) induced by rapid pacing over a period of 7 weeks. Genes involved in the myostatin-TGFbeta-activin-A/Smad signaling pathway and the cardiac hypertrophic process were quantified by real-time quantitative polymerase chain reaction. Left ventricular volume, function, and mass were evaluated by echocardiography. Overpacing was associated with increased left ventricular volumes and decreased ejection fraction, whereas the left ventricular mass remained unchanged. TGFbeta was increased in moderate HF. Activin-A mRNA expression was 4-fold higher in overt congestive HF than at baseline. A 2-fold decrease of activin type II receptors and activin receptor interacting protein 2 gene expressions were observed, as well as a transient decrease of follistatin. Activin type I receptors, activin receptor interacting protein 1, follistatin-related gene, and myostatin remained unchanged. The inhibitory Smad 7, a negative feedback loop regulator of the Smad pathway, was overexpressed in severe HF. Gene expression of the cyclin-dependent kinase inhibitor p21, a direct target gene of the Smad pathway, was 8-fold up-regulated in HF, whereas cyclin D1 was down-regulated. We conclude that tachycardia-induced dilated cardiomyopathy is characterized by gene overexpression of the TGFbeta-activin-A/Smad signaling pathway and their target gene p21 and by the absence of ventricular hypertrophy.

  14. An improved method based on wavelet coefficient correlation to filter noise in Doppler ultrasound blood flow signals

    NASA Astrophysics Data System (ADS)

    Wan, Renzhi; Zu, Yunxiao; Shao, Lin

    2018-04-01

    The blood echo signal maintained through Medical ultrasound Doppler devices would always include vascular wall pulsation signal .The traditional method to de-noise wall signal is using high-pass filter, which will also remove the lowfrequency part of the blood flow signal. Some scholars put forward a method based on region selective reduction, which at first estimates of the wall pulsation signals and then removes the wall signal from the mixed signal. Apparently, this method uses the correlation between wavelet coefficients to distinguish blood signal from wall signal, but in fact it is a kind of wavelet threshold de-noising method, whose effect is not so much ideal. In order to maintain a better effect, this paper proposes an improved method based on wavelet coefficient correlation to separate blood signal and wall signal, and simulates the algorithm by computer to verify its validity.

  15. Synergistic apoptosis in head and neck squamous cell carcinoma cells by co-inhibition of insulin-like growth factor-1 receptor signaling and compensatory signaling pathways.

    PubMed

    Axelrod, Mark J; Mendez, Rolando E; Khalil, Ashraf; Leimgruber, Stephanie S; Sharlow, Elizabeth R; Capaldo, Brian; Conaway, Mark; Gioeli, Daniel G; Weber, Michael J; Jameson, Mark J

    2015-12-01

    In head and neck squamous cell carcinoma (HNSCC), resistance to single-agent targeted therapy may be overcome by co-targeting of compensatory signaling pathways. A targeted drug screen with 120 combinations was used on 9 HNSCC cell lines. Multiple novel drug combinations demonstrated synergistic growth inhibition. Combining the insulin-like growth factor-1 receptor (IGF-1R) inhibitor, BMS754807, with either the human epidermal growth factor receptor (HER)-family inhibitor, BMS599626, or the Src-family kinase inhibitor, dasatinib, resulted in substantial synergy and growth inhibition. Depending on the cell line, these combinations induced synergistic or additive apoptosis; when synergistic apoptosis was observed, AKT phosphorylation was inhibited to a greater extent than either drug alone. Conversely, when additive apoptosis occurred, AKT phosphorylation was not reduced by the drug combination. Combined IGF-1R/HER family and IGF-1R/Src family inhibition may have therapeutic potential in HNSCC. AKT may be a node of convergence between IGF-1R signaling and pathways that compensate for IGF-1R inhibition. © 2015 Wiley Periodicals, Inc.

  16. The Krüppel-like factor 2 and Krüppel-like factor 4 genes interact to maintain endothelial integrity in mouse embryonic vasculogenesis

    PubMed Central

    2013-01-01

    Background Krüppel-like Factor 2 (KLF2) plays an important role in vessel maturation during embryonic development. In adult mice, KLF2 regulates expression of the tight junction protein occludin, which may allow KLF2 to maintain vascular integrity. Adult tamoxifen-inducible Krüppel-like Factor 4 (KLF4) knockout mice have thickened arterial intima following vascular injury. The role of KLF4, and the possible overlapping functions of KLF2 and KLF4, in the developing vasculature are not well-studied. Results Endothelial breaks are observed in a major vessel, the primary head vein (PHV), in KLF2-/-KLF4-/- embryos at E9.5. KLF2-/-KLF4-/- embryos die by E10.5, which is earlier than either single knockout. Gross hemorrhaging of multiple vessels may be the cause of death. E9.5 KLF2-/-KLF4+/- embryos do not exhibit gross hemorrhaging, but cross-sections display disruptions of the endothelial cell layer of the PHV, and these embryos generally also die by E10.5. Electron micrographs confirm that there are gaps in the PHV endothelial layer in E9.5 KLF2-/-KLF4-/- embryos, and show that the endothelial cells are abnormally bulbous compared to KLF2-/- and wild-type (WT). The amount of endothelial Nitric Oxide Synthase (eNOS) mRNA, which encodes an endothelial regulator, is reduced by 10-fold in E9.5 KLF2-/-KLF4-/- compared to KLF2-/- and WT embryos. VEGFR2, an eNOS inducer, and occludin, a tight junction protein, gene expression are also reduced in E9.5 KLF2-/-KLF4-/- compared to KLF2-/- and WT embryos. Conclusions This study begins to define the roles of KLF2 and KLF4 in the embryonic development of blood vessels. It indicates that the two genes interact to maintain an intact endothelial layer. KLF2 and KLF4 positively regulate the eNOS, VEGFR2 and occludin genes. Down-regulation of these genes in KLF2-/-KLF4-/- embryos may result in the observed loss of vascular integrity. PMID:24261709

  17. Vascular endothelial growth factor c/vascular endothelial growth factor receptor 3 signaling regulates chemokine gradients and lymphocyte migration from tissues to lymphatics.

    PubMed

    Iwami, Daiki; Brinkman, C Colin; Bromberg, Jonathan S

    2015-04-01

    Circulation of leukocytes via blood, tissue and lymph is integral to adaptive immunity. Afferent lymphatics form CCL21 gradients to guide dendritic cells and T cells to lymphatics and then to draining lymph nodes (dLN). Vascular endothelial growth factor C and vascular endothelial growth factor receptor 3 (VEGFR-3) are the major lymphatic growth factor and receptor. We hypothesized these molecules also regulate chemokine gradients and lymphatic migration. CD4 T cells were injected into the foot pad or ear pinnae, and migration to afferent lymphatics and dLN quantified by flow cytometry or whole mount immunohistochemistry. Vascular endothelial growth factor receptor 3 or its signaling or downstream actions were modified with blocking monoclonal antibodies (mAbs) or other reagents. Anti-VEGFR-3 prevented migration of CD4 T cells into lymphatic lumen and significantly decreased the number that migrated to dLN. Anti-VEGFR-3 abolished CCL21 gradients around lymphatics, although CCL21 production was not inhibited. Heparan sulfate (HS), critical to establish CCL21 gradients, was down-regulated around lymphatics by anti-VEGFR-3 and this was dependent on heparanase-mediated degradation. Moreover, a Phosphoinositide 3-kinase (PI3K)α inhibitor disrupted HS and CCL21 gradients, whereas a PI3K activator prevented the effects of anti-VEGFR-3. During contact hypersensitivity, VEGFR-3, CCL21, and HS expression were all attenuated, and anti-heparanase or PI3K activator reversed these effects. Vascular endothelial growth factor C/VEGFR-3 signaling through PI3Kα regulates the activity of heparanase, which modifies HS and CCL21 gradients around lymphatics. The functional and physical linkages of these molecules regulate lymphatic migration from tissues to dLN. These represent new therapeutic targets to influence immunity and inflammation.

  18. Effects of heparin-binding epidermal growth factor-like growth factor on cell repopulation and signal transduction in periodontal ligament cells after scratch wounding in vitro.

    PubMed

    Lee, J S; Kim, J M; Hong, E K; Kim, S-O; Yoo, Y-J; Cha, J-H

    2009-02-01

    A growing amount of attention has been placed on periodontal regeneration and wound healing for periodontal therapy. This study was conducted in an effort to determine the effects of heparin-binding epidermal growth factor-like growth factor on cell repopulation and signal transduction in periodontal ligament cells after scratch wounding in vitro. Human periodontal ligament cells were acquired from explant tissue of human healthy periodontal ligament. After the wounding of periodontal ligament cells, the change in expression of heparin-binding epidermal growth factor-like growth factor and epidermal growth factor receptors 1-4 mRNA was assessed. The effects of heparin-binding epidermal growth factor-like growth factor on periodontal ligament cell proliferation and repopulation were assessed in vitro via the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and by photographing the injuries, respectively. Extracellular signal-regulated kinase (Erk)1/2, p38 and Akt phosphorylation was characterized via western blotting. Scratch wounding resulted in a significant up-regulation of heparin-binding epidermal growth factor-like growth factor mRNA expression, whereas wounding had no effect on the expression levels of epidermal growth factor receptors 1-4. Interestingly, no expression of epidermal growth factor receptors 2 and 4 was detectable prior to or after wounding. Heparin-binding epidermal growth factor-like growth factor treatment promoted the proliferation and repopulation of periodontal ligament cells. The scratch wounding also stimulated the phosphorylation of Erk1/2 and p38, but not of Akt, in periodontal ligament cells, and heparin-binding epidermal growth factor-like growth factor treatment applied after wounding amplified and extended the activations of Erk1/2 and p38, but not of Akt. Furthermore, Erk1/2 inhibition blocked the process of cell repopulation induced by heparin-binding epidermal growth factor-like growth factor, whereas the

  19. Androgen receptor signaling and mutations in prostate cancer

    PubMed Central

    Koochekpour, Shahriar

    2010-01-01

    Normal and neoplastic growth of the prostate gland are dependent on androgen receptor (AR) expression and function. Androgenic activation of the AR, in association with its coregulatory factors, is the classical pathway that leads to transcriptional activity of AR target genes. Alternatively, cytoplasmic signaling crosstalk of AR by growth factors, neurotrophic peptides, cytokines or nonandrogenic hormones may have important roles in prostate carcinogenesis and in metastatic or androgen-independent (AI) progression of the disease. In addition, cross-modulation by various nuclear transcription factors acting through basal transcriptional machinery could positively or negatively affect the AR or AR target genes expression and activity. Androgen ablation leads to an initial favorable response in a significant number of patients; however, almost invariably patients relapse with an aggressive form of the disease known as castration-resistant or hormone-refractory prostate cancer (PCa). Understanding critical molecular events that lead PCa cells to resist androgen-deprivation therapy is essential in developing successful treatments for hormone-refractory disease. In a significant number of hormone-refractory patients, the AR is overexpressed, mutated or genomically amplified. These genetic alterations maintain an active presence for a highly sensitive AR, which is responsive to androgens, antiandrogens or nonandrogenic hormones and collectively confer a selective growth advantage to PCa cells. This review provides a brief synopsis of the AR structure, AR coregulators, posttranslational modifications of AR, duality of AR function in prostate epithelial and stromal cells, AR-dependent signaling, genetic changes in the form of somatic and germline mutations and their known functional significance in PCa cells and tissues. PMID:20711217

  20. Canonical WNT signaling components in vascular development and barrier formation.

    PubMed

    Zhou, Yulian; Wang, Yanshu; Tischfield, Max; Williams, John; Smallwood, Philip M; Rattner, Amir; Taketo, Makoto M; Nathans, Jeremy

    2014-09-01

    Canonical WNT signaling is required for proper vascularization of the CNS during embryonic development. Here, we used mice with targeted mutations in genes encoding canonical WNT pathway members to evaluate the exact contribution of these components in CNS vascular development and in specification of the blood-brain barrier (BBB) and blood-retina barrier (BRB). We determined that vasculature in various CNS regions is differentially sensitive to perturbations in canonical WNT signaling. The closely related WNT signaling coreceptors LDL receptor-related protein 5 (LRP5) and LRP6 had redundant functions in brain vascular development and barrier maintenance; however, loss of LRP5 alone dramatically altered development of the retinal vasculature. The BBB in the cerebellum and pons/interpeduncular nuclei was highly sensitive to decrements in canonical WNT signaling, and WNT signaling was required to maintain plasticity of barrier properties in mature CNS vasculature. Brain and retinal vascular defects resulting from ablation of Norrin/Frizzled4 signaling were ameliorated by stabilizing β-catenin, while inhibition of β-catenin-dependent transcription recapitulated the vascular development and barrier defects associated with loss of receptor, coreceptor, or ligand, indicating that Norrin/Frizzled4 signaling acts predominantly through β-catenin-dependent transcriptional regulation. Together, these data strongly support a model in which identical or nearly identical canonical WNT signaling mechanisms mediate neural tube and retinal vascularization and maintain the BBB and BRB.

  1. Nitrate foraging by Arabidopsis roots is mediated by the transcription factor TCP20 through the systemic signaling pathway

    PubMed Central

    Guan, Peizhu; Wang, Rongchen; Nacry, Philippe; Breton, Ghislain; Kay, Steve A.; Pruneda-Paz, Jose L.; Davani, Ariea; Crawford, Nigel M.

    2014-01-01

    To compete for nutrients in diverse soil microenvironments, plants proliferate lateral roots preferentially in nutrient-rich zones. For nitrate, root foraging involves local and systemic signaling; however, little is known about the genes that function in the systemic signaling pathway. By using nitrate enhancer DNA to screen a library of Arabidopsis transcription factors in the yeast one-hybrid system, the transcription factor gene TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR1-20 (TCP20) was identified. TCP20, which belongs to an ancient, plant-specific gene family that regulates shoot, flower, and embryo development, was implicated in nitrate signaling by its ability to bind DNA in more than 100 nitrate-regulated genes. Analysis of insertion mutants of TCP20 showed that they had normal primary and lateral root growth on homogenous nitrate media but were impaired in preferential lateral root growth (root foraging) on heterogeneous media in split-root plates. Inhibition of preferential lateral root growth was still evident in the mutants even when ammonium was uniformly present in the media, indicating that the TCP20 response was to nitrate. Comparison of tcp20 mutants with those of nlp7 mutants, which are defective in local control of root growth but not in the root-foraging response, indicated that TCP20 function is independent of and distinct from NLP7 function. Further analysis showed that tcp20 mutants lack systemic control of root growth regardless of the local nitrate concentrations. These results indicate that TCP20 plays a key role in the systemic signaling pathway that directs nitrate foraging by Arabidopsis roots. PMID:25288754

  2. Inhibition of TGF-β Signaling Promotes Human Pancreatic β-Cell Replication

    PubMed Central

    Dhawan, Sangeeta; Dirice, Ercument; Kulkarni, Rohit N.

    2016-01-01

    Diabetes is associated with loss of functional pancreatic β-cells, and restoration of β-cells is a major goal for regenerative therapies. Endogenous regeneration of β-cells via β-cell replication has the potential to restore cellular mass; however, pharmacological agents that promote regeneration or expansion of endogenous β-cells have been elusive. The regenerative capacity of β-cells declines rapidly with age, due to accumulation of p16INK4a, resulting in limited capacity for adult endocrine pancreas regeneration. Here, we show that transforming growth factor-β (TGF-β) signaling via Smad3 integrates with the trithorax complex to activate and maintain Ink4a expression to prevent β-cell replication. Importantly, inhibition of TGF-β signaling can result in repression of the Ink4a/Arf locus, resulting in increased β-cell replication in adult mice. Furthermore, small molecule inhibitors of the TGF-β pathway promote β-cell replication in human islets transplanted into NOD-scid IL-2Rgnull mice. These data reveal a novel role for TGF-β signaling in the regulation of the Ink4a/Arf locus and highlight the potential of using small molecule inhibitors of TGF-β signaling to promote human β-cell replication. PMID:26936960

  3. Mitochondria mediate tumor necrosis factor-alpha/NF-kappaB signaling in skeletal muscle myotubes

    NASA Technical Reports Server (NTRS)

    Li, Y. P.; Atkins, C. M.; Sweatt, J. D.; Reid, M. B.; Hamilton, S. L. (Principal Investigator)

    1999-01-01

    Tumor necrosis factor-alpha (TNF-alpha) is implicated in muscle atrophy and weakness associated with a variety of chronic diseases. Recently, we reported that TNF-alpha directly induces muscle protein degradation in differentiated skeletal muscle myotubes, where it rapidly activates nuclear factor kappaB (NF-kappaB). We also have found that protein loss induced by TNF-alpha is NF-kappaB dependent. In the present study, we analyzed the signaling pathway by which TNF-alpha activates NF-kappaB in myotubes differentiated from C2C12 and rat primary myoblasts. We found that activation of NF-kappaB by TNF-alpha was blocked by rotenone or amytal, inhibitors of complex I of the mitochondrial respiratory chain. On the other hand, antimycin A, an inhibitor of complex III, enhanced TNF-alpha activation of NK-kappaB. These results suggest a key role of mitochondria-derived reactive oxygen species (ROS) in mediating NF-kappaB activation in muscle. In addition, we found that TNF-alpha stimulated protein kinase C (PKC) activity. However, other signal transduction mediators including ceramide, Ca2+, phospholipase A2 (PLA2), and nitric oxide (NO) do not appear to be involved in the activation of NF-kappaB.

  4. Role of Gab1 in Heart, Placenta, and Skin Development and Growth Factor- and Cytokine-Induced Extracellular Signal-Regulated Kinase Mitogen-Activated Protein Kinase Activation

    PubMed Central

    Itoh, Motoyuki; Yoshida, Yuichi; Nishida, Keigo; Narimatsu, Masahiro; Hibi, Masahiko; Hirano, Toshio

    2000-01-01

    Gab1 is a member of the Gab/DOS (Daughter of Sevenless) family of adapter molecules, which contain a pleckstrin homology (PH) domain and potential binding sites for SH2 and SH3 domains. Gab1 is tyrosine phosphorylated upon stimulation of various cytokines, growth factors, and antigen receptors in cell lines and interacts with signaling molecules, such as SHP-2 and phosphatidylinositol 3-kinase, although its biological roles have not yet been established. To reveal the functions of Gab1 in vivo, we generated mice lacking Gab1 by gene targeting. Gab1-deficient embryos died in utero and displayed developmental defects in the heart, placenta, and skin, which were similar to phenotypes observed in mice lacking signals of the hepatocyte growth factor/scatter factor, platelet-derived growth factor, and epidermal growth factor pathways. Consistent with these observations, extracellular signal-regulated kinase mitogen-activated protein (ERK MAP) kinases were activated at much lower levels in cells from Gab1-deficient embryos in response to these growth factors or to stimulation of the cytokine receptor gp130. These results indicate that Gab1 is a common player in a broad range of growth factor and cytokine signaling pathways linking ERK MAP kinase activation. PMID:10779359

  5. Reciprocal signalling by Notch-Collagen V-CALCR retains muscle stem cells in their niche.

    PubMed

    Baghdadi, Meryem B; Castel, David; Machado, Léo; Fukada, So-Ichiro; Birk, David E; Relaix, Frederic; Tajbakhsh, Shahragim; Mourikis, Philippos

    2018-05-01

    The cell microenvironment, which is critical for stem cell maintenance, contains both cellular and non-cellular components, including secreted growth factors and the extracellular matrix 1-3 . Although Notch and other signalling pathways have previously been reported to regulate quiescence of stem cells 4-9 , the composition and source of molecules that maintain the stem cell niche remain largely unknown. Here we show that adult muscle satellite (stem) cells in mice produce extracellular matrix collagens to maintain quiescence in a cell-autonomous manner. Using chromatin immunoprecipitation followed by sequencing, we identified NOTCH1/RBPJ-bound regulatory elements adjacent to specific collagen genes, the expression of which is deregulated in Notch-mutant mice. Moreover, we show that Collagen V (COLV) produced by satellite cells is a critical component of the quiescent niche, as depletion of COLV by conditional deletion of the Col5a1 gene leads to anomalous cell cycle entry and gradual diminution of the stem cell pool. Notably, the interaction of COLV with satellite cells is mediated by the Calcitonin receptor, for which COLV acts as a surrogate local ligand. Systemic administration of a calcitonin derivative is sufficient to rescue the quiescence and self-renewal defects found in COLV-null satellite cells. This study reveals a Notch-COLV-Calcitonin receptor signalling cascade that maintains satellite cells in a quiescent state in a cell-autonomous fashion, and raises the possibility that similar reciprocal mechanisms act in diverse stem cell populations.

  6. Role of fibroblast growth factor receptor signaling in kidney development.

    PubMed

    Bates, Carlton M

    2007-03-01

    Fibroblast growth factor receptors (Fgfrs) are expressed in the ureteric bud and metanephric mesenchyme of the developing kidney. Furthermore, in vitro and in vivo studies have shown that exogenous fibroblast growth factors (Fgfs) increase growth and maturation of the metanephric mesenchyme and ureteric bud. Deletion of fgf7, fgf10, and fgfr2IIIb (the receptor isoform that binds Fgf7 and Fgf10) in mice lead to smaller kidneys with fewer collecting ducts and nephrons. Overexpression of a dominant negative receptor isoform in transgenic mice has revealed more striking defects including renal aplasia or severe dysplasia. Moreover, deletion of many fgf ligands and receptors in mice results in early embryonic lethality, making it difficult to determine their roles in kidney development. Recently, conditional targeting approaches revealed that deletion of fgf8 from the metanephric mesenchyme interrupts nephron formation. Furthermore, deletion of fgfr2 from the ureteric bud resulted in both ureteric bud branching and stromal mesenchymal patterning defects. Deletion of both fgfr1 and fgfr2 in the metanephric mesenchyme resulted in renal aplasia, characterized by defects in metanephric mesenchyme formation and initial ureteric bud elongation and branching. Thus, Fgfr signaling is critical for growth and patterning of all renal lineages at early and later stages of kidney development.

  7. The Mediator Kinase Module Restrains Epidermal Growth Factor Receptor Signaling and Represses Vulval Cell Fate Specification in Caenorhabditis elegans.

    PubMed

    Grants, Jennifer M; Ying, Lisa T L; Yoda, Akinori; You, Charlotte C; Okano, Hideyuki; Sawa, Hitoshi; Taubert, Stefan

    2016-02-01

    Cell signaling pathways that control proliferation and determine cell fates are tightly regulated to prevent developmental anomalies and cancer. Transcription factors and coregulators are important effectors of signaling pathway output, as they regulate downstream gene programs. In Caenorhabditis elegans, several subunits of the Mediator transcriptional coregulator complex promote or inhibit vulva development, but pertinent mechanisms are poorly defined. Here, we show that Mediator's dissociable cyclin dependent kinase 8 (CDK8) module (CKM), consisting of cdk-8, cic-1/Cyclin C, mdt-12/dpy-22, and mdt-13/let-19, is required to inhibit ectopic vulval cell fates downstream of the epidermal growth factor receptor (EGFR)-Ras-extracellular signal-regulated kinase (ERK) pathway. cdk-8 inhibits ectopic vulva formation by acting downstream of mpk-1/ERK, cell autonomously in vulval cells, and in a kinase-dependent manner. We also provide evidence that the CKM acts as a corepressor for the Ets-family transcription factor LIN-1, as cdk-8 promotes transcriptional repression by LIN-1. In addition, we find that CKM mutation alters Mediator subunit requirements in vulva development: the mdt-23/sur-2 subunit, which is required for vulva development in wild-type worms, is dispensable for ectopic vulva formation in CKM mutants, which instead display hallmarks of unrestrained Mediator tail module activity. We propose a model whereby the CKM controls EGFR-Ras-ERK transcriptional output by corepressing LIN-1 and by fine tuning Mediator specificity, thus balancing transcriptional repression vs. activation in a critical developmental signaling pathway. Collectively, these data offer an explanation for CKM repression of EGFR signaling output and ectopic vulva formation and provide the first evidence of Mediator CKM-tail module subunit crosstalk in animals. Copyright © 2016 by the Genetics Society of America.

  8. Nonnegative Tensor Factorization Approach Applied to Fission Chamber’s Output Signals Blind Source Separation

    NASA Astrophysics Data System (ADS)

    Laassiri, M.; Hamzaoui, E.-M.; Cherkaoui El Moursli, R.

    2018-02-01

    Inside nuclear reactors, gamma-rays emitted from nuclei together with the neutrons introduce unwanted backgrounds in neutron spectra. For this reason, powerful extraction methods are needed to extract useful neutron signal from recorded mixture and thus to obtain clearer neutron flux spectrum. Actually, several techniques have been developed to discriminate between neutrons and gamma-rays in a mixed radiation field. Most of these techniques, tackle using analogue discrimination methods. Others propose to use some organic scintillators to achieve the discrimination task. Recently, systems based on digital signal processors are commercially available to replace the analog systems. As alternative to these systems, we aim in this work to verify the feasibility of using a Nonnegative Tensor Factorization (NTF) to blind extract neutron component from mixture signals recorded at the output of fission chamber (WL-7657). This last have been simulated through the Geant4 linked to Garfield++ using a 252Cf neutron source. To achieve our objective of obtaining the best possible neutron-gamma discrimination, we have applied the two different NTF algorithms, which have been found to be the best methods that allow us to analyse this kind of nuclear data.

  9. Wound signaling: The missing link in plant regeneration.

    PubMed

    Chen, Lyuqin; Sun, Beibei; Xu, Lin; Liu, Wu

    2016-10-02

    Wounding is the first event that occurs in plant regeneration. However, wound signaling in plant regeneration is barely understood. Using a simple system of de novo root organogenesis from Arabidopsis thaliana leaf explants, we analyzed the genes downstream of wound signaling. Leaf explants may produce at least two kinds of wound signals to trigger short-term and long-term wound signaling. Short-term wound signaling is primarily involved in controlling auxin behavior and the fate transition of regeneration-competent cells, while long-term wound signaling mainly modulates the cellular environment at the wound site and maintains the auxin level in regeneration-competent cells. YUCCA (YUC) genes, which are involved in auxin biogenesis, are targets of short-term wound signaling in mesophyll cells and of long-term wound signaling in regeneration-competent cells. The expression patterns of YUCs provide important information about the molecular basis of wound signaling in plant regeneration.

  10. Estimating Transmitted-Signal Phase Variations for Uplink Array Antennas

    NASA Technical Reports Server (NTRS)

    Paal, Leslie; Mukai, Ryan; Vilntrotter, Victor; Cornish, Timothy; Lee, Dennis

    2009-01-01

    A method of estimating phase drifts of microwave signals distributed to, and transmitted by, antennas in an array involves the use of the signals themselves as phase references. The method was conceived as part of the solution of the problem of maintaining precise phase calibration required for proper operation of an array of Deep Space Network (DSN) antennas on Earth used for communicating with distant spacecraft at frequencies between 7 and 8 GHz. The method could also be applied to purely terrestrial phased-array radar and other radio antenna array systems. In the DSN application, the electrical lengths (effective signal-propagation path lengths) of the various branches of the system for distributing the transmitted signals to the antennas are not precisely known, and they vary with time. The variations are attributable mostly to thermal expansion and contraction of fiber-optic and electrical signal cables and to a variety of causes associated with aging of signal-handling components. The variations are large enough to introduce large phase drifts at the signal frequency. It is necessary to measure and correct for these phase drifts in order to maintain phase calibration of the antennas. A prior method of measuring phase drifts involves the use of reference-frequency signals separate from the transmitted signals. A major impediment to accurate measurement of phase drifts over time by the prior method is the fact that although DSN reference-frequency sources separate from the transmitting signal sources are stable and accurate enough for most DSN purposes, they are not stable enough for use in maintaining phase calibrations, as required, to within a few degrees over times as long as days or possibly even weeks. By eliminating reliance on the reference-frequency subsystem, the present method overcomes this impediment. In a DSN array to which the present method applies (see figure), the microwave signals to be transmitted are generated by exciters in a signal

  11. Epidermal Growth Factor Signaling towards Proliferation: Modeling and Logic Inference Using Forward and Backward Search

    PubMed Central

    Riesco, Adrián; Santos-Buitrago, Beatriz; De Las Rivas, Javier; Knapp, Merrill; Talcott, Carolyn

    2017-01-01

    In biological systems, pathways define complex interaction networks where multiple molecular elements are involved in a series of controlled reactions producing responses to specific biomolecular signals. These biosystems are dynamic and there is a need for mathematical and computational methods able to analyze the symbolic elements and the interactions between them and produce adequate readouts of such systems. In this work, we use rewriting logic to analyze the cellular signaling of epidermal growth factor (EGF) and its cell surface receptor (EGFR) in order to induce cellular proliferation. Signaling is initiated by binding the ligand protein EGF to the membrane-bound receptor EGFR so as to trigger a reactions path which have several linked elements through the cell from the membrane till the nucleus. We present two different types of search for analyzing the EGF/proliferation system with the help of Pathway Logic tool, which provides a knowledge-based development environment to carry out the modeling of the signaling. The first one is a standard (forward) search. The second one is a novel approach based on narrowing, which allows us to trace backwards the causes of a given final state. The analysis allows the identification of critical elements that have to be activated to provoke proliferation. PMID:28191459

  12. Epidermal Growth Factor Signaling towards Proliferation: Modeling and Logic Inference Using Forward and Backward Search.

    PubMed

    Riesco, Adrián; Santos-Buitrago, Beatriz; De Las Rivas, Javier; Knapp, Merrill; Santos-García, Gustavo; Talcott, Carolyn

    2017-01-01

    In biological systems, pathways define complex interaction networks where multiple molecular elements are involved in a series of controlled reactions producing responses to specific biomolecular signals. These biosystems are dynamic and there is a need for mathematical and computational methods able to analyze the symbolic elements and the interactions between them and produce adequate readouts of such systems. In this work, we use rewriting logic to analyze the cellular signaling of epidermal growth factor (EGF) and its cell surface receptor (EGFR) in order to induce cellular proliferation. Signaling is initiated by binding the ligand protein EGF to the membrane-bound receptor EGFR so as to trigger a reactions path which have several linked elements through the cell from the membrane till the nucleus. We present two different types of search for analyzing the EGF/proliferation system with the help of Pathway Logic tool, which provides a knowledge-based development environment to carry out the modeling of the signaling. The first one is a standard (forward) search. The second one is a novel approach based on narrowing , which allows us to trace backwards the causes of a given final state. The analysis allows the identification of critical elements that have to be activated to provoke proliferation.

  13. Microtubule actin crosslinking factor 1 promotes osteoblast differentiation by promoting β-catenin/TCF1/Runx2 signaling axis.

    PubMed

    Hu, Lifang; Su, Peihong; Yin, Chong; Zhang, Yan; Li, Runzhi; Yan, Kun; Chen, Zhihao; Li, Dijie; Zhang, Ge; Wang, Liping; Miao, Zhiping; Qian, Airong; Xian, Cory J

    2018-02-01

    Osteoblast differentiation is a multistep process delicately regulated by many factors, including cytoskeletal dynamics and signaling pathways. Microtubule actin crosslinking factor 1 (MACF1), a key cytoskeletal linker, has been shown to play key roles in signal transduction and in diverse cellular processes; however, its role in regulating osteoblast differentiation is still needed to be elucidated. To further uncover the functions and mechanisms of action of MACF1 in osteoblast differentiation, we examined effects of MACF1 knockdown (MACF1-KD) in MC3T3-E1 osteoblastic cells on their osteoblast differentiation and associated molecular mechanisms. The results showed that knockdown of MACF1 significantly suppressed mineralization of MC3T3-E1 cells, down-regulated the expression of key osteogenic genes alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2) and type I collagen α1 (Col Iα1). Knockdown of MACF1 dramatically reduced the nuclear translocation of β-catenin, decreased the transcriptional activation of T cell factor 1 (TCF1), and down-regulated the expression of TCF1, lymphoid enhancer-binding factor 1 (LEF1), and Runx2, a target gene of β-catenin/TCF1. In addition, MACF1-KD increased the active level of glycogen synthase kinase-3β (GSK-3β), which is a key regulator for β-catenin signal transduction. Moreover, the reduction of nuclear β-catenin amount and decreased expression of TCF1 and Runx2 were significantly reversed in MACF1-KD cells when treated with lithium chloride, an agonist for β-catenin by inhibiting GSK-3β activity. Taken together, these findings suggest that knockdown of MACF1 in osteoblastic cells inhibits osteoblast differentiation through suppressing the β-catenin/TCF1-Runx2 axis. Thus, a novel role of MACF1 in and a new mechanistic insight of osteoblast differentiation are uncovered. © 2017 Wiley Periodicals, Inc.

  14. Capture of microRNA-bound mRNAs identifies the tumor suppressor miR-34a as a regulator of growth factor signaling.

    PubMed

    Lal, Ashish; Thomas, Marshall P; Altschuler, Gabriel; Navarro, Francisco; O'Day, Elizabeth; Li, Xiao Ling; Concepcion, Carla; Han, Yoon-Chi; Thiery, Jerome; Rajani, Danielle K; Deutsch, Aaron; Hofmann, Oliver; Ventura, Andrea; Hide, Winston; Lieberman, Judy

    2011-11-01

    A simple biochemical method to isolate mRNAs pulled down with a transfected, biotinylated microRNA was used to identify direct target genes of miR-34a, a tumor suppressor gene. The method reidentified most of the known miR-34a regulated genes expressed in K562 and HCT116 cancer cell lines. Transcripts for 982 genes were enriched in the pull-down with miR-34a in both cell lines. Despite this large number, validation experiments suggested that ~90% of the genes identified in both cell lines can be directly regulated by miR-34a. Thus miR-34a is capable of regulating hundreds of genes. The transcripts pulled down with miR-34a were highly enriched for their roles in growth factor signaling and cell cycle progression. These genes form a dense network of interacting gene products that regulate multiple signal transduction pathways that orchestrate the proliferative response to external growth stimuli. Multiple candidate miR-34a-regulated genes participate in RAS-RAF-MAPK signaling. Ectopic miR-34a expression reduced basal ERK and AKT phosphorylation and enhanced sensitivity to serum growth factor withdrawal, while cells genetically deficient in miR-34a were less sensitive. Fourteen new direct targets of miR-34a were experimentally validated, including genes that participate in growth factor signaling (ARAF and PIK3R2) as well as genes that regulate cell cycle progression at various phases of the cell cycle (cyclins D3 and G2, MCM2 and MCM5, PLK1 and SMAD4). Thus miR-34a tempers the proliferative and pro-survival effect of growth factor stimulation by interfering with growth factor signal transduction and downstream pathways required for cell division.

  15. The nucleosome: orchestrating DNA damage signaling and repair within chromatin.

    PubMed

    Agarwal, Poonam; Miller, Kyle M

    2016-10-01

    DNA damage occurs within the chromatin environment, which ultimately participates in regulating DNA damage response (DDR) pathways and repair of the lesion. DNA damage activates a cascade of signaling events that extensively modulates chromatin structure and organization to coordinate DDR factor recruitment to the break and repair, whilst also promoting the maintenance of normal chromatin functions within the damaged region. For example, DDR pathways must avoid conflicts between other DNA-based processes that function within the context of chromatin, including transcription and replication. The molecular mechanisms governing the recognition, target specificity, and recruitment of DDR factors and enzymes to the fundamental repeating unit of chromatin, i.e., the nucleosome, are poorly understood. Here we present our current view of how chromatin recognition by DDR factors is achieved at the level of the nucleosome. Emerging evidence suggests that the nucleosome surface, including the nucleosome acidic patch, promotes the binding and activity of several DNA damage factors on chromatin. Thus, in addition to interactions with damaged DNA and histone modifications, nucleosome recognition by DDR factors plays a key role in orchestrating the requisite chromatin response to maintain both genome and epigenome integrity.

  16. Sp8 and COUP-TF1 reciprocally regulate patterning and Fgf signaling in cortical progenitors.

    PubMed

    Borello, Ugo; Madhavan, Mayur; Vilinsky, Ilya; Faedo, Andrea; Pierani, Alessandra; Rubenstein, John; Campbell, Kenneth

    2014-06-01

    To gain new insights into the transcriptional regulation of cortical development, we examined the role of the transcription factor Sp8, which is downstream of Fgf8 signaling and known to promote rostral cortical development. We have used a binary transgenic system to express Sp8 throughout the mouse telencephalon in a temporally restricted manner. Our results show that misexpression of Sp8 throughout the telencephalon, at early but not late embryonic stages, results in cortical hypoplasia, which is accompanied by increased cell death, reduced proliferation, and precocious neuronal differentiation. Misexpression of Sp8 at early developmental stages represses COUP-TF1 expression, a negative effector of Fgf signaling and a key promoter of posterior cortical identity, while ablation of Sp8 has the opposite effect. In addition, transgenic misexpression of COUP-TF1 resulted in downregulation of Sp8, indicating a reciprocal cross-regulation between these 2 transcription factors. Although Sp8 has been suggested to induce and/or maintain Fgf8 expression in the embryonic telencephalon, neither Fgf8 nor Fgf15 was upregulated using our gain-of-function approach. However, misexpression of Sp8 greatly increased the expression of Fgf target molecules, suggesting enhanced Fgf signaling. Thus, we propose that Sp8 promotes rostral and dorsomedial cortical development by repressing COUP-TF1 and promoting Fgf signaling in pallial progenitors.

  17. Sp8 and COUP-TF1 Reciprocally Regulate Patterning and Fgf Signaling in Cortical Progenitors

    PubMed Central

    Borello, Ugo; Madhavan, Mayur; Vilinsky, Ilya; Faedo, Andrea; Pierani, Alessandra; Rubenstein, John; Campbell, Kenneth

    2014-01-01

    To gain new insights into the transcriptional regulation of cortical development, we examined the role of the transcription factor Sp8, which is downstream of Fgf8 signaling and known to promote rostral cortical development. We have used a binary transgenic system to express Sp8 throughout the mouse telencephalon in a temporally restricted manner. Our results show that misexpression of Sp8 throughout the telencephalon, at early but not late embryonic stages, results in cortical hypoplasia, which is accompanied by increased cell death, reduced proliferation, and precocious neuronal differentiation. Misexpression of Sp8 at early developmental stages represses COUP-TF1 expression, a negative effector of Fgf signaling and a key promoter of posterior cortical identity, while ablation of Sp8 has the opposite effect. In addition, transgenic misexpression of COUP-TF1 resulted in downregulation of Sp8, indicating a reciprocal cross-regulation between these 2 transcription factors. Although Sp8 has been suggested to induce and/or maintain Fgf8 expression in the embryonic telencephalon, neither Fgf8 nor Fgf15 was upregulated using our gain-of-function approach. However, misexpression of Sp8 greatly increased the expression of Fgf target molecules, suggesting enhanced Fgf signaling. Thus, we propose that Sp8 promotes rostral and dorsomedial cortical development by repressing COUP-TF1 and promoting Fgf signaling in pallial progenitors. PMID:23307639

  18. Tgif1 Counterbalances the Activity of Core Pluripotency Factors in Mouse Embryonic Stem Cells.

    PubMed

    Lee, Bum-Kyu; Shen, Wenwen; Lee, Jiwoon; Rhee, Catherine; Chung, Haewon; Kim, Kun-Yong; Park, In-Hyun; Kim, Jonghwan

    2015-10-06

    Core pluripotency factors, such as Oct4, Sox2, and Nanog, play important roles in maintaining embryonic stem cell (ESC) identity by autoregulatory feedforward loops. Nevertheless, the mechanism that provides precise control of the levels of the ESC core factors without indefinite amplification has remained elusive. Here, we report the direct repression of core pluripotency factors by Tgif1, a previously known terminal repressor of TGFβ/activin/nodal signaling. Overexpression of Tgif1 reduces the levels of ESC core factors, whereas its depletion leads to the induction of the pluripotency factors. We confirm the existence of physical associations between Tgif1 and Oct4, Nanog, and HDAC1/2 and further show the level of Tgif1 is not significantly altered by treatment with an activator/inhibitor of the TGFβ/activin/nodal signaling. Collectively, our findings establish Tgif1 as an integral member of the core regulatory circuitry of mouse ESCs that counterbalances the levels of the core pluripotency factors in a TGFβ/activin/nodal-independent manner. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  19. Information flow in a network of dispersed signalers-receivers

    NASA Astrophysics Data System (ADS)

    Halupka, Konrad

    2017-11-01

    I consider a stochastic model of multi-agent communication in regular network. The model describes how dispersed animals exchange information. Each agent can initiate and transfer the signal to its nearest neighbors, who may pass it farther. For an external observer of busy networks, signaling activity may appear random, even though information flow actually thrives. Only when signal initiation and transfer are at low levels do spatiotemporal autocorrelations emerge as clumping signaling activity in space and pink noise time series. Under such conditions, the costs of signaling are moderate, but the signaler can reach a large audience. I propose that real-world networks of dispersed signalers-receivers may self-organize into this state and the flow of information maintains their integrity.

  20. The stem cell factor (SCF)/c-KIT signalling in testis and prostate cancer.

    PubMed

    Cardoso, Henrique J; Figueira, Marília I; Socorro, Sílvia

    2017-12-01

    The stem cell factor (SCF) is a cytokine that specifically binds the tyrosine kinase receptor c-KIT. The SCF/c-KIT interaction leads to receptor dimerization, activation of kinase activity and initiation of several signal transduction pathways that control cell proliferation, apoptosis, differentiation and migration in several tissues. The activity of SCF/c-KIT system is linked with the phosphatidylinositol 3-kinase (PI3-K), the Src, the Janus kinase/signal transducers and activators of transcription (JAK/STAT), the phospholipase-C (PLC-γ) and the mitogen-activated protein kinase (MAPK) pathways. Moreover, it has been reported that cancer cases display an overactivation of c-KIT due to the presence of gain-of-function mutations or receptor overexpression, which renders c-KIT a tempting target for cancer treatment. In the case of male cancers the most documented activated pathways are the PI3-K and Src, both enhancing abnormal cell proliferation. It is also known that the Src activity in prostate cancer cases depends on the presence of tr-KIT, the cytoplasmic truncated variant of c-KIT that is specifically expressed in tumour tissues and, thus, a very interesting target for drug development. The present review provides an overview of the signalling pathways activated by SCF/c-KIT and discusses the potential application of c-KIT inhibitors for treatment of testicular and prostatic cancers.

  1. A mass action model of a Fibroblast Growth Factor signaling pathway and its simplification.

    PubMed

    Gaffney, E A; Heath, J K; Kwiatkowska, M Z

    2008-11-01

    We consider a kinetic law of mass action model for Fibroblast Growth Factor (FGF) signaling, focusing on the induction of the RAS-MAP kinase pathway via GRB2 binding. Our biologically simple model suffers a combinatorial explosion in the number of differential equations required to simulate the system. In addition to numerically solving the full model, we show that it can be accurately simplified. This requires combining matched asymptotics, the quasi-steady state hypothesis, and the fact subsets of the equations decouple asymptotically. Both the full and simplified models reproduce the qualitative dynamics observed experimentally and in previous stochastic models. The simplified model also elucidates both the qualitative features of GRB2 binding and the complex relationship between SHP2 levels, the rate SHP2 induces dephosphorylation and levels of bound GRB2. In addition to providing insight into the important and redundant features of FGF signaling, such work further highlights the usefulness of numerous simplification techniques in the study of mass action models of signal transduction, as also illustrated recently by Borisov and co-workers (Borisov et al. in Biophys. J. 89, 951-966, 2005, Biosystems 83, 152-166, 2006; Kiyatkin et al. in J. Biol. Chem. 281, 19925-19938, 2006). These developments will facilitate the construction of tractable models of FGF signaling, incorporating further biological realism, such as spatial effects or realistic binding stoichiometries, despite a more severe combinatorial explosion associated with the latter.

  2. Multipronged attenuation of macrophage-colony stimulating factor signaling by Epstein-Barr virus BARF1

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shim, Ann Hye-Ryong; Chang, Rhoda Ahn; Chen, Xiaoyan

    The ubiquitous EBV causes infectious mononucleosis and is associated with several types of cancers. The EBV genome encodes an early gene product, BARF1, which contributes to pathogenesis, potentially through growth-altering and immune-modulating activities, but the mechanisms for such activities are poorly understood. We have determined the crystal structure of BARF1 in complex with human macrophage-colony stimulating factor (M-CSF), a hematopoietic cytokine with pleiotropic functions in development and immune response. BARF1 and M-CSF form a high-affinity, stable, ring-like complex in both solution and the crystal, with a BARF1 hexameric ring surrounded by three M-CSF dimers in triangular array. The binding ofmore » BARF1 to M-CSF dramatically reduces but does not completely abolish M-CSF binding and signaling through its cognate receptor FMS. A three-pronged down-regulation mechanism is proposed to explain the biological effect of BARF1 on M-CSF:FMS signaling. These prongs entail control of the circulating and effective local M-CSF concentration, perturbation of the receptor-binding surface of M-CSF, and imposition of an unfavorable global orientation of the M-CSF dimer. Each prong may reduce M-CSF:FMS signaling to a limited extent but in combination may alter M-CSF:FMS signaling dramatically. The downregulating mechanism of BARF1 underlines a viral modulation strategy, and provides a basis for understanding EBV pathogenesis.« less

  3. Mitogenic signaling pathways of growth factors can be distinguished by the involvement of pertussis toxin-sensitive guanosine triphosphate-binding protein and of protein kinase C.

    PubMed Central

    Nishizawa, N; Okano, Y; Chatani, Y; Amano, F; Tanaka, E; Nomoto, H; Nozawa, Y; Kohno, M

    1990-01-01

    We have examined the possible involvements of pertussis toxin (PT)-sensitive guanosine triphosphate (GTP)-binding protein (Gp) and protein kinase C (PKC) in the mitogenic signaling pathways of various growth factors by the use of PT-pretreated and/or 12-O-tetradecanoyl phorbol-13-acetate (TPA)-pretreated mouse fibroblasts. Effects of PT pretreatment (inactivation of PT-sensitive Gp) and TPA pretreatment (depletion of PKC) on mitogen-induced DNA synthesis varied significantly and systematically in response to growth factors: mitogenic responses of cells to thrombin, bombesin, and bradykinin were almost completely abolished both in PT- and TPA-pretreated cells; responses to epidermal growth factor (EGF), platelet-derived growth factor (PDGF), and vanadate were reduced to approximately 50% both in PT- and TPA-pretreated cells compared with native cells; response to basic fibroblast growth factor (bFGF) was not affected in PT-pretreated cells but was inhibited to some extent in TPA-pretreated cells. Thus, growth factors examined have been classified into three groups with regard to the involvements of PT-sensitive Gp and PKC in their signal transduction pathways. Binding of each growth factor to its receptor was not affected significantly by pretreatment of cells with PT or TPA. Inhibitory effects of PT and TPA pretreatment on each mitogen-induced DNA synthesis were not additive, suggesting that the functions of PT-sensitive Gp and PKC lie on an identical signal transduction pathway. Although all three groups of mitogens activated PKC, signaling of each growth factor depends to a varying extent on the function of PKC. Our results indicate that a single peptide growth factor such as EGF, PDGF, or bFGF acts through multiple signaling pathways to induce cell proliferation. Images PMID:2129194

  4. Bridging the Gap between Aetiological and Maintaining Factors in Social Anxiety Disorder: The Impact of Socially Traumatic Experiences on Beliefs, Imagery and Symptomatology.

    PubMed

    Norton, Alice R; Abbott, Maree J

    2017-05-01

    A number of key environmental factors during childhood have been implicated in the aetiology of social anxiety disorder (SAD), including aversive social experiences, traumatic life events and parent-child interaction. However, understanding the nature, interactions and relative contributions of these factors remains unclear. Furthermore, the relation of aversive social experiences to the development of key maintaining factors in SAD requires elucidation. The current study aimed to extend previous research regarding the aetiology of SAD by investigating the relationship between key environmental factors in childhood, negative beliefs and self-imagery, and the development of SAD. Social anxiety disorder individuals (n = 40, 87.5% female, M age  = 20.25 years) completed self-report measures of social anxiety symptomatology, traumatic experiences and parenting style. In addition, participants were administered interviews assessing various domains of childhood trauma, as well as negative self-imagery and associated socially traumatic memories. Participants reported a high frequency of early traumatic experiences across all domains (physical, emotional, sexual, social and non-relational), as well as a high degree of parental overcontrol. However, social anxiety symptomatology was most strongly correlated with socially traumatic experiences, and mediation analyses suggest that appraisal of aversive social/peer experiences accounts for the relationship of SAD symptomatology with negative self-beliefs and imagery. These outcomes suggest that social trauma may be a key proximal cause of SAD development, leading to the development of negative beliefs and imagery that subsequently maintain the disorder. These findings have implications for understanding SAD aetiology, and improving treatment outcomes for the disorder. Copyright © 2016 John Wiley & Sons, Ltd. Negative social experiences have been implicated in the development of social anxiety disorder (SAD), but the

  5. Traffic signal operations and maintenance staffing guidelines.

    DOT National Transportation Integrated Search

    2009-03-01

    This report provides a guideline to estimate the staffing and resource needs required to effectively : operate and maintain traffic signal systems. The results of a survey performed under this project, as : well as a review of the literature and othe...

  6. Traffic signal operations and maintenance staffing guidelines

    DOT National Transportation Integrated Search

    2009-03-01

    This report provides a guideline to estimate the staffing and resource needs required to effectively operate and maintain traffic signal systems. The results of a survey performed under this project, as well as a review of the literature and other su...

  7. In situ analysis of integrin and growth factor receptor signaling pathways in human glioblastomas suggests overlapping relationships with focal adhesion kinase activation.

    PubMed

    Riemenschneider, Markus J; Mueller, Wolf; Betensky, Rebecca A; Mohapatra, Gayatry; Louis, David N

    2005-11-01

    Deregulated integrin signaling is common in cancers, including glioblastoma. Integrin binding and growth factor receptor signaling activate focal adhesion kinase (FAK) and subsequently up-regulate extracellular regulated kinases (ERK-1/2), leading to cell-cycle progression and cell migration. Most studies of this pathway have used in vitro systems or tumor lysate-based approaches. We examined these pathways primarily in situ using a panel of 30 glioblastomas and gene expression arrays, immunohistochemistry, and fluorescence in situ hybridization, emphasizing the histological distribution of molecular changes. Within individual tumors, increased expression of FAK, p-FAK, paxillin, ERK-1/2, and p-ERK-1/2 occurred in regions of elevated EGFR and/or PDGFRA expression. Moreover, FAK activation levels correlated with EGFR and PDGFRA expression, and p-FAK and EGFR expression co-localized at the single-cell level. In addition, integrin expression was enriched in EGFR/PDGFRA-overexpressing areas but was more regionally confined than FAK, p-FAK, and paxillin. Integrins beta8 and alpha5beta1 were most commonly expressed, often in a perinecrotic or perivascular pattern. Taken together, our data suggest that growth factor receptor overexpression facilitates alterations in the integrin signaling pathway. Thus, FAK may act in glioblastoma as a downstream target of growth factor signaling, with integrins enhancing the impact of such signaling in the tumor microenvironment.

  8. Pin1 down-regulates transforming growth factor-beta (TGF-beta) signaling by inducing degradation of Smad proteins.

    PubMed

    Nakano, Ayako; Koinuma, Daizo; Miyazawa, Keiji; Uchida, Takafumi; Saitoh, Masao; Kawabata, Masahiro; Hanai, Jun-ichi; Akiyama, Hirotada; Abe, Masahiro; Miyazono, Kohei; Matsumoto, Toshio; Imamura, Takeshi

    2009-03-06

    Transforming growth factor-beta (TGF-beta) is crucial in numerous cellular processes, such as proliferation, differentiation, migration, and apoptosis. TGF-beta signaling is transduced by intracellular Smad proteins that are regulated by the ubiquitin-proteasome system. Smad ubiquitin regulatory factor 2 (Smurf2) prevents TGF-beta and bone morphogenetic protein signaling by interacting with Smads and inducing their ubiquitin-mediated degradation. Here we identified Pin1, a peptidylprolyl cis-trans isomerase, as a novel protein binding Smads. Pin1 interacted with Smad2 and Smad3 but not Smad4; this interaction was enhanced by the phosphorylation of (S/T)P motifs in the Smad linker region. (S/T)P motif phosphorylation also enhanced the interaction of Smad2/3 with Smurf2. Pin1 reduced Smad2/3 protein levels in a manner dependent on its peptidyl-prolyl cis-trans isomerase activity. Knockdown of Pin1 increased the protein levels of endogenous Smad2/3. In addition, Pin1 both enhanced the interaction of Smurf2 with Smads and enhanced Smad ubiquitination. Pin1 inhibited TGF-beta-induced transcription and gene expression, suggesting that Pin1 negatively regulates TGF-beta signaling by down-regulating Smad2/3 protein levels via induction of Smurf2-mediated ubiquitin-proteasomal degradation.

  9. N-methyl-N'-nitro-N-nitrosoguanidine interferes with the epidermal growth factor receptor-mediated signaling pathway.

    PubMed

    Gao, Zhihua; Yang, Jun; Huang, Yun; Yu, Yingnian

    2005-03-01

    Many environmental factors, such as ultraviolet (UV) and arsenic, can induce the clustering of cell surface receptors, including epidermal growth factor receptor (EGFR). This is accompanied by the phosphorylation of the receptors and the activation of ensuing cellular signal transduction pathways, which are implicated in the various cellular responses caused by the exposure to these factors. In this study, we have shown that N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), an alkylating agent, also induced the clustering of EGFR in human amnion FL cells, which was similar in morphology to that of epidermal growth factor treatment. However, MNNG treatment did not activate Ras, the downstream mediator in EGFR signaling pathway, as compared to EGF treatment. The autophosphorylation of tyrosine residues Y1068 and Y1173 at the intracellular domain of EGFR, which is related to Ras activation under EGF treatment, was also not observed by MNNG exposure. Interestingly, although MNNG did not affect the binding of EGF to EGFR, MNNG can interfere with EGF function. For instance, pre-incubating FL cells with MNNG inhibited the autophosphorylation of EGFR by EGF treatment, as well as the activation of Ras. In addition, the phosphorylation of Y845 on EGFR by EGF, which is mediated through c-Src or related kinases but not autophosphorylation, was also affected by MNNG. Therefore, MNNG may influence the tyrosine kinase activity as well as the phosphorylation of EGFR through its interaction with EGFR.

  10. Ligand-activated BMP signaling inhibits cell differentiation and death to promote melanoma

    PubMed Central

    Venkatesan, Arvind M.; Vyas, Rajesh; Gramann, Alec K.; Gujja, Sharvari; Bhatnagar, Sanchita; Gomes, Camilla Borges Ferreira; Xi, Hualin Simon; Lian, Christine G.; Houvras, Yariv; Edwards, Yvonne J. K.; Deng, April; Ceol, Craig J.

    2017-01-01

    Oncogenomic studies indicate that copy number variation (CNV) alters genes involved in tumor progression; however, identification of specific driver genes affected by CNV has been difficult, as these rearrangements are often contained in large chromosomal intervals among several bystander genes. Here, we addressed this problem and identified a CNV-targeted oncogene by performing comparative oncogenomics of human and zebrafish melanomas. We determined that the gene encoding growth differentiation factor 6 (GDF6), which is the ligand for the BMP family, is recurrently amplified and transcriptionally upregulated in melanoma. GDF6-induced BMP signaling maintained a trunk neural crest gene signature in melanomas. Additionally, GDF6 repressed the melanocyte differentiation gene MITF and the proapoptotic factor SOX9, thereby preventing differentiation, inhibiting cell death, and promoting tumor growth. GDF6 was specifically expressed in melanomas but not melanocytes. Moreover, GDF6 expression levels in melanomas were inversely correlated with patient survival. Our study has identified a fundamental role for GDF6 and BMP signaling in governing an embryonic cell gene signature to promote melanoma progression, thus providing potential opportunities for targeted therapy to treat GDF6-positive cancers. PMID:29202482

  11. Widespread hyperalgesia in irritable bowel syndrome is dynamically maintained by tonic visceral impulse input and placebo/nocebo factors: Evidence from human psychophysics, animal models, and neuroimaging

    PubMed Central

    Price, Donald D.; Craggs, Jason G.; Zhou, QiQi; Verne, G. Nicholas; Perlstein, William M.; Robinson, Michael E.

    2010-01-01

    Irritable bowel syndrome (IBS) is a highly prevalent gastrointestinal disorder that is often accompanied by both visceral and somatic hyperalgesia (enhanced pain from colorectal and somatic stimuli). Neural mechanisms of both types of hyperalgesia have been analyzed by neuroimaging studies of IBS patients and animal analog studies of “IBS-like” rats with delayed rectal and somatic hypersensitivity. Results from these studies suggest that pains associated with both visceral and widespread secondary cutaneous hyperalgesia are dynamically maintained by tonic impulse input from the non-inflamed colon and/or rectum and by brain-to-spinal cord facilitation. Enhanced visceral and somatic pains are accompanied by enhanced pain-related brain activity in IBS patients as compared to normal control subjects; placebos can normalize both their hyperalgesia and enhanced brain activity. That pain in IBS which is likely to be at least partly maintained by peripheral impulse input from the colon/rectum is supported by results showing that local rectal–colonic anesthesia normalizes visceral and somatic hyperalgesia in IBS patients and visceral and somatic hypersensitivity in “IBS-like” rats. Yet these forms of hyperalgesia are also highly modifiable by placebo and nocebo factors (e.g., expectations of relief or distress, respectively). Our working hypothesis is that synergistic interactions occur between placebo/nocebo factors and enhanced afferent processing so as to enhance, maintain, or reduce hyperalgesia in IBS. This explanatory model may be relevant to other persistent pain conditions. PMID:19375508

  12. LRP1 protects the vasculature by regulating levels of connective tissue growth factor and HtrA1.

    PubMed

    Muratoglu, Selen C; Belgrave, Shani; Hampton, Brian; Migliorini, Mary; Coksaygan, Turhan; Chen, Ling; Mikhailenko, Irina; Strickland, Dudley K

    2013-09-01

    Low-density lipoprotein receptor-related protein 1 (LRP1) is a large endocytic and signaling receptor that is abundant in vascular smooth muscle cells. Mice in which the lrp1 gene is deleted in smooth muscle cells (smLRP1(-/-)) on a low-density lipoprotein receptor-deficient background display excessive platelet derived growth factor-signaling, smooth muscle cell proliferation, aneurysm formation, and increased susceptibility to atherosclerosis. The objectives of the current study were to examine the potential of LRP1 to modulate vascular physiology under nonatherogenic conditions. We found smLRP1(-/-) mice to have extensive in vivo aortic dilatation accompanied by disorganized and degraded elastic lamina along with medial thickening of the arterial vessels resulting from excess matrix deposition. Surprisingly, this was not attributable to excessive platelet derived growth factor-signaling. Rather, quantitative differential proteomic analysis revealed that smLRP1(-/-) vessels contain a 4-fold increase in protein levels of high-temperature requirement factor A1 (HtrA1), which is a secreted serine protease that is known to degrade matrix components and to impair elastogenesis, resulting in fragmentation of elastic fibers. Importantly, our study discovered that HtrA1 is a novel LRP1 ligand. Proteomics analysis also identified excessive accumulation of connective tissue growth factor, an LRP1 ligand and a key mediator of fibrosis. Our findings suggest a critical role for LRP1 in maintaining the integrity of vessels by regulating protease activity as well as matrix deposition by modulating HtrA1 and connective tissue growth factor protein levels. This study highlights 2 new molecules, connective tissue growth factor and HtrA1, which contribute to detrimental changes in the vasculature and, therefore, represent new target molecules for potential therapeutic intervention to maintain vessel wall homeostasis.

  13. RBPJ maintains brain tumor–initiating cells through CDK9-mediated transcriptional elongation

    PubMed Central

    Xie, Qi; Wu, Qiulian; Kim, Leo; Miller, Tyler E.; Liau, Brian B.; Mack, Stephen C.; Yang, Kailin; Factor, Daniel C.; Fang, Xiaoguang; Huang, Zhi; Zhou, Wenchao; Alazem, Kareem; Wang, Xiuxing; Bernstein, Bradley E.; Bao, Shideng; Rich, Jeremy N.

    2016-01-01

    Glioblastomas co-opt stem cell regulatory pathways to maintain brain tumor–initiating cells (BTICs), also known as cancer stem cells. NOTCH signaling has been a molecular target in BTICs, but NOTCH antagonists have demonstrated limited efficacy in clinical trials. Recombining binding protein suppressor of hairless (RBPJ) is considered a central transcriptional mediator of NOTCH activity. Here, we report that pharmacologic NOTCH inhibitors were less effective than targeting RBPJ in suppressing tumor growth. While NOTCH inhibitors decreased canonical NOTCH gene expression, RBPJ regulated a distinct profile of genes critical to BTIC stemness and cell cycle progression. RBPJ was preferentially expressed by BTICs and required for BTIC self-renewal and tumor growth. MYC, a key BTIC regulator, bound the RBPJ promoter and treatment with a bromodomain and extraterminal domain (BET) family bromodomain inhibitor decreased MYC and RBPJ expression. Proteomic studies demonstrated that RBPJ binds CDK9, a component of positive transcription elongation factor b (P-TEFb), to target gene promoters, enhancing transcriptional elongation. Collectively, RBPJ links MYC and transcriptional control through CDK9, providing potential nodes of fragility for therapeutic intervention, potentially distinct from NOTCH. PMID:27322055

  14. Coated Pit-mediated Endocytosis of the Type I Transforming Growth Factor-β (TGF-β) Receptor Depends on a Di-leucine Family Signal and Is Not Required for Signaling*

    PubMed Central

    Shapira, Keren E.; Gross, Avner; Ehrlich, Marcelo; Henis, Yoav I.

    2012-01-01

    The roles of transforming growth factor-β (TGF-β) receptor endocytosis in signaling have been investigated in numerous studies, mainly through the use of endocytosis inhibitory treatments, yielding conflicting results. Two potential sources for these discrepancies were the pleiotropic effects of a general blockade of specific internalization pathways and the scarce information on the regulation of the endocytosis of the signal-transducing type I TGF-β receptor (TβRI). Here, we employed extracellularly tagged myc-TβRI (wild type, truncation mutants, and a series of endocytosis-defective and endocytosis-enhanced mutants) to directly investigate the relationship between TβRI endocytosis and signaling. Our findings indicate that TβRI is targeted for constitutive clathrin-mediated endocytosis via a di-leucine (Leu180-Ile181) signal and an acidic cluster motif. Using Smad-dependent transcriptional activation assays and following Smad2/3 nuclear translocation in response to TGF-β stimulation, we show that TβRI endocytosis is dispensable for TGF-β signaling and may play a role in signal termination. Alanine replacement of Leu180-Ile181 led to partial constitutive activation of TβRI, resulting in part from its retention at the plasma membrane and in part from potential alterations of TβRI regulatory interactions in the vicinity of the mutated residues. PMID:22707720

  15. Progesterone-Mediated Non-Classical Signaling.

    PubMed

    Garg, Deepika; Ng, Sinnie Sin Man; Baig, K Maravet; Driggers, Paul; Segars, James

    2017-09-01

    Progesterone is essential for pregnancy maintenance and menstrual cycle regulation. Hormone action has been primarily ascribed to the well-characterized classical signaling pathway involving ligand binding, activation of nuclear progesterone receptors (PRs), and subsequent activation of genes containing progesterone response elements (PREs). Recent studies have revealed progesterone actions via non-classical signaling pathways, often mediated by non-genomic signaling. Progesterone signaling, in conjunction with growth factor signaling, impacts on the function of growth factors and regulates important physiological actions such as cell growth and remodeling, as well as apoptosis. This review focuses on non-classical progesterone signaling pathways, both including and excluding PR, and highlights how research in this area will provide a better understanding of progesterone actions and may inform novel therapeutic strategies. Copyright © 2017. Published by Elsevier Ltd.

  16. Frequency domain laser velocimeter signal processor

    NASA Technical Reports Server (NTRS)

    Meyers, James F.; Murphy, R. Jay

    1991-01-01

    A new scheme for processing signals from laser velocimeter systems is described. The technique utilizes the capabilities of advanced digital electronics to yield a signal processor capable of operating in the frequency domain maximizing the information obtainable from each signal burst. This allows a sophisticated approach to signal detection and processing, with a more accurate measurement of the chirp frequency resulting in an eight-fold increase in measurable signals over the present high-speed burst counter technology. Further, the required signal-to-noise ratio is reduced by a factor of 32, allowing measurements within boundary layers of wind tunnel models. Measurement accuracy is also increased up to a factor of five.

  17. Activation of YUCCA5 by the Transcription Factor TCP4 Integrates Developmental and Environmental Signals to Promote Hypocotyl Elongation in Arabidopsis.

    PubMed

    Challa, Krishna Reddy; Aggarwal, Pooja; Nath, Utpal

    2016-09-05

    Cell expansion is an essential process in plant morphogenesis and is regulated by the coordinated action of environmental stimuli and endogenous factors, such as the phytohormones auxin and brassinosteroid. Although the biosynthetic pathways that generate these hormones and their downstream signaling mechanisms have been extensively studied, the upstream transcriptional network that modulates their levels and connects their action to cell morphogenesis is less clear. Here we show that the miR319-regulated TCP (TEOSINTE BRANCHED 1, CYCLODEA, PROLIFERATING CELL FACTORS) transcription factors, notably TCP4, directly activate YUCCA5 transcription and integrate the auxin response to a brassinosteroid-dependent molecular circuit that promotes cell elongation in Arabidopsis hypocotyls. Further, TCP4 modulates the common transcriptional network downstream to auxin-BR signaling, which is also triggered by environmental cues, such as light, to promote cell expansion. Our study links TCP function with the hormone response during cell morphogenesis and shows that developmental and environmental signals converge on a common transcriptional network to promote cell elongation. {copyright, serif} 2016 American Society of Plant Biologists. All rights reserved.

  18. Nuclear factor of activated T-cells 5 increases intestinal goblet cell differentiation through an mTOR/Notch signaling pathway

    PubMed Central

    Zhou, Yuning; Wang, Qingding; Weiss, Heidi L.; Evers, B. Mark

    2014-01-01

    The intestinal mucosa undergoes a continual process of proliferation, differentiation, and apoptosis that is regulated by multiple signaling pathways. Previously, we have shown that the nuclear factor of activated T-cells 5 (NFAT5) is involved in the regulation of intestinal enterocyte differentiation. Here we show that treatment with sodium chloride (NaCl), which activates NFAT5 signaling, increased mTORC1 repressor regulated in development and DNA damage response 1 (REDD1) protein expression and inhibited mTOR signaling; these alterations were attenuated by knockdown of NFAT5. Knockdown of NFAT5 activated mammalian target of rapamycin (mTOR) signaling and significantly inhibited REDD1 mRNA expression and protein expression. Consistently, overexpression of NFAT5 increased REDD1 expression. In addition, knockdown of REDD1 activated mTOR and Notch signaling, whereas treatment with mTOR inhibitor rapamycin repressed Notch signaling and increased the expression of the goblet cell differentiation marker mucin 2 (MUC2). Moreover, knockdown of NFAT5 activated Notch signaling and decreased MUC2 expression, while overexpression of NFAT5 inhibited Notch signaling and increased MUC2 expression. Our results demonstrate a role for NFAT5 in the regulation of mTOR signaling in intestinal cells. Importantly, these data suggest that NFAT5 participates in the regulation of intestinal homeostasis via the suppression of mTORC1/Notch signaling pathway. PMID:25057011

  19. Blockade of epidermal growth factor receptor signaling leads to inhibition of renal cell carcinoma growth in the bone of nude mice.

    PubMed

    Weber, Kristy L; Doucet, Michele; Price, Janet E; Baker, Cheryl; Kim, Sun Jin; Fidler, Isaiah J

    2003-06-01

    Renal cell carcinoma (RCC) frequently produces metastases to the musculoskeletal system that are a major source of morbidity in the form of pain, immobilization, fractures, neurological compromise, and a decreased ability to perform activities of daily living. Patients with metastatic RCC therefore have a dismal prognosis because there is no effective adjuvant treatment for this disease. Because the epidermal growth factor receptor (EGF-R) signaling cascade is important in the growth and metastasis of RCC, its blockade has been hypothesized to inhibit tumor growth and hence prevent resultant bone destruction. We determined whether blockade of EGF-R by the tyrosine kinase inhibitor PKI 166 inhibited the growth of RCC in bone. We use a novel cell line, RBM1-IT4, established from a human RCC bone metastasis. Protein and mRNA expression of the ligands and receptors was assessed by Western and Northern blots. The stimulation of RBM1-IT4 cells with epidermal growth factor or transforming growth factor alpha resulted in increased cellular proliferation and tyrosine kinase autophosphorylation. PKI 166 prevented these effects. First, RBM1-IT4 cells were implanted into the tibia of nude mice, where they established lytic, progressively growing lesions, after which the mice were treated with PKI 166 alone or in combination with paclitaxel (Taxol). Immunohistochemical analysis revealed that tumor cells and tumor-associated endothelial cells in control mice expressed activated EGF-R. Treatment of mice with PKI 166 alone or in combination with Taxol produced a significant decrease in the incidence and size of bone lesions as compared with the results in control or Taxol-treated mice (P < 0.001). Treatment with PKI 166 also decreased the expression of phosphorylated EGF-R by tumor cells and tumor-associated endothelial cells, and this was even more pronounced with PKI 166 plus Taxol treatment. The PKI 166 plus Taxol combination produced apoptosis of tumor cells and tumor

  20. Feedback Activation of Basic Fibroblast Growth Factor Signaling via the Wnt/β-Catenin Pathway in Skin Fibroblasts

    PubMed Central

    Wang, Xu; Zhu, Yuting; Sun, Congcong; Wang, Tao; Shen, Yingjie; Cai, Wanhui; Sun, Jia; Chi, Lisha; Wang, Haijun; Song, Na; Niu, Chao; Shen, Jiayi; Cong, Weitao; Zhu, Zhongxin; Xuan, Yuanhu; Li, Xiaokun; Jin, Litai

    2017-01-01

    Skin wound healing is a complex process requiring the coordinated behavior of many cell types, especially in the proliferation and migration of fibroblasts. Basic fibroblast growth factor (bFGF) is a member of the FGF family that promotes fibroblast migration, but the underlying molecular mechanism remains elusive. The present RNA sequencing study showed that the expression levels of several canonical Wnt pathway genes, including Wnt2b, Wnt3, Wnt11, T-cell factor 7 (TCF7), and Frizzled 8 (FZD8) were modified by bFGF stimulation in fibroblasts. Enzyme-linked immunosorbent assay (ELISA) analysis also showed that Wnt pathway was activated under bFGF treatment. Furthermore, treatment of fibroblasts with lithium chloride or IWR-1, an inducer and inhibitor of the Wnt signaling pathway, respectively, promoted and inhibited cell migration. Also, levels of cytosolic glycogen synthase kinase 3 beta phosphorylated at serine9 (pGSK3β Ser9) and nuclear β-catenin were increased upon exposure to bFGF. Molecular and biochemical assays indicated that phosphoinositide 3-kinase (PI3K) signaling activated the GSK3β/β-catenin/Wnt signaling pathway via activation of c-Jun N-terminal kinase (JNK), suggesting that PI3K and JNK act at the upstream of β-catenin. In contrast, knock-down of β-catenin delayed fibroblast cell migration even under bFGF stimulation. RNA sequencing analysis of β-catenin knock-down fibroblasts demonstrated that β-catenin positively regulated the transcription of bFGF and FGF21. Moreover, FGF21 treatment activated AKT and JNK, and accelerated fibroblast migration to a similar extent as bFGF does. In addition, ELISA analysis demonstrated that both of bFGF and FGF21 were auto secretion factor and be regulated by Wnt pathway stimulators. Taken together, our analyses define a feedback regulatory loop between bFGF (FGF21) and Wnt signaling acting through β-catenin in skin fibroblasts. PMID:28217097

  1. To signal or not to signal: that should not be the question.

    PubMed

    Faw, Harold W

    2013-10-01

    The purpose of the present research was to examine rates of turn signal use, a positive and potentially valuable means by which drivers can communicate. A second purpose was to explore factors that might impact these rates, including the modeling influence of other drivers. A series of observations involving more than 5600 vehicles making turns were recorded at a variety of intersections in British Columbia, Canada. Though the occurrence of signal use varied widely, ranging from a low of 54% to a high of 95%, the overall rate was 76%. Drivers used turn signals significantly less often when making right as compared with left turns, when traffic volume was higher, and when a designated turning lane was provided. In addition, compared with drivers following another vehicle not using signals, those following a vehicle with turn signals on were significantly more likely to activate their turn signals, suggesting a possible modeling effect. Both internal and external influences on turn signal use by drivers were considered. External factors explored in this research included direction of turn, traffic volume, intersection configuration, and the example of other drivers. It was concluded that the practice of signaling turns merits more research attention, since consistent use of signals is a potential contributor to enhanced safety for all road users. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Recent research on the growth plate: Advances in fibroblast growth factor signaling in growth plate development and disorders.

    PubMed

    Xie, Yangli; Zhou, Siru; Chen, Hangang; Du, Xiaolan; Chen, Lin

    2014-08-01

    Skeletons are formed through two distinct developmental actions, intramembranous ossification and endochondral ossification. During embryonic development, most bone is formed by endochondral ossification. The growth plate is the developmental center for endochondral ossification. Multiple signaling pathways participate in the regulation of endochondral ossification. Fibroblast growth factor (FGF)/FGF receptor (FGFR) signaling has been found to play a vital role in the development and maintenance of growth plates. Missense mutations in FGFs and FGFRs can cause multiple genetic skeletal diseases with disordered endochondral ossification. Clarifying the molecular mechanisms of FGFs/FGFRs signaling in skeletal development and genetic skeletal diseases will have implications for the development of therapies for FGF-signaling-related skeletal dysplasias and growth plate injuries. In this review, we summarize the recent advances in elucidating the role of FGFs/FGFRs signaling in growth plate development, genetic skeletal disorders, and the promising therapies for those genetic skeletal diseases resulting from FGFs/FGFRs dysfunction. Finally, we also examine the potential important research in this field in the future. © 2014 Society for Endocrinology.

  3. Transforming Growth Factor ß Recruits Persistent MAPK Signaling to Regulate Long-Term Memory Consolidation in "Aplysia Californica"

    ERIC Educational Resources Information Center

    Shobe, Justin; Philips, Gary T.; Carew, Thomas J.

    2016-01-01

    In this study, we explore the mechanistic relationship between growth factor signaling and kinase activity that supports the protein synthesis-dependent phase of long-term memory (LTM) consolidation for sensitization of "Aplysia." Specifically, we examine LTM for tail shock-induced sensitization of the tail-elicited siphon withdrawal…

  4. Optimal experimental design in an epidermal growth factor receptor signalling and down-regulation model.

    PubMed

    Casey, F P; Baird, D; Feng, Q; Gutenkunst, R N; Waterfall, J J; Myers, C R; Brown, K S; Cerione, R A; Sethna, J P

    2007-05-01

    We apply the methods of optimal experimental design to a differential equation model for epidermal growth factor receptor signalling, trafficking and down-regulation. The model incorporates the role of a recently discovered protein complex made up of the E3 ubiquitin ligase, Cbl, the guanine exchange factor (GEF), Cool-1 (beta -Pix) and the Rho family G protein Cdc42. The complex has been suggested to be important in disrupting receptor down-regulation. We demonstrate that the model interactions can accurately reproduce the experimental observations, that they can be used to make predictions with accompanying uncertainties, and that we can apply ideas of optimal experimental design to suggest new experiments that reduce the uncertainty on unmeasurable components of the system.

  5. Key role of integrin α(IIb)β (3) signaling to Syk kinase in tissue factor-induced thrombin generation.

    PubMed

    van der Meijden, Paola E J; Feijge, Marion A H; Swieringa, Frauke; Gilio, Karen; Nergiz-Unal, Reyhan; Hamulyák, Karly; Heemskerk, Johan W M

    2012-10-01

    The fibrin(ogen) receptor, integrin α(IIb)β(3), has a well-established role in platelet spreading, aggregation and clot retraction. How α(IIb)β(3) contributes to platelet-dependent coagulation is less well resolved. Here, we demonstrate that the potent suppressing effect of clinically used α(IIb)β(3) blockers on tissue factor-induced thrombin generation is linked to diminished platelet Ca(2+) responses and phosphatidylserine (PS) exposure. The same blockers suppress these responses in platelets stimulated with collagen and thrombin receptor agonists, whereas added fibrinogen potentiates these responses. In platelets spreading on fibrinogen, outside-in α(IIb)β(3) signaling similarly enhances thrombin-induced Ca(2+) rises and PS exposure. These responses are reduced in α(IIb)β(3)-deficient platelets from patients with Glanzmann's thrombasthenia. Furthermore, the contribution of α(IIb)β(3) to tissue factor-induced platelet Ca(2+) rises, PS exposure and thrombin generation in plasma are fully dependent on Syk kinase activity. Tyrosine phosphorylation analysis confirms a key role of Syk activation, which is largely but not exclusively dependent on α(IIb)β(3) activation. It is concluded that the majority of tissue factor-induced procoagulant activity of platelets relies on Syk activation and ensuing Ca(2+) signal generation, and furthermore that a considerable part of Syk activation relies on α(IIb)β(3) signaling. These results hence point to a novel role of Syk in integrin-dependent thrombin generation.

  6. Maintaining vigilance on a simulated ATC monitoring task across repeated sessions.

    DOT National Transportation Integrated Search

    1994-03-01

    Maintaining alertness to information provided visually is an important aspect of air traffic controllers' work. Improper or incomplete scanning and monitoring behavior is often referred to as one of the causal factors associated with operational erro...

  7. The Hedgehog Signal Transduction Network

    PubMed Central

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

    2013-01-01

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

  8. Ras signaling in aging and metabolic regulation.

    PubMed

    Slack, Cathy

    2017-12-07

    Aberrant signal transduction downstream of the Ras GTPase has a well-established role in tumorigenesis. Mutations that result in hyperactivation of Ras are responsible for a third of all human cancers. Hence, small molecule inhibitors of the Ras signal transduction cascade have been under intense focus as potential cancer treatments. In both invertebrate and mammalian models, emerging evidence has also implicated components of the Ras signaling pathway in aging and metabolic regulation. Here, I review the current evidence for Ras signaling in these newly discovered roles highlighting the interactions between the Ras pathway and other longevity assurance mechanisms. Defining the role of Ras signaling in maintaining age-related health may have important implications for the development of interventions that could not only increase lifespan but also delay the onset and/or progression of age-related functional decline.

  9. Insulin-like growth factor-mediated muscle differentiation: collaboration between phosphatidylinositol 3-kinase-Akt-signaling pathways and myogenin.

    PubMed

    Tureckova, J; Wilson, E M; Cappalonga, J L; Rotwein, P

    2001-10-19

    The differentiation and maturation of skeletal muscle require interactions between signaling pathways activated by hormones and growth factors and an intrinsic regulatory network controlled by myogenic transcription factors. Insulin-like growth factors (IGFs) play key roles in muscle development in the embryo and in regeneration in the adult. To study mechanisms of IGF action in muscle, we developed a myogenic cell line that overexpresses IGF-binding protein-5. C2BP5 cells remain quiescent in low serum differentiation medium until the addition of IGF-I. Here we use this cell line to identify signaling pathways controlling IGF-mediated differentiation. Induction of myogenin by IGF-I and myotube formation were prevented by the phosphatidylinositol (PI) 3-kinase inhibitor, LY294002, even when included 2 days after growth factor addition, whereas expression of active PI 3-kinase could promote differentiation in the absence of IGF-I. Differentiation also was induced by myogenin but was blocked by LY294002. The differentiation-promoting effects of IGF-I were mimicked by a modified membrane-targeted inducible Akt-1 (iAkt), and iAkt was able to stimulate differentiation of C2 myoblasts and primary mouse myoblasts incubated with otherwise inhibitory concentrations of LY294002. These results show that an IGF-regulated PI 3-kinase-Akt pathway controls muscle differentiation by mechanisms acting both upstream and downstream of myogenin.

  10. Selective regulation of clathrin-mediated epidermal growth factor receptor signaling and endocytosis by phospholipase C and calcium

    PubMed Central

    Delos Santos, Ralph Christian; Bautista, Stephen; Lucarelli, Stefanie; Bone, Leslie N.; Dayam, Roya M.; Abousawan, John; Botelho, Roberto J.; Antonescu, Costin N.

    2017-01-01

    Clathrin-mediated endocytosis is a major regulator of cell-surface protein internalization. Clathrin and other proteins assemble into small invaginating structures at the plasma membrane termed clathrin-coated pits (CCPs) that mediate vesicle formation. In addition, epidermal growth factor receptor (EGFR) signaling is regulated by its accumulation within CCPs. Given the diversity of proteins regulated by clathrin-mediated endocytosis, how this process may distinctly regulate specific receptors is a key question. We examined the selective regulation of clathrin-dependent EGFR signaling and endocytosis. We find that perturbations of phospholipase Cγ1 (PLCγ1), Ca2+, or protein kinase C (PKC) impair clathrin-mediated endocytosis of EGFR, the formation of CCPs harboring EGFR, and EGFR signaling. Each of these manipulations was without effect on the clathrin-mediated endocytosis of transferrin receptor (TfR). EGFR and TfR were recruited to largely distinct clathrin structures. In addition to control of initiation and assembly of CCPs, EGF stimulation also elicited a Ca2+- and PKC-dependent reduction in synaptojanin1 recruitment to clathrin structures, indicating broad control of CCP assembly by Ca2+ signals. Hence EGFR elicits PLCγ1-calcium signals to facilitate formation of a subset of CCPs, thus modulating its own signaling and endocytosis. This provides evidence for the versatility of CCPs to control diverse cellular processes. PMID:28814502

  11. PPKs mediate direct signal transfer from phytochrome photoreceptors to transcription factor PIF3

    DOE PAGES

    Ni, Weimin; Xu, Shou-Ling; González-Grandío, Eduardo; ...

    2017-05-11

    Upon light-induced nuclear translocation, phytochrome (phy) sensory photoreceptors interact with, and induce rapid phosphorylation and consequent ubiquitin-mediated degradation of, transcription factors, called PIFs, thereby regulating target gene expression and plant development. Nevertheless, the biochemical mechanism of phy-induced PIF phosphorylation has remained ill-defined. Here in this paper we identify a family of nuclear protein kinases, designated Photoregulatory Protein Kinases (PPK1–4; formerly called MUT9-Like Kinases (MLKs)), that interact with PIF3 and phyB in a light-induced manner in vivo. Genetic analyses demonstrate that the PPKs are collectively necessary for the normal light-induced phosphorylation and degradation of PIF3. PPK1 directly phosphorylates PIF3 in vitro,more » with a phosphosite pattern that strongly mimics the light-induced pattern in vivo. These data establish that the PPKs are directly involved in catalysing the photoactivated-phy-induced phosphorylation of PIF3 in vivo, and thereby are critical components of a transcriptionally centred signalling hub that pleiotropically regulates plant growth and development in response to multiple signalling pathways.« less

  12. Polarization maintaining fiber magnetic sensor based on the digital phase generated carrier technology

    NASA Astrophysics Data System (ADS)

    Zhang, Xueliang; Meng, Zhou; Hu, Zhengliang; Yang, Huayong; Song, Zhangqi; Hu, Yongming

    2008-12-01

    A polarization maintaining fiber (PMF) magnetic field sensor based on a digital phase generated carrier (PGC) technology is presented. A magnetic sensor constructed with two magnetostrictive strips attached on the sensing fiber is joined in the sensing arm of a fiber Michelson interferometer. The fiber optic interferometric system is made of all PMF, which inhibits the polarization-induced signal fading. The light source is a fiber laser which can be modulated directly. The PGC metnod is used to demodulate magnetic field signal avoiding phase induced interferometric signal fading, and ensure the sensing partto be all fiber structure. A fiber optic magnetic field sensor with appreciate size for the fiber optic hydrophone towed array is obtained, which can be used to sense the enviromental magnetic field along the sensing direction.This sensor is a good choice for the directional angle measurement through sensing the Earth magnetic field in the array shape measurement of a fiber optic hydrophone towed array.

  13. Hypoxia inducible factor-1α regulates autophagy via the p27-E2F1 signaling pathway

    PubMed Central

    Wang, Pan; Long, Meijing; Zhang, Shijie; Cheng, Zhenyun; Zhao, Xin; He, Fucheng; Liu, Hongchun; Ming, Liang

    2017-01-01

    Autophagy is a highly conserved process by which the cell contents are delivered to lysosomes for degradation, or are used to provide macromolecules for energy generation under conditions of nutritional starvation. It has previously been demonstrated that cancer cells in hypoxic regions, with an oxygen concentration below the normal physiological level, express hypoxia inducible factor (HIF)-1α, in order to adapt and survive. HIF-1α is important in the regulation of oxygen homeostasis and the transcription of hundreds of genes in response to conditions of hypoxia, hence maintaining energy and redox homeostasis. To determine if HIF-1α modulates autophagy and the underlying molecular mechanisms regulating this process, the human esophageal cancer EC109 and IMR90 human diploid fibroblast cell lines were exposed to normoxic or hypoxic conditions and the expression levels of various proteins subsequently examined. Small interfering RNA was used to silence p27, in order to investigate its role in the process of HIF-1α regulated autophagy. Hypoxia induced autophagy in IMR90 cells and it was revealed that immature IMR90 cells demonstrated an increased rate of autophagy compared with mature cells. HIF-1α promoted EC109 cell autophagy via positively modulating p27, whereas silencing of p27 abolished the autophagy induced by hypoxia. The present study identified the primary components of the p27-E2F1 signaling pathway by which HIF-1α regulates autophagy. A previously unidentified mechanism is here presented, via which cancer cells may generate energy, or obtain macromolecules for survival. PMID:28627618

  14. Functional cloning of the proto-oncogene brain factor-1 (BF-1) as a Smad-binding antagonist of transforming growth factor-beta signaling.

    PubMed

    Rodriguez, C; Huang, L J; Son, J K; McKee, A; Xiao, Z; Lodish, H F

    2001-08-10

    Using the plasminogen activator inhibitor (PAI) promoter to drive the expression of a reporter gene (mouse CD2), we devised a system to clone negative regulators of the transforming growth factor-beta (TGF-beta) signaling pathway. We infected a TGF-beta-responsive cell line (MvLu1) with a retroviral cDNA library, selecting by fluorescence-activated cell sorter single cells displaying low PAI promoter activity in response to TGF-beta. Using this strategy we cloned the proto-oncogene brain factor-1 (BF-1). BF-1 represses the PAI promoter in part by associating with both unphosphorylated Smad3 (in the cytoplasm) and phosphorylated Smad3 (in the nucleus), thus preventing its binding to DNA. BF-1 also associates with Smad1, -2, and -4; the Smad MH2 domain binds to BF-1, and the C-terminal segment of BF-1 is uniquely and solely required for binding to Smads. Further, BF-1 represses another TGF-beta-induced promoter (p15), it up-regulates a TGF-beta-repressed promoter (Cyclin A), and it reverses the growth arrest caused by TGF-beta. Our results suggest that BF-1 is a general inhibitor of TGF-beta signaling and as such may play a key role during brain development.

  15. Sympathetically maintained pain presenting first as temporomandibular disorder, then as parotid dysfunction.

    PubMed

    Giri, Subha; Nixdorf, Donald

    2007-08-01

    Complex regional pain syndrome (CRPS) is a chronic condition that usually affects extremities, such as the arms or legs. It is characterized by intense pain, swelling, redness, hypersensitivity in a region not defined by a single peripheral nerve and additional sudomotor effects, such as excessive sweating. The clinical criteria for the diagnosis of sympathetically maintained pain as outlined by the International Association for the Study of Pain include: Onset following an initiating noxious event (CRPS-type I) or nerve injury (CRPS-type II). Spontaneous allodynia that is not limited to peripheral nerve distribution and is not proportionate to the inciting event; abnormal sudomotor activity, skin blood flow abnormality, edema, other autonomic symptoms; and exclusion of other conditions that may otherwise contribute to the extent of the symptoms. Only 13 cases of CRPS involving sympathetically maintained pain in the head and neck region have been described, and all reported trauma as the identifiable etiologic factor. The case presented here is another occurrence of sympathetically maintained pain in the head and neck region, but without nerve injury as a clear initiating factor.

  16. In vitro V(D)J recombination: signal joint formation.

    PubMed

    Cortes, P; Weis-Garcia, F; Misulovin, Z; Nussenzweig, A; Lai, J S; Li, G; Nussenzweig, M C; Baltimore, D

    1996-11-26

    The first step of V(D)J recombination, specific cleavage at the recombination signal sequence (RSS), can be carried out by the recombination activating proteins RAG1 and RAG2. In vivo, the cleaved coding and signal ends must be rejoined to generate functional antigen receptors and maintain chromosomal integrity. We have investigated signal joint formation using deletion and inversion substrates in a cell free system. RAG1 and RAG2 alone or in combination were unable to generate signal joints. However, RAG1 and RAG2 complemented with nuclear extracts were able to recombine an extrachromosomal substrate and form precise signal joints. The in vitro reaction resembled authentic V(D)J recombination in being Ku-antigen-dependent.

  17. Engineering Probiotics that Improve Warfighter Performance by Maintaining Lean Body Mass and Inhibiting Anxiety

    DTIC Science & Technology

    2017-10-03

    and Microbiome Research Seminar Series . Baylor College of Medicine. 10/26/16. 12. "Rewiring the DNA binding domains ofbacterial two-component system...Structural and Quantitative Biology Seminar Series . 11/16/15. 16. "Engineering bacterial two component signal transduction systems to function as sensors...hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and

  18. Selective role for RGS12 as a Ras/Raf/MEK scaffold in nerve growth factor-mediated differentiation

    PubMed Central

    Willard, Melinda D; Willard, Francis S; Li, Xiaoyan; Cappell, Steven D; Snider, William D; Siderovski, David P

    2007-01-01

    Regulator of G-protein signaling (RGS) proteins accelerate GTP hydrolysis by heterotrimeric G-protein α subunits and thus inhibit signaling by many G protein-coupled receptors. Several RGS proteins have a multidomain architecture that adds further complexity to their roles in cell signaling in addition to their GTPase-accelerating activity. RGS12 contains a tandem repeat of Ras-binding domains but, to date, the role of this protein in Ras-mediated signal transduction has not been reported. Here, we show that RGS12 associates with the nerve growth factor (NGF) receptor tyrosine kinase TrkA, activated H-Ras, B-Raf, and MEK2 and facilitates their coordinated signaling to prolonged ERK activation. RGS12 is required for NGF-mediated neurite outgrowth of PC12 cells, but not outgrowth stimulated by basic fibroblast growth factor. siRNA-mediated knockdown of RGS12 expression also inhibits NGF-induced axonal growth in dissociated cultures of primary dorsal root ganglia neurons. These data suggest that RGS12 may play a critical, and receptor-selective, role in coordinating Ras-dependent signals that are required for promoting and/or maintaining neuronal differentiation. PMID:17380122

  19. Transcriptome Profiling Reveals the Negative Regulation of Multiple Plant Hormone Signaling Pathways Elicited by Overexpression of C-Repeat Binding Factors.

    PubMed

    Li, Aixin; Zhou, Mingqi; Wei, Donghui; Chen, Hu; You, Chenjiang; Lin, Juan

    2017-01-01

    C-repeat binding factors (CBF) are a subfamily of AP2 transcription factors that play critical roles in the regulation of plant cold tolerance and growth in low temperature. In the present work, we sought to perform a detailed investigation into global transcriptional regulation of plant hormone signaling associated genes in transgenic plants engineered with CBF genes. RNA samples from Arabidopsis thaliana plants overexpressing two CBF genes, CBF2 and CBF3 , were subjected to Illumina HiSeq 2000 RNA sequencing (RNA-Seq). Our results showed that more than half of the hormone associated genes that were differentially expressed in CBF2 or CBF3 transgenic plants were related to auxin signal transduction and metabolism. Most of these alterations in gene expression could lead to repression of auxin signaling. Accordingly, the IAA content was significantly decreased in young tissues of plants overexpressing CBF2 and CBF3 compared with wild type. In addition, genes associated with the biosynthesis of Jasmonate (JA) and Salicylic acid (SA), as well as the signal sensing of Brassinolide (BR) and SA, were down-regulated, while genes associated with Gibberellin (GA) deactivation were up-regulated. In general, overexpression of CBF2 and CBF3 negatively affects multiple plant hormone signaling pathways in Arabidopsis . The transcriptome analysis using CBF2 and CBF3 transgenic plants provides novel and integrated insights into the interaction between CBFs and plant hormones, particularly the modulation of auxin signaling, which may contribute to the improvement of crop yields under abiotic stress via molecular engineering using CBF genes.

  20. Transcriptome Profiling Reveals the Negative Regulation of Multiple Plant Hormone Signaling Pathways Elicited by Overexpression of C-Repeat Binding Factors

    PubMed Central

    Li, Aixin; Zhou, Mingqi; Wei, Donghui; Chen, Hu; You, Chenjiang; Lin, Juan

    2017-01-01

    C-repeat binding factors (CBF) are a subfamily of AP2 transcription factors that play critical roles in the regulation of plant cold tolerance and growth in low temperature. In the present work, we sought to perform a detailed investigation into global transcriptional regulation of plant hormone signaling associated genes in transgenic plants engineered with CBF genes. RNA samples from Arabidopsis thaliana plants overexpressing two CBF genes, CBF2 and CBF3, were subjected to Illumina HiSeq 2000 RNA sequencing (RNA-Seq). Our results showed that more than half of the hormone associated genes that were differentially expressed in CBF2 or CBF3 transgenic plants were related to auxin signal transduction and metabolism. Most of these alterations in gene expression could lead to repression of auxin signaling. Accordingly, the IAA content was significantly decreased in young tissues of plants overexpressing CBF2 and CBF3 compared with wild type. In addition, genes associated with the biosynthesis of Jasmonate (JA) and Salicylic acid (SA), as well as the signal sensing of Brassinolide (BR) and SA, were down-regulated, while genes associated with Gibberellin (GA) deactivation were up-regulated. In general, overexpression of CBF2 and CBF3 negatively affects multiple plant hormone signaling pathways in Arabidopsis. The transcriptome analysis using CBF2 and CBF3 transgenic plants provides novel and integrated insights into the interaction between CBFs and plant hormones, particularly the modulation of auxin signaling, which may contribute to the improvement of crop yields under abiotic stress via molecular engineering using CBF genes. PMID:28983312

  1. Localization and signaling patterns of vascular endothelial growth factors and receptors in human periapical lesions.

    PubMed

    Virtej, Anca; Løes, Sigbjørn S; Berggreen, Ellen; Bletsa, Athanasia

    2013-05-01

    Vascular endothelial growth factors (VEGFs) and their receptors (VEGFRs) are key players in vasculogenesis and are also involved in pathologic conditions with bone destruction. Vasculogenesis is critical for disease progression, and bone resorption is a hallmark of apical periodontitis. However, the localization of VEGFs and VEGFRs and their gene signaling pathways in human apical periodontitis have not been thoroughly investigated. The aim of this study was to localize VEGFs and VEGFRs and analyze their gene expression as well as signaling pathways in human periapical lesions. Tissue was collected after endodontic surgery from patients diagnosed with chronic apical periodontitis. Periodontal ligament samples from extracted healthy wisdom teeth was also collected and used as control tissue. In lesion cryosections, VEGFs/VEGFRs were identified by immunohistochemistry/double immunofluorescence by using specific antibodies. A human VEGF signaling polymerase chain reaction array system was used for gene expression analysis comparing lesions with periodontal ligament samples. The histologic evaluation revealed heterogeneous morphology of the periapical lesions with various degrees of inflammatory infiltrates. In the lesions, all investigated factors and receptors were identified in blood vessels and various immune cells. No lymphatic vessels were detected. Gene expression analysis revealed up-regulation of VEGF-A and VEGFR-3, although not significant. Phosphatidylinositol-3-kinases, protein kinase C, mitogen-activated protein kinases, and phospholipases, all known to be involved in VEGF-mediated angiogenic activity, were significantly up-regulated. The cellular and vascular expressions of VEGFs and VEGFRs in chronic apical periodontitis, along with significant alterations of genes mediating VEGF-induced angiogenic responses, suggest ongoing vascular remodeling in established chronic periapical lesions. Copyright © 2013 American Association of Endodontists. Published by

  2. [The role of transforming growth factor-β1/connective tissue growth factor signaling pathway in paraquat-induced pulmonary fibrosis].

    PubMed

    Li, H H; Cai, Q; Wang, Y P; Liu, H R; Huang, M

    2016-07-20

    Objective: To investigate the effects of Paraquat on human embryonic lung fibroblasts (MRC5) and explore the role of transforming growth factor-β 1 /connective tissue growth factor signaling pathway in paraquat-induced pulmonary fibrosis. Methods: MRC5 cells were cultured with different concentration of PQ (0, 12.5, 25, 50, 100, 200, 400 μmol/L) for 24 h. The viability of cells was measured by MTT. The protein level of TGF-β 1 were analyzed by ELISA after PQ treatment (0, 25, 50, 100 μmol/L) . To examine whether TGF-β 1 /CTGF signaling pathway was involved in paraquat-induced cytotoxicity, cells was divided into 6 groups: (1) control; (2) 25 μmol/L PQ group; (3) 50 μmol/L PQ group; (4) 100 μmol/L PQ group; (5) TGF-β 1 positive control group (50 μmol/L rhTGF-β 1 ) ; (6) stimulate group (100 μmol/L PQ+50 μmol/L TGF-β 1 ) . The protein levels of p-Smad2, p-Smad3 and CTGF were assayed by western blot. The mRNA level of CTGF was assayed by real time RT-PCR. Results: MTT showed that cell viability decreased with increasing PQ concentration ( P <0.05) . The protein expression of TGF-β 1 treated with PQ (25, 50, 100 μmol/L) significantly increased compared with control in a dose-independent manner ( P <0.05) . Exposure to PQ (25, 50, 100 μmol/L) induced increase of protein levels of p-Smad2 and p-Smad3. Noteworthy, the expression of p-Smad2 and p-Smad3 were dramatically increased following PQ plus TGF-β 1 stimulation ( P <0.05) . Exposure to PQ (50, 100μmol/L) induced increase of CTGF protein expression and similar greatly increase following PQ plus TGF-β 1 stimulation ( P <0.05) . Real time RT-PCR showed CTGF mRNA in all groups also significantly up-regulated compared with control ( P <0.05) . Conclusion: TGF-β 1 regulates the expression of target gene CTGF to exhibit its pro-fibrogenic effects by activating TGF-β 1 /Smad signaling pathway in PQ-induced pulmonary fibrosis.

  3. Matriptase activation connects tissue factor-dependent coagulation initiation to epithelial proteolysis and signaling.

    PubMed

    Le Gall, Sylvain M; Szabo, Roman; Lee, Melody; Kirchhofer, Daniel; Craik, Charles S; Bugge, Thomas H; Camerer, Eric

    2016-06-23

    The coagulation cascade is designed to sense tissue injury by physical separation of the membrane-anchored cofactor tissue factor (TF) from inactive precursors of coagulation proteases circulating in plasma. Once TF on epithelial and other extravascular cells is exposed to plasma, sequential activation of coagulation proteases coordinates hemostasis and contributes to host defense and tissue repair. Membrane-anchored serine proteases (MASPs) play critical roles in the development and homeostasis of epithelial barrier tissues; how MASPs are activated in mature epithelia is unknown. We here report that proteases of the extrinsic pathway of blood coagulation transactivate the MASP matriptase, thus connecting coagulation initiation to epithelial proteolysis and signaling. Exposure of TF-expressing cells to factors (F) VIIa and Xa triggered the conversion of latent pro-matriptase to an active protease, which in turn cleaved the pericellular substrates protease-activated receptor-2 (PAR2) and pro-urokinase. An activation pathway-selective PAR2 mutant resistant to direct cleavage by TF:FVIIa and FXa was activated by these proteases when cells co-expressed pro-matriptase, and matriptase transactivation was necessary for efficient cleavage and activation of wild-type PAR2 by physiological concentrations of TF:FVIIa and FXa. The coagulation initiation complex induced rapid and prolonged enhancement of the barrier function of epithelial monolayers that was dependent on matriptase transactivation and PAR2 signaling. These observations suggest that the coagulation cascade engages matriptase to help coordinate epithelial defense and repair programs after injury or infection, and that matriptase may contribute to TF-driven pathogenesis in cancer and inflammation.

  4. ATRIAL NATRIURETIC FACTOR RECEPTOR GUANYLATE CYCLASE SIGNALING: NEW ATP- REGULATED TRANSDUCTION MOTIF

    PubMed Central

    Duda, Teresa; Bharill, Shashank; Wojtas, Ireneusz; Yadav, Prem; Gryczynski, Ignacy; Gryczynski, Zygmunt; Sharma, Rameshwar K.

    2010-01-01

    ANF-RGC$ membrane guanylate cyclase is the receptor for the hypotensive peptide hormones, atrial natriuretic factor (ANF) and type B natriuretic peptide (BNP). It is a single transmembrane spanning protein. Binding the hormone to the extracellular domain activates its intracellular catalytic domain. This results in accelerated production of cyclic GMP, a second messenger in controlling blood pressure, cardiac vasculature and fluid secretion. ATP is the obligatory transducer of the ANF signal. It works through its ATP regulated module, ARM, which is juxtaposed to the C-terminal side of the transmembrane domain. Upon interaction, ATP induces a cascade of temporal and spatial changes in the ARM, which, finally, result in activation of the catalytic module. Although the exact nature and the details of these changes are not known, some of these have been stereographed in the simulated three-dimensional model of the ARM and validated biochemically. Through comprehensive techniques ofsteady-state, time-resolved tryptophan fluorescence and Forster Resonance Energy Transfer (FRET), site-directed and deletion-mutagenesis, and reconstitution, the present study validates and explains themechanism of the model-based predicted transduction role of the ARM’s structural motif, 669WTAPELL675. This motif is critical in the ATP-dependent ANF signaling. Molecular modeling shows that ATP binding exposes the 669WTAPELL675 motif, the exposure, in turn, facilitates its interaction and activation of the catalytic module. These principles of the model have been experimentally validated. This knowledge brings us a step closer to our understanding of the mechanism by which the ATP-dependent spatial changes within the ARM cause ANF signaling of ANF-RGC. PMID:19137266

  5. Sprouty2 controls proliferation of palate mesenchymal cells via fibroblast growth factor signaling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Matsumura, Kaori; Taketomi, Takaharu, E-mail: taketomi@dent.kyushu-u.ac.jp; Yoshizaki, Keigo

    2011-01-28

    Research highlights: {yields} Sprouty2-deficient mice exhibit cleft palate as a result of failure of palatal shelf elevation. {yields} We examined palate cell proliferation in Sprouty2-deficient mice. {yields} Palate mesenchymal cell proliferation was increased in Sprouty2 KO mice. {yields} Sprouty2 plays roles in murine palatogenesis by regulating cell proliferation. -- Abstract: Cleft palate is one of the most common craniofacial deformities. The fibroblast growth factor (FGF) plays a central role in reciprocal interactions between adjacent tissues during palatal development, and the FGF signaling pathway has been shown to be inhibited by members of the Sprouty protein family. In this study, wemore » report the incidence of cleft palate, possibly caused by failure of palatal shelf elevation, in Sprouty2-deficient (KO) mice. Sprouty2-deficient palates fused completely in palatal organ culture. However, palate mesenchymal cell proliferation estimated by Ki-67 staining was increased in Sprouty2 KO mice compared with WT mice. Sprouty2-null palates expressed higher levels of FGF target genes, such as Msx1, Etv5, and Ptx1 than WT controls. Furthermore, proliferation and the extracellular signal-regulated kinase (Erk) activation in response to FGF was enhanced in palate mesenchymal cells transfected with Sprouty2 small interfering RNA. These results suggest that Sprouty2 regulates palate mesenchymal cell proliferation via FGF signaling and is involved in palatal shelf elevation.« less

  6. Key Transcription Factors in the Differentiation of Mesenchymal Stem Cells

    PubMed Central

    Almalki, Sami G.; Agrawal, Devendra K.

    2016-01-01

    Mesenchymal stem cells (MSCs) are multipotent cells that represent a promising source for regenerative medicine. MSCs are capable of osteogenic, chondrogenic, adipogenic and myogenic differentiation. Efficacy of differentiated MSCs to regenerate cells in the injured tissues requires the ability to maintain the differentiation toward the desired cell fate. Since MSCs represent an attractive source for autologous transplantation, cellular and molecular signaling pathways and micro-environmental changes have been studied in order to understand the role of cytokines, chemokines, and transcription factors on the differentiation of MSCs. The differentiation of MSC into a mesenchymal lineage is genetically manipulated and promoted by specific transcription factors associated with a particular cell lineage. Recent studies have explored the integration of transcription factors, including Runx2, Sox9, PPARγ, MyoD, GATA4, and GATA6 in the differentiation of MSCs. Therefore, the overexpression of a single transcription factor in MSCs may promote trans-differentiation into specific cell lineage, which can be used for treatment of some diseases. In this review, we critically discussed and evaluated the role of transcription factors and related signaling pathways that affect the differentiation of MSCs toward adipocytes, chondrocytes, osteocytes, skeletal muscle cells, cardiomyocytes, and smooth muscle cells. PMID:27012163

  7. BMP signaling balances proliferation and differentiation of muscle satellite cell descendants

    PubMed Central

    2011-01-01

    Background The capacity of muscle to grow or to regenerate after damage is provided by adult stem cells, so called satellite cells, which are located under the basement lamina of each myofiber. Upon activation satellite cells enter the cell cycle, proliferate and differentiate into myoblasts, which fuse to injured myofibers or form new fibers. These processes are tightly controlled by many growth factors. Results Here we investigate the role of bone morphogenetic proteins (BMPs) during satellite cell differentiation. Unlike the myogenic C2C12 cell line, primary satellite cells do not differentiate into osteoblasts upon BMP signaling. Instead BMP signaling inhibits myogenic differentiation of primary satellite cells ex vivo. In contrast, inhibition of BMP signaling results in cell cycle exit, followed by enhanced myoblast differentiation and myotube formation. Using an in vivo trauma model we demonstrate that satellite cells respond to BMP signals during the regeneration process. Interestingly, we found the BMP inhibitor Chordin upregulated in primary satellite cell cultures and in regenerating muscles. In both systems Chordin expression follows that of Myogenin, a marker for cells committed to differentiation. Conclusion Our data indicate that BMP signaling plays a critical role in balancing proliferation and differentiation of activated satellite cells and their descendants. Initially, BMP signals maintain satellite cells descendants in a proliferating state thereby expanding cell numbers. After cells are committed to differentiate they upregulate the expression of the BMP inhibitor Chordin thereby supporting terminal differentiation and myotube formation in a negative feedback mechanism. PMID:21645366

  8. Ecm33 is a novel factor involved in efficient glucose uptake for nutrition-responsive TORC1 signaling in yeast.

    PubMed

    Umekawa, Midori; Ujihara, Masato; Nakai, Daiki; Takematsu, Hiromu; Wakayama, Mamoru

    2017-11-01

    Glucose uptake is crucial for providing both an energy source and a signal that regulates cell proliferation. Therefore, it is important to clarify the mechanisms underlying glucose uptake and its transmission to intracellular signaling pathways. In this study, we searched for a novel regulatory factor involved in glucose-induced signaling by using Saccharomyces cerevisiae as a eukaryotic model. Requirement of the extracellular protein Ecm33 in efficient glucose uptake and full activation of the nutrient-responsive TOR kinase complex 1 (TORC1) signaling pathway is shown. Cells lacking Ecm33 elicit a series of starvation-induced pathways even in the presence of extracellular high glucose concentration. This results in delayed cell proliferation, reduced ATP, induction of autophagy, and dephosphorylation of the TORC1 substrates Atg13 and Sch9. © 2017 Federation of European Biochemical Societies.

  9. Alternative Oxidase: A Mitochondrial Respiratory Pathway to Maintain Metabolic and Signaling Homeostasis during Abiotic and Biotic Stress in Plants

    PubMed Central

    Vanlerberghe, Greg C.

    2013-01-01

    Alternative oxidase (AOX) is a non-energy conserving terminal oxidase in the plant mitochondrial electron transport chain. While respiratory carbon oxidation pathways, electron transport, and ATP turnover are tightly coupled processes, AOX provides a means to relax this coupling, thus providing a degree of metabolic homeostasis to carbon and energy metabolism. Beside their role in primary metabolism, plant mitochondria also act as “signaling organelles”, able to influence processes such as nuclear gene expression. AOX activity can control the level of potential mitochondrial signaling molecules such as superoxide, nitric oxide and important redox couples. In this way, AOX also provides a degree of signaling homeostasis to the organelle. Evidence suggests that AOX function in metabolic and signaling homeostasis is particularly important during stress. These include abiotic stresses such as low temperature, drought, and nutrient deficiency, as well as biotic stresses such as bacterial infection. This review provides an introduction to the genetic and biochemical control of AOX respiration, as well as providing generalized examples of how AOX activity can provide metabolic and signaling homeostasis. This review also examines abiotic and biotic stresses in which AOX respiration has been critically evaluated, and considers the overall role of AOX in growth and stress tolerance. PMID:23531539

  10. Aortopathy in a Mouse Model of Marfan Syndrome Is Not Mediated by Altered Transforming Growth Factor β Signaling.

    PubMed

    Wei, Hao; Hu, Jie Hong; Angelov, Stoyan N; Fox, Kate; Yan, James; Enstrom, Rachel; Smith, Alexandra; Dichek, David A

    2017-01-24

    Marfan syndrome (MFS) is caused by mutations in the gene encoding fibrillin-1 (FBN1); however, the mechanisms through which fibrillin-1 deficiency causes MFS-associated aortopathy are uncertain. Recently, attention was focused on the hypothesis that MFS-associated aortopathy is caused by increased transforming growth factor-β (TGF-β) signaling in aortic medial smooth muscle cells (SMC). However, there are many reasons to doubt that TGF-β signaling drives MFS-associated aortopathy. We used a mouse model to test whether SMC TGF-β signaling is perturbed by a fibrillin-1 variant that causes MFS and whether blockade of SMC TGF-β signaling prevents MFS-associated aortopathy. MFS mice (Fbn1 C1039G/+ genotype) were genetically modified to allow postnatal SMC-specific deletion of the type II TGF-β receptor (TBRII; essential for physiologic TGF-β signaling). In young MFS mice with and without superimposed deletion of SMC-TBRII, we measured aortic dimensions, histopathology, activation of aortic SMC TGF-β signaling pathways, and changes in aortic SMC gene expression. Young Fbn1 C1039G/+ mice had ascending aortic dilation and significant disruption of aortic medial architecture. Both aortic dilation and disrupted medial architecture were exacerbated by superimposed deletion of TBRII. TGF-β signaling was unaltered in aortic SMC of young MFS mice; however, SMC-specific deletion of TBRII in Fbn1 C1039G/+ mice significantly decreased activation of SMC TGF-β signaling pathways. In young Fbn1 C1039G/+ mice, aortopathy develops in the absence of detectable alterations in SMC TGF-β signaling. Loss of physiologic SMC TGF-β signaling exacerbates MFS-associated aortopathy. Our data support a protective role for SMC TGF-β signaling during early development of MFS-associated aortopathy. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  11. Overcoming low-alignment signal contrast induced alignment failure by alignment signal enhancement

    NASA Astrophysics Data System (ADS)

    Lee, Byeong Soo; Kim, Young Ha; Hwang, Hyunwoo; Lee, Jeongjin; Kong, Jeong Heung; Kang, Young Seog; Paarhuis, Bart; Kok, Haico; de Graaf, Roelof; Weichselbaum, Stefan; Droste, Richard; Mason, Christopher; Aarts, Igor; de Boeij, Wim P.

    2016-03-01

    Overlay is one of the key factors which enables optical lithography extension to 1X node DRAM manufacturing. It is natural that accurate wafer alignment is a prerequisite for good device overlay. However, alignment failures or misalignments are commonly observed in a fab. There are many factors which could induce alignment problems. Low alignment signal contrast is one of the main issues. Alignment signal contrast can be degraded by opaque stack materials or by alignment mark degradation due to processes like CMP. This issue can be compounded by mark sub-segmentation from design rules in combination with double or quadruple spacer process. Alignment signal contrast can be improved by applying new material or process optimization, which sometimes lead to the addition of another process-step with higher costs. If we can amplify the signal components containing the position information and reduce other unwanted signal and background contributions then we can improve alignment performance without process change. In this paper we use ASML's new alignment sensor (as was introduced and released on the NXT:1980Di) and sample wafers with special stacks which can induce poor alignment signal to demonstrate alignment and overlay improvement.

  12. The Drosophila Duox maturation factor is a key component of a positive feedback loop that sustains regeneration signaling.

    PubMed

    Khan, Sumbul Jawed; Abidi, Syeda Nayab Fatima; Skinner, Andrea; Tian, Yuan; Smith-Bolton, Rachel K

    2017-07-01

    Regenerating tissue must initiate the signaling that drives regenerative growth, and sustain that signaling long enough for regeneration to complete. How these key signals are sustained is unclear. To gain a comprehensive view of the changes in gene expression that occur during regeneration, we performed whole-genome mRNAseq of actively regenerating tissue from damaged Drosophila wing imaginal discs. We used genetic tools to ablate the wing primordium to induce regeneration, and carried out transcriptional profiling of the regeneration blastema by fluorescently labeling and sorting the blastema cells, thus identifying differentially expressed genes. Importantly, by using genetic mutants of several of these differentially expressed genes we have confirmed that they have roles in regeneration. Using this approach, we show that high expression of the gene moladietz (mol), which encodes the Duox-maturation factor NIP, is required during regeneration to produce reactive oxygen species (ROS), which in turn sustain JNK signaling during regeneration. We also show that JNK signaling upregulates mol expression, thereby activating a positive feedback signal that ensures the prolonged JNK activation required for regenerative growth. Thus, by whole-genome transcriptional profiling of regenerating tissue we have identified a positive feedback loop that regulates the extent of regenerative growth.

  13. The Drosophila Duox maturation factor is a key component of a positive feedback loop that sustains regeneration signaling

    PubMed Central

    Skinner, Andrea; Tian, Yuan

    2017-01-01

    Regenerating tissue must initiate the signaling that drives regenerative growth, and sustain that signaling long enough for regeneration to complete. How these key signals are sustained is unclear. To gain a comprehensive view of the changes in gene expression that occur during regeneration, we performed whole-genome mRNAseq of actively regenerating tissue from damaged Drosophila wing imaginal discs. We used genetic tools to ablate the wing primordium to induce regeneration, and carried out transcriptional profiling of the regeneration blastema by fluorescently labeling and sorting the blastema cells, thus identifying differentially expressed genes. Importantly, by using genetic mutants of several of these differentially expressed genes we have confirmed that they have roles in regeneration. Using this approach, we show that high expression of the gene moladietz (mol), which encodes the Duox-maturation factor NIP, is required during regeneration to produce reactive oxygen species (ROS), which in turn sustain JNK signaling during regeneration. We also show that JNK signaling upregulates mol expression, thereby activating a positive feedback signal that ensures the prolonged JNK activation required for regenerative growth. Thus, by whole-genome transcriptional profiling of regenerating tissue we have identified a positive feedback loop that regulates the extent of regenerative growth. PMID:28753614

  14. Rabex-5 ubiquitin ligase activity restricts Ras signaling to establish pathway homeostasis in Drosophila.

    PubMed

    Yan, Hua; Jahanshahi, Maryam; Horvath, Elizabeth A; Liu, Hsiu-Yu; Pfleger, Cathie M

    2010-08-10

    The Ras signaling pathway allows cells to translate external cues into diverse biological responses. Depending on context and the threshold reached, Ras signaling can promote growth, proliferation, differentiation, or cell survival. Failure to maintain precise control of Ras can have adverse physiological consequences. Indeed, excess Ras signaling disrupts developmental patterning and causes developmental disorders [1, 2], and in mature tissues, it can lead to cancer [3-5]. We identify Rabex-5 as a new component of Ras signaling crucial for achieving proper pathway outputs in multiple contexts in vivo. We show that Drosophila Rabex-5 restricts Ras signaling to establish organism size, wing vein pattern, and eye versus antennal fate. Rabex-5 has both Rab5 guanine nucleotide exchange factor (GEF) activity that regulates endocytic trafficking [6] and ubiquitin ligase activity [7, 8]. Surprisingly, overexpression studies demonstrate that Rabex-5 ubiquitin ligase activity, not its Rab5 GEF activity, is required to restrict wing vein specification and to suppress the eye phenotypes of oncogenic Ras expression. Furthermore, genetic interaction experiments indicate that Rabex-5 acts at the step of Ras, and tissue culture studies show that Rabex-5 promotes Ras ubiquitination. Together, these findings reveal a new mechanism for attenuating Ras signaling in vivo and suggest an important role for Rabex-5-mediated Ras ubiquitination in pathway homeostasis. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  15. Neuropeptide Trefoil Factor 3 Reverses Depressive-Like Behaviors by Activation of BDNF-ERK-CREB Signaling in Olfactory Bulbectomized Rats.

    PubMed

    Li, Jiali; Luo, Yixiao; Zhang, Ruoxi; Shi, Haishui; Zhu, Weili; Shi, Jie

    2015-11-30

    The trefoil factors (TFFs) are a family of three polypeptides, among which TFF1 and TFF3 are widely distributed in the central nervous system. Our previous study indicated that TFF3 was a potential rapid-onset antidepressant as it reversed the depressive-like behaviors induced by acute or chronic mild stress. In order to further identify the antidepressant-like effect of TFF3, we applied an olfactory bulbectomy (OB), a classic animal model of depression, in the present study. To elucidate the mechanism underlying the antidepressant-like activity of TFF3, we tested the role of brain-derived neurotrophic factor (BDNF)-extracellular signal-related kinase (ERK)-cyclic adenosine monophosphate response element binding protein (CREB) signaling in the hippocampus in the process. Chronic systemic administration of TFF3 (0.1 mg/kg, i.p.) for seven days not only produced a significant antidepressant-like efficacy in the OB paradigm, but also restored the expression of BDNF, pERK, and pCREB in the hippocampal CA3. Inhibition of BDNF or extracellular signal-related kinase (ERK) signaling in CA3 blocked the antidepressant-like activity of TFF3 in OB rats. Our findings further confirmed the therapeutic effect of TFF3 against depression and suggested that the normalization of the BDNF-ERK-CREB pathway was involved in the behavioral response of TFF3 for the treatment of depression.

  16. A regulatory role for TGF-β signaling in the establishment and function of the thymic medulla.

    PubMed

    Hauri-Hohl, Mathias; Zuklys, Saulius; Holländer, Georg A; Ziegler, Steven F

    2014-06-01

    Medullary thymic epithelial cells (mTECs) are critical in establishing and maintaining the appropriate microenvironment for negative selection and maturation of immunocompetent T cells with a self-tolerant T cell antigen receptor repertoire. Cues that direct proliferation and maturation of mTECs are provided by members of the tumor necrosis factor (TNF) superfamily expressed on developing thymocytes. Here we demonstrate a negative role of the morphogen TGF-β in tempering these signals under physiological conditions, limiting both growth and function of the thymic medulla. Eliminating TGF-β signaling specifically in TECs or by pharmacological means increased the size of the mTEC compartment, enhanced negative selection and functional maturation of medullary thymocytes as well as the production of regulatory T cells, thus reducing the autoreactive potential of peripheral T cells.

  17. Cardiotrophin-like cytokine factor 1 (CLCF1) and neuropoietin (NP) signalling and their roles in development, adulthood, cancer and degenerative disorders.

    PubMed

    Sims, Natalie A

    2015-10-01

    Mutations in cardiotrophin-like cytokine factor (CLCF1) and the related cytokine to which it binds, cytokine receptor-like factor 1 (CRLF1), are associated with Crisponi/cold induced sweating syndromes, and lead to early neonatal death in mice due to a suckling defect. These cytokines are members of the IL-6 superfamily, and form a range of composite cytokines that signal through gp130 bound either to the ciliary neurotrophic factor receptor (CNTFR) or a complex that involves the IL-27 p28 subunit. This review describes current knowledge of the signalling complexes formed by these cytokines, and explores their described and suggested roles in the neural, haematopoietic, skeletal, renal, immune and respiratory systems during development and adulthood, and in degenerative diseases and cancer. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Decoding Signal Processing at the Single-Cell Level

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wiley, H. Steven

    The ability of cells to detect and decode information about their extracellular environment is critical to generating an appropriate response. In multicellular organisms, cells must decode dozens of signals from their neighbors and extracellular matrix to maintain tissue homeostasis while still responding to environmental stressors. How cells detect and process information from their surroundings through a surprisingly limited number of signal transduction pathways is one of the most important question in biology. Despite many decades of research, many of the fundamental principles that underlie cell signal processing remain obscure. However, in this issue of Cell Systems, Gillies et al presentmore » compelling evidence that the early response gene circuit can act as a linear signal integrator, thus providing significant insight into how cells handle fluctuating signals and noise in their environment.« less

  19. Food-Sharing Networks in Lamalera, Indonesia: Status, Sharing, and Signaling

    PubMed Central

    Nolin, David A.

    2012-01-01

    Costly signaling has been proposed as a possible mechanism to explain food sharing in foraging populations. This sharing-as-signaling hypothesis predicts an association between sharing and status. Using exponential random graph modeling (ERGM), this prediction is tested on a social network of between-household food-sharing relationships in the fishing and sea-hunting village of Lamalera, Indonesia. Previous analyses (Nolin 2010) have shown that most sharing in Lamalera is consistent with reciprocal altruism. The question addressed here is whether any additional variation may be explained as sharing-as-signaling by high-status households. The results show that high-status households both give and receive more than other households, a pattern more consistent with reciprocal altruism than costly signaling. However, once the propensity to reciprocate and household productivity are controlled, households of men holding leadership positions show greater odds of unreciprocated giving when compared to households of non-leaders. This pattern of excessive giving by leaders is consistent with the sharing-as-signaling hypothesis. Wealthy households show the opposite pattern, giving less and receiving more than other households. These households may reciprocate in a currency other than food or their wealth may attract favor-seeking behavior from others. Overall, status covariates explain little variation in the sharing network as a whole, and much of the sharing observed by high-status households is best explained by the same factors that explain sharing by other households. This pattern suggests that multiple mechanisms may operate simultaneously to promote sharing in Lamalera and that signaling may motivate some sharing by some individuals even within sharing regimes primarily maintained by other mechanisms. PMID:22822299

  20. Glucocorticoid receptor signaling in health and disease

    PubMed Central

    Kadmiel, Mahita; Cidlowski, John A.

    2013-01-01

    Glucocorticoids are steroid hormones regulated in a circadian and stres-associated manner to maintain various metabolic and homeostatic functions that are necessary for life. Synthetic glucocorticoids are widely prescribed drugs for many conditions including asthma, chronic obstructive pulmonary disease (COPD), and inflammatory disorders of the eye. Research in the last few years has begun to unravel the profound complexity of glucocorticoid signaling and has contributed remarkably to improved therapeutic strategies. Glucocorticoids signal through the glucocorticoid receptor, a member of the superfamily of nuclear receptors, in both genomic and non-genomic ways in almost every tissue in the human body. In this review, we will provide an update on glucocorticoid receptor signaling and highlight the role of GR signaling in physiological and pathophysiological conditions in the major organ systems in the human body. PMID:23953592